Sammendrag
Abstract
Introduction: Competitive endurance athletes regularly go through planned phases of increased training load (training-overload) and tapering (reduction in training load) as part of their training regimes to enhance performance. Nonetheless, increases in training load are not always met by a compensatory increase in energy intake, leading to low energy availability (LEA) and possibly a diagnosis of relative energy deficiency in sport (REDs). Most previous studies in the field have focused on measures of LEA and related biomarkers alone, and only few studies have investigated training-overload and performance together with different contemporary REDs indicators based on the newest IOC consensus statement. Therefore, the overall aim of this study was to investigate the influence of a 2-week training-overload period on performance and REDs indicators in endurance athletes. Methods: A total of 11 trained endurance athletes (M=7, F=4, VO2max = 61.3±7.1 ml/kg(min) participated in this study. The participants completed 1-week baseline-training period, a 2-week training-overload period (50-70% progressive increase in training load), and a 1-week recovery period (30-40% reduction in training load from baseline). Immediately after each training period, physiological responses during a maximal incremental time to exhaustion (TTE) test while treadmill-running together with various REDs indicators including eating disorder questionnaire (EDE-Q), libido questionnaire (LEAMQ), and blood biomarkers (Testosterone, cortisol, total and LDL-cholesterol, triiodothyronine, growth hormone, prolactin). Training data as well as readiness measures were monitored daily. Results: Performance measured as TTE were not reduced from baseline to training-overload period but increased from the baseline to recovery period (∆25.5±7.2 sec, p <.05, respectively). Physical and mental readiness measures were reduced after the training-overload period (∆1.1±0.6 points and ∆1.4±0.6, p <.05, respectively) but returned to baseline levels after the recovery period. No significant changes in any REDs indicators were found between the baseline, training-overload and recovery period. Conclusion: A 2-week training-overload period in endurance athletes have no negative influence on either performance or REDs indicators. Although subjective fatigue markers were influenced by increased training load this implies that the protocol in the current study were well-tolerated probably due to a compensatory increase in energy intake. This pilot study can be used as a starting point to further investigate the influence of training-overload on performance and REDs indicators in endurance athletes by including larger samples and possible also sex-differences and female-specific considerations.
Key words: Endurance athletes, training-overload, REDs, biomarkers