Abstract

Introduction: It has been observed that the measurement of skinfolds has a strong relationship with total subcutaneous adipose tissue and intramuscular fat. This accumulation of adipose tissue affects the metabolic capacity and accelerates the appearance of muscle fatigue during functional activities. However, there are few reports investigating the effect of these factors on neuromuscular control and electromyographic recording.The objective of this research was to determine the influence of nutritional status and fatigue on the onset latency of the scapular muscles.Methods: Twenty-four participants were randomly assigned to one of the following groups: non-fatigue and fatigue. Measurements of weight, height, and skinfolds [axillary (AXS), pectoral (PES), triceps (TRS), sub-scapular (SBS), ileocrestal (ICS), abdominal (ABS), and anterior thigh(ATS)] were made, and the percentage of body fat was calculated by theSiri equation, where the body density considered was that proposed byJackson & Pollock. The onset latency of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT) and serratus anterior (SA) muscles was measured with electromyography during an arm raise test. The influence of the nutritional status on the onset latency of each muscle was analyzed through a multiple linear regression model adjusted for the variables: skinfolds (AXS, PES, SBS), body fat percentage, and fatigue. An alpha level < 0.05 was considered in all tests.Results: There were not significant differences in BMI between groups(p > 0.05). The multiple linear regression model showed that UT onset latency was not influenced by skinfolds, percentage of body fat, and fatigue (P > 0.05). In the MT, LT and SA muscles, the presence of fatigue factor was associated with a greater muscle onset latency (Table 1), and the model was not influenced by skinfold (PAX, PPE, and PSB), except for SA which was influenced by the simultaneous presence of PSB and muscle fatigue. Conclusion: Muscle fatigue influences the onset latency of the MT, LT and SA muscles. In SA, the presence of subcutaneous adipose tissue in the subscapular region and the performance of fatiguing tasks influence the onset latency. It is suggested to consider these results for the electromyographic record of the SA muscle.