Kinetics of submaximal DFA α1 prior and post maximal efforts in trained and highly trained male and female cyclists.

PURPOSE: To investigate the kinetics of a non-linear heart rate (HR) variability parameter (DFA α1) during submaximal cycling in male and female trained and highly trained cyclists in a non-fatigued state and after repeated maximal cycling bouts.

METHODS

N = 47 participants (17 female) completed a cycling protocol consisting of two blocks (Block1, Block2), each including two standardised submaximal cycling bouts performed prior (PRE) and post a maximal incremental test (POST), having four time points (Block1: PRE1-POST1; Block2: PRE2-POST2). DFA α1, oxygen consumption ([Formula: see text]), HR, respiratory frequency (RF) and rating of perceived exertion (RPE) were assessed during the submaximal bouts, and [Formula: see text] peak and maximal power output (Wmax) during the maximal tests. A linear mixed effects model was used to analyse data.

RESULTS

Block2 showed significantly lower [Formula: see text] peak (β =  - 2.51 mL·kg⁻¹·min⁻¹) and Wmax (β =  - 24.3 W) values. DFA α1 decreased significantly from PRE1 (1.32 ± 0.19) to POST1 (1.12 ± 0.34) and remained suppressed at Block2 (1.14 ± 0.31, 1.09 ± 0.35). [Formula: see text] (+ 2.37 mL·kg⁻1·min⁻1), HR (+ 15 bpm), RF (+ 8 breaths/min) and RPE (+ 2) increased significantly in Block1 and stayed elevated in Block2. Following POST2, HR decreased (-4 bpm) and RF increased (+ 1 breaths/min) significantly. Training status significantly influenced absolute levels of DFA α1, HR, and [Formula: see text], but did not influence RPE or RF. Sex did not significantly alter kinetics of DFA α1, HR, V̇O₂, RPE and RF.

CONCLUSION

DFA α1 during submaximal exercise reflects both acute fatigue and non-recovered state in a repeated maximal test setting and may provide complementary information on autonomic and systemic demands when interpreted alongside [Formula: see text], HR, RF and RPE.