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HEDELIN, R., G. KENTTÄ, U. WIKLUND, P. BJERLE, and K. HENRIKSSON-LARSÉN. Short-term overtraining: effects on performance, circulatory responses, and heart rate variability. Med. Sci. Sports Exerc. Vol. 32, No. 8, pp. 1480–1484, 2000.Nine elite canoeists were investigated concerning changes in performance, heart rate variability (HRV), and blood-chemical parameters over a 6-d training camp. The training regimen consisted of cross-country skiing and strength training, in total 13.0 ± 1.6 h, corresponding to a 50% increase in training load.Time to exhaustion (RunT) decreased from 19.1 ± 1.0 to 18.0 ± 1.2 min (P < 0.05). V̇O2max and max lactate (Lamax) both decreased significantly (P < 0.05) over the training period (4.99 ± 0.97 to 4.74 ± 0.98 L·min−1 and from 10.08 ± 1.25 to 8.98 ± 1.03 mmol·L−1 respectively). Heart rates (HR) decreased significantly at all workloads. Plasma volume increased by 7 ± 7% (P < 0.05). Resting cortisol, decreased from 677 ± 244 to 492 ± 222 nmol·L−1 (P < 0.05), whereas resting levels of adrenaline and noradrenaline remained unchanged. The change between tests in RunT correlated significantly with the change in HRmax (r = 0.79;P = 0.01). There were no group changes in high or low frequency HRV, neither at rest nor following a tilt.The reduced maximal performance indicates a state of fatigue/overreaching and peripheral factors are suggested to limit performance even though HRmax and Lamax both were reduced. The reduced submaximal heart rates are probably a result of increased plasma volume. HRV in this group didn’t seem to be affected by short-term overtraining.