BACKGROUND: The purpose of this study was to evaluate the accuracy of neuromuscular function at submaximal intensities of perceived maximal voluntary isometric contractions (MVIC) pre- and post-MVIC. METHODS: Thirteen healthy females and 15 males were recruited to participate in this study. Subjects were asked to visit the lab for a single visit in which they were seated on a bench with their elbows fixed at 90⁰ of elbow flexion. Subjects were asked to perform 3 submaximal isometric contractions (SVIC) of bilateral elbow flexion at 25, 50, and 75% of their perceived MVIC strength. Force and muscle excitation of the dominant biceps brachii were recorded via a load cell and surface electromyography (EMG), respectively. Following completion of the SVICs, subjects performed 2 MVICs, each separated by 1 minute of rest. Subjects then repeated the same sequence of SVICs after MVIC testing. Peak force (PF) and EMG amplitude (EMGAMP) were calculated during a 500ms window of each contraction where PF occurred. Normalized percent error for EMGAMP (nEMGERROR) and PF (nPFERROR) were calculated by subtracting the normalized EMGAMP and PF (relative to MVIC) from the target intensity (i.e., 25/50/75% MVIC). Separate time (pre/post) × intensity (25/50/75%) × sex (M/F) repeated measures ANOVAs were run for each variable and alpha was set a-priori at 0.05. RESULTS: There were no interaction effects for either dependent variable (p=0.158-0.798). However, there was a significant main effect for intensity for nEMGERROR and nPFERROR (p<0.001 for both). Post-hoc analysis indicated that nEMGERROR and nPFERROR at 25% (nEMGERROR: 11.7±16.4%; nPFERROR: 12.7±-14.8%) was significantly greater than 50% (nEMGERROR: -0.5±17.7%; nPFERROR: -0.6 ±16.5%; p<0.001 for both) and 75% (nEMGERROR: -13.2 ± 17.4%; nPFERROR: -14.0±15.9%; p<0.001 for both), when collapsed across time and sex. Additionally, nEMGERROR and nPFERROR at 50% were significantly greater than 75% (p<0.001 for both). CONCLUSIONS: Our findings suggest that performing an MVIC attempt does not enhance one’s ability to accurately estimate submaximal force. Additionally, subjects consistently underestimated 25% effort, overestimated 75% effort, and slightly underestimated 50% effort. Our data suggests that this phenomenon occurs independent of sex, as similar error patterns of muscle excitation and peak force were seen between males and females across all intensities. FUNDING: This project was funded by the University of South Alabama’s Summer Undergraduate Research Fellowship and Bukstein Fellowship.

This document is currently not available here.