The aims of this study were to assess changes in heart rate variability (HRV) during a 3-week intensive training period, followed by 3 weeks of taper and one week of competition, and correlate changes in HRV with changes in performance (LlP). In thirteen elite swimmers (6 female, 7 male Their mean age, body weight and height at inclusion in the study was 18,3 ± 1,2 years, 55± 3 kg, and 167 ± 5 cm for females and 19,2 ± 1,7 years, 74 ± 2 kg and 181 ± 5 cm for males. All subjects had a history of more than 5 years of practice at national and international level. Diurnal standard indices of HRV were assessed by time domain and spectral analysis at the end of each period in supine (SU), supine control breathing (CB) and standing position (ST), and compared to a control age-and sex-matched sedentary group. The weekly training volume performed in dry-land workout (DL) and for swimming, under and above the individual anaerobic threshold (respectively Ll and HI) was recorded. During the taper the swimming training load decreased substantially as well as the parasympathetic indices in standing position SD1ST (28.7 ± 18.8 vs. 18.8 ± 14.3 ms); RMSSDST (40.6 ± 41.3 vs. 26.5 ± 20.2 ms); HFST, (1141.9 ± 2733.6 vs. 400.7 ± 608.8 ms^2) (P<0.05). Conversely, during the competition period, several HRV indices increased pNN50SU, (0.19 ± 0.08 vs. 0.22 ± 0.09%); RMSSDSU, (68.4 ± 32.7 vs. 82.2 ± 35.9 ms); LFSU, (2301.7 ± 1699.5 vs. 2491 ± 1690 ms^2); SD1CB, (55.7 ± 22.7 vs. 70.1 ± 38.1 ms); RMSSDCB, (78.4 ± 31.9 vs. 98.3 ± 53.3 ms); HFCB, (3694.2 ± 2482.5 vs. 5342.9 ± 4403.4 ms^2); (P<0.05). Improvement in LlP was positively correlated with an increase in HFcs and a decrease in LFcs expressed in normalised units (r2 =0.64, r 2 =-0.64, P<O.OS). The decrease in low intensity training during the competition was correlated to the increase in LF/HFCB (r 2 = 0.64, P<0.05). Heart rate variability decreased during taper and increased during competition. During the competition week, low intensity training was associated with a higher maintenance of parasympathetic modulation.
© Copyright 2014 XIIth International Symposium for Biomechanics and Medicine in Swimming. Published by Australian Institute of Sport. All rights reserved.