Skeletal Muscle Deoxygenation Responses During Treadmill Exercise in Children

Abstract

Muscle O₂ saturation (SmO₂) and blood volume response in activating muscles during treadmill exercise were compared between prepubertal boys (n = 9, age: 9 ± 1 years) and young men (n = 9, age: 22 ± 2 years). SmO₂ and blood volume responses were monitored continuously during the exercise at the gastrocnemius medialis muscle by near infrared spatial resolved spectroscopy. SmO₂ was significantly decreased only at peak exercise in the boys, even though a significant decrease in SmO₂ was observed at 60, 80, and 100 % of peak O₂ uptake in the men (p < 0.05). No significant increase in blood volume was observed in the boys, while blood volume was significantly increased in the men with increased exercise intensity (p < 0.05). These results suggest that both blood volume and deoxygenation response in activating muscle may be minor in prepubertal boys, compared to young men. The blunted deoxygenation response in prepubertal boys may be caused by undeveloped diffusive O₂ transport (i.e. mitochondrial respiration).

Accelerated point of muscle deoxygenation during the 20‐m shuttle run test

“…In Japan, the 20mSRT is one of the physical fitness tests adopted by the Ministry of Education, Culture, Sports, Science and Technology and is conducted nationwide. It was demonstrated that children have unique physiological responses to exercise (Takagi et al, 2014;Armstrong et al, 2015;Pitt et al, 2015) and that muscle oxygenation response during treadmill running in children is different from that in adults (Takagi et al, 2014). Therefore, it is necessary to clarify the characteristics of muscle oxygenation profiles during the 20mSRT in children and its relationship with 20mSRT performance.…”