Leistungsniveau, Herzfrequenz-Regulation und psychologische Faktoren als potentielle Prädiktoren von « Übertraining » im Ausdauer-sport: Ergebnisse einer Prospektivstudie mit Spitzenathleten

The main objective of this non-experimental prospective study was to evaluate the joint use of mood scores, an orthostatic heart rate test, and the description of training characteristics for an early detection of overreaching (OR) in elite endurance athletes. We followed up 11 high performance, non-professional endurance athletes (23.6 ± 4.4 a) - orienteers (5 ♂, 2 ♀), triathletes (3 ♂) and a duathlete (♀)- during 35.9 ± 5.4 weeks without interfering with their training schedule. A broad assessment was used, including training volume, the relation of planned to completed training (ATr), resting heart rate (RHR), difference between resting heart rate supine and standing (orthostatic test; AHR), the Profile of Mood States (POMS) and the Recovery-Stress-Questionnaire for Athletes (RESTQ-Sport). Main outcome measures were: a) incidence of OR and OTS and b) incidence of an unplanned reduction in training volume of at least 20% (ΔTr ≤ 0.8). Treadmill tests were performed at least bimonthly, two to six times per athlete for performance assessment and diagnosis of OR. During 395 person-weeks of follow-up, we found no athlete with symptoms and signs of OTS. One athlete suffered from one episode of OR, documented by impaired results in the performance test. In this case, training volume before OR was average, but out of training time was full of duties. RHR was within the personal range. A rise in ΔHR of about eight bpm (from 23 to 31) three weeks before OR was followed by a steep drop of about 17 bpm (from 31 to 14 bpm) the following two weeks. Values of AHR returned to normal variation three weeks thereafter. EBF and POMS-scores showed no consistent pattern before the episode of OR. Ten athletes progressed to 49 unplanned reductions of their training volume for 20% or more (between 1 and 10 times per athlete), mainly because of infectious diseases (43%), injuries (20%), and fatigue (18%). On average, three more weeks of reduced training followed the reduction because of fatigue. In search of predictors of fatigue, neither EBF nor POMS were generally predictive, but both scores increased in the following weeks with reduced training. RHR and ΔHR showed no consistent correlation with fatigue induced training reduction. Using an individual approach, it was nevertheless possible to identify «individually correct» associations between one or more specific predictors and a defined outcome. In summary, in the one case of OR, our predictors were related to the condition, but did not precede it in an unequivocal way. The parameters under study were rather general signs of an unbalanced state of stress and recovery than real warning sings of the outcomes. Our results suggest that even by a combination of presumed «predictors of overtraining» it is not possible to detect impending overreaching in a general way. However, using a strictly individualized approach, every single parameter under study might be a predictor of fatigue, when compared to an individual reference value, a so-called «personal baseline». The most promising road to monitor the training regimen of a given athlete, and to detect early signs of OR, might be an even more systematic search for individual patterns of behaviour and variations regarding the presumed predictive parameters of OR and OTS.