Journal of Sport Rehabilitation, 2014, 23, 296-299 http://dx.doi.org/10.1123/jsr.2013-0025 © 2014 Human Kinetics, Inc.
Effect of Foam Rolling and Static Stretching on Passive Hip-Flexion Range of Motion Andrew R. Mohr, Blaine C. Long, and Carla L. Goad Context: M any athletes report that foam rollers help release tension in their m uscles, thus resulting in greater range o f m otion (ROM ) w hen used before stretching. To date, no investigators have exam ined foam rollers and static stretching. Objective: To determ ine if foam rolling before static stretching produces a significant change in passive hip-flexion ROM . Design: Controlled laboratory study. Setting: Research laboratory. Participants: 40 subjects w ith less than 90° o f passive hip-flexion ROM and no low er-extrem ity injury in the 6 mo before data collection. Interventions: D uring each o f 6 sessions, subjects’ passive hip-flexion ROM was m easured before and im m ediately after static stretching, foam rolling and static stretching, foam rolling, or nothing (control). To m inim ize accessory m ovem ent o f the hip and contralateral leg, subjects lay supine with a strap placed across their hip and another strap located over the uninvolved leg ju st superior to the patella. A bubble inclinom eter was then aligned on the thigh o f the involved leg, w ith w hich subjects then perform ed hip flexion. Main Outcome Measure: C hange in passive hip-flexion ROM from the preintervention m easure on day 1 to the postintervention m easure on day 6. Results: There was a significant change in passive hip-flexion ROM regardless o f treatm ent (F 3i17 = 8.06, P = .001). Subjects receiving foam roll and static stretch had a greater change in passive hip-flexion ROM com pared with the static-stretch (P = .04), foam -rolling (P = .006), and control (P = .001) groups. Conclusions: O ur results support the use o f a foam roller in com bination w ith a static-stretching protocol. If tim e allow s and m axim al gains in hip-flexion ROM are desired, foam rolling the ham strings m uscle group before static stretching w ould be appropriate in noninjured subjects who have less than 90° o f ham string ROM.
Keywords: self-m yofascial release, flexibility, ROM Increasing flexibility through static stretching is com m on am ong athletes and recreationally active people. It is reported that static stretching results in greater flex ibility and range o f m otion (R O M )1-10 and reduces the risk o f injury." It is also reported, however, that static stretching before activity may low er perform ance and increase energy dem and12’13 or has no beneficial effect on injury prevention.14 B ased on these conflicting results, an increasingly popular technique that m ay be incorporated w ith static stretching is self-m yofascial release (SM R ). C laim s regarding the use o f SM R suggest that it im proves ROM through autogenic inhibition w here the m assage also increases blood flow and reduces adhesions and scar tissue.15 Previous investigations on SM R are lim ited. In 1 study it was reported that ham string flexibility was not influenced by SM R through the use o f foam rolling over an 8-w eek period.16T hat study, however, did not com pare foam rollers with a regular stretching protocol. Mohr is with the Dept of Sport Sciences, Iowa Western Com munity College, Council Bluffs, IA. Long is with the Dept of Athletic Training, Central Michigan University, Mt Pleasant, MI. Goad is with, the Dept of Statistics, Oklahoma State University, Stillwater, OK. Address author correspondence to Blaine Long at [email protected]. 296
Foam rollers are com m only used as an adjunct to a stretching program or in som e cases may serve as a replacem ent o f regular static stretching. G iven this, it is assum ed that the com bination o f SM R through the use o f foam rollers and static stretching would increase ROM. T he purpose o f this study therefore was to determ ine if a change in passive hip-flexion ROM occurs in the ham string m uscle group after 6 consecutive days o f static stretching and SM R with a foam roller.
Methods Subjects Forty subjects (static stretching: n = 10, age 22.00 ± 3.80 y, height 171.32 ± 5.44 cm , m ass 78.14 ± 14.44 kg; foam rolling: n = 10, age 21.00 ± 2.21 y, height 173.20 ± 6.31 cm , m ass 74.60 ± 15.64 kg; foam rolling and static stretching: n = 10, age 21.20 ± 2.44 y, height 167.64 ± 8.55 cm , m ass 68.05 ± 10.32 kg; control: n = 10, age 20.80 ± 2.70 y, height 169.42 ± 8.80 cm , m ass 72.86 ± 13.30 kg) volunteered to participate in this investigation. Before participation, each subject com pleted a healthhistory questionnaire to ensure that they had no previous history o f low er-extrem ity or spine injury, involvement in any low er-extrem ity flexibility program , any injury
Stretching
or disease that w ould affect their ham string flexibility, or circulation problem s. Subjects w ere also screened to ensure that they were recreationally active as defined by engaging in physical activity 1 to 5 h/w k.17 Subjects were also screened to determ ine if they had lim itations in ham string flexibility before the study. Lim itation in ham string flexibility was defined by having hip-flexion ROM less than 90° as m easured by a passive straight-leg-raise test. All subjects provided w ritten inform ed consent, and the study was approved by the institutional review board.
Study Analysis A 2 x 4 x 6 factorial with repeated m easures on all factors guided data collection. The independent variables were tim e (pretreatm ent and posttreatm ent), treatm ent (static stretching only [SS], foam rolling only [FM], foam rolling and static stretching [FR/SS], and control), and day (1, 2, 3, 4, 5, and 6). The dependent variable was change in passive hip-flexion ROM from the pretreatm ent m easure on day 1 to the posttreatm ent m easure on day 6.
Instruments We m easured passive hip-flexion ROM w ith a Baseline bubble inclinom eter (Fabrication Enterprises, Inc, W hite Plains, NY). Each m easure was taken from the subject’s dom inant leg (ie, the leg with w hich he or she kick a ball) w hile he or she lay on a padded table in a supine posi tion. The use o f bubble inclinom eters is reported to have an intrarater reliability that ranges from .92 to .97.1819 For each hip-flexion ROM m easure, we used two 8-cm-wide x 213-cm-long belts with the slack removed to minimize any accessory movement of the pelvis and non dominant leg. All foam-rolling procedures were completed with a 15-cm x 91-cm Cando EVA foam roller (Chatta nooga Group, Chattanooga, TN). During all foam rolling we used a digital metronome (Evets Corp, Camarillo, CA) set at 60 beats/min to maintain a consistent speed.
297
consistency of each measure, the center point between the A SIS and the superior pole o f the patella on the subject’s dom inant leg was marked with a pen. We then placed 1 end o f the inclinom eter on the mark and passively flexed the subject’s hip to the point o f discom fort to establish the baseline ROM m easure (Figure 1). Subjects receiving SS rem ained in a supine position on the padded table, where 3 consecutive passive stretches were perform ed w hile their nondom inant leg and ASIS rem ained secured to the table. For each stretch, the inves tigator moved the subject’s leg to the point o f discom fort w ithout pain. The stretch was then held for 1 m inute in duration with 30-second rests betw een stretches. Subjects assigned to receive the F R placed the foam roller betw een their ischial tuberosity and a hard surface (ie, floor) with their legs m aintained in an extended posi tion, keeping their ankles relaxed and oriented upward (Figures 2 and 3). Subjects were then instructed to support their body w eight with their arms extended but to allow as m uch pressure between the ham string m uscle group and the foam roller. Subjects then actively moved the foam roller at a cadence of 1 second inferior (ischial tuberosity to popliteal fossa) and 1 second superior (popliteal fossa to ischial tuberosity) as determ ined with the m etronom e. The foam-rolling protocol included three 1-minute repeti tions with a 30-second break between repetitions to allow subjects to rest their arm s. Subjects random ly assigned to the FR/SS group perform ed the same foam -rolling protocol as those in the FR group and w ere stretched in the same m anner as those in the SS group. Immediately after each treatment, passive hip-flexion ROM measures were repeated. Those in the control group received the same hip-flexion-ROM measures at the same tim e interval as those in the FR/SS group, w hich was approximately 5 minutes after the preintervention measure.
Statistical Analysis We calculated the average change and standard error in passive hip-flexion ROM. We then used the G LIM M IX
Testing Procedures Subjects reported to the laboratory on 6 days separated by at least 48 hours dressed in shorts and a T-shirt. On arrival, they were random ly assigned to 1 o f the 4 treat ment groups by selecting a num ber 1, 2, 3, or 4 from a container. Subjects assigned to receive FR and FR/SS were allowed to fam iliarize them selves with the foam roller. Fam iliarization consisted of giving the subjects specific instructions on how to perform foam rolling and a dem onstration by the first author to ensure correct technique. We did not allow subjects to practice on the foam roller, as this may have influenced the results. Subjects were then positioned supine on a padded table where their nondom inant leg and hips were secured with the straps. O ne belt was applied over the subject’s nondom inant thigh, ju st superior to the patella, and the other strap was applied over each anterosuperior iliac spine (ASIS; Figure 1). U sing the bubble inclinom eter, pretreatm ent hipflexion ROM m easures were then com pleted. To ensure
Figure 1 — Measurement procedures for hip-flexion range of motion. Care was taken to ensure that the contralateral leg and pelvis were secured to the table with individual straps.
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procedure for general linear mixed models20 to perform a 2-way ANCOVA (time x treatment), with change in ROM between the initial passive hip-flexion ROM mea sure on day I and the last (posttreatment) hip-flexion ROM measure on day 6 as the dependent variable. We used the pretreatment mean between treatment groups as the covariate. Independent t tests were then used to isolate individual differences. Results were considered statistically significant at an alpha level of P < .05.
Confidence intervals (95%) were calculated for passive hip-flexion range of motion. Between-groups effect sizes were calculated against the control using Cohen d.2[ We used the Statistical Analysis System (SAS, Cary, NC) to analyze all data.
Results Descriptive statistics (mean ± SE) for the change in pas sive hip flexion, 95% confidence intervals, and effect sizes are summarized in Table 1. There was a significant change in passive hip-flexion ROM regardless of treatment (F317 = 8.06, P =.001). Subjects receiving FR/SS had a greater change in passive hip-flexion ROM compared with the SS (rl7 = -2.07, P = .04), FR (r ,g = 3.11, P = .006), and control (f13 = 5.00, P= .001). There were no significant differences between any of the other treatments (P>.09).
Discussion
Figure 2 — Starting-position foam roller at the ischial tuber
osity.
Figure 3 — Ending-position foam roller at the inferior portion of the popliteal fossa.
Our objective was to determine if foam rolling performed before static stretching would influence passive hipflexion ROM. We hypothesized that since static stretching has been reported to improve hip-flexion ROM, 1-4 6-1017 the addition of foam rolling with its claimed benefits of improving flexibility15 would increase passive hip-flexion ROM more than static stretching or foam rolling alone. Oftentimes clinicians incorporate a therapeutic intervention before warm-up activities. 15 We decided to use the foam roller before a static-stretching protocol to act as a warm-up for the hamstring muscle group. With a greater change in passive hip-flexion ROM observed in those receiving FR/SS, it appears that the combination of the foam roller before the static stretching resulted in therapeutic benefits similar to those reported by others who have examined therapeutic interventions prior to static stretching.3-4 The greater change in passive hip-flexion ROM observed in the FR/SS group as compared with the SS, FR, and control groups is likely due to increases in temperature. Although it was not possible to measure surface or intramuscular temperature during the foam rolling procedure, it is likely that the constant movement before static stretching increased intramuscular tissue temperature and blood flow, both of which are reported to increase the viscoelastic properties of muscle.22 Another possible explanation is the thixotropic property reported
Table 1 Average Change in Passive Hip-Flexion Range of Motion From the Pretreatment Measure, 95% Confidence Intervals, and Calculated Effect Size Tim e
Change from baseline Confidence interval Between-groups effect size
Static stretch only
Foam roller + static stretch3
Foam roller only
Control
12.26 ±4.21 (2.62,21.83) 2.63
23.55 ± 3.53 (15.57,31.53) 7.06
6.88 ± 3.97 (-2.07, 15.84) 1.81
3.74 ± 1.81 (-.037, 7.85) —
Note: These average changes were based on the unequal variance between pretreatment ranges of motion (n = I0 subjects/treatment; mean ± SE). a Foam roller + static stretch > static stretch only, foam roller only, and control, postintervention; P < .05.2
Stretching
in muscle and fascia.23 It is suggested that changes in the thixotropic properties of muscle and fascia decrease tissue viscosity. As a result, tissue becomes less resistant when a stretch is applied, resulting in greater hip-flexion ROM. Few investigators have studied the use of a foamroller treatment. In 1 study it was reported that ROM measures did not change after a foam-rolling treatment when subjects in the control group also presented with increased ROM.16 Although our subject demographics and foam-rolling procedure (ie, three 1-min repetitions totaling 6 min) were similar, we secured subjects’ hip and pelvis to the table to prevent any accessory motion and we measured passive hip-flexion ROM instead of active knee-extension ROM. By securing the subjects’ hip and nondominant leg with straps with a different method of measuring ROM, it appears that more application times or how the measures are taken influenced hip-flexion ROM. The results of this study can only be limited to indi viduals who have less than 90° of passive hip-flexion ROM in their dominant leg. Future studies involving a foam roller applied to both hamstring muscle groups before or after a static-stretching protocol may present different results. Clinically, the results of this study can be used to support the use of a foam roller in combination with a 2-week static-stretching protocol. Our results showed an increase in hip-flexion ROM across all treatment groups, with the greatest gains in the foam-rolling and static stretching group. Clinicians therefore should incorporate a foam-rolling protocol of the hamstrings before static stretching in uninjured subjects who have less than 90° of hamstring flexibility.
References 1. Ross MD. Effect of a 15-day pragmatic hamstring stretch ing program on hamstring flexibility and single hop for dis tance test performance. Res Sports Med. 2007;15(4):271281. PubMed doi: 10.1080/15438620701693298 2. Davis DS, Ashby PE, McCale KL, McQuain JA, Wine JM. The effectiveness of 3 stretching techniques on ham string flexibility using consistent stretching parameters. J Strength Cond Res. 2005; 19( 1):27—32. PubMed 3. de Weijer VC, Gorniak GC, Shamus E. The effect of static stretch and warm-up exercise on hamstring length over the course of 24 hours. J Orthop Sports Phys Ther. 2003;33( 12):727—733. PubMed doi: 10.2519/ jospt.2003.33.12.727 4. O’Sullivan K, Murray E, Sainsbury D. The effect of warm up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects. BMC Musculoskelet Disord. 2009;10:37. PubMed doi: 10.1186/14712474-10-37 5. Depino GM, Webright WG, Arnold BL. Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol. JAthl Train. 2000;35( 1):56—59. PubMed 6. Bandy WD, Irion JM, Briggler M. The effect of time and frequency of static stretching on flexibility of the hamstring muscles. Phys Ther. 1997;77( 10): 1090—1096. PubMed
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7. Russell PJ, Decoster LC, Enea D. Effects of gastrocne mius, hamstrings, and combined stretching programs on knee extensibility. Athl Train Sports Health Care. 2010;2(2);67—73. doi: 10.3928/19425864-20100226-06 8. Decoster LC, Scanlon RL, Horn KD, Cleland J. Standing and supine hamstring stretching are equally effective. J Athl Train. 2004;39(4):330-334. PubMed 9. Cipriani D, Abel B, Pirrwitz D. A comparison of two stretching protocols on hip range of motion: implications for total daily stretch duration. J Strength Cond Res. 200.3; 17(2):274—278. PubMed 10. Ford G, Mazzone MA. Taylor K. The effect of 4 different durations of static hamstring stretching on passive knee extension range of motion in healthy subjects. J Sport Rehabil. 2005;14(2):95-106. 11. Jamtvedt G, Herbert RD, Flottorp S, et al. A pragmatic randomised trial of stretching before and after physi cal activity to prevent injury and soreness. Br J Sports Med. 2010:44(14): 1002-1009. PubMed doi: 10.1136/ bjsm.2009.062232 12. Wilson JM, Hornbuckle LM, Kim JS, et al. Effects of static stretching on energy cost and running endurance per formance. J Strength Cond Res. 2010;24(9):2274-2279. PubMed doi: 10.1519/JSC.0b013e3181 b22ad6 13. Knudson DV, Magnusson P, McHugh M. Current issues in flexibility fitness. Pres Counc Phys Fit Sports. 2000:3:1-6. 14. Witvrouw E, Mahieu NN, Danneels LA, McNair P. Stretch ing and injury prevention: an obscure relationship. Sports Med. 2004;34:443-449. PubMed doi: 10.2165/00007256200434070-00003 15. Robertson M. Self-Myofascial Release Purpose, Methods and Techniques. Indianapolis, IN: Indianapolis Fitness and Sports Training; 2008. 16. Miller JK, Rockey AM. Foam rollers show no increase in the flexibility of the hamstring muscle group. UW-L J Undergrad Res. 2006;IX: 1-4. 17. Marek SM, Cramer JT, Fincher AL, et al. Acute effects of static and proprioceptive neuromuscular facilitation stretching on muscle strength and power output. J Athl Train. 2005;40(2):94-103. PubMed 18. Hsieh CY, Walker JM, Gilis K. Straight-leg-raising test: com parison of three instrum ents. Phys Ther. 1983;63:1429-1433. PubMed 19. Davis DS, Quinn RO, Whiteman CT, Williams JD, Young CR. Concurrent validity of four clinical tests used to m easure ham string flexibility. J Strength Cond Res. 2008;22(2):583-588. PubMed doi: 10.1519/ JSC.ObOl 3e31816359f2 20. SAS/STAT 9.2 User Guide. Overview: GLIMMIX Proce dure. 2nd ed. 2010. Accessed June 10, 2013. 21. Cohen J. Statistical Power Analysis fo r the Behavioral Sciences. 2nd ed. Hillsdale, NJ: Lawrence Erlbaum; 1988. 22. Knight CA, Rutledge CR, Cox ME, Costa MA, Hall SJ. Effect of superficial heat, deep heat, and active exercise warm-up on the extensibility of the plantar flexors. Phys Ther. 2001 ;81 (6): 1206—1214. PubMed 23. Sefton J. Myofascial release for athletic trainers, part I: theory and session guidelines. Athl Ther Today. 2004:9(1 ):48^I9.
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Effect of Foam Rolling and Static Stretching on Passive Hip-Flexion Range of Motion Andrew R. Mohr, Blaine C. Long, and Carla L. Goad Context: M any athletes report that foam rollers help release tension in their m uscles, thus resulting in greater range o f m otion (ROM ) w hen used before stretching. To date, no investigators have exam ined foam rollers and static stretching. Objective: To determ ine if foam rolling before static stretching produces a significant change in passive hip-flexion ROM . Design: Controlled laboratory study. Setting: Research laboratory. Participants: 40 subjects w ith less than 90° o f passive hip-flexion ROM and no low er-extrem ity injury in the 6 mo before data collection. Interventions: D uring each o f 6 sessions, subjects’ passive hip-flexion ROM was m easured before and im m ediately after static stretching, foam rolling and static stretching, foam rolling, or nothing (control). To m inim ize accessory m ovem ent o f the hip and contralateral leg, subjects lay supine with a strap placed across their hip and another strap located over the uninvolved leg ju st superior to the patella. A bubble inclinom eter was then aligned on the thigh o f the involved leg, w ith w hich subjects then perform ed hip flexion. Main Outcome Measure: C hange in passive hip-flexion ROM from the preintervention m easure on day 1 to the postintervention m easure on day 6. Results: There was a significant change in passive hip-flexion ROM regardless o f treatm ent (F 3i17 = 8.06, P = .001). Subjects receiving foam roll and static stretch had a greater change in passive hip-flexion ROM com pared with the static-stretch (P = .04), foam -rolling (P = .006), and control (P = .001) groups. Conclusions: O ur results support the use o f a foam roller in com bination w ith a static-stretching protocol. If tim e allow s and m axim al gains in hip-flexion ROM are desired, foam rolling the ham strings m uscle group before static stretching w ould be appropriate in noninjured subjects who have less than 90° o f ham string ROM.
Keywords: self-m yofascial release, flexibility, ROM Increasing flexibility through static stretching is com m on am ong athletes and recreationally active people. It is reported that static stretching results in greater flex ibility and range o f m otion (R O M )1-10 and reduces the risk o f injury." It is also reported, however, that static stretching before activity may low er perform ance and increase energy dem and12’13 or has no beneficial effect on injury prevention.14 B ased on these conflicting results, an increasingly popular technique that m ay be incorporated w ith static stretching is self-m yofascial release (SM R ). C laim s regarding the use o f SM R suggest that it im proves ROM through autogenic inhibition w here the m assage also increases blood flow and reduces adhesions and scar tissue.15 Previous investigations on SM R are lim ited. In 1 study it was reported that ham string flexibility was not influenced by SM R through the use o f foam rolling over an 8-w eek period.16T hat study, however, did not com pare foam rollers with a regular stretching protocol. Mohr is with the Dept of Sport Sciences, Iowa Western Com munity College, Council Bluffs, IA. Long is with the Dept of Athletic Training, Central Michigan University, Mt Pleasant, MI. Goad is with, the Dept of Statistics, Oklahoma State University, Stillwater, OK. Address author correspondence to Blaine Long at [email protected]. 296
Foam rollers are com m only used as an adjunct to a stretching program or in som e cases may serve as a replacem ent o f regular static stretching. G iven this, it is assum ed that the com bination o f SM R through the use o f foam rollers and static stretching would increase ROM. T he purpose o f this study therefore was to determ ine if a change in passive hip-flexion ROM occurs in the ham string m uscle group after 6 consecutive days o f static stretching and SM R with a foam roller.
Methods Subjects Forty subjects (static stretching: n = 10, age 22.00 ± 3.80 y, height 171.32 ± 5.44 cm , m ass 78.14 ± 14.44 kg; foam rolling: n = 10, age 21.00 ± 2.21 y, height 173.20 ± 6.31 cm , m ass 74.60 ± 15.64 kg; foam rolling and static stretching: n = 10, age 21.20 ± 2.44 y, height 167.64 ± 8.55 cm , m ass 68.05 ± 10.32 kg; control: n = 10, age 20.80 ± 2.70 y, height 169.42 ± 8.80 cm , m ass 72.86 ± 13.30 kg) volunteered to participate in this investigation. Before participation, each subject com pleted a healthhistory questionnaire to ensure that they had no previous history o f low er-extrem ity or spine injury, involvement in any low er-extrem ity flexibility program , any injury
Stretching
or disease that w ould affect their ham string flexibility, or circulation problem s. Subjects w ere also screened to ensure that they were recreationally active as defined by engaging in physical activity 1 to 5 h/w k.17 Subjects were also screened to determ ine if they had lim itations in ham string flexibility before the study. Lim itation in ham string flexibility was defined by having hip-flexion ROM less than 90° as m easured by a passive straight-leg-raise test. All subjects provided w ritten inform ed consent, and the study was approved by the institutional review board.
Study Analysis A 2 x 4 x 6 factorial with repeated m easures on all factors guided data collection. The independent variables were tim e (pretreatm ent and posttreatm ent), treatm ent (static stretching only [SS], foam rolling only [FM], foam rolling and static stretching [FR/SS], and control), and day (1, 2, 3, 4, 5, and 6). The dependent variable was change in passive hip-flexion ROM from the pretreatm ent m easure on day 1 to the posttreatm ent m easure on day 6.
Instruments We m easured passive hip-flexion ROM w ith a Baseline bubble inclinom eter (Fabrication Enterprises, Inc, W hite Plains, NY). Each m easure was taken from the subject’s dom inant leg (ie, the leg with w hich he or she kick a ball) w hile he or she lay on a padded table in a supine posi tion. The use o f bubble inclinom eters is reported to have an intrarater reliability that ranges from .92 to .97.1819 For each hip-flexion ROM m easure, we used two 8-cm-wide x 213-cm-long belts with the slack removed to minimize any accessory movement of the pelvis and non dominant leg. All foam-rolling procedures were completed with a 15-cm x 91-cm Cando EVA foam roller (Chatta nooga Group, Chattanooga, TN). During all foam rolling we used a digital metronome (Evets Corp, Camarillo, CA) set at 60 beats/min to maintain a consistent speed.
297
consistency of each measure, the center point between the A SIS and the superior pole o f the patella on the subject’s dom inant leg was marked with a pen. We then placed 1 end o f the inclinom eter on the mark and passively flexed the subject’s hip to the point o f discom fort to establish the baseline ROM m easure (Figure 1). Subjects receiving SS rem ained in a supine position on the padded table, where 3 consecutive passive stretches were perform ed w hile their nondom inant leg and ASIS rem ained secured to the table. For each stretch, the inves tigator moved the subject’s leg to the point o f discom fort w ithout pain. The stretch was then held for 1 m inute in duration with 30-second rests betw een stretches. Subjects assigned to receive the F R placed the foam roller betw een their ischial tuberosity and a hard surface (ie, floor) with their legs m aintained in an extended posi tion, keeping their ankles relaxed and oriented upward (Figures 2 and 3). Subjects were then instructed to support their body w eight with their arms extended but to allow as m uch pressure between the ham string m uscle group and the foam roller. Subjects then actively moved the foam roller at a cadence of 1 second inferior (ischial tuberosity to popliteal fossa) and 1 second superior (popliteal fossa to ischial tuberosity) as determ ined with the m etronom e. The foam-rolling protocol included three 1-minute repeti tions with a 30-second break between repetitions to allow subjects to rest their arm s. Subjects random ly assigned to the FR/SS group perform ed the same foam -rolling protocol as those in the FR group and w ere stretched in the same m anner as those in the SS group. Immediately after each treatment, passive hip-flexion ROM measures were repeated. Those in the control group received the same hip-flexion-ROM measures at the same tim e interval as those in the FR/SS group, w hich was approximately 5 minutes after the preintervention measure.
Statistical Analysis We calculated the average change and standard error in passive hip-flexion ROM. We then used the G LIM M IX
Testing Procedures Subjects reported to the laboratory on 6 days separated by at least 48 hours dressed in shorts and a T-shirt. On arrival, they were random ly assigned to 1 o f the 4 treat ment groups by selecting a num ber 1, 2, 3, or 4 from a container. Subjects assigned to receive FR and FR/SS were allowed to fam iliarize them selves with the foam roller. Fam iliarization consisted of giving the subjects specific instructions on how to perform foam rolling and a dem onstration by the first author to ensure correct technique. We did not allow subjects to practice on the foam roller, as this may have influenced the results. Subjects were then positioned supine on a padded table where their nondom inant leg and hips were secured with the straps. O ne belt was applied over the subject’s nondom inant thigh, ju st superior to the patella, and the other strap was applied over each anterosuperior iliac spine (ASIS; Figure 1). U sing the bubble inclinom eter, pretreatm ent hipflexion ROM m easures were then com pleted. To ensure
Figure 1 — Measurement procedures for hip-flexion range of motion. Care was taken to ensure that the contralateral leg and pelvis were secured to the table with individual straps.
298
Mohr, Long, and Goad
procedure for general linear mixed models20 to perform a 2-way ANCOVA (time x treatment), with change in ROM between the initial passive hip-flexion ROM mea sure on day I and the last (posttreatment) hip-flexion ROM measure on day 6 as the dependent variable. We used the pretreatment mean between treatment groups as the covariate. Independent t tests were then used to isolate individual differences. Results were considered statistically significant at an alpha level of P < .05.
Confidence intervals (95%) were calculated for passive hip-flexion range of motion. Between-groups effect sizes were calculated against the control using Cohen d.2[ We used the Statistical Analysis System (SAS, Cary, NC) to analyze all data.
Results Descriptive statistics (mean ± SE) for the change in pas sive hip flexion, 95% confidence intervals, and effect sizes are summarized in Table 1. There was a significant change in passive hip-flexion ROM regardless of treatment (F317 = 8.06, P =.001). Subjects receiving FR/SS had a greater change in passive hip-flexion ROM compared with the SS (rl7 = -2.07, P = .04), FR (r ,g = 3.11, P = .006), and control (f13 = 5.00, P= .001). There were no significant differences between any of the other treatments (P>.09).
Discussion
Figure 2 — Starting-position foam roller at the ischial tuber
osity.
Figure 3 — Ending-position foam roller at the inferior portion of the popliteal fossa.
Our objective was to determine if foam rolling performed before static stretching would influence passive hipflexion ROM. We hypothesized that since static stretching has been reported to improve hip-flexion ROM, 1-4 6-1017 the addition of foam rolling with its claimed benefits of improving flexibility15 would increase passive hip-flexion ROM more than static stretching or foam rolling alone. Oftentimes clinicians incorporate a therapeutic intervention before warm-up activities. 15 We decided to use the foam roller before a static-stretching protocol to act as a warm-up for the hamstring muscle group. With a greater change in passive hip-flexion ROM observed in those receiving FR/SS, it appears that the combination of the foam roller before the static stretching resulted in therapeutic benefits similar to those reported by others who have examined therapeutic interventions prior to static stretching.3-4 The greater change in passive hip-flexion ROM observed in the FR/SS group as compared with the SS, FR, and control groups is likely due to increases in temperature. Although it was not possible to measure surface or intramuscular temperature during the foam rolling procedure, it is likely that the constant movement before static stretching increased intramuscular tissue temperature and blood flow, both of which are reported to increase the viscoelastic properties of muscle.22 Another possible explanation is the thixotropic property reported
Table 1 Average Change in Passive Hip-Flexion Range of Motion From the Pretreatment Measure, 95% Confidence Intervals, and Calculated Effect Size Tim e
Change from baseline Confidence interval Between-groups effect size
Static stretch only
Foam roller + static stretch3
Foam roller only
Control
12.26 ±4.21 (2.62,21.83) 2.63
23.55 ± 3.53 (15.57,31.53) 7.06
6.88 ± 3.97 (-2.07, 15.84) 1.81
3.74 ± 1.81 (-.037, 7.85) —
Note: These average changes were based on the unequal variance between pretreatment ranges of motion (n = I0 subjects/treatment; mean ± SE). a Foam roller + static stretch > static stretch only, foam roller only, and control, postintervention; P < .05.2
Stretching
in muscle and fascia.23 It is suggested that changes in the thixotropic properties of muscle and fascia decrease tissue viscosity. As a result, tissue becomes less resistant when a stretch is applied, resulting in greater hip-flexion ROM. Few investigators have studied the use of a foamroller treatment. In 1 study it was reported that ROM measures did not change after a foam-rolling treatment when subjects in the control group also presented with increased ROM.16 Although our subject demographics and foam-rolling procedure (ie, three 1-min repetitions totaling 6 min) were similar, we secured subjects’ hip and pelvis to the table to prevent any accessory motion and we measured passive hip-flexion ROM instead of active knee-extension ROM. By securing the subjects’ hip and nondominant leg with straps with a different method of measuring ROM, it appears that more application times or how the measures are taken influenced hip-flexion ROM. The results of this study can only be limited to indi viduals who have less than 90° of passive hip-flexion ROM in their dominant leg. Future studies involving a foam roller applied to both hamstring muscle groups before or after a static-stretching protocol may present different results. Clinically, the results of this study can be used to support the use of a foam roller in combination with a 2-week static-stretching protocol. Our results showed an increase in hip-flexion ROM across all treatment groups, with the greatest gains in the foam-rolling and static stretching group. Clinicians therefore should incorporate a foam-rolling protocol of the hamstrings before static stretching in uninjured subjects who have less than 90° of hamstring flexibility.
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