Acute effect of static stretching and pilates stretching on the concentric muscle strength of the knee extensors and flexors.

INTRODUCTION: The effects of stretching exercises on muscle strength have been widely researched in the literature, however, there are no studies investigating the effects of Pilates stretching. OBJECTIVE: To compare the effects of static stretching and Pilates stretching on the concentric muscle strength of the knee extensors and flexors. METHOD: 102 trained young adults were randomized into three groups: static stretching (n = 33); Pilates stretching (n = 34); control (n = 35). Isokinetic evaluation of the knee extensor and flexor muscles was performed at 60°/s and 180°/s, pre and post acute intervention with stretching. Interventions in the static stretching and Pilates stretching groups occurred in 3 sets x 30 s for each body region considered (a-knee extensor muscles; b-knee flexor muscles). The control group did not perform any intervention. RESULTS: No difference (p > 0.05) was observed between the groups after the intervention. There was only a significant intragroup improvement for the control group on the isokinetic muscle strength of the knee flexors at 180°/s, with a moderate effect size, considering the entire sample (p = 0.040; d = 0.42) and when considering only male gender (p = 0.010; d = 0.60). CONCLUSION: Static stretching or Pilates stretching performed as a warm-up did not impair or enhance the concentric muscle strength performance of the knee extensors and flexors. In this way, both forms of stretching can be considered as preparatory exercises before muscle strength training.

Effects of stretching exercises on muscle tension, fatigue, strength, and lactic acid accumulation: A pre-experimental study among fish transport workers.

Fish transport workers in Indonesia lift loads more than the specified limits, both in weight and frequency. This could cause lactic acid accumulation, fatigue and reduced physical performance. The aim of this study was to assess the effect of stretching intervention on muscle tension, fatigue, strength, and lactic acid level in fish transport workers in Indonesia. A pre-experimental study design with one group (pre- and post-test) design was conducted among male fish transport workers at the Tawang fish auction, Weleri, Central Java, Indonesia, in June 2022 for two weeks. We created a 1.5-minute stretching exercise video based on the University of New Castle's Manual Handling guideline, involving hand, feet, and shoulder movements. Participants performed these exercises independently before and during work every two hours, guided by the video. Data on lactic acid, muscle tension, fatigue, and strength were collected before and after the 2-week intervention. Data analysis was performed using Wilcoxon and paired Student t-tests to compare the outcome between post- and pre-intervention. A total of 18 fish transport workers were included in the study. The results showed a statistically significant increase in lactic acid levels following the intervention (p=0.016). However, the increase in muscle tension was not statistically significant (p=0.292). There was a significant increase in fatigue levels after the intervention (p=0.000). This could suggest that the stretching intervention may have had an unintended effect of increasing fatigue among the participants. On the other hand, there was a statistically significant decrease in muscle strength after the intervention (p=0.003). In conclusion, this study suggests that while stretching exercises can affect lactic acid accumulation, fatigue, and muscle strength, they do not influence muscle tension. Therefore, it is advised for workers to incorporate stretching exercises into their daily routine to mitigate potential injury risks.

Effect of Static Stretching on Tendon Hysteresis and Efficiency During Repetitive Jumping.

ABSTRACT: Sasajima, S and Kubo, K. Effect of static stretching on tendon hysteresis and efficiency during repetitive jumping. J Strength Cond Res 38(6): 1041-1047, 2024-To date, no studies have experimentally shown a relationship between tendon hysteresis and exercise efficiency. However, previous studies showed that tendon hysteresis decreased immediately after static stretching. The purposes of this study were to (a) investigate the change in tendon hysteresis during the recovery period after static stretching and (b) determine whether exercise efficiency is enhanced because of the decline of tendon hysteresis after static stretching. For stretching (1 minute × 4 sets) and control conditions, tendon hysteresis was measured during ramp (i.e., lower strain rate of tendon) and ballistic (i.e., higher strain rate of tendon) contractions before, immediately, 15, 30, 45, and 60 minutes after interventions. In addition, electromyograms of the plantar flexor muscles (medial gastrocnemius [MG], lateral gastrocnemius [LG], and soleus muscles [SOL]) and oxygen consumption (V̇O 2 ) were measured during 10 minutes of submaximal repetitive jumping after both interventions. Tendon hysteresis (during ramp and ballistic contractions) reduced by static stretching persisted for up to 60 minutes (effect of time p < 0.001). During repetitive jumping, no differences in electromyograms of the plantar flexor muscles (effect of condition p = 0.786 for MG, p = 0.124 for LG, p = 0.682 for SOL) or V̇O 2 (effect of condition p = 0.534) were found between stretching and control conditions. These results suggest that the reduction in tendon hysteresis because of static stretching continues until 60 minutes after the end of stretching, and static stretching does not change the efficiency (evaluated by electromyograms of the plantar flexor muscles and V̇O 2 ) during submaximal repetitive jumping.

Effective Stretching Positions of the Piriformis Muscle Evaluated Using Shear Wave Elastography.

CONTEXT: Piriformis syndrome is often associated with muscle spasms and shortening of the piriformis muscle (PM). Physical therapy, including static stretching of the PM, is one of the treatments for this syndrome. However, the effective stretching position of the PM is unclear in vivo. This study aimed to determine the effective stretching positions of the PM using ultrasonic shear wave elastography. DESIGN: Observational study. METHODS: Twenty-one healthy young men (22.7 [2.4] y) participated in this study. The shear elastic modulus of the PM was measured at 12 stretching positions using shear wave elastography. Three of the 12 positions were tested with maximum internal rotation at 0°, 20°, or 40° hip adduction in 90° hip flexion. Nine of the 12 positions were tested with maximum external rotation at positions combined with 3 hip-flexion angles (70°, 90°, and 110°) and 3 hip-adduction angles (0°, 20°, and 40°). RESULTS: The shear elastic modulus of the PM was significantly higher in the order of 40°, 20°, and 0° of adduction and higher in external rotation than in internal rotation. The shear elastic modulus of the PM was significantly greater in combined 110° hip flexion and 40° adduction with maximum external rotation than in all other positions. CONCLUSION: This study revealed that the position in which the PM was most stretched was maximum external rotation with 110° hip flexion and 40° hip adduction.

Effects of different treatments on pain, functional disability, position sense and range of motion in elite bodybuilders with chronic low back pain.

Back pain is one of the major global challenges and is one of the most prevalent musculoskeletal disorders occurring in 80% of people at least once in their lifetime. Therefore, the need to find appropriate treatment methods for this issue is very important. The objective is to examine the short-term and acute effects of a treatment session with dry needling, massage therapy, stretching exercises and Kinesio tape on pain, functional disability, position sense and range of motion in elite bodybuilders with non-specific chronic low back pain. The sample of this quasi-experimental study consisted of 48 bodybuilders with non-specific chronic low back pain (all male, mean age = 25.96 ± 2.18 years; mean weight = 74.45 ± 4.51 kg; mean height = 173.88 ± 3.74 cm; mean BMI = 24.60 ± 0.74 kg/m2) who randomly were placed in 4 dry needling, massage therapy, stretching exercises and Kinesio tape groups. The duration of each intervention was 30 min. The dependent variables in this study included the massage range of motion, position sense tests and visual pain scale that were taken separately from each subject in pretest, posttest (acute effect) and follow-up test (72 h after posttest; short-term effect). The results of a 4 (groups) × 3 (time) the mixed ANOVAs showed that pain in the short-term phase was significantly lower in the dry needling group than in the stretching and massage groups (P < 0.05). Also in the acute effect phase, the flexion range of motion was significantly lower in the dry needling group than in the massage group (P < 0.05). Furthermore, the two groups of stretching and massage exercises showed significantly greater range of motion (P < 0.05). Other comparisons were not significant (P > 0.05). The findings of the study showed that both massage and stretching treatment have higher acute effects, while dry needling treatment was more effective in follow up. On the other hand, these findings show that these treatment methods can have immediate and lasting positive effects in improving the performance in elite bodybuilders with non-specific chronic low back pain.

Examining the Influence of Warm-Up Static and Dynamic Stretching, as well as Post-Activation Potentiation Effects, on the Acute Enhancement of Gymnastic Performance: A Systematic Review with Meta-Analysis.

The primary objective of this systematic review with meta-analysis is to methodically discern and compare the impact of diverse warm-up strategies, including both static and dynamic stretching, as well as post-activation potentiation techniques, on the immediate performance of gymnasts. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this paper evaluated studies that examined the gymnasts' performance after different warm-up strategies namely stretching (static [SS] or dynamic), vibration platforms (VP) or post-activation, in comparison to control conditions (e.g., mixed warm-up routines; no warm-up). The principal outcomes were centered on technical performance metrics (e.g., split, gymnastic jumps) and physical performance metrics (e.g., squat jump, countermovement jump, drop jump, balance, range of motion). Methodological assessments of the included studies were conducted using the Downs and Black Checklist. From the initial search across PubMed, Scopus, and the Web of Science databases, a total of 591 titles were retrieved, and 19 articles were ultimately incorporated in the analysis. The results revealed a non-significant differences (p > 0.05) between the SS condition and control conditions in squat jump performance, countermovement jump and gymnastic technical performance (e.g., split; split jump). Despite the difference in warm-up strategies and outcomes analyzed, the results suggest that there is no significant impairment of lower-limb power after SS. Additionally, technical elements dependent on flexibility appear to be enhanced by SS. Conversely, dynamic stretching and VP seem to be more effective for augmenting power-related and dynamic performance in gymnasts.

Synergistic difference in the effect of stretching on electromechanical delay components.

This study investigated the synergistic difference in the effect of stretching on electromechanical delay (EMD) and its components, using a simultaneous recording of electromyographic, mechanomyographic, and force signals. Twenty-six healthy men underwent plantar flexors passive stretching. Before and after stretching, the electrochemical and mechanical components of the EMD and the relaxation EMD (R-EMD) were calculated in gastrocnemius medialis (GM), lateralis (GL) and soleus (SOL) during a supramaximal motor point stimulation. Additionally, joint passive stiffness was assessed. At baseline, the mechanical components of EMD and R-EMD were longer in GM and GL than SOL (Cohen's d from 1.78 to 3.67). Stretching decreased joint passive stiffness [-22(8)%, d = -1.96] while overall lengthened the electrochemical and mechanical EMD. The mechanical R-EMD components were affected more in GM [21(2)%] and GL [22(2)%] than SOL [12(1)%], with d ranging from 0.63 to 1.81. Negative correlations between joint passive stiffness with EMD and R-EMD mechanical components were found before and after stretching in all muscles (r from -0.477 to -0.926; P from 0.007 to <0.001). These results suggest that stretching plantar flexors affected GM and GL more than SOL. Future research should calculate EMD and R-EMD to further investigate the mechanical adaptations induced by passive stretching in synergistic muscles.

Combined effect of myofascial release and passive stretching on plantar pressure in individual with hamstring tightness- an experimental study.

INTRODUCTION: The lower kinetic chain is known to be affected by hamstring tightness which causes biomechanical alterations. As per the literature, short hamstring might cause prolonged forefoot loading, which can cause higher repeated stress on the plantar fascia. There is evidence supporting the use of various stretching and myofascial release techniques for hamstring tightness, further research is needed to investigate their impact on plantar pressure. Hence the study aims to determine combined effect of myofascial release and passive stretching on plantar pressure in individual with hamstring tightness. METHODS: This was an experimental pre-post study design with 67 randomised screenings from asymptomatic health care science students aged 18 to 25. From this scientific survey, a sample size of 47 students having HMS tightness based on the popliteal angle were recruited using a universal goniometer. An intervention was proposed that included MFR and passive stretching in 3 sessions on alternate days. Plantar pressure of these individuals was noted by using the "Harris and Beath foot printing mat" before and after the intervention. RESULT: Significant pressure changes were observed after intervention: great toe of right side (p = 0.001), toes 2 to 5 of right side (p = 0.010) and left side (p = 0.008), first metatarsal of left side (p = 0.010), lateral forefoot of right side (p = 0.019) and left (p = 0.018), medial heel (p = 0.044), and lateral heel of right side (p = 0.025). These values substantiate the enhancement in plantar pressure. CONCLUSION: The combined effect of Myofascial release and passive stretching in an individual with hamstring tightness resulted in a significant increase in popliteal angle and plantar pressure.

Combined Effects of Static and Dynamic Stretching on the Muscle-Tendon Unit Stiffness and Strength of the Hamstrings.

ABSTRACT: Takeuchi, K, Nakamura, M, Matsuo, S, Samukawa, M, Yamaguchi, T, and Mizuno, T. Combined effects of static and dynamic stretching on the muscle-tendon unit stiffness and strength of the hamstrings. J Strength Cond Res 38(4): 681-686, 2024-Combined static and dynamic stretching for 30 seconds is frequently used as a part of a warm-up program. However, a stretching method that can both decrease muscle-tendon unit (MTU) stiffness and increase muscle strength has not been developed. The purpose of this study was to examine the combined effects of 30 seconds of static stretching at different intensities (normal-intensity static stretching [NS] and high-intensity static [HS]) and dynamic stretching at different speeds (low-speed dynamic [LD] and high-speed dynamic stretching [HD]) on the MTU stiffness and muscle strength of the hamstrings. Thirteen healthy subjects (9 men and 4 women, 20.9 ± 0.8 years, 169.3 ± 7.2 cm, 61.1 ± 8.2 kg) performed 4 types of interventions (HS-HD, HS-LD, NS-HD, and NS-LD). Range of motion (ROM), passive torque, MTU stiffness, and muscle strength were measured before and immediately after interventions by using an isokinetic dynamometer machine. In all interventions, the ROM and passive torque significantly increased (p < 0.01). Muscle-tendon unit stiffness significantly decreased in HS-HD and HS-LD (both p < 0.01), but there was no significant change in NS-HD (p = 0.30) or NS-LD (p = 0.42). Muscle strength significantly increased after HS-HD (p = 0.02) and NS-LD (p = 0.03), but there was no significant change in HS-LD (p = 0.23) or NS-LD (p = 0.26). The results indicated that using a combination of 30 seconds of high-intensity static stretching and high-speed dynamic stretching can be beneficial for the MTU stiffness and muscle strength of the hamstrings.

The Training and Tapering Practices of Highland Games Heavy Event Athletes.

ABSTRACT: Winwood, PW, Keogh, JW, Travis, SK, Grieve, I, and Pritchard, HJ. The training and tapering practices of Highland Games heavy event athletes. J Strength Cond Res 38(3): e116-e124, 2024-This study provides the first empirical evidence of how Highland Games heavy event athletes train and taper for Highland Games competitions. Athletes (n = 169) (mean ± SD: age 40.8 ± 10.7 years, height 181.2 ± 9.5 cm, weight 107.2 ± 23.0 kg, 18.8 ± 10.3 years of general resistance training, and 8.1 ± 6.9 years of competitive Highland Games experience) completed a self-reported 4-page online survey on training and tapering practices. Analysis by sex (male and female) and competitive standard (local or regional, national, and international) was conducted. Seventy-eight percent (n = 132) of athletes reported that they used a taper. Athletes stated that their taper length was 5.2 ± 3.5 days, with the step (36%) and linear tapers (33%) being the most performed. Athletes reported that their highest training volume and intensity were 5.5 and 3.8 weeks out (respectively) from competition, and all training ceased 2.4 ± 1.4 days before competition. Training volume decreased during the taper by 34%. Athletes typically stated that, tapering was performed to achieve recovery, peak performance, and injury prevention; training intensity, frequency, and duration stayed the same or decreased; game-specific training increased with reductions in traditional exercises; the caber toss, weight for height, and heavy weight throw were performed further out from competition than other events; muscular power and strength were the most common types of training performed; static stretching, foam rolling, and massage were strategies used in the taper; and poor tapering occurred because of life/work circumstances, lack of sleep/rest, or training too heavy/hard. These results may aid Highland Games athletes to optimize training and tapering variables leading to improved performances.

Warm-up is an efficient strategy to prevent diurnal variation of short-term maximal performance in young basketball players.

The objectives of this study were to investigate: 1) whether there were morning-to-evening differences in short-term maximal performance and 2) the impact of prolonged and specific warm-up on short-term maximal performance diurnal variations in young basketball players. Fifteen basketball players of both sexes (Male = 8; Female = 7; age: 14.4 ± 0.46 yr; weight: 64.7 ± 7.1 kg; height: 175.2 ± 6.6 cm; BMI: 21.1 ± 1.9 kg/m2) completed the following short-term maximal performance tests: CMJ with and without arm swing, Lane Agility Drill, Zig-Zag agility test with and without the ball, Sprint 20 m with and without the ball with the passage at 5 and 10 m. All tests were performed after the 15-min standard warm-up procedure (with static stretching) and/or 25-min specific warm-up (with prolonged running and dynamic stretching) in the morning and evening. Vertical jumping tests and all change-of-direction speed tests (with and without a ball) with superior responses were achieved in the evening after standard warm-up among all participants (p < 0.05). In contrast, superior short-term maximal performance was observed in the morning after prolonged and specific warm-up protocol (p < 0.05). It was concluded that specific and prolonged warm-up protocols are suitable strategy to prevent diurnal variation in short-term maximal performance in young basketball players.

Effects of functional correction training on movement patterns and physical fitness in male college students.

The objective of this study is to investigate the effects of functional corrective training and static stretching on the quality of movement patterns and physical fitness in college students. The study was conducted with 30 male college students from a university in Guangzhou, China. The participants were randomly assigned to either the functional corrective training group (FCT, n = 15, age = 20.93 ± 0.85, BMI = 22.07 ± 2.33) or the static stretching group (SS, n = 13, age = 20.85 ± 0.86, BMI = 21.98 ± 1.80). Two participants from the SS group dropped out due to personal reasons, leaving 13 subjects in that group. Both groups underwent a 6-week training intervention, with sessions held twice a week. The FCT group participated in flexibility training, and/or static motor control training, and/or dynamic motor control training for 10-15 min. The SS group performed static stretching exercises targeting five specific muscles, with 30 s per side and two sets. The Functional Movement Screen (FMS), body composition, sit-and-reach, standing long jump, and pull-ups were assessed before and after the intervention. Differences in FMS outcomes were analyzed using two samples of the Mann-Whitney U test. Physical fitness outcomes were analyzed using a repeated measures analysis of variance (ANOVA) with a 2 (group) × 2 (time) design. After 6 weeks of intervention, the FCT group showed statistically significant improvements in the hurdle step (Z = -2.449, p = 0.014), inline lunge (Z = -2.000, p = 0.046), rotary stability (Z = -2.309, p = 0.021), and composite scores (Z = -3.316, p = 0.001). Comparisons between groups indicated that BMI (FCT, ES = 0.04; SS, ES = -0.11), 30-m sprint (FCT, ES = 0.12; SS, ES = 0.28), body fat percentage (BF%) (FCT, ES = -0.25; SS, ES = -0.07), and sit-and-reach (FCT, ES = 0.17; SS, ES = 0.06) were not statistically significant in both the pre- and post-tests. The effect sizes of all physical fitness indicators were greater in the FCT group than in the SS group. The FCT, consisting of two sessions per week for 6 weeks, has been proven to be effective in improving the quality of movement patterns by improved stability and advanced movements. However, the improvements in physical fitness did not reach statistical significance. FMS and FCT are generally affordable and accessible for college students. College students have the opportunity to employ the FMS tool to assess potential injury risks and address them, thereby reducing the risk of injuries.

The impact of whole-body vibration training and proprioceptive neuromuscular facilitation on biomechanical characteristics of lower extremity during cutting movement in individuals with functional ankle instability: A parallel-group study.

BACKGROUND: We compared the effects of whole-body vibration training and proprioceptive neuromuscular facilitation on the biomechanical characteristics of the lower limbs in functional ankle instability patients during cutting movement to ascertain the superior rehabilitation method. METHODS: Twenty-two male College students with unilateral functional ankle instability volunteered for this study and were randomly divided into whole-body vibration training group and proprioceptive neuromuscular facilitation group. Kinematics data and ground reaction forces were collected using infrared motion capture system and 3-D force plates synchronously during cutting. Repeated measures two-way ANOVA was performed to analyze the data. FINDINGS: Both training methods reduced the maximum hip abduction angle (p = 0.010, effect size: proprioceptive neuromuscular facilitation = 0.69; whole-body vibration training = 0.20), maximum knee flexion angle (p = 0.008, effect size: proprioceptive neuromuscular facilitation = 0.39, whole-body vibration training = 1.26) and angular velocity (p = 0.014, effect size: proprioceptive neuromuscular facilitation = 0.62, whole-body vibration training = 0.55), maximum ankle inversion angular velocity (p = 0.020, effect size: proprioceptive neuromuscular facilitation = 0.52, whole-body vibration training = 0.81), and knee flexion angle at the time of maximum vertical ground reaction forces (p = 0.018, effect size: proprioceptive neuromuscular facilitation = 0.27, whole-body vibration training = 0.76), and increased the maximum ankle dorsiflexion moment (p = 0.049, effect size: proprioceptive neuromuscular facilitation = -0.52, whole-body vibration training = -0.22). Whole-body vibration training reduced the maximum ground reaction forces value in the mediolateral directions (p = 0.010, effect size = 0.82) during cutting movement. INTERPRETATION: These findings suggested that the two types of training might increase neuromuscular conduction function around the ankle. After these two types of training, functional ankle instability patients showed a similar risk of injury to the lateral ankle ligaments during cutting.

The acute effect of passively assisted trunk stretching on central arterial stiffness and blood pressure in middle-aged to older adults.

PURPOSE: We examined the effects of acute trunk stretching on central arterial stiffness and central and peripheral blood pressure in middle-aged to older adults. METHODS: Twenty-eight middle-aged to older adults (14M/14F, 72 ± 7 years, 28.5 ± 5.3 kg/m2) completed this randomized, controlled, crossover design trial. We measured carotid-femoral pulse wave velocity (cf-PWV) and central and peripheral blood pressures (BP) before and after a single bout of passively assisted trunk stretching (i.e., five rounds of six 30-s stretches) and a time-matched seated control visit (i.e., 30-min). Changes (Δ; post - pre) in cf-PWV and central and peripheral BP were compared between visits and sexes using separate linear mixed-effects models controlling for baseline values. RESULTS: Compared with seated control, central (systolic: - 3 ± 7 mmHg; diastolic: - 2 ± 5 mmHg) and peripheral (systolic: - 2 ± 8 mmHg; diastolic: - 1 ± 4 mmHg) BP were reduced following acute trunk stretching (ps ≤ 0.001). Between-visit differences for ∆cf-PWV (stretch: 0.09 ± 0.61 m/s; control: 0.37 ± 0.68 m/s, p = 0.038) were abolished when controlling for change in mean arterial pressure (∆MAP) (p = 0.687). The main effects of sex were detected for changes in systolic BPs (ps ≤ 0.029); more males (n = 13) saw BP reductions than females (n = 7). CONCLUSION: These findings demonstrate the superiority of acute trunk stretching over passive sitting of equated duration for BP in middle-aged to older adults, with an appreciable effect in males compared to females.

Influence of 8-weeks of supervised static stretching or resistance training of pectoral major muscles on maximal strength, muscle thickness and range of motion.

OBJECTIVES: Current research suggests static stretch-induced maximal strength increases and muscle hypertrophy with potential to substitute resistance-training routines. However, most studies investigated the plantar flexors. This study explored the effects of a static stretching program on maximal strength, hypertrophy and flexibility of the pectoralis major and compared the effects with those of traditional resistance training. METHODS: Eighty-one (81) active participants were allocated to either a static stretching, strength-training or control group. Pectoralis stretching was applied 15 min/day, 4 days per week for 8 weeks, while resistance training trained 3 days per week, 5 × 12 repetitions. RESULTS: There was an increase in all parameters (strength: p < 0.001, ƞ2 = 0.313, muscle thickness: p < 0.001, ƞ2 = 0.157-0.264, flexibility: p < 0.001, ƞ2 = 0.316) and a time*group interaction (strength: p = 0.001, ƞ2 = 0.154, muscle thickness: p = 0.008-0.001, ƞ2 = 0.117-0.173, flexibility: p < 0.001, ƞ2 = 0.267). Post-hoc testing showed no difference between both intervention groups regarding maximal strength and muscle thickness (p = 0.905-0.983, d = 0.036-0.087), while flexibility increased in the stretching group (p = 0.001, d = 0.789). CONCLUSION: Stretching showed increases in maximal strength and hypertrophy, which were comparable with commonly used resistance training. Based on current literature, the influence of mechanical tension as the underlying mechanism is discussed. Furthermore, as equipment and comparatively long stretching durations are requested to induce meaningful strength increases in recreationally active participants, practical application seems limited to special circumstances.

Effects of Static Hamstring Stretching on Maximal Sprint Speed and Relationship With Nordic Hamstring Strength.

This study aimed to determine the acute effects of static stretching of the hamstrings on maximal sprint speed and its spatiotemporal variables and lower-limb kinematics during the late swing phase, as well as the relationship with Nordic hamstring strength. The study had a within-participant experimental design. Sixteen healthy male college sprinters were asked to sprint 80 m without static stretching and with static stretching of the hamstrings for 4 × 30 s per leg before the sprint; both conditions were counterbalanced. The knee flexion peak torque was measured using the Nordic hamstring. The differences between no static stretching and static stretching as well as their relationship with Nordic hamstring strength were investigated. The results showed that the touchdown distance (p = .036) significantly increased following static stretching. Although not significant, maximal sprint speed decreased (p = .086), and the theoretical hamstring length (difference between knee angle and hip angle) at ipsilateral touchdown was greater (p = .069) following static stretching. In addition, a lower peak torque of the Nordic hamstring resulted in a more significant decrease in maximal sprint speed following static stretching. Therefore, static stretching of the hamstring just before sprinting may increase the theoretical hamstring length during the late swing phase at maximal sprint speed and induce kinematics that increases the hamstring strain injury risk. Moreover, it is suggested that improving the Nordic hamstring strength may help minimize the negative effects of static stretching on the hamstrings.

Chronic Effects of Inter-Set Static Stretching on Morphofunctional Outcomes in Recreationally Resistance-Trained Male and Female.

Purpose: The purpose of this study was to compare the effects of resistance training (RT) with inter-set static stretching (IS) versus traditional RT (TRT) on morphofunctional outcomes in recreationally resistance-trained male and female. Methods: Twenty-two recreationally-trained subjects were allocated to IS group (n = 12) or TRT (n = 10) and completed eight weeks of RT. The only difference between the groups was that IS group included static stretching between sets, while the TRT rested between the sets. Ultrasound images, dynamic and isometric strength tests for the elbow flexors and elbow extensors were evaluated pre- and post-intervention period. Results: Total training volume (TTV) was greater in TRT than IS (p = .031). TRT and IS caused similar increases in maximal dynamic and isometric strength. Fascicle length of the brachialis increased following TRT (p = .033); muscle thickness and the pennation angle of the distal portion of the triceps brachii increased following IS (p = .035 and p = .007, respectively). There were no significant changes in thickness and architecture for biceps brachii in either group. There were no significant differences between groups for any muscle strength and morphology outcome. Conclusion: IS negatively affects TTV but does not affect muscle strength and architecture of recreationally resistance-trained male and female.

Comparative Effectiveness of Active Recovery and Static Stretching During Post-Exercise Recovery in Elite Youth Basketball.

Purpose: To compare the effectiveness of active recovery (AR) versus static stretching (SS) during post-exercise recovery in basketball. Methods: Using a counterbalanced crossover design, 17 elite youth male players completed two 90-min training sessions, followed by either AR or SS. Differences in jump height (CMJ), heart rate variability (Ln-rMSSD), muscle soreness (VAS), perceived recovery (TQR) and hormonal biomarkers (cortisol, testosterone, testosterone:cortisol ratio) between interventions were assessed at pre-session, post-session (except hormonal biomarkers), post-recovery and 24 h post-session. Differences in Ln-rMSSD were additionally assessed upon awakening on training day, and the following morning. Results: No significant differences were found between interventions at corresponding time points (p > .05). However, the within-intervention time course of recovery differed, as CMJ values were lower at post-recovery, compared with all other time points, in SS only (p < .05, effect size [ES] moderate-to-very large). Additionally, Ln-rMSSD values failed to return to baseline at post-recovery in AR only (p < .05, ES large-to-very large). Similarly, TQR scores were impaired at post-session and post-recovery in AR only (p < .05, ES moderate-to-large). No differences were reported for the remaining variables (p > .05). Conclusion: Differences between AR and SS were probably due to short-term phenomena, indicating that neither strategy was likely superior for improving recovery in the longer term. Overall, neither strategy seemed to significantly improve post-exercise recovery.

Does Prophylactic Stretching Reduce the Occurrence of Exercise-Associated Muscle Cramping? A Critically Appraised Topic.

CLINICAL SCENARIO: Exercise-associated muscle cramps (EAMC) are sudden, painful, and involuntary contractions of skeletal muscles during or after physical activity. The best treatment for EAMC is gentle static stretching until abatement. Stretching is theorized to relieve EAMC by normalizing alpha motor neuron control, specifically by increasing Golgi tendon organ activity, and physically separating contractile proteins. However, it is unclear if stretching or flexibility training prevents EAMC via the same mechanisms. Despite this, many clinicians believe prophylactic stretching prevents EAMC occurrence. CLINICAL QUESTION: Do athletes who experience EAMC during athletic activities perform less prophylactic stretching or flexibility training than athletes who do not develop EAMC during competitions? SUMMARY OF KEY FINDINGS: In 3 cohort studies and 1 case-control study, greater preevent muscle flexibility, stretching, or flexibility training (ie, duration, frequency) was not predictive of who developed EAMC during competition. In one study, athletes who developed EAMC actually stretched more often and 9 times longer (9.8 [23.8] min/wk) than noncrampers (1.1 [2.5] min/wk). CLINICAL BOTTOM LINE: There is minimal evidence that the frequency or duration of prophylactic stretching or flexibility training predicts which athletes developed EAMC during competition. To more effectively prevent EAMC, clinicians should identify athletes' unique intrinsic and extrinsic risk factors and target those risk factors with interventions. STRENGTH OF RECOMMENDATION: Minimal evidence from 3 prospective cohort studies and 1 case-control study (mostly level 3 studies) that suggests prophylactic stretching or flexibility training can predict which athletes develop EAMC during athletic competitions.