Maximum voluntary muscle contraction and fatigue in multibacillary leprosy

Abstract

Introduction: The impairment of muscle strength and fatigue in leprosy remains a problem that requires careful attention to avoid or minimize its progression, as well as prevention of disabilities and deformities. Objective: To investigate the maximum voluntary contraction and time to muscle fatigue in leprosy patients. Method: A total of 21 leprosy patients and 21 healthy subjects completed the sample. The method used to determine the maximum voluntary contraction (MVC) of the handgrip followed the recommendation of the American Society of Hand Therapists with the use of a hydraulic hand grip dynamometer. The test was performed three times with each hand, with a time interval of 60 seconds between successive trials. The subject was instructed to perform a maximal isometric force against the dynamometer for 5 seconds. The peaks were recorded and used for the fatigue test. For the fatigue test, we recorded the electromyogram of the forearm muscles to offline determine the onset time for the muscle contraction (14 bits, Miograph 2 USB®, Miotec, Brazil). Results: Leprosy patients had lower MVC compared with healthy subjects (p < 0.05), both in the dominant and the non-dominant hands. The time to fatigue in the leprosy and control groups was similar (p > 0.05). We observed that leprosy patients had more contractions than the healthy subjects (22.6 ± 11.8 contractions for the leprosy group vs. 12.3 ± 6.9 contractions for the control group, p < 0.05). Conclusion: Multibacillary leprosy patients lost muscle force without modifying the resistance to fatigue.