No significant main effects or interactions were identified for the Sal-C, and 1RM data across either the simulated or actual competitions (p > 0.05). Thus, data from each competition setting were pooled for analysis. Pre and post Sal-C values were higher during the actual (vs. simulated) competitions (p < 0.001, Figure 2), but no significant changes (from pre to post) in Sal-C occurred across either condition (p > 0.05).
The pooled 1RM and rel1RM values for the clean and jerk, and the Olympic total lift, were both found to be greater in the actual (vs. simulated) competitions (p < 0.05, Table 3). The snatch 1RM and rel1RM lifts were not significantly different (p > 0.05).
Significant correlations were found between individual Sal-C concentrations before the simulated competitions and the snatch, clean and jerk, and Olympic total 1RM lifts (r = 0.48-0.49, p < 0.05). No significant correlations were identified between these parameters during the actual competitions (r = 0.09-0.012, p > 0.05) or between Sal-C and the rel1RM lifts in either competition (r = 0.16-0.27, p > 0.05).
This study on Olympic weightlifters revealed 3 main findings: First, the weekly changes in training volume had no apparent effect on Sal-C concentrations; second, actual competitions produced higher Sal-C concentrations and superior 1RM lifts (clean and jerk, Olympic total) than the simulated competitions; third, individual Sal-C concentrations before the simulated competitions correlated to all of the 1RM lifts.
Adjustments in training volume have been shown to alter C concentrations in male and female weightlifters (13,14,18,20,21,23). In general, the greater the training stress (i.e., higher training volume and intensity) imposed on the neuromuscular system, the greater the C changes occurring. The lack of any significant Sal-C responses over the 5 weeks of this study could be explained by the absolute volume of training, the time of exposure to different training volumes, and the competition phase, relative to previous research. Baseline C concentrations at the start of this study could also be important in this regard. Previous studies also suggest that C modifications may affect the T/C ratio and thus one's ability to express strength and recovery from training and competitions (13,18,22,23). This is difficult to confirm with only C monitored in this study and given the low statistical power of the training results.
The actual weightlifting competitions produced higher (128-130%) Sal-C concentrations than the simulated ones, which could be explained by the greater challenge, motivation, and stress presented by a real event (32,35). Highly trained athletes might also possess an adrenal system that responds more to competition (i.e., greater C response) than lesser trained individuals (32,37). Other competition factors influencing hormone secretion include physical fitness, physical effort or exertion, mood, motivation, coping styles, and player position (35). We recognize that the Sal-C results in this study might be affected by circadian variation (26), because the actual events began earlier in the day than the simulated ones. However, the differences in Sal-C concentrations between the respective competitions were still much greater than time-matched control data (26,39). Nutritional intake is another confounding variable when assessing Sal-C levels (15).
The 1RM lifts in the actual competitions were generally superior (1.9-2.6%) to that seen in the simulated events and this may be explained. Similarly, improvements in the 1RM performance of Olympic weightlifters were noted during actual (vs. simulated) competition when Sal-C also increased by more than twofold (32). A rise in C levels has been observed in many sporting competitions (11,12,25,31,36-38), and these hormonal changes often enhanced the performance and behavioral outcomes. For example, judoists displaying higher Sal-C levels also had higher motivation to perform and obtained the better outcome (36), and higher C levels were found in judo winners when compared with losers (38). and. These data confirm suggestions that C may be essential for working capacity and performance (40). Thus, acute elevations in C may actually benefit athlete performance during competition.
Positive correlations were demonstrated between individual Sal-C concentrations, and the 1RM lifts during the simulated competitions, similar to previous work (5,6,32) This work implies that higher Sal-C concentrations (on an individual level) may also benefit 1RM performance during weight training procedures. No significant relationships were observed during the actual competitions, which could be explained by individual variation in the adrenal responses to the competitive environment, especially since participant C levels were already elevated. Nevertheless, the correlations in this study only approached moderate strength and notwithstanding the fact that they still only reflect casual relationships between variables. Other research on weightlifters have also reported no discernable relationships between these variables (4,13), possibly resulting from differences in training procedures and study design.
The mechanism(s) by which elevated C levels may improve athlete performance is multifactorial. Cortisol may contribute to human and muscle performance by regulating or controlling energy metabolism (40), motor cortex function (34), the electrophysiological properties of muscle (7), and intracellular signals (30). Additionally, C can affect brain neural activity (29) and cognitive function (24,33), and this has further implications for the expression of human movement in sport. Further research is needed to elucidate those C-related mechanisms contributing to athletic performance. This information would help in the management, assessment, and training of athletes within their sporting environment.
Other limitations of this study include the lack of a nontraining control group and the small number of subjects recruited, although the pool of Olympic weightlifters available for research is limited. Indeed, the size of our study population is consistent with that of other studies in this area (1,4,14,17-19,21). We also acknowledge the possible confounding effects of treatment order, or any interactions thereof, given the current study design (i.e., simulated competitions before the actual competitions) and the differences in training volume before the respective competitions (i.e,. high- and low-volume weeks). However, these are inherent problems when working with elite athletic groups so the observed findings do reflect the actual sporting environment. Finally, we acknowledge that other hormones (e.g., T, growth hormone, insulin-like growth factor 1, catecholamines) may help to regulate athlete performance, but their discussion is beyond the scope of this article.
In conclusion, actual competitions produced greater Sal-C responses than simulated competitions, and this appeared to benefit the 1RM performance of Olympic weightlifters. Individuals with higher Sal-C concentrations also tended to exhibit superior 1RM lifts during the simulated competitions.
The results of this study suggest that higher C concentrations may benefit weightlifting performance. Consequently, greater emphasis should be placed upon the monitoring of C to establish normative values and training standards for individual weightlifters or weight-trained athletes, and to assist with performance prediction in this sport. Researchers and practitioners could potentially use different strategies (e.g., nutrition, physical and psychological activities), or address the timing of exercise (i.e., diurnal variation), to modify C concentrations during training and competition, thereby reducing the potential for overreaching and overtraining while augmenting weightlifting performance.
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