Effects of stretching on passive muscle tension and response to eccentric exercise

Chronic effects of stretching on range of motion with consideration of potential moderating variables: A systematic review with meta-analysis

BACKGROUND

It is well known that stretch training can induce prolonged increases in joint range of motion (ROM). However, to date more information is needed regarding which training variables might have greater influence on improvements in flexibility. Thus, the purpose of this meta-analysis was to investigate the effects of stretch training on ROM in healthy participants by considering potential moderating variables, such as stretching technique, intensity, duration, frequency, and muscles stretched, as well as sex-specific, age-specific, and/or trained state-specific adaptations to stretch training.

METHODS

We searched through PubMed, Scopus, Web of Science, and SportDiscus to find eligible studies and, finally, assessed the results from 77 studies and 186 effect sizes by applying a random-effect meta-analysis. Moreover, by applying a mixed-effect model, we performed the respective subgroup analyses. To find potential relationships between stretch duration or age and effect sizes, we performed a meta-regression.

RESULTS

We found a significant overall effect, indicating that stretch training can increase ROM with a moderate effect compared to the controls (effect size = -1.002; Z = -12.074; 95% confidence interval: -1.165 to -0.840; p < 0.001; I2 = 74.97). Subgroup analysis showed a significant difference between the stretching techniques (p = 0.01) indicating that proprioceptive neuromuscular facilitation and static stretching produced greater ROM than did ballistic/dynamic stretching. Moreover, there was a significant effect between the sexes (p = 0.04), indicating that females showed higher gains in ROM compared to males. However, further moderating analysis showed no significant relation or difference.

CONCLUSION

When the goal is to maximize ROM in the long term, proprioceptive neuromuscular facilitation or static stretching, rather than ballistic/dynamic stretching, should be applied. Something to consider in future research as well as sports practice is that neither volume, intensity, nor frequency of stretching were found to play a significant role in ROM yields.

MRI T2 mapping and shear wave elastography for identifying main pain generator in delayed-onset muscle soreness: muscle or fascia?

INTRODUCTION

The main generator of delayed onset muscle soreness (DOMS) is still unknown. This study aimed to clarify the main generator of DOMS.

METHODS

Twelve participants performed eccentric exercise (EE) on lower legs. MRI and ultrasound were used to assess changes of calf muscle and deep fascia before and after EE. These results were then compared to the muscle pain level.

RESULTS

Compared to baseline, muscle pain peaked at 24-48 h after EE (downstairs 22.25 ± 6.196, 57.917 ± 9.298, F = 291.168, p < 0.01; resting 5.833 ± 1.899, 5.083 ± 2.429, F = 51.678, p < 0.01). Shear wave speed (SWE) of the deep fascia and T2 values of the gastrocnemius muscle and deep fascia all increased and peaked at 48 h after EE (1.960 ± 0.130, F = 22.293; 50.237 ± 2.963, F = 73.172; 66.328 ± 2.968, F = 231.719, respectively, p < 0.01). These measurements were positively correlated with DOMS (downstairs: r = 0.46, 0.76, 0.87, respectively, p < 0.001; resting: r = 0.42, 0.70, 0.77, respectively, p < 0.001). There was a significant positive correlation between SWE and T2 values of deep fascia (r = 0.54, p < 0.01).

CONCLUSION

DOMS is a common result of muscle and fascia injuries. Deep fascia edema and stiffness play a crucial role in DOMS, which can be effectively evaluated MR-T2 and SWE.

CRITICAL RELEVANCE STATEMENT

Delayed-onset muscle soreness is a common result of muscle and deep fascia injuries, in which the edema and stiffness of the deep fascia play a crucial role. Both MRI and shear wave elastography can be effectively used to evaluate soft tissue injuries.

KEY POINTS

• The deep fascia is the major pain generator of delayed-onset muscle soreness. • There is a significant correlation between fascia injury and delayed-onset muscle soreness. • MRI and shear wave elastography are preferred methods for assessing fascia injuries.

Acute and Long-Term Effects of Static Stretching on Muscle-Tendon Unit Stiffness: A Systematic Review and Meta-Analysis

Static stretching can increase the range of motion of a joint. Muscle-tendon unit stiffness (MTS) is potentially one of the main factors that influences the change in the range of motion after static stretching. However, to date, the effects of acute and long-term static stretching on MTS are not well understood. The purpose of this meta-analysis was to investigate the effects of acute and long-term static stretching training on MTS, in young healthy participants. PubMed, Web of Science, and EBSCO published before January 6, 2023, were searched and finally, 17 papers were included in the meta-analysis. Main meta-analysis was performed with a random-effect model and subgroup analyses, which included comparisons of sex (male vs. mixed sex and female) and muscle (hamstrings vs. plantar flexors) were also performed. Furthermore, a meta-regression was conducted to examine the effect of total stretching duration on MTS. For acute static stretching, the result of the meta-analysis showed a moderate decrease in MTS (effect size = -0.772, Z = -2.374, 95% confidence interval = -1.409 - -0.325, p = 0.018, I2 = 79.098). For long-term static stretching, there is no significant change in MTS (effect size = -0.608, Z = -1.761, 95% CI = -1.284 - 0.069, p = 0.078, I2 = 83.061). Subgroup analyses revealed no significant differences between sex (long-term, p = 0.209) or muscle (acute, p =0.295; long-term, p = 0.427). Moreover, there was a significant relationship between total stretching duration and MTS in acute static stretching (p = 0.011, R2 = 0.28), but not in long-term stretching (p = 0.085, R2 < 0.01). Whilst MTS decreased after acute static stretching, only a tendency of a decrease was seen after long-term stretching.

Potential Effects of Dynamic Stretching on Injury Incidence of Athletes: A Narrative Review of Risk Factors

The use of dynamic stretching as a replacement for static stretching in the warm-up is widespread based on the reports of static stretching-induced performance impairments. While acute and chronic static stretching has been reported to reduce musculotendinous injuries, especially with explosive and change of direction actions, the influence of dynamic stretching on injury incidence lacks a similar volume of literature for acute and chronic responses. It was the objective of this narrative review to examine the acute and training effects of dynamic stretching on injury incidence and possible moderating variables such as dynamic stretching effects on range of motion, strength, balance, proprioception, muscle morphology, and psycho-physiological responses. One study demonstrated no significant difference regarding injury incidence when comparing a dynamic stretching-only group versus a combined dynamic stretching plus static stretching group. The only other study examined functional dynamic stretching training with injured dancers and reported improved ankle joint stability. However, several studies have shown that dynamic activity with some dynamic stretching exercises within a warm-up consistently demonstrates positive effects on injury incidence. Regarding moderating variables, while there is evidence that an acute bout of dynamic stretching can enhance range of motion, the acute and training effects of dynamic stretching on strength, balance, proprioception, and musculotendinous stiffness/compliance are less clear. The acute effects of dynamic stretching on thixotropic effects and psycho-physiological responses could be beneficial for injury reduction. However, the overall conflicting studies and a lack of substantial literature compared with SS effects points to a need for more extensive studies in this area.

Effects of the COVID-19 confinement period on hip strength, flexibility and muscle injury rate in professional soccer players

OBJECTIVES

This study aimed to examine the effects of COVID-19 confinement on hamstring eccentric strength, hip adduction-abduction strength, and posterior chain flexibility in professional male soccer players. We also aimed to investigate whether muscle strength and flexibility would change when the players returned to play after COVID-19 confinement.

METHODS

Thirty professional male soccer (Age; 24.9 ± 4.8 yrs, BMI; 22.7 ± 1.4 kg/m²) players participated in this study. Hamstring eccentric strength, hip abduction-adduction strength and posterior chain flexibility (PCF) were measured before (time 1) and after the home confinement period (time 2) and after return to play (time 3). Repeated measures of ANOVA was used for statistical analysis.

RESULTS

PCF decreased from time 1 to time 2 (p = 0.005) but it increased from time 2 to time 3 (p = 0.03). Hamstring eccentric strength decreased from time 1 to time 2 for both dominant (p = 0.002) and non-dominant (p = 0.04) limbs and no difference was observed between time 2 and time 3 (p > 0.05). Hip abductor and adductor strength did not change between time 1 and time 2 (p > 0.05) but they increased from time 2 and time 3 in the dominant limb (p < 0.05). Five players (16%) had muscle injuries including hamstrings and adductors when they returned to play.

CONCLUSION

This study showed that 8-week COVID-19 confinement had an adverse effect on hamstring eccentric strength and PCF and 3 players had hamstring muscle injuries when they returned to play. Therefore, soccer players can be at risk of hamstring muscle injuries due to long-term detraining. Hip abductor and adductor strength seem not to be negatively affected by 8-week COVID-19 confinement. However, 2 players had adductor strain when they returned to play.

Effects of Different Long-Term Exercise Modalities on Tissue Stiffness

Stiffness is a fundamental property of living tissues, which may be modified by pathologies or traumatic events but also by nutritional, pharmacological and exercise interventions. This review aimed to understand if specific forms of exercise are able to determine specific forms of tissue stiffness adaptations. A literature search was performed on PubMed, Scopus and Web of Science databases to identify manuscripts addressing adaptations of tissue stiffness as a consequence of long-term exercise. Muscular, connective, peripheral nerve and arterial stiffness were considered for the purpose of this review. Resistance training, aerobic training, plyometric training and stretching were retrieved as exercise modalities responsible for tissue stiffness adaptations. Differences were observed related to each specific modality. When exercise was applied to pathological cohorts (i.e. tendinopathy or hypertension), stiffness changed towards a physiological condition. Exercise interventions are able to determine tissue stiffness adaptations. These should be considered for specific exercise prescriptions. Future studies should concentrate on identifying the effects of exercise on the stiffness of specific tissues in a broader spectrum of pathological populations, in which a tendency for increased stiffness is observed.

Description of ROM-SPORT I Battery: Keys to Assess Lower Limb Flexibility

Limited range of motion (ROM) is considered one of the most important intrinsic and modifiable risk factors for the most common sports-related injuries. In addition, controlling and monitoring an athlete's ROM is a strategy to achieve optimal ROM and improve athletic performance in sports, especially those that require high ROM in the major joints. Therefore, assessing ROM (pre-participation, during a rehabilitation process, on return to play, etc.) is important not only as a method to prevent sports injuries, but also as a quantitative determinant of the potential of athletic performance. However, despite the variety of different ROM assessment methods described in the literature, there is no consensus on which methods are best suited for this goal. Recently, the ROM-SPORT I battery has been shown to have advantages over other ROM assessment methods. This tool has not yet been fully described in detail for researchers, sports professionals, and clinicians to learn. The main objective of this study is to describe the ROM-SPORT I battery tests in detail using the following criteria: test description, simplicity of the test procedure, low need for human and material resources, predictive validity, and reliability.

Evidence-Based Hamstring Injury Prevention and Risk Factor Management: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Hamstring injuries are common among athletes. Considering the potentially prolonged recovery and high rate of recurrence, effective methods of prevention and risk factor management are of great interest to athletes, trainers, coaches, and therapists, with substantial competitive and financial implications.

PURPOSE

To systematically review the literature concerning evidence-based hamstring training and quantitatively assess the effectiveness of training programs in (1) reducing injury incidence and (2) managing injury risk factors.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 1.

METHODS

A computerized search of MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, and SPORTDiscus with manual screening of selected reference lists was performed in October 2020. Randomized controlled trials investigating methods of hamstring injury prevention and risk factor management in recreational, semiprofessional, and professional adult athletes were included.

RESULTS

Of 2602 articles identified, 108 were included. Eccentric training reduced the incidence of hamstring injury by 56.8% to 70.0%. Concentric hamstring strength increased with eccentric (mean difference [MD], 14.29 N·m; 95% CI, 8.53-20.05 N·m), concentric, blood flow-restricted, whole-body vibration, heavy back squat, FIFA 11+ (Fédération Internationale de Football Association), and plyometric training methods, whereas eccentric strength benefited from eccentric (MD, 26.94 N·m; 95% CI, 15.59-38.30 N·m), concentric, and plyometric training. Static stretching produced greater flexibility gains (MD, 10.89°; 95% CI, 8.92°-12.86°) than proprioceptive neuromuscular facilitation (MD, 9.73°; 95% CI, 6.53°-12.93°) and dynamic stretching (MD, 6.25°; 95% CI, 2.84°-9.66°), although the effects of static techniques were more transient. Fascicle length increased with eccentric (MD, 0.90 cm; 95% CI, 0.53-1.27 cm) and sprint training and decreased with concentric training. Although the conventional hamstring/quadriceps (H/Q) ratio was unchanged (MD, 0.03; 95% CI, -0.01 to 0.06), the functional H/Q ratio significantly improved with eccentric training (MD, 0.10; 95% CI, 0.03-0.16). In addition, eccentric training reduced limb strength asymmetry, while H/Q ratio and flexibility imbalances were normalized via resistance training and static stretching.

CONCLUSION

Several strategies exist to prevent hamstring injury and address known risk factors. Eccentric strengthening reduces injury incidence and improves hamstring strength, fascicle length, H/Q ratio, and limb asymmetry, while stretching-based interventions can be implemented to improve flexibility. These results provide valuable insights to athletes, trainers, coaches, and therapists seeking to optimize hamstring training and prevent injury.

Influence of Stretching Exercises, Warm-Up, or Cool-Down on the Physical Performance of Mangalarga Marchador Horses

The Horse Agribusiness Complex is an important activity in the Brazilian agricultural sector. Mangalarga Marchador (MM) is the most numerous breed of horses in Brazil and its temperament and gait characteristics (4-beat stepping gait) allow for the constant growth of the breed and the performance of vs. equestrian activities. The training management currently adopted with MM horses is based on empiricism, and scientific support is necessary to improve the well-being of horses in competitions and maintain the physical integrity of these athletes. Therefore, this study aimed to verify the effects of stretching, warming up, and/or cooling down on their performance in marcha tests. 6 MM geldings (aged between 3 and 7 years and average weight of 400 kg) were used. The pre-experimental stage for the physical conditioning of the horses lasted 46 days. The experimental phase lasted 42 days and consisted of 6 marcha tests performed every 7 days. The experimental design was in a Latin square (6 × 6), in which each horse was submitted to the following exercise protocols: A) 50-min marcha test following the official regulations of the Brazilian Association of Horse Breeders Mangalarga Marchador (ABCCMM); B) 10 min of warm-up before marcha test; C) 10 min of cooling after marcha test; D) 10 min of warm-up before marcha and 10 min of cool-down after marcha test; E) 10 min of stretching before the marcha test; F) 10 min of stretching, 10 min of warm-up before and 10 min of cool-down after the test. Horses were evaluated before and after marcha tests for heart rate (HR), respiratory rate, rectal temperature, glucose, lactate, creatine kinase, aspartate aminotransferase and cortisol. Data were submitted to 2-way analysis of variance (exercise protocols and evaluation moments) and means were compared by Tukey's test (P≤0.05). The HR and blood lactate results indicated a beneficial effect of warm-up or stretching practices on the performance of Mangalarga Marchador horses submitted to simulated marcha tests in accordance with the official ABCCMM regulation and lasting 50 minutes.

Chronic Effects of a Static Stretching Program on Hamstring Strength

ABSTRACT

Nakao, S, Ikezoe, T, Nakamura, M, Umegaki, H, Fujita, K, Umehara, J, Kobayashi, T, Ibuki, S, and Ichihashi, N. Chronic effects of a static stretching program on hamstring strength. J Strength Cond Res 35(7): 1924-1929, 2021-This study investigated the effects of a 4-week static stretching (SS) program on isokinetic and isometric knee flexor peak torque and angle of peak torque. Thirty healthy men (age, 22.7 ± 2.2 years) were randomized to receive either of the following: (a) a 4-week stretch intervention for the hamstrings (SS intervention group; n = 15) or (b) no intervention (control group; n = 15). The maximum pain-free knee angle, passive stiffness, which was determined by a slope of torque-angle curve, isometric and isokinetic (at 60°·s-1 and 180°·s-1) peak torque, and angle of peak torque for knee flexors were measured before and after 4 weeks. After 4 weeks, passive stiffness decreased significantly in the intervention group. There were no significant changes in isometric and isokinetic (neither at 60°·s-1 nor at 180°·s-1) peak torque, or angle of peak torque at 180°·s-1. A significantly increased peak extension angle at 60°·s-1 was observed in the intervention group. These results suggest that SS intervention is effective for decreasing musculotendinous unit stiffness of the hamstrings and that an SS program influences the angle of peak torque, whereas no significant changes occur in peak torque. Because a previous study suggests that angle of peak torque is associated with hamstring strain injuries, the results of this study would be helpful when considering the training program for preventing or treating hamstring strain injuries.

Dynamic transcriptome and histomorphology analysis of developmental traits of hindlimb thigh muscle from Odorrana tormota and its adaptability to different life history stages

Background

Systematic studies on the development and adaptation of hindlimb muscles in anura amphibians are rare. Here, we integrated analysis of transcriptome and histomorphological data for the hindlimb thigh muscle of Odorrana tormota (concave-eared torrent frog) at different developmental stages, to uncover the developmental traits of hindlimb thigh muscle from O. tormota and its adaptability to different life history stages.

Results

The development of hindlimb thigh muscle from O. tormota has the following characteristics. Before metamorphosis, myogenous cells proliferate and differentiate into myotubes, and form 11 muscle groups at G41; Primary myofibers and secondary myofibers appeared during metamorphosis; 11 muscle groups differentiated continuously to form myofibers, accompanied by myofibers hypertrophy after metamorphosis; During the growth process of O. tormota from G42 to G46, there were differences between the sexes in the muscle groups that differentiate into muscle fibers, indicating that there was sexual dimorphism in the hindlimb thigh muscles of O. tormota at the metamorphosis stages. Some genes and pathways related to growth, development, and movement ability of O. tormota at different developmental stages were obtained. In addition, some pathways associated with adaptation to metamorphosis and hibernation also were enriched. Furthermore, integrated analysis of the number of myofibers and transcriptome data suggested that myofibers of specific muscle groups in the hindlimbs may be degraded through lysosome and ubiquitin pathways to transform into energy metabolism and other energy-related substances to meet the physiological needs of hibernation.

Conclusions

These results provide further understanding the hindlimb thigh muscle development pattern of frogs and their adaption to life history stages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07677-0.

Effectiveness of Heel-Raise-Lower Exercise after Transcutaneous Electrical Nerve Stimulation in Patients with Stroke: A Randomized Controlled Study

OBJECTIVE

This study was conducted to investigate the effect of the heel-raise-lower exercise on spasticity, strength, and gait speed after the application of 30 min of transcutaneous electrical nerve stimulation (TENS) in patients with stroke.

METHODS

The participants were randomly divided into the TENS group and the placebo group, with 20 participants assigned to each group. In the TENS group, heel-raise-lower exercise was performed after applying TENS for six weeks. The placebo group was trained in the same manner for the same amount of time but without electrical stimulation. The spasticity of the ankle plantar flexors was measured using the composite spasticity score. A handheld dynamometer and a 10-m walk test were used to evaluate muscle strength and gait speed, respectively.

RESULTS

Spasticity was significantly more improved in the TENS group (mean change -2.0 ± 1.1) than in the placebo group (mean change -0.4 ± 0.9) (p < 0.05). Similarly, muscle strength was significantly more improved in the TENS group (6.4 ± 3.3 kg) than in the placebo group (4.5 ± 1.6 kg) (p < 0.05). Moreover, participants assigned to the TENS group showed a significant greater improvement in gait speed than those in the placebo group (mean change -5.3 ± 1.4 s vs. -2.7 ± 1.2 s).

CONCLUSIONS

These findings show the benefits of heel-raise-lower exercise after TENS for functional recovery in patients with stroke.

Effect of Static Stretching, Dynamic Stretching, and Myofascial Foam Rolling on Range of Motion During Hip Flexion: A Randomized Crossover Trial

Siebert, T, Donath, L, Borsdorf, M, and Stutzig, N. Effect of static stretching, dynamic stretching, and myofascial foam rolling on range of motion during hip flexion: A randomized crossover trial. J Strength Cond Res XX(X): 000-000, 2020-Static and dynamic stretching (DS) are commonly used in sports and physical therapy to increase the range of motion (ROM). However, prolonged static stretching (SS) can deteriorate athletic performance. Alternative methods to increase ROM are thus needed. Foam rolling (FR) may initiate muscle relaxation, improve muscular function, physical performance, and ROM. Previous studies that examined effects of FR on ROM did not control for increased tissue compliance or shifted pain threshold. In this study, the isolated influence of altered tissue compliance on ROM after FR, SS, and DS was investigated using a randomized crossover design. Hip flexion ROM at given joint torques before and after SS, DS, and FR was randomly assessed in 14 young male adults (age: 23.7 +/- 1.3 years; height: 182 +/- 8 cm; body mass: 79.4 +/- 6.9 kg). Hip flexion ROM was measured in the sagittal plane with the subjects lying in a lateral position (no gravitational effects on ROM measurements). Surface electromyographic (EMG) analysis of 2 representative hip extensors (M. biceps femoris and M. semitendinosus) was applied to control for active muscle contribution during ROM measurements. Significant increases in ROM for SS (3.8 +/- 1.1[degrees]; p < 0.001) and DS (3.7 +/- 1.8[degrees]; p < 0.001) were observed, but not for FR (0.8 +/- 3.1[degrees]; p = 0.954). Because stretch forces on tendon and muscle tissue during SS and DS predominately act in longitudinal direction, FR induces mainly transversal forces in the muscle tissue. Thus, increased ROM after FR reported in the literature is more likely due to a shift in the pain threshold. These results provide a better understanding of differential loading conditions during SS, DS, and FR for coaches and practitioners.

Immediate Effects of Dry Needling as a Novel Strategy for Hamstring Flexibility: A Single-Blinded Clinical Pilot Study

CONTEXT

There are numerous studies on the benefits of dry needling (DN) for pain relief. No studies exist examining the effects of DN on hamstring flexibility.

OBJECTIVE

To determine the immediate effects of DN on hamstring flexibility in healthy subjects with shortened hamstrings.

DESIGN

A single-blinded, pretest-posttest clinical pilot study.

SETTING

A university physiotherapy clinic.

SUBJECTS

A total of 15 healthy subjects (female = 11; age = 23.26 [4.3] y) with shortened hamstrings participated in this study.

INTERVENTION

Subjects received a single session of DN. Three locations on the hamstring muscle group were needled, each for 1 minute.

MAIN OUTCOME MEASURES

The active knee extension test, muscle compliance, passive peak torque, and stretch tolerance were measured at baseline, immediately, and 15 minutes after DN.

RESULTS

There were statistically significant improvements in all outcome measures immediately after DN and at the 15-minute follow-up. The effect sizes for all outcome measures were large (Cohen's d ≥ 0.8). No serious adverse events were observed with DN.

CONCLUSIONS

This is the first study that demonstrates the beneficial effects of DN on hamstring flexibility, muscle compliance, and stretch tolerance without added stretching. The beneficial effects of DN should encourage clinicians to use DN as a novel strategy for increasing muscle flexibility.

The effects of 6 weeks of constant-angle muscle stretching training on flexibility and muscle function in men with limited hamstrings' flexibility

PURPOSE

The aim of the present study was to evaluate the effects of 6 weeks of a constant-angle hamstring muscle flexibility training on muscle-tendon stiffness and the range of motion (ROM) in young men with limited hamstring ROM.

METHODS

13 participants performed unilateral stretching training (EL), while the contralateral limb acted as control (CL). ROM, relative and peak passive torque, passive stiffness, dynamic knee flexion strength, and active optimum joint angle were assessed before and after the last training session. In addition, participants were tested during the first and last training sessions for first stretch sensation during the stretching procedure only in the EL.

RESULTS

Straight-leg raise and isokinetic knee ROM tests (both p < 0.0001; from 59.4 ± 8.1 to 70.3 ± 9.8, from 28.3 ± 7.6 to 18.5 ± 5.2, respectively) and peak passive torque (p = 0.001; from 53.1 ± 11.7 to 64.9 ± 12.3) increased only in EL and no changes in relative passive torque, passive stiffness, dynamic knee flexion strength, and active optimum joint angle (p > 0.05) were observed. At the point of first stretch sensation, significant increases in passive torque (p = 0.004) and angle (p < 0.001) were found from pre- to post-training.

CONCLUSION

The flexibility training induced significant increases in ROM alongside increases in peak passive torque (stretch tolerance) and the ROM at which stretch was first perceived. However, this occurred without changes in muscle-tendon mechanical properties or transfer to the untrained limb (CL). These results suggest that limb-specific ROM increases were underpinned by neural adaptations.

Effects of cold water immersion and compression garment use after eccentric exercise on recovery

[Purpose]

The combined effect of different types of post-exercise treatment has not been fully explored. We investigated the effect of combined cold water immersion (CWI) and compression garment (CG) use after maximal eccentric exercise on maximal muscle strength, indirect muscle damage markers in the blood, muscle thickness, and muscle soreness score 24 h after exercise.

[Methods]

Ten men performed two trials (CWI + CG and CON) in random order. In the CWI + CG trial, the subjects performed 15 min of CWI (15°C), followed by wearing of a lower-body CG for 24 h after exercise. In the CON trial, there was no post-exercise treatment. The exercise consisted of 6 × 10 maximal isokinetic (60°·s^-1) eccentric knee extensions using one lower limb. The maximal voluntary contraction (MVC) and maximal isokinetic (60°·s^-1) strength during knee extension, as well as the indirect muscle damage markers, were evaluated before exercise and 24 h after exercise.

[Results]

The maximal muscle strength decreased in both trials (p < 0.001), with no difference between them. The exercise-induced elevation in the myoglobin concentration tended to be lower in the CWI + CG trial than in the CON trial (p = 0.060). The difference in the MVC, maximal isokinetic strength, muscle thickness, and muscle soreness score between the trials was not significant.

[Conclusion]

CWI followed by wearing of a CG after maximal eccentric exercise tended to attenuate the exercise-induced elevation of indirect muscle damage markers in the blood.

Immediate effects and one-week follow-up after neuromuscular electric stimulation alone or combined with stretching on hamstrings extensibility in healthy football players with hamstring shortening

OBJECTIVE

To assess the immediate and mid-term (after 7 days) effects of electric current combined with simultaneous muscle stretching (EME technique) per comparison to the isolated use of the same current (without applying simultaneous muscle stretching), over the hamstring extensibility in football players with hamstring shortening, and to estimate the clinical benefit of the interventions according to the muscular extensibility.

METHODS

Forty-eight participants were randomized to receive one session of EME technique (n = 26) or one session of the electrical current (EC) alone (n = 22). The measurement of the hamstrings extensibility through the active knee test was carried out before and immediately after each intervention and one week later.

RESULTS

A significant interaction group x time was observed (F_2,84 = 7.112, p = 0.001; partial eta squared = 0.145). The hamstrings extensibility changed significantly immediately after the EME technique (147.3° ± 16.4° to 153.5° ± 14.2°, p < 0.05), but not after the EC only (144.2 ± 10.2° to 141.7 ± 7.8°, p > 0.05). One week after the intervention no significant differences were found to the baseline values in both groups. The number needed to treat to prevent one new case of hamstring shortening was 3.

CONCLUSION

The combination of electric current with simultaneous stretching is an effective technique to acutely increase the hamstring extensibility of football players with hamstring shortness.

Adaptations in the passive mechanical properties of skeletal muscle to altered patterns of use

The aim of this mini-review is to describe the present state of knowledge regarding the effects of chronic changes in the patterns of muscle use (defined as changes lasting >1 wk), including muscle stretching, strengthening, and others, on the passive mechanical properties of healthy human skeletal muscles. Various forms of muscle stretch training and some forms of strength training (especially eccentric training) are known to strongly impact the maximum elongation capacity of muscles in vivo (i.e., maximum joint range of motion), largely by increasing our ability to tolerate higher stretch loads. However, only small effects are observed in the passive stiffness of the muscle-tendon unit (MTU) or the muscle itself, although a reduction in muscle stiffness has been observed in the plantar flexors after both stretching and eccentric exercise interventions. No changes have yet been observed in viscoelastic properties such as the MTU stress-relaxation response, although a minimum of evidence indicates that hysteresis during passive stretch-relaxation cycles may be reduced by muscle stretching training. Importantly, data exist for relatively few muscle groups, and little is known about the effects of age and sex on the adaptive process of passive mechanical properties. Despite the significant research effort afforded to understanding the effects of altered physical activity patterns on the maximum range of motion at some joints, further information is needed before it will be possible to develop targeted physical activity interventions with the aim of evoking specific changes in passive mechanical properties in individuals or in specific muscles and muscle groups.

Balance highly influences flexibility measured by the toe-touch test

Flexibility evaluation is a standard assessment in clinical and in sports settings. The Toe-touch test (TTT) is a common assessment tool to evaluate posterior muscular chain flexibility, but the test procedure implies a balance demand. The objective of the study was to verify the hypothesis that the balance demand during the TTT may affect the flexibility measured by the test. Twenty healthy, active young adults participated in the present study. Toe-touch test outcome (the linear finger to toe distance), Center of Pressure (CP) and sagittal plane joint angles were compared under two balance conditions: (1) standard TTT (ST) and (2) minimised postural demand (MPD) during TTT (using a device that restrained the participant against a forward fall). Then, ST was re-tested to verify a possible effect of motor learning on TTT outcome. Compared to ST, MPD showed an improvement of 73% in test outcome, greater flexion of the ankle, greater total body flexion, and a forward displacement of the CP. Re-test of ST showed indications of motor learning with a different balance strategy compared to the first trial in the same condition. The test outcome showed significant negative correlations with CP position in ST (weak correlation), in the re-test (strong correlation) and when the conditions were combined (moderate correlation). In conclusion, TTT outcome was highly affected by balance performance. Maximum range of motion during ST was a fraction of the range obtained when balance demand was minimized.

The effects of flexibility training on exercise-induced muscle damage in young men with limited hamstrings flexibility

Adaptations to 6 weeks of supervised hamstring stretching training and its potential impact on symptoms of eccentric exercise-induced muscle damage (EIMD) were studied in 10 young, untrained men with limited hamstrings flexibility. Participants performed unilateral flexibility training (experimental leg; EL) on an isokinetic dynamometer, while the contralateral limb acted as control (CL). Hip range of motion (ROM), passive, isometric, and concentric torques, active optimum angle, and biceps femoris and semitendinosus muscle thickness and ultrasound echo intensity were assessed both before and after the training. Additionally, muscle soreness was assessed before and after an acute eccentric exercise bout in both legs (EL and CL) at post-training only. Hip ROM increased (P < .001) only in EL after the training (EL = 10.6° vs CL = 1.6°), but no changes (P > .05) in other criterion measurements were observed. After a bout of eccentric exercise at the end of the program, isometric and dynamic peak torques and muscle soreness ratings were significantly altered at all time points equally in EL and CL. Also, active optimum angle was reduced immediately, 48 and 72 hours post-exercise, and hip ROM was reduced at 48 and 72 hours equally in EL and CL. Finally, biceps femoris muscle thickness was significantly increased at all time points, and semitendinosus thickness and echo intensity significantly increased at 72 hours, with no significant differences between legs. The stretching training protocol significantly increased hip ROM; however, it did not induce a protective effect on EIMD in men with tight hamstrings.

The Efficacy of Dynamic Contract-Relax Stretching on Delayed-Onset Muscle Soreness Among Healthy Individuals: A Randomized Clinical Trial

OBJECTIVE

To evaluate the efficacy of dynamic contract-relax stretching on delayed-onset muscle soreness (DOMS) in the calf muscle of healthy individuals.

DESIGN

Randomized clinical trial.

SETTING

Research laboratory.

PARTICIPANTS

Three groups of 16 healthy participants (n = 48) were recruited by convenience sampling.

INTERVENTIONS

Three sets of resisted bilateral heel-raising exercises until exhaustion were conducted to initiate DOMS. Participants were randomly allocated into control group without any interventions, dynamic contract-relax stretching (DS), or static stretching (SS) groups. Dynamic contract-relax stretching and SS groups performed DS and SS, respectively, on the dominant leg twice a day for 5 consecutive days (before time points of outcome measurements at 24, 48, 72, 96, and 120 hours postexercise, respectively).

MAIN OUTCOME MEASURES

Muscle soreness, lower leg girth, pressure pain threshold (PPT), range of motion (ROM), and muscle strength were measured before exercise, immediately after, and at 24, 48, 72, 96, and 120 hours postexercise.

RESULTS

There was a significant effect of time in all outcome measures including muscle soreness, lower leg girth, PPT, ROM, and muscle strength; however, there were no significant group differences or group by time interactions.

CONCLUSIONS

The effect of DS on relieving DOMS in the calf muscle is insignificant in this study. Further evidence is needed to prove the efficacy of DS on DOMS.

CLINICAL RELEVANCE

Stretching is commonly recommended before and after exercise; however, this study showed no significant impact of DS or SS in treating DOMS.

Can chronic stretching change the muscle-tendon mechanical properties? A review

It is recognized that stretching is an effective method to chronically increase the joint range of motion. However, the effects of stretching training on the muscle-tendon structural properties remain unclear. This systematic review with meta-analysis aimed to determine whether chronic stretching alter the muscle-tendon structural properties. Published papers regarding longitudinal stretching (static, dynamic and/or PNF) intervention (either randomized or not) in humans of any age and health status, with more than 2 weeks in duration and at least 2 sessions per week, were searched in PubMed, PEDro, ScienceDirect and ResearchGate databases. Structural or mechanical variables from joint (maximal tolerated passive torque or resistance to stretch) or muscle-tendon unit (muscle architecture, stiffness, extensibility, shear modulus, volume, thickness, cross-sectional area, and slack length) were extracted from those papers. A total of 26 studies were selected, with a duration ranging from 3 to 8 weeks, and an average total time under stretching of 1165 seconds per week. Small effects were seen for maximal tolerated passive torque, but trivial effects were seen for joint resistance to stretch, muscle architecture, muscle stiffness, and tendon stiffness. A large heterogeneity was seen for most of the variables. Stretching interventions with 3- to 8-week duration do not seem to change either the muscle or the tendon properties, although it increases the extensibility and tolerance to a greater tensile force. Adaptations to chronic stretching protocols shorter than 8 weeks seem to mostly occur at a sensory level.

The effect of age on hamstring passive properties after a 10-week stretch training

[Purpose] Degenerative changes take place in the musculoskeletal system of elderly people, resulting in a reduced range of motion. For this reason, stretch training is recommended for elderly individuals. To date, there have been no studies of the adaptations of the passive properties of muscles following long-term stretch training. The aim of this study is to investigate the hamstring elasticity of elderly people following a 10-week stretch training and compare the results to a younger cohort. [Subjects and Methods] The experimental groups consisted of 15 younger (24.0 ± 4.0 years) and 14 older (65.1 ± 7.9 years) individuals. Both experimental groups undertook a standardised 10-week static passive hamstring stretch training. Passive properties of the hamstring were measured with an instrumented Straight Leg Raise Test. [Results] After a 10-week stretch training, there were increases in range of motion, passive resistive force and passive elastic energy in both age groups. Passive elastic stiffness decreased. Changes of hamstring passive properties did not differ significantly between age groups after a 10-week stretch training. [Conclusion] Increasing age has a negative effect on muscle passive properties, but older individuals benefit from regular stretch training, just as younger individuals do.

Exploratory factor analysis for differentiating sensory and mechanical variables related to muscle-tendon unit elongation

Background

Stretching exercises are able to promote adaptations in the muscle-tendon unit (MTU), which can be tested through physiological and biomechanical variables. Identifying the key variables in MTU adaptations is crucial to improvements in training.

Objective

To perform an exploratory factor analysis (EFA) involving the variables often used to evaluate the response of the MTU to stretching exercises.

Method

Maximum joint range of motion (ROM_MAX), ROM at first sensation of stretching (FST_ROM), peak torque (torque_MAX), passive stiffness, normalized stiffness, passive energy, and normalized energy were investigated in 36 participants during passive knee extension on an isokinetic dynamometer. Stiffness and energy values were normalized by the muscle cross-sectional area and their passive mode assured by monitoring the EMG activity.

Results

EFA revealed two major factors that explained 89.68% of the total variance: 53.13% was explained by the variables torque_MAX, passive stiffness, normalized stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was explained by the variables ROM_MAX and FST_ROM.

Conclusion

This result supports the literature wherein two main hypotheses (mechanical and sensory theories) have been suggested to describe the adaptations of the MTU to stretching exercises. Contrary to some studies, in the present investigation torque_MAX was significantly correlated with the variables of the mechanical theory rather than those of the sensory theory. Therefore, a new approach was proposed to explain the behavior of the torque_MAX during stretching exercises.

Plantarflexor passive-elastic properties related to BMI and walking performance in older women

The objective of this study was to examine the influence of BMI on the passive-elastic properties of the ankle plantarflexors in older women. Twenty-three women, 65-80 yr, were separated into normal weight (NW, BMI <25.0kgm-2, n=11) and overweight-obese (OW, BMI≥25.0kgm-2, n=12) groups. Resistive torque of the ankle plantarflexors was recorded on an isokinetic dynamometer by passively moving the ankle into dorsiflexion. Stiffness, work absorption, and hysteresis were calculated across an ankle dorsiflexion angle of 10-15°. Maximal plantarflexor strength was assessed, then participants walked at maximal speed on an instrumented gait analysis treadmill while muscle activation (EMG) was recorded. Plantarflexor stiffness was 34% lower in OW (26.4±12.7Nmrad-1) than NW (40.0±15.7Nmrad-1, p=0.032). Neither work absorption nor hysteresis were different between OW and NW. Stiffness per kg was positively correlated to strength (r=0.66, p<0.001), peak vertical ground reaction force during walking (r=0.72, p<0.001), weight acceptance rate of force (r=0.51, p=0.007), push-off rate of force (r=0.41, p=0.026), maximal speed (r=0.61, p=0.001), and inversely correlated to BMI (r=-0.61, p=0.001), and peak plantarflexor EMG (r=-0.40, p=0.046). Older women who are OW have low plantarflexor stiffness, which may limit propulsive forces during walking and necessitate greater muscle activation for active force generation.

Hamstring-and-Lower-Back Flexibility in Male Amateur Soccer Players

OBJECTIVE

This study investigated the hamstring-and-lower-back flexibility (HLBF) of male adult amateur soccer players, using the sit-and-reach test (SRT), with a view to obtaining population-based reference values and to determining whether SRT scores are associated with player characteristics.

DESIGN

Cross-sectional cohort study.

SETTING

Teams from high-level Dutch amateur soccer competitions were recruited for participation.

PARTICIPANTS

Dutch male high-level amateur field soccer players (n = 449) of age 18 to 40 years. Players with a hamstring injury at the moment of SRT-measurement or any other injury that prevented them from following the SRT protocol were excluded.

MAIN OUTCOME MEASURES

Sit-and-reach test scores were measured and then population-based reference values were calculated as follows: >2SD below mean (defining "very low" HLBF), 1SD-2SD below mean ("low" HLBF), 1SD below mean to 1SD above mean ("normal" HLBF), 1SD-2SD above mean ("high" HLBF), and >2SD above mean ("very high" HLBF). Whether SRT scores were correlated with player characteristics was determined using a Pearson correlation coefficient or Spearman rho.

RESULTS

Sit-and-reach test scores ranged from 0 to 43.5 cm (mean 22.0 cm, SD 9.2). The cutoff points for population-based reference values were <3.5 cm for "very low", 3.5 to 13.0 cm for "low", 13.0 to 31.0 cm for "normal", 31.0 to 40.5 cm for "high", and >40.5 cm for "very high". Sit-and-reach test scores were significantly associated with players' height (ρ = -0.132, P = 0.005), body mass index (r = 0.114, P = 0.016), and history of anterior cruciate ligament surgery (P < 0.001).

CONCLUSIONS

This study is the first to describe the HLBF of amateur soccer players. The SRT reference values with cutoff points may facilitate evidence-based decision making regarding HLBF, and the SRT might be a useful tool to assess injury risk, performance, or for diagnostic purposes.

The relevance of stretch intensity and position-a systematic review

Stretching exercises to increase the range of motion (ROM) of joints have been used by sports coaches and medical professionals for improving performance and rehabilitation. The ability of connective and muscular tissues to change their architecture in response to stretching is important for their proper function, repair, and performance. Given the dearth of relevant data in the literature, this review examined two key elements of stretching: stretch intensity and stretch position; and their significance to ROM, delayed onset muscle soreness (DOMS), and inflammation in different populations. A search of three databases, Pub-Med, Google Scholar, and Cochrane Reviews, identified 152 articles, which were subsequently categorized into four groups: athletes (24), clinical (29), elderly (12), and general population (87). The use of different populations facilitated a wider examination of the stretching components and their effects. All 152 articles incorporated information regarding duration, frequency and stretch position, whereas only 79 referred to the intensity of stretching and 22 of these 79 studies were deemed high quality. It appears that the intensity of stretching is relatively under-researched, and the importance of body position and its influence on stretch intensity, is largely unknown. In conclusion, this review has highlighted areas for future research, including stretch intensity and position and their effect on musculo-tendinous tissue, in relation to the sensation of pain, delayed onset muscle soreness, inflammation, as well as muscle health and performance.

Intermittent stretch training of rabbit plantarflexor muscles increases soleus mass and serial sarcomere number

In humans, enhanced joint range of motion is observed after static stretch training and results either from an increased stretch tolerance or from a change in the biomechanical properties of the muscle-tendon unit. We investigated the effects of an intermittent stretch training on muscle biomechanical and structural variables. The left plantarflexors muscles of seven anesthetized New Zealand (NZ) White rabbits were passively and statically stretched three times a week for 4 wk, while the corresponding right muscles were used as nonstretched contralateral controls. Before and after the stretching protocol, passive torque produced by the left plantarflexor muscles as a function of the ankle angle was measured. The left and right plantarflexor muscles were harvested from dead rabbits and used to quantify possible changes in muscle structure. Significant mass and serial sarcomere number increases were observed in the stretched soleus but not in the plantaris or medial gastrocnemius. This difference in adaptation between the plantarflexors is thought to be the result of their different fiber type composition and pennation angles. Neither titin isoform nor collagen amount was modified in the stretched compared with the control soleus muscle. Passive torque developed during ankle dorsiflexion was not modified after the stretch training on average, but was decreased in five of the seven experimental rabbits. Thus, an intermittent stretching program similar to those used in humans can produce a change in the muscle structure of NZ White rabbits, which was associated in some rabbits with a change in the biomechanical properties of the muscle-tendon unit.

Passive stiffness of hindlimb muscles in anurans with distinct locomotor specializations

Anurans (frogs and toads) have been shown to have relatively compliant skeletal muscles. Using a meta-analysis of published data we have found that muscle stiffness is negatively correlated with joint range of motion when examined across mammalian, anuran and bird species. Given this trend across a broad phylogenetic sample, we examined whether the relationship held true within anurans. We identified four species that differ in preferred locomotor mode and hence joint range of motion (Lithobates catesbeianus, Rhinella marina, Xenopus laevis and Kassina senegalensis) and hypothesized that smaller in vivo angles (more flexed) at the knee and ankle joint would be associated with more compliant extensor muscles. We measured passive muscle tension during cyclical stretching (20%) around L0 (sarcomere lengths of 2.2 μm) in fiber bundles extracted from cruralis and plantaris muscles. We found no relationship between muscle stiffness and range of motion for either muscle-joint complex. There were no differences in the passive properties of the cruralis muscle among the four species, but the plantaris muscles of the Xenopus and Kassina were significantly stiffer than those of the other two species. Our results suggest that in anurans the stiffness of muscle fibers is a relatively minor contributor to stiffness at the level of joints and that variation in other anatomical properties including muscle-tendon architecture and joint mechanics as well as active control likely contribute more significantly to range of motion during locomotion.

Short term effectiveness of neural sliders and neural tensioners as an adjunct to static stretching of hamstrings on knee extension angle in healthy individuals: A randomized controlled trial

OBJECTIVE

To investigate the added benefit of nerve-biased interventions over static stretching in hamstring flexibility and to compare the effectiveness of two types of nerve-biased interventions over a week.

DESIGN

Three-arm assessor-blinded randomized controlled trial.

SETTING

University Laboratory.

PARTICIPANTS

Sixty healthy individuals (mean age = 22 ± 2.4 years) with reduced hamstring flexibility were randomized to three groups who received static stretching and neurodynamic sliders (NS-SS); static stretching with neurodynamic tensioner (NT-SS) and static stretching (SS) alone.

OUTCOME MEASURE

Knee extension angle (KEA) in degrees.

RESULTS

Baseline characteristics including demographic, anthropomorphic and KEA between groups were comparable. A significant interaction was observed between group (intervention) and time, [F (2,114) = 3.595; p = 0.031]. Post-hoc pairwise comparisons analyses revealed significant differences at post-intervention measurement time point between NS-SS and SS (mean difference: -6.8; 95%CI = -12, -1.5; p = 0.011) and NT-SS and SS (mean difference: -11.6; 95%CI = -16.7, -6.3; p < 0.001). However there was no significant difference between NS-SS and NT-SS groups (mean difference: 4.8; 95%CI = 0.4, 9.9; p = 0.074).

CONCLUSIONS

Neural sliders and tensioners are both effective in increasing hamstring flexibility as an adjunct to static hamstring stretching when compared to static stretching alone. No neural mobilization technique proved to be superior over another.

CLINICAL TRIAL REGISTRATION

This clinical trial is registered in Clinical Trials Registry- India (CTRI) with registration number CTRI/2012/05/002619.

Effects of muscle injury severity on localized bioimpedance measurements

Muscle injuries in the lower limb are common among professional football players. Classification is made according to severity and is diagnosed with radiological assessment as: grade I (minor strain or minor injury), grade II (partial rupture, moderate injury) and grade III (complete rupture, severe injury). Tetrapolar localized bioimpedance analysis (BIA) at 50 kHz made with a phase-sensitive analyzer was used to assess damage to the integrity of muscle structures and the fluid accumulation 24 h after injury in 21 injuries in the quadriceps, hamstring and calf, and was diagnosed with magnetic resonance imaging (MRI). The aim of this study was to identify the pattern of change in BIA variables as indicators of fluid [resistance (R)] and cell structure integrity [reactance (Xc) and phase angle (PA)] according to the severity of the MRI-defined injury. The % difference compared to the non-injured contralateral muscle also measured 24-h after injury of R, Xc and PA were respectively: grade I (n = 11; -10.4, -17.5 and -9.0%), grade II (n = 8; -18.4, -32.9 and -16.6%) and grade III (n = 2; -14.1, -52.9 and -43.1%), showing a greater significant decrease in Xc (p < 0.001). The greatest relative changes were in grade III injuries. However, decreases in R, that indicate fluid distribution, were not proportional to the severity of the injury. Disruption of the muscle structure, demonstrated by the localized determination of Xc, increased with the severity of muscle injury. The most significant changes 24 h after injury was the sizeable decrease in Xc that indicates a pattern of disrupted soft tissue structure, proportional to the severity of the injury.

Acute effects of static active or dynamic active stretching on eccentric-exercise-induced hamstring muscle damage

OBJECTIVES

To examine whether an acute bout of active or dynamic hamstring-stretching exercises would reduce the amount of muscle damage observed after a strenuous eccentric task and to determine whether the stretching protocols elicit similar responses.

DESIGN

A randomized controlled clinical trial.

METHODS

Thirty-six young male students performed 5 min of jogging as a warm-up and were allocated to 1 of 3 groups: 3 min of static active stretching (SAS), 3 min of dynamic active stretching (DAS), or control (CON). All subjects performed eccentric exercise immediately after stretching. Heart rate, core temperature, maximal voluntary isometric contraction, passive hip flexion, passive hamstring stiffness (PHS), plasma creatine kinase activity, and myoglobin were recorded at prestretching, at poststretching, and every day after the eccentric exercises for 5 d.

RESULTS

After stretching, the change in hip flexion was significantly higher in the SAS (5°) and DAS (10.8°) groups than in the CON (-4.1°) group. The change in PHS was significantly higher in the DAS (5.6%) group than in the CON (-5.7%) and SAS (-6.7%) groups. Furthermore, changes in muscle-damage markers were smaller in the SAS group than in the DAS and CON groups.

CONCLUSIONS

Prior active stretching could be useful for attenuating the symptoms of muscle damage after eccentric exercise. SAS is recommended over DAS as a stretching protocol in terms of strength, hamstring range of motion, and damage markers.

Use it or lose it: multiscale skeletal muscle adaptation to mechanical stimuli

Skeletal muscle undergoes continuous turnover to adapt to changes in its mechanical environment. Overload increases muscle mass, whereas underload decreases muscle mass. These changes are correlated with, and enabled by, structural alterations across the molecular, subcellular, cellular, tissue, and organ scales. Despite extensive research on muscle adaptation at the individual scales, the interaction of the underlying mechanisms across the scales remains poorly understood. Here, we present a thorough review and a broad classification of multiscale muscle adaptation in response to a variety of mechanical stimuli. From this classification, we suggest that a mathematical model for skeletal muscle adaptation should include the four major stimuli, overstretch, understretch, overload, and underload, and the five key players in skeletal muscle adaptation, myosin heavy chain isoform, serial sarcomere number, parallel sarcomere number, pennation angle, and extracellular matrix composition. Including this information in multiscale computational models of muscle will shape our understanding of the interacting mechanisms of skeletal muscle adaptation across the scales. Ultimately, this will allow us to rationalize the design of exercise and rehabilitation programs, and improve the long-term success of interventional treatment in musculoskeletal disease.

Eight weeks of dynamic stretching during warm-ups improves jump power but not repeated or single sprint performance

There is abundant research involving the acute effects of stretching on subsequent performance; however, there is little information on dynamic stretch training programmes on range of motion (ROM), power and speed measures. It was the objective of this research to examine the training consequences of active dynamic stretching (ADS) and static dynamic stretching (SDS). A repeated measures design compared the effects of 8 weeks of warm-ups incorporating two dynamic stretch modalities: ADS and SDS on squat jump (SJ), countermovement jump (CMJ), 20-m sprint performances and repeated sprint ability (RSA) and hip ROM in 37 male soccer players. SJ height (SDS: 4.6%; ADS: 5.3%; p <0.05), CMJ height (SDS: 5.3%; ADS: 3.4%; p<0.05), CMJ force (SDS: 7.2%; ADS: 12.7%; p<0.001) and CMJ peak power (SDS: 3.9%; ADS: 3.3%; p<0.05) increased significantly after SDS and ADS training compared to the control group (no significant change). Sprint performance and RSA were not affected by either of the dynamic stretch training regimens. The SDS and ADS training programmes elicited similar improvements in flexibility (SDS: 57.6%; ADS: 45.1%; p<0.01) compared to the non-significant changes in the control group. The inclusion of ADS and SDS within the regular warm-up of an 8-week training programme can improve not only flexibility but also jump power measures as well.

Effect of cryotherapy on muscle recovery and inflammation following a bout of damaging exercise

The purpose of this study was to determine the effect of cryotherapy on the inflammatory response to muscle-damaging exercise using a randomized trial. Twenty recreationally active males completed a 40-min run at a -10 % grade to induce muscle damage. Ten of the subjects were immersed in a 5 °C ice bath for 20 min and the other ten served as controls. Knee extensor peak torque, soreness rating, and thigh circumference were obtained pre- and post-run, and 1, 6, 24, 48, and 72 h post-run. Blood samples were obtained pre- and post-run, and 1, 6 and 24 h post-run for assay of plasma chemokine ligand 2 (CCL2). Peak torque decreased from 270 ± 57 Nm at baseline to 253 ± 65 Nm post-run and increased to 295 ± 68 Nm by 72 h post-run with no differences between groups (p = 0.491). Soreness rating increased from 3.6 ± 6.0 mm out of 100 mm at baseline to 47.4 ± 28.2 mm post-run and remained elevated at all time points with no differences between groups (p = 0.696). CCL2 concentrations increased from 116 ± 31 pg mL(-1) at baseline to 293 ± 109 pg mL(-1) at 6 h post-run (control) and from 100 ± 27 pg mL(-1) at baseline to 208 ± 71 pg mL(-1) at 6 h post-run (cryotherapy). The difference between groups was not significant (p = 0.116), but there was a trend for lower CCL2 in the cryotherapy group at 6 h (p = 0.102), though this measure was highly variable. In conclusion, 20 min of cryotherapy was ineffective in attenuating the strength decrement and soreness seen after muscle-damaging exercise, but may have mitigated the rise in plasma CCL2 concentration. These results do not support the use of cryotherapy during recovery.

Localised application of vibration improves passive knee extension in women with apparent reduced hamstring extensibility: a randomised trial

QUESTION

Does the localised application of vibration over the hamstrings improve hamstring extensibility?

DESIGN

Randomised controlled trial with concealed allocation, intention-to-treat analysis, and assessor blinding.

PARTICIPANTS

30 non-athletic females (aged 18-22 yrs) with limited hamstring extensibility bilaterally.

INTERVENTION

The experimental group received 3 sessions of localised application of vibration per week for 8 weeks. At each session, 3 sets of vibration were applied over the left and right hamstring muscles. The control group continued their usual daily activities. Both groups were asked to perform no specific exercises during the 8-week intervention period.

OUTCOME MEASURES

Hamstring muscle extensibility was measured bilaterally at baseline and at the end of the 8-week intervention period by measuring passive knee extension in supine with 90 deg of hip flexion.

RESULTS

At baseline, the mean lack of knee extension was 27 deg (SD 9) in the experimental group and 24 deg (SD 8) in the control group. At 8 weeks, this had changed to 13 deg (SD 5) in the experimental group and 23 deg (SD 9) in the control group. This was a significant treatment effect: mean between-group difference of 13 deg (95% CI 11 to 16).

CONCLUSION

An 8-week regimen of localised application of vibration over the hamstring muscles significantly reduces knee extension lack in women with reduced range on the passive knee extension test.

Efeito dos exercícios de fortalecimento e alongamento sobre a rigidez tecidual passiva

INTRODUÇÃO: Níveis excessivos ou reduzidos de rigidez passiva dos músculos, tendões, ligamentos e fáscias podem estar relacionados à ocorrência de disfunções de movimento e ao desenvolvimento de lesões musculoesqueléticas. O tratamento dessas condições comumente envolve a aplicação de técnicas voltadas para alterar a rigidez, tais como fortalecimento ou alongamento. OBJETIVO: Realizar uma revisão crítica da literatura para investigar os efeitos de exercícios de fortalecimento e alongamento sobre a rigidez tecidual passiva. MATERIAIS E MÉTODOS: Foi realizada consulta aos bancos de dados Medline, Scielo, Lilacs e PEDro. Foram incluídos estudos experimentais realizados em animais ou humanos, sem limite de data. RESULTADOS: Foram selecionados 20 estudos que investigaram o efeito do fortalecimento sobre a rigidez passiva e 13 que pesquisaram o efeito de programas de alongamento sobre a rigidez passiva. CONCLUSÃO: Os estudos sugerem que exercícios de fortalecimento de alta intensidade são capazes de aumentar os níveis de rigidez tecidual tanto em animais quanto em humanos. O aumento da área de secção transversa e modificações na composição dos tecidos são alguns dos mecanismos responsáveis por esse aumento. Em relação ao fortalecimento muscular em posição alongada e ao fortalecimento excêntrico em toda amplitude com carga moderada, os resultados são insuficientes para afirmar sobre o real efeito dessas técnicas em reduzir os níveis de rigidez. Por fim, programas de alongamento estático ou do tipo contrai-relaxa parecem reduzir a rigidez tecidual quando realizados por meio de protocolos de longa duração e/ou alta frequência.

Comparison of active stretching technique in males with normal and limited hamstring flexibility

OBJECTIVE

(1) to analyse the accumulative effects of a 12-week active stretching program on hip flexion passive range of motion (HF-PROM), and (2) to compare whether participants with different PROM baseline scores (normal and limited hamstring flexibility) respond in the same way to stretching.

DESIGN

Repeated measures design.

SETTING

Controlled laboratory environment.

PARTICIPANTS

138 males were categorized according to hamstring flexibility in the unilateral passive straight-leg raise test (PSLR) and assigned to one of two groups: normal hamstring flexibility (≥80°) or limited hamstring flexibility (<80°). In each group, participants were randomly distributed into one of two treatment subgroups: (a) control or (b) active stretching. The active stretching subgroups performed 12 weeks of flexibility training, the control subgroups did not stretch.

MAIN OUTCOME MEASURES

HF-PROM was determined through the PSLR test.

RESULTS

Both stretching subgroups significantly improved (p < 0.01) their HF-PROM from baseline. The control subgroups did not.

CONCLUSIONS

12 weeks of an active stretching program performed 3 days per week with a daily stretch dose of 180 s improved HF-PROM in both populations (normal and limited hamstring flexibility). The stretching program was equally effective in terms of absolute improvement values for males with normal and limited hamstring flexibility.