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Geriatr Gerontol Int 2014
ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH
Muscle function in aged women in response to a water-based exercises program and progressive resistance training Paulo Cesar Barauce Bento and André Luiz Felix Rodacki Department of Physical Education, Federal University of Paraná, Curitiba, Brazil
Aim: The purpose of the present study was to determine the effects of a water-based exercise program on muscle function compared with regular high-intensity resistance training. Methods: Older women (n = 87) were recruited from the local community. The inclusion criteria were, to be aged 60 years or older, able to walk and able to carry out daily living activities independently. Participants were randomly assigned to one of the following groups: water-based exercises (WBG), resistance training (RTG) or control (CG). The experimental groups carried out 12 weeks of an excise program performed on water or on land. The dynamic strength, the isometric peak, and rate of torque development for the lower limbs were assessed before and after interventions. Results: The water-based program provided a similar improvement in dynamic strength in comparison with resistance training. The isometric peak torque increased around the hip and ankle joints in the water-based group, and around the knee joint in the resistance-training group (P < 0.05). The rate of torque development increased only in the water-based group around the hip extensors muscles (P < 0.05). Conclusions: Water-based programs constitute an attractive alternative to promote relevant strength gains using moderate loads and fast speed movements, which were also effective to improve the capacity to generate fast torques. Geriatr Gerontol Int 2014; ••: ••–•• Keywords: muscular function, resistance training, water-based exercise.
Introduction Aging is accompanied by a number of changes in the neuromuscular system that can compromise muscle function, which occur because of a reduction in the number and size of the fibers, especially the fast twitch fibers (type II).1 Neural factors, such as co-activation of the antagonist muscle, a diminished motor unit recruitment and discharge rate, also play a role in the ability of a muscle to produce and sustain force.2 These changes result in diminished muscle strength,3,4 power5 and resistance to fatigue6 that impact on functionality and the loss of independency.2 Several studies have shown that resistance training has positive effects on muscle function in the elderly,
Accepted for publication 16 September 2014. Correspondence: Dr André Luiz Felix Rodacki PhD, Department of Physical Education, Federal University of Paraná, R. Coração de Maria, 92, Jardim Botânico, Curitiba 82250, Paraná, Brazil. Email: [email protected]
© 2014 Japan Geriatrics Society
which increases after high intensity7 or moderate intensity resistance training.8 Despite such positive effects, older adults might not enjoy or even might not be able to carry out high-intensity resistance exercises. Thus, other exercise protocols might be preferred. Water-based exercises are often indicated to older adults because of the physical properties (e.g. buoyancy and viscosity). The immersion provides a joint load reduction and high resistance to move the body through the water,9 which might constitute an interesting approach to improving muscle strength.9,10 There are a few studies that compared the effects of water- and land-based exercise programs on muscle strength, but the results cannot be applied to the elderly as they analyzed young women.10,11 Taunton compared the effects of a moderate water- and land-based exercise program in a group of elderly women, which showed improvements in aerobic capacity, but no changes in muscle strength, irrespective of the exercise program.12 In contrast, others have found increased peak torque in the lower limbs after a water-based exercise carried out with devices to increase movement resistance combined doi: 10.1111/ggi.12418
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PCB Bento and ALF Rodacki
with high-speed movements.13,14 Bento et al. also found an increased rate of torque development, which could have emerged from the type of stimulus applied in the water-based program.14 The comparison between a water-based exercise program using resistance devices and executing high-speed movements and resistance training using high intensity (high loads) might provide a better understanding about the effect of these exercise programs on muscle function in the elderly. Therefore, the present study aimed to analyze the effects of a water-based program on dynamic strength, peak and rate of torque development during a maximal voluntary isometric contraction, and to compare these effects with a regular high-intensity resistance-training program.
Methods Participants A total of 87 older adults living in the community near the Federal University of Parana, Curitiba, Brazil, volunteered to participate. They were contacted using local media and flyers, and received details about the aims and procedures involved in the study. The inclusion criteria were: aged 60 years or older, able to walk and able to carry out the activities of daily living independently. Volunteers engaged to other systematic physical activity programs during the 6 months that preceded the study were not included. A physician screened the volunteers for health problems (e.g. heart conditions, general health problems) and restrictions to exercise in the water (e.g. skin problems, etc.). Participants answered a questionnaire designed to determine their level of physical activities, and were classified as: very active (56%), active (21,8%), insufficiently active (15,6%) and sedentary (6%).15 After that they were randomly assigned, according to the level of physical activities, to a water-based group (WBG; n = 25; age 65.5 years; 74.5 kg; 157 cm), a resistancetraining group (RTG; n = 23; age 67.3 years; 73.2 kg; 158.3 cm) or a control group (CG; n = 19; age 66.2 years; 73.1 kg; 153.3 cm). This approach was designed to avoid bias effects and to form homogeneous groups based on physical activity level. Procedures were approved by the University’s ethics committee. Figure 1 represents the experimental design of the study.
Dynamic strength measurements Two familiarization sessions were carried out to determine the dynamic strength of the lower limb using the one maximal repetition test (1RM) on the following weight equipment: leg-press, knee extensor and flexor (Nakagym, Sao Paulo, Brazil) because of the importance of the muscle of the lower limbs to carry out the activi2
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ties of daily living, such as up and down stairs, and stand up from a chair.16 After 10 min of warm-up, the participants carried out up to five trials to determine the maximal load. The exercises were carried out in a random order, and verbal encouragement was provided during the tests. There were two testing sessions, with a 2–5-min rest period between trials and a 48-h rest period between sessions.
Maximal voluntary isometric contraction The torque of the hip, knee, and ankle flexor and extensor muscles was assessed after two familiarization sessions. Volunteers were positioned in a recumbent posture where proximal segments were firmly secured and stabilized by a Velcro strap while the tested segments were positioned at approximately 90°.7 The tests were carried out in a random order. The time–force curve traces were determined with a load cell (Model CZC500, Kratos, São Paulo, Brazil) firmly and perpendicularly attached to an adjustable pole to the dominant tested segment. The perpendicular distance between the load cell and the joint center was determined, and used to calculate the net joint torques. Figure 2 presents a schematic representation of the postures used in the maximal voluntary isometric contraction tests. Participants were instructed to produce torque as fast and hard as possible, and to sustain the contraction for approximately 2–3 s. The greatest peak torque obtained in three maximal trials was used for further analysis. Each maximal trial was followed by a 2-min rest. The force– time signals was a sample with a frequency of 1 kHz, amplified (model IK-1C; Kratos, São Paulo, Brazil), converted to digital signals with the aid of a 16-bit A/D card (model NI USB6218; National Instruments, Austin, TX, USA) and filtered with a second order recursive filter (20 Hz). Peak torque was determined as the highest value obtained after the onset of the voluntary contraction. The rate of torque development was defined as the slope of the force–time curve from 20% to 80% of the peak values.17 The coefficient of determination was calculated to assess the fit of the regression equations (R2 = 0.98). A customized routine was used to calculate both variables (Matlab 7.0, Natick, MA, USA).
Intervention programs Both exercise programs were carried out for 12 weeks, three times per week (60 min/session). The water-based exercise was carried out in an indoor swimming pool with the water level set at approximately the xyphoid process height, and the temperature ranged between 28 and 30°C. All sessions included a 10-min warm-up, 20 min of aerobic exercises and 20 min of exercises designed to strengthening the lower limb muscles using © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Assessed for eligibility (n=87)
Balanced and randomized
Control group (n=19)
Lost follow-up (n=03)
Figure 1 Schematic representation of participant recruitment and allocation.
Analyzed (n=16)
resistance devices, and with movements carried out at high speed. Stretching exercises were included in the last 10 min of the sessions. Aerobic activities included the following exercises: long-lever pendulum-like movements of the lower extremities; forward and backward jogging with arms pushing, pulling and pressing; and leaps, kicks, leg crossovers and hopping movements focusing on traveling in multiple directions. Exercise intensity was controlled using the rate of a perceived exertion (RPE; 12–16 on the 15-point Borg scale) and heart rate (progressing from 40% to 60% of the heart rate reserve), according to the American College of Sports Medicine recommendation.18 In the final 4 weeks, exercises were executed without the feet contacting the bottom of the pool in an attempt to increase exercise intensity. The strengthening exercises were: knee and hip extension– flexion, and adduction–abduction with extended knee, double knee lifts and side press kicks while holding onto the pool edge.13 Three sets of each exercise were carried out for 40 s with a rest interval of 20 s at a moderate © 2014 Japan Geriatrics Society
Rsistance training group (n=23)
Discontinued intervention (n=07)
Analyzed (n=16)
Excluded (n=11) Refused to participate (n=9)
Water-based training group (n=25)
Discontinued intervention (n=05)
Analyzed (n=20)
speed, at a RPE of 12 during the first 4 weeks. For weeks 5–8, intensity was increased by augmenting movement speed and by including water-resistive devices (RPE or 12–14). Finally, during the last 4 weeks, exercises were carried out with the highest voluntary speed (RPE 14–16). The resistance-training program included specific exercises to strengthen the hip, knee, and ankle flexion and extension, hip adductor and abductor muscles, and complementary exercises to the trunk and upper limbs. Two to three sets of each exercise were carried out with eight to 12 maximal repetition load and a 2-min rest.18 Each session included a 10-min warm-up followed by 40 min of specific exercises to strengthen the lower limb muscle and complementary exercises. A period of 10 min of stretching was applied at the end of the sessions. Two sets of eight to 12 maximal repetitions were carried out during the first 4 weeks. For weeks 5–8, two to three sets of eight maximal repetitions were carried out, and in the last 4 weeks, three sets of eight maximal repetitions were executed. There was a 2-min rest |
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Dorsiflexors
Hip flexors
Knee flexors
Plantarflexors
Hip extensors
Knee extensors
interval between exercises during the whole training program. The compliance rate was 94% and 85% for water-based and resistance-training exercise programs, respectively.
Figure 2 Schematic representation of the postures used in the Maximal Isometric Voluntary Contraction Test. 1RM, one maximal repetition test; CG, control group; RTG, resistance training group; WBG, water-based group.
tistical analysis were carried out using Statistica Software (version 7; StatSoft, Tulsa, OK, USA), and the significance level was set at P < 0.05.
Results Data analysis The Shapiro–Wilk test confirmed normality of most variables. Variables without normal distribution were transformed by logarithmic procedures. The knee flexors peak torque and rate of torque development were analyzed using a non-parametric test, because it was not possible to normalize the data after transforming procedures. A two-way repeated-measure analysis of variance (ANOVA) was applied to determine if training (independent variable) was effective in changing the dynamic strength, peak and rate of torque development of the lower limb (dependent variables). Time was considered as a repeated factor (pre- and post-assessments). An initial analysis using a one-way ANOVA showed between-groups differences in the initial values. Then, pretest values were used as covariate to compare posttest effects. Tukey’s post-hoc test was used for multiple comparisons in case of significant differences. All sta4
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No differences were found between groups for physical characteristics and age (P > 0.05). Dynamic strength, peak and rate of torque development were also similar at baseline (P > 0.05). Figure 3 presents values for dynamic strength to the knee extension (Fig. 3a), knee flexion (Fig. 3b) and leg-press (Fig. 3c), in the pre- and post-test assessments for the WBG, RTG and CG. Dynamic strength improvement for the knee extensor (11.6% and 35.6%), and flexor muscles (13.2% and 21.2%) in the WBG and RTG, respectively (P < 0.05). Performance in the leg-press also increased in both groups (16.9% and 27.4%). No differences were found between groups in the post-test in the dynamic tests (P > 0.05).
Maximum voluntary isometric peak torque The WBG increased 42% in the maximum voluntary isometric contraction (MVIC) of the hip extensors and © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Rate of torque development The rate of torque development (RTD) around the hip, knee and ankle joints are shown in Figure 5. The RTD of the WBG increased only around the hip extensors muscles (53%) after training (P > 0.05). No further differences were observed for the experimental and control groups in any of the other tested joints (P > 0.05).
Discussion
Figure 3 Dynamic strength (one maximal repetition test) of the (a) knee extension, (b) knee flexion and (c) leg-press exercise of the water-based group (WBG), resistance-training group (RTG) and control group pre- and post-training (mean ± standard deviation). *Post-test values greater than pretest values (P < 0.05).
50% of the plantar flexors muscles (P < 0.05), but the peak torque remained unchanged in the other muscle groups in the after training. The RTG showed 26% improvement to the peak torque of knee flexors muscles (P < 0.05), without alterations to the other muscles groups in the post-test (P > 0.05). The WBG showed the largest gains for the hip extensor (P < 0.05) and ankle plantar flexor (P < 0.05) muscles in comparison with the CG, showing an important effect of the water-based training stimulus. The MVIC results are presented in Figure 4. © 2014 Japan Geriatrics Society
The main finding of the present study was that 12 weeks of a moderate-intensity water-based program provided a similar improvement in the dynamic strength (1RM) in comparison with resistance training. The peak torque increased around the hip and ankle joints in the waterbased group, and around the knee joint in the resistance-training group. The RTD increased only in the water-based group around the hip extensors muscles. Strength gains in response to resistance training are variable across the studies, as a result of multiple factors that include: population, intensity, program duration and the initial strength levels of the participants.19 The dynamic strength improvement varied from 21% for the knee flexor muscles to 35.6% for the leg-press exercise, which are slightly smaller than that reported by other studies.7,8 Strength differences at baseline might explain the larger improvements observed in other studies.19,20 The MVIC around the knee gains in the resistance training group was not observed in other muscles. Hortobagyi et al. also failed to find changes in the MVIC, despite of the dynamic strength improvements.21 The dynamic nature of the training program (dynamic contractions) might have provided a more specific stimulus, which cannot be fully detected in static tests (i.e. by isometric tests). The rate of torque development did not change after training in the resistance-training group. The low muscle contraction velocity applied to move high resistances might explain such results. In contrast, it might have constituted a specific stimulus for improving the RTD, which requires moderate loads and fast contractions.22 The result of the present study does not support the findings of Petric et al., who compared strength gains between water-based and resistance-training programs in elderly women, and did not find improvements after training, irrespective of the program type.12 Perhaps, the lack of specificity of the tests (i.e. handgrip strength) used in that study could explain the similarities between groups, especially because most changes are likely to occur in the lower limbs. Others studies compared the effects of water- versus land-based exercises on dynamic strength; however, the participants were middleaged10,23 or suffering from health conditions, such as fibromyalgia24 or osteoarthritis,25 and were generally |
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PCB Bento and ALF Rodacki
Figure 4 Maximum voluntary isometric contraction (MVIC) of the (a) hip extension and flexion, (b) knee extension and flexion, and (c) plantar flexion and dorsi flexion of the water-based group (WBG), resistance training group (RTG) and control group (CG) pre- and post-training (mean + standard deviation). *Post-test values greater than pretest values (P < 0.05).
weaker than others with a regular health status. Thus, comparison must be viewed with caution, especially because weaker subjects tend to present larger muscle function gains.10 Two studies determined the dynamic strength of the lower limbs after water-based exercises.13,26 Takeshima et al., found strength increments for the knee extensor (8%) and flexor muscles (13%) after 12 weeks of training, which are similar to the gains detected in the present study (11.6% and 13.2%, respectively).26 Tsourlou et al. applied a training program that was very similar to ours, but observed higher increments.13 The longer duration of the training period (24 weeks) and the lack of a familiarization period could account for such discrepancies. It is well known that discarding a period of habituation might enhance performance gains and obscure comparisons.27 The MIVC increase observed in the hip extensors muscles for the water-based group (42%) was larger 6
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than that (27%) observed by Wang et al.25 The constant increases in the intensity of the exercise program (each 4 weeks) and the increased speed of movements imposed during the water-based sessions could have provided an adequate stimulus to improve muscle strength. Furthermore, the buoyancy force is an additional resistive stimulus when movements are carried out in the direction to the bottom of the swimming pool, which might at least partially explain the gains observed around the hip extensor muscles. In contrast, movements carried out upward are assisted by buoyancy force, and could clarify the lack of MIVC improvement around the hip flexor muscles.9 The MIVC of the knee extensor and flexor muscles did not change after training, and indicated that not all muscle groups respond in the same way to the exercises in the water. Indeed, the area of the more distal segments of the lower limbs is relatively small, and might not be sufficient to generate drag forces large enough to elicit resistive forces to © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Figure 5 Rate of torque development (RTD) of the (a) hip extension and flexion, (b) knee extension and flexion, and (c) plantar flexion and dorsi flexion of the water-based group (WBG), resistance training group (RTG) and control group (CG) pre- and post-training (mean + standard deviation). *Post-test values greater than pretest values (P < 0.05).
promote large strength gains, despite the use of resistance devices. The MIVC increases in the plantar-flexors muscles (50%) might be explained by the large amount of stimulus required by the displacements imposed during the water-based sessions. Furthermore, the role of the plantar-flexors muscles to maintain and recover perturbed balance as a result of the water turbulence could have been an important additional stimulus. Not surprisingly, no changes were observed around the dorsi-flexor muscles, which are far less used while walking in shallow water.28 The water-based program was effective for improving the dynamic strength of the lower limb to the same extent as that obtained from the resistance-training program. In addition, water-based programs were more suitable for promoting strength and the rate of torque development around the hip and ankle than resistance training. Thus, water-based programs constitute an attractive alternative for promoting relevant gains using moderate loads and fast speed movements, which are © 2014 Japan Geriatrics Society
also effective for improving the capacity to generate fast torques. Generating fast torques might be of decisive importance while recovering from a slip or trip, and could prevent an accidental fall.
Disclosure statement We declare that the present study did not receive any financial support or relationship that may pose potential conflicts of interest. No potential conflicts of interest were disclosed.
References 1 Narici MV, Maganaris CN, Reeves ND, Capodaglio P. Effect of aging on human muscle architecture. J Appl Physiol 2003; 95: 2229–2234. 2 Clark BC, Manini TM. Functional consequences of sarcopenia and dynapenia in the elderly. Curr Opin Clin Nutr Metab Care 2010; 13: 271–276.
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PCB Bento and ALF Rodacki 3 Frontera WR, Hughes VA, Fielding RA, Fiatarone MA, Evans WJ, Roubenoff R. Aging of skeletal muscle: a 12-yr longitudinal study. J Appl Physiol 2000; 88 (4): 1321– 1326. 4 Delmonico MJ, Harris TB, Visser M et al. Longitudinal study of muscle strength, quality, and adipose tissue. Am J Clin Nutr 2009; 90: 1579–1585. 5 Candow DG, Chilibeck PD. Differences in size, strength, and power of upper and lower body muscle groups in young and older men. J Gerontol A Biol Sci Med Sci 2005; 60: 148–156. 6 Petrella JK, Kim J, Tuggle SC, Hall SR, Bamman MM. Age differences in knee extension power, contractile velocity, and fatigability. J Appl Physiol 2005; 98: 211–220. 7 Persch LN, Ugrinowitsch C, Pereira G, Rodacki ALF. Strength training improves fall-related gait kinematics in the elderly: a randomized controlled trial. Clin Biomech 2009; 24 (10): 819–825. 8 Kalapotharakos VI, Michalopoulos M, Tokmakidis SP, Godolias G, Gourgoulis V. Effects of a heavy and a moderate resistance training on functional performance in older adults. J Strength Cond Res 2005; 19 (3): 652–657. 9 Becker BE. Aquatic therapy: scientific foundations and clinical rehabilitation applications. PM R 2009; 1 (9): 859– 872. 10 Pöyhönen T, Kyröläinen H, Keskinen KL, Hautala A, Savolainen J, Mälkiä E. Electromyographic and kinematic analysis of therapeutic knee exercises under water. Clin Biomech 2001; 16: 496–504. 11 Petrick M, Paulsen T, George J. Comparison between quadriceps muscle strengthening on land and in water. Physiotherapy 2001; 87: 310–317. 12 Taunton JE, Rhodes EC, Wolski LA et al. Effect of landbased and water-based fitness programs on the cardiovascular fitness, strength and flexibility of women aged 65–75 years. Gerontology 1996; 42: 204–210. 13 Tsourlou T, Benik A, Dipla K, Zafeiridis A, Kellis S. The effects of a twenty-four-week aquatic training program on muscular strength performance in healthy elderly women. J Strength Cond Res 2006; 20 (4): 811–818. 14 Bento PCB, Pereira G, Ugrinowitsch C, Rodacki ALF. The effects of a water-based exercise program on strength and functionality of older adults. J Aging Phys Act 2012; 20: 469–483. 15 Mazo GZ, Virgilio M, De Barros G. Aplicação do Questionário Internacional de Atividades Físicas para avaliação do nível de atividades físicas de mulheres idosas?:
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validade concorrente e reprodutibilidade teste-reteste. R Bras Ci e Mov 2004; 12: 25–34. Hortobágyi T, Mizelle C, Beam S, DeVita P. Old adults perform activities of daily living near their maximal capabilities. J Gerontol A Biol Sci Med Sci 2003; 58 (5): M453– M460. Bento PCB, Pereira G, Ugrinowitsch C, Rodacki ALF. Peak torque and rate of torque development in elderly with and without fall history. Clin Biomech 2010; 25: 450–454. Nelson ME, Rejeski WJ, Blair SN et al. Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Circulation 2007; 116: 1094–1105. Frontera WR, Meredith CN, O’Reilly KP, Knuttgen HG, Evans WJ. Strength conditioning in older men: skeletal muscle hypertrophy and improved function. J Appl Physiol 1988; 64: 1038–1044. Lexell J. Strength training and muscle hypertrophy in older men and women. Top Geriatr Rehabil 2000; 15: 41–46. Hortobágyi T, Tunnel D, Moody J, Beam S, DeVita P. Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults. J Gerontol A Biol Sci Med Sci 2001; 56: B38–B47. Barry BK, Carson RG. The consequences of resistance training for movement control in older adults. J Gerontol A Biol Sci Med Sci 2004; 59: 730–754. Ambrosini AB, Brentano MA, Coertjens M, Fernando L, Kruel M. The effects of strength training in hydrogymnastics for middle-age women. IJARE 2010; 4: 153–162. Gusi N, Tomas-Carus P, Häkkinen A, Häkkinen K, Ortega-Alonso A. Exercise in waist-high warm water decreases pain and improves health-related quality of life and strength in the lower extremities in women with fibromyalgia. Arthritis Rheum 2006; 55: 66–73. Wang T-J, Belza B, Elaine Thompson F, Whitney JD, Bennett K. Effects of aquatic exercise on flexibility, strength and aerobic fitness in adults with osteoarthritis of the hip or knee. J Adv Nurs 2007; 2: 141–152. Takeshima N, Rogers ME, Watanabe E et al. Water-based exercise improves health-related aspects of fitness in older women. Med Sci Sports Exerc 2002; 34: 544–551. Ploutz-Snyder LL, Giams E. Orientation and familiarization to 1RM strength testing in old and young women. J Strength Cond Res 2001; 15: 19–23. Barela AMF, Stolf SF, Duarte M. Biomechanical characteristics of adults walking in shallow water and on land. J Electromyogr Kinesiol 2006; 16 (3): 250–256.
© 2014 Japan Geriatrics Society
Geriatr Gerontol Int 2014
ORIGINAL ARTICLE: EPIDEMIOLOGY, CLINICAL PRACTICE AND HEALTH
Muscle function in aged women in response to a water-based exercises program and progressive resistance training Paulo Cesar Barauce Bento and André Luiz Felix Rodacki Department of Physical Education, Federal University of Paraná, Curitiba, Brazil
Aim: The purpose of the present study was to determine the effects of a water-based exercise program on muscle function compared with regular high-intensity resistance training. Methods: Older women (n = 87) were recruited from the local community. The inclusion criteria were, to be aged 60 years or older, able to walk and able to carry out daily living activities independently. Participants were randomly assigned to one of the following groups: water-based exercises (WBG), resistance training (RTG) or control (CG). The experimental groups carried out 12 weeks of an excise program performed on water or on land. The dynamic strength, the isometric peak, and rate of torque development for the lower limbs were assessed before and after interventions. Results: The water-based program provided a similar improvement in dynamic strength in comparison with resistance training. The isometric peak torque increased around the hip and ankle joints in the water-based group, and around the knee joint in the resistance-training group (P < 0.05). The rate of torque development increased only in the water-based group around the hip extensors muscles (P < 0.05). Conclusions: Water-based programs constitute an attractive alternative to promote relevant strength gains using moderate loads and fast speed movements, which were also effective to improve the capacity to generate fast torques. Geriatr Gerontol Int 2014; ••: ••–•• Keywords: muscular function, resistance training, water-based exercise.
Introduction Aging is accompanied by a number of changes in the neuromuscular system that can compromise muscle function, which occur because of a reduction in the number and size of the fibers, especially the fast twitch fibers (type II).1 Neural factors, such as co-activation of the antagonist muscle, a diminished motor unit recruitment and discharge rate, also play a role in the ability of a muscle to produce and sustain force.2 These changes result in diminished muscle strength,3,4 power5 and resistance to fatigue6 that impact on functionality and the loss of independency.2 Several studies have shown that resistance training has positive effects on muscle function in the elderly,
Accepted for publication 16 September 2014. Correspondence: Dr André Luiz Felix Rodacki PhD, Department of Physical Education, Federal University of Paraná, R. Coração de Maria, 92, Jardim Botânico, Curitiba 82250, Paraná, Brazil. Email: [email protected]
© 2014 Japan Geriatrics Society
which increases after high intensity7 or moderate intensity resistance training.8 Despite such positive effects, older adults might not enjoy or even might not be able to carry out high-intensity resistance exercises. Thus, other exercise protocols might be preferred. Water-based exercises are often indicated to older adults because of the physical properties (e.g. buoyancy and viscosity). The immersion provides a joint load reduction and high resistance to move the body through the water,9 which might constitute an interesting approach to improving muscle strength.9,10 There are a few studies that compared the effects of water- and land-based exercise programs on muscle strength, but the results cannot be applied to the elderly as they analyzed young women.10,11 Taunton compared the effects of a moderate water- and land-based exercise program in a group of elderly women, which showed improvements in aerobic capacity, but no changes in muscle strength, irrespective of the exercise program.12 In contrast, others have found increased peak torque in the lower limbs after a water-based exercise carried out with devices to increase movement resistance combined doi: 10.1111/ggi.12418
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PCB Bento and ALF Rodacki
with high-speed movements.13,14 Bento et al. also found an increased rate of torque development, which could have emerged from the type of stimulus applied in the water-based program.14 The comparison between a water-based exercise program using resistance devices and executing high-speed movements and resistance training using high intensity (high loads) might provide a better understanding about the effect of these exercise programs on muscle function in the elderly. Therefore, the present study aimed to analyze the effects of a water-based program on dynamic strength, peak and rate of torque development during a maximal voluntary isometric contraction, and to compare these effects with a regular high-intensity resistance-training program.
Methods Participants A total of 87 older adults living in the community near the Federal University of Parana, Curitiba, Brazil, volunteered to participate. They were contacted using local media and flyers, and received details about the aims and procedures involved in the study. The inclusion criteria were: aged 60 years or older, able to walk and able to carry out the activities of daily living independently. Volunteers engaged to other systematic physical activity programs during the 6 months that preceded the study were not included. A physician screened the volunteers for health problems (e.g. heart conditions, general health problems) and restrictions to exercise in the water (e.g. skin problems, etc.). Participants answered a questionnaire designed to determine their level of physical activities, and were classified as: very active (56%), active (21,8%), insufficiently active (15,6%) and sedentary (6%).15 After that they were randomly assigned, according to the level of physical activities, to a water-based group (WBG; n = 25; age 65.5 years; 74.5 kg; 157 cm), a resistancetraining group (RTG; n = 23; age 67.3 years; 73.2 kg; 158.3 cm) or a control group (CG; n = 19; age 66.2 years; 73.1 kg; 153.3 cm). This approach was designed to avoid bias effects and to form homogeneous groups based on physical activity level. Procedures were approved by the University’s ethics committee. Figure 1 represents the experimental design of the study.
Dynamic strength measurements Two familiarization sessions were carried out to determine the dynamic strength of the lower limb using the one maximal repetition test (1RM) on the following weight equipment: leg-press, knee extensor and flexor (Nakagym, Sao Paulo, Brazil) because of the importance of the muscle of the lower limbs to carry out the activi2
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ties of daily living, such as up and down stairs, and stand up from a chair.16 After 10 min of warm-up, the participants carried out up to five trials to determine the maximal load. The exercises were carried out in a random order, and verbal encouragement was provided during the tests. There were two testing sessions, with a 2–5-min rest period between trials and a 48-h rest period between sessions.
Maximal voluntary isometric contraction The torque of the hip, knee, and ankle flexor and extensor muscles was assessed after two familiarization sessions. Volunteers were positioned in a recumbent posture where proximal segments were firmly secured and stabilized by a Velcro strap while the tested segments were positioned at approximately 90°.7 The tests were carried out in a random order. The time–force curve traces were determined with a load cell (Model CZC500, Kratos, São Paulo, Brazil) firmly and perpendicularly attached to an adjustable pole to the dominant tested segment. The perpendicular distance between the load cell and the joint center was determined, and used to calculate the net joint torques. Figure 2 presents a schematic representation of the postures used in the maximal voluntary isometric contraction tests. Participants were instructed to produce torque as fast and hard as possible, and to sustain the contraction for approximately 2–3 s. The greatest peak torque obtained in three maximal trials was used for further analysis. Each maximal trial was followed by a 2-min rest. The force– time signals was a sample with a frequency of 1 kHz, amplified (model IK-1C; Kratos, São Paulo, Brazil), converted to digital signals with the aid of a 16-bit A/D card (model NI USB6218; National Instruments, Austin, TX, USA) and filtered with a second order recursive filter (20 Hz). Peak torque was determined as the highest value obtained after the onset of the voluntary contraction. The rate of torque development was defined as the slope of the force–time curve from 20% to 80% of the peak values.17 The coefficient of determination was calculated to assess the fit of the regression equations (R2 = 0.98). A customized routine was used to calculate both variables (Matlab 7.0, Natick, MA, USA).
Intervention programs Both exercise programs were carried out for 12 weeks, three times per week (60 min/session). The water-based exercise was carried out in an indoor swimming pool with the water level set at approximately the xyphoid process height, and the temperature ranged between 28 and 30°C. All sessions included a 10-min warm-up, 20 min of aerobic exercises and 20 min of exercises designed to strengthening the lower limb muscles using © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Assessed for eligibility (n=87)
Balanced and randomized
Control group (n=19)
Lost follow-up (n=03)
Figure 1 Schematic representation of participant recruitment and allocation.
Analyzed (n=16)
resistance devices, and with movements carried out at high speed. Stretching exercises were included in the last 10 min of the sessions. Aerobic activities included the following exercises: long-lever pendulum-like movements of the lower extremities; forward and backward jogging with arms pushing, pulling and pressing; and leaps, kicks, leg crossovers and hopping movements focusing on traveling in multiple directions. Exercise intensity was controlled using the rate of a perceived exertion (RPE; 12–16 on the 15-point Borg scale) and heart rate (progressing from 40% to 60% of the heart rate reserve), according to the American College of Sports Medicine recommendation.18 In the final 4 weeks, exercises were executed without the feet contacting the bottom of the pool in an attempt to increase exercise intensity. The strengthening exercises were: knee and hip extension– flexion, and adduction–abduction with extended knee, double knee lifts and side press kicks while holding onto the pool edge.13 Three sets of each exercise were carried out for 40 s with a rest interval of 20 s at a moderate © 2014 Japan Geriatrics Society
Rsistance training group (n=23)
Discontinued intervention (n=07)
Analyzed (n=16)
Excluded (n=11) Refused to participate (n=9)
Water-based training group (n=25)
Discontinued intervention (n=05)
Analyzed (n=20)
speed, at a RPE of 12 during the first 4 weeks. For weeks 5–8, intensity was increased by augmenting movement speed and by including water-resistive devices (RPE or 12–14). Finally, during the last 4 weeks, exercises were carried out with the highest voluntary speed (RPE 14–16). The resistance-training program included specific exercises to strengthen the hip, knee, and ankle flexion and extension, hip adductor and abductor muscles, and complementary exercises to the trunk and upper limbs. Two to three sets of each exercise were carried out with eight to 12 maximal repetition load and a 2-min rest.18 Each session included a 10-min warm-up followed by 40 min of specific exercises to strengthen the lower limb muscle and complementary exercises. A period of 10 min of stretching was applied at the end of the sessions. Two sets of eight to 12 maximal repetitions were carried out during the first 4 weeks. For weeks 5–8, two to three sets of eight maximal repetitions were carried out, and in the last 4 weeks, three sets of eight maximal repetitions were executed. There was a 2-min rest |
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Dorsiflexors
Hip flexors
Knee flexors
Plantarflexors
Hip extensors
Knee extensors
interval between exercises during the whole training program. The compliance rate was 94% and 85% for water-based and resistance-training exercise programs, respectively.
Figure 2 Schematic representation of the postures used in the Maximal Isometric Voluntary Contraction Test. 1RM, one maximal repetition test; CG, control group; RTG, resistance training group; WBG, water-based group.
tistical analysis were carried out using Statistica Software (version 7; StatSoft, Tulsa, OK, USA), and the significance level was set at P < 0.05.
Results Data analysis The Shapiro–Wilk test confirmed normality of most variables. Variables without normal distribution were transformed by logarithmic procedures. The knee flexors peak torque and rate of torque development were analyzed using a non-parametric test, because it was not possible to normalize the data after transforming procedures. A two-way repeated-measure analysis of variance (ANOVA) was applied to determine if training (independent variable) was effective in changing the dynamic strength, peak and rate of torque development of the lower limb (dependent variables). Time was considered as a repeated factor (pre- and post-assessments). An initial analysis using a one-way ANOVA showed between-groups differences in the initial values. Then, pretest values were used as covariate to compare posttest effects. Tukey’s post-hoc test was used for multiple comparisons in case of significant differences. All sta4
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No differences were found between groups for physical characteristics and age (P > 0.05). Dynamic strength, peak and rate of torque development were also similar at baseline (P > 0.05). Figure 3 presents values for dynamic strength to the knee extension (Fig. 3a), knee flexion (Fig. 3b) and leg-press (Fig. 3c), in the pre- and post-test assessments for the WBG, RTG and CG. Dynamic strength improvement for the knee extensor (11.6% and 35.6%), and flexor muscles (13.2% and 21.2%) in the WBG and RTG, respectively (P < 0.05). Performance in the leg-press also increased in both groups (16.9% and 27.4%). No differences were found between groups in the post-test in the dynamic tests (P > 0.05).
Maximum voluntary isometric peak torque The WBG increased 42% in the maximum voluntary isometric contraction (MVIC) of the hip extensors and © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Rate of torque development The rate of torque development (RTD) around the hip, knee and ankle joints are shown in Figure 5. The RTD of the WBG increased only around the hip extensors muscles (53%) after training (P > 0.05). No further differences were observed for the experimental and control groups in any of the other tested joints (P > 0.05).
Discussion
Figure 3 Dynamic strength (one maximal repetition test) of the (a) knee extension, (b) knee flexion and (c) leg-press exercise of the water-based group (WBG), resistance-training group (RTG) and control group pre- and post-training (mean ± standard deviation). *Post-test values greater than pretest values (P < 0.05).
50% of the plantar flexors muscles (P < 0.05), but the peak torque remained unchanged in the other muscle groups in the after training. The RTG showed 26% improvement to the peak torque of knee flexors muscles (P < 0.05), without alterations to the other muscles groups in the post-test (P > 0.05). The WBG showed the largest gains for the hip extensor (P < 0.05) and ankle plantar flexor (P < 0.05) muscles in comparison with the CG, showing an important effect of the water-based training stimulus. The MVIC results are presented in Figure 4. © 2014 Japan Geriatrics Society
The main finding of the present study was that 12 weeks of a moderate-intensity water-based program provided a similar improvement in the dynamic strength (1RM) in comparison with resistance training. The peak torque increased around the hip and ankle joints in the waterbased group, and around the knee joint in the resistance-training group. The RTD increased only in the water-based group around the hip extensors muscles. Strength gains in response to resistance training are variable across the studies, as a result of multiple factors that include: population, intensity, program duration and the initial strength levels of the participants.19 The dynamic strength improvement varied from 21% for the knee flexor muscles to 35.6% for the leg-press exercise, which are slightly smaller than that reported by other studies.7,8 Strength differences at baseline might explain the larger improvements observed in other studies.19,20 The MVIC around the knee gains in the resistance training group was not observed in other muscles. Hortobagyi et al. also failed to find changes in the MVIC, despite of the dynamic strength improvements.21 The dynamic nature of the training program (dynamic contractions) might have provided a more specific stimulus, which cannot be fully detected in static tests (i.e. by isometric tests). The rate of torque development did not change after training in the resistance-training group. The low muscle contraction velocity applied to move high resistances might explain such results. In contrast, it might have constituted a specific stimulus for improving the RTD, which requires moderate loads and fast contractions.22 The result of the present study does not support the findings of Petric et al., who compared strength gains between water-based and resistance-training programs in elderly women, and did not find improvements after training, irrespective of the program type.12 Perhaps, the lack of specificity of the tests (i.e. handgrip strength) used in that study could explain the similarities between groups, especially because most changes are likely to occur in the lower limbs. Others studies compared the effects of water- versus land-based exercises on dynamic strength; however, the participants were middleaged10,23 or suffering from health conditions, such as fibromyalgia24 or osteoarthritis,25 and were generally |
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Figure 4 Maximum voluntary isometric contraction (MVIC) of the (a) hip extension and flexion, (b) knee extension and flexion, and (c) plantar flexion and dorsi flexion of the water-based group (WBG), resistance training group (RTG) and control group (CG) pre- and post-training (mean + standard deviation). *Post-test values greater than pretest values (P < 0.05).
weaker than others with a regular health status. Thus, comparison must be viewed with caution, especially because weaker subjects tend to present larger muscle function gains.10 Two studies determined the dynamic strength of the lower limbs after water-based exercises.13,26 Takeshima et al., found strength increments for the knee extensor (8%) and flexor muscles (13%) after 12 weeks of training, which are similar to the gains detected in the present study (11.6% and 13.2%, respectively).26 Tsourlou et al. applied a training program that was very similar to ours, but observed higher increments.13 The longer duration of the training period (24 weeks) and the lack of a familiarization period could account for such discrepancies. It is well known that discarding a period of habituation might enhance performance gains and obscure comparisons.27 The MIVC increase observed in the hip extensors muscles for the water-based group (42%) was larger 6
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than that (27%) observed by Wang et al.25 The constant increases in the intensity of the exercise program (each 4 weeks) and the increased speed of movements imposed during the water-based sessions could have provided an adequate stimulus to improve muscle strength. Furthermore, the buoyancy force is an additional resistive stimulus when movements are carried out in the direction to the bottom of the swimming pool, which might at least partially explain the gains observed around the hip extensor muscles. In contrast, movements carried out upward are assisted by buoyancy force, and could clarify the lack of MIVC improvement around the hip flexor muscles.9 The MIVC of the knee extensor and flexor muscles did not change after training, and indicated that not all muscle groups respond in the same way to the exercises in the water. Indeed, the area of the more distal segments of the lower limbs is relatively small, and might not be sufficient to generate drag forces large enough to elicit resistive forces to © 2014 Japan Geriatrics Society
Muscle function: water and land exercises
Figure 5 Rate of torque development (RTD) of the (a) hip extension and flexion, (b) knee extension and flexion, and (c) plantar flexion and dorsi flexion of the water-based group (WBG), resistance training group (RTG) and control group (CG) pre- and post-training (mean + standard deviation). *Post-test values greater than pretest values (P < 0.05).
promote large strength gains, despite the use of resistance devices. The MIVC increases in the plantar-flexors muscles (50%) might be explained by the large amount of stimulus required by the displacements imposed during the water-based sessions. Furthermore, the role of the plantar-flexors muscles to maintain and recover perturbed balance as a result of the water turbulence could have been an important additional stimulus. Not surprisingly, no changes were observed around the dorsi-flexor muscles, which are far less used while walking in shallow water.28 The water-based program was effective for improving the dynamic strength of the lower limb to the same extent as that obtained from the resistance-training program. In addition, water-based programs were more suitable for promoting strength and the rate of torque development around the hip and ankle than resistance training. Thus, water-based programs constitute an attractive alternative for promoting relevant gains using moderate loads and fast speed movements, which are © 2014 Japan Geriatrics Society
also effective for improving the capacity to generate fast torques. Generating fast torques might be of decisive importance while recovering from a slip or trip, and could prevent an accidental fall.
Disclosure statement We declare that the present study did not receive any financial support or relationship that may pose potential conflicts of interest. No potential conflicts of interest were disclosed.
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© 2014 Japan Geriatrics Society
