Abstract
This study examined the muscle oxygen saturation profiles of core and thigh
muscles during cycling and investigated their relationship with gross efficiency
across various cycling intensities. Eleven male cyclists and triathletes
performed a graded exercise test using a cycle ergometer. Muscle oxygen
saturation was measured in the vastus lateralis, biceps femoris long head,
erector spinae, and external oblique muscles at each intensity level, along with
gross efficiency. The percentage of peak power output at which
muscle oxygen saturation began to decrease significantly from the initial load
was 60% in the vastus lateralis, 80% in the biceps femoris long head, and 70% in
both the erector spinae and external oblique muscles (p <0.05 or
p <0.01). In contrast, no significant differences in deoxygenation
between muscles were observed at intensities between 60% and 90% of peak power
output. At 80% of peak power output, a significant positive correlation was
found between gross efficiency and oxygen saturation in the erector spinae
(r =0.745, p <0.01). In conclusion, the oxygen saturation
profile of core muscles are comparable to those of thigh muscles, and oxygen
saturation in the erector spinae may contribute to gross efficiency during
high-intensity cycling.
Keywords Energy expenditure - muscle oxygen utilization - near-infrared spectroscopy - graded
exercise test - moderate-to-high-intensity - amateur cyclists
