The Tensiomiography Amplitude Stimulation Influences the Interpretation of the Rectus Femoris Neuromuscular Status After a Repeated Sprint Training

Abstract

This study aimed to analyze the relationship between the muscle contractile properties (MCP), before and after performing several bouts of repeated sprints, measured at different neuromuscular electrical stimulation (NMES) amplitudes. Twenty-two male participants participated on this study (age = 23.2 ± 9.8 years, height = 1.75 ± 0.01 m, body mass) 72.7 ± 21.0 kg). Testing consisted of creatine kinase (CK) measurement, tensiomyography (TMG), and maximal voluntary isometric contraction (MVIC). We first collected a fingertip capillary blood sample for the CK determination after 10 min of remaining in a seated position. Secondly, we conducted a TMG test on each limb in the Rectus Femoris (RF). Then, participants performed 6 maximal 30 m repeated sprints (RS) with a 30 s recovery. Pre-intervention, the highest correlations (p < 0.05) were found between muscle displacement stimulated at 40 mA and RS-change (r b = -0.65), RS-Loss (r b = -0.66) and RS-Fatigue (r b = -0.55). Superior NMES amplitude decreased the magnitude of the correlation. After the intervention, the highest correlations were found with an amplitude of 60 mA between muscle displacement and RS-change (r b = -0.61), RS-Loss (r b = -0.57), and RS-Fatigue (r b = -0.50). These results suggest that measuring the TMG until the Dm-max point can lead to misinterpretations of the MCP behavior in response to transient fatigue.