Vastus lateralis oxygenation during prolonged cycling in healthy males

Abstract

This study examined the relationship between acute cardiorespiratory and muscle oxygenation and blood volume changes during prolonged exercise. Eight healthy male volunteers (mean maximum oxygen uptake VO(2max) = 41.6 +/- 2.4 mL/kg/min) performed 60 min submaximal cycling at 50% VO(2max). Oxygen uptake VO(2) was measured by indirect spirometry, cardiac output (CO) was estimated using a Portapre, and right vastus lateralis oxyhemoglobin/ myoglobin (oxyHb/Mb), deoxyhemoglobin/myoglobin (deoxyHb/Mb), and total hemoglobin/myoglobin (total Hb/Mb) were recorded using near-infrared spectroscopy (NIRS). After 40 min of exercise, there was a significant increase in VO(2) due to a significantly higher arteriovenous oxygen difference ((a - v)O(2diff). After 30 min of exercise CO remained unchanged, but there was a significant decrease in stroke volume and a proportionate increase in heart rate, thus indicating the occurrence of cardiovascular drift. During the first few minutes of exercise, there was a decline in oxyHb/Mb and total Hb/Mb, whereas deoxyHb/Mb remained unchanged. Thereafter, oxyHb/Mb and total Hb/Mb increased systematically until the termination of exercise while deoxyHb/Mb declined. After 40 min of exercise, these changes were significantly different from the baseline values. There were no significant correlations between the changes in the NIRS variables and systemic VO(2) or mixed (a - v)O(2)diff during exercise. These results suggest that factors other than localized changes in muscle oxygenation and blood volume account for the increased VO(2) during prolonged submaximal exercise.

The role of muscle pump in the development of cardiovascular drift

“…During 40 rpm cycling, the initial increase in HbT was followed by a steady state, from the 30th min onwards, without changes over time. The same course of HbT has already been demonstrated during 60 min of cycling at 50% of V Á O 2 max with 50 rpm, despite the 17% SV decline (Kawaguchi et al 2006). In 80 rpm however, HbT remained near to resting levels at least until 80th min of 80 rpm 10.7 ± 0.8 12.0 ± 0.8 11.8 ± 0.9 10.9 ± 0.8 10 ± 0. revolutions per minute at the same total (internal plus external) work performed.…”

Muscle oxygenation during prolonged electrical stimulation-evoked cycling in paraplegics

“…The relative intensity of voluntary cycling exercise in the current investigation was lower than in previous studies that have employed NIRS. Kawaguchi et al (2006) and Neary et al (2001) exercised individuals at mean heart rates of 130-145 and 177 beatsÁmin -1 , respectively. The AB NIRS data in our study were similar to those of Kawaguchi et al (2006), with only minor changes in oxy-Hb and deoxy-Hb over 40 min of exercise.…”

“…Kawaguchi et al (2006) and Neary et al (2001) exercised individuals at mean heart rates of 130-145 and 177 beatsÁmin -1 , respectively. The AB NIRS data in our study were similar to those of Kawaguchi et al (2006), with only minor changes in oxy-Hb and deoxy-Hb over 40 min of exercise. The lower SO 2 in PARA demonstrates that there was greater oxygen extraction than in AB, but it is not clear whether there was insufficient oxygen supply within the working muscles.…”

Application of “living high-training low” enhances cardiac function and skeletal muscle oxygenation during submaximal exercises in athletes

“…Normoxic exercise performance is highly related to a number of factors that can be altered through various altitude and hypoxic training methods, including increases in the exercise economy 11 , acid-base response in the muscle 29 , skeletal muscle oxygenation 27 , cardiac function 13 , vascular function 30 , and microcirculation 31 as well as oxygen transport capacity (e.g., erythropoiesis) 1 and VO 2max 3 . Considering previous studies related to the improvement of athletic performance via LHTL, Levine and Stray-Gunderson 32 assumed that acclimatization to a moderate altitude (2,500 m) plus training at a low altitude (1,250 m) (LHTL) improves sea-level performance in well-trained runners more than an equivalent sea-level or altitude control.…”