Errors in Force Generation and Changes in Controlling Patterns Following Agonist Muscle Fatigue

in Journal of Applied Biomechanics
Restricted access

Purchase article

USD  $24.95

Student 1 year subscription

USD  $87.00

1 year subscription

USD  $116.00

Student 2 year subscription

USD  $165.00

2 year subscription

USD  $215.00

The purpose of this study was to evaluate whether agonist muscle fatigue changed the coactivation time and the co-contraction magnitude of the agonist and antagonist muscle, and if the agonist muscle fatigue produced bias (constant error: CE) and inconsistency (variable error: VE) of the force. Subjects are 10 healthy people and one person with impaired proprioception. EMG and force for fast (0.19 ± 0.06 s) and slow (1.20 ± 0.44 s) targeted isometric dorsiflexions were recorded before and after fatigue of the dorsiflexors. The results revealed that the coactivation time increased after fatigue only in the slow contractions but the co-contraction magnitude did not change. The postfatigue increment of the CE was greater in the fast contractions than in the slow ones. We conclude that the postfatigue compensatory strategy can reduce the fatigue-induced bias. The change of muscles activation level after fatigue might be under the influence of the common drive. Impaired proprioception is a possible cause of the fatigue-related increase in bias and inconsistency.

Huang is with the Graduate Institute of Coaching Science, National College of Physical Education and Sports, Tao-Yuan, Taiwan. Chang (Corresponding Author) is with the Physical Therapy Department and the Graduate Institute of Rehabilitation Science, Chang Gung University, Tao-Yuan, Taiwan. Hsu is with the Faculty of Physical Therapy, Kaohsiung Medical University, and the Department of Rehabilitation, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan. Chen is with the Physical Therapy Department and the Graduate Institute of Rehabilitation Science, Chang Gung University, Tao-Yuan, Taiwan. Fang is with the Department of Rehabilitation Technology, Tzu-Hui Institute of Technology, Ping-Tung, Taiwan; Wong is with the Physical Therapy Department and the Graduate Institute of Rehabilitation Science, Chang Gung University, Tao-Yuan, Taiwan.