It is widely acknowledged that warming up before any vigorous activity is important, and research studies have shed light on the ways that different types of warm-up influence the vigorous activity that follows (7). The initial success of any daily training routine lies in its initiation, generally known as the pre-activity routine, and typically consists of general and specific warm-up periods. General warm-up periods typically consist of 5–10 minutes of jogging, arm swings, and other nonspecific forms of exercise designed to increase muscle temperature and blood flow. Specific warm-up periods also are generally 5–10 minutes in length and consist of sport-specific activity designed to prepare the athlete for the demands of the sport by increasing nerve-conduction velocity, decreasing muscle stiffness, and enhancing power (5,7,12,29). The overall goal of any pre-activity routine is to prepare athletes for practice or competition (7,26,31,36), and various forms of stretching are used in most programs.
The period after warm-up and vigorous physical activity is called the “cooldown,” or the posttraining period. Research indicates that periods of stretching can contribute to long-term changes in the elastic properties of the connective tissue within the muscle-tendon architecture, resulting in increased force production and contraction velocity (10,35,38). The benefits of pre- and post-activity are well accepted, but the purported value of stretching pre- and post-competition is certainly less clear (32). Stretching, as a form of exercise, can be separated into 4 categories: static stretching (SS), ballistic stretching (BS), proprioceptive neuromuscular facilitation (PNF), and dynamic stretching (DS) (16,25). Their selection depends on the individual who designs the training program and the desired performance outcomes.
A review of the literature on pre- and post-activity stretching shows that prevailing wisdom on “best practices” has changed substantially over the past 35 years (1). For instance, although SS was widely hailed in the early 1980s, more recent studies indicate that pre-activity SS can actually be detrimental to force and torque production or other measures of maximal gross motor performance (41). Although it has been suggested that some of these effects may be linked to changes in the connective tissue of the musculoskeletal system (43), it would seem that the negative effects of SS would have to involve neural mechanisms (6,13) that influence force and torque production. There is some evidence to suggest that SS can elicit an increase in parasympathetic activity within the central nervous system, which could affect neural tone and be undesirable for many maximal athletic endeavors (10,15). Conversely, DS has been shown to enhance performance by increasing the subsequent rate of force development (26,41). Unfortunately, no known position article currently exists on the “best practices” for integrating flexibility training into daily workout regimens. However, looking toward the goal of translating research into effective training and rehabilitation regimens, research studies regularly suggest that SS is detrimental, whereas DS often leads to more desirable outcomes when these forms of stretching are used before vigorous activity (16,24,44). One factor that has received little attention is the transient nature of stretching. A study by Torres et al. (43) compared SS and DS in the upper body. They found no difference between these stretches and suggested that the 5-minute rest period they used after stretching might have been responsible for the lack of effect.
In collegiate settings, coaches often develop pre- and post-activity stretching protocols based on their knowledge and experiences. Although there is a lot of research addressing stretching protocols, coaches do not always follow evidence-based guidelines (18,19,21–23). A pilot study by Judge et al. (21) indicated that football coaches use SS, PNF, and BS techniques in the pre-activity warm-up despite current research (35,38) indicating that the use of these techniques is not highly advisable. A related survey of tennis coaches (17) found that only half of the participating coaches implemented pre-activity flexibility training in accordance with contemporary research findings. Additionally, although most tennis and football coaches recommended postactivity stretching, they did not follow recommended guidelines (17,21).
Athletic trainers (ATs) are regularly involved in the development and/or supervision of the pre- and post-activity protocols widely used in all sports. Although strength and conditioning professionals (SCP) increasingly are responsible for the direct supervision of such pre- and post-activity protocols used in collegiate athletics, this emerging practice is far from consistent and may be more commonly seen at the Division I level, where universities typically have greater financial resources necessary to fund SCP. Athletic departments at many smaller universities and colleges do not retain SCP, thus they frequently rely on other strategies for regular implementation of pre- and post-activity protocols. As such, ATs are often involved with the pre- and post-activity protocols used within collegiate athletic programs, as are the sport-specific coaches and the SCP. Moreover, as the on-site member of the healthcare team, ATs typically supervise the pre- and post-activity regimens of athletes to ensure that athletes are doing what is necessary to prevent and/or recover from the various types of injuries.
Historically, physical educators, exercise-related professionals, coaches, and ATs were taught that SS was a necessary component of any pre-activity routine based on the belief that it decreases the incidence of musculoskeletal injuries. This view is based on the notion that SS increases the compliance of the muscle-tendon unit, allowing greater relative force production at longer muscle lengths in combination with increased ability to resist excessive muscle elongation, thus decreasing the susceptibility of a muscle strain (28). A debate has existed for decades regarding forms of warm-up and/or types of flexibility training and their role in injury prevention. This question remains today, although current evidence suggests that SS does not decrease the incidence of injury (2,9,28,36,37). Perhaps more importantly, although the question on the role of SS remains unanswered, it may cloud a related, but subtly different question for which there is much evidence: How does SS influence performance during gross motor performance which it precedes? Numerous studies indicate that decreased muscular force production, sprint times, vertical jump scores, and other performance measures are consistently demonstrated when these activities immediately follow SS (3,8,30). In short, although the neurological and mechanical contributions to such findings are still being studied more fully, the consistency of these results suggests that SS performed before activity is often detrimental to performance. It is less clear how professionals may be changing their training practices in light of such findings.
There is evidence to suggest that DS is preferable to SS before vigorous physical activity, and that SS does not prevent injury (2,16,26,28,36,37,41). There has also been evidence suggesting that, although coaches may use a variety of pre- and post-activity routines, the activities used are not always in line with current evidence (17–19,21–23). In sport settings, the AT is often the first member of the health care team to interact with athletes (29), and the AT is often asked by athletes and coaches to assist with pre-activity and post-activity stretching. For these reasons, it is important to know if ATs recommend training based on evidence-based research. At this time, however, little is known regarding (a) the knowledge of ATs because it relates to current research for pre-activity warm-up or (b) the pre- and post-activity stretching methods used by these members of the health care team working within collegiate athletic programs. Consequently, this population presents a unique opportunity to explore how information from recent research studies may or may not be translating into contemporary practices. The purpose of this study, then, was to investigate the knowledge and practices of collegiate ATs to determine to what extent stretching practices are in line with current research.
Experimental Approach to the Problem
The purpose of this study was to investigate the knowledge and practices of collegiate ATs in the United States, examining if these variables are in line with current research findings. A survey instrument allowed for data collection from institutions and ATs across all divisions of the target population. The survey instrument produced ample data regarding current practices, and the data were analyzed for differences amongst the demographic, educational, and institutional classifications. These characteristics were used to explore variables that could potentially describe how well contemporary practice aligns with current scientific understanding regarding stretching and flexibility training.
Athletic trainers who actively provided athletic care and were employed in collegiate settings at the time of the study were invited to participate. Eligible participants met the following inclusion criteria: certified by the Board of Certification and employed in any NCAA, NAIA, or junior college setting. A database was secured from the National Athletic Trainers' Association (NATA) of ATs who have a role in patient care, as indicated by their employment setting (college or university) and primary job title (e.g., AT, head AT, assistant AT, etc.). Using these criteria, a list of 2,839 ATs was generated. This study was approved by the Institutional Review Board at Ball State University, and completion of the survey instrument served as informed written consent for all participants.
Of the 2,839 ATs that were contacted, 521 responses were collected for a response rate of 18%, but only 500 individuals met all inclusion criteria and completed the survey in its entirety. Despite a low response rate, the participants represented all 10 NATA districts and all NCAA levels, NAIA, and junior colleges, giving us a fair representation of collegiate ATs in a multitude of locations and collegiate settings.
Demographic data (Table 1) indicate that the respondents were almost equally divided into males (50.2%) and females (49.6%), with 192 head ATs (38.4%) and 245 assistant ATs (47.0%) representing the bulk of participants. The 45 associate ATs (9%) and 18 graduate assistant ATs (3.6%) represented only a small portion of the total number of respondents. The experience level of the participants ranged from 1 to 5 years (26.2%, n = 131) to >20 years (17.0%, n = 85), with good representation of the years in between those extremes; 6–10 years (27.2%, n = 136), 11–15 years (18.8%, n = 94), and 16–20 years (10.8%, n = 54), although 253 (50.6%) of the respondents were between the ages of 26 and 35 years (Table 1). Of the respondents, 430 (82.5%) held at least a master's degree or above in athletic training (20%, n = 100), exercise science (22.4%, n = 112), or another related field (19.8%, n = 99). More than half of the respondents (64.4%, n = 322) had an undergraduate degree in athletic training.
The “pre- and post-activity stretching practices in athletic training questionnaire,” a web-based survey instrument housed on Survey Monkey (https://www.surveymonkey.com), was used for data collection. The survey instrument consisted of 5 sections: demographic characteristics, pre-activity general warm-up practices, pre-activity stretching practices, post-activity cooldown practices, and post-activity stretching practices. As with previous research (21,22), an item analysis of the questionnaire was calculated using the Cronbach coefficient α, and revealed acceptable internal consistency, α = 0.722.
Pre-activity was defined in the survey instrument as before athletic participation, which may include training/conditioning, team practices, or competitions. The questions related to pre-activity practices were designed to assess the knowledge and practice of ATs regarding pre-activity warm-up and stretching routines, duration of the routines, type of techniques performed, and compliance of the athletes in completing these activities. Similarly, items in the post-activity sections, defined as after athletic participation, which may include training/conditioning, team practices, or competitions, included similar items to assess the knowledge and practices of ATs.
The NATA was contacted to request a membership list containing information regarding members (a) who met the inclusion criteria of working in “university & college” settings and (b) with job titles indicating they were likely directly involved with the care of athletes (e.g., “head athletic trainer,” “associate/assistant athletic trainer,” and “athletic trainer”), resulting in a list of 2,839 individuals. An e-mail, describing the purpose of the study, a brief description of the survey, and a description of how consent was obtained, was sent requesting participation. Participants were instructed to click on a website URL where they could complete the online survey.
Two weeks after the initial solicitation, a second e-mail was sent to all potential participants. The second e-mail included a disclaimer requesting those who had already completed the survey ignore the follow-up solicitation. The investigation consisted of 4 weeks of data collection with 2 solicitations.
All responses for the questionnaire were collected through Survey Monkey and downloaded into an Excel 2010 (version 14; Microsoft Corporation, Redmond, WA) spreadsheet. Descriptive statistics including frequency distributions were collected for the demographic and 4 other sections of the questionnaire. Pearson chi-square was used to assess reported perception and practices by descriptive categories. Furthermore, kappa values were established to determine interpersonal agreement between items. The α level was set a priori at 0.05. Data were analyzed using IBM SPSS Statistics (version 20.0; SPSS Inc., Chicago, IL).
A majority of respondents (99.4%, n = 496) recommended athletes perform a general warm-up before physical activity, and more than a third (38.4%, n = 189) recommended the specific warm-up consist of sport-specific drills. There is a moderate level of agreement (κ = 0.550, p < 0.001) between the ATs who recommended sport-specific drills (31.6%) within the pre-activity warm-up routine and their observation that the athletes actually perform them during the pre-activity warm-up. A large percentage (84.5%, n = 402) of respondents recommended that athletes perform pre-activity stretching. There was an age difference between respondents recommending versus not recommending pre-activity stretching. A significantly higher percentage (χ2 = 12.877, p = 0.025) of ATs older than 40 years (86%) recommended athletes perform pre-activity stretching, when compared with respondents under 40 years (73%). About one-third (32.2%, n = 170) of the 402 respondents who recommended pre-activity stretching specified DS (Figure 1). A small percentage of ATs (28%, n = 117) indicated that athletes under their care were performing DS (Figure 1), whereas more (54.1%, n = 226) reported that a combination of SS and DS stretching was used pre-activity. There is a moderate level of agreement (κ = 0.582, p < 0.001) between the ATs (21.0%) who recommended pre-activity DS and their observation that the athletes actually performed DS pre-activity. In addition to whole-team warm-up activities, 91.9% (n = 432) of the ATs responded that they assist athletes individually with additional stretching before activity, using a variety of methods (Figure 2). Most respondents (92.4%, n = 425) indicated that pre-activity stretching was an area athletes could improve on. Also, a significantly higher percentage (χ2 = 11.982, p = 0.035) of ATs under 40 (19%) reported using PNF stretching when compared with the percentage of those over 40 (7%) who use this method.
A majority of respondents (88.7%, n = 407) recommended a general cooldown routine, with roughly half (49.9%, n = 201) indicating it should last 6–10 minutes immediately after physical activity. More than half (52.6%, n = 212) recommended jogging as the preferred method to accomplish the cooldown. However, respondents indicated that a cooldown routine actually occurs only 50% (n = 227) of the time. The majority of ATs (89.5%, n = 402) recommended that athletes perform a post-activity stretching protocol, with most (60.6%, n = 241) indicating that SS be performed (Figure 1) for a duration lasting 6 to 10 minutes (59.3%, n = 236). The data also show that ATs aged 26–40 years, and those with 1–15 years of experience, recommended postexercise SS significantly more often (χ2 = 18.2, p = 0.029, and χ2 = 12.8, p = 0.012, respectively) than ATs who were older and more experienced. Interestingly, only 57.8% (n = 257) of ATs reported their athletes performed a postactivity stretching protocol, indicating this stretching consisted of SS in most instances (69.4%, n = 177). Data regarding postactivity produced a significant level of agreement (κ = 0.761, p < 0.001) between the ATs (61.0%) who recommended SS postactivity and their reports of the athletes actually performing SS. Similar to pre-activity responses, 68.8% (n = 305) of the ATs who assisted their athletes with additional stretching postactivity used SS (63.8%, n = 94), and it lasted 5 minutes or less (65.5%, n = 199). Most ATs (95.2%, n = 419) indicated that postactivity stretching is an area that athletes could improve.
Finally, a majority of the respondents reported that both pre- and post-activity stretching will increase performance (81.3, 75.7%, respectively; Figure 3) and help to prevent injuries (87.8, 88.6%, respectively). Most respondents (95.9%, n = 441) also indicated that overall flexibility is an area for improvement in athletes.
The first consideration for any exercise session is to determine the most effective way to prepare the athlete for the activity. The exercise science literature recommendations for pre-activity warm-up (7,14,25,39,42) include a general warm-up and sport-specific warm-up (12,25,30). After training or competition, the athletes are encouraged to perform a cooldown routine that includes postactivity stretching (30).
Concurrent with the literature, 99.4% of ATs in this study recommended that athletes complete a pre-activity warm-up. These findings are similar to previous studies by Judge et al. (18,21), which revealed that 100% of the college football programs (21) and women's college volleyball programs (18) surveyed performed a pre-activity warm-up. Interestingly, 91.9% (n = 441) of ATs reported that the pre-activity warm-up routine is an area in need of improvement but only 38.4% (n = 189) recommended pre-activity warm-up consist of sport-specific drills. Without proper activation, the muscles needed for athletic performance cannot perform optimally. Although participants indicated an awareness of phenomenon in their support of pre-activity warm-up, their response suggests that they are either unfamiliar with current research on sport-specific warm-up, choose not to integrate this information into their practice patterns, or encounter resistance within athletic departments when they espouse such changes to pre- and post-activity regimens. Unfortunately, this study provides no evidence to determine why such a low percentage of ATs follow current research recommendations.
One of the primary components of proper muscle function is extensibility, or the capacity of muscle to lengthen, and 84.5% (n = 402) of the respondents reported that they instruct their athletes to perform pre-activity stretching. Current research indicates that DS before activity is more beneficial than SS, PNF, or BS (4,7,11,25,39–42). However, only 32.2% (n = 170) of ATs in this study recommended DS, with just under half of them (42.2%) recommending a combination of SS and DS activities (n = 223). When describing the type of pre-activity stretching protocol actually performed by athletes, ATs responded that only 28.0% (n = 117) of athletes in their athletic programs are performing DS, whereas 54.1% (n = 226) indicated that their athletes use a combination of SS and DS during pre-activity. The present findings correspond to data reported by Judge et al. (21), in which 87% of the respondents used some form of pre-activity stretching but only 30% of those respondents used DS exclusively. Again, the present findings suggest that ATs may either be unfamiliar with contemporary research findings, choose not to integrate such information into their practice patterns, or encountered roadblocks within the athletic department that limit their ability to implement such information. Although the negative effects of pre-activity SS have been reported (25,27), most research on pre-activity stretching has tested only a single bout of SS before the specific activity and has not measured the effects of the time an SS is held or the rest period between the stretch and testing. This presents limitations when generalizing findings to the design of training programs, and consequently more research is needed on the combination of stretching and other sport-specific activities typically used in a warm-up.
The present findings revealed that respondents were hesitant to eliminate pre-activity SS. This hesitancy may be linked to their reluctance to remove SS protocols they learned from their own training experience (21). In a related study of high school coaches, personal experience and scientific evidence were the 2 factors that coaches said would most likely influence their future recommendations regarding pre-activity stretching (33). Given that SS is a traditional warm-up practice, suddenly eliminating this element might have a negative psychological effect on some players, especially if they have a history of using it and maintain a belief in its benefits (43). Another factor may be related to the pressures—real or imagined—felt by ATs to follow the protocol prescribed by the coach or to meet the needs of the athlete who feels comfortable with SS. Whether real or imagined, such roadblocks may impede the capacity of ATs to foster advancement of pre-activity regimens used within a collegiate setting. Lastly, the practicality of issuing clear instructions regarding technique, volume, and intensity of stretching exercise may be difficult to supervise adequately, especially with large numbers of athletes, as in team sports like football (43).
Athletic trainers report practices in line with current research, recommending that postactivity include a cooldown routine and SS (34). Interestingly, 48.2% of ATs report that athletes complete a postactivity stretching protocol less than half of the time. The majority (89.5%, n = 402) of ATs recommended that athletes perform a stretching protocol postactivity, with most (60.6%, n = 241) indicating that SS be performed and the routine last between 6 and 10 minutes (59.3%, n = 236). Remarkably, only 57.8% (n = 257) of ATs reported that the athletes under their care performed a postactivity stretching protocol, and the stretching consisted of SS in the majority of cases (69.4%, n = 177). This finding is greater than the 43.5% of football coaches who reported that athletes do not complete any postactivity stretching protocol (21), but comparable with postactivity flexibility practices reported by volleyball coaches who indicated that athletes perform a postactivity stretching protocol 71.4% of the time (18). These findings suggest ATs are reporting postactivity practices in agreement with previous research reports.
The majority of ATs indicated that pre-activity group stretching was beneficial in terms of injury prevention (87.8%) and improved performance (81.3%). Similarly, ATs indicated that postactivity group stretching was beneficial in terms of injury prevention (88.6%) and improved performance (75.7%). However, current research does not fully support these views. Many studies suggest SS limits performance when performed before vigorous activity, and the role of stretching in injury prevention is inconclusive (2,28,36,37). Therefore, it seems that ATs may not be reviewing current research findings, not choosing to use it, or a combination of both.
To better understand the disconnect between the present findings and recent research reports, it is helpful to know where ATs obtain information regarding pre- and post-activity routines. The largest percentage (61.5%) reported their source of information was media, including journals, books, videos, and online resources. With such a wide array of sources for information, an AT could easily use information that is not evidence-based. However, a larger percentage of ATs (65%) indicated that continuing education program was their primary source of information. Unfortunately, the survey instrument of this study did not contain questions designed to understand how ATs use educational sources or how they reconcile existing practice patterns in light of new information. Indeed, some researchers have identified the inability of practitioners to appropriately evaluate peer-reviewed research that is presented to them as the reason they may cling to long-held yet erroneous views (20). The ability to use research finding must be based on not only reviewing the available literature but also appraising the quality of the evidence. This is a skill that not all ATs may possess, which could explain why they are not willing to test research-based training techniques. Additional study is needed to better understand (a) the veracity of information presented in continuing education seminars and (b) how professionals reconcile and integrate new evidence-based information into their clinical practice patterns. Similarly, acknowledging that ATs typically do not wield complete control over the pre- and post-activity regimens used in any collegiate athletic setting given, in particular, the necessary presence of sport-specific coaches and SCP, it would likely be beneficial to explore “interdisciplinary” dynamics that may presently create roadblocks for ATs (and other exercise professionals) who want to foster change in training regimens used within collegiate athletics.
The present findings suggest that experience and age were significantly related to the use of evidence-based practices. Athletic trainers between the ages of 26 and 40 years and possessing the least experience (1–15 years) reported a higher use of postactivity SS than those who were older and more experienced. In a similar study (33), the pre- and post-activity stretching practices of Division I and Division III football coaches were evaluated, and the results indicated that only 3% of the coaches (n = 21) participating in the survey use DS exclusively before training or competition and were in the youngest age category (younger than 36 years). In other words, the coaches with the greatest experience were more likely to operate against evidence-based practices, using a combination of SS, DS, and PNF before practice.
In summary, the goal of this study was to examine practices of collegiate ATs because it pertains to knowledge and current practices for pre-activity warm-up and postactivity cooldown, respectively. The present findings indicate that less than half of collegiate ATs seem to prescribe pre-activity stretching protocols in line with recent research findings. The disconnect between current research and contemporary practice is particularly evident, because it relates to differences between DS and SS and their residual effects on force generation, which follows these forms of stretching. This study adds to the literature by reporting the knowledge and practices of ATs working in collegiate settings. These findings corroborate previous reports on coaches in a variety of sports who also do not fully link current stretching research findings to their practice plans (18,19,21–23).
In most sport settings, the AT is often the first member of the health care team who interacts with athletes. The results of this study, in conjunction with studies examining coaching practices (17,19,22), indicate that ATs and sport coaches may be having difficulty keeping abreast of current research and integrating it into training programs for their athletes. Although recent research supports DS over other forms of pre-activity protocols (27,41), it seems that some ATs may be unaware of this research or reluctant to completely discontinue traditional stretching methods. They may also encounter outright resistance from within the athletic department when they propose changes to existing practices such as pre-activity SS. The present findings suggest that ATs might consider broader implementation of pre-activity DS shown through research studies to boost athletic performance (23). Athletic trainers clearly have limited control over many practices that regularly occur within any collegiate athletic department, and this limited authority extends to matters such as pre- and post-activity regimens. Strength and conditioning professionals and sport-specific coaches also have a hand in such practices, and ATs should partner with them to determine what is best for the athlete. Therefore, the present findings may assist ATs (and other exercise professionals) in fostering a dialogue within their respective athletic department toward the goals of providing the best possible exercise and athletic preparation programs.
1. Anderson B. Conditioning report: Stretching for football. Natl Strength Coach Assoc J 2: 14–18, 1980.
2. Andersen JC. Stretching before and after exercise: Effect on muscle soreness and injury risk. J Athl Train 40: 218–220, 2005.
3. Bacurau RFP, Monteiro GA, Ugrinowitsch C, Tricoli V, Cabral LF, Aoki MS. Acute effect of a ballistic and a static stretching exercise bout on flexibility and maximal strength. J Strength Cond Res 23: 304–308, 2009.
4. Bazett-Jones DM, Gibson MH, McBride JM. Sprint and vertical jump performances are not affected by six weeks of static hamstring stretching. J Strength Cond Res 22: 25–31, 2008.
5. Behm DG, Button DC, Butt JC. Factors effecting force loss with prolonged stretching. Can J Appl Physiol 26: 262–272, 2001.
6. Behm DG, Peach A, Maddigan M, Aboodarda SJ, DiSanto MC, Button DC, Maffiuletti NA. Massage and stretching reduce spinal reflex excitability without affecting twitch contractile properties. J Electromyogr Kinesiol 23: 1215–1221, 2013.
7. Cè E, Margonato V, Casasco M, Veicsteinas A. Effects of stretching on maximal anaerobic power: The roles of active and passive warm-ups. J Strength Cond Res 22: 794–800, 2008.
8. Cramer JT, Housh TJ, Weir JP, Johnson GO, Coburn JW, Beck TW. The acute effects of static stretching on peak torque, mean power output, electromyography, and mechanomyography. Eur J Appl Physiol 93: 530–539, 2005.
9. Cross KM, Worrell TW. Effects of a static stretch program on the incidence of lower extremity musculotendinous strains. J Athl Train 34: 11–14, 1999.
10. Farinatti PTV, Brandão C, Soares PPS, Duarte AFA. Acute effects of stretching exercise on the heart rate variability in subjects with low flexibility levels. J Strength Cond Res 25: 1579–1585, 2011.
11. Fredrick G, Szymanski D. Baseball (part I): Dynamic flexibility. Strength Cond J 23: 21–30, 2001.
12. Fry AC, McLellan E, Weiss LW, Rosato ED. The effects of static stretching on power and velocity during the bench press exercise. Med Sci Sports Exerc 35: S264, 2003.
13. Gergley JC. Acute effects of passive static stretching during warm-up
on driver club head speed, distance, accuracy, and consistent ball contact in young male competitive golfers. J Strength Cond Res 23: 863–867, 2009.
14. Hedrick A. Physiological responses to warm-up
. Natl Coach Assoc J 14: 25–27, 1992.
15. Hotta K, Kamiya K, Shimizu R, Yokoyama M, Nakamura-Ogura M, Tabata M, Masuda T. Stretching exercises enhance vascular endothelial function and improve peripheral circulation in patients with acute myocardial infarction. Int Heart J 54: 59–63, 2013.
16. Hunter JP, Marshall RN. Effects of power and flexibility training on vertical jump technique. Med Sci Sports Exerc 34: 478–486, 1992.
17. Judge LW, Bellar D, Craig B, Petersen J, Camorata J, Wanless E, Bodey K. An examination of the pre-activity and post-activity stretching practices of division I college tennis coaches. J Strength Cond Res 26: 184–191, 2012.
18. Judge LW, Bodey K, Bellar D, Bottone A, Wanless E. Pre-activity and post-activity stretching perceptions and practices in NCAA division I volleyball programs. ICHPERD SD J Res 5: 68–75, 2010.
19. Judge LW, Bodey K, Bellar D, Craig B, Prichard M, Wanless E. An examination of the pre-activity and post-activity stretching practices of NCAA division I and NCAA division III college basketball programs. J Coach Edu 4: 46–64, 2011.
20. Judge LW, Craig B. The disconnect between research and current coaching practices. Strength Cond J 36: 46–51, 2014.
21. Judge LW, Craig B, Baudendistal S, Bodey KJ. An examination of the stretching practices of division I and division III college football programs in the Midwestern United States. J Strength Cond Res 23: 1091–1096, 2009.
22. Judge LW, Petersen J, Bellar D, Craig B, Wanless E, Benner M, Simon L. An examination of the pre-activity and post-activity stretching practices of division I college track and field distance coaches. J Strength Cond Res 2012: 2456–2464, 2013.
23. Judge LW, Wildeman J, Bellar D. Designing effective pre-activity warm-up
routine for the 1 RM back squat. Strength Cond J 33: 88–90, 2011.
24. Kistler BM, Walsh MS, Horn TS, Cox RH. The acute effects of static stretching on the sprint performance of collegiate men in the 60- and 100-m dash after a dynamic warm-up
. J Strength Cond Res 24: 2280–2284, 2010.
25. Kruse NT, Barr MW, Gilders RM, Kushnick MR, Rana SR. Using a practical approach for determining the most effective stretching strategy in female college division I volleyball players. J Strength Cond Res 27: 3060–3067, 2013.
26. LaRoche DP, Lussier MV, Roy SJ. Chronic stretching and voluntary muscle force. J Strength Cond Res 22: 589–596, 2008.
27. Little T, Williams A. Effects of differential stretching protocols during warm-ups on high-speed motor capacities in professional soccer players. J Strength Cond Res 20: 203–207, 2006.
28. Mann D, Whedon C. Functional stretching: Implementing a dynamic stretching program. Athlet Ther Today 6: 10–13, 2001.
29. McHugh MP, Cosgrove CH. To stretch or not to stretch: The role of stretching in injury prevention. Scand J Med Sci Sports 20: 169–181, 2010.
30. Nelson A, Kokkonen J, Arnall D. Acute muscle stretching inhibits muscle strength endurance performance. J Strength Cond Res 19: 338–343, 2005.
31. Nelson RT, Brandy WD. An update on flexibility. Strength Cond J 27: 10–16, 2008.
32. Rey E, Lago-Peñas C, Casáis L, Lago-Ballesteros J. The effect of immediate post-training active and passive recovery interventions on anaerobic performance and lower limb flexibility in professional soccer players. J Hum Kinet 31: 121–129, 2012.
33. Ryan ED, Beck TW, Herda DJ, Hull HR, Hartman MJ, Stout JR, Cramer JT. Do practical durations of stretching alter muscle strength? A dose response study. Med Sci Sports Exerc 40: 1529–1537, 2008.
34. Ryan ED, Everett KL, Smith DB, Pollner C, Thompson BJ, Sobolewski EJ, Fiddler RE. Acute effects of different volumes of dynamic stretching on vertical jump performance, flexibility and muscular endurance. Clin Physiol Funct Imaging 34: 485–492, 2014.
35. Safran MR, Garrett WE Jr, Seaber AV, Glisson RR, Ribbeck BM. The role of warmup in muscular injury prevention. Am J Sports Med 16: 123–129, 1988.
36. Sharman MJ, Cresswell AG, Riek S. Proprioceptive neuromuscular facilitation stretching: Mechanisms and clinical implications. Sports Med 36: 929–939, 2006.
37. Shrier I. Stretching before exercise does not reduce the risk of local muscle injury: A critical review of the clinical and basic science literature. Clin J Sport Med 9: 221–227, 1999.
38. Shrier I. Does stretching improve performance? A systematic and critical review of literature. Clin J Sport Med 14: 267–273, 2004.
39. Siatras TA, Mittas VP, Maneletzi DN, Vamvakoudis EA. Peak torque production. J Strength Cond Res 22: 40–46, 2008.
40. Simic L, Sarabon N, Markovic G. Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scand J Med Sci Sport 23: 131–148, 2013.
41. Small K, Mc Naughton L. A systematic review into efficacy of static stretching as a part of a warm-up
for the prevention of exercise-related injury. Res Sports Med 16: 213–231, 2008.
42. Taylor KL, Sheppard JM, Lee H, Plummer N. Negative effect of static stretching restored when combined with a sport specific warm-up
component. Med Sci Sports Exerc 12: 657–661, 2009.
43. Torres EM, Kraemer WJ, Vingren JL, Volek JS, Hatfield DL, Spiering BA, Maresh CM. Effects of stretching on upper-body muscular performance. J Strength Cond Res 22: 1279–1285, 2008.
44. Winchester JB, Nelson AG, Landin D, Young MA, Schexnayder IC. Static stretching impairs sprint performance in collegiate track and field athletes. J Strength Cond Res 22: 13–19, 2008.