Cycling exercise efficiency and economy: Exploring the role of phase angle

Area of Science:

• Exercise Physiology
• Biophysics
• Biomarkers

Background:

• Phase angle (PhA) from bioelectrical impedance analysis (BIA) indicates cellular health and membrane integrity.
• The relationship between PhA and muscular efficiency during exercise is not well understood.

Purpose of the Study:

• To investigate the association between PhA and measures of muscular efficiency (delta efficiency, gross efficiency) and exercise economy during submaximal cycling.
• To determine if PhA can predict exercise performance in healthy young adults.

Main Methods:

• A pilot study involving 30 healthy young adults (15 females).
• Whole-body and lower-body PhA measured using multifrequency BIA.
• Submaximal graded cycling test (20-80 W) with indirect calorimetry to assess energy expenditure; delta efficiency, gross efficiency, and exercise economy calculated.

Main Results:

• No significant correlations were found between PhA (whole-body or lower-body) and delta efficiency, gross efficiency, or exercise economy (p > 0.05).
• Group comparisons based on PhA medians revealed no significant differences in performance indicators.
• Multivariable regression models, adjusted for sex and fat-free mass, confirmed PhA did not independently predict these efficiency or economy measures.

Conclusions:

• Phase angle does not appear to predict submaximal cycling efficiency or economy in healthy young adults.
• These findings suggest that cellular health, as indicated by PhA, may not directly influence muscular energetics during steady-state exercise.
• Further research with larger cohorts and mechanistic investigations is needed to fully elucidate the relationship between PhA and exercise physiology.