Regional Differences in Skeletal Muscle O2 Dynamics During Body-Weight Resistance Exercise with Slow Movement and Tonic Force Generation.

Abstract

The aim of this study was to investigate the skeletal muscle O2 dynamics during body-weight resistance exercise with slow movement and tonic force generation. Thirteen untrained, healthy, young males performed Bulgarian split squats and push-ups until volitional failure. Relative changes from rest in oxygenated haemoglobin (oxy-Hb) and deoxygenated haemoglobin (deoxy-Hb) concentrations were continuously monitored at the vastus lateralis (VL) and rectus femoris (RF) muscles during squats, and pectoralis major (PM) and triceps brachii (TB) muscles during push-ups using spatial resolved near-infrared spectroscopy oximetry. During the squat exercise, deoxy-Hb continuously increased at RF until failure (10.8±7.0μmol/L), while at VL, deoxy-Hb was relatively maintained during 25-100% of the number of maximum repetitions (18.0±7.4μmol/L at volitional failure). During the push-up exercise, a significant increase in deoxy-Hb was observed during exercise from rest at PM and TB. We found a significant increase in oxy-Hb during exercise at PM (28.1±15.8μmol/L at volitional failure), while at TB, no significant difference was observed from rest (-2.7±13.7μmol/L at volitional failure). Our findings suggest that the deoxygenation patterns during body-weight squat exercise were heterogeneous within the quadriceps muscles. Moreover, differences in O2 dynamics between the trunk and extremity muscles may be partly explained by convective O2 supply during resistance exercise. However, future studies are needed due to inter-individual differences in skills for body-weight resistance exercise.