Electromyogram and signal complexity to evaluate effects of beta-alanine supplementation in the progress to fatigue in cyclic contractions

• Grant number: 17/02183-6
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2017
• End date: February 28, 2019
• Field of knowledge: Biological Sciences - Physiology - Physiology of Effort
• Principal Investigator: José Guilherme de Souza Chaui Mattos Berlinck
• Grantee: José Guilherme de Souza Chaui Mattos Berlinck
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Bruno Gualano

Abstract

Muscle fatigue is a scientific open question. Its causal factors are diverse and the intracellular fall in pH due to the contractile activity plays a major role. Carnosine, a dipeptide formed by L-histidine and b-alanine, is found in skeletal muscles and is an important pH-buffering agent. In this scenario, b-alanine supplementation becomes relevant since an increase in cytoplasmic carnosine might improve buffering capacity and thus postpone fatigue. Some studies have shown an improvement in performance during high intensity activities in face of induced increase in muscle carnosine, indeed. Surface electromyography allows real time study of muscular activity, and a compression of the spectrum towards low frequencies is a known feature of electromyography changes associated to fatigue. However, the underlying biological phenomena that might cause such changes are not yet completely known. Nonlinear methods are increasingly employed to characterize Complexity in biological time-series. In the context of fatigue, some studies have shown a decrease in complexity of the electromyographic signal due to continuous volunteer contraction of muscles. We put, therefore, the following query: is there a difference in the electromyography response of fatigue in face of cyclic volunteer activation to exhaustion in muscles composed by different proportions of type-I and type-II fibers due to b-alanine supplementation? The present research proposal intends to approach such a question employing electromyography and complexity measures of the signal to characterize both the road to fatigue and associated changes in the underlying processes of muscle contraction control. (AU)