Abstract
We aimed to analyse the relationship between training load/intensity and different
heart rate variability (HRV) fatigue patterns in 57 elite Nordic-skiers. 1063 HRV
tests were performed during 5 years. R-R intervals were recorded in resting supine
(SU) and standing (ST) positions. Heart rate, low (LF), high (HF) frequency powers
of HRV were determined. Training volume, training load (TL, a.u.) according to ventilatory
threshold 1 (VT1) and VT2 were measured in zones I≤VT1; VT1<II≤VT2; III>VT2, IV for
strength. TL was performed at 81.6±3.5% in zone I, 0.9±0.9% in zone II, 5.0±3.6% in
zone III, 11.6±6.3% in zone IV. 172 HRV tests matched a fatigue state and four HRV
fatigue patterns (F) were statistically characterized as F(HF-LF-)SU_ST for 121 tests,
F(LF+SULF-ST) for 18 tests, F(HF-SUHF+ST) for 26 tests and F(HF+SU) for 7 tests. The
occurrence of fatigue states increased substantially with the part of altitude training
time (r2=0.52, p<0.001). This study evidenced that there is no causal relationship
between training load/intensity and HRV fatigue patterns. Four fatigue-shifted HRV
patterns were sorted. Altitude training periods appeared critical as they are likely
to increase the overreaching risks.
Key word
heart rate variability - fatigue - training load - endurance training - altitude training