Adequate Preseason Conditioning
Although the majority of athletes met the criteria for each component of preseason conditioning (59% for aerobic conditioning, 62% for stretching, and 63% for strengthening), only 33% had adequate preseason conditioning, as defined by meeting the criteria on all three required components. Seventy percent of the athletes meeting the summary criteria reported more than 6 wk of preseason conditioning in preparation for the spring sports season. Of the remaining athletes, 15% did between 1 and 3 wk of conditioning, and 15% did between 4 and 5 wk. There was no significant association between adequate preseason conditioning and BMI category, grade level in school, type of spring sport, gender, first time playing, and winter sport participation. Adequate preseason conditioning was associated with being a varsity athlete (PR = 1.5, 95% CI 1.0-2.1) and receiving help with conditioning (PR = 1.7, 95% CI 1.1-2.7) (Table 3). Athletes most frequently reported a coach or friend as a source of help with conditioning, followed by a teammate, parent, or physical education (PE) teacher, respectively. Athletes who received help from a coach or PE teacher were most likely to have adequate preseason conditioning compared with those athletes who received help from other sources. Receiving help from a parent or teammate was also significantly associated with adequate preseason conditioning.
Aerobic Conditioning, Stretching, Strengthening Components
The pattern of factors associated with each component of conditioning differed from that for the summary preseason conditioning in three characteristics of interest: gender, winter sports participation, and first time playing a high school sport. BMI category, grade level, and type of spring sport were not associated with meeting criteria for each component. As in the summary preseason conditioning analysis, varsity athletes and athletes who received help with conditioning were more likely to meet criteria for the individual components. Of particular interest, winter sport athletes were more likely to meet the aerobic conditioning criteria than non-winter sport athletes (70 vs 55%, PR 1.1, 95% CI 1.0-1.3). Females were less likely to meet aerobic conditioning criteria than males (48 vs 65%, PR 0.7, 95% CI 0.6-0.8), and first-time high school athletes were less likely to meet aerobic conditioning criteria than experienced high school athletes (35 vs 63%, PR 0.6, 95% CI 0.4-0.9). Compared with males, females were more likely to meet the criteria for stretching days (71 vs 58%, PR 1.1, 95% CI 1.0-1.3) and were less likely to meet the criteria for strengthening days (58 vs 66%, PR 0.8, 95% CI 0.7-1.0).
On average, athletes participated in aerobic conditioning approximately 90 min·d−1 for 4 d·wk−1, totaling 6 h·wk−1 of aerobic physical activity (Table 4). Athletes typically did 3 d·wk−1 each of stretching and strengthening exercises.
This study demonstrates that the majority of high school athletes in this study population and setting do not participate in all of the recommended components of a preseason conditioning program before starting a competitive sports season. Varsity athletes and those who received help with conditioning, especially if it was from a coach or PE teacher, had a higher probability of participating in increased levels of preseason conditioning. Female athletes and first-time high school athletes participated in less aerobic conditioning than males and experienced athletes. Females were less likely to meet criteria for adequate strengthening but were more likely to meet criteria for adequate stretching. The majority of athletes did not participate in a winter school sport as a source preseason physical activity. The results may be useful for athletes, coaches, certified athletic trainers, certified strength and conditioning specialists, and school sports administrators.
Much of the prior research on physical conditioning has focused on general physical activity in all adolescents, without specifically focusing on high school athletes. Past findings from the Youth Risk Behavior Survey (YRBS) have shown that 65% of high school students participate in vigorous physical activity for at least 20 min on three or more days per week, as defined by the Healthy People 2010 goals for adolescent physical activity (16,18,33). If those national results apply to this study setting, the results of this study suggest that the majority of competitive high school athletes had at least as much vigorous aerobic exercise as that of the U.S. high school student population. We found that female athletes were less likely to participate in the aerobic conditioning component of preseason conditioning. This may be explained by the findings of several studies noting that adolescent females engage in less aerobic physical activity in general (3,16,17). We also found that junior varsity and inexperienced first-time high school athletes were less likely to participate in preseason conditioning. We hypothesize that these athletes may not understand the importance of engaging in adequate preseason conditioning before a competitive sports season.
The important question remains as to whether preseason conditioning is effective in reducing the risk of athletic injury. There is consistent expert opinion that children and adolescents should engage in gradual, progressive, age- and developmentally appropriate general fitness conditioning in addition to sport-specific skill training to prevent injury, particularly chronic overuse or repetitive strain injuries (9,15,21,26,29). There have been few epidemiologic studies and no randomized controlled injury-prevention trials in youth to support this position. On the basis of a review of past studies, Emery (12) concluded that deficits in endurance or strength attributable to limited preseason training may be associated with higher rates of injury in adolescents and adults. The majority of this past research involved an intervention designed to prevent injury in a specific sport. Additionally, these prior studies have significant limitations including inadequate control for confounders, nonrandom assignment of the intervention, lack of a control group, and broad intervention programs that do not allow preventive components to be addressed individually (11,12). Research in military populations provides the best evidence that level of physical fitness is a predictor of injury. Low levels of aerobic fitness and muscular endurance among military recruits (especially women) entering basic training have been shown to be strongly associated with training-related injuries (6,19). Conditioning programs instituted for unfit recruits before entering basic training have decreased the rate of attrition from basic training attributable to musculoskeletal injury (24). Although stretching is recommended as a component of preseason conditioning programs, there currently is little evidence that stretching prevents injury (32).
Several limitations of our study exist. The participating schools were not a random sample from a defined population of schools and were all large urban, public schools. Selection bias is possible, and results may not be generalizable to other settings, sports, or years. An important limitation is the retrospective rather than prospective self-report of activity. There are possible recall errors because athletes were asked to recall information about activities in which they had participated 1 month before the start of the sports season. However, it was not possible to directly measure or to observe the preseason physical activities for all participating athletes. Several studies have demonstrated self-report to be a valid measure of vigorous physical activity, and in addition, subjects tend to overreport rather than underreport their amount of physical activity (10,22,28). Although a portion of this survey used validated physical activity questions, the survey in its entirety was not revalidated. Spring school sport athletes may have achieved preseason conditioning by playing a school sport the previous season. We considered winter sport participation, not fall sport participation, to be the functional equivalent of preseason conditioning for a spring sport. We believe that potential misclassification of this prior sport participation could lead to either overestimation or underestimation of the true prevalence of preseason conditioning in this study. The physical activity that the athletes reported did not provide details on increases in volume and intensity over the course of the month or on sport-specific training, such as mileage per week for track athletes. The criteria for "adequate" preseason conditioning were adapted from the ACSM position statement on fitness for healthy adults; these criteria represent expert opinion and not an evidence-based standard. We acknowledge that aerobic conditioning, muscular stretching, and strengthening represent the minimum in terms of preseason conditioning. The results, which show that relatively few athletes fit even this minimum standard, are therefore conservative. A preseason program of sport-specific functional training is likely more beneficial and warrants further investigation. Lastly, because this is a cross-sectional study, there may be residual unmeasured confounding.
Although it is not possible from this study to determine the effectiveness of specific interventions to improve preseason conditioning or the amount of preseason conditioning needed to reduce injury risk, the results suggest that school- and coach-sponsored preseason conditioning programs may be more effective in achieving higher levels of preseason conditioning among high school athletes. Whereas most state high school athletic associations have rules governing when coaches can officially start practice for a sports season, schools can likely find other means to offer preseason conditioning to help their competitive athletes. All of the study schools employed a part-time certified athletic trainer, but none were available daily to student athletes. There may be a need for schools to provide better access to certified athletic trainers to improve participation in organized preseason conditioning programs and as part of a comprehensive injury-prevention program. It may be useful to educate coaches, parents, and athletes about the need for and importance of preseason conditioning and age-appropriate training as part of participation in competitive athletics. More specifically, it may be possible for coaches to promote athletics as a means for adolescents to learn about and engage in general fitness training that will lead to increased lifelong physical activity (31). Specific interventions might be targeted at those groups that are most at risk of not participating in adequate preseason conditioning-namely, female, junior varsity, and first-time high school athletes. An ideal time to start these interventions may be at the middle school level before entering the demands of competitive high school athletics. Future research should include injury-surveillance studies that examine the association between preseason conditioning and injury rates throughout the course of a season.
This work was presented in part as a poster at the American Medical Society for Sports Medicine Annual Meeting, May 1, 2006 and the American College of Sports Medicine Annual Meeting, June 1, 2006.
This work was supported by the Robert Wood Johnson Foundation and its Clinical Scholars Program (Dr. Brooks). The opinions are those of the authors and not the Robert Wood Johnson Foundation. We would especially like to thank Allen Cheadle, PhD for his thoughtful discourse and statistical support, and the Seattle-area high school administrators, coaches, parents, and athletes whose cooperation made this study possible.
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Keywords:©2007The American College of Sports Medicine
TRAINING; AEROBIC; STRETCHING; STRENGTHENING; ADOLESCENTS; ATHLETICS