Dolores G. Ortega^1,, Robert W. Smith¹, Jocelyn E. Arnett¹, Tyler J. Neltner², Trevor D. Roberts¹, Richard J. Schmidt¹, Glen O. Johnson¹, Terry J. Housh¹

The purpose of this study was to examine the effects of anchor scheme (RPE vs. torque) on the composite, inter- and intra-individual torque and neuromuscular patterns of responses (PoR) during fatiguing forearm flexion tasks. Twelve men (mean±SD: age=20.9±2.2 yrs.; height=179.8±5.3 cm; body mass=80.2±9.9 kg) performed maximal voluntary isometric contractions (MVIC) before and after sustained, isometric forearm flexion tasks to failure anchored to RPE=4 (RPEFT) and the torque (TRQFT) that corresponded to RPE=4. The amplitude (AMP) and mean power frequency (MPF) of the electromyographic and mechanomyographic (MMG) signals were recorded from the biceps brachii. Polynomial regression analyses were used to define the individual and composite relationships for normalized torque and neuromuscular parameters versus normalized time. Dependent t-tests were used to determine mean differences for time to task failure (TTF) and performance fatigability (PF=% decline in MVIC). The RPEFT had a greater TTF (p=0.006), but lower PF (p<0.001) than the TRQFT. During the RPEFT, the composite PoR indicated significant (p≤0.05) linear decreases for torque, EMG MPF, MMG MPF, and NME, a linear increase for MMG AMP, and no relationship for EMG AMP. During the TRQFT, the composite PoR indicated significant (p≤0.05) linear decreases for EMG MPF, MMG MPF, and NME, linear increases in EMG AMP and MMG AMP, and no relationship for torque. The individual PoR indicated substantial variability within and between anchor schemes. These findings indicated that TTF and PF as well as the composite, inter-, and intra-individual PoR were dependent on the anchor scheme of the fatiguing task.

ratings of perceived exertion, upper body, electromyography, mechanomyography