Research article - (2023)22, 806 - 815
DOI: https://doi.org/10.52082/jssm.2023.806
Acute Effects of Fatigue on Cardiac Autonomic Nervous Activity
Yan Chen1,2,† , Meng Liu3,† , Jun Zhou4, Dapeng Bao5,, Bin Li6, Junhong Zhou7
1Sports Department, Beihang University, Beijing, China
2Intelligent Sports Joint Research Center, Beihang University, Beijing, China
3Sports Coaching College; Beijing Sport University, Beijing, China
4China Athletics College, Beijing Sport University, Beijing, China
5China Institute of Sport and Health Science, Beijing Sport University, Beijing, China
6Cycling and Fencing Administrative Center, General Administration of Sport of China, Beijing, China
7Hebrew SeniorLife Hinda and Arthur Marcus Institute for Aging Research, Harvard Medical School, Boston, MA, United States
† The two authors contributed equally to this work

Dapeng Bao
✉ China Institute of Sport and Health Science, Beijing Sport University, Beijing, China
Email: baodp@bsu.edu.cn
Received: 20-08-2023 -- Accepted: 23-11-2023
Published (online): 01-12-2023
ABSTRACT

The onset of fatigue disrupts the functioning of the autonomic nervous system (ANS), potentially elevating the risk of life-threatening incidents and impairing daily performance. Previous studies mainly focused on physical fatigue (PF) and mental fatigue (MF) effects on the ANS, with limited knowledge concerning the influence of physical-mental fatigue (PMF) on ANS functionality. This study aimed to assess the immediate impact of PMF on ANS function and to compare its effects with those of PF and MF on ANS function. Thirty-six physically active college students (17 females) without burnout performed 60-min cycling exercises, AX-Continuous Performance Task (AX-CPT), and cycling combined with AX-CPT to induce PF, MF, and PMF respectively. Subjective fatigue levels were measured using the Rating of Perceived Exertion scale and the Visual Analog Scale-Fatigue. Heart rate variability was measured before and after each protocol to assess cardiac autonomic function. The proposed tasks successfully induced PF, MF, and PMF, demonstrated by significant changes in subjective fatigue levels. Compared with baseline, PMF decreased the root mean square of successive differences (RMSSD) between normal heartbeats (P < 0.001, d = 0.50), the standard deviation of normal-to-normal RR intervals (SDNN) (P < 0.01, d = 0.33), and the normalized high-frequency (nHF) power (P < 0.001, d = 0.32) while increased the normalized low-frequency (nLF) power (P < 0.001, d = 0.35) and the nLF/nHF ratio (P < 0.001, d = 0.40). Compared with MF, PMF significantly decreased RMSSD (P < 0.001, η2 = 0.431), SDNN (P < 0.001, η2 = 0.327), nLF (P < 0.01, η2 = 0.201), and nHF (P < 0.001, η2 = 0.377) but not the nLF/nHF ratio. There were no significant differences in ∆HRV (i.e., ∆RMSSD, ∆SDNN, ∆nLF/nHF, ∆nLF, and ∆nHF), heart rate, and training impulse between PF- and PMF-inducing protocols. Cognitive performance (i.e., accuracy) in AX-CPT during the PMF-inducing protocol was significantly lower than that during the MF-inducing protocol (P < 0.001, η2 = 0.101). PF and PMF increased sympathetic activity and decreased parasympathetic activity, while MF enhanced parasympathetic activity.
Key words: Physical fatigue, mental fatigue, physical-mental fatigue, heart rate variability, cardiac autonomic activity

Key Points
  • The study examines how combined physical and mental fatigue (PMF) affects the autonomic nervous system, contrasting its impact with physical (PF) or mental fatigue (MF) alone.
  • PMF significantly reduced parasympathetic and increased sympathetic nervous system markers.
  • PMF had a greater impact on autonomic function than MF alone, similar to PF.
  • Cognitive abilities were more adversely affected by PMF than by MF alone.








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Acute Effects of Fatigue on Cardiac Autonomic Nervous Activity
Yan Chen, Meng Liu, Jun Zhou, Dapeng Bao, Bin Li, Junhong Zhou
2023(22), 806 - 815.
DOI: https://doi.org/10.52082/jssm.2023.806