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Background: When recommending avoidance of static stretching prior to athletic performance, authors and practitioners commonly refer to available systematic reviews. However, effect sizes (ES) in previous reviews were extracted in major part from studies lacking control conditions and/or pre–post testing designs. Also, currently available reviews conducted calculations without accounting for multiple study outcomes, with ES: –0.03 to 0.10, which would commonly be classified as trivial. Methods: Since new meta-analytical software and controlled research articles have appeared since 2013, we revisited the available literatures and performed a multilevel meta-analysis using robust variance estimation of controlled pre–post trials to provide updated evidence. Furthermore, previous research described reduced electromyography activity—also attributable to fatiguing training routines—as being responsible for decreased subsequent performance. The second part of this study opposed stretching and alternative interventions sufficient to induce general fatigue to examine whether static stretching induces higher performance losses compared to other exercise routines. Results: Including 83 studies with more than 400 ES from 2012 participants, our results indicate a significant, small ES for a static stretch-induced maximal strength loss (ES = –0.21, p = 0.003), with high magnitude ES (ES = –0.84, p = 0.004) for stretching durations ≥60 s per bout when compared to passive controls. When opposed to active controls, the maximal strength loss ranges between ES: –0.17 to –0.28, p < 0.001 and 0.040 with mostly no to small heterogeneity. However, stretching did not negatively influence athletic performance in general (when compared to both passive and active controls); in fact, a positive effect on subsequent jumping performance (ES = 0.15, p = 0.006) was found in adults. Conclusion: Regarding strength testing of isolated muscles (e.g., leg extensions or calf raises), our results confirm previous findings. Nevertheless, since no (or even positive) effects could be found for athletic performance, our results do not support previous recommendations to exclude static stretching from warm-up routines prior to, for example, jumping or sprinting.

Abstract Background The majority of studies that explore changes in musculature following resistance training interventions or examine atrophy due to immobilization or sarcopenia use ultrasound imaging. While most studies assume acceptable to excellent reliability, there seems to be unawareness of the existing absolute measurement errors. As early as 1998, methodological research addressed a collective unawareness of the random measurement error and its practical indications. Referring to available methodological approaches, within this work, we point out the limited value of focusing on relative, correlation-based reliability indices for the interpretability in scientific research but also for clinical application by assessing 1,512 muscle thickness values from more than 400 ultrasound images. To account for intra- and inter-day repeatability, data were collected on two consecutive days within four testing sessions. Commonly-stated reliability values (ICC, CV, SEM and MDC) were calculated, while evidence-based agreement analyses were applied to provide the accompanied systematic and random measurement error. Results While ICCs in the range of 0.832 to 0.998 are in accordance with the available literature, the mean absolute percentage error ranges from 1.34 to 20.38% and the mean systematic bias from 0.78 to 4.01 mm (all p ≤ 0.013), depending on the measurement time points chosen for data processing. Conclusions In accordance with prior literature, a more cautious interpretation of relative reliability values should be based on included systematic and random absolute measurement scattering. Lastly, this paper discusses the rationale for including different measurement error statistics when determining the validity of pre-post changes, thus, accounting for the certainty of evidence.

Background: Acute improvement in range of motion (ROM) is a widely reported effect of stretching and foam rolling, which is commonly explained by changes in pain threshold and/or musculotendinous stiffness. Interestingly, these effects were also reported in response to various other active and passive interventions that induce responses such as enhanced muscle temperature. Therefore, we hypothesized that acute ROM enhancements could be induced by a wide variety of interventions other than stretching or foam rolling that promote an increase in muscle temperature. Methods: After a systematic search in PubMed, Web of Science, and SPORTDiscus databases, 38 studies comparing the effects of stretching and foam rolling with several other interventions on ROM and passive properties were included. These studies had 1134 participants in total, and the data analysis resulted in 140 effect sizes (ESs). ES calculations were performed using robust variance estimation model with R-package. Results: Study quality of the included studies was classified as fair (PEDro score = 4.58) with low to moderate certainty of evidence. Results showed no significant differences in ROM (ES = 0.01, p = 0.88), stiffness (ES = 0.09, p = 0.67), or passive peak torque (ES = –0.30, p = 0.14) between stretching or foam rolling and the other identified activities. Funnel plots revealed no publication bias. Conclusion: Based on current literature, our results challenge the established view on stretching and foam rolling as a recommended component of warm-up programs. The lack of significant difference between interventions suggests there is no need to emphasize stretching or foam rolling to induce acute ROM, passive peak torque increases, or stiffness reductions.

Abstract Background Abnormal posture (e.g. loss of lordosis) has been associated with the occurrence of musculoskeletal pain. Stretching tight muscles while strengthening the antagonists represents the most common method to treat the assumed muscle imbalance. However, despite its high popularity, there is no quantitative synthesis of the available evidence examining the effectiveness of the stretch-and-strengthen approach. Methods A systematic review with meta-analysis was conducted, searching PubMed, Web of Science and Google Scholar. We included controlled clinical trials investigating the effects of stretching or strengthening on spinal and lumbopelvic posture (e.g., pelvic tilt, lumbar lordosis, thoracic kyphosis, head tilt) in healthy individuals. Effect sizes were pooled using robust variance estimation. To rate the certainty about the evidence, the GRADE approach was applied. Results A total of 23 studies with 969 participants were identified. Neither acute (d = 0.01, p = 0.97) nor chronic stretching (d=-0.19, p = 0.16) had an impact on posture. Chronic strengthening was associated with large improvements (d=-0.83, p = 0.01), but no study examined acute effects. Strengthening was superior (d = 0.81, p = 0.004) to stretching. Sub-analyses found strengthening to be effective in the thoracic and cervical spine (d=-1.04, p = 0.005) but not in the lumbar and lumbopelvic region (d=-0.23, p = 0.25). Stretching was ineffective in all locations (p > 0.05). Conclusion Moderate-certainty evidence does not support the use of stretching as a treatment of muscle imbalance. In contrast, therapists should focus on strengthening programs targeting weakened muscles.

IntroductionClinically, knowing whether a static stretching (SS) intervention program conducted for several weeks can reduce passive muscle stiffness is important. Still, only a few previous studies have evaluated the chronic effects of an SS intervention program in older adults, and the potential relationship between ROM changes and muscle stiffness changes is still unclear. This study aimed to investigate the effects of a 10- week SS intervention partially supervised program on joint range of motion (ROM) and tissue hardness in older adults.MethodsThe SS intervention program was conducted at least three times a week for 10 weeks in the ankle plantar flexor muscles of 24 community-dwelling older adults (73.8 ± 5.1 years; height: 156.0 ± 6.8 cm; body mass: 52.7 ± 8.0 kg). The SS intervention program consisted of 4 × 30-s repetitions. Ankle joint dorsiflexion (DF) ROM and tissue hardness of the medial gastrocnemius were measured before and after the 10-week SS intervention program.Results and discussionThe results showed that the 10-week SS intervention program significantly increased DF ROM (+9°, p

Introduction One-third of individuals over the age of 65 fall at least once per year. Lacroix et al. (2017) shows that supervised strength training improves balance and muscle strength, which might beneficially impact the risk of falls. The American Geriatrics Society and the American Academy of Orthopaedic Surgeons recommend resistance training to improve balance (McMurdo, 2002). However, administrative burden such as limited mobility can reduce engagement among older adults for common training routines and call for the development of alternatives, but no review has investigated whether stretching has acute or chronic effects on balance. Purpose Since recent studies pointed out that high volumes of stretch could be used interchangeable with resistance training, but can be safely used without supervision (Warneke et al., 2024), this systematic review with meta-analysis investigate the effects of stretching on balance parameters across the lifespan. Methods PubMed, Web of Science, and Scopus were screened for (randomized) controlled trials (RCTs) on acute and chronic stretching effects, with subgroup analyses for a) stretching types, and b) different balance tasks, e.g., standing as still as possible on a force plate to measure the center of pressure (CoP) with eyes open (EO) and eyes closed, as well as Y-balance and star excursion test were conducted. We assessed risk of bias, while certainty of evidence was assessed in accordance with the GRADE working group guidelines. Statistical calculations were performed with R (version 4.2.3). Effect sizes (ES) were quantified using the packages Robumeta and Meta. Results Out of 18 acute studies, 15 compared acute stretching effects to passive control, while 4 performed comparisons to an active control, resulting in small magnitude effects on CoP/Sway EO (ES: 0.21, p = 0.03). Out of eleven chronic studies, seven had passive control, and 5 an active control group, resulting in moderate balance improvements with ES reaching 0.63, p = 0.04 for CoP/Sway EO. The remaining effects remained unsignificant (p = 0.091 - 1). Discussion While flexibility is commonly performed to enhance flexibility, it can also positively impact balance in some conditions. While our research question was derived via the positive association between strength and balance (Muehlbauer et al., 2015), and the possibility to use high volume stretching to enhance strength (Warneke et al., 2024), neither used included studies stretching durations of sufficient length, nor was strength measured as an outcome. It is noteworthy that most of the included studies did not interpret stretching effects in the light of underlying physiology, but on a more phenomenological basis, making a final conclusion about potential mechanisms complicated. Conclusion Although our results indicated beneficial effects of stretching on balance in some subgroup analyses, underlying mechanisms remain speculative, yet. There is a dearth of high-quality randomized controlled studies, using reasonable stretching times to enhance strength and muscle size via stretch to check whether there is the potential to use stretch-mediated hypertrophy and strength increases as a viable alternative to common resistance training and balance programs when aiming to enhance balance. References Lacroix, A., Hortobágyi, T., Beurskens, R., & Granacher, U. (2017). Effects of supervised vs. unsupervised training programs on balance and muscle strength in older adults: A systematic review and meta-analysis. Sports Medicine, 47(11), 2341–2361. https://doi.org/10.1007/s40279-017-0747-6 McMurdo, M. E. T. (2002). ‘Guideline for the prevention of falls in older persons’: Essential reading. Age and Ageing, 31(1), 13–14. https://doi.org/10.1093/ageing/31.1.13 Muehlbauer, T., Gollhofer, A., & Granacher, U. (2015). Associations between measures of balance and lower-extremity muscle strength/power in healthy individuals across the lifespan: A systematic review and meta-analysis. Sports Medicine, 45(12), 1671–1692. https://doi.org/10.1007/s40279-015-0390-z Warneke, K., Lohmann, L. H., Behm, D. G., Wirth, K., Keiner, M., Schiemann, S., & Wilke, J. (2024). Effects of chronic static stretching on maximal strength and muscle hypertrophy: A systematic review and meta-analysis. Sports Medicine – Open, 10, Article 45. https://doi.org/10.1186/s40798-024-00706-8

Introduction While all running athletes aim to cover the prescribed distance as fast as possible, the physiological and anatomical profiles of athletes are completely different between the disciplines. While sprint athletes have to exert maximal force in the smallest possible time window, the long-distance runner strives for the most economical movement pattern possible (Barnes & Kilding, 2015). Therefore, defined as oxygen uptake at a velocity at a prescribed percentage of the vVO2max, running economy (RE) has been identified as a decisive performance parameter (Saunders et al., 2004). One identified parameter which moderates RE was Achilles tendon stiffness. While stretching frequently used in warm-ups, it also decreases tissue stiffness. Objective: While some authors recommended the avoidance of stretching prior to running (Wilson et al., 2010), others found no affected economy in response to stretching. To address this research gap, this study was conducted to pool available stretching effects on RE. Methods A systematic search was conducted using MEDLINE/PubMed, Web of Science and Scopus (inception to April, 2024), which was supplemented by a manual search in Google Scholar and reference lists of identified studies. To account for multiple dependent study outcomes, robust variance estimation meta-analysis model was chosen to quantify pooled effect sizes. Controlled acute and chronic studies were included if they were performed in young, healthy participants on RE-parameter (energy/O2-consumption at a prescribed velocities determined at a percentage of VO2max (vVO2). Studies without a control group, patients or without the metabolic parameters were excluded. The PEDro scale and GRADE criteria were applied to evaluate the risk of bias and certainty of evidence, respectively. Results A total of 16 studies were investigated, with 14 studies (6 static stretching, 6 dynamic stretching and 2 static/dynamic stretching) addressing acute effects with 169 participants and 33 effect sizes (ES) matched the inclusion criteria. With a PEDro score of 4.88, study quality was rated fair. Overall, there was a low certainty of evidence without confirming any effect of stretching on RE, with overall group effect of ES = 0.007, −0.15 to 0.17 [95% CI], p = 0.93, τ2 = 0, W2 = 0, static group effect of ES = –0,22, –0,40 to 0,70 [95% CI], p = 0.3, τ2 = 0.18, W2 = 0 and dynamic group effect of ES = –0,07, −0.22 to 0.09 [95% CI], p = 0.35, τ2 = 0, W2 = 0, determined at vVO2 65% - 90%. Discussion Currently, there is no evidence supporting previous recommendations to avoid stretching before running due to reduced RE. However, several methodological limitations, such as high heterogeneity in the velocity used in RE determination, small study sample sizes and comparatively short stretching durations without intensity quantification and a lack of pre-post comparisons bias the certainty of evidence. Accordingly, there is a demand for high quality research that controls underlying mechanisms. References Barnes, K. R., & Kilding, A. E. (2015). Running economy: Measurement, norms, and determining factors. Sports Medicine – Open, 1, Article 8. https://doi.org/10.1186/s40798-015-0007-y Saunders, P., Pyne, D., Telford, R., & Hawley, J. (2004). Factors affecting running economy in trained distance runners. Sports Medicine, 34, 465–485. https://doi.org/10.2165/00007256-200434070-00005 Wilson, J. M., Hornbuckle, L. M., Kim, J.-S., Ugrinowitsch, C., Lee, S.-R., Zourdos, M. C., Sommer, B., & Panton, L. B. (2010). Effects of atatic atretching on wnergy cost and running endurance performance. The Journal of Strength & Conditioning Research, 24(9), 2274-2279. https://doi.org/10.1519/JSC.0b013e3181b22ad6

The American College of Sports Medicine classifies flexibility as one out of 5 important health-related parameters that should be addressed in preventive and therapeutic training programs (Garber et al., 2011). Due to its importance in health and athletic performance development, there is an increasing number of studies to figure out flexibility training interventions as well as underlying mechanisms. While several exercise modalities are available, stretching and foam rolling (FR) are the most common training routines to improve range of motion (ROM). Interestingly, acute and chronic effects are mainly attributed to very similar mechanisms, more specifically, improved stretch tolerance and/or structural adaptations such as stiffness reductions in the muscle, the tendon, or the muscle-tendon complex (Takeuchi et al., 2023). Since stretching and FR seem to induce similar effect sizes in acute flexibility, authors suggested the replacement of static stretching to FR in movement preparation routines to avoid the stretch-induced force deficit, thus, impairments of subsequent strength related performance. Similarly, when discussing chronic flexibility routine effects, literature suggests task specificity. Therefore, increased ROM was attributed to specific stretch/foam rolling induced stiffness and passive peak torque changes. Unfortunately, statements developed from used research designs are incomprehensive. When referring to acute stretching of foam rolling effects that can be extracted from numerous systematic reviews, conclusions were drawn from comparisons to passive controls. This, however, does exclusively allow statements that stretching/FR was effective compared to doing nothing, however, does not exclude general warm-up effects, induced by muscle activity. Referring to William of Ockham (1287 – 1347), one popular philosopher from the United Kingdom, the most obvious explanatory approach would be the most likely one. In medicine diagnostics, this statement is metaphorically described as “when hearing hoof beats from behind, expect horses, not zebras”. Therefore, since both routines enhance temperature, the most likely explanation suggest acute ROM increases could rely on general warm-up effects instead of task-specific adaptations. Similarly, for chronic effects, literature suggests that ROM can be increased by several alternative interventions, e.g. full ROM resistance training, indicating shared mechanisms. Both interventions share underlying physiological mechanisms, such as inducing mechanical tension in high muscle lengths. Consequently, we extensively discussed available evidence in our published research. Key findings will be presented to challenge current paradigms (Warneke et al., 2024). References Garber, C. E., Blissmer, B., Deschenes, M. R., Franklin, B. A., Lamonte, M. J., Lee, I.-M., Nieman, D. C., & Swain, D. P. (2011). Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults. Medicine & Science in Sports & Exercise, 43(7), 1334–1359. https://doi.org/10.1249/MSS.0b013e318213fefb Takeuchi, K., Nakamura, M., Fukaya, T., Konrad, A., & Mizuno, T. (2023). Acute and long-term effects of static stretching on muscle-tendon unit stiffness: A systematic review and meta-analysis. Journal of Sports Science and Medicine, 22, 465–475. https://doi.org/10.52082/jssm.2023.465 Warneke, K., Behm, D. G., Alizadeh, S., Hillebrecht, M., Konrad, A., & Wirth, K. (2024). Discussing conflicting explanatory approaches in flexibility training under consideration of physiology - A narrative review. Sports Medicine, 54, 1785-1799. https://doi.org/10.1007/s40279-024-02043-y

IntroductionBalance is a multifactorial construct with high relevance in, e.g., everyday life activities. Apart from sensorimotor control, muscle strength and size are positively linked with balance performance. While commonly trained for via resistance training, stretch training has emerged as a potential substitution in specific conditions. However, no review has investigated potential effects of stretching on balance, yet.MethodsPubMed, Web of Science and Scopus were searched with inception to February, 2024. Studies were included if they examined acute and/or chronic effects of any stretching type against passive and/or active controls on balance parameters – without any population-related restrictions concerning sex/gender, age, health status, activity level. Methodological quality was assessed using PEDro scale. Meta-analyses were performed if two or more studies reported on the same outcome. Certainty of evidence was determined based on GRADE criteria.ResultsEighteen acute and eleven chronic effect studies were included. Stretching studies exhibited significant improvements for sway parameters with eyes open against passive controls of moderate magnitude for chronic (ES: 0.63, p = 0.047) and of small magnitude for acute studies (ES: 0.21, p = 0.032). Most other subgroups against passive controls as well as actively-controlled comparisons resulted in trivial and/or non-significant effects.ConclusionEven though some pooled effects slightly reached the level of significance, the overall results are biased by (very) low certainty of evidence (GRADE criteria downgrading for risk of bias, imprecision, publication bias). Moderators suggested by literature (strength, muscle size, flexibility, proprioception) were rarely assessed, which prevents conclusive final statements and calls for further, high quality evidence to clarify potential mechanisms–if any exist.

IntroductionWhile maximum strength diagnostics are applied in several sports and rehabilitative settings, dynamic strength capacity has been determined via the one-repetition maximum (1RM) testing for decades. Because the literature concerned several limitations, such as injury risk and limited practical applicability in large populations (e.g., athletic training groups), the strength prediction via the velocity profile has received increasing attention recently. Referring to relative reliability coefficients and inappropriate interpretation of agreement statistics, several previous recommendations neglected systematic and random measurement bias.MethodsThis article explored the random measurement error arising from repeated testing (repeatability) and the agreement between two common sensors (vMaxPro and TENDO) within one repetition, using minimal velocity thresholds as well as the velocity = 0 m/s method. Furthermore, agreement analyses were applied to the estimated and measured 1RM in 25 young elite male soccer athletes.ResultsThe results reported repeatability values with an intraclass correlation coefficient (ICC) = 0.66–0.80, which was accompanied by mean absolute (percentage) errors (MAE and MAPE) of up to 0.04–0.22 m/s and ≤7.5%. Agreement between the two sensors within one repetition showed a systematic lower velocity for the vMaxPro device than the Tendo, with ICCs ranging from 0.28 to 0.88, which were accompanied by an MAE/MAPE of ≤0.13 m/s (11%). Almost all estimations systematically over/ underestimated the measured 1RM, with a random scattering between 4.12% and 71.6%, depending on the velocity threshold used.DiscussionIn agreement with most actual reviews, the presented results call for caution when using velocity profiles to estimate strength. Further approaches must be explored to minimize especially the random scattering.

Abstract Background Increases in maximal strength and muscle volume represent central aims of training interventions. Recent research suggested that the chronic application of stretch may be effective in inducing hypertrophy. The present systematic review therefore aimed to syntheisize the evidence on changes of strength and muscle volume following chronic static stretching. Methods Three data bases were sceened to conduct a systematic review with meta-analysis. Studies using randomized, controlled trials with longitudinal (≥ 2 weeks) design, investigating strength and muscle volume following static stretching in humans, were included. Study quality was rated by two examiners using the PEDro scale. Results A total of 42 studies with 1318 cumulative participants were identified. Meta-analyses using robust variance estimation showed small stretch-mediated maximal strength increases (d = 0.30 p

When improving athletic performance in sports with high-speed strength demands such as soccer, basketball, or track and field, the most common training method might be resistance training and plyometrics. Since a link between strength capacity and speed strength exists and recently published literature suggested chronic stretching routines may enhance maximum strength and hypertrophy, this review was performed to explore potential benefits on athletic performance. Based on current literature, a beneficial effect of static stretching on jumping and sprinting performance was hypothesized. A systematic literature search was conducted using PubMed, Web of Science and Google scholar. In general, 14 studies revealed 29 effect sizes (ES) (20 for jumping, nine for sprinting). Subgroup analyses for jump performance were conducted for short- long- and no stretch shortening cycle trials. Qualitative evaluation was supplemented by performing a multilevel meta-analysis via R (Package: metafor). Significant positive results were documented in six out of 20 jump tests and in six out of nine sprint tests, while two studies reported negative adaptations. Quantitative data analyses indicated a positive but trivial magnitude of change on jumping performance (ES:0.16, p = 0.04), while all subgroup analyses did not support a positive effect (p = 0.09–0.44). No significant influence of static stretching on sprint performance was obtained (p = 0.08). Stretching does not seem to induce a sufficient stimulus to meaningfully enhance jumping and sprinting performance, which could possibly attributed to small weekly training volumes or lack of intensity.

This study aimed to investigate the correlation between the passive muscle stiffness of the pectoralis major muscle pars clavicularis (PMc) and shoulder extension range of motion (ROM) in both male and female participants. Thirty-nine (23 male/16 female) physically active and healthy participants volunteered in this study. After a standardized warm-up, the PMc stiffness was tested via shear wave elastography at a slightly stretched position (long muscle length) and in a non-stretched position (short muscle length). Additionally, a custom-made device and 3D motion capture assessed the active shoulder extension ROM. We found a significant moderate and negative relationship between shoulder extension ROM and PMc stiffness at long muscle length (rs = −0.33; p = 0.04) but not at short muscle length (r = −0.23; p = 0.17). Additionally, there was no significant difference between male and female participants in the correlation analyses at both elbow angles. The moderate correlation between PMc stiffness at a slightly stretched position and shoulder extension ROM suggests that additionally, other structures such as nerves/fascia stiffness or even stretch tolerance might be factors that can be related to shoulder extension ROM.

In ice hockey, speed strength is one of the major physical key performance indicators, which is significantly influenced by maximum strength. The objective of this study was to evaluate the age‑dependent relationship of off-ice maximum strength and vertical jump performance with on-ice linear sprint performance, considering age and performance level. Ninety-one male youth and adult professional ice hockey players (age: 19.3±5.49 years) were recruited and divided into four age groups: under 16, 18, 21 years old and professional elite players (Pro) (i.e., > 21 years). They were tested in maximal isometric strength, squat jump (loaded and unloaded), countermovement jump and on-ice sprint performance (15 m and 30 m linear sprint; 15 m flying linear sprint). Statistical analysis revealed that on-ice sprint performance correlated with isometric strength performance (r = |0.34|-|0.63|) and with off-ice jump performance (r = |0.61|-|0.77|) without an influence of age group or performance level. However, performance differed between age groups and performance level, the largest differences being found between the youngest age group (U16) and the Pro group (g = 0.966–3.281). The present study shows that maximum strength influences on-ice sprint performances in ice hockey players, as well as performance differences between age groups and professional players. Strength and jumping performance should therefore be included in regular performance testing in ice hockey. Since performance differences are observed for almost all strength and speed-strength performances of the youth teams to the Pros, training of these variables is strongly recommended to improve in the transition phase from junior to elite level.

ObjectiveStretching is performed with numerous purposes in multiple settings such as prevention, rehabilitation, fitness training and sports. Its patterns of use substantially depend on the education and beliefs of health care and exercise professionals as they represent the multiplicators recommending and prescribing interventions to clients, patients and athletes. This study investigated movement experts' knowledge about the scientific evidence on stretching effects.DesignSurvey study.ParticipantsA total of 117 exercise and health professionals (physiotherapists, sports scientists, coaches) attending a training convention in Austria (male: n = 44, female: n = 73, 36±11 years) completed a digital survey. With its 22 items, the questionnaire addressed the movement experts' awareness of the evidence on stretching effects regarding a variety of related topics selected based on the findings of topical systematic reviews.ResultsThe majority of the individuals (57-88%) assumed positive effects of stretching on recovery, prevention of muscle injury, range of motion, muscular imbalance and artery elasticity. No or adverse effects were mostly claimed on bone injury prevention, maximal/explosive strength, and delayed-onset muscle soreness. In only 10 of 22 items, participants' classifications were in accord with the scientific evidence.ConclusionsThe awareness of research findings on stretching effects among exercise and health professionals is alarmingly low. Future studies may hence be geared to improve implementation and science communication.

IntroductionBased on the assumption of maximal strength as a basic ability, several studies show a high influence of maximum strength on jumping performance in several sport athletes. However, there is a wide range of correlations from r = 0.17–0.9 between squat 1RM and jumping performance in different sports. Additionally, there are only a few studies investigating the influence of deadlift one repetition maximum (1RM) on jumping performance. Thus, this study aimed to investigate the correlations between 1RM in the deadlift on jumping performance using the countermovement jump height (CMJ) and squat jump height (SJ) considering different sports.Methods103 athletes with experience in the deadlift from soccer, basketball, American football, powerlifting as well as participants from different sports without any deadlift experience (control group) were included to this study.ResultsOverall statistics showed a significant moderate influence of deadlift 1RM (r = 0.301–0.472) on jumping performance. However, subgroup analysis showed no significant correlation between deadlift 1RM and jumping performance in control participants, while moderate correlations could be detected in powerlifters (r = 0.34–0.39), soccer players (r = 0.437–0.46), American football players (0.584–0.62) and high correlations in basketball players (r = 0.809–0.848) showing significant influence of type of sport on correlations between deadlift maximum strength and jumping performance.DiscussionPresented results underline movement velocity- and task specificity of strength training routines which is discussed in the light of the respective sports.

Purpose: Stretch-induced force deficit suggests an acute stretch-specific strength capacity loss, which is commonly attributed to EMG reductions. Since those deficits could also be attributed to general fatigue induced by overloading the muscle, this study aimed to compare stretching with an exhausting calf raise programme to compare strength and stretching responses. Method: This study included 16 participants with different, high-duration calf muscle stretching effects (10, 20, 30 min of stretching) with resistance training (RT) (3 × 12 repetitions) performed until muscle failure, by using a cross-over study design with pre-post comparisons. Strength was tested via isometric plantar flexor diagnostics, while flexibility was assessed using the knee-to-wall test (KtW) and an isolated goniometer test. Results: Using a three-way ANOVA, RT strength decreases were greater compared to 10 and 20 min of stretching (p = 0.01–0.02), but similar to those of 30 min of stretching. ROM in the KtW showed no specific stretch-induced increases, while only the stretching conditions enhanced isolated tested ROM (p < 0.001–0.008). No RT-related isolated ROM increases were observed. Conclusions: The results showed both interventions had similar effects on strength and ROM in the calf muscles. More holistic explanatory approaches such as fatigue and warm-up are discussed in the manuscript and call for further research.

Purpose: While there is reported superior effectiveness with supervised training, it usually requires specialized exercise facilities and instructors. It is reported in the literature that high-volume stretching improves pectoralis muscles strength under supervised conditions while practical relevance is discussed. Therefore, the study objective was to compare the effects of volume equated, supervised- and self-administered home-based stretching on strength performance. Methods: Sixty-three recreational participants were equally assigned to either a supervised static stretching, home-based stretching, or control group. The effects of 15 min pectoralis stretching, 4 days per week for 8 weeks, were assessed on dynamic and isometric bench press strength and force development. Results: While there was a large magnitude maximal strength increase (p < 0.001–0.023, ƞ2 = 0.118–0.351), force development remained unaffected. Dynamic maximal strength in both groups demonstrated large magnitude increases compared to the control group (p < 0.001–0.001, d = 1.227–0.905). No differences between the intervention group for maximal strength (p = 0.518–0.821, d = 0.101–0.322) could be detected. Conclusions: The results could potentially be attributed to stretch-induced tension (mechanical overload) with subsequent anabolic adaptations, and alternative explanatory approaches are discussed. Nevertheless, home-based stretching seems a practical alternative to supervised training with potential meaningful applications in different settings.

PurposeStatic stretch training (SST) with long stretching durations seems to be sufficient to increase flexibility, maximum strength (MSt) and muscle thickness (MTh). However, changes in contraction properties and effects on muscle damage remain unclear. Consequently, the objective of the study was to investigate the effects of a 6-week self-performed SST on MSt, MTh, contractile properties, flexibility, and acute response of creatine kinase (CK) 3 days after SST.MethodsForty-four participants were divided into a control (CG, n = 22) and an intervention group (IG, n = 22), who performed a daily SST for 5 min for the lower limb muscle group. While isometric MSt was measured in leg press, MTh was examined via sonography and flexibility by functional tests. Muscle stiffness and contraction time were measured by tensiomyography on the rectus femoris. Additionally, capillary blood samples were taken in the pretest and in the first 3 days after starting SST to measure CK.ResultsA significant increase was found for MSt (p 0.310). Scheffé post hoc test did not show significant differences between the rectus femoris muscle inter- and intragroup comparisons for MTh nor for muscle stiffness and contraction time (p > 0.05, η2 0.05, η2 = 0.032.DiscussionIn conclusion, the increase in MSt cannot be exclusively explained by muscular hypertrophy or the increased CK-related repair mechanism after acute stretching. Rather, neuronal adaptations have to be considered. Furthermore, daily 5-min SST over 6 weeks does not seem sufficient to change muscle stiffness or contraction time. Increases in flexibility tests could be attributed to a stretch-induced change in the muscle–tendon complex.

Introduction: Speed-strength performance is important during human movements such as jumping, sprinting, and change of direction (COD) tasks, which are a substantial part of sports practice. Sex and age seem to influence performance output in young persons; however, few studies have focused on the influence of sex and age measured via standard protocols of performance diagnostics.Method: Therefore, the aim of this study was to investigate the influence of age and sex on linear sprint (LS), COD sprint, countermovement jump (CMJ) height, squat-jump (SJ) height, and drop-jump (DJ) height performance in untrained children and adolescents via a cross-sectional analysis. This study comprised 141 untrained male and female participants 10–14 years of age.Results: The results showed the influence of age in male participants on speed-strength performance, while in female participants, age did not significantly influence performance parameters. Moderate to high correlations between sprint and jump performance (r = 0.69–0.72), sprint and COD sprint performance (r = 0.58–0.72), and jump and COD sprint performance (r = 0.56–0.58) were found.Discussion: Based on the data from this study, it appears that the growth phase of age 10–14 does not necessarily lead to improvements in athletic performance. To ensure holistic motor development, female subjects in particular should be provided with specific training interventions with a focus on strength and power.

Measuring maximal strength (MSt) is a very common performance diagnoses, especially in elite and competitive sports. The most popular procedure in test batteries is to test the one repetition maximum (1RM). Since testing maximum dynamic strength is very time consuming, it often suggested to use isometric testing conditions instead. This suggestion is based on the assumption that the high Pearson correlation coefficients of r ≥ 0.7 between isometric and dynamic conditions indicate that both tests would provide similar measures of MSt. However, calculating r provides information about the relationship between two parameters, but does not provide any statement about the agreement or concordance of two testing procedures. Hence, to assess replaceability, the concordance correlation coefficient (ρc) and the Bland-Altman analysis including the mean absolute error (MAE) and the mean absolute percentage error (MAPE) seem to be more appropriate. Therefore, an exemplary model based on r = 0.55 showed ρc = 0.53, A MAE of 413.58 N and a MAPE = 23.6% with a range of −1,000–800 N within 95% Confidence interval (95%CI), while r = 0.7 and 0.92 showed ρc = 0.68 with a MAE = 304.51N/MAPE = 17.4% with a range of −750 N–600 N within a 95% CI and ρc = 0.9 with a MAE = 139.99/MAPE = 7.1% with a range of −200–450 N within a 95% CI, respectively. This model illustrates the limited validity of correlation coefficients to evaluate the replaceability of two testing procedures. Interpretation and classification of ρc, MAE and MAPE seem to depend on expected changes of the measured parameter. A MAPE of about 17% between two testing procedures can be assumed to be intolerably high.

Introduction: If the aim is to increase maximal strength (MSt) and muscle mass, resistance training (RT) is primarily used to achieve these outcomes. However, research indicates that long-duration stretching sessions of up to 2 h per day can also provide sufficient stimuli to induce muscle growth. In RT literature, sex-related differences in adaptations are widely discussed, however, there is a lack of evidence addressing the sex-related effects on MSt and muscle thickness (MTh) of longer duration stretch training. Therefore, this study aimed to investigate the effects of 6 weeks of daily (1 h) unilateral static stretch training of the plantar flexors using a calf-muscle stretching device.Methods: Fifty-five healthy (m = 28, f = 27), active participants joined the study. MSt and range of motion (ROM) were measured with extended and flexed knee joint, and MTh was investigated in the medial and lateral heads of the gastrocnemius.Results: Statistically significant increases in MSt of 6%–15% (p < .001–.049, d = 0.45–1.09), ROM of 6%–21% (p < .001–.037, d = 0.47–1.38) and MTh of 4%–14% (p < .001–.005, d = 0.46–0.72) from pre-to post-test were observed, considering both sexes and both legs. Furthermore, there was a significant higher increase in MSt, MTh and ROM in male participants. In both groups, participants showed more pronounced adaptations in MSt and ROM with an extended knee joint as well as MTh in the medial head of the gastrocnemius (p < .001–.047). Results for relative MSt increases showed a similar result (p < .001–.036, d = 0.48–1.03).Discussion: Results are in accordance with previous studies pointing out significant increases of MSt, MTh and ROM due to long duration static stretch training. Both sexes showed significant increases in listed parameters however, male participants showed superior increases.

Background: In animal studies long-term stretching interventions up to several hours per day have shown large increases in muscle mass as well as maximal strength. The aim of this study was to investigate the effects of a long-term stretching on maximal strength, muscle cross sectional area (MCSA) and range of motion (ROM) in humans.Methods: 52 subjects were divided into an Intervention group (IG, n = 27) and a control group (CG, n = 25). IG stretched the plantar flexors for one hour per day for six weeks using an orthosis. Stretching was performed on one leg only to investigate the contralateral force transfer. Maximal isometric strength (MIS) and 1RM were both measured in extended knee joint. Furthermore, we investigated the MCSA of IG in the lateral head of the gastrocnemius (LG) using sonography. Additionally, ROM in the upper ankle was investigated via the functional “knee to wall stretch” test (KtW) and a goniometer device on the orthosis. A two-way ANOVA was performed in data analysis, using the Scheffé Test as post-hoc test.Results: There were high time-effects (p = 0.003, ƞ² = 0.090) and high interaction-effect (p < 0.001, ƞ²=0.387) for MIS and also high time-effects (p < 0.001, ƞ²=0.193) and interaction-effects (p < 0.001, ƞ²=0,362) for 1RM testing. Furthermore, we measured a significant increase of 15.2% in MCSA of LG with high time-effect (p < 0.001, ƞ²=0.545) and high interaction-effect (p=0.015, ƞ²=0.406). In ROM we found in both tests significant increases up to 27.3% with moderate time-effect (p < 0.001, ƞ²=0.129) and high interaction-effect (p < 0.001, ƞ²=0.199). Additionally, we measured significant contralateral force transfers in maximal strength tests of 11.4% (p < 0.001) in 1RM test and 1.4% (p=0.462) in MIS test. Overall, there we no significant effects in control situations for any parameter (CG and non-intervened leg of IG).Discussion: We hypothesize stretching-induced muscle damage comparable to effects of mechanical load of strength training, that led to hypertrophy and thus to an increase in maximal strength. Increases in ROM could be attributed to longitudinal hypertrophy effects, e.g., increase in serial sarcomeres. Measured cross-education effects could be explained by central neural adaptations due to stimulation of the stretched muscles.

Speed strength performances are substantially dependent on maximum strength. Due to their importance, various methods have been utilized to measure maximum strength (e.g., isometric or dynamic) with discussed differences regarding transferability to sport-specific movements dependent upon the testing procedure. The aim of this study was to analyze whether maximum isometric force (MIF) during isometric back squats correlates with maximum strength measurements of the one repetition maximum (1RM) in the squat, with countermovement jump (CMJ) performance, and with drop jump (DJ) performances in elite youth soccer players (n = 16, 18.4 ± 1.5 [range: 17–23] years old). Additionally, concordance correlation coefficients (CCC, [ρc]) between isometric and dynamic measurements were calculated to verify whether one measurement can actually reproduce the results of the other. To improve comprehension, differences between isometric and dynamic testing values were illustrated by providing differences between both testing conditions. For this, the mean absolute error (MAE) and the mean absolute percentage error (MAPE) were calculated. To reach equality in scale, the 1RM measures were multiplicated by 9.81 to obtain a value of N. The 1RM demonstrated correlations of τ = |0.38| to |0.52| with SJ and CMJ performances, while MIF demonstrated correlations of τ = |0.21| to |0.32|. However, the correlations of both 1RM and MIF with the DJ reactive strength index (RSI = jump height/contact time) from different falling heights were of no statistical significance. The data showed significant correlations between both the absolute (τ = |0.54|) and the relative (τ = |0.40|) performances of 1RM and MIF, which were confirmed by CCC of ρc= |0.56| to |0.66|, respectively. Furthermore, the MAE and MAPE showed values of 2080.87 N and 67.4%, respectively. The data in this study show that, despite good correlations, there is no exact coincidence between isometric and dynamic strength measurements. Accordingly, both measurements may only represent an estimation of maximal strength capacity and cannot be substituted for each other. Therefore, maximal strength should be tested by using high similarity in the contraction condition, as it is used in the training process to counteract underestimation in strength because of unfamiliarity with the testing condition.