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Lower extremity kinematics of athletics curve sprinting a
a
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Tobias Alt , Kai Heinrich , Johannes Funken & Wolfgang Potthast a
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany b
ARCUS Sports Clinic, Pforzheim, Germany Published online: 15 Dec 2014.
Click for updates To cite this article: Tobias Alt, Kai Heinrich, Johannes Funken & Wolfgang Potthast (2014): Lower extremity kinematics of athletics curve sprinting, Journal of Sports Sciences, DOI: 10.1080/02640414.2014.960881 To link to this article: http://dx.doi.org/10.1080/02640414.2014.960881
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Journal of Sports Sciences, 2014 http://dx.doi.org/10.1080/02640414.2014.960881
Lower extremity kinematics of athletics curve sprinting
TOBIAS ALT1, KAI HEINRICH1, JOHANNES FUNKEN1 & WOLFGANG POTTHAST1,2 1
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany and 2ARCUS Sports Clinic, Pforzheim, Germany
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(Accepted 29 August 2014)
Abstract Curve running requires the generation of centripetal force altering the movement pattern in comparison to the straight path run. The question arises which kinematic modulations emerge while bend sprinting at high velocities. It has been suggested that during curve sprints the legs fulfil different functions. A three-dimensional motion analysis (16 high-speed cameras) was conducted to compare the segmental kinematics of the lower extremity during the stance phases of linear and curve sprints (radius: 36.5 m) of six sprinters of national competitive level. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. During the prolonged left stance phase (left: 107.5 ms, right: 95.7 ms, straight: 104.4 ms) the maximum values of ankle eversion (left: 12.7°, right: 2.6°, straight: 6.6°), hip adduction (left: 13.8°, right: 5.5°, straight: 8.8°) and hip external rotation (left: 21.6°, right: 12.9°, straight: 16.7°) were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (eversion–adduction strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics. This helps to increase the understanding of nonlinear human bipedal locomotion, which in turn might lead to improvements in athletic performance and injury prevention. Keywords: sprint kinematics, joint angles, eversion, adduction, external rotation
1. Introduction In contrast to the linear run, the sprint along a bend track has attracted little attention in sports sciences although its portion is about 58% when competing in sprint distances above 100 m (Meinel, 2008). Especially when competing distances from 200 to 400 m this occurs with high velocities of more than 9 m · s–1 (Churchill, Salo, & Trewartha, 2011, 2012). Since it is suggested that in curve sprints the reorientation of the body is accompanied by three-dimensional changes in joint angles of the lower extremity especially with regard to the horizontal and transversal plane (Hamill, Murphy, & Sussman, 1987; Ishimura & Sakurai, 2010; Smith, Dyson, Hale, & Janaway, 2006), it can be deduced that two-dimensional motion analyses are not sufficient to generate a comprehensive understanding. A variety of studies suppose a symmetrical action of both legs during linear sprints (Kuitunen, Komi, & Kyrolainen, 2002; Mann & Hagy, 1980; Novacheck, 1998; Stafilidis & Arampatzis, 2007). However, Exell, Gittoes, Irwin, and Kerwin (2012) and Exell, Irwin, Gittoes, and Kerwin (2012) highlighted the individuality of asymmetry which was present in 39%
of kinematic and 23% of kinetic parameters analysed during maximal sprint running on a straight path. Other values failed to reach statistical significance due to large intra-limb individuality. During curve sprinting, asymmetric kinematic modulations (Chang & Kram, 2007; Hamill et al., 1987; Ishimura & Sakurai, 2010; Nemtsev & Chechin, 2010; Smith et al., 2006) seem to reduce the maximal sprinting velocity (Bezodis & Gittoes, 2008; Churchill et al., 2011, 2012; Greene, 1985; Luo & Stefanyshyn, 2012). Investigations reveal that this impairment might rise as the radius of curvature decreases (Jain, 1980). The negative effect of the bend track on further kinematic parameters such as a prolongation of both stance phases is presumed whereas the left ground contact time tends to be longer than the right one (Churchill et al., 2011, 2012; Ishimura & Sakurai, 2010; Usherwood & Wilson, 2005, 2006). As the moving direction of the athlete’s centre of mass cannot be influenced during the flight phase, the change of movement direction has to be realised during ground contact. It has been suggested that flight phases and step lengths might shorten during curve sprinting (Smith
Correspondence: Tobias Alt, Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933 Cologne, Germany. E-mail: [email protected] © 2014 Taylor & Francis
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et al., 2006) while the right step is assumed to be longer than the left step (Stoner & Ben-Sira, 1979). Biomechanical analyses of curve sprinting often deal with the question why its maximal velocity is lower than during linear sprints (Chang, Campbell, & Kram, 2001; Chang & Kram, 2007; Churchill et al., 2011, 2012). In contrast to a theoretical framework (Greene, 1985), which is based on the assumption that both legs act similarly during curved sprints, different functionalities of the inside and outside leg were assumed (Hamill et al., 1987; Ishimura & Sakurai, 2010; Nemtsev & Chechin, 2010; Smith et al., 2006). This should lead to restrictive propulsive mechanisms due to a stabilisation in the frontal and horizontal plane (Chang & Kram, 2007; Churchill et al., 2012), an uneven loading on biological tissues and thus to different muscular adaptations (Beukeboom, Birmingham, Forwell, & Ohrling, 2000). Since a limited three-dimensional description of track and field specific curve sprint kinematics is available (Churchill et al., 2011, 2012; Ishimura & Sakurai, 2010), this motor task and its related requirements are not well-understood. A better knowledge of the different movement pattern during curve sprinting could lead to potential performance improvement and better injury prevention. Therefore the question arises which kinematic modulations – compared to the straight path run – become apparent while bend sprinting at high velocities. Consequently, the purposes of this study are to identify differences of the three-dimensional joint kinematics between linear and curve sprinting and to describe the asymmetrical functionality of both legs during curve sprinting. Based on the current literature it was hypothesised that during sprints with equal velocity (1) stance times are prolonged during curve sprinting and (2) the inside and outside leg show different joint angles at hip, knee and ankle in all movement planes during curve sprinting and in comparison to linear sprints.
2. Methods 2.1. Experimental design To identify the effects of curved versus linear sprinting on general spatio-temporal parameters and kinematics of the lower extremity, this experimental cross-sectional single cohort study compared for linear and curved sprints stance time, flight time, step length and step frequency as well as lower extremity joint angles in all three movement planes. Sprinting movements were recorded using a three-dimensional motion analysis system. Joint angles were calculated using an inverse kinematic rigid-body-model. The radius of curvature was 36.5 m which represents the first lane of an IAAF 400 m standard track (Meinel, 2008).
2.2. Participant preparation Six male sprinters (age: 20.2 ± 2.6 years; height: 1.86 ± 0.06 m; mass: 76.3 ± 8.2 kg; 200 m personal best: 22.60 ± 0.33 s) of national competitive level gave their written consent to participate voluntarily in this study. At testing day they were healthy and without any physical complaint. During the testing procedure the participants wore their own sprint spikes. Anthropometric data were collected according to the multibody human model Dynamicus 7.0 (alaska® Dynamcius® 7.0, Institute of Mechatronics, Chemnitz, Germany). After an individual warm-up 32 spherical retro-reflective markers (Ø 13 mm, ILUMARK GmbH, Feldkirchen/Munich, Germany) were placed on anatomical landmarks (motion-marker) of the pelvis, thigh, shank, rearfoot and forefoot. The motion markers of the anatomical foot landmarks were placed on corresponding anatomical positions on the surface of the sprint spikes. Twenty-four additional markers on the upper extremity, trunk and head helped to determine the position and velocity of the centre of mass and had no influence on the calculation of the data of the lower extremity. 2.3. Technical setup and instrumentation Kinematic data were collected in a motion capture laboratory which was constructed on an indoor athletics track. They were determined using an infrared camera system (VICONTM, Oxford, UK) operating 16 infrared cameras (MX F40) at 250 Hz. The calibration volume (8 m long, 2 m wide and 2 m high) was placed tangentially in the summit of the curve. The bend track was marked with white adhesive tape. 2.4. Experimental protocol and data analysis All participants were asked to perform straight and curve sprints with a constant individual submaximal sprinting velocity which should be attained after an approach run of 40 m. In order to eliminate possible kinematic alterations due to different velocities (Arampatzis, Brüggemann, & Metzler, 1999; Hamill, Bates, Knutzen, & Sawhill, 1983), the athletes were asked to perform sprints at 90% of their perceived maximal linear sprint velocity. Sprinting velocities were monitored by two timing gates placed three metres apart in the middle of the calibration volume. Three valid trials for each sprinter per condition (linear, curve) each, where sprinting velocity was within a defined individual range (±0.2 m · s–1), were recorded. Kinematics were calculated with the aid of the human multi-body model Dynamicus® (Härtel & Hermsdorf, 2006). Each leg consists of four segments (thigh, lower leg, rearfoot and toe). The segments are connected with ball and socket
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Kinematics of curve sprinting joints with three degrees of freedom. Individual dimensions and inertial properties were determined by anthropometric measurements (body mass, body height, segment lengths, maximal and minimal segment circumferences). One trial was recorded while the participant was standing in an upright position to determine the neutral position of all joints. This static measurement served as reference for the following dynamic trials. All stride parameters were determined from kinematic data. The events touchdown and take-off were identified by the use of the “foot contact algorithm” recommended by Maiwald, Sterzing, Mayer, and Milani (2009). According to this algorithm step length was defined as the resultant distance in the horizontal plane (between the toes top markers) from touchdown of one foot till touchdown of the contra lateral foot, e.g. right step is from right till left touchdown. During flight phase the centre of mass moved in a linear fashion with respect to the ground. The time between touchdown and take-off of the same leg defined the stance time. Flight time was calculated as the time between takeoff of one leg to touchdown of the contra lateral leg. The reciprocal value of the time between touchdown of one leg and touchdown of the other leg described the step frequency. Velocity over a step was identified as mean horizontal velocity of the centre of mass after take-off of the respective foot. Descriptive and inferential statistics (mean ± S) were carried out over the performance variables as well as the minimal and maximal joint angles during stance phases under the four investigated conditions: left and right stance of linear and curve sprinting as mean values of individual athletes’ three trials. By means of a paired t-test (IBM SPSS Statistics 19, IBM Corporation, New York, USA) curve- (LL vs. CL, LR vs. CR) and side-specific effects (LL vs. LR, CL vs. CR) were analysed. Normal distribution (Kolmogorov–Smirnov test) was verified. An error probability (P) of under 5% represents a significant difference. Because of the small sample size statistical tendencies (P < 0.1) are also indicated. To underline the meaningfulness of the significant differences effect size (Cohen’s d) is reported. Besides the graphical presentation of averaged stance time normalised angle-time histories for all joints and movement planes during linear and curved sprinting (Figure 1) an angle–angle plot (Figure 2) emphasises the segmental interaction along a bend track in the frontal and transversal plane.
3. Results 3.1. Spatio-temporal parameters Table I lists the mean values and standard deviations of the step parameters. No statistical significance in
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sprinting velocity was found between linear and curve sprints (Table I). Flight time, step length and step frequency were not affected by the bend. The stance time of the inside leg during curve sprinting was significantly 11.8 ms (P = 0.000; d = 1.39) longer compared to the stance phase of the outside leg during curve sprinting. Both stance times during curve sprinting were different in relation to linear runs. The right side displayed a significant decrease of 8.2 ms (P = 0.001; d = 1.00), whereas the left side showed an increase by trend of 2.6 ms (P = 0.067; d = 0.29) (Table I). 3.2. Joint kinematics Figure 1 displays the averaged time normalised angle-time histories for all joints and movement planes during linear and curved sprinting. Table II shows the mean values and standard deviations of maximum and minimum angle excursions during the stance phase. The analysis of the left and right stance phase during linear sprints revealed no significant differences concerning the extreme values of the joint angles at the ankle, knee and hip (Table II). The left and right stance phase during curve sprinting showed significant differences in all three joints of the lower extremity. This similar segmental interaction occurred in the frontal as well as in the horizontal plane whereas the joint angles in the sagittal plane remained unchanged (Table II). The eversion angle of the left ankle joint was significantly 10.1° larger than the outside one (P = 0.021; d = 1.62). With regard to the hip joint the maximal adduction angle was larger during the left stance phase (P = 0.005; d = 2.13) (Table II). During the right stance phase peak external rotation of the ankle reached threefold values in comparison to the left one (P = 0.031; d = 1.31). The maximum internal rotation of the right knee was significantly higher compared to the left knee joint (P = 0.014; d = 0.76). Hip joint peak external rotation during left stance exceeded the values measured in the right hip by almost 9° (P = 0.033; d = 1.57). A difference by trend was found in the internal rotation suggesting higher angles in the right hip (Table II) (P = 0.074; d = 1.30). The comparison between linear and curve sprinting revealed significant kinematic modulations in the ankle and hip joint whereas the joint angles of the knee remained equal. In the left ankle the peak eversion angle in curve sprinting was twice as big (P = 0.037; d = 1.12) whereas the right stance phase showed lower values compared to the straight path run (P = 0.043; d = 0.83). During the left stance phase of curved sprints peak hip adduction was significantly greater (P = 0.004; d = 1.71). The
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Figure 1. Time histories (normalised stance phase) of the ankle, knee and hip angle in the sagittal (top row), frontal (middle row) and transversal plane (bottom row) under the four investigated conditions: curve inside (solid black line), curve outside (solid grey line), straight left (dashed black line) and straight right (dashed grey line).
Figure 2. Angle-to-angle relations (frontal and transversal plane) during curve sprinting (left: ankle joint, middle: knee joint, right: hip joint): curve inside (solid black line) and curve outside (solid grey line). The arrows indicate the direction during the stance phase.
right stance phases of linear runs showed larger ankle external rotation (P = 0.001; d = 0.87) and hip adduction angles (P = 0.026; d = 1.00) than the bend condition of the same leg (Table II). 4. Discussion The purpose of this study was to investigate the effect of curve sprinting on lower extremity kinematics for
the inside and outside leg in comparison to linear sprinting. Unlike in previous investigations (Churchill et al., 2011, 2012), the velocity was kept similar both in curve and straight sprinting in the current study. This eliminates the velocity-specific modulations (Arampatzis et al., 1999; Hamill et al., 1983). Instead the observed kinematic differences might be a result of the supplement force requirement in medio-lateral direction. Consequently, it was
Kinematics of curve sprinting Table I. Mean values, standard deviations (S) and 95% confidence intervals (CI) of kinematic data under the conditions linear left (LL), linear right (LR), curve left (CL) and curve right (CR).
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Velocity [m · s ] 95% CI [m · s–1] Step length [m] 95% CI [m] Stance time [ms] 95% CI [ms] Flight time [ms] 95% CI [ms] Step frequency [Hz] 95% CI [Hz]
LL
LR
CL
CR
9.24 ± 0.40 8.92−9.56 2.18 ± 0.11 2.09−2.27 104.9 ± 8.9(c) 97.8−112.0 131.2 ± 12.4 121.3−141.1 4.29 ± 0.25 4.09−4.49
9.25 ± 0.45 8.89−9.61 2.14 ± 0.12 2.04−2.24 103.9 ± 8.2d 97.3−110.5 127.0 ± 15.0 115.0−139.0 4.31 ± 0.24 4.12−4.50
9.26 ± 0.45 8.90−9.62 2.24 ± 0.10 2.16−2.32 107.5 ± 8.8(a) d 100.5−114.5 133.3 ± 8.7 126.3−140.3 4.13 ± 0.21 3.96−4.30
9.39 ± 0.25 9.19−9.59 2.24 ± 0.08 2.18−2.30 95.7 ± 8.2b c 89.2−102.3 135.7 ± 13.0 125.3−146.1 4.35 ± 0.23 4.17−4.53
Notes: a b c drepresent a significant difference (P < 0.05) with LL, LR, CL and CR, respectively. Tendencies (P < 0.1) are set in brackets.
Table II. Peak values, standard deviations [°] and 95% confidence intervals (CI) of the ankle, knee and hip joint under the conditions linear left (LL), linear right (LR), curve left (CL) and curve right (CR). LL
LR
CL
CR
Ankle Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Eversion [°] 95% CI [°] Inversion [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
26.2 ± 1.1 25.3−27.1 29.6 ± 6.3 24.6−34.6 6.7 ± 2.3c 4.9−8.5 9.3 ± 4.2 5.9−17.7 4.0 ± 2.0 2.4−5.6 6.9 ± 3.2 4.3−9.5
26.0 ± 1.7 24.6−27.4 30.0 ± 4.5 26.4−33.6 6.4 ± 4.0d 3.2−9.6 9.1 ± 2.4(d) 7.2−11.0 4.3 ± 3.7d 1.3−7.3 7.7 ± 4.0 4.5−10.9
26.8 ± 4.1 23.5−30.1 28.7 ± 5.4 24.4−33.0 12.7 ± 7.2a d 6.9−18.5 7.2 ± 6.4 2.1−12.3 2.4 ± 4.2d −1.0−5.8 6.6 ± 5.0 2.6−10.6
23.2 ± 6.0 18.4−28.0 29.5 ± 2.2 27.7−31.3 2.6 ± 5.1b c −1.5−6.7 10.4 ± 3.3(b) 7.8−13.0 7.3 ± 3.2b c 4.7−9.9 6.2 ± 2.9 3.9−8.5
Knee Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Abduction [°] 95% CI [°] Adduction [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
45.0 ± 4.2 41.6−48.4 18.2 ± 4.0 15.0−21.4 2.0 ± 3.7 −1.0−5.0 1.8 ± 3.0 −0.6−4.2 1.1 ± 2.9 −1.2−3.4 9.9 ± 4.1 6.6−13.2
44.8 ± 4.4 41.3−48.3 16.0 ± 2.0 14.4−17.6 2.8 ± 2.8 0.6−5.0 0.6 ± 3.1 −1.9−3.1 1.0 ± 3.8 −2.0−4.0 8.9 ± 4.2(d) 5.5−12.3
43.9 ± 6.4 38.8−49.0 17.1 ± 2.8 14.9−19.3 2.1 ± 3.3 −0.5−4.7 2.4 ± 3.7 −0.6−5.4 1.9 ± 5.1 −2.2−6.0 8.8 ± 5.3d 4.6−13.0
48.8 ± 7.1 43.1−54.5 18.6 ± 7.3 12.8−24.4 3.3 ± 2.3 1.5−5.1 −0.9 ± 2.8 −3.1−1.3 0.3 ± 4.0 −2.9−3.5 12.8 ± 5.2(b) 8.6−17.0
Hip Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Abduction [°] 95% CI [°] Adduction [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
25.2 ± 6.7 19.8−30.6 29.2 ± 3.5 26.4−32.0 7.1 ± 2.2 5.3−8.9 7.7 ± 3.8c 4.7−10.7 19.0 ± 4.1(b) 15.7−22.3 −1.5 ± 3.2 −4.1−1.1
25.6 ± 5.1 21.5−29.7 29.8 ± 3.3 27.2−32.4 8.1 ± 2.4 6.2−10.0 9.8 ± 4.2d 6.4−13.2 14.3 ± 4.1(a) 11.0−17.6 1.5 ± 4.0 −1.7−4.7
26.3 ± 5.4 22.0−30.6 31.5 ± 3.3 28.9−34.1 4.8 ± 3.0 2.4−7.2 13.8 ± 3.3a d 11.2−16.4 21.6 ± 6.7d 16.2−27.0 −4.6 ± 4.3(d) −8.0−−1.2
24.5 ± 4.4 21.0−28.0 27.6 ± 8.2 21.0−34.2 7.5 ± 4.4 4.0−11.0 5.5 ± 4.4b c 2.0−9.0 12.9 ± 4.1c 9.6−16.2 2.1 ± 5.9(c) −2.6−6.8
c
Notes: a b c drepresent a significant difference (P < 0.05) with LL, LR, CL and CR, respectively. Tendencies (P < 0.1) are set in brackets.
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assumed that the observed changes in segmental interaction of the lower extremity can be declared as curvespecific. If the selected sub-maximal velocity during linear sprints included a change in movement, behaviour is unknown. It has been hypothesised that during sprints with equal velocity (1) stance times are prolonged during curve sprinting and (2) the inside and outside leg show a different kinematic behaviour. Due to methodological differences in sprinting velocity and experimental setup the present results of the temporal–spatial parameters are contrary to previous studies (Smith et al., 2006; Stoner & Ben-Sira, 1979). Flight time, step length and step frequency did not differ during fixed-velocity curve sprints in comparison to linear ones. However, the left stance time during curve sprinting exceeded the right one significantly by 11.8 ms (P = 0.000; d = 1.39), a finding which is in accordance to Ishimura and Sakurai (2010) (CL: 125 ms; CR: 112 ms) and holds true during maximal curve sprints as well (Churchill et al., 2011). Therefore, hypothesis 1 is confirmed for the left leg and declined for the right. It has to be pointed out, that in curve running there are considerable differences between the velocity of the centre or mass and the product of step frequency and step length (Table I). The path the centre of mass travels during one step is not identical to the distance between point of touchdown of one leg and the point of the subsequent touchdown of the contralateral leg. This effect should be more pronounced in curve running in comparison to linear running, which still has to be confirmed by future studies. The analysis of the linear sprints indicated a similar segmental interaction of the lower extremity during the stance phase. Thus, the right and left stance phase during linear sprinting required similar demands to the musculo-skeletal system and motor control which confirms the current knowledge of lower extremity function during linear sprints (Kuitunen et al., 2002; Stafilidis & Arampatzis, 2007). Curve sprinting poses a high load to the sprinter’s foot muscles as a change in direction has to take place at high velocities within short stance times. During the stance phase of the inside foot a high ankle eversion occurred (CL: 12.7°; CR: 2.6°; P = 0.021; d = 1.62). According to Clarke, Frederick, and Hamill (1984) an eversion of almost 13° reaches unphysiological limits which might lead to injuries if it emerges repeatedly (Beukeboom et al., 2000). Nevertheless, the presented peak eversion angle did not reach by far the extent measured by Hamill et al. (1987) (CL: 22.3°; CR: 12.5°) and Smith et al. (2006)
(CL: 34.0°; CR: 6.7°). This discrepancy can be originated in different testing conditions (rearfoot runners, smaller radii). The present results indicated a different foot-planting pattern while bend sprinting (Figure 1). The right foot displayed an initial external rotation angle of 1.0° whereas the left foot was internally rotated (4.6°). During the stance phase, peak external rotation in the right ankle reached threefold values compared to the inside foot (CL: 2.4°; CR: 7.3; P = 0.031; d = 1.31) (Table II). Research about angular kinematics of the knee in the frontal and transversal plane is missing. Consequently, the significant higher internal rotation angle of the right knee (CL: 8.8°; CR: 12.8°; P = 0.014; d = 0.76) is a new finding leading to the idea that during the right stance phase transversal angular modulations are of special importance. As sagittal plane kinematics did not differ between linear and curved sprints the present results conflict with previous investigations. They claimed that knee flexion becomes greater during curve sprinting and that this amortisation increases with smaller radii of curvature (Churchill et al., 2011). This contradiction might be due to the fact that maximal sprinting velocities were investigated (Churchill et al., 2011). In the present case the peak hip adduction angle of the left leg reached more than twofold values (CL: 13.8°; CR: 5.5°; P = 0.005; d = 2.13) in comparison to the outside leg indicating a greater inward lean of the inside shank. This result is in accordance with previous findings (Churchill et al., 2011; Ishimura & Sakurai, 2010). However, in both studies the amount of the peak adduction was smaller (7.4° and 10.6°, respectively) probably because larger radii of curvature were investigated. Peak hip external rotation during left stance exceeded the values of the right hip (CL: 21.6°; CR: 12.9°; P = 0.033; d = 1.57). Since the transversal modulations induced by the bend have not been extensively analysed yet this kinematic feature is a new finding. During the prolonged left stance phase during curved sprints the supporting leg displayed high peak values of the ankle eversion, the hip adduction and the hip external rotation. Concerning the left knee joint no kinematic modulations became apparent. In contrast, right stance phase of curved sprints was characterised by high peak values of the ankle external rotation and the knee internal rotation. Additionally, a significantly lower maximum eversion angle of the ankle and hip adduction angle occurred. In summary, hypothesis 2 is accepted for frontal and transversal plane kinematics, but declined for the sagittal plane.
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Kinematics of curve sprinting In contrast to the comparable segmental interaction during the straight path run, curve sprinting posed different requirements on the inside and outside leg demonstrated in varying kinematic modulations (Figure 2). Several authors (Bezodis & Gittoes, 2008; Chang & Kram, 2007; Churchill et al., 2011, 2012; Hamill et al., 1987; Smith et al., 2006) suggested a different technique during curved sprints to generate the necessary centripetal force, but direct evidence was missing. The present kinematic analysis of step parameters and joint angles of the lower extremity during the stance phases supports the assumption that the inside and outside leg seem to fulfil different tasks during curve sprinting. An explanatory approach of the identified effects could be the fact that a greater adduction angle has to occur in the left hip if touchdown occurs with equal knee flexion, comparable height of the centre of mass and similar tilted hip axis (Churchill et al., 2011; Ishimura & Sakurai, 2010). Consequently, the inclination of the inside shank has to be greater (Hamill et al., 1987; Nemtsev & Chechin, 2010; Smith et al., 2006). During the left stance phase this inner inclination of the sprinter’s body leads to a significantly longer stance time and a greater eversion angle of the ankle. Recent research (Bezodis & Gittoes, 2008; Chang et al., 2001; Chang & Kram, 2007; Churchill et al., 2012; Luo & Stefanyshyn, 2012) pointed out that the inside leg has performance-limiting influence and thus is responsible for the significantly lower maximal sprint velocity during curved sprints. Based on the present study this question cannot be answered as the results rely on equal submaximal sprinting velocities. However, it can be supposed that the propulsion of the inside leg may be restricted since the centripetal force increases with the power of two with the sprinting velocity and the necessary stabilisation in the frontal and transversal plane becomes critical (Chang et al., 2001; Chang & Kram, 2007). Additionally the segmental orientation of the inside leg in curve sprinting is quite complex with an intensive external hip rotated combined with adduction, while the ankle is everted (Figure 2). This might be disadvantageous in terms of motor control and muscle lengths and therefore limits the propulsive capacity during left stance. Those limitations might rise if the radius of curvature decreases (Jain, 1980). This question may be answered by a kinetic analysis of the ankle, knee and hip joint moments occurring during the stance phase. During its stance phase the right leg underlies a longitudinal twisting as a prominent external rotation of the ankle and a high internal rotation angle of the knee occur simultaneously (Figure 1). In accordance with the lower external rotation angle of the hip this segmental interaction
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in the late right stance phase allows the push-off in the new direction. Overall, sprinting is only possible if the necessary centripetal force is generated. This additional task results in an inclination of the athlete’s body and several changes of the joint angles of the lower extremity, primarily in the frontal and transversal plane. The present three-dimensional motion analysis of both stance phases suggests that the sprinter applies an eversion–adduction strategy during the stance phase of the inside leg during curve sprinting. This becomes apparent as changes in the ankle and hip angles especially take place in the frontal plane compared to linear runs. Meanwhile, the outside leg accounts for several angular modifications in the transversal plane which may be summarised as rotational mechanism. This underlines the different functionality of inside and outside leg during curve sprinting (Figure 2). The present study aimed to establish discrete values of kinematic parameters during linear and curve sprints of equal sub-maximal velocity. It was found that the movement pattern during straight path run was comparable whereas the segmental action of curved locomotion was different. These results impose a more explicit research of asymmetrical kinematic behaviour during human bipedal locomotion which was beyond the scope of our investigation. The application of the symmetry angle method of Zifchock, Davis, Higginson, and Royer (2008) may demonstrate if the observed kinematic differences during curve sprinting are in fact proof of an asymmetrical technique. As Exell, Gittoes, Irwin, and Kerwin (2012) and Exell, Irwin, Gittoes, and Kerwin (2012) indicated that a high intra-limb individuality during sprint running causes misleading results if it is not included in asymmetry analyses, it is not appropriate to interpret the present results as symmetrical or asymmetrical kinematic behaviour. In general, further research is needed to extend the segmental interaction of both legs during their stance phase while running along a bend track. Additional information about the ground reaction forces and the joint moments based on a larger sample size will improve the understanding of the curve sprinting technique and its underlying propulsive and stabilising mechanisms. This will help to understand the functioning of both legs and to quantify the impact on biological tissues. Results of the ankle joint should be regarded with caution as the retro-reflective markers were attached on the shoes and not on the skin which might lead to small variations. Additional investigation is needed to prove if larger radii of curvature might have a
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positive effect on lower extremity function during curve sprinting.
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5. Conclusion This study offers an insight into the different technique during curve sprinting. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. Temporal–spatial parameters did not show any significant differences except stance time. During the prolonged left stance phase the maximum values of ankle eversion, hip adduction and hip external rotation were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (adduction–eversion strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics and may help to improve athletic performance. This comprehensive understanding of lower extremity kinematics during nonlinear human locomotion may in the long run be helpful both for coaches and athletes. It serves to understand the different technique of the legs during curve sprinting facilitating the movement perception as well as feedback of the coach and thus the technical improvement of the athlete. This can contribute to improve athletic performance by evaluating curve-specific technical and conditioning training programmes. Additionally, these findings may support physiotherapists in injury prevention by implementing explicit strengthening and mobility exercises of the foot muscles (Beukeboom et al., 2000).
Funding This study was supported by Nike Inc.
References Arampatzis, A., Brüggemann, G.-P., & Metzler, V. (1999). The effect of speed on leg stiffness and joint kinetics in human running. Journal of Biomechanics, 32(12), 1349– 1353. Beukeboom, C., Birmingham, T. B., Forwell, L., & Ohrling, D. (2000). Asymmetrical strength changes and injuries in athletes training on a small radius curve indoor track. Clinical Journal of Sport Medicine, 10(4), 245–250. Bezodis, I. N., & Gittoes, M. J. (2008). Bilateral differences in step characteristics when sprinting on straight and banked bend of an indoor 200 m track. In Y. H. Kwon, J. Shim, J. K. Shim, & I. S. Shin (Eds.), Proceedings of the 26th international conference on biomechanics in sports (pp. 673–676). Seoul: International Society of Biomechanics in Sports.
Chang, Y. H., Campbell, K., & Kram, R. (2001). Running speed on curved paths is limited by the inside leg. Proceedings of the 25th Conference of the American Society of Biomechanics, San Diego, CA. Chang, Y.-H., & Kram, R. (2007). Limitations to maximum running speed on flat curves. Journal of Experimental Biology, 210(6), 971–982. Churchill, S. M., Salo, A. I. T., & Trewartha, G. (2011). The effect of the bend on technique and performance during maximal speed sprinting. In J. P. Vilas-Boas, L. Machado, W. Kim, & A. P. Veloso (Eds.), Biomechanics in Sports 29, Portuguese Journal of Sports Sciences, 11(Suppl. 2), 471–474. Churchill, S. M., Salo, A. I. T., Trewartha, G., & Bezodis, I. N. (2012). Force production during maximal effort sprinting on the bend. In E. J. Bradshaw, A. Burnett, & P. A. Hume (Eds.), Proceedings of the 30th annual conference of biomechanics in sports (pp. 119–122). Melbourne: International Society of Biomechanics in Sports. Clarke, T. E., Frederick, E. C., & Hamill, J. (1984). The study of rearfoot movement in running. In E. C. Frederick (Ed.), Sport shoes and playing surfaces (pp. 166–189). Champaign, IL: Human Kinetics. Exell, T. A., Gittoes, M. J. R., Irwin, G., & Kerwin, D. G. (2012). Gait asymmetry: Composite scores for mechanical analyses of sprint running. Journal of Biomechanics, 45(6), 1108–1111. Exell, T. A., Irwin, G., Gittoes, M. J. R., & Kerwin, D. G. (2012). Implications of intra-limb variability on asymmetry analyses. Journal of Sports Sciences, 30(4), 403–409. Greene, P. R. (1985). Running on flat turns: Experiments, theory, and applications. Journal of Biomechanical EngineeringTransactions of the ASME, 107(2), 96–103. Hamill, J., Bates, B. T., Knutzen, K. M., & Sawhill, J. A. (1983). Variations in ground reaction force parameters at different running speeds. Human Movement Science, 2(1–2), 47–56. Hamill, J., Murphy, M., & Sussman, D. (1987). The effects of track turns on lower extremity function. International Journal of Sport Biomechanics, 3, 276–286. Härtel, T., & Hermsdorf, H. (2006). Biomechanical modelling and simulation of human body by means of DYNAMICUS. Journal of Biomechanics, 39(Suppl. 1), S549. Ishimura, K., & Sakurai, S. (2010). Comparison of inside contact phase and outside contact phase in curved sprinting. In R. Jensen, W. Ebben, E. Petushek, C. Richter, & K. Roemer (Eds.), Proceedings of the 28th international conference on biomechanics in sports. Marquette, MI: International Society of Biomechanics in Sports. Jain, P. C. (1980). On a discrepancy in track races. Research Quarterly for Exercise & Sport, 51(2), 432–436. Kuitunen, S., Komi, P. V., & Kyrolainen, H. (2002). Knee and ankle joint stiffness in sprint running. Medicine and Science in Sports and Exercise, 34(1), 166–173. Luo, G., & Stefanyshyn, D. J. (2012). Limb force and non-sagittal plane joint moments during maximum-effort curve sprint running in humans. The Journal of Experimental Biology, 215(24), 4314–4321. Maiwald, C., Sterzing, T., Mayer, T. A., & Milani, T. L. (2009). Detecting foot-to-ground contact from kinematic data in running. Footwear Science, 1(2), 111–118. Mann, R. A., & Hagy, J. (1980). Biomechanics of walking, running and sprinting. The American Journal of Sports Medicine, 8(5), 345–350. Meinel, K. (2008). Competition area. In International Association of Athletics Federations (Ed.), IAAF track and field facilities manual (pp. 31–54). Monaco: Multiprint. Nemtsev, O., & Chechin, A. (2010). Foot planting techniques when sprinting at curves. In R. Jensen, W. Ebben, E. Petushek, C. Richter, & K. Roemer (Eds.), Proceedings of the 28th international
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conference on biomechanics in sports. Marquette, MI: International Society of Biomechanics in Sports. Novacheck, T. F. (1998). The biomechanics of running. Gait & Posture, 7(1), 77–95. Smith, N., Dyson, R., Hale, T., & Janaway, L. (2006). Contributions of the inside and outside leg to maintenance of curvilinear motion on a natural turf surface. Gait & Posture, 24(4), 453–458. Stafilidis, S., & Arampatzis, A. (2007). Track compliance does not affect sprinting performance. Journal of Sports Sciences, 25, 1479–1490.
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Stoner, L. J., & Ben-Sira, D. (1979). Sprinting on the curve. In J. Terauds & G. G. Dale (Eds.), Science in athletics (pp. 167–173). Del Mar, CA: Academic. Usherwood, J. R., & Wilson, A. M. (2005). Biomechanics: No force limit on greyhound sprint speed. Nature, 438(7069), 753–754. Usherwood, J. R., & Wilson, A. M. (2006). Accounting for elite indoor 200 m sprint results. Biology Letters, 2(1), 47–50. Zifchock, R. A., Davis, I., Higginson, J., & Royer, T. (2008). The symmetry angle: A novel robust method of quantifying asymmetry. Gait and Posture, 27(4), 622–627.
Journal of Sports Sciences Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/rjsp20
Lower extremity kinematics of athletics curve sprinting a
a
a
ab
Tobias Alt , Kai Heinrich , Johannes Funken & Wolfgang Potthast a
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany b
ARCUS Sports Clinic, Pforzheim, Germany Published online: 15 Dec 2014.
Click for updates To cite this article: Tobias Alt, Kai Heinrich, Johannes Funken & Wolfgang Potthast (2014): Lower extremity kinematics of athletics curve sprinting, Journal of Sports Sciences, DOI: 10.1080/02640414.2014.960881 To link to this article: http://dx.doi.org/10.1080/02640414.2014.960881
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Journal of Sports Sciences, 2014 http://dx.doi.org/10.1080/02640414.2014.960881
Lower extremity kinematics of athletics curve sprinting
TOBIAS ALT1, KAI HEINRICH1, JOHANNES FUNKEN1 & WOLFGANG POTTHAST1,2 1
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany and 2ARCUS Sports Clinic, Pforzheim, Germany
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(Accepted 29 August 2014)
Abstract Curve running requires the generation of centripetal force altering the movement pattern in comparison to the straight path run. The question arises which kinematic modulations emerge while bend sprinting at high velocities. It has been suggested that during curve sprints the legs fulfil different functions. A three-dimensional motion analysis (16 high-speed cameras) was conducted to compare the segmental kinematics of the lower extremity during the stance phases of linear and curve sprints (radius: 36.5 m) of six sprinters of national competitive level. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. During the prolonged left stance phase (left: 107.5 ms, right: 95.7 ms, straight: 104.4 ms) the maximum values of ankle eversion (left: 12.7°, right: 2.6°, straight: 6.6°), hip adduction (left: 13.8°, right: 5.5°, straight: 8.8°) and hip external rotation (left: 21.6°, right: 12.9°, straight: 16.7°) were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (eversion–adduction strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics. This helps to increase the understanding of nonlinear human bipedal locomotion, which in turn might lead to improvements in athletic performance and injury prevention. Keywords: sprint kinematics, joint angles, eversion, adduction, external rotation
1. Introduction In contrast to the linear run, the sprint along a bend track has attracted little attention in sports sciences although its portion is about 58% when competing in sprint distances above 100 m (Meinel, 2008). Especially when competing distances from 200 to 400 m this occurs with high velocities of more than 9 m · s–1 (Churchill, Salo, & Trewartha, 2011, 2012). Since it is suggested that in curve sprints the reorientation of the body is accompanied by three-dimensional changes in joint angles of the lower extremity especially with regard to the horizontal and transversal plane (Hamill, Murphy, & Sussman, 1987; Ishimura & Sakurai, 2010; Smith, Dyson, Hale, & Janaway, 2006), it can be deduced that two-dimensional motion analyses are not sufficient to generate a comprehensive understanding. A variety of studies suppose a symmetrical action of both legs during linear sprints (Kuitunen, Komi, & Kyrolainen, 2002; Mann & Hagy, 1980; Novacheck, 1998; Stafilidis & Arampatzis, 2007). However, Exell, Gittoes, Irwin, and Kerwin (2012) and Exell, Irwin, Gittoes, and Kerwin (2012) highlighted the individuality of asymmetry which was present in 39%
of kinematic and 23% of kinetic parameters analysed during maximal sprint running on a straight path. Other values failed to reach statistical significance due to large intra-limb individuality. During curve sprinting, asymmetric kinematic modulations (Chang & Kram, 2007; Hamill et al., 1987; Ishimura & Sakurai, 2010; Nemtsev & Chechin, 2010; Smith et al., 2006) seem to reduce the maximal sprinting velocity (Bezodis & Gittoes, 2008; Churchill et al., 2011, 2012; Greene, 1985; Luo & Stefanyshyn, 2012). Investigations reveal that this impairment might rise as the radius of curvature decreases (Jain, 1980). The negative effect of the bend track on further kinematic parameters such as a prolongation of both stance phases is presumed whereas the left ground contact time tends to be longer than the right one (Churchill et al., 2011, 2012; Ishimura & Sakurai, 2010; Usherwood & Wilson, 2005, 2006). As the moving direction of the athlete’s centre of mass cannot be influenced during the flight phase, the change of movement direction has to be realised during ground contact. It has been suggested that flight phases and step lengths might shorten during curve sprinting (Smith
Correspondence: Tobias Alt, Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Muengersdorf 6, 50933 Cologne, Germany. E-mail: [email protected] © 2014 Taylor & Francis
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et al., 2006) while the right step is assumed to be longer than the left step (Stoner & Ben-Sira, 1979). Biomechanical analyses of curve sprinting often deal with the question why its maximal velocity is lower than during linear sprints (Chang, Campbell, & Kram, 2001; Chang & Kram, 2007; Churchill et al., 2011, 2012). In contrast to a theoretical framework (Greene, 1985), which is based on the assumption that both legs act similarly during curved sprints, different functionalities of the inside and outside leg were assumed (Hamill et al., 1987; Ishimura & Sakurai, 2010; Nemtsev & Chechin, 2010; Smith et al., 2006). This should lead to restrictive propulsive mechanisms due to a stabilisation in the frontal and horizontal plane (Chang & Kram, 2007; Churchill et al., 2012), an uneven loading on biological tissues and thus to different muscular adaptations (Beukeboom, Birmingham, Forwell, & Ohrling, 2000). Since a limited three-dimensional description of track and field specific curve sprint kinematics is available (Churchill et al., 2011, 2012; Ishimura & Sakurai, 2010), this motor task and its related requirements are not well-understood. A better knowledge of the different movement pattern during curve sprinting could lead to potential performance improvement and better injury prevention. Therefore the question arises which kinematic modulations – compared to the straight path run – become apparent while bend sprinting at high velocities. Consequently, the purposes of this study are to identify differences of the three-dimensional joint kinematics between linear and curve sprinting and to describe the asymmetrical functionality of both legs during curve sprinting. Based on the current literature it was hypothesised that during sprints with equal velocity (1) stance times are prolonged during curve sprinting and (2) the inside and outside leg show different joint angles at hip, knee and ankle in all movement planes during curve sprinting and in comparison to linear sprints.
2. Methods 2.1. Experimental design To identify the effects of curved versus linear sprinting on general spatio-temporal parameters and kinematics of the lower extremity, this experimental cross-sectional single cohort study compared for linear and curved sprints stance time, flight time, step length and step frequency as well as lower extremity joint angles in all three movement planes. Sprinting movements were recorded using a three-dimensional motion analysis system. Joint angles were calculated using an inverse kinematic rigid-body-model. The radius of curvature was 36.5 m which represents the first lane of an IAAF 400 m standard track (Meinel, 2008).
2.2. Participant preparation Six male sprinters (age: 20.2 ± 2.6 years; height: 1.86 ± 0.06 m; mass: 76.3 ± 8.2 kg; 200 m personal best: 22.60 ± 0.33 s) of national competitive level gave their written consent to participate voluntarily in this study. At testing day they were healthy and without any physical complaint. During the testing procedure the participants wore their own sprint spikes. Anthropometric data were collected according to the multibody human model Dynamicus 7.0 (alaska® Dynamcius® 7.0, Institute of Mechatronics, Chemnitz, Germany). After an individual warm-up 32 spherical retro-reflective markers (Ø 13 mm, ILUMARK GmbH, Feldkirchen/Munich, Germany) were placed on anatomical landmarks (motion-marker) of the pelvis, thigh, shank, rearfoot and forefoot. The motion markers of the anatomical foot landmarks were placed on corresponding anatomical positions on the surface of the sprint spikes. Twenty-four additional markers on the upper extremity, trunk and head helped to determine the position and velocity of the centre of mass and had no influence on the calculation of the data of the lower extremity. 2.3. Technical setup and instrumentation Kinematic data were collected in a motion capture laboratory which was constructed on an indoor athletics track. They were determined using an infrared camera system (VICONTM, Oxford, UK) operating 16 infrared cameras (MX F40) at 250 Hz. The calibration volume (8 m long, 2 m wide and 2 m high) was placed tangentially in the summit of the curve. The bend track was marked with white adhesive tape. 2.4. Experimental protocol and data analysis All participants were asked to perform straight and curve sprints with a constant individual submaximal sprinting velocity which should be attained after an approach run of 40 m. In order to eliminate possible kinematic alterations due to different velocities (Arampatzis, Brüggemann, & Metzler, 1999; Hamill, Bates, Knutzen, & Sawhill, 1983), the athletes were asked to perform sprints at 90% of their perceived maximal linear sprint velocity. Sprinting velocities were monitored by two timing gates placed three metres apart in the middle of the calibration volume. Three valid trials for each sprinter per condition (linear, curve) each, where sprinting velocity was within a defined individual range (±0.2 m · s–1), were recorded. Kinematics were calculated with the aid of the human multi-body model Dynamicus® (Härtel & Hermsdorf, 2006). Each leg consists of four segments (thigh, lower leg, rearfoot and toe). The segments are connected with ball and socket
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Kinematics of curve sprinting joints with three degrees of freedom. Individual dimensions and inertial properties were determined by anthropometric measurements (body mass, body height, segment lengths, maximal and minimal segment circumferences). One trial was recorded while the participant was standing in an upright position to determine the neutral position of all joints. This static measurement served as reference for the following dynamic trials. All stride parameters were determined from kinematic data. The events touchdown and take-off were identified by the use of the “foot contact algorithm” recommended by Maiwald, Sterzing, Mayer, and Milani (2009). According to this algorithm step length was defined as the resultant distance in the horizontal plane (between the toes top markers) from touchdown of one foot till touchdown of the contra lateral foot, e.g. right step is from right till left touchdown. During flight phase the centre of mass moved in a linear fashion with respect to the ground. The time between touchdown and take-off of the same leg defined the stance time. Flight time was calculated as the time between takeoff of one leg to touchdown of the contra lateral leg. The reciprocal value of the time between touchdown of one leg and touchdown of the other leg described the step frequency. Velocity over a step was identified as mean horizontal velocity of the centre of mass after take-off of the respective foot. Descriptive and inferential statistics (mean ± S) were carried out over the performance variables as well as the minimal and maximal joint angles during stance phases under the four investigated conditions: left and right stance of linear and curve sprinting as mean values of individual athletes’ three trials. By means of a paired t-test (IBM SPSS Statistics 19, IBM Corporation, New York, USA) curve- (LL vs. CL, LR vs. CR) and side-specific effects (LL vs. LR, CL vs. CR) were analysed. Normal distribution (Kolmogorov–Smirnov test) was verified. An error probability (P) of under 5% represents a significant difference. Because of the small sample size statistical tendencies (P < 0.1) are also indicated. To underline the meaningfulness of the significant differences effect size (Cohen’s d) is reported. Besides the graphical presentation of averaged stance time normalised angle-time histories for all joints and movement planes during linear and curved sprinting (Figure 1) an angle–angle plot (Figure 2) emphasises the segmental interaction along a bend track in the frontal and transversal plane.
3. Results 3.1. Spatio-temporal parameters Table I lists the mean values and standard deviations of the step parameters. No statistical significance in
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sprinting velocity was found between linear and curve sprints (Table I). Flight time, step length and step frequency were not affected by the bend. The stance time of the inside leg during curve sprinting was significantly 11.8 ms (P = 0.000; d = 1.39) longer compared to the stance phase of the outside leg during curve sprinting. Both stance times during curve sprinting were different in relation to linear runs. The right side displayed a significant decrease of 8.2 ms (P = 0.001; d = 1.00), whereas the left side showed an increase by trend of 2.6 ms (P = 0.067; d = 0.29) (Table I). 3.2. Joint kinematics Figure 1 displays the averaged time normalised angle-time histories for all joints and movement planes during linear and curved sprinting. Table II shows the mean values and standard deviations of maximum and minimum angle excursions during the stance phase. The analysis of the left and right stance phase during linear sprints revealed no significant differences concerning the extreme values of the joint angles at the ankle, knee and hip (Table II). The left and right stance phase during curve sprinting showed significant differences in all three joints of the lower extremity. This similar segmental interaction occurred in the frontal as well as in the horizontal plane whereas the joint angles in the sagittal plane remained unchanged (Table II). The eversion angle of the left ankle joint was significantly 10.1° larger than the outside one (P = 0.021; d = 1.62). With regard to the hip joint the maximal adduction angle was larger during the left stance phase (P = 0.005; d = 2.13) (Table II). During the right stance phase peak external rotation of the ankle reached threefold values in comparison to the left one (P = 0.031; d = 1.31). The maximum internal rotation of the right knee was significantly higher compared to the left knee joint (P = 0.014; d = 0.76). Hip joint peak external rotation during left stance exceeded the values measured in the right hip by almost 9° (P = 0.033; d = 1.57). A difference by trend was found in the internal rotation suggesting higher angles in the right hip (Table II) (P = 0.074; d = 1.30). The comparison between linear and curve sprinting revealed significant kinematic modulations in the ankle and hip joint whereas the joint angles of the knee remained equal. In the left ankle the peak eversion angle in curve sprinting was twice as big (P = 0.037; d = 1.12) whereas the right stance phase showed lower values compared to the straight path run (P = 0.043; d = 0.83). During the left stance phase of curved sprints peak hip adduction was significantly greater (P = 0.004; d = 1.71). The
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Figure 1. Time histories (normalised stance phase) of the ankle, knee and hip angle in the sagittal (top row), frontal (middle row) and transversal plane (bottom row) under the four investigated conditions: curve inside (solid black line), curve outside (solid grey line), straight left (dashed black line) and straight right (dashed grey line).
Figure 2. Angle-to-angle relations (frontal and transversal plane) during curve sprinting (left: ankle joint, middle: knee joint, right: hip joint): curve inside (solid black line) and curve outside (solid grey line). The arrows indicate the direction during the stance phase.
right stance phases of linear runs showed larger ankle external rotation (P = 0.001; d = 0.87) and hip adduction angles (P = 0.026; d = 1.00) than the bend condition of the same leg (Table II). 4. Discussion The purpose of this study was to investigate the effect of curve sprinting on lower extremity kinematics for
the inside and outside leg in comparison to linear sprinting. Unlike in previous investigations (Churchill et al., 2011, 2012), the velocity was kept similar both in curve and straight sprinting in the current study. This eliminates the velocity-specific modulations (Arampatzis et al., 1999; Hamill et al., 1983). Instead the observed kinematic differences might be a result of the supplement force requirement in medio-lateral direction. Consequently, it was
Kinematics of curve sprinting Table I. Mean values, standard deviations (S) and 95% confidence intervals (CI) of kinematic data under the conditions linear left (LL), linear right (LR), curve left (CL) and curve right (CR).
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Velocity [m · s ] 95% CI [m · s–1] Step length [m] 95% CI [m] Stance time [ms] 95% CI [ms] Flight time [ms] 95% CI [ms] Step frequency [Hz] 95% CI [Hz]
LL
LR
CL
CR
9.24 ± 0.40 8.92−9.56 2.18 ± 0.11 2.09−2.27 104.9 ± 8.9(c) 97.8−112.0 131.2 ± 12.4 121.3−141.1 4.29 ± 0.25 4.09−4.49
9.25 ± 0.45 8.89−9.61 2.14 ± 0.12 2.04−2.24 103.9 ± 8.2d 97.3−110.5 127.0 ± 15.0 115.0−139.0 4.31 ± 0.24 4.12−4.50
9.26 ± 0.45 8.90−9.62 2.24 ± 0.10 2.16−2.32 107.5 ± 8.8(a) d 100.5−114.5 133.3 ± 8.7 126.3−140.3 4.13 ± 0.21 3.96−4.30
9.39 ± 0.25 9.19−9.59 2.24 ± 0.08 2.18−2.30 95.7 ± 8.2b c 89.2−102.3 135.7 ± 13.0 125.3−146.1 4.35 ± 0.23 4.17−4.53
Notes: a b c drepresent a significant difference (P < 0.05) with LL, LR, CL and CR, respectively. Tendencies (P < 0.1) are set in brackets.
Table II. Peak values, standard deviations [°] and 95% confidence intervals (CI) of the ankle, knee and hip joint under the conditions linear left (LL), linear right (LR), curve left (CL) and curve right (CR). LL
LR
CL
CR
Ankle Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Eversion [°] 95% CI [°] Inversion [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
26.2 ± 1.1 25.3−27.1 29.6 ± 6.3 24.6−34.6 6.7 ± 2.3c 4.9−8.5 9.3 ± 4.2 5.9−17.7 4.0 ± 2.0 2.4−5.6 6.9 ± 3.2 4.3−9.5
26.0 ± 1.7 24.6−27.4 30.0 ± 4.5 26.4−33.6 6.4 ± 4.0d 3.2−9.6 9.1 ± 2.4(d) 7.2−11.0 4.3 ± 3.7d 1.3−7.3 7.7 ± 4.0 4.5−10.9
26.8 ± 4.1 23.5−30.1 28.7 ± 5.4 24.4−33.0 12.7 ± 7.2a d 6.9−18.5 7.2 ± 6.4 2.1−12.3 2.4 ± 4.2d −1.0−5.8 6.6 ± 5.0 2.6−10.6
23.2 ± 6.0 18.4−28.0 29.5 ± 2.2 27.7−31.3 2.6 ± 5.1b c −1.5−6.7 10.4 ± 3.3(b) 7.8−13.0 7.3 ± 3.2b c 4.7−9.9 6.2 ± 2.9 3.9−8.5
Knee Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Abduction [°] 95% CI [°] Adduction [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
45.0 ± 4.2 41.6−48.4 18.2 ± 4.0 15.0−21.4 2.0 ± 3.7 −1.0−5.0 1.8 ± 3.0 −0.6−4.2 1.1 ± 2.9 −1.2−3.4 9.9 ± 4.1 6.6−13.2
44.8 ± 4.4 41.3−48.3 16.0 ± 2.0 14.4−17.6 2.8 ± 2.8 0.6−5.0 0.6 ± 3.1 −1.9−3.1 1.0 ± 3.8 −2.0−4.0 8.9 ± 4.2(d) 5.5−12.3
43.9 ± 6.4 38.8−49.0 17.1 ± 2.8 14.9−19.3 2.1 ± 3.3 −0.5−4.7 2.4 ± 3.7 −0.6−5.4 1.9 ± 5.1 −2.2−6.0 8.8 ± 5.3d 4.6−13.0
48.8 ± 7.1 43.1−54.5 18.6 ± 7.3 12.8−24.4 3.3 ± 2.3 1.5−5.1 −0.9 ± 2.8 −3.1−1.3 0.3 ± 4.0 −2.9−3.5 12.8 ± 5.2(b) 8.6−17.0
Hip Flexion [°] 95% CI [°] Extension [°] 95% CI [°] Abduction [°] 95% CI [°] Adduction [°] 95% CI [°] External rotation [°] 95% CI [°] Internal rotation [°] 95% CI [°]
25.2 ± 6.7 19.8−30.6 29.2 ± 3.5 26.4−32.0 7.1 ± 2.2 5.3−8.9 7.7 ± 3.8c 4.7−10.7 19.0 ± 4.1(b) 15.7−22.3 −1.5 ± 3.2 −4.1−1.1
25.6 ± 5.1 21.5−29.7 29.8 ± 3.3 27.2−32.4 8.1 ± 2.4 6.2−10.0 9.8 ± 4.2d 6.4−13.2 14.3 ± 4.1(a) 11.0−17.6 1.5 ± 4.0 −1.7−4.7
26.3 ± 5.4 22.0−30.6 31.5 ± 3.3 28.9−34.1 4.8 ± 3.0 2.4−7.2 13.8 ± 3.3a d 11.2−16.4 21.6 ± 6.7d 16.2−27.0 −4.6 ± 4.3(d) −8.0−−1.2
24.5 ± 4.4 21.0−28.0 27.6 ± 8.2 21.0−34.2 7.5 ± 4.4 4.0−11.0 5.5 ± 4.4b c 2.0−9.0 12.9 ± 4.1c 9.6−16.2 2.1 ± 5.9(c) −2.6−6.8
c
Notes: a b c drepresent a significant difference (P < 0.05) with LL, LR, CL and CR, respectively. Tendencies (P < 0.1) are set in brackets.
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assumed that the observed changes in segmental interaction of the lower extremity can be declared as curvespecific. If the selected sub-maximal velocity during linear sprints included a change in movement, behaviour is unknown. It has been hypothesised that during sprints with equal velocity (1) stance times are prolonged during curve sprinting and (2) the inside and outside leg show a different kinematic behaviour. Due to methodological differences in sprinting velocity and experimental setup the present results of the temporal–spatial parameters are contrary to previous studies (Smith et al., 2006; Stoner & Ben-Sira, 1979). Flight time, step length and step frequency did not differ during fixed-velocity curve sprints in comparison to linear ones. However, the left stance time during curve sprinting exceeded the right one significantly by 11.8 ms (P = 0.000; d = 1.39), a finding which is in accordance to Ishimura and Sakurai (2010) (CL: 125 ms; CR: 112 ms) and holds true during maximal curve sprints as well (Churchill et al., 2011). Therefore, hypothesis 1 is confirmed for the left leg and declined for the right. It has to be pointed out, that in curve running there are considerable differences between the velocity of the centre or mass and the product of step frequency and step length (Table I). The path the centre of mass travels during one step is not identical to the distance between point of touchdown of one leg and the point of the subsequent touchdown of the contralateral leg. This effect should be more pronounced in curve running in comparison to linear running, which still has to be confirmed by future studies. The analysis of the linear sprints indicated a similar segmental interaction of the lower extremity during the stance phase. Thus, the right and left stance phase during linear sprinting required similar demands to the musculo-skeletal system and motor control which confirms the current knowledge of lower extremity function during linear sprints (Kuitunen et al., 2002; Stafilidis & Arampatzis, 2007). Curve sprinting poses a high load to the sprinter’s foot muscles as a change in direction has to take place at high velocities within short stance times. During the stance phase of the inside foot a high ankle eversion occurred (CL: 12.7°; CR: 2.6°; P = 0.021; d = 1.62). According to Clarke, Frederick, and Hamill (1984) an eversion of almost 13° reaches unphysiological limits which might lead to injuries if it emerges repeatedly (Beukeboom et al., 2000). Nevertheless, the presented peak eversion angle did not reach by far the extent measured by Hamill et al. (1987) (CL: 22.3°; CR: 12.5°) and Smith et al. (2006)
(CL: 34.0°; CR: 6.7°). This discrepancy can be originated in different testing conditions (rearfoot runners, smaller radii). The present results indicated a different foot-planting pattern while bend sprinting (Figure 1). The right foot displayed an initial external rotation angle of 1.0° whereas the left foot was internally rotated (4.6°). During the stance phase, peak external rotation in the right ankle reached threefold values compared to the inside foot (CL: 2.4°; CR: 7.3; P = 0.031; d = 1.31) (Table II). Research about angular kinematics of the knee in the frontal and transversal plane is missing. Consequently, the significant higher internal rotation angle of the right knee (CL: 8.8°; CR: 12.8°; P = 0.014; d = 0.76) is a new finding leading to the idea that during the right stance phase transversal angular modulations are of special importance. As sagittal plane kinematics did not differ between linear and curved sprints the present results conflict with previous investigations. They claimed that knee flexion becomes greater during curve sprinting and that this amortisation increases with smaller radii of curvature (Churchill et al., 2011). This contradiction might be due to the fact that maximal sprinting velocities were investigated (Churchill et al., 2011). In the present case the peak hip adduction angle of the left leg reached more than twofold values (CL: 13.8°; CR: 5.5°; P = 0.005; d = 2.13) in comparison to the outside leg indicating a greater inward lean of the inside shank. This result is in accordance with previous findings (Churchill et al., 2011; Ishimura & Sakurai, 2010). However, in both studies the amount of the peak adduction was smaller (7.4° and 10.6°, respectively) probably because larger radii of curvature were investigated. Peak hip external rotation during left stance exceeded the values of the right hip (CL: 21.6°; CR: 12.9°; P = 0.033; d = 1.57). Since the transversal modulations induced by the bend have not been extensively analysed yet this kinematic feature is a new finding. During the prolonged left stance phase during curved sprints the supporting leg displayed high peak values of the ankle eversion, the hip adduction and the hip external rotation. Concerning the left knee joint no kinematic modulations became apparent. In contrast, right stance phase of curved sprints was characterised by high peak values of the ankle external rotation and the knee internal rotation. Additionally, a significantly lower maximum eversion angle of the ankle and hip adduction angle occurred. In summary, hypothesis 2 is accepted for frontal and transversal plane kinematics, but declined for the sagittal plane.
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Kinematics of curve sprinting In contrast to the comparable segmental interaction during the straight path run, curve sprinting posed different requirements on the inside and outside leg demonstrated in varying kinematic modulations (Figure 2). Several authors (Bezodis & Gittoes, 2008; Chang & Kram, 2007; Churchill et al., 2011, 2012; Hamill et al., 1987; Smith et al., 2006) suggested a different technique during curved sprints to generate the necessary centripetal force, but direct evidence was missing. The present kinematic analysis of step parameters and joint angles of the lower extremity during the stance phases supports the assumption that the inside and outside leg seem to fulfil different tasks during curve sprinting. An explanatory approach of the identified effects could be the fact that a greater adduction angle has to occur in the left hip if touchdown occurs with equal knee flexion, comparable height of the centre of mass and similar tilted hip axis (Churchill et al., 2011; Ishimura & Sakurai, 2010). Consequently, the inclination of the inside shank has to be greater (Hamill et al., 1987; Nemtsev & Chechin, 2010; Smith et al., 2006). During the left stance phase this inner inclination of the sprinter’s body leads to a significantly longer stance time and a greater eversion angle of the ankle. Recent research (Bezodis & Gittoes, 2008; Chang et al., 2001; Chang & Kram, 2007; Churchill et al., 2012; Luo & Stefanyshyn, 2012) pointed out that the inside leg has performance-limiting influence and thus is responsible for the significantly lower maximal sprint velocity during curved sprints. Based on the present study this question cannot be answered as the results rely on equal submaximal sprinting velocities. However, it can be supposed that the propulsion of the inside leg may be restricted since the centripetal force increases with the power of two with the sprinting velocity and the necessary stabilisation in the frontal and transversal plane becomes critical (Chang et al., 2001; Chang & Kram, 2007). Additionally the segmental orientation of the inside leg in curve sprinting is quite complex with an intensive external hip rotated combined with adduction, while the ankle is everted (Figure 2). This might be disadvantageous in terms of motor control and muscle lengths and therefore limits the propulsive capacity during left stance. Those limitations might rise if the radius of curvature decreases (Jain, 1980). This question may be answered by a kinetic analysis of the ankle, knee and hip joint moments occurring during the stance phase. During its stance phase the right leg underlies a longitudinal twisting as a prominent external rotation of the ankle and a high internal rotation angle of the knee occur simultaneously (Figure 1). In accordance with the lower external rotation angle of the hip this segmental interaction
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in the late right stance phase allows the push-off in the new direction. Overall, sprinting is only possible if the necessary centripetal force is generated. This additional task results in an inclination of the athlete’s body and several changes of the joint angles of the lower extremity, primarily in the frontal and transversal plane. The present three-dimensional motion analysis of both stance phases suggests that the sprinter applies an eversion–adduction strategy during the stance phase of the inside leg during curve sprinting. This becomes apparent as changes in the ankle and hip angles especially take place in the frontal plane compared to linear runs. Meanwhile, the outside leg accounts for several angular modifications in the transversal plane which may be summarised as rotational mechanism. This underlines the different functionality of inside and outside leg during curve sprinting (Figure 2). The present study aimed to establish discrete values of kinematic parameters during linear and curve sprints of equal sub-maximal velocity. It was found that the movement pattern during straight path run was comparable whereas the segmental action of curved locomotion was different. These results impose a more explicit research of asymmetrical kinematic behaviour during human bipedal locomotion which was beyond the scope of our investigation. The application of the symmetry angle method of Zifchock, Davis, Higginson, and Royer (2008) may demonstrate if the observed kinematic differences during curve sprinting are in fact proof of an asymmetrical technique. As Exell, Gittoes, Irwin, and Kerwin (2012) and Exell, Irwin, Gittoes, and Kerwin (2012) indicated that a high intra-limb individuality during sprint running causes misleading results if it is not included in asymmetry analyses, it is not appropriate to interpret the present results as symmetrical or asymmetrical kinematic behaviour. In general, further research is needed to extend the segmental interaction of both legs during their stance phase while running along a bend track. Additional information about the ground reaction forces and the joint moments based on a larger sample size will improve the understanding of the curve sprinting technique and its underlying propulsive and stabilising mechanisms. This will help to understand the functioning of both legs and to quantify the impact on biological tissues. Results of the ankle joint should be regarded with caution as the retro-reflective markers were attached on the shoes and not on the skin which might lead to small variations. Additional investigation is needed to prove if larger radii of curvature might have a
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positive effect on lower extremity function during curve sprinting.
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5. Conclusion This study offers an insight into the different technique during curve sprinting. Peak joint angles substantially differed in the frontal and transversal plane whereas sagittal plane kinematics remained unchanged. Temporal–spatial parameters did not show any significant differences except stance time. During the prolonged left stance phase the maximum values of ankle eversion, hip adduction and hip external rotation were significantly higher. The inside leg seemed to stabilise the movement in the frontal plane (adduction–eversion strategy) whereas the outside leg provided and controlled the motion in the horizontal plane (rotation strategy). These results extend the principal understanding of the effects of curve sprinting on lower extremity kinematics and may help to improve athletic performance. This comprehensive understanding of lower extremity kinematics during nonlinear human locomotion may in the long run be helpful both for coaches and athletes. It serves to understand the different technique of the legs during curve sprinting facilitating the movement perception as well as feedback of the coach and thus the technical improvement of the athlete. This can contribute to improve athletic performance by evaluating curve-specific technical and conditioning training programmes. Additionally, these findings may support physiotherapists in injury prevention by implementing explicit strengthening and mobility exercises of the foot muscles (Beukeboom et al., 2000).
Funding This study was supported by Nike Inc.
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