To investigate whether monitoring of easily measurable stressors and symptoms can be used to distinguish early between acute fatigue (AF) and functional overreaching (FOR).


The study included 30 subjects (11 female, 19 male; age 40.8 ± 10.8 y, VO2max 51.8 ± 6.3 mL · kg–1 · min–1) who participated in an 8-d cycling event over 1300 km with 18,500 climbing meters. Performance was measured before and after the event using a maximal incremental test. Subjects with decreased performance after the event were classified as FOR, others as AF. Mental and physical well-being, internal training load, resting heart rate, temperature, and mood were measured daily during the event. Differences between AF and FOR were analyzed using mixed-model ANOVAs. Logistic regression was used to determine the best predictors of FOR after 3 and 6 d of cycling.


Fifteen subjects were classified as FOR and 14 as AF (1 excluded). Although total group changes were observed during the event, no differences between AF and FOR were found for individual monitoring parameters. The combination of questionnaire-based changes in fatigue and readiness to train after 3 d cycling correctly predicted 78% of the subjects as AF or FOR (sensitivity = 79%, specificity = 77%).


Monitoring changes in fatigue and readiness to train, using simple visual analog scales, can be used to identify subjects likely to become FOR after only 3 d of cycling. Hence, we encourage athlete support staff to monitor not only fatigue but also the subjective integrated mental and physical readiness to perform.

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ten Haaf, Oudenhoven, Daanen, and de Koning are with the Dept of Human Movement Sciences, MOVE Research Inst Amsterdam, Amsterdam, the Netherlands. van Staveren and Koenderman are with the Dept of Respiratory Medicine, University Medical Center Utrecht, Utrecht, the Netherlands. Piacentini is with the University of Rome “Foro Italico,” Rome, Italy. Meeusen and Roelands are with the Human Physiology Research Group. Vrije Universiteit Brussel, Brussels, Belgium. Foster is with the Dept of Exercise and Sports Science, University of Wisconsin–La Crosse, La Crosse, WI.

Address author correspondence to Twan ten Haaf at tpg.ten.haaf@vu.nl.