The acute benefits and risks of passive stretching to the point of pain

The effects of 6-week home-based static stretching, dynamic stretching, or eccentric exercise interventions on muscle-tendon properties and functional performance in older women

Background

Joint inflexibility is acknowledged as a significant contributor to functional limitations in the older adult, with lengthening-type exercises identified as a potential remedial approach. Nevertheless, the responses to eccentric exercise in female older adults have not been extensively studied especially in home-based environment. Here, we aimed to assess the effectiveness of home-based static stretching (ST), dynamic closed-chain stretching (DCS), or eccentric exercise (ECC) interventions on flexibility, musculotendinous architecture, and functional ability in healthy older women.

Methods

We randomly assigned 51 healthy older women (age 65.9 ± 3.4 years) to one of three interventional exercise groups: DCS (N = 17), ECC (N = 17), or ST (N = 17). The training was performed 3 times a week for 6 weeks. The participants' musculotendinous stiffness, fascicle length, eccentric strength, and functional capacities were measured before the intervention, after 6 weeks of exercise, and at a 1-month follow-up.

Results

The results showed that all three interventions improved hamstring flexibility and passive ankle dorsiflexion (p < 0.001), with increased biceps femoris and medial gastrocnemius fascicle length (p < 0.01). However, there was no significant change in musculotendinous stiffness. The ECC intervention produced a greater improvement in knee flexor and calf eccentric peak torque (p < 0.05), and gait speed (p = 0.024) than the other two interventions. The changes in flexibility and knee flexor strength remained for up to 4 weeks after detraining.

Conclusion

In conclusion, the present study suggests that home-based ECC may be more beneficial in enhancing physical capacities in older women compared with either DCS or SS interventions.

The Effects of Static Stretching Intensity on Range of Motion and Strength: A Systematic Review

The aim of this study was to systematically review the evidence on the outcomes of using different intensities of static stretching on range of motion (ROM) and strength. PubMed, Web of Science and Cochrane controlled trials databases were searched between October 2021 and February 2022 for studies that examined the effects of different static stretching intensities on range of motion and strength. Out of 6285 identified records, 18 studies were included in the review. Sixteen studies examined outcomes on ROM and four on strength (two studies included outcomes on both ROM and strength). All studies demonstrated that static stretching increased ROM; however, eight studies demonstrated that higher static stretching intensities led to larger increases in ROM. Two of the four studies demonstrated that strength decreased more following higher intensity stretching versus lower intensity stretching. It appears that higher intensity static stretching above the point of discomfort and pain may lead to greater increases in ROM, but further research is needed to confirm this. It is unclear if high-intensity static stretching leads to a larger acute decrease in strength than lower intensity static stretching.

Acute Effects of Different Intensity and Duration of Static Stretching on the Muscle-Tendon Unit Stiffness of the Hamstrings

The effects of static stretching are influenced by prescribed and applied loads of stretching. The prescribed load is calculated from the stretching duration and intensity, whereas the applied load is assessed from the force of static stretching exerted on the targeted muscle. No previous study has investigated the prescribed and applied loads of static stretching on the muscle-tendon unit stiffness simultaneously. Therefore, the purpose of the present study was to examine the acute effects of the prescribed and applied load of static stretching on the change in the muscle-tendon unit stiffness of the hamstrings by using different intensities and durations of static stretching. Twenty-three participants underwent static stretching at the intensity of high (50 seconds, 3 sets), moderate (60 seconds, 3 sets), and low (75 seconds, 3 sets), in random order. The parameters were the range of motion, passive torque, and muscle-tendon unit stiffness. These parameters were measured before stretching, between sets, and immediately after stretching by using a dynamometer machine. The static stretching load was calculated from the passive torque during static stretching. The muscle-tendon unit stiffness decreased in high- and moderate-intensity after 50 (p < 0.01, d = -0.73) and 180 seconds (p < 0.01, d = -1.10) of stretching respectively, but there was no change in low-intensity stretching for 225 seconds (p = 0.48, d = -0.18). There were significant correlations between the static stretching load and relative change in the muscle-tendon unit stiffness in moderate- (r = -0.64, p < 0.01) and low-intensity (r = -0.54, p < 0.01), but not in high-intensity (r = -0.16, p = 0.18). High-intensity static stretching was effective for a decrease in the muscle-tendon unit stiffness even when the prescribed load of static stretching was unified. The applied load of static stretching was an important factor in decreasing the muscle-tendon unit stiffness in low- and moderate-intensity static stretching, but not in high-intensity stretching.

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.

Time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching

Objectives

The purpose of this study was to examine the time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching.

Methods

Fourteen healthy men (20.9 ± 0.7 years, 169.1 ± 7.5cm, 61.6 ± 6.5kg) received static stretching for 60 seconds at two different intensities based on the point of discomfort (100%POD and 120%POD) of each participant, in random order. To evaluate the time course of changes in the flexibility of the hamstrings, the knee extension range of motion (ROM), passive torque at end ROM, and muscle-tendon unit stiffness were measured pre-stretching, post-stretching, and at both 10 and 20 minutes after static stretching.

Results

For both intensities, ROM and passive torque at pre-stretching were significantly smaller than those at post-stretching (p < 0.01 in both intensities), 10 minutes (p < 0.01 in both intensities), and 20 minutes (p < 0.01 in both intensities). The muscle-tendon unit stiffness at pre-stretching was significantly higher than that at post-stretching (p < 0.01), 10 minutes (p < 0.01), and 20 minutes (p < 0.01) only in the 120%POD, but it showed no change in the 100%POD.

Conclusion

The results showed that ROM and passive torque increased in both intensities, and the effects continued for at least 20 minutes after stretching regardless of stretching intensity. However, the muscle-tendon unit stiffness of the hamstrings decreased only after static stretching at the intensity of 120%POD, and the effects continued for at least 20 minutes after stretching.

Effects of Warm-up on Hamstring Stiffness, Stress-Relaxation, Flexibility and Knee Proprioception in Young Soccer Players

CONTEXT

Nerves or fascia may limit motion in young soccer players, thereby contributing to frequent hamstring injuries. Nerve gliding exercises and self-myofascial release techniques may enhance the range of motion.

OBJECTIVE

The aim of this study was to compare the acute effect of foam rolling (FR) and neurodynamic nerve gliding (NDNG) on hamstring flexibility, passive stiffness, viscoelasticity and proprioception during the warm-up of soccer players.

DESIGN

Crossover study design.

SETTING

Research laboratory.

PARTICIPANTS

Fifteen male soccer players on the same team (age 18.0 ± 1.4 years, body mass 76.9 ± 7.8 kg, height 183 ± 6 cm).

INTERVENTION

FR and NDNG included six sets of 45 s with 15 s rest between each set. Over a two-week period subjects performed NDNG and FR on two separate occasions.

MAIN OUTCOME MEASURE(S)

Hip flexion angle (SLR), knee extension range of motion (ROM), knee joint position sense (AKJPS), hamstring passive resistance torque (PRT), stiffness (STFmax and STF80%) and viscoelasticity (stress-relaxation test (SRT)).

RESULTS

A significant interaction between time and intervention was found for knee ROM (p = 0.017), PRT (p = 0.044), and STFmax (p = 0.042). NDNG induced an increase in ROM (p = 0.011), PRT (p = 0.008), and STFmax (p = 0.030). Both NDNG and FR induced an increase in SLR (p < 0.001). No interaction or main effects was found for SRT and AKJPS.

CONCLUSION

The inclusion of NDNG in the warm-up routine increased the ROM more in comparison with FR and may be of benefit to soccer players.

Influence of Aerobic Exercise After Static Stretching on Flexibility and Strength in Plantar Flexor Muscles

Aerobic exercise could improve stretch-induced strength deficits. However, mechanisms of the improvement were unclear. The purpose of the study was to examine the effects of aerobic exercise after static stretching (SS) on flexibility and isometric strength in ankle plantar-flexor muscles. Fifteen healthy males received two interventions after SS of their ankle plantar-flexor muscles for 5 min. One was aerobic exercise for 10-min on a cycling ergometer, and the other was a 10-min rest as a control. Range of motion (ROM) of ankle dorsiflexion, passive torque at terminal ROM, muscle-tendon unit (MTU) stiffness, muscle tendon junction displacement, peak torque of ankle plantarflexion, and the amplitude of electromyography (EMG) were measured. Immediately after the SS, in both interventions, ROM, passive torque, and muscle tendon junction displacement increased significantly (p < 0.05), while MTU stiffness, peak torque, and the amplitude of EMG were significantly decreased (p < 0.05). After 10-min on a cycling ergometer, the decreased peak torque and amplitude of EMG indicated higher values than those before SS (p < 0.05), while MTU stiffness was no change. In conclusion, SS increased ROM because of the decreased MTU stiffness as well as increased tolerance for stretching. Aerobic exercise could increase the muscle strength and amplitude of EMG which decreased after static stretching.

Immediate effects of neurodynamic nerve gliding versus static stretching on hamstring neuromechanical properties

PURPOSE

We investigated the immediate effects of neurodynamic nerve gliding (ND) on hamstring flexibility, viscoelasticity, and mechanosensitivity, compared with traditional static stretching (ST).

METHODS

Twenty-two physically active men aged 21.9 ± 1.9 years were divided randomly into two equal intervention groups using ST or ND. An isokinetic dynamometer was used to measure the active knee joint position sense, perform passive knee extension, record the passive extension range of motion (ROM) and the passive-resistive torque of hamstrings. Stiffness was determined from the slope of the passive torque-angle relationship. A stress relaxation test (SRT) was performed to analyze the viscoelastic behavior of the hamstrings. The passive straight leg raise (SLR) test was used to evaluate hamstring flexibility.

RESULTS

A significant interaction was observed for ROM and passive ultimate stiffness, reflected by an increase in these indicators after ND but not after SD. SLR increased significantly in both groups. After ST, a significantly faster initial stress relaxation was observed over the first 4 s. than after ND. There was no significant change in the active knee joint position sense.

CONCLUSIONS

ND provided a slightly greater increase in hamstring extensibility and passive stiffness, possibly by decreasing nerve tension and increasing strain in connective tissues than ST. The ST mostly affected the viscoelastic behavior of the hamstrings, but neither intervention had a significant impact on proprioception.

Involuntary hamstring muscle activity reduces passive hip range of motion during the straight leg raise test: a stimulation study in healthy people

Background

Involuntary hamstring muscle activity is present in some people during the straight leg raise test, but it is not known to what extent involuntary muscle activity limits passive joint range of motion. This study aimed to determine whether small amounts of involuntary hamstring activity limit passive hip range of motion during the straight leg raise test in healthy people.

Methods

Thirty healthy subjects were recruited from The University of Sydney. As the hamstring muscles were continuously stimulated to generate 0, 2.5, 5, 7.5 and 10% of knee flexion maximal voluntary contraction force, an investigator blinded to the amount of stimulation performed a straight leg raise test by passively raising the tested leg while keeping the knee extended. The test was stopped when the knee started to flex, at which point hip range of motion was recorded.

Results

On average, passive hip range of motion decreased by 0.6° for every 1% increase in knee flexion force caused by muscle activation (95% CI 0.3 to 0.9°, p = 0.0012). Subjects were instructed to fully relax when the straight leg raise test was performed, but a small amount of involuntary muscle activity (median 2.4% of maximal activation) was present during the trial without stimulation.

Conclusions

Small amounts of involuntary hamstring muscles activity reduce passive hip range of motion during the straight leg raise test in healthy people.

Trial registration

The protocol for this study was registered with the Open Science Framework, reference: https://osf.io/fejpf/. Registered 9 March 2017.

The EJES-3D tool for personalized prescription of exercise in axial spondyloarthritis through multimedia animations: pilot study

To develop and evaluate a web application based on multimedia animations, combined with a training program, to improve the prescription of exercises in spondyloarthritis (SpA). After a review of exercises included in the main clinical trials and recommendations of international societies, a multidisciplinary team-rehabilitators, rheumatologists, physiotherapists, computer scientists and graphic designers-developed a web application for the prescription of exercises (EJES-3D). Once completed, this was presented to 12 pairs of rehabilitators-rheumatologists from the same hospital in a workshop. Knowledge about exercise was tested in rheumatologists before and 6 months after the workshop, when they also evaluated the application. The EJES-3D application includes 38 multimedia videos and allows prescribing predesigned programs or customizing them. A patient can consult the prescribed exercises at any time from a device with internet connection (mobile, tablet, or computer). The vast majority of the evaluators (89%) were satisfied or very satisfied and considered that their expectations regarding the usefulness of the web application had been met. They highlighted the ability to tailor exercises adapted to the different stages of the disease and the quality and variety of the videos. They also indicated some limitations of the application and operational problems. The EJES-3D tool was positively evaluated by experts in SpA, potentially the most demanding group of users with the most critical capacity. This allows a preliminary validation of the contents, usefulness, and ease of use. Analyzing and correcting the errors and limitations detected is allowing us to improve the EJES-3D tool.

The effects of 4 weeks stretching training to the point of pain on flexibility and muscle tendon unit properties

PURPOSE

The purpose of this study was to compare the benefits and possible problems of 4 weeks stretching when taken to the point of pain (POP) and to the point of discomfort (POD).

METHODS

Twenty-six physically active women (20 ± 1.1 years) took part in group-based stretching classes of the hamstring muscles, 4 times per week for 4 weeks, one group one stretching to POD, the other to POP. Passive stiffness, joint range of motion (ROM), maximal isometric torque and concentric knee flexion torque, were measured before training and 2 days after the last training session.

RESULTS

Hip flexion ROM increased by 14.1° (10.1°-18.1°) and 19.8° (15.1°-24.5°) and sit-and-reach by 7.6 (5.2-10.0) cm and 7.5 (5.0-10.0) cm for POD and POP, respectively (Mean and 95% CI; p < 0.001 within group; NS between groups), with no evidence of damage in either group. Despite the large increases in flexibility there were no changes in either compliance or viscoelastic properties of the muscle tendon unit (MTU).

CONCLUSION

Hamstrings stretching to POP increased flexibility and had no detrimental effects on muscle function but the benefits were no better than when stretching to POD so there is no justification for recommending painful stretching. The improvements in flexibility over 4 weeks of stretching training appear to be largely due to changes in the perception of pain rather than physical properties of the MTU although less flexible individuals benefited more from the training and increased hamstring muscle length.