(37) CEREBRAL OXYGENATION RESPONSES TO ARM AND LEG CYCLING PERFORMED AT MODERATE AND HEAVY INTENSITIES

Purpose: Cerebral oxygenation response during cardiorespiratory exercise is influenced by various factors, including exercise intensity, duration, individual fitness level, and the presence of any underlying health conditions. However, the effect of cardiorespiratory exercise mode involving major upper and lower body skeletal muscle groups on cerebral oxygenation remains to be further explored. This study examined the prefrontal cortex oxygenated hemoglobin concentrations before, during, and after an isocaloric exercise session performed at moderate and heavy intensity exercise domains.

Methods: Participants (16 females and 14 males), 23 ± 4 years old, body mass index of 25 ± 5, completed two visits to determine the gas exchange threshold (GET) for arm and leg cycling. Four additional randomized and counterbalanced visits for arm and leg cycling at moderate (i.e., below GET) and at heavy (i.e., above GET) intensity completed to 100 kcals were used to investigate the prefrontal responses of oxygenated hemoglobin utilizing near-infrared spectroscopy. These were measured before, during, and post-test. Mixed effect models were used to quantify the fixed effects of mode (arm- vs. leg cycling), intensity (moderate vs. heavy), and condition (rest vs. exercise vs. post-test) on oxygenated hemoglobin, with participants as a random effect. Significance was considered as p< 0.05, and effect sizes were quantified and interpreted as pseudo R² and semipartial R².

Results: No significant interaction existed between mode, intensity, and condition (p = 0.179). There was no significant interaction between mode and condition (p = 0.328) or mode and intensity (p = 0.117). There was no significant main effect of intensity (p = 0.585). However, there was a significant interaction between intensity and condition (p = 0.015). There was also a significant main effect of condition (p < 0.001). The most parsimonious model contained the interaction between intensity and condition and main effects of intensity and condition (marginal effect R² = 0.650; condition semipartial R² = 0.529; intensity semipartial R² = 0.013; intensity*condition semipartial R² = 0.022).

Conclusions: These data suggest no significant difference in prefrontal cortex oxygenation between cardiorespiratory exercises involving major upper and lower body skeletal muscle groups. Furthermore, cerebral oxygenation remained significantly higher post-test than the initial resting condition, with a small effect size for oxygenated hemoglobin after heavy (71%) compared to moderate (66%) cardiorespiratory exercise.

PRACTICAL APPLICATIONS: Healthy individuals performing either arm or leg cycling with a duration necessary to expend 100 kcals at moderate or heavy exercise intensities should not expect significant differences in cerebral oxygenation. However, considerable increases in cerebral oxygenation of approximately 45% should be expected in short-term rest post either exercise modes.


Acknowledgements:

This study was partially funded by the College of Graduate Studies and the College of Community Innovation and Education at the University of Central Florida.