Mechanism of Fatigue Induced by Different Cycling Paradigms With Equivalent Dosage

Miao-Ju Hsu; Hsiao-Lung Chan; Ying-Zu Huang; Jau-Hong Lin; Heng-Hsiang Hsu; Ya-Ju Chang

doi:10.3389/fphys.2020.00545

Mechanism of Fatigue Induced by Different Cycling Paradigms With Equivalent Dosage

Front Physiol. 2020 May 29:11:545. doi: 10.3389/fphys.2020.00545. eCollection 2020.

Authors

Miao-Ju Hsu^{1

2}, Hsiao-Lung Chan^{3

4}, Ying-Zu Huang^{4

5

6}, Jau-Hong Lin^{1

2}, Heng-Hsiang Hsu⁷, Ya-Ju Chang^{4

7}

Affiliations

¹ Department of Physical Therapy, College of Health Science, Kaohsiung Medical University, Kaohsiung, Taiwan.
² Department of Physical Medicine and Rehabilitation and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
³ Department of Electrical Engineering, College of Engineering, Chang Gung University, Taoyuan, Taiwan.
⁴ Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
⁵ Department of Neurology, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
⁶ School of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
⁷ School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, and Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan.

Abstract

Leg cycling is one of the most common modes of exercise used in athletics and rehabilitation. This study used a novel cycling setting to elucidate the mechanisms, central vs. peripheral fatigue induced by different resistance with equivalent works (watt^∗min). Twelve male adults received low and relatively high resistance cycling fatigue tests until exhausted (RPE > 18) in 2 weeks. The maximal voluntary contraction, voluntary activation level, and twitch forces were measured immediately before and after cycling to calculate General (GFI), central (CFI), and peripheral (PFI) fatigue indices of knee extensors, respectively. The results showed that the CFI (high: 92.26 ± 8.67%, low: 78.32 ± 11.77%, p = 0.004) and PFI (high: 73.76 ± 17.32%, low: 89.63 ± 11.01%, p < 0.017) were specific to the resistance of fatigue protocol. The GFI is influenced by the resistance of cycling to support the equivalent dosage. This study concluded that the mechanism of fatigue would be influenced by the resistance of fatigue protocol although the total works had been controlled.

Keywords: bicycling; central fatigue; exercise; maximal voluntary contraction; peripheral fatigue.