Effects of ankle position during static stretching for the hamstrings on the decrease in passive stiffness

The effect of Liquid ice after high-intensity exercise on muscle function compared to Block ice

Cryotherapy is used to recover muscle damage after exercise and to treat acute sports injuries. Liquid ice (LI) can keep cold for a long time, and is assumed more effective than block ice (BI). From this, the aim of this study was to investigate the effects of LI on the change of passive stiffness (PS) as muscle function and to validate the effectiveness of LI compared to BI. We performed the experiment as part of a case series of verification of the effects of cryotherapy. 22 healthy men (target area: right leg) were randomized to two groups: LI group and BI group. PS was measured three times during experiment protocol, pre: before exercise; post; after treating each cryotherapy after exercise; 48h: 48 hours after pre. Statistical analysis compared the PS, the amount of change in PS, and the rate of change in PS between the two groups. The rate of change between pre and 48h in LI was significantly lower compared to that in BI (p = 0.03). There was no significant difference regarding other results between groups. It revealed that the difference of effect between LI and BI for PS of muscles after high-intensity exercises. These results could be helpful for the choice of intervention for reducing muscle stiffness after exercise and at sports field.

The effect of static stretching on key hits and subjective fatigue in eSports

[Purpose] To explore the effects of static stretching for 20 s on key hits and subjective fatigue in an eSports-like setting. [Participants and Methods] The participants comprised of 15 healthy males who were instructed to hit a particular key on a computer keyboard using the left ring finger to achieve the maximum number of hits possible over a period of 30 s. Subjective fatigue of the forearm was assessed using a visual analog scale (VAS) before the experiment and after each trial. Trials 1, 2, and 3 were conducted in succession, with an inter-trial interval of 60 s to ensure a loaded state. Static stretching for 20 s preceded Trial 4. [Results] Over the first three trials, the number of key hits in the first 10 s gradually decreased, while the feeling of subjective fatigue gradually increased. After stretching, the number of key hits in the first 10 s of Trial 4 was similar to that observed in Trial 1, and there was no increase in subjective fatigue. [Conclusion] Static stretching for 20 s restored the number of key hits for 10 s after stretching to that before the load application and suppressed the increase in subjective fatigue.

A Survey on Stretching Practices in Women and Men from Various Sports or Physical Activity Programs

Recommendations for prescribing stretching exercises are regularly updated. It appears that coaches progressively follow the published guidelines, but the real stretching practices of athletes are unknown. The present study aimed to investigate stretching practices in individuals from various sports or physical activity programs. A survey was completed online to determine some general aspects of stretching practices. The survey consisted of 32 multiple-choice or open-ended questions to illustrate the general practices of stretching, experiences and reasons for stretching. In total, 3546 questionnaires were analyzed (47.3% women and 52.7% men). Respondents practiced at the national/international level (25.2%), regional level (29.8%), or recreationally (44.9%). Most respondents (89.3%) used stretching for recovery (74.9%) or gains of flexibility (57.2%). Stretching was generally performed after training (72.4%). The respondents also indicated they performed stretching as a pre-exercise routine (for warm-up: 49.9%). Static stretching was primarily used (88.2%) but when applied for warm-up reasons, respondents mostly indicated performing dynamic stretching (86.2%). Only 37.1% of the respondents indicated being supervised. Finally, some gender and practice level differences were noticed. The present survey revealed that the stretching practices were only partly in agreement with recent evidence-based recommendations. The present survey also pointed out the need to improve the supervision of stretching exercises.

Acute and Prolonged Effects of Stretching on Shear Modulus of the Pectoralis Minor Muscle

Increased muscle stiffness of the pectoralis minor (PMi) could deteriorate shoulder function. Stretching is useful for maintaining and improving muscle stiffness in rehabilitation and sport practice. However, the acute and prolonged effect of stretching on the PMi muscle stiffness is unclear due to limited methodology for assessing individual muscle stiffness. Using shear wave elastography, we explored the responses of shear modulus to stretching in the PMi over time. The first experiment (n = 20) aimed to clarify the acute change in the shear modulus during stretching. The shear modulus was measured at intervals of 30 s × 10 sets. The second experiment (n = 16) aimed to observe and compare the prolonged effect of different durations of stretching on the shear modulus. Short and long stretching duration groups underwent 30s × 1 set and 30s × 10 sets, respectively. The assessments of shear modulus were conducted before, immediately after, and at 5, 10, and 15 min post-stretching. In experiment I, the shear modulus decreased immediately after a bout (30 s) of stretching (p < 0.001, change: -2.3 kPa, effect size: r = 0.72) and further decreased after 3 repetitions (i.e., 90 s) of stretching (p = 0.03, change: -1.0 kPa, effect size: r = 0.53). In experiment II, the change in the shear modulus after stretching was greater in the long duration group than in the short duration group (p = 0.013, group mean difference: -2.5 kPa, partial η ² = 0.36). The shear modulus of PMi decreased immediately after stretching, and stretching for a long duration was promising to maintain the decreased shear modulus. The acute and prolonged effects on the PMi shear modulus provide information relevant to minimum and persistent stretching time in rehabilitation and sport practice.

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.