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

## TL;DR

This study found no significant link between phase angle, a marker of cellular health, and cycling efficiency or economy in young adults.

## Contribution

This is the first pilot study to investigate the relationship between phase angle and cycling efficiency in healthy individuals.

## Key findings

- Phase angle was not significantly correlated with delta efficiency, gross efficiency, or exercise economy.
- Regression models confirmed that phase angle did not independently predict cycling efficiency or economy.
- No significant differences in performance indicators were found between high and low phase angle groups.

## Abstract

Phase angle (PhA), derived from bioelectrical impedance analysis (BIA), is considered a non-invasive marker of cellular health and membrane integrity. Whether PhA relates to muscular efficiency during exercise remains unclear.

This pilot study investigated the association between PhA and delta efficiency (DE), gross efficiency (GE), and exercise economy (EC) during submaximal cycling in 30 healthy young adults (15 females, mean age 21.4 ± 3.8 years). Whole-body and lower-body PhA were assessed using multifrequency BIA. Participants completed a graded cycling test (20–80 W) with energy expenditure determined via indirect calorimetry. DE, GE, and EC were calculated using standard procedures, and associations with PhA were examined using Pearson correlations, median-split group comparisons, and multivariable linear regression models adjusting for sex and fat-free mass.

Neither whole-body nor lower-body PhA was significantly correlated with DE, GE, or EC (all p > 0.05). Group comparisons based on PhA medians showed no significant differences in performance indicators. The largest observed correlation was between whole-body PhA and GE (r = −0.32, p = 0.081). Regression models adjusting for sex and fat-free mass confirmed that PhA did not independently predict DE, GE, or EC.

PhA did not predict submaximal cycling efficiency or economy in healthy young adults. These findings suggest that cellular health, as reflected by PhA, may not directly influence muscular energetics under steady-state conditions. Future studies with larger samples and mechanistic measurements are warranted to clarify this relationship.