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A randomized trial of preexercise stretching for prevention of lower-limb injury
Abstract
This study investigated the effect of muscle stretching during warm-up on the risk of exercise-related injury.
1538 male army recruits were randomly allocated to stretch or control groups. During the ensuing 12 wk of training, both groups performed active warm-up exercises before physical training sessions. In addition, the stretch group performed one 20-s static stretch under supervision for each of six major leg muscle groups during every warm-up. The control group did not stretch.
333 lower-limb injuries were recorded during the training period, including 214 soft-tissue injuries. There were 158 injuries in the stretch group and 175 in the control group. There was no significant effect of preexercise stretching on all-injuries risk (hazard ratio [HR] = 0.95, 95% CI 0.77-1.18), soft-tissue injury risk (HR = 0.83, 95% CI 0.63-1.09), or bone injury risk (HR = 1.22, 95% CI 0.86-1.76). Fitness (20-m progressive shuttle run test score), age, and enlistment date all significantly predicted injury risk (P < 0.01 for each), but height, weight, and body mass index did not.
A typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits. Fitness may be an important, modifiable risk factor.
... As summarized in Table 2, we used the RoB 2.0 tool to assess risk of bias for each included study. The overall risk of bias was rated as low for 2 investigations (11,12), moderate for 7 studies Prevention of Lower Extremity Injuries in Tactical Populations (2022) 00:00 (9,24,49,55,56,76,79), and high for the remaining 9 studies (22,35,40,46,57,58,75,85,86). Seven reports had low risk attributes and one moderate risk item (9,11,12,49,55,79,80). ...
... Seven reports had low risk attributes and one moderate risk item (9,11,12,49,55,79,80). Seven reports had multiple low and moderate risk attributes (24,46,56,58,63,75,76,86). One report displayed a moderate risk for all domains (23), another was rated as high risk for randomization allocation and deviation from intended interventions (22), and a third was considered high risk for reported outcome result and randomization (35). ...
... Physical Training. Eight studies incorporated a physical training program (9,11,12,35,40,75,76,85); the majority did not reduce LEMSI occurrence (Table 3). One investigation compared a lower extremity strengthening and core stabilization exercise program to an active warm-up condition with further stratification based on expert (clinical administrators) vs. nonexpert (platoon leader) supervision (11). ...
Sinnott, AM, Krajewski, KT, LaGoy, AD, Beckner, ME, Proessl, F, Canino, MC, Nindl, BC, Turner, RL, Lovalekar, MT, Connaboy, C, and Flanagan, SD. Prevention of lower extremity musculoskeletal injuries in tactical and first responder populations: A systematic review and meta-analysis of randomized trials from 1955 to 2020. J Strength Cond Res XX(X): 000-000, 2022-Lower extremity musculoskeletal injuries (LEMSIs) impose a significant burden on tactical and first responder populations. To determine the effectiveness of LEMSI prevention strategies, we performed a systematic review and meta-analysis of randomized controlled trials published in English from 1955 to 2020 (PROSPERO: CRD42018081799). MEDLINE, EMBASE, Cochrane, CINAHL, ProQuest, and DTIC databases were searched for trials that assigned military service members, police, firefighters, or paramedics to LEMSI prevention interventions with a minimum surveillance period of 12 weeks. Evidence was synthesized as odds ratios (OR) for LEMSI occurrence between individuals assigned to interventions and those assigned to standard activities. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0. Random-effects meta-analyses were conducted for (a) physical training and (b) footwear modifications to reduce LEMSI and (c) footwear modifications to reduce stress fractures specifically. Certainty in the body of evidence was determined with the GRADE approach. Of 28,499 records, 18 trials comprised of more than 11,000 subjects were synthesized. Interventions included physical training (8, N = 6,838), footwear modifications (8, N = 3,792), nutritional supplementation (1, N = 324), and training modifications (1, N = 350). Overall risk of bias was generally moderate (N = 7 of 18) or high (N = 9 of 18). Physical training (OR = 0.87, 95% CI [0.71, 1.08], p = 0.22, I2 = 58.4%) and footwear modification (OR = 1.13, 95% CI [0.85, 1.49], p = 0.42, I2 = 0.0%) did not reduce LEMSI or stress fractures (OR = 0.76, 95% CI [0.45, 1.28], p = 0.30, I2 = 70.7%). Our results indicate that there is weak evidence to support current LEMSI prevention strategies. Future efforts will benefit from longer surveillance periods, assessment of women and nonmilitary populations, improved methodological rigor, and a greater breadth of approaches.
... [20][21][22] Initially, stretching effects were investigated, but without significant results. 22 23 Subsequently, a new review investigated the effects of neuromuscular training (NMT) on the incidence of injuries in athletes and military personnel. 20 Despite the results suggesting a protective effect by NMT, only two studies with military personnel were included, with contradictory results. ...
... The included studies were categorised by the type of injury prevention programme used (Table 1): combined exercises (n=8), stretching (n=4), NMT (n=4) and agility exercises (n=1). The samples were composed of soldiers, 24 28 31 recruits, 23 ...
... In other words, the injury incidence in the intervention group is the same as in the CG that performed only 46 and three had some concerns. 23 31 48 The main sources of biases were: bias arising from the randomisation process and the measurement of the outcome (Figure 4). Using the GRADE instrument, the overall quality of evidence was very low ( Table 2). ...
Introduction:
Exercise programmes have been used to prevent injuries in military personnel, as they can reduce modifiable risk factors for injuries. Our aim was to review the literature to evaluate the effects of different exercise protocols on the prevention of injuries in military personnel.
Methods:
A systematic literature review examined the effects of different exercise protocols on the prevention of musculoskeletal injuries in the military. Several databases were explored to find experimental studies that investigated the effects of prevention programmes on the risk of injury. We have extracted from the studies: profile of participants, sample size, study design and characteristics of the control group (CG), the type of intervention and the relative risk (RR) in the experimental group and CG, with their significance levels. For data analysis, we used the RevMan V.5.3 software. The measure of RR was investigated. The risk of publication bias was analysed with Begg's test.
Results:
A total of 13 694 titles and studies were recovered from the databases and by manual search. After the removal of duplicate titles and studies that did not meet the eligibility criteria, 17 studies were selected. The protocols were composed of neuromuscular training, stretching, agility training or combined exercises. The meta-analysis showed that injury prevention exercise programmes reduced the risk of musculoskeletal injuries in military personnel by 14% (RR=0.86; 95% CI=0.76 to 0.98).
Conclusion:
Injury prevention exercise programmes promoted a slight reduction in the risk of musculoskeletal injuries in military personnel.
Level of evidence:
Very low.
Trial registration number:
CRD 42017077946.
... Thirteen RCTs involving a total of eight thousand two hundred and ten individuals (mostly military recruits and young athletes) were included in this review ( figure 1 and table 1). [25][26][27][28][29][30][31][32][33][34][35][36][37] The mean age of participants in the individual trials ranged from 13 to 39 years. The most common interventions evaluated were multicomponent exercise (n=4), foot orthoses (n=4) and patellofemoral braces (n=2), with single trials evaluating the effect of: (1) stretching; (2) two approaches to increase exercise dose in a running programme and (3) a running technique retraining programme. ...
... Single studies evaluating the effect of a passive stretching intervention compared with no stretching (1538 participants, very low level of evidence), 35 nor a running programme that progressed intensity (compared with volume) (447 participants, low level of evidence) 36 had a statistically significant influence on patellofemoral pain risk (figure 2). ...
... [48][49][50] It is unlikely that the static stretching component of the multifaceted exercise programmes contributed substantially to the observed patellofemoral pain risk reduction as the single study included in this review evaluating static muscle stretching (3-4 times per week vs no stretching, in a military population) observed no significantly reduced risk of patellofemoral pain. 35 Although the level of evidence for this finding from static stretching was very low, it is consistent with a previous systematic review concluding that static stretches do not effectively reduce soft tissue running-related injuries. 39 Future studies should deliver sufficient doses of strength training to achieve and maximise preventative effects. ...
Objective
To evaluate the effectiveness of interventions to reduce the risk of incident patellofemoral pain.
Design
Systematic review and meta-analysis, with strength of evidence evaluated separately for each intervention type.
Data sources
MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus.
Eligibility criteria for selecting studies
Randomised controlled trials evaluating the effectiveness of interventions to reduce patellofemoral pain risk compared with a control/non-exposed group.
Results
Thirteen trials of mostly military recruits and young athletes analysed six different interventions. There was low certainty evidence from two trials (227 participants) that patellofemoral braces worn during physical activity (compared with no brace) effectively reduced the risk of patellofemoral pain (risk ratio (RR) 0.40, 95% CI 0.22 to 0.73; I ² =24.0%). There was low certainty evidence from one trial (320 participants) that running technique retraining to (run softer) reduced patellofemoral pain risk (RR 0.21, 95% CI 0.07 to 0.60). There was low certainty evidence from four trials (3364 participants) that multicomponent (strengthening/neuromuscular) exercise programmes did not significantly reduce the risk of patellofemoral pain (RR 0.49, 95% CI 0.18 to 1.36; I ² =64.9%), although broad CIs may reflect exercise dose variations among studies. There was very low certainty evidence from four trials (2314 participants) that foot orthoses (compared with flat inserts/no orthosis) did not significantly reduce the risk of patellofemoral pain (RR 0.63, 95% CI 0.35 to 1.13; I ² =0.0%). Static stretching and a running programme that progressed intensity (compared with volume) did not significantly influence patellofemoral pain risk (single studies).
Conclusion
There is low-level evidence that patellofemoral braces and running technique retraining can reduce the risk of patellofemoral pain by 60%–79%.
... Stretching is commonly used by athletes as a part of their conventional warm-up routine, specially in sports requiring the ability to move comfortably through a large range of motion (ROM) (Sands, Caine, & Borms, 2003). Among all stretching techniques, static stretching (SS) has been the most common technique used in warm-up routines, however it has been criticised for impairing muscular performance (i.e. ...
... muscle power, sprint time and jump height) (Behm & Chaouachi, 2011). Therefore, more oriented dynamic techniques are recommended before activity for tissue health and performance improvement (Behm & Chaouachi, 2011;Schleip & Müller, 2013). ...
... 88 Science of Gymnastics Journal Maganaris, & Narici, 2016;Freitas, Andrade, Larcoupaille, Mil-homens, & Nordez, 2015;Simpson, Kim, Bourcet, Jones, & Jakobi, 2017). Although the effects of SS on ROM in various joints are widely scientifically supported, its effects on injury prevention (Pope, Herbert, Kirwan, & Graham, 2000;Small, Mc Naughton, & Matthews, 2008;Thacker, Gilchrist, Stroup, & Kimsey Jr, 2004;Weldon & Hill, 2003) and improvement of physical performance have been questioned. ...
The aim of this study was to determine the long term effect of dynamic range of motion (DROM) stretching technique and static stretching (SS) on hip range of motion (ROM), hip isometric strength and vertical jump performance in female gymnasts. In a randomized controlled trial eighteen gymnasts (age 13 ± 2 years) were assigned to a DROM group (n= 9) or SS group (n=9). Participants were assessed at baseline and again at completion of the intervention on: hip extensión (HE), hip flexion (HF), 1RM isometric HF strength, squat jump (SJ) and split leap (SL). Results: DROM group improved statistically from pre-to post-test in right leg HE ROM (13.67 4.7 vs. 21.22 5.2), right leg HF ROM (129.9 9.9 vs. 139.0 10.4), hip isometric strength for the right leg (2.0 1.1 vs. 4.7 1.6) and the left leg (1.7 0.7 vs. 4.1 1.6). Jump performance was not affected by type of stretching. Significance was set at 0.05 (2-tailed) for all analyses. DROM was more effective in improving gymnastic performance variables than SS. Such information may assist in determining the applications of various stretching techniques in flexibility-trained female athletes.
... Such effects may be perceived as having a positive impact on the reduction of injury prevalence, since common actions within Rugby League feature rapid dynamic lengthening of muscle groups through their full range of motion (16,33,34,38). However, research has revealed that static stretching prior to performance does not reduce the risk of injury in comparison to dynamic warm-up protocols (1,31,38). ...
... This notion is further supported by focus group responses. However, research indicates that static stretching prior to performance does not reduce injury prevalence, despite positive effects on range of motion (1,13,19,31,41). Even though 'Injury prevention' was the most popular chosen predominant benefit from the questionnaire responses, the focus groups highlighted that all four themes within the 'Perceived benefits of warm-up' dimension were each perceived to offer benefit by several players. ...
This study aimed to assess warm-up practices within professional and amateur Rugby League players, specifically to determine players’ perceptions why particular methods were used and discover whether any differences existed in warm-up practices and perceptions between the two separate standards. The study used a 10-question online questionnaire to investigate 30 professional and 53 amateur players warm-up protocols and their perceptions behind their practices. To provide a richer understanding regarding the practices and perceptions surrounding warm-up protocols, the questionnaire was followed by two focus groups (professionals and amateurs), which included four participants in each. Following analysis of the questionnaire responses, it was discovered that professional players’ warm-up protocols were significantly longer in duration than amateur players (P = 0.009). However, for all other variables assessed including; specific warm-up protocols, static stretch duration, and perceptions and beliefs concerning warm-up protocols, there were no significant differences between professionals and amateurs. Overall findings demonstrated the widespread use of static stretching within warm-up for both professionals and amateurs; 71 of 83 players (86%) reported usage. It was also highlighted that injury prevention was the most commonly perceived benefit from performing a warm-up across both standards [(Professional; 15 of 30, 50%) (Amateur; 27 of 53, 51%)]. Findings from the focus group generally supported questionnaire responses, and it was identified that the warm-up practices and protocols of Rugby League players were influenced by others such as coaches and strength and conditioning coaches which emphasises the importance of the role of these practitioners.
... It has been suggested that stretching exercises increase muscle flexibility, joint range of motion, prevent muscle stiffness, and contribute positively to proprioception by increasing the excitability of mechanoreceptors in the muscle with the elongation they cause (Ghaffarinejad et al., 2007;Larsen et al., 2005;Pope et al., 2000). On the other hand, it has been suggested that stretching exercises may negatively affect proprioception (Avela et al., 1999;Björklund et al., 2006;Torres et al., 2012). ...
Amaç: Germe egzersizi rehabilitasyonda sıklıkla kullanılmaktadır. Bununla birlikte germe egzersizleri kas reseptörlerini ve ilgili eklem propriosepsiyonunu etkileyebilir. Amacımız hamstring kaslarına üç farklı şiddette uygulanan statik germe egzersizlerinin (SGE) diz propriosepsiyonu (DP) üzerine olan akut etkilerini karşılaştırmaktır. Yöntem: Araştırmaya 18-45 yaş aralığında 108 sağlıklı yetişkin (103 Erkek, 5 Kadın) dahil edilmiştir. Çalışmaya dahil edilen katılımcılar randomize olarak 3 gruba ayrıldı. Gruplara farklı germe şiddetleri ile (maksimum germe şiddetinin %50’si, %75’i ve %100’ü), 30 saniye süreli SGE uygulandı. SGE dominant taraftaki hamstring kasına 3 tekrarlı olarak gerçekleştirildi. Grupların germeden önce ve hemen sonra 20 ve 45 derecelik fleksiyon pozisyonunda DP değerlendirildi. Bulgular: : Farklı şiddetteki SGE öncesi ve sonrası 20 ve 45 derecelik diz fleksiyonundaki propriosepsiyon ölçümlerinin hem grup içi değerleri hem de gruplar arası karşılaştırma sonuçları arasında anlamlı fark bulunmadı (p>0.05). Sonuç ve Öneriler: Farklı şiddetlerde uygulanan SGE’nin DP üzerine etkisi olmadığı saptandı. Bu araştırmada üç farklı tip germe şiddeti sonrası akut etki değerlendirilmiş olup farklı süre ve tekrar sayısındaki germe uygulamalarının akut ve kronik etkinliğinin irdelenmesine ihtiyaç vardır.
... However, some researchers have concluded that stretching has no effect on injury prevention (Herbert & Gabriel, 2002;Pope, Herbert, Kirwan, & Graham, 2000;Small, Mc Naughton, & Matthews, 2008). ...
Traditional warm-up in sport contents the stretching. The stretching effects are a frequent subject of research in physical education, but the results are conflicting. The aim of current study is to check how acute stretching (static and dynamic) influences to the strength of hamstring and quadriceps, as well as their mutual ratio. These variables were monitored at different velocities of contraction (60 and 240˚/s). On the sample of 10 students in good health, modern isokinetic diagnostics (4000 Hz the sampling rate) was applied. Higher strength values in both muscle groups were measured during slow contraction, while HRQ values were higher during fast contractions. The results show that the muscle strength of hamstring and quadriceps can be increased by applying acute stretching (p < 0.05), but at the same time the HQR does not change significantly (p > 0.05). The same conclusions were drawn for both low and high contraction velocities.
... However, this was a very small study (n = 22), and the generalization of the effectiveness of such an exercise program is limited. A study of 1538 soldiers found that a 12-week stretching program during warm-up work did not reduce the risk of injury to soldiers; however, they found that the soldiers' physical fitness itself was a statistically significant predictor of risk of lower limb injury [115]. In another cohort of soldiers, performing RE at least three times a week was associated with a 54% lower risk of running-related injuries compared to performing no or less than one unit of RE per week (p < 0.001) [116]. ...
It is well-accepted that at least a certain amount of resistance exercise (RE) is recommended for most endurance athletes. In this review, we aim to summarize the evidence regarding the effects of RE on running economy, running biomechanics, and running-related injury risk in endurance runners. The evidence robustly shows that lower limb RE is effective for improving running economy and performance, with a combination of strength and plyometric training being recommended to improve RE. Isometric training is also emerging as a possible alternative to implement during periods of high overall training load. Lower limb RE may change some aspects of joint kinematics during running; however, the evidence regarding the effects on kinetics is limited. Lower limb RE may help reduce running-related injury risk, but further evidence is needed.
... Other systematic reviews have failed to find an association between stretching and injury risk (Herbert and Gabriel, 2002;Weldon and Hill, 2003;Thacker et al., 2004;Small et al., 2008;Lauersen et al., 2014;Leppänen et al., 2014;Lewis, 2014;Dijksma et al., 2020). Based on one of the largest RCT with military individuals (Pope et al., 2000), a total of 337 individuals would need to undergo a stretching intervention to prevent a single lower-limb injury. The argument that stretching does not reduce overall risk of injury but might reduce risk of musculoskeletal injury (Reid et al., 2018) should consider a trade-off: if overall risk is the same but risk of musculoskeletal injury is reduced, other risks were possibly aggravated. ...
... As pesquisas vêm mostrando, de forma sistemática, que alongar não previne lesões (Behm et al., 2015;Harvey et al., 2017;Herbert & Gabriel, 2002;Hori, Hasegawa, & Takasaki, In press;Lauersen, Bertelsen, & Andersen, 2014;Nuzzo, 2020;O'Connor et al., 2019;Pope, Herbert, Kirwan, & Graham, 2000). Existem, porém, alguns estudos associativos (ou seja, associam duas coisas, mas não permitem saber relações de causa de efeito), mostrando uma relação entre risco de lesão e flexibilidade (De La Motte, Lisman, Gribbin, Murphy, & Deuster, 2019). ...
... There is no evidence that flexibility training can reduce hamstring strains 53 . Only one study on military basic trainee indicates that such flexibility training can reduce the number of lower limb overuse injuries 114 while another military-based study also found that there is no effect 115 . It may be because hamstring strains occur during maximal sprinting where hamstrings are not stretched towards their limit 53 . ...
Hamstring strain injury is the most common muscle injury in football and comes with a high reinjury rate. Various injury prevention programmes have been developed, yet most solely focus on the hamstring injury prevention part and neglect the need for performance enhancement, which might decrease the efficiency and compliance of the training sessions. The purpose of this study was to determine if a 12-week neuromuscular sprint training programme is effective in reducing hamstring strain injury risk and improving playing performance. The programme consisted of repeated short sprint training and neuromuscular training that focused on developing correct sprinting movement patterns and strengthening hamstring muscles. Twenty-two adolescent male football players participated in this study. After 12 weeks of training, subjects showed a significant improvement in isokinetic hamstring muscles concentric strength 60°s-1 and 240°s-1 by an average of 24.89% and 31.48% (p<0.001) respectively. H:Q ratio at both parameters increased by 22.45% and 48.42% respectively (p>0.001). Regarding the playing performance, the time for 30-m maximal speed running was significantly 3.14% shorter in the post-test (p<0.001). Countermovement jump height also increased significantly by 8.46% (p=0.006). In conclusion, this training programme seems to be effective in reducing hamstrings strain injury and enhancing playing performance.
... However, until now, usual interventions meant to work as protective factors for RRIs, such as warm-up, cool-down, graded training, and stretching exercises, lacked scientific evidence of effectiveness. 2,6,27,40 The recent application of a foot-core strengthening program that is simple to implement has shown success in reducing the RRI risk in middle-and long-distance recreational runners by 2.42-fold, 30 demonstrating that a ground-up approach is a promising strategy to prevent RRIs. The successful ground-up approach used in the mentioned intervention is based on the premise that the foot and ankle are complex structures with several tissues and mechanical properties that allow the foot to efficiently perform pivotal actions for dampening impacts and propelling the body forward during running. ...
Background:
Running carries the risk of several types of running-related injuries (RRIs), especially in the lower limbs. The variety of risk factors and the lack of strong evidence for several of these injury risks hinder the ability to draw assertive conclusions about them, hampering the implementation of effective preventive strategies. Because the etiology of RRIs seems to be multifactorial, the presence of RRI risk factors might influence the outcome of therapeutic strategies in different ways. Thus, further investigations on how risk and protective factors influence the incidence and prevention of RRIs should be conducted.
Purpose:
To investigate the predictive effect of well-known risk factors and 1 protective factor-foot-core training-on the incidence of lower limb RRIs in recreational runners.
Study design:
Cohort study; Level of evidence, 2.
Methods:
Middle- and long-distance recreational runners (N = 118) were assessed at baseline and randomly allocated to either an intervention group (n = 57) or a control group (n = 61). The intervention group underwent an 8-week (3 times/wk) foot-core training program. Participants were followed for a year after baseline assessment for the occurrence of RRIs. Logistic regression with backward elimination of variables was used to develop a model for prediction of RRI in recreational runners. Candidate predictor variables included age, sex, body mass index, years of running practice, number of races, training volume, training frequency, previous RRI, and the foot-core exercise training.
Results:
The final logistic regression model included 3 variables. As previously shown, the foot-core exercise program is a protective factor for RRIs (odds ratio, 0.40; 95% CI, 0.15-0.98). In addition, older age (odds ratio, 1.07; 95% CI, 1.00-1.14) and higher training volume (odds ratio, 1.02; 95% CI, 1.00-1.03) were risk factors for RRIs.
Conclusion:
The foot-core training was identified as a protective effect against lower limb RRI, which can be negatively influenced by older age and higher weekly training volume. The predictive model showed that RRIs should be considered a multivariate entity owing to the interaction among several factors.
Registration:
NCT02306148 (ClinicalTrials.gov identifier).
... A subsequent study, in which recruits who were undertaking 12 weeks of basic training stretched each of 6 lower leg muscles before all physical training sessions (41), again did not reveal a clinically worthwhile reduction in allcause lower limb injury incidence (including lower body stress fractures, muscle strains, ligament sprains, periostitis, tendinopathy meniscal lesions, compartment syndromes, and bursitis, among others). Together, the studies by Pope et al. (39,41) indicate that, while intrinsic levels of flexibility (ROM) are associated with injury incidence, the imposition of stretch training programs may not influence overall injury rates, at least in military personnel who presumably perform many activities that would not be commonly performed during standard exercise or sports session. However, their data also indicate a lower incidence of thigh muscle strains (80%: 10 versus 2 injuries with stretch training group) and ankle joint injuries (30%: 27 versus 19 injuries in the stretch trained group) within the cohort. ...
Evidence for the effectiveness of acute and chronic stretching for improving range of motion is extensive. Improved flexibility can positively impact performances in activities of daily living and both physical and mental health. However, less is known about the effects of stretching on other aspects of health such as injury incidence and balance. The objective of this review is to examine the existing literature in these areas. The review highlights that both pre-exercise and chronic stretching can reduce musculotendinous injury incidence, particularly in running-based sports, which may be related to the increased force available at longer muscle lengths (altered force-length relationship) or reduced active musculotendinous stiffness, among other factors. Evidence regarding the acute effects of stretching on balance is equivocal. Longer-term stretch training can improve balance, which may contribute to a decreased incidence of falls and associated injuries and may thus be recommended as an important exercise modality in those with balance deficits. Hence, both acute and chronic stretching seem to have positive effects on injury incidence and balance, but optimum training plans are yet to be defined.
... Static stretching-which has long been a key facet of traditional warmups in many sports [1]-can lead to improvements in range of motion and have other performance benefits [2]. However, static stretching has not been shown to decrease injuries when completed on its own, and as a result it is increasingly recommended that warmup activities include "dynamic" components [2][3][4][5][6][7]. Dynamic, or "neuromuscular" warmup activities can be defined as neuromuscular training programs that incorporate general (e.g., fundamental movements) and specific (e.g., sport-specific movements) strength and conditioning activities such as resistance, dynamic stability, balance, core strength, plyometric, and agility exercises [8,9]. ...
Background
Neuromuscular warmups have gained increasing attention as a means of preventing sports-related injuries, but data on effectiveness in basketball are sparse. The objective of this systematic review was to evaluate evidence of the effectiveness of neuromuscular warmup-based strategies for preventing lower extremity injuries among basketball athletes.
Methods
PubMed and Cochrane Library databases were searched in February 2019. Studies were included if they were English-language randomized controlled, non-randomized comparative, or prospective cohort trials, tested neuromuscular and/or balance-focused warmup interventions among basketball players, and assessed at least one type of lower extremity injury as a primary outcome. Criteria developed by the USPSTF were used to appraise study quality, and GRADE was used to appraise the body of evidence for each outcome. Due to heterogeneity in the included studies, meta-analyses could not be performed.
Results
In total, 825 titles and abstracts were identified. Of the 13 studies which met inclusion criteria for this review, five were balance interventions (3 randomized controlled trials) and eight were multicomponent interventions involving multiple categories of dynamic neuromuscular warmup (5 randomized controlled trials). Authors of four of the studies were contacted to obtain outcome data specific to basketball athletes. Basketball specific results from the studies suggest significant protective effects for the following lower extremity injuries: ankle injuries (significant in 4 out of the 9 studies that assessed this outcome); ACL injuries (2 of 4 studies); knee injuries generally (1 of 5 studies); and overall lower extremity injuries (5 of 7 studies). All but one of the non-significant results were directionally favorable. Evidence was moderate for the effect of multicomponent interventions on lower extremity injuries generally. For all other outcomes, and for balance-based interventions, the quality of evidence was rated as low.
Conclusion
Overall, the evidence is supportive of neuromuscular warmups for lower extremity injury prevention among basketball players. However, most studies are underpowered, some used lower-quality research study designs, and outcome and exposure definitions varied. Due to the nature of the study designs, effects could not be attributed to specific intervention components. More research is needed to identify the most effective bundle of warmup activities.
... 4 As with most research on different modes of stretching, there is controversy about whether a stretching program will in fact reduce the incidence of injuries. 5 There are many stretching methods used that have demonstrated increased flexibility. Among the better known methods are: static, ballistic, dynamic, and proprioceptive neuromuscular facilitation (PNF). ...
Background: There is continued controversy related to flexibility gains from different stretching protocols and within single protocols. Stretching methods include static, ballistic, dynamic, and proprioceptive neuromuscular facilitation (PNF). A combination of stretching methods may be an improved way to increase active knee range of motion (ROM). This study evaluated a single program formulated with static and ballistic components. Objective: To compare active knee ROM following stretching programs which either included combined static and ballistic stretching (CSBS) or static stretching (SS) alone. It was hypothesized that CSBS would show a greater increase in active knee ROM than SS. Setting: The pre- and post- measurements were performed in a laboratory. Subjects were randomly assigned to either treatment group or a non-stretching control group and given written instructions on how to perform their designated protocol at home. Subjects: Forty-three (33M, 10F) healthy collegiate aged participants (24.0 + 3.69 yrs, 176.21 + 10.0 cm, 78.15 + 12.93 kg) with no history of injury to the lower extremity or low back for the previous 6 months were eligible to participate in the study. Interventions: Two treatment groups either performed SS or CSBS for 30 seconds on each leg, twice a day for 2 weeks. All subjects but 3 provided both legs, and each leg was evaluated separately, providing 83 total measurements. Main Outcome Measures: A Johnson Digital Inclinometer was used to measure active knee extension. A mixed ANOVA with a Tukey post hoc test was used for statistical analysis. Results: There was no statistically significant difference in active knee ROM between groups at the pre-test, F(2,80)=1.062, p=.351, partial ƞ2=.026 (SS: 52.56 + 7.50º, CSBS: 49.84 + 8.91⁰, control: 49.39 + 10.09⁰). There was a statistically significant difference in active knee ROM between groups at the post-test, F(2,80)=29.034, p .05). There was homogeneity of covariance’s, as assessed by Box's test of equality of covariance matrices (p = .076). There was homogeneity of variances, as assessed by Levene's test of homogeneity of variance (p>.05). Conclusions: SS and CSBS are equally effective for improving active knee ROM. A trend indicating CSBS showing only slightly greater differences may be due to limited time allowed to master the CSBS method, with no supervision during stretching sessions.
... Other systematic reviews have failed to find an association between stretching and injury risk (Herbert and Gabriel, 2002;Weldon and Hill, 2003;Thacker et al., 2004;Small et al., 2008;Lauersen et al., 2014;Leppänen et al., 2014;Lewis, 2014;Dijksma et al., 2020). Based on one of the largest RCT with military individuals (Pope et al., 2000), a total of 337 individuals would need to undergo a stretching intervention to prevent a single lower-limb injury. The argument that stretching does not reduce overall risk of injury but might reduce risk of musculoskeletal injury (Reid et al., 2018) should consider a trade-off: if overall risk is the same but risk of musculoskeletal injury is reduced, other risks were possibly aggravated. ...
Flexibility is the ability to move through full joint range of motion (ROM), while stretching is an intervention to improve flexibility and achieve other goals (e.g., post-exercise relaxation) (ACSM, 2021). Stretching has been promoted as mandatory in exercise programs (Behm, 2019; American Heart Association, 2020; ACSM, 2021), although this is changing toward an optional feature (Bull et al., 2020). There are different types of stretching, including active static stretching (SS—active lengthening of a muscle until the feeling of stretch or to the point of discomfort), passive static stretching (PS—where an external force is applied, e.g., by a coach or a colleague), dynamic stretching (DS –controlled movements through the joint ROM) and proprioceptive neuromuscular facilitation (PNF—combining PS with isometric contractions) (Behm, 2019). We will focus on SS and PS, since these methods are at the heart of most debates, with the pendulum swinging across the years (Behm et al., 2021b). The answer to “Can I perform a given exercise intervention?” is straightforward: when the benefits of an intervention outweigh its adverse effects or contra-indications, the answer is “yes.” Let us take the example of a study with 15 University students (Bengtsson et al., 2018), to illustrate the difference between the two questions: the negative acute effects of SS during a warm-up were restored if followed by isokinetic contractions, suggesting that SS can be included in a comprehensive warm-up protocol. University students are not representative of athletes, and a small sample does not warrant generalizations, but our point is that answering the first question (“Can I?”) does not answer the second question (“Do I have to?”). Focusing the research question and applicability on “Can I?” may be short-sighted. To date, we feel that research has focused more strongly on answering what stretching can do, while more information is required as to how stretching compares to alternative interventions. We will explore the differences between “Can I?” and “Do I have to?” stretch and their implications to warm-up, cool-down, ROM, and injury risk.
... Poor levels of fitness, both metabolic and musculoskeletal, have been associated with a higher risk of trainingrelated injuries and attrition (8,22,30,32,33,40,42,57,66,70,73,74). Pope et al. (73) found that the risk of attrition through failing to complete military training was approximately 25 times greater in trainees who scored poorly (bottom percentiles) on the 20-m progressive shuttle run test (PSRT) when compared to trainees who scored highly (upper percentiles). ...
... Other systematic reviews have failed to find an association between stretching and injury risk (Herbert and Gabriel, 2002;Weldon and Hill, 2003;Thacker et al., 2004;Small et al., 2008;Lauersen et al., 2014;Leppänen et al., 2014;Lewis, 2014;Dijksma et al., 2020). Based on one of the largest RCT with military individuals (Pope et al., 2000), a total of 337 individuals would need to undergo a stretching intervention to prevent a single lower-limb injury. The argument that stretching does not reduce overall risk of injury but might reduce risk of musculoskeletal injury (Reid et al., 2018) should consider a trade-off: if overall risk is the same but risk of musculoskeletal injury is reduced, other risks were possibly aggravated. ...
The effects and usefulness of active and passive static stretching have raised heated debates. Over the years, the pendulum has swung from a glorified vision to their vilification. As most of the times, the truth often lies somewhere in-between. But even if there was no controversy surrounding the effects of static and passive stretching (which there is), and even if their effects were homogeneously positive (which they are not), that would not be sufficient to make stretching mandatory for practicing physical exercise, for most populations. Amidst the many discussions, an important issue has remained underexplored: the prerequisites to answer the question “Can I?” are not sufficient to answer the question “Do I have to?”, especially when alternative interventions are available. In this current opinion paper, we address four potential applications of stretching: (i) warm-up; (ii) cool-down; (iii) range of motion; and (iv) injury risk. We argue that while stretching can be used in the warm-up and cool-down phases of the training, its inclusion is not mandatory, and its effectiveness is still questionable. Stretching can be used to improve range of motion, but alternative and effective interventions are available. The role of stretching in injury risk is also controversial, and the literature often misinterprets association with causation and assumes that stretching is the only intervention to improve flexibility and range of motion. Overall, the answer to the question “Can I stretch?” is “yes”. But the answer to the question “Do I have to?” is “no, not really”.
... However, some researchers have concluded that stretching has no effect on injury prevention (Herbert & Gabriel, 2002;Pope, Herbert, Kirwan, & Graham, 2000;Small, Mc Naughton, & Matthews, 2008). ...
Traditional warm-up in sport contents the stretching. The stretching effects are a frequent subject of research in physical education, but the results are conflicting. The aim of current study is to check how acute stretching (static and dynamic) influences to the strength of hamstring and quadriceps, as well as their mutual ratio. These variables were monitored at different velocities of contraction (60 and 240 ̊/s). On the sample of 10 students in good health, modern isokinetic diagnostics (4000 Hz the sampling rate) was applied. Higher strength values in both muscle groups were measured during slow contraction, while HRQ values were higher during fast contractions. The results show that the muscle strength of hamstring and quadriceps can be in-creased by applying acute stretching (p < 0.05), but at the same time the HQR does not change significantly (p > 0.05). The same conclusions were drawn for both low and high contraction velocities.
... 52 Common preventive actions, 45 such as warm-up, cool-down, and stretching exercises, lack scientific evidence of effectiveness. 40,41,53 Many studies have investigated conditions and behaviors that could be risk factors for RRIs. In a systematic review, Nielsen et al 38 reported that weekly running volume appeared to have an effect on rate of RRIs. ...
Background
Running-related injuries (RRIs) are a pervasive menace that can interrupt or end the participation of recreational runners in this healthy physical activity. To date, no satisfactory treatment has been developed to prevent RRIs.
Purpose
To investigate the efficacy of a novel foot core strengthening protocol based on a ground-up approach to reduce the incidence of RRIs in recreational long-distance runners over the course of a 1-year follow-up.
Study Design
Randomized controlled trial; Level of evidence, 1.
Methods
The participants, 118 runners, were assessed at baseline and randomly allocated to either an intervention group (n = 57) or a control group (n = 61). The intervention group received an 8-week training course focused on the foot-ankle muscles, followed by remotely supervised training thereafter. Assessments consisted of 3 separate biomechanical evaluations of foot strength and foot posture and a weekly report on each participant’s running distance, pace, and injury incidence over 12 months.
Results
The control group participants were 2.42 times (95% CI, 1.98-3.62) more likely to experience an RRI within the 12-month study period than participants in the intervention group ( P = .035). Time to injury was significantly correlated with Foot Posture Index ( P = .031; r = 0.41) and foot strength gain ( P = .044; r = 0.45) scores. This foot exercise program showed evidence of effective RRI risk reduction in recreational runners at 4 to 8 months of training.
Conclusion
Recreational runners randomized to the new foot core strengthening protocol had a 2.42-fold lower rate of RRIs compared with the control group. Further studies are recommended to better understand the underlying biomechanical mechanisms of injury, types of injuries, and subgroups of runners who might benefit maximally.
Registration
NCT02306148 (ClinicalTrials.gov identifier).
... [6][7][8][9][10][11][12] Of the 91 studies included, 5 studies were scored as level I evidence. [13][14][15][16][17] Forty-two studies were level II evidence. 1 3 4 9 11 18-54 Forty-two studies were level III, 2 5-8 10 12 54-89 and 2 studies were level IV. 90 91 While assessing study size, we found that 85 (93%) studies included over 120 subjects; 4 (4%) studies included between 40 and 120 subjects; and only 2 (3%) studies included fewer than 40 subjects. ...
Introduction
Musculoskeletal foot and ankle injuries are commonly experienced by soldiers during military training. We performed a systematic review to assess epidemiological patterns of foot and ankle injuries occurring during military training.
Methods
A review of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search, done on 14 February 2019, resulted in 1603 reports on PubMed, 565 on Embase and 3 on the Cochrane Library. After reading the remaining full-text articles, we included 91 studies.
Results
Among a population of 8 092 281 soldiers from 15 countries, 788 469 (9.74%) foot and ankle injuries were recorded. Among the 49 studies that reported on length of training, there were 36 770/295 040 (18.17%) injuries recorded among women and 248 660/1 501 672 (16.56%) injuries recorded among men over a pooled mean (±SD) training period of 4.51±2.34 months. Ankle injuries were roughly 7 times more common than foot injuries, and acute injuries were roughly 24 times more common than non-acute injuries. Our findings indicated that, during a 3-month training period, soldiers have a 3.14% chance of sustaining a foot and ankle injury. The incidence of foot or ankle injury during military parachutist training was 3.1 injuries per thousand jumps.
Conclusions
Our findings provide an overview of epidemiological patterns of foot and ankle injuries during military training. These data can be used to compare incidence rates of foot and ankle injuries due to acute or non-acute mechanisms during training. Cost-effective methods of preventing acute ankle injuries and non-acute foot injuries are needed to address this problem.
... An experimental study investigates the effects of muscle stretching during warm-up on the risk of exercise-related injury [20]. Total of 1538 male army recruits were randomly allocated for twelve weeks of stretching before performed active warm-up exercise and physical training. ...
Background/Purpose: Novice long distance runners may contribute to develop common lower limb injuries related to running. Strengthening hip or knee alone does not appear to prevent these injuries. Correction of running mechanics along with proper plan of regime for strengthening of lower limb is needed. The purpose of the current study was to investigate the effects of 6 weeks dynamic strength training to prevent lower limb injuries among novice long distance runners. Methods: This was an experimental study including novice runners (n=30, 18-60 years old, <2 years running experience) to evaluate the effects of dynamic strength training program specially designed under the supervision of expert physiotherapists to minimize lower limb injuries and pain. Participants were engaged in a 6-week extensive training program, three times per week using guided program comprising of various forms of exercises to strengthen their lower limb for prevention of common running injuries. Pre and Post “Knee Outcome Survey (KOS)” was measured to evaluate outcome. Results: Knee Outcome Survey Activities of Daily Living Scale (ADLS) pre training mean score was found to be 24.29 ± 5.9 whereas post training effects was 39.19 ± 2.45 with significant p-value of 0.000. In ADLS of KOS Pain variable outcome measure asked symptom that affects activity moderately the responses were 36.7% in pre whereas 0% after training. Weakness was responded mostly affecting activity moderately in 30% patients while after training it was reduced to 0%. Conclusion: A six-week dynamic strength training program may help to reduce lower limb injuries among novice long distance runners under the supervision of skilled physical therapist.
... The habit of performing stretching exercises associated with the training session or competition, regardless of the time of execution, was not effective in preventing injuries, which is consistent with other findings in the literature. 24,26,27 This was also observed, in this research project, for the group that reported the performance of specific isolated training sessions for flexibility. ...
Introduction:
Road running has been increasing dramatically in Brazil and worldwide for years. However, research into this practice has privileged high performance athletes while neglecting recreational runners, even though they constitute a significant majority of participants.
Objectives:
This study analyzed the associations between demographic and training characteristics of recreational runners in 5 km, 10 km and half marathon events, and the occurrence of musculoskeletal injuries.
Methods:
The study used data from 395 adult runners (229 men and 166 women, respectively aged 37.9 ± 9.5 and 37.1 ± 8.7 years, body weight 77 ± 10.5 and 61 ± 9 kg, and height 1.75 ± 0.07 m and 1.62 ± 0.07 m), who voluntarily and anonymously answered a questionnaire available on the Internet.
Results:
Plantar fasciitis, chondromalacia patellae (runner's knee) and tibial periostitis were the most frequently mentioned injuries in both sexes. Predisposing factors for injury (longer running time, average weekly mileage, maximum mileage and average speed in a workout) predominated in the male group, which had more types of injury and longer layoffs for this reason. Most respondents (63.3% men and 60.2% women) did not perform isolated stretching exercises; in those who did perform these exercises, and in those who stretched before and/or after training for races or competitions, there was no reduction in the incidence of injuries.
Conclusion:
Men showed a tendency towards greater intensity and volume of race training, in addition to longer running time, which are predisposing factors for injury. This may explain the greater number of different injuries reported in the male group, as well as the longer layoff periods. Level of evidence II; Prognostic studies - Investigating the effect of patient characteristics on disease outcome.
... Some studies have shown that decreased hamstring flexibility is a risk factor for the development of patellar tendinopathy and patellofemoral p a i n , hamstring s t r a i n injury a n d s y m p t o m s o f muscle damage following eccentric exercise. [6][7][8][9] Body balance consists of maintaining the centre of gravity within the base of support defined by the feet, and it may be static or dynamic. 10 In static balance, the base of support remains fixed while the centre of gravity moves. ...
Background: Prevalence of hamstring muscle tightness among undergraduate students shows 40.17%. Hamstring muscle tightness is "inability to extend the knee completely when the hip is flexed accompanied by discomfort or pain along the posterior thigh and/or knee is usually attributed to. Dynamic soft tissue mobilization developed with the aim of increase muscle length. It utilizes combine technique classic massage followed by dynamic component with the limb is moved through its range. Retro-walking is a dynamic activity which can improve be used to treat the flexibility as well as dynamic balance. Aim: To find out the effect of dynamic soft tissue mobilization with retro-walking on hamstring flexibility and dynamic balance in young collegiate students. Methodology: 25 subjects were selected Based on the selection criterion, the whole procedure of the study was explained to all the subjects. Prior and after to treatment both the outcome measures, Active Knee Extension Test and Y-Balance Test were measured. Intervention in the form of Dynamic Soft Tissue Mobilization Technique with Retro-walking were given alternate 3 sessions per week for 4 weeks. Results and Discussion: The data were analysed by Paired t test. P value for both the outcome measures were <0.05 which shows significant improvement by improving flexibility and dynamic balance. Conclusion: Intervention of the study was effective, very simple and easy to apply in Hamstring tightness subjects. So it can be implemented clinically as well.
... The findings of MSFT performance and injury risk in this study is in line with previous research in military recruits, in which Pope et al. (31) showed that those recruits who scored less than 52 shuttles (Level 7-1) were five times more likely to sustain an injury than those who scored 105 shuttles (Level 11-11) or more. Lower limb injury risk is much higher in recruits with lower fitness levels (when compared to their cohort), highlighting that fitness may be a modifiable risk factor for injury reduction (32). ...
Lower levels of fitness are associated with an increased risk of injury in police recruits. The aim of this study was to determine the relationships between initial aerobic performance assessments and injury risk during police recruit training. Retrospective data from 219 police recruits undergoing training program at a state police training academy, including 20-m Multistage Fitness Test (MSFT) and 30-15 Intermittent Fitness Test (IFT) scores and injury data, were collected. Spearman's correlation analysis revealed a significant negative correlation between levels of fitness (MSFT rs = - 0.292, p < 0.001: 30-15 IFT rs=-0.315, p < 0.001) and rates of injury. Furthermore, a Pearson's correlation showed a strong correlation between MSFT and the 30-15 IFT scores (r = 0.877, p < 0.001). Police recruits with lower fitness were at a higher risk of injury than those with higher fitness over the duration of a recruit training program. These findings indicate that aerobic performance assessments may be used by law enforcement agencies to estimate the relative risks of injury among cadets.
... 4 As with most research on different modes of stretching, there is controversy about whether a stretching program will in fact reduce the incidence of injuries. 5 There are many stretching methods used that have demonstrated increased flexibility. Among the better known methods are: static, ballistic, dynamic, and proprioceptive neuromuscular facilitation (PNF). ...
Background: There is continued controversy related to flexibility gains from different stretching protocols and within single protocols. Stretching methods include static, ballistic, dynamic, and proprioceptive neuromuscular facilitation (PNF). A combination of stretching methods may be an improved way to increase active knee range of motion (ROM). This study evaluated a single program formulated with static and ballistic components. Objective: To compare active knee ROM following stretching programs which either included combined static and ballistic stretching (CSBS) or static stretching (SS) alone. It was hypothesized that CSBS would show a greater increase in active knee ROM than SS. Setting: The pre- and post- measurements were performed in a laboratory. Subjects were randomly assigned to either treatment group or a non-stretching control group and given written instructions on how to perform their designated protocol at home. Subjects: Forty-three (33M, 10F) healthy collegiate aged participants (24.0 + 3.69 yrs, 176.21 + 10.0 cm, 78.15 + 12.93 kg) with no history of injury to the lower extremity or low back for the previous 6 months were eligible to participate in the study. Interventions: Two treatment groups either performed SS or CSBS for 30 seconds on each leg, twice a day for 2 weeks. All subjects but 3 provided both legs, and each leg was evaluated separately, providing 83 total measurements. Main Outcome Measures: A Johnson Digital Inclinometer was used to measure active knee extension. A mixed ANOVA with a Tukey post hoc test was used for statistical analysis. Results: There was no statistically significant difference in active knee ROM between groups at the pre-test, F(2,80)=1.062, p=.351, partial ƞ2=.026 (SS: 52.56 + 7.50º, CSBS: 49.84 + 8.91⁰, control: 49.39 + 10.09⁰). There was a statistically significant difference in active knee ROM between groups at the post-test, F(2,80)=29.034, p<.001, partial ƞ2=.421, with SS (67.21 + 8.23º) and CSBS (65.32 + 7.89º) greater than the control group (49.30 + 12.33º). However, the two stretching programs were not statistically significantly different from one another (p= .767, > .05). There was homogeneity of covariances, as assessed by Box's test of equality of covariance matrices (p = .076). There was homogeneity of variances, as assessed by Levene's test of homogeneity of variance (p>.05). Conclusions: SS and CSBS are equally effective for improving active knee ROM. A trend indicating CSBS showing only slightly greater differences may be due to limited time allowed to master the CSBS method, with no supervision during stretching sessions.
... Research shows that static stretching performed before exercise can temporarily compromise the muscle's ability to perform and generate maximum strength and power. 3,6,7 However, it is important to understand the mechanisms that are stimulated when we subject the human body to certain situations, such as static stretching exercises. ...
... Además, el déficit en el rendimiento del deportista después de realizar estiramientos estáticos puede llegar a durar hasta 60 min [295], aunque las causas que producen esta disminución todavía no están muy claras (ej., cambios en la actividad neuromuscular, la rigidez musculo-tendinosa…). Además, aunque a pesar de que hasta el momento la literatura científica no concluye que la realización de ejercicios de estiramientos estáticos realizados antes de la competición o entrenamiento, puedan aumentar o disminuir el riesgo de sufrir lesión [256,272,296], la idea del efecto preventivo del estiramiento, no se ha basado tanto en las evidencias científicas, sino más bien en observaciones no sistemáticas y empíricas [270,297]. Así que si la inclusión de estiramientos estáticos es percibida como necesaria en determinadas articulaciones y en deportistas concretos, su introducción debe de hacerse de forma planificada, minimizando en todo lo posible el tiempo de trabajo pasivo y combinando el mismo con ejercicios dinámicos, balísticos y/o reactivos. ...
... Flexibility is suggested to benefits in improving athletic execution, diminishing damage hazard, aversion or decrease of post-practice soreness and improving co-appointment (Pope, Herbert & Kirwan, 2000). Previous studies by Hartig and Henderson (1999) and Kujala, Orava, and Järvinen (1997) claimed that by improving hamstring flexibility, it will significantly decrease the number of overuse injuries. ...
Futsal is a high intensity team sport game that demands a high physical, technical and tactical ability. The elements of kicking and jumping demands a strong lower body, in which quadriceps act as the primary muscles, whereas the hamstring act as the balancer of the knee joint. The aim of the study was to investigate the effect of eccentric strength training and static stretch on hamstring flexibility among futsal players. 10 recreational male futsal players (n=10) recruited from Universiti Teknologi MARA (UiTM) Samarahan for the study. Subjects were randomly assigned into two groups comprised of eccentric strength training group and static stretching group. Eccentric strength training performed the Nordic hamstring exercise while, static stretch group performed static stretching exercise. All participants went through a 4 weeks program respectively to the set group, with 3 sessions each week. Sit and reach flexibility test was measured. Both groups showed a significant improvement in hamstring flexibility between pre and post-test, eccentric strength training (p=0.01) and static stretching (p=0.01). Thus, both programs are applicable in order to enhance hamstring flexibility and may improve the performance.
... Naturally, injury prevention is an issue that has drawn a considerable amount of attention in sports [21][22][23][24][25][26][27]. Generally, studies have approached the issues of prevention of lower extremity injuries from the most diverse points of view, like in foot orthoses [28][29][30][31][32], external orthoses [33][34][35], balance training [36][37][38][39][40], stretching [41][42][43][44][45], strength training [46][47][48][49][50] and multi-intervention programs, with [51][52][53] and without specific equipment [54][55][56]. To our best knowledge, none of these studies included futsal players. ...
Background: Futsal is considered to be the world’s fastest growing indoor sport. Being a multiple-sprints sport, with a high intensity level of play, the players are submitted to high risk of injury. The fast growth in the rates of futsal participation is increasing the awareness and concern regarding the public health significance of futsal injuries.
Objectives: This narrative review aims to provide an overview of the specificities of futsal, injury incidence in futsal, and current evidence regarding the effects of injury prevention programs, focusing on the FIFA 11+, in futsal and football.
Major Findings: Futsal involves a considerable number of high-intensity phases in terms of proportion of match time, which may help to justify a high rate of injuries in futsal. The most prevalent time-loss injuries in futsal are the ankle sprain, groin and thigh strains. Injury prevention programs have led to significant reduction in injuries amongst football players. The majority of studies performed so far in football players to analyze the risk of injuries with the FIFA11+ showed significant risk reductions; there is a clear need for studies in futsal players, as only one study was identified showing a reduction of overall, acute and lower limb injuries during the season. Four studies assessed the impact of the FIFA11+ on physical performance in futsal players, showing positive results in knee muscle strength.
Conclusions: Considering that the main injury in futsal is the ankle sprain, the injury risk reduction observed in football and futsal players after the FIFA 11+, and the positive effects of the program in some physical parameters (e.g. muscle strength) in futsal players, it seems reasonable to suggest the use of the FIFA 11+ to reduce injury risk in futsal players.
... Three trials investigated the effect of static stretching compared to no stretching on all types of MSIs (eg, bone, joint, muscle/tendon, spinal injuries) 44 and lower limb injuries, with moderate risk of bias. 45,46 The pooled estimate showed a small and nonsignificant effect on total injury risk (see Figure 3: I 2 = 0%, RR = 0.93, 95% CI 0.79-1.09). Although stretching protocols differed, none of the trials individually provided evidence to support static stretching prior to exercising or stretching regularly outside of exercising for preventing all types MSIs. ...
Objective:
To evaluate the effect of exercise programs on reduction of musculoskeletal injury (MSI) risk in military populations.
Design:
Systematic review and meta-analysis.
Literature survey:
A database search was conducted in PubMed/MEDLINE, EMBASE, Cochrane Library, CINAHL, SPORTdiscus, WHO International Clinical Trials Registry Platform Search Portal, Open Grey, National Technical Reports Library and reference lists of included articles up to July 2019. Randomised and cluster-randomised controlled trials evaluating exercise programs as preventive interventions for MSIs in armed forces compared to other exercise programs or to usual practice were eligible for inclusion.
Methodology:
Two authors independently assessed risk of bias and extracted data. Data were adjusted for clustering if necessary and pooled using the random-effects model when appropriate.
Synthesis:
We included 15 trials in this review, with a total number of 14 370 participants. None of the included trials appeared to be free of any risk of bias. Meta-analysis and GRADE-assessment could be performed for static stretching compared to no stretching (3532 participants), showing low quality of evidence indicating no favourable effect of stretching. Gait retraining, an anterior knee-pain targeted program and resistance exercises showed cautious favourable effects on reducing injury risk in military personnel.
Conclusion:
The current evidence base for exercise-based MSI prevention strategies in the military is of low quality. Areas worthy of further exploration include gait retraining, anterior knee-pain targeted programs, agility training, and resistance training programs, on medial tibial stress syndrome incidence, anterior knee pain incidence, attrition due to injuries and any type of MSI, respectively. This article is protected by copyright. All rights reserved.
... It has also been revealed that greater volumes of SS have a larger negative effect on subsequent anaerobic fitness test performance compared to smaller volumes of SS (32,38). Furthermore, there is little evidence to support the relation between SS and injury risk reduction despite popular belief (29,37). If SS were performed in isolation as the only component of warm-up, it is highly likely that the individual would not elicit additional physiological changes associated with DS (5-7). ...
Proper warm-up is important for facilitating peak athletic performance and reducing injury risk; yet, warm-up procedures vary considerably amongst coaches and athletes. The purpose of this study was to assess the effect of a static stretching, medicine-ball, and mini-band warm-ups relative to a light jogging warm-up only on athletic ability test performance. It was hypothesized that static stretching would negatively affect performance, while medicine-ball and mini-band warm-ups would positively affect performance relative to light jogging only. Twelve female collegiate soccer players (19.3 ± 1.2y, 65.2 ± 7.5kg, 1.67 ± 0.07m) participated in this study. Athletes completed each warm-up protocol and all of the athletic performance tests over four sessions in a semi-randomized, counterbalanced order. An omnibus MANOVA with vertical jump height, medicine ball throw distance, 10m and 20m sprint time, and T-test time as the dependent variables was not significant indicating that warm up did not have an effect on subsequent athletic ability test performance [Wilks' λ = 0.64, F(15,110) = 1.28, p = 0.23, η2 = 0.14]. Static stretching warm-up did not negatively influence athletic potential compared to mini-band and medicine ball warm-ups, though the most optimal warm-up is likely athlete specific.
... Metaanaliza ni pokazala učinkovitosti gibalno-terapevtskih intervencij pri zmanjševanju incidence za nastanek tekaških poškodb. Od sedmih intervencij sta se po le ena gibalno-terapevtska (Pope, 2000) in ena trenažna intervencija izkazali kot učinkoviti (Rudzki, 1997) izkazala za preventivno. Ugotavljamo, da je število visoko kakovostnih študij, ki bi preučevale preventivne vplive gibalno-terapevtskih intervencij, malo. ...
The monograph presents the author’s biomechanical technology of injury prevention in the climbing. The developed technology contains 3 directions: 1 — theoretical and methodical (creation of bases for understanding by students of mechanisms of formation of movements without risk of injury, formation at students of concept of biomechanically rational movements in general); 2 — analytical (providing students with knowledge about modern means of self-analysis of the level of technical skills); 3 — practical (sportsnen’ mastery of practical means of injury prevention, ie, exercises that will promote the formation of biomechanically rational movements in any sport, and thus prevent injury). The monograph contains an algorithm for identifying the main kinematic parameters of different models of equipment, typical for athletes with different levels of mastery of sports techniques. Based on biomechanical analysis, the main aspects of movement technique on the example of climbing, which affect the level of injuries of athletes. The monograph also presents the principles of application of means for injury prevention. The monograph contains developed and systematized tools to prevent injuries to athletes. The effectiveness of biomechanical technology in the use of neuromuscular training using exercises in a closed kinematic circuit, exercises in eccentric mode in combination with strength exercises for injury prevention and the formation of effective movement techniques for climbing.
The aim of the present study was to examine the time course of changes of the effects of static stretching on straddle jump, vertical jump height and flexibility after performing dynamic movements in artistic gymnasts. The study was participated by 14 female artistic gymnasts aged between 9 and 14. Vertical jump heights were measured using the New Test 2000 testing device. Flexibility measurement was performed with sit and reach flexibility test. Artistic gymnastics-specific jump movement was evaluated looking at the angle between lower extremities using the Dartfish motion analysis program. Baseline measurements taken before the standard warm-up and the measurements taken after static stretching were assessed. Four sets of gymnastics moves each lasting two minutes were performed. The tests were repeated after each set. Static stretching was found to affect vertical jump performance significantly. Significant differences were found between Jump2 and Jump1 (p=0.01), Jump2 and Jump3 (p=0.03), Jump2 and Jump4 (p=0.01), Jump2 and Jumop5 (p=0.004), and Jump2 and Jump6 (p=0.009). In flexibility-related changes, significant differences were found between Reach2 and Reach3 (p=0.03), and Reach2 and Reach6 (p=0.006). Static stretching was found to have no significant effect on the lower extremity straddle jump degree. In conclusion, although the static stretching protocol reduced vertical jump performance significantly, it did not affect the artistic gymnastics-specific jump move. The negative effects of static stretching on jump height approached the baseline value approximately 4 minutes later.
Neuromuscular warm-up exercises (NMWU) have been shown to prevent injuries. In dance, research on warming-up is scarce. We investigated warm-up habits among ballet dancers and the effects of NMWU and traditional ballet specific warm-up (TBSWU) on injuries. Using a cross-sectional survey among ballet dancers over the age of 18 years, we recorded acute and overuse injuries sustained in the previous 2 years. Warm-up behavior was assessed through 28 items. Dancers were grouped into NMWU or TBSWU: NMWU was based on neuromuscular warm-up programs in sports science and included exercises improving strength, power, proprioception, sensorimotor control, or cardiovascular stimulus; and TBSWU consisted of stretching, dance-technical exercises, marking steps and running-through-choreographies, or stretching with tools. Separate linear regression analyses adjusted for confounding factors were performed for acute and overuse injuries. A total of 192 dancers (26.7 ± 7.82 years, 159 females, 132 professionals) reported 203 acute and 469 overuse injuries. In total, 47.4% of dancers always warmed up (mean duration 20.7 ± 13.2 minutes) based on stretching (63%), technical-exercises (58.9%), strength-training (54.7%), and the barre (53.6%); and 9.4% never warmed up. A total of 31 dancers (16.15%) were classified as TBSWU, 16 dancers (8.3%) for NMWU, and 145 dancers did combined exercises. Those in the NMWU group were associated with fewer overuse injuries compared to those in the TBSWU group (β = -2.34; 95%CI -3.54 to -1.14). No association was found with acute injuries. As in other athletes, NMWU might be protective against overuse injuries in dancers. Large-scale prospective cohort studies are needed to gain more insight into NMWU as a possible component of injury prevention in ballet.
Velodrome cycling is a sport that requires cycling on an inclined surface, and this may increase chances of injury in players. The purpose of this study was to find out the injury pattern in form of injured part, injury time, severity, type and relation with gender, level of participation and training characteristics among velodrome cycling players. Injury pattern from the last 2 years was studied in 85 velodrome cycling players aging between 15-25 years from Punjab using a scheduled interview method. The study included players who were practicing cycling at least 3 times per week for more than 2 years. The mean age of the study participants was 19.39 years (range 15-25). According to the results of this study, 48 out of 85 cyclists had sustained 75 injuries in the last 2 years, in which 52% (39) injuries were due to fall, 66.67% were traumatic injuries and 84% occurred during training time. The most commonly injured parts were shoulder and knee. For the shoulder, the clavicle was the most frequently fractured bone (11 cases) among the 85 cyclists. The severity of injuries calculated according to Ekstrand’s 3-point scale based on absence from the sports activity depicted most injuries as severe (39.58%) followed by mild (33.33%) and moderate (27.08%). It can be concluded that females were injured more as compared to male velodrome cyclists. The most common injured parts were shoulder in upper limb and knee in lower limb.
Background
A large volume of systematic reviews and meta-analyses has been published on the effectiveness of sports injury prevention programs.
Purpose
To provide a qualitative summary of published systematic reviews and meta-analyses that have examined the effectiveness of sports injury prevention programs on reducing musculoskeletal injuries.
Study Design
Systematic review; Level of evidence, 4.
Methods
We searched the PubMed, CINAHL, EMBASE, and the Cochrane databases for systematic reviews and meta-analyses that evaluated the effectiveness of sports injury prevention programs. We excluded published abstracts, narrative reviews, articles not published in English, commentaries, studies that described sports injury prevention strategies but did not assess their effectiveness, studies that did not assess musculoskeletal injuries, and studies that did not assess sports-related injuries. The most relevant results were extracted and summarized. Levels of evidence were determined per the Oxford Centre for Evidence-Based Medicine, and methodological quality was assessed using the AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews, revised version).
Results
A total of 507 articles were retrieved, and 129 were included. Articles pertaining to all injuries were divided into 9 topics: sports and exercise in general (n = 20), soccer (n = 13), ice hockey (n = 1), dance (n = 1), volleyball (n = 1), basketball (n = 1), tackle collision sports (n = 1), climbing (n = 1), and youth athletes (n = 4). Articles on injuries by anatomic site were divided into 11 topics: general knee (n = 8), anterior cruciate ligament (n = 34), ankle (n = 14), hamstring (n = 11), lower extremity (n = 10), foot (n = 6), groin (n = 2), shoulder (n = 1), wrist (n = 2), and elbow (n = 1). Of the 129 studies, 45.7% were ranked as evidence level 1, and 55.0% were evidence level 2. Based on the AMSTAR-2, 58.9% of the reviews reported a priori review methods, 96.1% performed a comprehensive literature search, 47.3% thoroughly described excluded articles, 79.1% assessed risk of bias for individual studies, 48.8% reported a valid method for statistical combination of data (ie, meta-analysis), 45.0% examined the effect of risk of bias on pooled study results, and 19.4% examined the risk for publication bias.
Conclusion
This comprehensive review provides sports medicine providers with a single source of the most up-to-date publications in the literature on sports injury prevention.
Background:
Stretching is believed to decrease muscle strength. The aim of this paper was to examine the time course (immediate, and 10- and 20-minutes post-stretching) for the effects of 2, 4, and 8 minutes of static-stretching (SS) on the isometric maximum voluntary contraction force (MVCF) of hamstring muscles with a pretest-post-test experiment design.
Methods:
A total of 14 subjects with a mean age of 25 years participated in three experimental trials on three different days. Day I for static stretching for 2 minutes (SS 2 ), day II for 4 minutes (SS 4 ), and day III for 8 minutes (SS 8 ). Testing was conducted before (pre), immediately after (post), and at 10- and 20-minutes post-stretching. MVCF was measured using the strain gauze as the main outcome measure.
Results:
MVCF increased with SS 2 at 0 minutes (1.31%), 10 minutes (3.4%), and 20 minutes (4.1%) postintervention. MVCF increased with SS 4 at 0 minutes (1.13%), 10 minutes (9.6%) and 20 minutes (7.1%) postintervention. MVCF decreased with SS 8 at 0 minutes (2.9%), but increased at 10 minutes (1.86%) and 20 minutes (0.99%) postintervention. All these changes were not statistically significant (P>0.05).
Conclusions:
In hamstring stretching, 2, 4 and 8 minutes increased MVCF, but results were not statistically significant. Thus, 2 to 8 minutes long-duration stretching exercises could safely be performed before a strength-training session.
Training Science and Rehabilitation Supportive factors for the incidence and occurrence of injury for junior Athletes.
A prática de surfe tem tido um grande destaque em todo o mundo. Seus adeptos têm aumentado de forma considerável, tornando-o o esporte náutico mais praticado atualmente. Por ser um esporte que requer grande esforço físico e mudanças bruscas de postura seus atletas estão sempre em grande risco de desenvolver lesões. Assim o objetivo desse estudo foi elencar as lesões que mais acometem os praticantes do surfe, bem como a conduta dos atletas para evitarem tais lesões e ainda compreender a importância do fisioterapeuta na prevenção e tratamento de lesões esportivas. A metodologia utilizada nesta pesquisa foi uma revisão de literatura, onde foram realizadas buscas literárias sobre este assunto em bases de dados eletrônica como Google Acadêmico, Scientific Eletronic Library Online (Scielo), PubMed, com o propósito de analisar e sintetizar as informações encontradas. Através deste estudo foi possível verificar as principais características das lesões que acometem os atletas do surfe. Sendo assim, é de grande valia o entendimento do gestual esportivo dessa modalidade e as condutas a serem tomadas com o intuito de minimizar o risco de lesões e visando os benefícios que promovam analgesia, melhora da flexibilidade, da força muscular, do condicionamento físico e cardiorrespiratório, constatando então que, o planejamento de um programa de prevenção de lesões com atletas do surfe, pode ser considerado um excelente método para redução de lesões.
Of all sports-related injuries treated in the emergency room, basketball accounts for over 34%. Basketball-related injuries are the most common type of sports-related injury in patients under the age of 25 years and second in those aged 25–40 years. The ankle is by far the most common joint injured in the National Basketball Association, with ankle sprains being the most common type of injury to the ankle. Prevention strategies, functional rehabilitation, and judicious use of operative intervention are all important in the management of the injured basketball player for safe and timely return to play.
En las últimas décadas ha aumentado el número de participantes en carreras populares de resistencia, sobre todo, de atletas veteranos. El objetivo de este estudio es determinar las características sociodemográficas del atleta veterano en relación a variables personales, de entrenamiento y lesión. Se elaboró un cuestionario ad hoc con estas variables. El perfil del corredor veterano es un varón en torno a los 40 años, con estudios universitarios, que trabaja y vive en pareja, que entrena 4 días a la semana y recorre sobre 50 kilómetros semanales. Se destaca la alta prevalencia de lesiones en esta población y el único factor que predispone a la lesión es el número de sesiones semanales de entrenamiento.
Rev Bras Cineantropom Desempenho Hum 2010, 12(3):195-201 Resumo-O objetivo deste estudo foi investigar, em mulheres idosas, o efeito agudo do alongamento estático sobre a taxa de desenvolvimento de força pico (TDFP) e contração voluntária máxima (CVM). A amostra foi composta por 10 mulheres idosas (idade 68,5 ± 7,0 anos; peso 70,9 ± 8,1 kg; estatura 159,4 ± 6,0 cm; índice de massa corporal 28,0 ± 3,8 kg/m 2). A TDFP e a CVM foram testadas no exercício Leg Press, antes e após as condições controle ou alongamento (três séries de 30 segundos de alongamento estático do quadríceps femoral), em dois dias diferentes (24 horas de intervalo). A TDFP foi determinada como a inclinação mais íngreme da curva, calculada dentro da janela regular de 20 ms (∆Força/∆Tempo), para os primeiros 200 ms após o início da força muscular. A CVM foi determinada como o maior ponto registrado na tentativa. Em cada dia, apenas uma condição foi testada e a ordem de emprego para cada condição foi determinada aleatoriamente. A intensidade do alongamento foi determinada pelo limiar de dor muscular. Quatro avaliações pós-condições (pós-tratamento; 10; 20 e 30 minutos) foram realizadas para acompanhar o comportamento da força muscular. A ANCOVA 2x5, seguida do teste post-hoc de Scheffé, não mostrou interações, condição vs. momento, significativas (P > 0,05) para a TDFP e CVM. Em conclusão, séries agudas de alongamento estático para o quadríceps femoral não afetam a capacidade de produzir força muscular rapidamente e máxima de mulheres idosas. Palavras-chave: Envelhecimento; Aquecimento; Curva força-tempo Isométrica. Abstract-The objective of this study was to investigate the acute effect of static stretching on the peak rate of force development (PRFD) and maximum voluntary contraction (MVC) in older women. Ten women (68.5 ± 7.0 years; 70.9 ± 8.1 kg; 159.4 ± 6.0 cm; body mass index: 28.0 ± 3.8 kg/m 2) were studied. MVC and PRFD were determined by leg press exercise before and after the control or stretching condition (three sets of 30 seconds of static stretching of the quadriceps) on two different days (interval of 24 hours). PRFD was determined as the steepest slope of the curve, calculated within regular windows of 20 milliseconds (∆force/∆time) for the first 200 milliseconds after the onset of contraction. MVC was determined as the highest value recorded in each set. Only one condition was tested on each day and the order of application of each condition was determined randomly. The stretching intensity was evaluated by the muscle pain threshold. Four post-condition assessments (post-treatment, 10, 20, and 30 minutes) were performed to monitor muscle strength. ANCOVA 2x5, followed by the Scheffé post-hoc test, showed no significant interactions between conditions vs. times (P > 0.05) for PRFD or MVC. In conclusion, acute bouts of static stretching of the quadriceps femoris do not affect the ability of rapid and maximum muscle force production in older women.
Aim
Functional movement screen (FMS) is a system based on scoring seven movement patterns that
form the basis of human movement according to certain criteria. The purpose of this study is to
compare the FMS scores of male soccer players who aged 13 years with the FMS scores of male
soccer players who aged 17 years.
Method
29 boys who playing football in a football academy were taken to study. Players with any
musculoskeletal injuries were not included in the study. FMS evaluation was done by the same tester.
Results
The mean of the FMS scores of the 13-year-old participants was 14.07 ± 1.63, and the FMS
scores of the 17-year-old participants was 16.60 ± 1.50. The difference between the FMS scores of
the two age groups was statistically significant (p <0.05). In addition, the scores of the 13-year-old
group were at the limit for risk for musculoskeletal injury according to this scoring system.
Conclusion
Considering the findings, it can be concluded that male children playing football at the
age of 13 are more vulnerable to musculoskeletal injuries than those of 17 years old.
Background:
Achilles injuries are devastating injuries, especially for competitive athletes. No studies have examined the outcomes of Achilles injuries in NCAA athletes. Therefore, a better characterization and understanding of the epidemiology is crucial.
Methods:
Achilles injuries across 16 sports among NCAA men and women during the 2004-2005 to 2013-2014 academic years were analyzed using the NCAA Injury Surveillance Program (NCAA-ISP). Achilles tendon injury rate (IR) per 100,000 athlete-exposures (AEs), operative rate, annual injury rate trends, reinjury rates, mechanism of injury, in-season status (pre/regular/post season), and time loss distributions were compiled and calculated. A sub-analysis of comparing gender and injury mechanism was also performed for both all injuries and severe injuries.
Results:
Overall, N = 255 Achilles injuries were identified with an injury rate (IR) of 2.17 (per 100,000 AEs). These injuries occurred most often in women's gymnastics (IR = 16.73), men's basketball (IR = 4.26), and women's basketball (IR = 3.32), respectively. N = 52 injuries were classified as severe injuries which have higher median time loss (48 days) and higher operative rate (65.4%). For severe Achilles injuries, female athletes had higher operative (77.8% vs. 58.8%) and higher time loss compared to male athletes (96 days vs. 48 days). Contact mechanisms were associated with a higher season-ending injury rate.
Conclusion:
Overall, 20.4% of Achilles injuries were considered severe with 65.6% operative rate. About 73.1% were season-ending injuries, and the remaining athletes have a median time loss of 48 days. Severe Achilles injuries create significant impact on playing time and career for NCAA athletes.
Exercise related leg pain in the military. Treatment of MTSS and CECS, with an emphasis on gait retraining.
To date, limited information exists describing a relatively new stretching technique, dynamic range of motion (DROM). The purpose of this study was to compare the effects of DROM with static stretch on hamstring flexibility. Fifty-eight subjects, ranging in age from 21 to 41 years and with limited hamstring flexibility (defined as 30 degrees loss of knee extension measured with the femur held at 90 degrees of hip flexion), were randomly assigned to one of three groups. One group performed DROM 5 days a week by lying supine with the hip held in 90 degrees of flexion. The subject then actively moved the leg into knee extension (5 seconds), held the leg in end range knee extension for 5 seconds, and then slowly lowered the leg to the initial position (5 seconds). These movements were performed six times per session (30 seconds of total actual stretching time). The second group performed one 30-second static stretch, 5 days per week. The third group served as a control group and did not stretch. Before and after 6 weeks of training, flexibility of the hamstring muscles was determined in all three groups by measuring knee extension range of motion (ROM) with the femur maintained in 90 degrees of hip flexion. Data were analyzed with a 2 x 3 (test x group) two-way analysis of variance (ANOVA) with repeated measures on one variable (test) and appropriate post hoc analyses. The results of the two-way ANOVA revealed a significant interaction. Further statistical post hoc analysis of data to interpret the interaction revealed significant differences between the control group (gain = 0.70 degree) and both stretching groups, as well as a significant difference between the static stretch group (gain = 11.42 degrees) and the DROM group (gain = 4.26 degrees). The results of this study suggest that, although both static stretch and DROM will increase hamstring flexibility, a 30-second static stretch was more effective than the newer technique, DROM, for enhancing flexibility. Given the fact that a 30-second static stretch increased ROM more than two times that of DROM, the use of DROM to increase flexibility of muscle must be questioned.
The benefits of physical activity are widely known. However, the risk of a musculoskeletal injury is an unfavourable consequence in physical training. Age, gender, injury history, body size, local anatomy and biomechanics, aerobic fitness, muscle strength, imbalance and tightness, ligamentous laxity, central motor control, psychological and psychosocial factors as well as general mental ability are factors in the predisposition to injury.
Junior (15 to 16 years) and senior athletes seem to be at a higher risk of injury in many types of sport. However, the relationship between age and injuries apparently depends on both the type and intensity of activity practiced. The majority of injured athletes in many studies have been males. Men are, however, more likely to participate in vigorousexercise and sport and it is not known if men are at a generally higher risk of injury when the exposure is taken into account. Certain lesions, such as sprains, strains and dislocations, tend to recur. Previous injuries may necessarily not cause a repetition of injury if treated adequately, but certain individuals may be at a higher risk of injury due to injury-prone biological characteristics. Excessive height and weight have been shown to predispose to stress injuries in physical training. Idiopathic or acquired abnormalities in the anatomy or biomechanics in any joint may lead to a local injury. However, physical requirements vary widely between different types of activity and predisposition to injury due to anatomical or biomechanical factors seems to be characteristic for each type of exercise. Lack of fitness, muscle weakness, joint looseness and poor general flexibility have been suggested as factors in the outcome of athletic injuries but no definite conclusions can be made on the basis of the existing literature. Long simple reaction times to visual stimuli and long choice reaction times to visual stimuli have recently been related to musculoskeletal injuries. No exceptional personality dimension in injury proneness as a whole has been found and the results from specific groups cannot be extrapolated generally. Accumulation of life stress apparently predisposes to an athletic injury. Musculoskeletal injuries seem to be more common in subjects with lower scores in intelligence tests but no causation has been shown yet. Altogether, a complex network of risk factors for athletic injuries has been found. However, no prospective study including all the recognised injury risk factors has been presented in the literature. Further research is needed in the subject.
It has been shown that injury rates in athletes can be decreased by modifying coaching and efforts to prevent injuries can therefore be recommended. Each type of activity has its characteristic injury profile and degree of risk and the type of injuries vary widely. Athletes, coaches and supervisors should be aware of the risk factors concerning the specific type of activity they are involved in. Anatomical considerations, motor performance requirements and psychological factors are particularly important. In addition major exposure to injury in a state of high life stress should be avoided in any type of physical activity. Athletes, coaches and supervisors should also be aware of the relevance of adequate treatment and rehabilitation after an injury to avoid recurrence of injuries.
The purpose of this study was to assess the validity of the 1 min stage version of the 20 m shuttle run multistage test to predict VO2max in adults (53 males and 24 females, 19 to 47 years old). The maximal shuttle run speed (S-MAS) was thus compared to the VO2max attained during a multistage treadmill test (TE-VO2max), the retroextrapolated VO2max at time zero of the O2 recovery curve of the shuttle run (SR-VO2max) and the VO2max predicted from a previously developed regression equation with children (Mercier et al., 1983) and putting 18 year olds in the regression equation for all adults which yielded (SP-VO2max = -27.4 + 6.0 S-MAS). The latter regression equation was very similar to the ones obtained with the two other criteria and was thus retained to ensure a smooth transition between children and adults in predicting VO2max. Correlations and standard errors of the estimate between S-MAS and TE-VO2max (r = 0.90 and Syx = 4.4) or SR-VO2max (r = 0.87 and Syx = 4.7) were quite good. TE-, SR- and SP-VO2max were also similar (mean +/- SD = 49.4 +/- 10.1, 48.8 +/- 9.3 and 47.1 +/- 8.3 mL.kg-1.min-1, respectively, p greater than 0.05). It was concluded that the 20 m shuttle run is a valid test to predict VO2max in adults.
A maximal multistage 20 m shuttle run test was designed to determine the maximal aerobic power of schoolchildren, healthy adults attending fitness class and athletes performing in sports with frequent stops and starts (e.g. basketball, fencing and so on). Subjects run back and forth on a 20 m course and must touch the 20 m line; at the same time a sound signal is emitted from a prerecorded tape. Frequency of the sound signals is increased 0.5 km h-1 each minute from a starting speed of 8.5 km h-1. When the subject can no longer follow the pace, the last stage number announced is used to predict maximal oxygen uptake (VO2max) (Y, ml kg-1 min-1) from the speed (X, km h-1) corresponding to that stage (speed = 8 + 0.5 stage no.) and age (A, year): Y = 31.025 + 3.238 X - 3.248A + 0.1536AX, r = 0.71 with 188 boys and girls aged 8-19 years. To obtain this regression, the test was performed individually. Right upon termination VO2 was measured with four 20 s samples and VO2max was estimated by retroextrapolating the O2 recovery curve at time zero of recovery. For adults, similar measurements indicated that the same equation could be used keeping age constant at 18 (r = 0.90, n = 77 men and women 18-50 years old). Test-retest reliability coefficients were 0.89 for children (139 boys and girls 6-16 years old) and 0.95 for adults (81 men and women, 20-45 years old).(ABSTRACT TRUNCATED AT 250 WORDS)
The aim of this study was to assess the validity of a 20 metre multi-stage shuttle run (20-MST) as both a field test of cardiorespiratory endurance and as a predictor of competitive performance in a 10 kilometre (10 km) race. Nine male subjects (age 35.4 +/- 5.8 years) (mean +/- SD) underwent a laboratory test of maximum oxygen uptake on a treadmill (VO2 max 59.0 +/- 9.9 ml.kg.-1min-1), completed the 20-MST (score 105 +/- 23.7 laps/11.4 +/- 2.7 paliers) and competed in a 10 km race (finishing time 41.8 +/- 7.3 minutes). Analysis using Pearson's Product Moment Coefficient revealed high correlations between these variables (20-MST vs. VO2 max, r = 0.93; 20-MST vs. 10 km, r = -0.93; VO2 max vs. 10 km, r = -0.95). These results confirm that the 20-MST is a valid field test of cardio-respiratory endurance and suggest that it can additionally be used to predict relative running performance over 10 km.
To which groups of patients can the results of clinical trials be applied? This question is often inappropriately answered by reference to the trial entry criteria. Instead, the benefit and harm (adverse events, discomfort of treatment, etc) of treatment could be assessed separately for individual patients. Patients at greatest risk of a disease will have the greatest net benefit as benefit to patients usually increases with risk while harm remains comparatively fixed. To assess net benefit, the relative risks should come from (a meta-analysis of) randomised trials; the risk in individual patients should come from multivariate risk equations derived from cohort studies. However, before making firm conclusions, the assumptions of fixed adverse effects and constant reduction in relative risk need to be checked.
To date, there are no reports comparing duration of static stretch in humans on joint range of motion (ROM) and hamstring muscle flexibility. The purpose of this study was to examine the length of time the hamstring muscles should be placed in a sustained stretched position to maximally increase ROM.
Fifty-seven subjects (40 men, 17 women), ranging in age from 21 to 37 years and with limited hamstring muscle flexibility (ie, 30 degrees loss of knee extension measured with femur held at 90 degrees of hip flexion), were randomly assigned to one of four groups. Three groups stretched 5 days per week for 15, 30, and 60 seconds, respectively. The fourth group, which served as a control group, did not stretch.
Before and after 6 weeks of stretching, flexibility of the hamstring muscles was determined by measuring knee extension ROM with the femur maintained in 90 degrees of hip flexion. Data were analyzed with a 4 x 2 analysis of variance (group x test) for repeated measures on one variable.
The data analysis revealed a significant group x test interaction, indicating that the change in flexibility was dependent on the duration of stretching. Further post hoc analysis revealed that 30 and 60 seconds of stretching were more effective at increasing flexibility of the hamstring muscles (as determined by increased ROM of knee extension) than stretching for 15 seconds or no stretching. In addition, no significant difference existed between stretching for 30 seconds and for 1 minute, indicating that 30 seconds of stretching the hamstring muscles was as effective as the longer duration of 1 minute.
The results of this study suggest that a duration of 30 seconds is an effective time of stretching for enhancing the flexibility of the hamstring muscles. Given the information that no increase in flexibility of the hamstring muscles occurred by increasing the duration of stretching from 30 to 60 seconds, the use of the longer duration of stretching for an acute effect must be questioned.
Physical training-related injuries are common among army recruits and other vigorously active populations, but little is known about their causation. To identify intrinsic risk factors, we prospectively measured 391 army trainees. For 8 weeks of basic training, 124 men and 186 women (79.3%) were studied. They answered questionnaires on past activities and sports participation, and were measured for height, weight, and body fat percentage; 71% of the subjects took an initial army physical training test. Women had a significantly higher incidence of time-loss injuries than men, 44.6% compared with 29.0%. During training, more time-loss injuries occurred among the 50% of the men who were slower on the mile run, 29.0% versus 0.0%. Slower women were likewise at greater risk than faster ones, 38.2% versus 18.5%. Men with histories of inactivity and with higher body mass index were at greater injury risk than other men, as were the shortest women. We conclude that female gender and low aerobic fitness measured by run times are risk factors for training injuries in army trainees, and that other factors such as prior activity levels and stature may affect men and women differently.
To examine electromyography (EMG) activity, passive torque, and stretch perception during static stretch and contract-relax stretch.
Two separate randomized crossover protocols: (1) a constant angle protocol on the right side, and (2) a variable angle protocol on the left side.
10 male volunteers.
Stretch-induced mechanical response in the hamstring muscles during passive knee extension was measured as knee flexion torque (Nm) while hamstring surface EMG was measured. Final position was determined by extending the knee to an angle that provoked a sensation similar to a stretch maneuver. Constant angle stretch: The knee was extended to 10 degree below final position, held 10sec, then extended to the final position and held for 80 sec. Variable angle stretch: The knee was extended from the starting position to 10 degrees below the final position, held 10sec, then extended to the onset of pain. Subjects produced a 6-sec isometric contraction with the hamstring muscles 10 degrees below the final position in the contract-relax stretch, but not in the static stretch.
Passive torque, joint range of motion, velocity, and hamstring EMG were continuously recorded.
Constant angle contract-relax and static stretch did not differ in passive torque or EMG response. In the final position, passive torque declined 18% to 21% in both contract-relax and static stretch (p<.001), while EMG activity was unchanged. In the variable angle protocol, maximal joint angle and corresponding passive torque were significantly greater in contract-relax compared with static stretch(p<.01), while EMG did not differ.
At a constant angle the viscoelastic and EMG response was unaffected by the isometric contraction. The variable angle protocol demonstrated that PNF stretching altered stretch perception.
The purpose of this study was (1) to evaluate the reproducibility of a new method of measuring passive resistance to stretch in the human hamstring muscle group, in vivo, using a test re-test protocol and 2) to examine the effect of repeated stretches. Passive resistance offered by the hamstring muscle group during knee extension was measured in 10 subjects as knee flexion moment (Nm) using a KinCom dynamometer. The knee was passively extended at 5 deg/s to the final position where it remained stationary for 90 s (static phase). EMG of the hamstring muscle was also measured. The test re-test protocol included 2 tests (tests 1 and 2) administered 1 h apart. On a separate occasion 5 consecutive static stretches were administered (stretches 1-5) separted by 30 s. Stretch 6 was administered one hour after stretch 5. In the static phase passive resistance did not differ between test 1 and test 2. Resistance declined in both tests 1 and 2, whereas EMG activity remained unchanged. The decline in resistance was significant up to 45 s. For the repeated stretches there was an effect of time (90 s) and stretch (1-5) with a significant interaction i.e., resistance diminished with stretches, and the 90-s decline was less as more stretches were performed. Passive resistance in stretch 6 was lower than in stretch 1. The present study has demonstrated a reliable method for studying resistance to stretch of the human hamstring muscle group. A viscoelastic response of the human hamstring muscle was shown. With 5 repeated stretches, resistance to stretch diminished and each stretch exibited a viscoelastic response, albeit less with each subsequent stretch. The effect of 5 repeated stretches was significant 1 h later.
A total of 626 U.S. male Marine Corps recruits underwent anthropometric measurements and dual-energy X-ray absorptiometry (DXA) scans of the femoral midshaft and the distal third of the tibia prior to a 12 week physical training program. Conventionally obtained frontal plane DXA scan data were used to measure the bone mineral density (BMD) as well as to derive the cross-sectional area, moment of inertia, section modulus, and bone width in the femur, tibia, and fibula. During training, 23 recruits (3.7%) presented with a total of 27 radiologically confirmed stress fractures in various locations in the lower extremity. After excluding 16 cases of shin splints, periostitis, and other stress reactions that did not meet fracture definition criteria, we compared anthropometric and bone structural geometry measurements between fracture cases and the remaining 587 normals. There was no significant difference in age (p = 0.8), femur length (p = 0.2), pelvic width (p = 0.08), and knee width at the femoral condyles (p = 0.06), but fracture cases were shorter (p = 0.01), lighter (p = 0.0006), and smaller in most anthropometric girth dimensions (p < 0.04). Fracture case bone cross-sectional areas (p < 0.001), moments of inertia (p < 0.001), section moduli (p < 0.001), and widths (p < 0.001) as well as BMD (p < 0.03) were significantly smaller in the tibia and femur. After correcting for body weight differences, the tibia cross-sectional area (p = 0.03), section modulus (p = 0.05), and width (p = 0.03) remained significantly smaller in fracture subjects. We conclude that both small body weight and small diaphyseal dimensions relative to body weight are factors predisposing to the development of stress fractures in this population. These results suggest that bone structural geometry measurements derived from DXA data may provide a simple noninvasive methodology for assessing the risk of stress fracture.
• This prospective study of 583 habitual runners used baseline information to examine the relationship of several suspected risk factors to the occurrence of running-related injuries of the lower extremities that were severe enough to affect running habits, cause a visit to a health professional, or require use of medication. During the 12-month follow-up period, 252 men (52%) and 48 women (49%) reported at least one such injury. The multiple logistic regression results identified that running 64.0 km (40 miles) or more per week was the most important predictor of injury for men during the follow-up period (odds ratio=2.9). Risk also was associated with having had a previous injury in the past year (odds ratio = 2.7) and with having been a runner for less than 3 years (odds ratio=2.2). These results suggest that the incidence of lower-extremity injuries is high for habitual runners, and that for those new to running or those who have been previously injured, reducing weekly distance is a reasonable preventive behavior.(Arch Intern Med. 1989;149:2565-2568)
• A cohort of 1680 runners was enrolled through two community road race events and monitored during a 12-month follow-up period for the occurrence of musculoskeletal injuries. Fortyeight percent of the runners experienced at least one injury, and 54% of these injuries were new; the remainder were recurrences of previous injuries. The risk of injury was associated with increased running mileage but was relatively unassociated with other aspects of training, such as usual pace, usual running surface, hill running, or intense training. Injury rates were equal for all age-sex groups and were independent of years of running experience. Runners injured in the previous year had approximately a 50% higher risk for a new injury during follow-up.(Arch Intern Med. 1989;149:2561-2564)
We report on three epidemiologic studies of orthopedic injuries in exercisers. One group of 438 men and women ran approximately 25 mi per week; 24% reported an injury during the previous year. Higher weekly running mileage and heavier individuals were more likely to report an injury. Injuries were not associated with speed of running, age, gender, type of surface, time of day, or stretching habit. In a second study, rates of injury for the foot, knee, hip, back, shoulder, and elbow were examined in runner (n =2,102) and nonrunner (n =724) patients at a preventive medicine clinic. Only knee injury rates were significantly higher in runners. Third, participants (n=968) in worksite-sponsored exercise programs were evaluated for orthopedic injuries. Rates of exercise injuries were relatively low (net rate = 12%/year in exercisers). Risk of injury in participants starting a walking, running, or jogging program was associated (p <.05) with age, sex, body mass index, flexibility, cardiorespiratory endurance, and number of sit-ups in 1-min.
Randomized clinical trials analyzed by the intent-to-treat approach provide unbiased comparisons among treatment groups. To avoid dilution of treatment effect, many people also perform an analysis by treatment actually received, although this method may introduce bias into the results. This paper presents several approaches used for analyzing data of a recent trial and the difficulties encountered in interpreting the results of each approach.The ANRS 005/ACTG 154 Study was a double-blind, placebo-controlled, randomized, international (French, U.S., and Spanish) multicenter trial designed to assess the effectiveness of pyrimethamine for the primary prophylaxis of cerebral toxoplasmosis (CT) in HIV-infected patients with advanced immunodeficiency. In the intention-to-treat analysis, the cumulative probability of CT at 1 year did not differ significantly between the pyrimethamine arm (11.9%) and the placebo arm (13.1%), Hazard RatioHR = 0.94 95% Confidence IntervalCI = 0.62–1.42, whereas an on-treatment analysis resulted in a significant difference: 4.2% in the pyrimethamine arm and 12.4% in the placebo arm, HR = 0.44 95% CI = 0.24–0.80.The data showed a significant interaction between compliance and treatment outcome; and side effects were more frequently cited as reasons for compliance violations in the pyrimethamine group. Several different analytic approaches (censoring data at the time patients discontinued the study medication only for selected reasons) failed to explain the disparity between the estimation of effect of pyrimethamine by the intention-to-treat and on-treatment analyses.This experience led us to believe that comparing the results of both analyses was the best method to convince clinicians that intention-to-treat was the only interpretable analysis. We were concerned that even if pyrimethamine had a beneficial effect, it was very difficult (1) to quantify and (2) to apply to clinical practice unless one could predict the occurrence of study drug discontinuation for each patient at the time of treatment assignment.Although exploratory analyses may yield clinically relevant information and useful clarifications in the evaluation of treatments, intention-to-treat remains the only interpretable analysis of clinical trials.
A RANDOMIZED controlled trial (RCT) is the most reliable method of assessing the efficacy of health care interventions.1,2 Reports of RCTs should provide readers with adequate information about what went on in the design, execution, analysis, and interpretation of the trial. Such reports will help readers judge the validity of the trial.
There have been several investigations evaluating how RCTs are reported. In an early study, Mahon and Daniel3 reviewed 203 reports of drug trials published between 1956 and 1960 in the Canadian Medical Association Journal. Only 11 reports (5.4%) fulfilled their criteria of a valid report. In a review of 45 trials published during 1985 in three leading general medical journals, Pocock and colleagues4 reported that a statement about sample size was only mentioned in five (11.1%) of the reports, that only six (13.3%) made use of confidence intervals, and that the statistical analyses tended to
The purpose of this study was to determine which of three durations of a passive stretch was most effective in increasing hip abduction range of motion (ROM) in human subjects. Seventy-two men were randomly assigned into a control group and three passive stretch groups (15 seconds, 45 seconds, and 2 minutes). The two measurements used to determine hip abduction flexibility were abduction ROM and resistance to abduction force. Each subject was measured before and immediately following the passive stretch to determine changes in abduction ROM and resistance to abduction force due to a passive stretch. The results of this study indicated that hip abduction ROM was significantly increased and resistance to hip abduction force was significantly decreased after a passive stretch for all three stretch groups. There was no significant difference between mean differences of abduction ROM of the three stretch groups, except for the comparison of the 15 second and the 45 second stretch groups. The results of the force data demonstrated no significant difference between the mean differences of the three stretch groups. The fact that our data shows 15 seconds is just as effective as stretching for 2 minutes makes it reasonable to stretch for 15 seconds in athletic settings where immediate increases in abduction ROM are desired. J Orthop Sports Phys Ther 1987;8(8):409-416.
This project was supported in part by a grant from The Foundation for Physical Therapy, 1111 North Fairfax Street, Alexandria, VA 22314 Foreshortened hamstring muscles have been associated with various clinical disorders. This study examined the effects of three weeks of daily static stretching of short hamstrings on passive straight leg raising (SLR), maximal hamstring length (MHL), and their maximal resistance to passive stretch (MRPS). Twenty-four healthy men (18-37 yrs) with SLR </= 70 degrees were assigned randomly to a stretching group (N = 12) or a control group (N = 12). All subjects were positioned on their left sides with the pelvis stabilized and the right thigh fixed at 90 degrees on a horizontal platform. The right knee was then passively extended until amplified EMG activity (>50 muV) from the hamstrings was observed. The knee angle represented MHL, and MRPS (torque in nm) was calculated. Subjects in the stretching group completed daily static stretching of the hamstrings for three weeks. After three weeks, SIR increased for the stretching group, but not for the control group (< 0.001). The knee angle for the stretching group was less than the control group (p < 0.001), and the MRPS for the stretching group exceeded the control group (p < 0.05). The results indicated that static stretching increased SLR with concomitant increases in the MHL and the MRPS. The results also support using SLR as a valid clinical test for measuring hamstring length changes resulting from therapeutic interventions. J Orthop Sports Phys Ther 1991;14(6):250-255.
In order to answer the question of why the stress fracture morbidity rates among Israeli infantry recruits are so high, we prospectively evaluated 392 infantry recruits for risk factors for stress fractures. Prior to training, each recruit underwent a detailed evaluation. Using multivariate analysis, five risk factors for tibial fractures were identified: shorter tibial length (p less than 0.0001); relatively greater valgus knee alignment (p less than 0.002); right leg dominance (p less than 0.02); external rotation of the hip greater than 65 degrees (p less than 0.02); and training in specific subunits (p less than 0.0002., 0.03). No risk factors for femoral stress fracture were found by multivariate analysis.
This article addresses the medical, scientific, and practical aspects of stretching. Sections include information on the physiology of flexibility and stretching, stretching versus warm-up, and the clinical evaluation of flexibility. Detailed instructions for numerous stretching exercises for the major muscle groups are provided. Techniques for proper stretching are included.
Most muscle stretching studies have focused on defin ing the biomechanical properties of isolated elements of the muscle-tendon unit or on comparing different stretching techniques. We developed an experimental model that was designed to evaluate clinically relevant biomechanical stretching properties in an entire muscle- tendon unit. Our objectives were to characterize the viscoelastic behavior of the muscle-tendon unit and to consider the clinical applications of these viscoelastic properties.
Rabbit extensor digitorum longus and tibialis anterior muscle-tendon units were evaluated using methods designed to simulate widely used stretching tech niques. Additionally, the effects of varying stretch rates and of reflex influences were evaluated. We found that muscle-tendon units respond viscoelastically to tensile loads. Reflex activity did not influence the biomechani cal characteristics of the muscle-tendon unit in this model.
Experimental techniques simulating cyclic stretching and static stretching resulted in sustained muscle-ten don unit elongations, suggesting that greater flexibility can result if these techniques are used in the clinical setting. With repetitive stretching, we found that after four stretches there was little alteration of the muscle- tendon unit, implying that a minimum number of stretches will lead to most of the elongation in repetitive stretching. Also, greater peak tensions and greater energy absorptions occurred at faster stretch rates, suggesting that the risk of injury in a stretching regimen may be related to the stretch rate, and not to the actual technique. All of these clinically important considera tions can be related to the viscoelastic characteristics of the muscle-tendon unit.
Survival analysis is a statistical method used to calculate the probability of an event such as death or relapse of disease occurring in a patient over time. Survival analysis is important in the interpretation of clinical research, and is frequently encountered in the colorectal literature. In this article, the terminology used in survival analysis is explained, specific examples are presented, and common methods of calculation demonstrated.
This prospective study of 583 habitual runners used baseline information to examine the relationship of several suspected risk factors to the occurrence of running-related injuries of the lower extremities that were severe enough to affect running habits, cause a visit to a health professional, or require use of medication. During the 12-month follow-up period, 252 men (52%) and 48 women (49%) reported at least one such injury. The multiple logistic regression results identified that running 64.0 km (40 miles) or more per week was the most important predictor of injury for men during the follow-up period (odds ratio = 2.9). Risk also was associated with having had a previous injury in the past year (odds ratio = 2.7) and with having been a runner for less than 3 years (odds ratio = 2.2). These results suggest that the incidence of lower-extremity injuries is high for habitual runners, and that for those new to running or those who have been previously injured, reducing weekly distance is a reasonable preventive behavior.
A cohort of 1680 runners was enrolled through two community road race events and monitored during a 12-month follow-up period for the occurrence of musculoskeletal injuries. Forty-eight percent of the runners experienced at least one injury, and 54% of these injuries were new; the remainder were recurrences of previous injuries. The risk of injury was associated with increased running mileage but was relatively unassociated with other aspects of training, such as usual pace, usual running surface, hill running, or intense training. Injury rates were equal for all age-sex groups and were independent of years of running experience. Runners injured in the previous year had approximately a 50% higher risk for a new injury during follow-up.
As the number of runners has increased dramatically, so has the incidence of running-related injuries. In order to determine what training factors are associated with running-related injuries, as well as what percentage of injured runners seeks professional medical attention, a random sample of entrants to a 10 kilometer race was asked to complete a questionnaire. There were 451 respondents, 355 men and 96 women, with a nonresponse rate of 12.7%. Nonrespondents did not differ from respondents with regard to age or sex. Forty-seven percent of respondents indicated that they had sustained a running-related injury in the last 2 years. Injured runners differed significantly from noninjured runners in that they were more likely to have run more miles per week, run more days per week, run a faster pace, run more races in the last year, stretched before running, and not participated regularly in other sports. Associated with injury, but not statistically significant, were those who had run marathons and had done muscle-strengthening exercises. No association was found with regard to the length of time running, running surfaces, part of the foot first contacting the ground, or running intervals, sprints, or hills. Seventy percent of those injured sought professional medical care, with 76% of these having a good or excellent recovery from their injuries. Compliance with medical advice correlated well with treatment success.
Among modern stretching techniques none has clearly been shown to be the most effective for increasing range of motion. The most common stretching method comparisons are between static stretching (SS) and one or more Proprioceptive Neuromuscular Facilitation (PNF) technique(s). The two most frequently implemented PNF techniques are: contract-relax (CR); and contract-relax-antagonist-contract (CRAC). Previous comparative investigations among stretching methods have primarily observed changes in straight-leg hip flexion as a result of lengthening the hamstrings, a two-joint muscle. The present study observed gains in range of motion among three stretching methods (SS, CR, CRAC) of a joint limited by a single joint muscle, the soleus. Twelve subjects performed each of the three methods on separate days. Significant differences were observed among all methods (p = .001). Further analysis revealed the CRAC method was superior to the CR method (p less than .01), and the CR method was superior to the SS method (p less than .01). Significant pre-post-treatment gains in range of motion were observed as a result of the CR and CRAC methods, but not the SS method. The results of this study support the findings of those previous investigations for two-joint muscles in which PNF techniques were more effective than static stretching for increasing range of motion. Also, a reciprocal activation (CRAC in the present study) was the most effective for increasing range of motion.
Competitive and recreational athletes typically perform warm-up and stretching activities to prepare for more strenuous exercise. These preliminary activities are used to enhance physical performance and to prevent sports-related injuries. Warm-up techniques are primarily used to increase body temperature and are classified in 3 major categories: (a) passive warm-up - increases temperature by some external means; (b) general warm-up - increases temperature by nonspecific body movements; and (c) specific warm-up - increases temperature using similar body parts that will be used in the subsequent, more strenuous activity. The best of these appears to be specific warm-up because this method provides a rehearsal of the activity or event. The intensity and duration of warm-up must be individualised according to the athlete's physical capabilities and in consideration of environmental factors which may alter the temperature response. The majority of the benefits of warm-up are related to temperature-dependent physiological processes. An elevation in body temperature produces an increase in the dissociation of oxygen from haemoglobin and myoglobin, a lowering of the activation energy rates of metabolic chemical reactions, an increase in muscle blood flow, a reduction in muscle viscosity, an increase in the sensitivity of nerve receptors, and an increase in the speed of nervous impulses. Warm-up also appears to reduce the incidence and likelihood of sports-related musculoskeletal injuries. Improving flexibility through stretching is another important preparatory activity that has been advocated to improve physical performance. Maintaining good flexibility also aids in the prevention of injuries to the musculoskeletal system. Flexibility is defined as the range of motion possible around a specific joint or a series of articulations and is usually classified as either static or dynamic. Static flexibility refers to the degree to which a joint can be passively moved to the end-points in the range of motion. Dynamic flexibility refers to the degree which a joint can be moved as a result of a muscle contraction and may therefore not be a good indicator of stiffness or looseness of a joint. There are 3 basic categories of stretching techniques: (a) ballistic--which makes use of repetitive bouncing movements; (b) static--which stretches the muscle to the point of slight muscle discomfort and is held for an extended period; and (c) proprioceptive neuromuscular facilitation - which uses alternating contractions and stretching of the muscles. Each of these stretching methods is based on the neurophysiological phenomenon involving the stretch reflex.(ABSTRACT TRUNCATED AT 400 WORDS)
Women entering the Army are exposed to considerable physical stress due to the intense physical training program encoun tered. At the beginning of a basic training cycle, a prospective study was initiated to identify exercise-related injuries and performance-limiting conditions that resulted from an 8-week physical training program and to identify some of the factors that may contribute to their occurrence. Four hundred women recruits (age 18 to 29 years) participated in the study. All had passed an initial physical examination and were without any limiting disabilities. An initial assessment of physical fitness was accomplished to determine the current status of body composition, strength of the major muscle groups (e.g., legs, trunk, arms, and upper torso), aerobic capacity, previous ath letic history, self-perception of physical fitness, and psychoso matic predisposition. The training and conditioning program (1 hr daily, five to six times a week) involved a series of standard warm-up calisthenics and stretching exercises fol lowed by a run, beginning at 3/4 mile at a 10 min per mile pace and increasing to 2 miles at 9½ min per mile by the end of training. Extensive road marches and military training activities were also included. At the end of training, a self-report injury questionnaire was used to collect injury data. These data were documented with the records from the unit dispensary and data provided by the installation physical therapy, orthopaedic, and podiatry clinics. Fifty-four percent (215) of the women sustained some reportable injury. These injuries resulted in an average training time loss of 13 days. Forty-one percent of these injuries prevented participation in all activity, 31% resulted in only limited participation. Early training "overuse syndrome" ac counted for 42% (92) of the reported injuries. Significant injuries were: tibial stress fracture (45), chondromalacia of the patella (21), hip or neck of femur stress fracture (20), sprains (12), Achilles tendinitis (10), calcaneous or metatarsal stress fracture (8), and fascial and anterior compartment strains (6). The injury data were correlated with prior-fitness measures. The results indicated that a major cause of injury in women can be attributed to the lack of prior conditioning, greater body weight and fat percent, and limited leg strength. These factors, coupled with some inherent physiologic characteristics of women (i.e., wide pelvis, less strength, and greater joint flexi bility), probably contributed to the increased risk of injury in these women. It is concluded that susceptibility to these poten tial orthopaedic and medical conditions can be identified before the beginning of training and minimized through proper reme dial activity before a strenuous physical training program is initiated.
Stretching exercises are either performed alone or with other exercises as part of the athlete's warm-up. The warm-up is designed to increased muscle/tendon suppleness, stimulate blood flow to the periphery, increase body temperature, and enhance free, coordinated movement. The purpose of this paper is to review the literature regarding stretching, with the aim of defining its role during the warm-up. Implications of stretching on muscle/tendon flexibility, minimizing injury, enhancing athletic performance, and generally preparing the athlete for exercise are discussed. Physiology applied to stretching is also discussed together with different related techniques and practical aspects. A proposed model stretching regime is presented based on the literature reviewed.
Three hundred fifty male recruits were divided into two groups: Walk (N = 170) and Run (N = 180). A physical screen was performed before the commencement of recruit training consisting of a visual assessment of the feet looking for pes planus, pes cavus, and deformities of the toes. Each recruit was also asked if he had sustained any injury in the preceding 2 years. The visual findings and history of prior injury were noted and compared with actual injuries sustained during the 12-week training course. Fifty-three subjects in the Walk group and 54 in the Run group were identified as being at risk as a consequence of the screen. The sensitivity of the screen for predicting the subsequent injury was 34.4% in the Walk group and 31.8% in the Run group. The specificity was 72.6 and 77.4% in the Walk and Run groups, respectively. The predictive value of the test was 44.9% in the Walk group and 50.9% in the Run group. When reinjury was examined, the sensitivities fell to 9.4% (Walk) and 4.7% (Run) and the specificities to 57.5% (Walk) and 50.5% (Run). The screen correctly identified only 1 of 10 medical discharges in the Walk group and 2 of 16 in the Run group. The screening examination had poor sensitivity, specificity, and predictive value, and more than half of those thought to be at risk did not subsequently sustain an injury. Anecdotal beliefs that improvements in medical screening would reduce recruit wastage were not borne out. Abnormalities of the foot (pes planus, pes cavus, hallux valgus) were not significant factors in the development of injury during recruit training.
Randomized clinical trials analyzed by the intent-to-treat approach provide unbiased comparisons among treatment groups. To avoid dilution of treatment effect, many people also perform an analysis by treatment actually received, although this method may introduce bias into the results. This paper presents several approaches used for analyzing data of a recent trial and the difficulties encountered in interpreting the results of each approach. The ANRS 005/ACTG 154 Study was a double-blind, placebo-controlled, randomized, international (French, U.S., and Spanish) multicenter trial designed to assess the effectiveness of pyrimethamine for the primary prophylaxis of cerebral toxoplasmosis (CT) in HIV-infected patients with advanced immunodeficiency. In the intention-to-treat analysis, the cumulative probability of CT at 1 year did not differ significantly between the pyrimethamine arm (11.9%) and the placebo arm (13.1%), Hazard Ratio (HR) = 0.94 (95% Confidence Interval (CI) = 0.62-1.42), whereas an on-treatment analysis resulted in a significant difference: 4.2% in the pyrimethamine arm and 12.4% in the placebo arm, HR = 0.44 (95% CI = 0.24-0.80). The data showed a significant interaction between compliance and treatment outcome; and side effects were more frequently cited as reasons for compliance violations in the pyrimethamine group. Several different analytic approaches (censoring data at the time patients discontinued the study medication only for selected reasons) failed to explain the disparity between the estimation of effect of pyrimethamine by the intention-to-treat and on-treatment analyses. This experience led us to believe that comparing the results of both analyses was the best method to convince clinicians that intention-to-treat was the only interpretable analysis. We were concerned that even if pyrimethamine had a beneficial effect, it was very difficult (1) to quantify and (2) to apply to clinical practice unless one could predict the occurrence of study drug discontinuation for each patient at the time of treatment assignment. Although exploratory analyses may yield clinically relevant information and useful clarifications in the evaluation of treatments, intention-to-treat remains the only interpretable analysis of clinical trials.
This study investigated effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on relative risk of selected injuries in 1093 male Army recruits undertaking 12 weeks of intensive training. Prior to training, ankle dorsiflexion range was measured and recruits were allocated to stretch and control groups using a quasi-random procedure. The stretch group stretched calf muscles under supervision prior to all intense exercise. The control group stretched upper limb muscles instead. Forty-eight injuries were recorded. Survival analysis indicated that ankle dorsiflexion range was a