Nonfunctional overreaching during off-season training for skill position players in collegiate American football
Human Performance Laboratories, Department of Health and Sport Sciences, The University of Memphis, Memphis, Tennessee 38152, USA. The Journal of Strength and Conditioning Research
(Impact Factor: 2.08).
08/2007; 21(3):793-800. DOI: 10.1519/R-20906.1
The purpose of this study was to determine the performance and hormonal responses to a 15-week off-season training program for American football. Nine skill position players from a National Collegiate Athletic Association (NCAA) Division I-A football team participated as subjects in this study. Following 4 weeks of weight training (phase I), subjects performed weight training concurrently with high-volume conditioning drills (phase II). Phase III consisted of 15 spring football practice sessions executed over a 30-day period. Performance and hormonal changes were assessed prior to phase I, and following phases I, II, and III. Maximal strength was significantly increased (p < 0.05) for all strength tests during phase I. Squat and power clean values decreased following phase II (p < 0.05), with all values returning to baseline upon completion of phase III. Sprinting speed significantly worsened during phase I (p < 0.05), but then returned to baseline during phase III. Vertical jump and agility improved during phase I (p < 0.05), with vertical jump remaining unchanged for the duration of the study and agility returning to baseline following phase II. Testosterone levels decreased during phase II (p < 0.05) prior to returning to baseline levels during phase III. Cortisol and the testosterone/cortisol ratio remained unchanged during the course of the investigation. Even though overtraining did not occur in the current investigation, a significant maladaptation in performance did occur subsequent to phase II. For this particular athletic population, a strength and conditioning program utilizing a reduced training volume-load may prove more effective for improving performance in the future.
Available from: ecu.edu.au
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ABSTRACT: The first purpose of this research was to establish the reliability of numerous measures obtained from a single and short duration repeated countermovement jump (CMJ) utilising a portable forceplate (Experimental Studies 1 and 2). Secondly, the response of reliable CMJ variables and T, C and T:C to a single elite level ARF match was assessed to identify the pattern of response and highlight those measures with the greatest potential for usefulness as monitoring tools across longer periods (Experimental Study 3). Finally, those variables identified as most valuable in Experimental Study 3 in addition to T, C and T:C; were measured throughout a season of elite ARF competition in order to examine the manner of their response and assess the magnitude of change in these variables in relation to performance and training and competition loads (Experimental Study 4).
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ABSTRACT: For elite athletes, testosterone and cortisol play an important role in the training process by controlling long-term muscle growth and performance. Studies now support the existence of short-term hormonal effects upon athletic performance and training adaptation, especially for strength-trained athletes. Elite rugby players represent one group of strength athletes for which there is little hormonal information. The major aims of the work in this thesis were to measure, confirm and utilize the short-term effects of testosterone and cortisol to improve performance and adaptation in elite male rugby players.Experiment one validated the salivary testosterone (Sal-T) and cortisol (Sal-C) concentration (v. plasma) measures during dynamic changes induced by a 30-second cycle sprint, and confirmed the ability of sprint exercise to elevate the salivary hormones. Experiment two was undertaken to confirm hormonal relationships with running speed, squat jump (SJ) and bench throw (BT) power, and box squat (BS) and bench press (BP) one repetition maximum (1RM) strength in rugby players. The salivary hormone concentrations of players correlated to various speed, power and strength measures. This study also revealed performance similarities and differences between larger rugby forwards and smaller backs. Allometric scaling was found effective in normalizing power and strength in rugby forwards and backs in Experiment three.Experiments four and five evaluated the effects of sprint exercise (as a potentiating stimulus) upon the salivary hormones and workout performance and training adaptation in rugby players. A 40-second cycle sprint improved BS 1RM (2.6 ± 1.2%) and elevated Sal-T concentrations. A 40-second grinder sprint also improved BP 1RM (2.8 ± 1.0%) with the workout differences (%) in hormone concentrations correlating to BP performance. Thus, the salivary hormonal changes that occurred offered one possible mechanism to explain these improvements. These results were not replicated in a four-week training study. The training group performing a 40-second cycle sprint showed similar improvements in SJ power (peak 8.2 ± 2.9%, mean 11.8 ± 2.6%) and BS 1RM (20.5 ± 2.6%), compared to a control group (11.9 ± 3.6%, 18.6 ± 4.8%, 23.2 ± 1.3%, respectively). Still, for all players combined, resting salivary hormone concentrations were correlated to workout power and strength, thereby potentially moderating the training improvements. This work provides new evidence for the short-term effects of testosterone and cortisol upon athletic performance and training adaptation in elite male rugby players. This is novel information with important implications for examining, interpreting and utilizing hormones in sport science research and practice.
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