Perceived Exertion During Endurance Tasks of Abdominal Muscles vs. Electrophysiological Signs of Fatigue—Are They Interchangeable?

Abdominal muscles play a crucial role in spinal stability which may be altered by muscular fatigue. To assess the extent of current fatigue, subjective and objective parameters can be used. The aim of the present study was to investigate whether different perceived exertion levels correspond with changes in fatigue-associated electrophysiological parameters of abdominal muscles. For this, 34 healthy participants (17 women) underwent a 10 min static endurance task of their abdominal muscles at 50% upper body weight. Every elapsed minute, perceived exertion was assessed together with changes in electro-physiological parameters. Based on the perceived exertion levels, participants were divided into a “good end” and a “bad end” group. Independent of group, muscular fatigue was identified in all abdominal muscles. In the rectus abdominis muscle this was most pronounced, with different levels between groups and satisfactory correlations between perceived exertion levels and electrophysiological parameters. Thus, electrophysiological signs of fatigue and RPE levels are interchangeable for the rectus abdominis. In contrast and therefore of utmost importance, fatigue of the oblique abdominal muscles is largely unrelated to perceived exertion. Given the key role of these muscles in maintaining trunk stability, prolonged submaximal loads appear to affect their function regardless of mild or intense exertion level.