Authors: Shawn M Mitchell, John C. Higginbotham, Mark T. Richardson, Jonathan E Wingo, Randi J Henderson Mitchell, Stuart L. Usdan
Corresponding Author:
Shawn Michael Mitchell, PhD, MA, MS, NSCA-CSCS
The University of Montevallo
Department of Exercise and Nutrition Science
108 Myrick Hall, Station 6591
Montevallo, AL 351115
smitche7@montevallo.edu
205-665-691
Shawn Mitchell is an assistant professor of exercise and nutrition science at the University of Montevallo in Montevallo, AL. His research interests include recovery from high intensity intermittent exercise, concurrent training, and exercise trainig techniques targeted at improvement in cycling performance. He is also a Certified Strength and Conditioning Specialist through the National Strength and Conditioning Association.
Resistance Training Among Competitive Mountain Bikers and Adherence to Recommended Training Guidelines
ABSTRACT
The sport of mountain biking provides an ideal avenue for examining sport specific training. Research has identified mainstays in mountain bike performance, which include peak power output (PPO) and mean power output (MPO). Resistance Training (RT) has been shown to increase muscular strength. An increase in strength can increase power output (PO). Increases in power would allow an athlete to perform at higher given workloads. A stronger individual will typically produce greater sustained PO, thereby increasing sport performance. The purposes of this study were to identify the prevalence of RT among competitive mountain bikers, as well as to determine if riders are adhering to the recommended guidelines shown to increase sport performance. Forty competitive mountain bikers responded to a nationwide online training survey assessing exercise training. Fifty-five percent of respondents reported participating in RT during the in-season. Mean number of workout sessions per week devoted to RT was 3.0 ± 1.2 days per week. Fifty-two and a half percent of respondents reported participating in RT during the off-season. Mean number of workout sessions per week devoted to RT was 2.8 ± 1.1 days per week. No significant difference (t = 0.8, df = 15, p = 0.4) in the number of workout sessions per week between seasons was shown. Results suggest that riders are adhering to the recommended resistance training guidelines associated with increases in sport performance. To increase performance, competitive mountain bikers should consider implementing RT into his or her workout regimen.
Keywords: off-road cycling, performance, strength, power, endurance, mountain biking
INTRODUCTION
The popularity of mountain biking as a recreational and competitive activity has steadily increased since its inception in the 1970’s (16, 37), and within the sport, two disciplines have received the bulk of attention in the peer-reviewed literature (1, 5, 11, 16, 17, 26, 32, 37). The first, cross-country (XC), incorporates elements of muscular power and endurance, as rides often demand the navigation of uphill and downhill technical off-road terrain. Typical XC races can last between 1-3 hours in duration (11, 16, 17, 26, 32, 37). In a similar manner, downhill riding (DH) also incorporates muscular power to navigate off-road terrain during a typical race. However, as opposed to XC events, DH riders will experience a greater vertical decent while reaching high speeds during a race (14). A typical DH race can last between 2-3 minutes (14, 15).
Based on these event durations, the demands on the three energy systems may vary; however, both disciplines rely on adequate force production to optimize performance during race based events (11, 14, 16, 37). Due to the nature of cycling, there is a great demand on lower body muscle fiber recruitment throughout the duration of a riding event (15). However, regardless of the discipline, riders must navigate technical off-road terrain, which requires a component of muscular endurance to provide body stability and balance. There also appears to be a large demand on the muscles of the upper body to generate substantial force during a typical XC or DH race (15). Furthermore, both mean power output (MPO) and peak power output (PPO), which are associated with muscular force production, have been shown as mainstays in successful XC riding performance (1, 5, 11, 16, 17, 26). Conversely, Hurst & Atkins (14) demonstrated that PPO was not shown to be related to DH riding performance; nonetheless, DH riders exhibited moderate power outputs (PO) during a race. Therefore, these authors recognized the need for DH riders to spontaneously generate high levels of power, especially at the start of a race. Thus, there appears to be a need for power development in both XC and DH riders.
To increase muscular power, riders may participate in resistance (RT), which has been credited as an optimal modality to increase muscular power, strength, and endurance (13, 24, 25, 28, 39). Power is defined as work divided by time, and muscular power is a function of speed of movement and muscular strength. An increase in strength will increase PO by increasing the velocity and force with which a muscle contracts. Thus, increases in strength resulting from RT should translate into increases in muscular power and force production (10, 19-21, 29, 31, 45). In fact, research has recognized that there is an overlap in the prescribed number of repetitions between training for strength versus training for power (7, 8, 22, 25). Additionally, high volume RT has been shown to increase muscular endurance, and muscular endurance has been shown to be associated with low to moderate PO production (8, 23, 24, 41).
Despite the benefits of RT for developing muscular strength, power, and endurance, the extent to which competitive mountain bike riders do, in fact, engage in RT to increase riding performance is unclear. Moreover, for those who do RT, it is unclear to what extent they are following training recommendations from reliable research-based sources (4, 8, 12, 22). Therefore, the primary purpose of this study was to determine the extent to which mountain bike riders do, indeed, engage in RT to increase performance. Additionally, this study sought to determine if riders follow RT guidelines shown to increase sport performance (4, 8, 12, 22).
METHODS
Experimental Approach to the Problem
A cross-sectional design aimed at providing insight into actual training practices currently implemented by competitive mountain bikers to increase riding performance was used. Due to the association between the previously mentioned performance variables within the sport of mountain biking and the training modalities associated with the physiological adaptations of these parameters, the exercise training modalities served as the driving force behind the development of the study survey. The body of scientific literature, examining the physiological training adaptations to the assessed exercise training modalities, supported each question included in the survey used in the present study. Additionally, the Delphi Method was used for the development of the survey. A focus group was used with individuals from the Birmingham Urban Mountain Pedalers (B.U.M.P.). This organization represents mountain biking for the state of Alabama and in the southeastern United States. It is part of a larger governing body known as the International Mountain Biking Association (IMBA). During the meeting, questions were presented to the group to determine the nature of training that these riders preferred. These responses were then used in the development of each survey question. Once a rough draft of the survey was constructed, it was then pre-tested among competitive mountain bikers from B.U.M.P. and then, based on feedback, was revised before being sent out for national distribution.
A nationwide online survey using the Vovici online survey system was developed based on the focus group feedback and the scientific peer-reviewed literature. A weblink to the online survey was sent via e-mail. Depending on the athlete’s responses, the survey took between 5-20 minutes to complete. The survey assessed several types of training, including high intensity interval, endurance, and resistance training. Major responses were yes and no questions that were seen by everyone that completed the survey. Depending on the answer to the major responses, the rider would move into more detailed questioning regarding the specificities of that type of training. For example, a major response question was as follows, “In an effort to improve performance, do you resistance train?” If the participant answered yes, then he/she was directed to more detailed questions regarding resistance training. If he/she answered no, the survey moved onto the next modality of training.
A Cronbach’s alpha (α) test of internal consistency among all major responses (i.e., general questions that all respondents viewed before potentially moving to more detailed questions) was conducted to determine the reliability of the present survey. The alpha value for reliability for this study was .82, suggesting a high level of internal consistency among survey items, indicating a measure of reliability for this survey (30). Response rates from a survey of this nature have been shown to vary considerably. Researchers have observed response rates from internet-based surveys ranging from 20-53% (35, 36, 42). Among respondents for the present study, 63 individuals were contacted and 40 completed the survey, providing a 64% response rate.
Subjects
Survey respondents included 27 male and 13 female competitive mountain bikers completed the online survey. The mean age of the participants was 26 ± 9 years. Riders competed in an average of 15.3 ± 9.4 races per year. The number of years spent in competitive racing averaged 4.8 ± 4.4 years. Participants were given the option of selecting all disciplines they competed in during the previous year. Ninety-three percent of riders reported competing in XC racing and 28% reported competing in DH racing. Of the 40 participants, 43% of riders competed on a sponsored local or national team, 40% of the riders competed as part of a collegiate sports club team, 28% competed on a National Collegiate Athletic Association (NCAA) team, and 23% competed as a sponsored individual. Participants for this study were a nationwide convenience sample and were recruited by contacting groups whose members are competitive mountain bikers. Sources for participant recruitment included a nationwide search on public websites and resources in the public domain. For example, university or college sponsored teams were identified from races schedules found at www.usacycling.org. This site has information on university sport’s club teams, as well as NCAA intercollegiate teams. Teams from these race schedules were identified as competitive. These teams had team page links through their university or college sports team homepages. Other competitive professional mountain bikers were identified through an internet search on a major search engine. Many of these riders have their personal webpages displaying contact information. This information was used to contact these riders as potential candidates for completing the present survey. Finally, competitive members of (B.U.M.P) were contacted as potential participants, as well as other clubs within IMBA. Riders from these clubs and teams represented all regions of the United States, including the Pacific Northwest, West Coast, East Coast, Desert Southwest, Northeast, and the Southeast. The present study was approved by the university’s Institutional Review Board, and each participant read and signed, via an electronic checkbox, a letter of consent.
Procedures
A total of 63 contacts were identified for potential participant recruitment. Sixteen coaches and 47 athletes were contacted to fill out the survey. Two versions of the recruitment letter were created; one was written for the athletes and the other for team coaches. This letter was sent via e-mail a total of 4 times during a 4-month period, and it was requested that these contacts forward the survey along to their riders and teammates. Overall, a total of 254 e-mails were sent to these 63 contacts during the 4- month period. Those who chose to complete the survey remained anonymous.
Statistical Analyses
Means and standard deviations were calculated for all continuous data, and paired t-tests were used to compare means of the normally distributed data. A Wilcoxon signed rank test was used to compare non-normally distributed data. Frequencies and proportions were calculated and used to report categorical variables. Due to its practical application for this study, the mode was also used to report the frequency of workouts sessions for both seasons. Further analyses included binomial tests, which yielded a “z” test statistic, to determine the differences in proportions. The type I error rate was set at an alpha value of .05, and standard deviations (SD) are reported with the mean values (mean ± SD). Statistical software was used for all data analyses (version 20; IBM SPSS, Chicago, IL, USA).
RESULTS
Training Information
Sources of training information for respondents were examined. Approximately fifty-eight percent of riders reported using training programs given to them by their coaches. Other sources for training information are reported in Table 1.
Resistance training during the in-season
Fifty-five percent (n = 22) of respondents reported participating in RT as a training modality during the in-season. The average number of workout sessions per week devoted to RT was 3.0 ± 1.2 days per week, with the mode calculated at 2 workout sessions per week. The average number of upper and lower body exercises selected for each workout session were 6.3 ± 2.3 and 5.9 ± 3.1 exercises, respectively. The average number of upper body and lower body workouts per week were 2.8 ±1.2 and 3.5 ± 1.8, respectively. Rider upper and lower body exercise selection, as well as the percentage of riders selecting those exercises, is illustrated in Table 2. Finally, 40.9% of the riders reported performing RT exercises using an explosive lifting tempo (i.e., greater emphasis on muscular power) whereas 59.1% reported performing RT exercises using a slow lifting tempo (i.e., greater emphasis on strength or endurance). Of the total months in-season (6.8 ± 2.9), riders spent an average of 23.1 ± 18.0 weeks implementing RT into their weekly training sessions.
Resistance training during the off-season
During the off-season, 52.5% (n = 21) of respondents reported participating in RT. Compared to the in-season, the average number of workout sessions per week devoted to RT was 2.8 ± 1.1 days per week, and the mode was 2 workout sessions per week. The average number of upper body exercises selected for each workout session was 5.4 ± 1.9, and the average number of lower body exercises selected for each session was 5.3 ± 3.2 exercises. The mean number of upper body and lower body workouts per week were 3.2 ± 2.1 and 2.9 ± 1.5 exercises, respectively. Table 3 highlights the upper and lower body exercises selected, as well as the percentage of riders selecting those exercises. Moreover, 47.6% of the riders reported performing resistance exercises using an explosive lifting tempo (i.e., greater emphasis on muscular power), whereas 52.4% reported performing RT exercises using a slow lifting tempo (i.e., greater emphasis on muscular strength or endurance). Of the total months off-season (4.6 ± 3.0), riders spent an average of 17.1 ± 11.6 weeks incorporating RT into their weekly training sessions.
Differences between the in-season and off-season
There was no difference between the proportion of riders who participated in RT during the in-season versus the off-season (z = 0.1, p = 0.5). Percentages between in-season and off-season participation in RT are presented in Figure 1. When considering comparisons between the frequency of RT workouts, analyses revealed no significant difference between the number of weekly sessions performed between the seasons (t = 0.8, df = 15, p = 0.4). Additionally, no significant difference was shown in the number of upper body (p = 0.2) and lower body (p = 0.2) workout sessions between both seasons.
DISCUSSION
The primary aim of this study was to determine the extent to which competitive mountain bikers participate in RT to increase riding performance. The secondary purpose of this study was to determine if these riders are relying on the current training recommendations associated with increased sport performance (4, 8, 12, 22). The main findings from this study indicated that approximately half of the riders incorporate RT into their workout sessions during the in- and off-seasons, and there was no significant difference between the percentage of riders that RT during the in- and off-seasons, which may suggest that riders who RT during the in-season may continue this training during the off-season. Furthermore, riders who do engage in RT are meeting a large portion of current training recommendations associated with increases in performance.
Currently, the training recommendations for frequency of RT sessions for a trained athlete is 1-3 sessions per week during the in-season and 4-6 sessions per week during the off-season (4, 9, 12, 33, 34, 43). During the in-season, riders reported an average of 3 sessions per week devoted to RT. Among riders, the most frequently reported number of workout sessions per week was two. During the off-season, the average number of sessions per week was also 3, and, like the in-season, the most frequent number of workouts per week was also two. Overall, it appears that riders are adhering to the recommended frequency of workouts sessions per week associated with increases in sport performance during the in-season. However, the number of RT sessions falls short during the off-season. The objective of the off-season should be to initially increase muscular hypertrophy and endurance, followed by a focus on strength and power development (4, 12). Riders participating in RT exercise during the off-season should consider increasing his or her workout frequency to the recommended 5-6 weekly training sessions (4, 12). Muscular and performance adaptations obtained during the off-season should translate into increased riding performance during the competition season.
Additionally, a RT program should include a variety of exercises targeted towards the upper and lower body (4, 12, 25, 40, 41). Results from the present study suggest that riders adhere to this recommendation by incorporating a variety of upper and lower body exercises into their training programs during the in-season and off-season. For both seasons, more than 70.0% of riders included RT targeting the major muscles of the upper body and over 90.0% of riders reported implementing RT focused on the major muscles of the lower body. Specifically, during the in-season, riders reported an average of 6 upper body exercises per workout sessions. Furthermore, an average of 6 lower body exercises were selected per workout sessions. When considering the off-season, an average number of 5 upper body exercises were selected per workout session, and an average number of 5 lower body exercises were selected for each workout. Not only does the percentage of participation in RT appear to remain consistent throughout the year, results suggest there is a large amount of consistency among upper and lower body training between both seasons. As mentioned earlier, the technical terrain encountered during an off-road competition incorporates elements of upper and lower body muscular strength, endurance, and power (9, 33, 34, 43). Therefore, performing RT targeting the major muscle groups of the upper and lower body should enhance performance while riding.
In terms of how the selected RT exercises were performed, results from the present study revealed that 40.9% of riders incorporated an explosive lifting tempo (i.e., greater emphasis on muscular power) during the in-season. In the off-season, 47.6% of riders reported using an explosive tempo. Power training is characterized by explosive movements focused on the maximal load that can be moved at a maximal velocity. Resistance training of this nature has been shown to increase PO by increasing a muscle’s capacity to produce reasonably large amounts of force at a high velocity (19, 20, 25, 31, 38-40). In support of an explosive lifting tempo, replacing a segment of a rider’s endurance training program with high-explosive resistance training increased PO, as well as prevented the decreases in high-intensity short-term performance associated with endurance training (2, 31). As a result, riders performing high-explosive movements may increase PO during competition, thus improving riding performance.
Conversely, 59.1% of riders reported performing resistance-training exercises at a slow-tempo during the in-season. During the off-season, 52.4% reported performing slow tempo resistance exercises. A slow lifting tempo is characterized by performing exercise movements in a slow and controlled manner. This type of lifting tempo increases the time during which force is being exerted, suggesting training oriented towards the development of strength, and, depending on the number of repetitions performed for each resistance exercise, possibly muscular endurance (4, 12). However, without determining the intensity of the workloads, it is difficult to ascertain if a slow tempo performance of exercise is focused more on the development of muscular strength or endurance. Regardless, Jackson et al. (18), found that when mountain bike riders participated in a RT program oriented towards either high volume or high intensity, significant increases in strength were experienced. It is important to note that these findings only held true when the principle of progressive overload was applied (18). RT increases strength and a muscle’s ability to generate force (4, 12, 19, 20, 25, 31, 38-40). These increases potentially contribute to a greater velocity of movement, and a greater velocity of movement may lead to greater MPO and PPO during a typical mountain bike race (6, 18, 31, 38, 44). It is possible that the riders in this study who participate in RT may have a competitive edge over those who do not. This conclusion coincides with research demonstrating PO as a performance indicator in successful mountain bike riding (1, 11, 16, 17).
Finally, during the total number of months in the in-season (6.8 ± 2.9), riders spent an average of 6 months implementing RT into their weekly workout sessions. Of the total number of months in the off-season (4.6 ± 3.0), riders spent an average of 4 months implementing RT into their weekly workout sessions. Research has shown that neurological gains associated with RT occur within the first 6-8 weeks of training, and continued gains in muscular hypertrophy, power, endurance and strength will result if training continues. The aggregate of these neurological and muscular adaptations should increase force production, and increases in force production can be translated into increases in PO (3, 7, 18, 20, 21, 24, 27). As mentioned earlier, PO has been shown to be a physiological marker associated with successful mountain bike riding. Based on results from the present study, it is evident that riders are training long enough to elicit neurological adaptation, thus increasing the probability of increasing PO while riding.
CONCLUSION
Among the riders from the present study that did RT, results suggest that these riders are meeting, for the most part, a portion of the training recommendations associated with increases in sport performance. Additionally, the total weeks spent RT during both seasons should be long enough to elicit performance adaptations. However, it is important to note that only half of the riders assessed in this study participated in some type of RT, but it appears that the consistency of this type of training remains steady throughout the entire year. Finally, due to the whole body muscular demand (e.g., power, strength, endurance) of the sport, riders that RT should have a competitive edge over riders who do not.
APPLICATIONS IN SPORT
The popularity of mountain biking has increased steadily since its inception in the 1970’s, and the number of competitive mountain bikers increases on a yearly basis. High physical conditioning is essential in performing well within the sport. As important as the training component is, very little was known regarding the extent to which competitive mountain biker’s train to enhance performance. Each discipline within the sport requires varying physical demands, and training should be specific to those demands. By having a better understanding of how and how often riders are training, program design can become more specific to meet the demands of riding. Overall, riders may want to consider implementing both power and strength training into their workout regimens, as these elements have been associated with successful riding performance.
In addition, responses from the survey used in the present study indicated that riders receive a majority of their training advice from their mountain bike coaches. Therefore, it would seem appropriate to direct mountain bike training techniques and proper program design towards the coaches, as it appears that this information would matriculate to the athletes. By having a better understanding of technique and program design, coaches can create effective training programs specifically targeted towards mountain biking performance. Furthermore, since only half of the riders assessed participated in RT, it is important to increase the awareness among these athletes regarding the performance benefits associated with RT. Additionally, if coaches are made more aware of these RT benefits as related to mountain bike riding performance, it may be possible his or her athletes would be more likely to participate in RT as part of a sports specific training regimen.
ACKNOWLEDGMENTS
None
REFERENCES
1. Baron, R. (2001). Aerobic and anaerobic power characteristics of off-road cyclists. Medicine & Science in Sports & Exercise, 33(8), 1387-1393.
2. Bastiaans, J. J., Van Diemen, A. B. J. P., Veneberg, T. V., & Jeukendrup, A. E. (2001). The effects of replacing a portion of endurance training by explosive strength training on performance in trained cyclists. European Journal of Applied Physiology, 86(1), 79-84.
3. Bishop, D., Jenkins, D. G., MacKinnon, L. T., McEniery, M., & Carey, M. F. (1999). The effects of strength training on endurance performance and muscle characteristics. Medicine & Science in Sports & Exercise, 31(6), 886-891.
4. Chandler, T. J., & Brown, L. E. (2008). Conditioning for strength and human performance: Lippincott Williams & Wilkins.
5. Costa, V., & Fernando, D. O. (2008). Physiological variables to predict performance in cross-country mountain bike races. . Journal of Applied Physiology Online, 11(6), 14-24.
6. Crieland, J. M., & Pirnay, F. (1981). Anaerobic and aerobic power of top athletes. European Journal of Applied Physiology, 47, 295-300.
7. Deschenes, M. R., & Kraemer, W. J. (2002). Performance and physiologic adaptations to resistance training. American Journal of Physical Medicine & Rehabilitation, 81(11), S3-S16.
8. Fleck, S. J., & Kraemer, W. (2014). Designing resistance training programs, 4E: Human Kinetics.
9. Fuhrmann, G. (2002). Resistance training for cyclist. National Strength and Conditioning Association’s Performance Training Journal, 1(5), 15-23.
10. Garhammer, J. (1993). A review of power output studies of olympic and powerlifting: methodology, performance, prediction, and evaluation tests. Journal of Strength and Conditioning Research, 7(2), 76-89.
11. Gregory, J., Johns, D. P., & Walls, J. T. (2007). Relative vs. absolute physiological measures as predictors of mountain bike cross-county race performance. Journal of Strength and Conditioning Research, 21(1), 17-22.
12. Haff, G. G., & Triplett, N. T. (2015). Essentials of Strength Training and Conditioning 4th Edition: Human kinetics.
13. Hickson, R. C., Dvorak, B. A., Gorostiaga, E. M., Kurowski, T. T., & Foster, C. (1988). Potential for strength and endurance training to amplify endurance performance. Journal of Applied Physiology, 65(5), 2285-2290.
14. Hurst, H. T., & Atkins, S. (2006). Power output of field-based downhill mountain biking. Journal of Sports Sciences, 24(10), 1047-1053.
15. Hurst, H. T., Swarén, M., Hébert-Losier, K., Ericsson, F., Sinclair, J., Atkins, S., & Holmberg, H.-C. (2012). Influence of course type on upper body muscle activity in elite cross-country and downhill mountain bikers during off road downhill cycling. Journal of Science and Cycling, 1(2), 2.
16. Impellizzeri, F. M., Marcora, S. M., Rampinini, E., Mognoni, P., & Sassi, A. (2005). Correlations between physiological variables and performance in high level cross-country off road cyclists. British Journal of Sports Medicine, 39, 747-751.
17. Impellizzeri, F. M., Rampinini, E., Sassi, A., Mognoni, P., & Marcora, S. (2005). Physiological correlates to off-road cycling performance. Journal of Sports Sciences, 23(1), 41-47.
18. Jackson, N. P., Hickey, M. S., & Reiser II, R. F. (2007). High resistance/low repetition vs. low resistance/high repetition training: effects on performance of trained cyclists. Journal of Strength and Conditioning Research, 21(1), 289-295.
19. Jenson, C. R., & Fisher, A. G. (1979). Scientific basis of athletic conditioning. Philadelphia, PA: Lea & Febiger.
20. Kawamori, N., & Haff, G. G. (2004). The optimal training load for the development of muscular power. The Journal of Strength & Conditioning Research, 18(3), 675-684.
21. Knuttgen, H. G., & Kraemer, W. J. (1987). Terminology and measurement in exercise performance. Journal of Strength and Conditioning Research, 1(1), 1-10.
22. Kraemar R, W. J., & Ratamess, N. A. (2004). Fundamentals of resistance training: Progression and exercise prescription. Medicine & Science in Sports & Exercise, 36(4), 674-688.
23. Kraemer, W., & Koziris, L. (1992). Muscle strength training: Techniques and considerations. Phys.Ther. Pract, 2, 54-68.
24. Kraemer, W. J., Deschenes, M. R., & Fleck, S. J. (1988). Physiological adaptations to resistance exercise implications for athletic conditioning. Sports Medicine, 6(4), 246-256.
25. Kraemer, W. J., Ratamess, N. A., & French, D. N. (2002). Resistance training for health and performance. Current Sports Medicine Reports, 1(3), 165-171.
26. Lee, H., Martin, D. T., Anson, J. M., Grundy, D., & Hahn, A. G. (2002). Physiological characteristics of successful mountain bikers and professional road cyclists. Journal of Sports Sciences, 20(12), 1001-1008.
27. Levin, G. T., McGuigan, M. R., & Laurson, P. B. (2009). Effect of concurrent resistance and endurance training on physiologic and performance parameters of well-trained endurance cyclists. Journal of Strength and Conditioning Research, 23(8), 2280-2286.
28. Marcinik, E. J., Potts, J., Schabach, Will, S., Dawson, P., & Hurley, B. F. (1991). Effects of strength training on lactate threshold and endurance performance. . Medicine & Science in Sports & Exercise,, 23(6), 739-743.
29. Newton, R. U., Kraemer, W. J., Häkkinen, K., Humphries, B. J., & Murphy, A. J. (1996). Kinematics, kinetics, and muscle activation during explosive upper body movements. Journal of Applied Biomechanics, 12(1), 31-43.
30. Nunnally, J. (1978). C.(1978). Psychometric theory, 2.
31. Paton, C. D., & Hopkins, W. G. (2005). Combining explosive and high-resistance training improves performance in competitive cyclists. Journal of Strength and Conditioning Research,, 19(4), 826-830.
32. Prins, L., Terblance, W., & Myburgh, K. H. (2007). Field and laboratory correlates of performance in competitive cross-country mountain bikers. Journal of Sports Sciences, 25(8), 927-935.
33. Rhyan, S. (1998). Strength and conditioning considerations for mountain bike racing. Strength and Conditioning Journal, 20(5), 36-39.
34. Rhyan, S. (2005). Training suggestions for the downhill mountain bike racer. Strength and Conditioning Journal, 27(5), 42-45.
35. Sax, L. J., Gilmartin, S. K., & Bryant, A. N. (2003). Assessing response rates and nonresponse bias in web and paper surveys. Research in Higher Education, 44(4), 409-432.
36. Sheehan, K. B. (2001). E‐mail survey response rates: A review. Journal of Computer‐Mediated Communication, 6(2), 0-0.
37. Stapelfeldt, B., Schwirtz, A., Schumacher, Y. O., & Hillebrecht, M. (2004). Workload demands in mountain bike racing. International Journal of Sports Medicine, 25(4), 294-300.
38. Stone, M. H., Byrd, R., Tew, J., & Wood, M. (1980). Relationship between anaerobic power and olympic weightlifting performance. Journal of Sports Medicine and Physical Fitness, 20(1), 88-102.
39. Stone, M. H., Fleck, S. J., Triplett, N. T., & Kraemer, W. J. (1991). Health and performance related potential of resistance training. Sports Medicine, 11(4), 210-231.
40. Stone, M. H., & O’Bryant, H. (1987). Weight training: A scientific approach. Minneapolis, MN: Burgess International.
41. Tesch, P. (1992). Training for bodybuilding. Strength and Power in Sport, 3, 370-379.
42. Truell, A. D., Bartlett, J. E., & Alexander, M. W. (2002). Response rate, speed, and completeness: A comparison of Internet-based and mail surveys. Behavior Research Methods, Instruments, & Computers, 34(1), 46-49.
43. Willis, C. M., & Jones, M. T. (1999). Implementing resistance training into the macrocycles of a competitive mountain biker. Strength and Conditioning Journal, 21(6), 33-39.
44. Wilmore, J. H., Costill, D. L., & Kenney, W. L. (2008). Physiology of Sport and Exercise (4th ed.). Champaign, IL: Human Kinetics.
45. Wilson, G. J., Elliott, B. C., & Kerr, G. K. (1989). Bar path and force profile characteristics for maximal and submaximal loads in the bench press. International Journal of Sport Biomechanics, 5(4), 390-402.
