Effect of pedal cadence on the heterogeneity of muscle deoxygenation during moderate exercise

Abstract

This study examined the effect of pedal cadence on the heterogeneity of muscle deoxygenation during exercise of moderate intensity. Twelve healthy subjects performed 6 min of cycling at 40 and 100 r · min(-1) at 80% of the workload corresponding to the gas exchange threshold. Gas exchanges were measured breath by breath during each exercise. Muscle deoxygenation (HHb, i.e., O2 extraction) was monitored continuously by near-infrared spectroscopy at eight sites on the vastus lateralis. The heterogeneity of HHb was assessed using the relative dispersion of the signal measured at the eight sites (i.e., 100 × standard deviation/mean). HHb was not altered by the pedal cadence, whereas pulmonary V̇O2 was higher at 100 r · min(-1) than at 40 r · min(-1) (p < 0.001). The relative dispersion of HHb was significantly higher at 100 r · min(-1) than at 40 r · min(-1) (p < 0.001). These results indicate that pedal cadence has no effect on O2 extraction but that an elevated cadence would increase muscle V̇O2, suggesting an increase in muscle blood flow. Elevated cadence also induced greater heterogeneity of the muscle's V̇O2/Q̇O2 delivery ratio, suggesting a change in the adequacy between O2 demand and O2 delivery in some regions of active muscle.

Effect of pedaling cadence on muscle oxygenation during high-intensity cycling until exhaustion: a comparison between untrained subjects and triathletes

“…To our knowledge, this is the first study that shows this result. Indeed, previous studies that have an interest in the effect of pedaling cadence on muscle deoxygenation reported a similar level of extraction independently of the cadence (Ferreira et al 2006;Kounalakis and Geladas 2012;Zorgati et al 2013) or increased muscle O 2 extraction with increasing cadence (Boone et al 2014). These differences could be partly explained by the modality (progressive vs. constant work rate exercise in our study) or intensity of the exercise (moderate vs. heavy in the present study).…”

“…However, other studies have pointed out a decrease in Q M with increasing contraction frequency during a knee extension exercise limited to 20° of angular movement from 90° (Hoelting et al 2001). On the other hand, previous studies that were interested in the effect of pedaling cadence on muscle oxygenation, by using near-infrared spectroscopy technology (NIRS), reported a similar level of O 2 extraction independently of the cadence during incremental exercise (Ferreira et al 2006) and during moderate exercise (Kounalakis and Geladas 2012;Zorgati et al 2013). Nevertheless, Boone et al (2014) observed a greater muscle O 2 extraction at the highest pedaling cadence during incremental ramp exercise.…”

“…Indeed, some studies did not observe an effect of pedaling cadence on V O 2 (Barstow et al 1996;Foss and Hallen 2004;Hill and Vingren 2012;Zoladz et al 2002). However, other studies showed a higher V O 2 at the same work rate for cycling at a higher pedal cadence (Chavarren and Calbet 1999;Coast and Welch 1985;Gaesser and Brooks 1975;Nesi et al 2004;Tokui and Hirakoba 2008;Zorgati et al 2013). It seems that the effect of cadence on wholebody V O 2 was reduced at high power outputs which could also be the case at the muscular level [i.e., muscle V O 2 (V O 2M )].…”

“…Although several studies have been interested in the effect of pedaling cadence on performance, to our knowledge, no study focused the attention on muscle oxygenation during heavy exercise until exhaustion at two different cadences. Indeed, the few studies that have examined the effect of the pedaling cadence on muscle oxygenation have used incremental exercise (Boone et al 2014;Ferreira et al 2006) or moderate constant load exercise (Kounalakis and Geladas 2012;Zorgati et al 2013). However, the kinetics of the O 2 extraction during incremental exercise is complex (Boone et al 2009) and the effect of pedaling cadence on the muscle oxygenation responses during constant load exercise could be different.…”

“…When studying the effect of the pedaling cadence, these previous works were performed in subjects who were not endurance trained (Boone et al 2014;Ferreira et al 2006;Kounalakis and Geladas 2012;Zorgati et al 2013). In muscle, endurance training is associated with increased activity of key enzymes of the mitochondrial electron transport chain, an increase in mitochondrial protein concentration and an increase in capillary supply.…”