Static Stretching Impairs Sprint Performance in Collegiate Track and Field Athletes

What We Do Not Know About Stretching in Healthy Athletes: A Scoping Review with Evidence Gap Map from 300 Trials

BACKGROUND

Stretching has garnered significant attention in sports sciences, resulting in numerous studies. However, there is no comprehensive overview on investigation of stretching in healthy athletes.

OBJECTIVES

To perform a systematic scoping review with an evidence gap map of stretching studies in healthy athletes, identify current gaps in the literature, and provide stakeholders with priorities for future research.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and PRISMA-ScR guidelines were followed. We included studies comprising healthy athletes exposed to acute and/or chronic stretching interventions. Six databases were searched (CINAHL, EMBASE, PubMed, Scopus, SPORTDiscus, and Web of Science) until 1 January 2023. The relevant data were narratively synthesized; quantitative data summaries were provided for key data items. An evidence gap map was developed to offer an overview of the existing research and relevant gaps.

RESULTS

Of ~ 220,000 screened records, we included 300 trials involving 7080 athletes [mostly males (~ 65% versus ~ 20% female, and ~ 15% unreported) under 36 years of age; tiers 2 and 3 of the Participant Classification Framework] across 43 sports. Sports requiring extreme range of motion (e.g., gymnastics) were underrepresented. Most trials assessed the acute effects of stretching, with chronic effects being scrutinized in less than 20% of trials. Chronic interventions averaged 7.4 ± 5.1 weeks and never exceeded 6 months. Most trials (~ 85%) implemented stretching within the warm-up, with other application timings (e.g., post-exercise) being under-researched. Most trials examined static active stretching (62.3%), followed by dynamic stretching (38.3%) and proprioceptive neuromuscular facilitation (PNF) stretching (12.0%), with scarce research on alternative methods (e.g., ballistic stretching). Comparators were mostly limited to passive controls, with ~ 25% of trials including active controls (e.g., strength training). The lower limbs were primarily targeted by interventions (~ 75%). Reporting of dose was heterogeneous in style (e.g., 10 repetitions versus 10 s for dynamic stretching) and completeness of information (i.e., with disparities in the comprehensiveness of the provided information). Most trials (~ 90%) reported performance-related outcomes (mainly strength/power and range of motion); sport-specific outcomes were collected in less than 15% of trials. Biomechanical, physiological, and neural/psychological outcomes were assessed sparsely and heterogeneously; only five trials investigated injury-related outcomes.

CONCLUSIONS

There is room for improvement, with many areas of research on stretching being underexplored and others currently too heterogeneous for reliable comparisons between studies. There is limited representation of elite-level athletes (~ 5% tier 4 and no tier 5) and underpowered sample sizes (≤ 20 participants). Research was biased toward adult male athletes of sports not requiring extreme ranges of motion, and mostly assessed the acute effects of static active stretching and dynamic stretching during the warm-up. Dose-response relationships remain largely underexplored. Outcomes were mostly limited to general performance testing. Injury prevention and other effects of stretching remain poorly investigated. These relevant research gaps should be prioritized by funding policies.

REGISTRATION

OSF project ( https://osf.io/6auyj/ ) and registration ( https://osf.io/gu8ya ).

Impact of warm-up methods on strength-speed for sprinters in athletics: a mini review

In athletics, achieving peak performance during competitions is crucial. Warm-up strategies play a crucial role in optimizing the strength-speed performance of sprinters in athletics, especially tailored to the physiological demands of speed events. The need to balance flexibility, prevent injuries, and enhance power output makes the selection of an effective warm-up protocol essential. This narrative review examines different warm-up methods used by athletes and their effects on strength-speed in sprinters in athletics. The main findings indicate that Foam Rolling (FR), Isometric Exercises and Pre-Competitive Massages have no significant effects on sprint performance. Static stretching and prolonged Pre-Competitive Massages have negative impacts on strength and power. The Vibration Platform enhances step length, step rate and running velocity, jump height and total number of jumps performed in a 30-s period in non-experienced sprinters. Eccentric Exercise increases vertical force, Post-Activation Potentiation (PAP) demonstrates a reduction in 100-meter time and short-term improvement in vertical and horizontal jumps. Blood Flow Restriction (BFR) significantly improving jump height and flight time. Various warm-up methods have been identified, some focusing on flexibility, others potentially detrimental, and some enhancing strength and power. Implementing effective warm-ups, particularly those promoting strength and power, poses a challenge for coaches seeking reliable alternatives to boost performance.

Dynamic Stretching Increases the Eccentric Rate of Force Development, but not Jump Height in Female Volleyball Players

The present study aimed to analyze the effect of static and dynamic stretching exercises on the rate of force development (RFD) during the eccentric braking phase and jump height in a countermovement jump (CMJ) in female volleyball players. Thirty female volleyball players were randomly distributed in a static stretching (n = 10; SG), a dynamic stretching, and (n = 10; DG) a control group (n = 10; CG). A force plate and a 3D analysis system were employed to detect the eccentric braking phase during the CMJ. The RFD was analyzed in RFD (RFDi) intervals and the accumulated RFD (RFDa), and normalized to body mass. The SG experienced a likely small decrease in the RFDa (mean difference −17.4 N/s/kg) and a likely small decrease in the RFDi (mean difference −19.1 N/s/kg). Contrarily, the DG showed a likely small increase in the RFDa (mean difference 31.2 N/s/kg) and a most likely small increase in the RFDi (mean difference 34.8 N/s/kg). The effect of both static and dynamic stretching on jump height was trivial. Practitioners should consider utilizing dynamic stretching exercises instead of static stretching before a competition in female volleyball players. Further research is needed in order to find complementary strategies during the warm-up that could increase jump height.

The prevalence of pre-conditioning and recovery strategies in senior elite and non-elite amateur boxing

OBJECTIVES

A variety of acute strategies around competition are used to prepare and promote physical and mental restoration in athletes. However, to date, no research exists on the prevalence of such methods in amateur boxing. Therefore, this study aimed to 1) examine the prevalence of pre-conditioning and recovery strategies in amateur boxing; 2) ascertain whether this was discriminated against at competitor level.

METHODS

This study surveyed 101 senior amateur boxers (Senior Elite SEB n = 59; Senior Development SDB n = 42), on their application and perceptions of pre-conditioning and recovery strategies.

RESULTS

The reported findings determined a significantly greater number of SEB performed resistance priming activity up to 48 hours prior to competition (11, 19% vs 2, 5%; P = 0.040), and post-activation performance enhancement (PAPE) activity in the pre-competition warm-up (18, 31% vs 1, 2%; P < 0.001), compared to SDB. Likewise, SEB reported they were also significantly more likely to utilize massage (SEB 35, 59%, SDB 11, 29%, P = 0.001) and cold-water immersion (CWI) (SEB 28, 47%, SDB 10, 29%, P = 0.016) as recovery modes, compared to their SDB counterparts.

CONCLUSIONS

This study was the first to provide data on the use of PAPE, priming and recovery methods around amateur boxing bouts. Increased access to multi-disciplinary staff could be expected in SEB, possibly explaining the greater prevalence of evidence-based methods around competition. Once athlete responsiveness to PAPEand longer-term priming methods are initially assessed, these strategies could be implemented to improve punch-specific performance, though more research is needed on their efficacy. Likewise, boxers could utilize evidence-based recovery modes where possible, with increased importance during repeat-bout scenarios, such as domestic tournaments. Coaches and practitioners may use this data to implement pre-conditioning and recovery strategies, to optimize performance and reduce the risk of injury of amateur boxers.

Time-based effects of different duration stretching on calf muscle strength

BACKGROUND: There are conflicting reports on the acute effects of stretching on muscle strength. Some studies report reduction in muscle strength however others report no change following stretching. OBJECTIVE: To assess the acute effects of static stretching (SS) of different durations on the isometric maximum voluntary contraction force (MVCF) of the calf muscle. METHODS: Pretest-posttest experimental design was used. Ten male participants (mean age 25.4 ± 2.11 years) participated in three experimental trials: SS for 2-minutes (SS2), 4-minutes (SS4), and 8-minutes (SS8). MVCF was measured before, immediately after, at 10- and 20-minutes post-stretch intervals. Each SS trial involved varied repetitions of 30-seconds stretches and 20-seconds relaxation periods. The isometric maximum voluntary contraction force (MVCF) was the outcome measure. RESULTS: SS2, SS4, and SS8 did not change the MVCF at 0-, 10- and 20-minutes post stretching intervals (p> 0.05). CONCLUSIONS: 2-, 4-, and 8-minutes intermittent SS did not change the isometric muscle strength in the Calf muscle up to 20 minutes after stretching and thus can safely be performed before those sporting events that require significant muscle strength.

Hamstring Injury Prevention Program and Recommendation for Stride Frequency during Tow-Training Optimization

(1) Background: Although innovations and improvements in towing systems have been available, tow-training method has not been considered favored in the training context. Tow-training may enable high stride frequency if hamstring injuries do not occur. The purpose of this study was to prevent hamstring injuries during supramaximal running and to optimize tow-training. (2) Methods: We investigated the relationship between the number of hamstring injuries that occurred during supramaximal running and the contents of the prevention programs that have been implemented, i.e., 4 years of the baseline programs and 12 years of the intervention. (3) Results: The incidence of hamstring injuries per 1000 sprinters was 57.5 for baseline and 6.7 for intervention. A significant difference was observed in the incidence of hamstring injury between the different combinations of prevention programs (p < 0.01). (4) Conclusions: Tow-training was optimized by (1) preventing hamstring injuries by combination of strength, agility, and flexibility training programs and (2) advising the sprinters to press the leg onto the ground as fast as possible to increase stride frequency and to prevent stride lengthening.

Estimating Postmatch Fatigue in Soccer: The Effect of Individualization of Speed Thresholds on Perceived Recovery

PURPOSE

To investigate the effectiveness of different individualization methods of speed zones during match play to estimate postmatch perceptual recovery in soccer.

METHODS

Twelve players under the age of 19 y undertook field-based assessments to determine their maximal aerobic speed (MAS) and maximal sprint speed (MSS). External load (extracted from 10-Hz GPS over 10 official matches) was measured and classified into 4 categories as follows: low-speed running, moderate-speed running, high-speed running, and sprinting. Match running distribution into different speed zones was categorized using either MAS, MSS, MAS and MSS as measures of locomotor capacities, and absolute values. Players perceived recovery status was recorded immediately postmatch (Post) and 24 (G+24H) and 48 hours (G+48H) after each game.

RESULTS

Different individualization methods resulted in distinct match outputs in each locomotor category. Perceived recovery status was lower (P < .001) at Post (3.8 [1.32], 95% confidence interval [CI], 3.6 to 4.2), G+24H (5.2 [1.48], 95% CI, 4.9 to 5.6), and G+48H (6.0 [1.22], 95% CI, 5.7 to 6.3) compared with prematch values (7.1 [1.05], 95% CI, 6.8 to 7.3). The absolute perceived recovery-status score was better associated with high-speed running using the locomotor-capacities method at Post (β = -1.7, 95% CI, -3.2 to -0.22, P = .027), G+24H (β = -2.08, 95% CI, -3.22 to -0.95, P = .001), and G+48H (β = -1.32, 95% CI, -2.2 to -0.4, P = .004) compared with other individualization methods.

CONCLUSION

The authors' results suggest that locomotor capacities may better characterize the match intensity distribution (particularly for the high-speed running and sprinting categories) and should be preferred over MAS and MSS to estimate perceived recovery.

Dynamic Balance in Athletes With Intellectual Disability: Effect of Dynamic Stretching and Plyometric Warm-Ups

CONTEXT

Athletes with intellectual disability (ID) have a high risk of injury while participating in various sports. Warm-up (WU) is the most preventive measure to reduce injuries in sports.

OBJECTIVE

To investigate the effects of dynamic stretching WU (DS-WU) and plyometric WU (PL-WU) on dynamic balance in athletes with ID.

DESIGN

Crossover study.

SETTING

Research laboratory.

PARTICIPANTS

A total of 12 athletes with ID (age 24.5 [3.22] y, height 165.7 [8.4] cm, weight 61.5 [7.1] kg, intelligence quotient 61.1 [3.5]).

MAIN OUTCOME MEASURES

Dynamic balance was assessed using the Star Excursion Balance Test (SEBT) at pre-WU, post-WU, and 15 minutes post-WU for both the DS-WU and the PL-WU. A 2-way analysis of variance (3 sessions × 2 WU methods) with repeated-measures was used in this study.

RESULTS

Following the DS-WU, participants demonstrated significant improvements in the SEBT composite score post-WU (89.12% [5.54%] vs 87.04% [5.35%]; P < .01) and at 15 minutes post-WU (89.55% [5.28%] vs 87.04%, P < .01) compared with pre-WU. However, no significant difference between these two post-WU scores (post-WU and 15 min post-WU) was found. For the PL-WU, participants demonstrated a significant decrease in the SEBT composite score at post-WU (85.95% [5.49%] vs 87.02% [5.73%]; P < .05); however, these scores increased significantly at 15 minutes post-WU (88.60% [5.42%] vs 87.02% [5.49%]; P < .05) compared with that at pre-WU. The SEBT composite scores are significantly higher in the DS-WU than in the PL-WU at both post-WU sessions (P < .05).

CONCLUSION

Both DS-WU and PL-WU could improve dynamic balance and may be recommended as WUs in athletes with ID; however, particular caution should be exercised immediately after the PL-WU.

Effects of stretching on muscle activation in gas cylinder handling

BACKGROUND

Previously, a stretching regimen was designed for manual material handling (MMH) of gas cylinders as a potential ergonomic solution for reducing occupational injury. No studies have made use of objective process measures, such as muscle activation levels, for evaluation of effects of stretching programs.

OBJECTIVE

Examine acute effects of stretching on muscle activation levels and driver perceived level of exertion in gas cylinder handling during simulated delivery operations.

METHODS

A within-subject experiment was conducted with eight male participants being subjected randomly to two conditions over a two-day period: stretching before delivery trials and no stretching. Surface electromyography and the Borg CR-10 scale for perceived exertion were used.

RESULTS

Generally, results were variable among muscle responses. The extensor muscle bundle in the forearm was found to show a significant decrease (p = 0.0464) in activation level because of stretching. The anterior deltoid and trapezius significantly increased (p < .0001) the EMG activation level with stretching. Also counter to expectations, participants rated perceived exertion significantly higher (p = 0.0423) for trials preceded by stretching.

CONCLUSIONS

This research indicates a muscle stretching regimen in advance of MMH activities has mixed effects on activation levels across muscles. It is possible that effects are attributable to body posture positions, or manner of muscle use, during actual work activities. Findings indicate that stretching prior to work activity does have an impact on specific muscle activation.

The Training and Development of Elite Sprint Performance: an Integration of Scientific and Best Practice Literature

Despite a voluminous body of research devoted to sprint training, our understanding of the training process leading to a world-class sprint performance is limited. The objective of this review is to integrate scientific and best practice literature regarding the training and development of elite sprint performance. Sprint performance is heavily dependent upon genetic traits, and the annual within-athlete performance differences are lower than the typical variation, the smallest worthwhile change, and the influence of external conditions such as wind, monitoring methodologies, etc. Still, key underlying determinants (e.g., power, technique, and sprint-specific endurance) are trainable. In this review, we describe how well-known training principles (progression, specificity, variation/periodization, and individualization) and varying training methods (e.g., sprinting/running, technical training, strength/power, plyometric training) are used in a sprint training context. Indeed, there is a considerable gap between science and best practice in how training principles and methods are applied. While the vast majority of sprint-related studies are performed on young team sport athletes and focus on brief sprints with maximal intensity and short recoveries, elite sprinters perform sprinting/running over a broad range of distances and with varying intensity and recovery periods. Within best practice, there is a stronger link between choice of training component (i.e., modality, duration, intensity, recovery, session rate) and the intended purpose of the training session compared with the “one-size-fits-all” approach in scientific literature. This review provides a point of departure for scientists and practitioners regarding the training and development of elite sprint performance and can serve as a position statement for outlining state-of-the-art sprint training recommendations and for generation of new hypotheses to be tested in future research.

Effects of flexibility combined with plyometric exercises vs isolated plyometric or flexibility mode in adolescent male hurdlers

BACKGROUND

This study aims to determine the effect of flexibility exercises combined with plyometrics in hurdles race, on physical fitness, motor skills (MS) and hip range of motion.

METHODS

Thirty-four male hurdlers, (age=15.7±0.7 years, body mass=59.7±2.3 kg, height=170.8±2.4 cm) were randomly assigned to four independent groups. The (Gflex+plyo), the (Gplyo), the (Gflex) and a control group (Gcon). All participants performed different tests: a test of right and left hip flexion (RHF, LHF) and extension (RHE, LHE), squat jump (SJ), countermovement jump (CMJ), stiffness jump (STFJ) and three (MS) exercises (running, hopping and leaping). A 60-m sprint on the hurdles was also performed.

RESULTS

The two-way analyses of covariance for repeated measures showed that Gflex+plyo increased significantly: the CMJ, performance on 60-m and showed higher performance in the between groups' comparison. The Gflex+plyo and Gflex showed the higher percentages of changes in flexibility (RHF: 3.2±1.3% and 3.0±2.1%; RHE: 6.4±2.4% and 9.4±4.1%, LHE: 8.4±3.4% and 7.8±4.3%, respectively). Gplyo increased significantly the LHF (3.9±1.4%) more than the other groups. In the between groups' comparison, Gplyo showed the higher percentage of change in STFJ (6.4±1.8%) and the Gflex+plyo showed the higher values in running and hopping (10.7±4.6% and 13.3±2.1%, respectively).

CONCLUSIONS

Specific stretching exercises combined with plyometrics may be more beneficial than other training strategies in young sprint-hurdlers. This may better improve physical fitness, hip range of motion and may increase different level of skills which may better improve performance in hurdles race.

Jogging and Practical-Duration Foam-Rolling Exercises and Range of Motion, Proprioception, and Vertical Jump in Athletes

CONTEXT

Foam-rolling exercises are frequently included in warmups due to their benefits for increasing range of motion (ROM). However, their effects on proprioception and vertical jump have not been analyzed and therefore remain unclear. Moreover, the effects of performing practical-duration foam-rolling exercises after typical warmup exercises such as jogging are unknown.

OBJECTIVE

To analyze the effects of jogging and practical-duration foam-rolling exercises on the ROM, knee proprioception, and vertical jump of athletes.

DESIGN

Randomized controlled study.

SETTING

Sports laboratory and university track.

PATIENTS OR OTHER PARTICIPANTS

Thirty athletes were randomly classified into an experimental group (EG) or control group (CG).

INTERVENTION(S)

The EG performed 8-minute jogging and foam-rolling exercises. The CG performed 8-minute jogging.

MAIN OUTCOME MEASURE(S)

Knee flexion, hip extension, active knee extension, ankle dorsiflexion (ADF), knee-joint position sense, and countermovement jump (CMJ) were evaluated before the intervention (baseline), after (post 0 min), and 10 minutes later.

RESULTS

The EG exhibited higher values for ADF and CMJ at post 0 min (ADF: P < .001, d = 0.88; CMJ: P < .001, d = 0.52) and 10 minutes later (ADF: P = .014, d = 0.41; CMJ: P = .006, d = 0.22) compared with baseline. Although the CG also showed increased CMJ at post 0 min (P = .044, d = 0.21), the EG demonstrated a greater increase (P = .021, d = 0.97). No differences were found in the remaining ROM variables (knee flexion, hip extension, active knee extension: P values > .05). For knee-joint position sense, no differences were found (P > .05).

CONCLUSIONS

Combining jogging and practical-duration foam rolling may increase ADF and CMJ without affecting knee proprioception and hip or knee ROM. Jogging by itself may slightly increase ADF and CMJ, but the results were better and were maintained after 10 minutes when foam rolling was added.

Physical Qualities Pertaining to Shorter and Longer Change-of-Direction Speed Test Performance in Men and Women

This study investigated relationships between shorter (505, change-of-direction (COD) deficit as a derived physical quality) and longer (Illinois agility test; IAT) COD tests with linear speed, lower-body power (multidirectional jumping), and strength in recreationally-trained individuals. Twenty-one males and 22 females (similar to collegiate club-sport and tactical athletes) were assessed in: 505 and COD deficit from each leg; IAT; 20 m sprint; vertical jump (VJ height, peak anaerobic power measured in watts (PAPw), power-to-body mass ratio); standing broad jump; lateral jump (LJ) from each leg; and absolute and relative isometric midthigh pull (IMTP) strength. Partial correlations calculated sex-determined relationships between the COD and performance tests, with regression equations calculated (p < 0.05). The 505 and IAT correlated with all tests except PAPw and absolute IMTP (r = ±0.43–0.71). COD deficit correlated with the LJ (r = −0.34–0.60). Left- and right-leg 505 was predicted by sex, 20 m sprint, and left-leg LJ (70–77% explained variance). Right-leg COD deficit was predicted by sex and left-leg LJ (27% explained variance). IAT was predicted by sex, 20 m sprint, right-leg LJ, and relative IMTP (84% explained variance). For individuals with limited training time, improving linear speed, and relative lower-body power and strength, could enhance shorter and longer COD performance.

Acute Effects of Stretching on Leg and Vertical Stiffness During Treadmill Running

Pappas, PT, Paradisis, GP, Exell, TA, Smirniotou, AS, Tsolakis, CK, and Arampatzis, A. Acute effects of stretching on leg and vertical stiffness during treadmill running. J Strength Cond Res 31(12): 3417-3424, 2017-The implementation of static (SS) and dynamic (DS) stretching during warm-up routines produces significant changes in biological and functional properties of the human musculoskeletal system. These properties could affect the leg and vertical stiffness characteristics that are considered important factors for the success of athletic activities. The aim of this study was to investigate the influence of SS and DS on selected kinematic variables, and leg and vertical stiffness during treadmill running. Fourteen men (age: 22.58 ± 1.05 years, height: 1.77 ± 0.05 m, body mass: 72.74 ± 10.04 kg) performed 30-second running bouts at 4.44 m·s, under 3 different stretching conditions (SS, DS, and no stretching). The total duration in each stretching condition was 6 minutes, and each of the 4 muscle groups was stretched for 40 seconds. Leg and vertical stiffness values were calculated using the "sine wave" method, with no significant differences in stiffness found between stretching conditions. After DS, vertical ground reaction force increased by 1.7% (p < 0.05), which resulted in significant (p < 0.05) increases in flight time (5.8%), step length (2.2%), and vertical displacement of the center of mass (4.5%) and a decrease in step rate (2.2%). Practical durations of SS and DS stretching did not influence leg or vertical stiffness during treadmill running. However, DS seems to result in a small increase in lower-limb force production which may influence running mechanics.

Skin temperature changes during muscular static stretching exercise

This study aimed to investigate the acute effects of stretching exercise on skin temperature, flexibility, passive muscle stiffness, and pain during hamstring stretching in healthy young subjects. Thirty-one participants (n=31) were randomly divided into 2 groups: an experimental group (EG, n=15), which was submitted to hamstring stretching exercise for 180 sec, and the control group (n=16), which was not exercised. Skin temperature (TsK) was collected in subjects' posterior thigh using a thermographic camera at 7 time points with intervals of 30 sec each: T0 (rest), T30, T60, T90, T120, T150, and T180. In addition, the knee range of motion, passive stiffness and muscle soreness (visual analogue scale) were recorded during the stretching procedure at the same times. The EG presented a small but progressive increase in TsK (30.8°C±0.6°C to 31.1°C±0.6°C, P<0.01), with an increased range of motion (P<0.01) and muscle soreness levels (P<0.01) during the gradual hamstring stretching protocol. Additionally, there was an increment of passive stiffness (P<0.01) that was partially reversed toward the end of the stretching period. This research presents evidence that constant, passive and progressive stretching of the hamstrings progressively increased the local TsK by about 0.3°C after 180 sec of stretching. These findings may help to understand the effects of repeated stress on the muscle-tendon unit and the role of muscle stretching in warm-up protocols and rehabilitation.

Flexibility responses to different stretching methods in young elite basketball players

Introduction

The aims of study were: 1) to verify the effectiveness of different stretching methods and training; 2) to compare the effects with only training on the flexibility of joints in basketball players.

Methods

30 males basketball players (age: 17±1yrs; BMI: 23.4±3.1), divided into 2 groups (15 experimental group - EG - and 15 control group, CG), participated to study. EG performed 5 different stretching method: passive stretching, active stretching, postural protocol, PNF and dynamic stretching. To assess differences (p<0.05) between groups, an ANOVA was applied to anthropometrics characteristic (age; height; weight and BMI) and flexibility performances (leg raise in a supine position; forward trunk bending). ANOVA for repeated measurements was conducted to asses differences in each group with time (i.e., pre-post).

Results

Results showed a variation linked to time (F=21.9; p<0.0001) and an effect of the treatment of the leg raise in a supine position test (F=25.1; p<0.0001). Also in flexion test of trunk, the average values could be linked to time of measurement (F=9.96; p<0.0001) and group (F=8.65; p<0.0001).

Conclusion

The results suggest that a specific different stretching protocol should be used in different part of body to offer performance benefit and decreasing of the incidents of injuries.

Level of evidence

IV.

The effects of different durations of static stretching within a comprehensive warm-up on voluntary and evoked contractile properties

Evidence for performance decrements following prolonged static stretching (SS) has led to a paradigm shift in stretching routines within a warm-up. Rather than SS, dynamic stretching (DS) and dynamic activity (DA) have replaced SS within warm-up routines. The objective of the present study was to compare the effect of differing lower limb SS durations (30 [SS30s], 60 [SS60s] or 120 s [SS120s] of SS per muscle group or no-stretch control) within a comprehensive warm-up protocol consisting of aerobic activity, DS and DA. Sixteen male participants completed the four stretching conditions in a randomized order, after a 5-min low-intensity (cycle) warm-up and before a DS/DA component on separate days. Tests included passive hip and knee ranges of motion (ROM), maximum voluntary knee extensor/flexor force, force produced at 100 ms (F100), vertical jump height and evoked knee extensor contractile properties. For hip flexion (hamstrings) ROM, SS120s provided the largest increase (5.6-11.7%) followed by SS60s (4.3-11.4%), control (4.4-10.6%) and SS30s (3.6-11.1%). For knee flexion (quadriceps) ROM, SS30s provided the largest increase (9.3-18.2%) followed by SS120s (6.5-16.3%), SS60s (7.2-15.2%) and control (6.3-15.2%). There were decreases in quadriceps F100 following SS in SS120s (29.6%) only. There were increases in vertical jump performance in the control (6.2%), SS60s (4.6%) and SS30s (3.3%). While 120 s SS per muscle increased ROM, even within a comprehensive warm-up routine, it also elicited notable performance decrements. However, moderate durations of SS were observed to improve ROM whilst either having negligible or beneficial (but not detrimental) effects on specific aspects of athletic performance.

Pre- and Post-Activity Stretching Practices of Collegiate Athletic Trainers in the United States

Popp, JK, Bellar, DM, Hoover, DL, Craig, BW, Leitzelar, BN, Wanless, EA, and Judge, LW. Pre- and post-activity stretching practices of collegiate athletic trainers in the United States. J Strength Cond Res 31(9): 2347-2354, 2017-The aim of the study was to investigate the knowledge and practices of collegiate-certified athletic trainers (ATs) in the United States. Participants (n = 521) were provided an overview of the study and a hyperlink to a web-based survey. The "pre- and post-activity practices in athletic training questionnaire" consisted of demographic items and elements to measure knowledge and practices related to pre- and post-activity stretching routines. In previous studies, the survey demonstrated construct validity, α = 0.722. Pearson chi-square test was used to evaluate goodness of fit, and kappa was calculated to measure agreement between items. Only 32.2% of ATs recommended dynamic stretching (DS) to be performed pre-activity, whereas a larger percentage (42.2%) recommended a combination of static stretching (SS) and DS. Athletic trainers reported that only 28.0% of athletes are performing DS before activity. Conversely, 60.6% of collegiate ATs recommended SS postexercise, and 61.0% of athletes agree and perform after workout SS (κ = 0.761, p < 0.001). Collegiate ATs seem to underuse the current research evidence, which indicates that DS is more beneficial than SS when used pre-activity, and ATs continue to regularly incorporate SS in their pre-activity routines. However, there is evidence that collegiate ATs in the United States emphasize SS postactivity in a manner consistent with current research.

Complementing Warm-up with Stretching Routines: Effects in Sprint Performance

The present study aimed to examine the effects of using static or dynamic stretching added to the common warm-up routine for short sprint distances and to repeated sprint performance. In 3 different sessions, 16 college-age men (n=10) and women (n=6) performed one of 3 warm-ups followed by a 2×60 m dash sprint time trial (5 min of rest) in a counterbalanced design. The control warm-up consisted of 10 min of light-intensity running, and the 2 experimental warm-ups included a static or dynamic stretching routine (5 exercises) in the control warm-up. Performance (time) and physiological variables (tympanic temperature, heart rate) were monitored. In the first 60 m time trial, there were no differences between the 3 warm-ups tested ( F =0.21, p=0.73; η _p² =0.01), as opposed to that observed in the second ( F =7.04, p<0.01; η _p² =0.32). The participants were 1.7% faster after the static stretching warm-up compared with the control warm-up. The sum of the time performed in the 2 sprints emphasizes these results, with better performances after the static stretching warm-up than the control (1%) or dynamic stretching warm-up (0.7%). These results suggest that including a set of static or dynamic stretching exercises may enhance sprinting performance. The better performance in the second trial after the warm-up including static stretching suggests that this type of stretching may positively influence repeated sprint performance (<10 s sprint).

Acute Effects of Static Stretching of Hamstring on Performance and Anterior Cruciate Ligament Injury Risk During Stop-Jump and Cutting Tasks in Female Athletes

Ruan, M, Zhang, Q, and Wu, X. Acute effects of static stretching of hamstring on performance and anterior cruciate ligament injury risk during stop-jump and cutting tasks in female athletes. J Strength Cond Res 31(5): 1241–1250, 2017—There is limited research investigating antagonist stretch. The purpose of this study was to evaluate the influence of static stretching of hamstrings (SSH) on performance and anterior cruciate ligament (ACL) injury risk during stop-jump and 180° cutting tasks. Twelve female college athletes (age 20.8 ± 0.7 years; height 1.61 ± 0.05 m; mass 54.25 ± 4.22 kg) participated in this study. Subjects performed stop-jump and 180° cutting tasks under 2 conditions: after warm-up with 4 × 30 seconds SSH or after warm-up without SSH. Three-dimensional kinematic and kinetic data as well as electromyography of biceps femoris, rectus femoris, vastus medialis, and gastrocnemius medialis were collected during testing. Static stretching of hamstrings significantly enhanced jump height by 5.1% (p = 0.009) but did not change the takeoff speed of cutting. No significant changes in peak knee adduction moment or peak anterior tibia shear force were observed with SSH regardless of the task. The peak lateral tibia shear force during cutting was significantly (p = 0.036) reduced with SSH. The co-contraction of hamstring and quadriceps during the preactivation (stop-jump: p = 0.04; cutting: p = 0.05) and downward phases (stop-jump: p = 0.04; cutting: p = 0.05) was significantly reduced after SSH regardless of the task. The results suggest that SSH enhanced the performance of stop-jump because of decreased co-contraction of hamstring and quadriceps but did not change the performance of cutting. In addition, SSH did not increase ACL injury risk during stop-jump and cutting tasks and even reduced medial-lateral knee loading during cutting.

The effects of a combined static-dynamic stretching protocol on athletic performance in elite Gaelic footballers: A randomised controlled crossover trial

OBJECTIVES

To determine the effect of three different static-dynamic stretching protocols on sprint and jump performance in Gaelic footballers.

DESIGN

Double-blind, controlled, crossover trial.

SETTING

Sports Institute research environment.

PARTICIPANTS

Seventeen male elite level Gaelic footballers, aged 18-30 years, completed three stretching protocols.

MAIN OUTCOME MEASURES

Athletic performance was measured by countermovement jump height and power, and timed 10 m, 20 m, and 40 m sprints.

RESULTS

Static stretching reduced sprint speed by 1.1% over 40 m and 1.0% over 20 m. Static stretching also reduced countermovement jump height by 10.6% and jump power by 6.4%. When static stretching was followed by dynamic stretching, sprint speed improved by 1.0% over 20 m and 0.7% over 40 m (p < 0.05). The static - dynamic stretching protocol also improved countermovement jump height by 8.7% (p < 0.01) and power by 6.7% (p < 0.01).

CONCLUSIONS

Static stretching reduces sprint speed and jump performance. Static stretching should be followed by dynamic stretching during warm-up to nullify any performance deficits caused by static stretching.

A2 Milk Enhances Dynamic Muscle Function Following Repeated Sprint Exercise, a Possible Ergogenic Aid for A1-Protein Intolerant Athletes?

Hyperaminoacidemia following ingestion of cows-milk may stimulate muscle anabolism and attenuate exercise-induced muscle damage (EIMD). However, as dairy-intolerant athletes do not obtain the reported benefits from milk-based products, A2 milk may offer a suitable alternative as it lacks the A1-protein. This study aimed to determine the effect of A2 milk on recovery from a sports-specific muscle damage model. Twenty-one male team sport players were allocated to three independent groups: A2 milk (n = 7), regular milk (n = 7), and placebo (PLA) (n = 7). Immediately following muscle-damaging exercise, participants consumed either A2 milk, regular milk or PLA (500 mL each). Visual analogue scale (muscle soreness), maximal voluntary isometric contraction (MVIC), countermovement jump (CMJ) and 20-m sprint were measured prior to and 24, 48, and 72 h post EIMD. At 48 h post-EIMD, CMJ and 20-m sprint recovered quicker in A2 (33.4 ± 6.6 and 3.3 ± 0.1, respectively) and regular milk (33.1 ± 7.1 and 3.3 ± 0.3, respectively) vs. PLA (29.2 ± 3.6 and 3.6 ± 0.3, respectively) (p < 0.05). Relative to baseline, decrements in 48 h CMJ and 20-m sprint were minimised in A2 (by 7.2 and 5.1%, respectively) and regular milk (by 6.3 and 5.2%, respectively) vs. PLA. There was a trend for milk treatments to attenuate decrements in MVIC, however statistical significance was not reached (p = 0.069). Milk treatments had no apparent effect on muscle soreness (p = 0.152). Following muscle-damaging exercise, ingestion of 500 mL of A2 or regular milk can limit decrements in dynamic muscle function in male athletes, thus hastening recovery and improving subsequent performance. The findings propose A2 milk as an ergogenic aid following EIMD, and may offer an alternative to athletes intolerant to the A1 protein.

Prevention of Hamstring Injuries in Collegiate Sprinters

BACKGROUND

No studies have been reported on how strength, agility, and flexibility training reduce the occurrence of hamstring injuries in sprinters. Therefore, a program for preventing hamstring injury in these athletes has not been established.

PURPOSE

To document the incidence of hamstring injuries during times when different prevention strategies were employed to see whether a particular prevention program reduced their occurrence.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

The study subjects were a total of 613 collegiate male sprinters trained by the same coach over 24 seasons. Tow training was used throughout the research period as a normal sprint training method. The hamstring injury prevention program evolved over time. From 1988 to 1991 (period 1), prevention focused on strength training alone; from 1992 to 1999 (period 2), a combination of strength and agility training was used; and from 2000 to 2011 (period 3), the program incorporated strength, agility, and flexibility training. The incidence of hamstring injuries was compared for each of the 3 prevention strategies.

RESULTS

The incidence of hamstring injuries per athlete-seasons was 137.9 for period 1, 60.6 for period 2, and 6.7 for period 3. A significant difference was observed in the incidence of hamstring injury according to the different prevention programs (χ²(2) = 31.78, P < .001, effect size: Cramer V = 0.23, 1 - β = 0.999). Residual analysis showed that the number of hamstring injuries for period 1 was significantly greater than the expected value (P < .01), whereas that for period 3 was significantly lower than the expected value (P < .01).

CONCLUSION

The incidence of hamstring injuries in sprinters decreased as agility and flexibility were added to strength training.

The Acute Effects of Static Stretching on Speed and Agility Performance Depend on Stretch Duration and Conditioning Level

Avloniti, A, Chatzinikolaou, A, Fatouros, IG, Avloniti, C, Protopapa, M, Draganidis, D, Stampoulis, T, Leontsini, D, Mavropalias, G, Gounelas, G, and Kambas, A. The acute effects of static stretching on speed and agility performance depend on stretch duration and conditioning level. J Strength Cond Res 30(10): 2767-2773, 2016-Although static stretching (SS) is an integral part of physical preparation before training and competition, its usefulness in regards to power performance improvement has been questioned. The aim of this study was to investigate the effect of 6 SS durations on speed and agility performance. According to a cross-over design, 34 trained men (age, 20.5 ± 1.4 years; height, 1.81 ± 0.2 m; weight, 77.2 ± 2.6 kg; body fat, 8.2 ± 2.6%) participated in a control session (no stretch) and 6 experimental conditions (10, 15, 20, 30, 40, and 60 seconds) performed in a randomized order. Performance in speed (10 and 20 m) and agility (T-test) was measured after the control and experimental conditions. Static stretching, consisting of stretches for hip extensors, hip adductors, knee extensors, knee flexors, and ankle sole flexors, was performed after light cardiovascular exercise (8 minutes). A 1-way repeated-measures analysis of variance showed that speed was improved only by SS of short duration (15/20 seconds), whereas agility remained unaffected by all SS trials. When participants' speed and agility level was taken into account, it was revealed that only those of moderate performance demonstrated an improved speed (in 15- and 20-second trials) and agility (in 10- and 15-second trials) performance. These results suggest that short-duration SS protocols induce an acute improvement of speed and agility performance, whereas longer-duration SS protocols have neither positive nor negative effect. Furthermore, it seems that individuals of lower speed and agility performance level are more likely to benefit by a short-duration SS protocol.

Acute Effect of Whole-Body Vibration Warm-up on Footspeed Quickness

Donahue, RB, Vingren, JL, Duplanty, AA, Levitt, DE, Luk, H-Y, and Kraemer, WJ. Acute effect of whole-body vibration warm-up on footspeed quickness. J Strength Cond Res 30(8): 2286-2291, 2016-The warm-up routine preceding a training or athletic event can affect the performance during that event. Whole-body vibration (WBV) can increase muscle performance, and thus the inclusion of WBV to the warm-up routine might provide additional performance improvements. The purpose of this investigation was to examine the acute effect of a WBV warm-up, using a vertical oscillating platform and a more traditional warm-up protocol on feet quickness in physically active men. Twenty healthy and physically active men (18-25 years, 22 ± 3 years, 176.8 ± 6.4 cm, 84.4 ± 11.5 kg, 10.8 ± 1.4% body fat) volunteered for this study. A 2 × 2 factorial design was used to examine the effect of 4 warm-up scenarios (no warm-up, traditional warm-up only, WBV warm-up only, and combined traditional and WBV warm-up) on subsequent 3-second Quick feet count test (QFT) performance. The traditional warm-up consisted of static and dynamic exercises and stretches. The WBV warm-up consisted of 60 seconds of vertical sinusoidal vibration at a frequency of 35 Hz and amplitude of 4 mm on a vibration platform. The WBV protocol significantly (p ≤ 0.0005, η = 0.581) augmented QFT performance (WBV: 37.1 ± 3.4 touches; no-WBV: 35.7 ± 3.4 touches). The results demonstrate that WBV can enhance the performance score on the QFT. The findings of this study suggest that WBV warm-up should be included in warm-up routines preceding training and athletic events which include very fast foot movements.

Actions of Two Bi-Articular Muscles of the Lower Extremity: A Review

The extremities of the human body contain several bi-articular muscles. The actions produced by muscles at the joints they cross are greatly influenced by joint moment arms and muscle length. These factors are dynamic and subject to change as joint angles are altered. Therefore, to more completely understand the actions of such muscles, the angles of both joints must be manipulated. This report reviews investigations, which have explored the actions of two bi-articular muscles of the lower extremities (gastrocnemius and rectus femoris) as the joints they cross are moved into various combinations of angles. The findings have both clinical and physical performance ramifications.

The effects of plantar flexor static stretching and dynamic stretching using an aero-step on foot pressure during gait in healthy adults: a preliminary study

[Purpose] The aim of this study was to examine whether plantar flexor static stretching and dynamic stretching using an Aero-Step results in changes in foot pressure during gait in healthy adults. [Subjects] Eighteen normal adults were randomly allocated to either a dynamic stretching using an Aero-Step group (DSUAS) group (n = 8) or a static stretching (SS) group (n = 10). [Methods] The DSUAS and SS participants took part in an exercise program for 15 minutes. Outcome measures were foot plantar pressure, which was measured during the subject’s gait stance phase; the asymmetric ratio of foot pressure for both feet; and the visual analogue scale (VAS) measured during the interventions. [Results] There were significant differences in the asymmetric ratio of foot pressure for both feet and VAS between the two groups after intervention. However, there were no significant differences in foot plantar pressure during the gait stance phase within both groups. [Conclusion] DSUSAS is an effective stretching method, as pain during it is lower than that with SS, which can minimize the asymmetric ratio of foot pressure for both feet during gait due to asymmetric postural alignment.

The effects of static stretching on speed and agility: One or multiple repetition protocols?

Although static stretching (SS) is utilized during warm-up before training and competition, the results about its effects on performance remain controversial. We examined whether performing a stretch of short-to-moderate duration (<60 sec) in a single repetition produces a similar or different effect on speed and agility performance from the effect which is produced while performing the same stretch in multiple repetitions of the same total duration. According to a repeated measurement design, 40 trained males were randomly assigned to either (1) a single repetition group or (2) a multiple repetition group. The participants in each group performed five trials: a control trial (no stretches were performed) and four experimental trials of SS protocols consisting of five exercises performed at either 20 sec (2 × 10 in the second group), 30 sec (3 × 10 in the second group), 40 sec (4 × 10 in the second group) or 60 sec (6 × 10 in the second group) of total duration. A two-way repeated measures analysis of variance showed that the participants in both group improved their speed performance in response to the 20-sec trial, whereas agility remained unaffected. Data analysis also revealed that the repetition number did not affect speed and agility performance. These data suggest that SS of short duration (<30 sec) may actually improve acute speed performance, whereas SS of moderate duration may not hamper speed and agility performance. Moreover, the effects of SS protocols are related to the total duration of each exercise and not to the number of repetitions in which each exercise is performed.

Static stretching can impair explosive performance for at least 24 hours

The aim of this study was to compare the effects of static vs. dynamic stretching (DS) on explosive performances and repeated sprint ability (RSA) after a 24-hour delay. Sixteen young male soccer players performed 15 minutes of static stretching (SS), DS, or a no-stretch control condition (CC) 24 hours before performing explosive performances and RSA tests. This was a within-subject repeated measures study with SS, DS, and CC being counterbalanced. Stretching protocols included 2 sets of 7 minutes 30 seconds (2 repetitions of 30 seconds with a 15-second passive recovery) for 5 muscle groups (quadriceps, hamstring, calves, adductors, and hip flexors). Twenty-four hours later (without any kind of stretching in warm-up), the players were tested for the 30-m sprint test (with 10- and 20-m lap times), 5 jump test (5JT), and RSA test. Significant differences were observed between CC, SS, and DS with 5JT (F = 9.99, p < 0.00, effect size [ES] = 0.40), 10-m sprint time (F = 46.52, p < 0.00, ES = 0.76), 20-m sprint time (F = 18.44, p < 0.000, ES = 0.55), and 30-m sprint time (F = 34.25, p < 0.000, ES = 0.70). The significantly better performance (p < 0.05) was observed after DS as compared with that after CC and SS in 5JT, and sprint times for 10, 20, and 30 m. In contrast, significantly worse performance (p < 0.05) was observed after SS as compared with that after CC in 5JT, and sprint times for 10, 20, and 30 m. With RSA, no significant difference was observed between different stretching protocols in the total time (F = 1.55, p > 0.05), average time (F = 1.53, p > 0.05), and fastest time (F = 2.30, p > 0.05), except for the decline index (F = 3.54, p < 0.04, ES = 0.19). Therefore, the SS of the lower limbs and hip muscles had a negative effect on explosive performances up to 24 hours poststretching with no major effects on the RSA. Conversely, the DS of the same muscle groups are highly recommended 24 hours before performing sprint and long-jump performances. In conclusion, the positive effects of DS on explosive performances seem to persist for 24 hours.

Effects of static and dynamic stretching on sprint and jump performance in boys and girls

The aim of this study was to investigate the acute effects of static (SS) and dynamic stretching (DS) on explosive power, flexibility, and sprinting ability of adolescent boys and girls and to report possible gender interactions. Forty-seven active adolescent boys and girls were randomly tested after SS and DS of 40 seconds on quadriceps, hamstrings, hip extensors, and plantar flexors; no stretching was performed at the control condition. Pretreatment and posttreatment tests examined the effects of stretching on 20-m sprint run (20 m), countermovement jump (CMJ) height, and sit and reach flexibility test. In terms of performance, SS hindered 20 m and CMJ in boys and girls by 2.5 and 6.3%, respectively. Dynamic stretching had no effect on 20 m in boys and girls but impaired CMJ by 2.2%. In terms of flexibility, both SS and DS improved performance with SS being more beneficial (12.1%) compared with DS (6.5%). No gender interaction was found. It can therefore be concluded that SS significantly negates sprinting performance and explosive power in adolescent boys and girls, whereas DS deteriorates explosive power and has no effect on sprinting performance. This diversity of effects denotes that the mode of stretching used in adolescent boys and girls should be task specific.

Effects of stretching on performances involving stretch-shortening cycles

BACKGROUND

Alongside its role in athletic conditioning, stretching has commonly been integrated in warm-up routines prior to athletic performance. Numerous studies have reported detrimental acute effects on strength following stretching. Consequently, athletes have been recommended to discontinue stretching as part of warm-ups. In contrast, studies indicate that chronic stretching performed as a separate bout from training or competition may enhance performance. However, the influence of stretching on complex performances has received relatively little attention.

OBJECTIVE

The purpose of this study was to review both the acute and chronic effects of stretching on performances involving the stretch-shortening cycle (SSC).

METHODS

A systematic search for literature was undertaken (January 2006-December 2012) in which only randomized controlled trials (RCTs) or studies with repeated measures designs were included. The Physiotherapy Evidence Database (PEDro) rating scale was used for quality assessment of the evidence.

RESULTS

The review included 43 studies, from which conflicting evidence emerged. Approximately half of the studies assessing the acute effect of static stretching reported a detrimental effect on performance, while the remainder found no effect. In contrast, dynamic stretching showed no negative effects and improved performance in half of the trials. The effect size associated with static and dynamic stretching interventions was commonly low to moderate, indicating that the effect on performance might be limited in practice. Factors were identified that might have contributed to the conflicting results reported across studies, such as type of SSC performance and carrying out dynamic activity between the stretching bout and performance. Few studies since 2006 have addressed the chronic effect of stretching on functional and sports performance. Although negative effects were not reported, robust evidence of the overall beneficial effects within current bibliographic databases remains elusive. Plausible mechanisms for the observed effects from stretching are discussed, as well as possible factors that may have contributed to contradictory findings between studies.

LIMITATIONS

Considerable heterogeneity in study design and methods makes comparison between studies challenging. No regression analysis of the contribution of different predictors to variation between trials had previously been performed. Hence, predictors had to be selected on the basis of a qualitative analysis of the predictors that seemed most influential, as well as being identified in previous narrative reviews.

CONCLUSION

Different types of stretching have differential acute effects on SSC performances. The recommended volume of static stretching required to increase flexibility might induce a negative acute effect on performances involving rapid SSCs, but the effect sizes of these decrements are commonly low, indicating that the acute effect on performance might be limited in practice. No negative acute effects of dynamic stretching were reported. For athletes that require great range of motion (ROM) and speed in their sport, long-term stretching successfully enhances flexibility without negatively affecting performance. Acute dynamic stretching may also be effective in inducing smaller gains in ROM prior to performance without any negative effects being observed.

Mechanical analysis of the acute effects of a heavy resistance exercise warm-up on agility performance in court-sport athletes

The purpose of this study was to determine the acute effects of heavy resistance exercise on agility performance in court-sport athletes. Five men (age: 20.6 ± 1.9 years; body mass: 79.36 ± 11.74 kg; body height: 1.93 ± 0.09 m) and five women (age 21.2 ± 2.7 years; body mass: 65.8 ± 10.18 kg; body height 1.77 ± 0.08 m) volunteered to participate in the present study. All subjects were NCAA Division II athletes who currently participated in tennis or basketball and all had previous resistance training experience of at least one year. In a counterbalanced design, agility performance during a 10 m shuttle test was assessed following either a dynamic warm-up (DW) or heavy resistance warm-up (HRW) protocol. The HRW protocol consisted of three sets of squats at 50, 60, and 90% of 1-RM. Agility performance was captured using an eight camera motion analysis system and the mechanical variables of stride length, stride frequency, stance time, flight time, average ground reaction force, as well as agility time were recorded. No significant differences were reported for the HRW and DW protocols for any of the mechanical variables (p>0.05), although there was a trend towards the HRW protocol producing faster agility times compared to the control protocol (p = 0.074). Based on the trend towards a significant effect, as well as individual results it is possible that HRW protocols could be used as an acute method to improve agility performance in some court-sport athletes.

An investigation into the effect of a pre-performance strategy on jump performance

The aim of this study was to explore the effect that different components, making up a commonly used pre-performance preparation strategy, have on jump height performance. Sixteen male collegiate athletes (age, 21.38 ± 0.52 years; height, 1.79 ± 0.07 m; and body mass, 75.1 ± 5.26 kg) performed a preparation strategy involving a cycle ergometer warm-up, followed by a dynamic stretch component, and finishing with heavy back squats. This intervention was repeated to test countermovement, squat or drop jump performance after each component of the preparation strategy, with electromyographic activity measured during each jump test. Significant increases (p < 0.05) in jump height and electromyographic activity were noted, with a stepwise increase in performance from pre- to post-warm-up, increased further by the dynamic stretch component and again increased after the back squat. It was also noted that the increases in performance, attributed to the stretch and lift components, were significantly greater (p < 0.05) than the increases in jump height associated with the active warm-up. It seems likely that the initial active warm-up raised core temperature, helping to increase the jump performance. The specific movements employed in the stretch and lift interventions seemed to potentiate the agonistic muscles involved in jumping, shown by increases in electromyographic activity in the prime movers for the jumps explored. This could be an example of postactivation potentiation, where muscles are primed to increase performance beyond changes linked to an active warm-up.

The differential effects of PNF versus passive stretch conditioning on neuromuscular performance

The effects of flexibility conditioning on neuromuscular and sensorimotor performance were assessed near to full knee extension (25°). Eighteen males who were randomly assigned into two groups underwent eight weeks (three-times per week) of flexibility conditioning (hip region/knee flexor musculature; dominant limb) involving either proprioceptive neuromuscular facilitation (PNF) (n=9) or passive stretching (PASS) (n=9). Both modes of flexibility conditioning are popular within contemporary exercise and clinical settings and have demonstrated efficacy in improving range of motion. The contralateral limb and a prior 'no exercise' condition were used as controls. The PNF and PASS modes of conditioning improved passive hip flexibility to a similar extent (mean 19.3% vs. baseline, intervention limb, p<0.01) but did not alter knee flexor strength (overall mean 309.6±81 N) or sensorimotor performance (force and positional errors: 2.3±8.2% and 0.48±7.1%). Voluntary and magnetically evoked electromechanical delays (EMDV and EMDE, respectively) were increased but to a greater extent following PASS compared to PNF (PASS: 10.8% and 16.9% lengthening of EMDV and EMDE, respectively vs. PNF: 3.2% and 6.2%, p<0.01).The attenuated change to electromechanical delay (EMD) performance during PNF conditioning suggests a preserved capability for rapid muscle activation, which is important in the maintenance of dynamic joint stability. That PNF was also equally efficacious in flexibility conditioning would suggest that this mode of flexibility training should be used over passive to help preserve dynamic joint stability capabilities at this extended and vulnerable joint position.

Effect of various warm-up protocols on jump performance in college football players

The purpose of this study was to identify the effects of warm-up strategies on countermovement jump performance. Twenty-nine male college football players (age: 19.4 ± 1.1 years; body height: 179.0 ± 5.1 cm; body mass: 73.1 ± 8.0 kg; % body fat: 11.1 ± 2.7) from the Tuzla University underwent a control (no warm-up) and different warm-up conditions: 1. general warm-up; 2. general warm-up with dynamic stretching; 3. general warm-up, dynamic stretching and passive stretching; 4. passive static stretching; 5. passive static stretching and general warm-up; and, 6. passive static stretching, general warm-up and dynamic stretching. Countermovement jump performance was measured after each intervention or control. Results from one way repeated measures ANOVA revealed a significant difference on warm-up strategies at F (4.07, 113.86) = 69.56, p < 0.001, eta squared = 0.72. Bonferonni post hoc revealed that a general warm-up and a general warm-up with dynamic stretching posted the greatest gains among all interventions. On the other hand, no warm-up and passive static stretching displayed the least results in countermovement jump performance. In conclusion, countermovement jump performance preceded by a general warm-up or a general warm-up with dynamic stretching posted superior gains in countermovement jump performance.

Effect of acute static stretch on maximal muscle performance: a systematic review

INTRODUCTION

The benefits of preexercise muscle stretching have been recently questioned after reports of significant poststretch reductions in force and power production. However, methodological issues and equivocal findings have prevented a clear consensus being reached. As no detailed systematic review exists, the literature describing responses to acute static muscle stretch was comprehensively examined.

METHODS

MEDLINE, ScienceDirect, SPORTDiscus, and Zetoc were searched with recursive reference checking. Selection criteria included randomized or quasi-randomized controlled trials and intervention-based trials published in peer-reviewed scientific journals examining the effect of an acute static stretch intervention on maximal muscular performance.

RESULTS

Searches revealed 4559 possible articles; 106 met the inclusion criteria. Study design was often poor because 30% of studies failed to provide appropriate reliability statistics. Clear evidence exists indicating that short-duration acute static stretch (<30 s) has no detrimental effect (pooled estimate = -1.1%), with overwhelming evidence that stretch durations of 30-45 s also imparted no significant effect (pooled estimate = -1.9%). A sigmoidal dose-response effect was evident between stretch duration and both the likelihood and magnitude of significant decrements, with a significant reduction likely to occur with stretches ≥ 60 s. This strong evidence for a dose-response effect was independent of performance task, contraction mode, or muscle group. Studies have only examined changes in eccentric strength when the stretch durations were >60 s, with limited evidence for an effect on eccentric strength.

CONCLUSIONS

The detrimental effects of static stretch are mainly limited to longer durations (≥ 60 s), which may not be typically used during preexercise routines in clinical, healthy, or athletic populations. Shorter durations of stretch (<60 s) can be performed in a preexercise routine without compromising maximal muscle performance.

The effect of warm-ups incorporating different volumes of dynamic stretching on 10- and 20-m sprint performance in highly trained male athletes

Recently, athletes have transitioned from traditional static stretching during warm-ups to incorporating dynamic stretching routines. However, the optimal volume of dynamic drills is yet to be identified. The aim of this repeated-measures study was to examine varying volumes (1, 2, and 3 sets) of active dynamic stretching (ADS) in a warm-up on 10- and 20-m sprint performance. With a within-subject design, 16 highly trained male participants (age: 20.9 ± 1.3 years; height: 179.7 ± 5.7 cm; body mass: 72.7 ± 7.9 kg; % body fat: 10.9 ± 2.4) completed a 5-minute general running warm-up before performing 3 preintervention measures of 10- to 20-m sprint. The interventions included 1, 2, and 3 sets of active dynamic stretches of the lower-body musculature (gastrocnemius, gluteals, hamstrings, quadriceps, and hip flexors) performed approximately 14 times for each exercise while walking (ADS1, ADS2, and ADS3). The active dynamic warm-ups were randomly allocated before performing a sprint-specific warm-up. Five minutes separated the end of the warm-up and the 3 postintervention measures of 10- to 20-m sprints. There were no significant time, condition, and interaction effects over the 10-m sprint time. For the 0- to 20-m sprint time, a significant main effect for the pre-post measurement (F = 10.81; p < 0.002), the dynamic stretching condition (F = 6.23; p = 0.004) and an interaction effect (F = 41.19; p = 0.0001) were observed. A significant decrease in sprint time (improvement in sprint performance) post-ADS1 (2.56%, p = 0.001) and post-ADS2 (2.61%, p = 0.001) was observed. Conversely, the results indicated a significant increase in sprint time (sprint performance impairment) post-ADS3 condition (2.58%, p = 0.001). Data indicate that performing 1-2 sets of 20 m of active dynamic stretches in a warm-up can enhance 20-m sprint performance. The results delineated that 3 sets of ADS repetitions could induce acute fatigue and impair sprint performance within 5 minutes of the warm-up.

The acute effects of different stretching exercises on jump performance

The purpose of this study was to demonstrate the short-term effects of different stretching exercises during the warm-up period on the lower limbs. A controlled, crossover clinical study involving 49 volunteers (14 women and 35 men; mean age: 20.4 years) enrolled in a "physical and sporting activities monitor" program. The explosive force was assessed using the Bosco test. The protocol was as follows: The test involved a (pre) jump test, general warm-up, intervention and (post) jump test. Each volunteer was subjected to each of the 5 interventions (no stretching [NS] and stretching: static passive stretching [P]; proprioceptive neuromuscular facilitation [PNF] techniques; static active stretching in passive tension [PT]; static active stretching in active tension [AT]) in a random order. The jump test was used to assess the squat jump, countermovement jump (CMJ), elasticity index (EI), and drop jump. An intragroup statistical analysis was performed before and after each intervention to compare the differences between the different stretching exercises. An intergroup analysis was also performed. Significant differences (p < 0.05) were found between all variables for the interventions "P," "PNF," and "TA" in the intragroup analysis, with each value being higher in the postjump test. Only the "P" intervention showed a significant difference (p = 0.046) for "EI," with the postvalue being lower. Likewise, significant differences (p < 0.05) were observed for the "CMJ" measurements during the intergroup analysis, especially between "NS" and the interventions "P," "PNF," "AT," and "PT," with each value, particularly that for "AT," being higher after stretching. The results of this study suggest that static active stretching in AT can be recommended during the warm-up for explosive force disciplines.