Neuromuscular fatigue and recovery profiles in individuals with intellectual disability

Rihab Borji; Firas Zghal; Nidhal Zarrouk; Vincent Martin; Sonia Sahli; Haithem Rebai

doi:10.1016/j.jshs.2017.03.015

Neuromuscular fatigue and recovery profiles in individuals with intellectual disability

J Sport Health Sci. 2019 May;8(3):242-248. doi: 10.1016/j.jshs.2017.03.015. Epub 2017 Mar 31.

Authors

Rihab Borji¹, Firas Zghal¹, Nidhal Zarrouk¹, Vincent Martin², Sonia Sahli¹, Haithem Rebai¹

Affiliations

¹ Research Unit Education, Motor Skills, Sports and Health (EM2S, UR15JS01), Higher Institute of Sport and Physical Education of Sfax, University of Sfax, Sfax 3000, Tunisia.
² Laboratory of Metabolic Adaptations to Exercise in Physiological and Pathological Conditions, Blaise Pascal University, Clermont-Ferrand 63000, France.

Abstract

Purpose: This study aimed to explore neuromuscular fatigue and recovery profiles in individuals with intellectual disability (ID) after exhausting submaximal contraction.

Methods: Ten men with ID were compared to 10 men without ID. The evaluation of neuromuscular function consisted in brief (3 s) isometric maximal voluntary contraction (IMVC) of the knee extension superimposed with electrical nerve stimulation before, immediately after, and during 33 min after an exhausting submaximal isometric task at 15% of the IMVC. Force, voluntary activation level (VAL), potentiated twitch (Ptw), and electromyography (EMG) signals were measured during IMVC and then analyzed.

Results: Individuals with ID developed lower baseline IMVC, VAL, Ptw, and RMS/M_max ratio (root-mean-square value normalized to the maximal peak-to-peak amplitude of the M-wave) than controls (p < 0.05). Nevertheless, the time to task failure was significantly longer in ID vs. controls (p < 0.05). The 2 groups presented similar IMVC decline and recovery kinetics after the fatiguing exercise. However, individuals with ID presented higher VAL and RMS/M_max ratio declines but lower Ptw decline compared to those without ID. Moreover, individuals with ID demonstrated a persistent central fatigue but faster recovery from peripheral fatigue.

Conclusion: These differences in neuromuscular fatigue profiles and recovery kinetics should be acknowledged when prescribing training programs for individuals with ID.

Keywords: Central fatigue; Intellectual disability; Neuromuscular fatigue; Peripheral fatigue; Sustained sub-maximal exercise; Twitch interpolation technique.