Key result
Higher leg muscle mass linked to lower gross mechanical efficiency during moderate-intensity cycling.
Why the study?
Does higher leg muscle mass reduce gross mechanical efficiency during moderate intensity cycling in young healthy men?
Cross-Sectional (n=12)
No
Does higher leg muscle mass reduce gross mechanical efficiency during moderate intensity cycling in young healthy men?
Greater leg muscle mass in young healthy men is associated with poorer gross mechanical efficiency during moderate-intensity cycling due to higher basal oxygen consumption and internal work costs.
Challenges notion that more muscle mass aids efficiency; observational data leave causal and practical implications open for further study.
Twelve healthy untrained men (age 22 ± 1 years; body mass (BM) 76.8 ± 14.4 kg; height 180 ± 8 cm, (mean ± SD)), participated in this study. The subjects performed an incremental exercise test on a cycloergometer with an increase of power output (PO) by 30 W every 3 min – until exhaustion. Gross mechanical efficiency (GE) and delta efficiency (DE) during exercise of moderate-intensity (below lactate threshold – < LT) was calculated. Both legs muscle mass (LMM) (determined using 3T MRI) amounted to 14.1 ± 2.1 kg (i.e., 18.6% of body mass). Pulmonary oxygen consumption (V̇O2) at rest (sitting position) was 391 ± 42 mL min−1. The slope of the V̇O2(PO) relationship (at the PO’s < LT) amounted to 10.25 ± 0.99 mL O2 min−1 W−1 and the intercept 501 ± 130 mL min−1. Pulmonary maximal oxygen uptake (V̇O2max) was 3198 ± 458 mL O2 min−1, 42.2 ± 5.7 mL O2 min−1 kg−1 BM and 187 ± 30 mL O2 min−1 kg−1 of LMM. The LMM was positively correlated with the V̇O2 at rest (p = 0.01). No relation between the LMM and the DE was found, whereas GE at the PO of 30–90 W was negatively correlated with the LMM (p ≤ 0.05). We concluded that greater muscle mass is not favorable when performing moderate-intensity cycling, since it results in poorer gross muscle mechanical efficiency.
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Żołądź et al. (2025) conducted a cross-sectional in Healthy untrained men (n=12). Incremental exercise test on a cycloergometer was evaluated on Correlation between legs muscle mass and gross mechanical efficiency (GE) at 30-90 W (p=≤0.05). Higher legs muscle mass in young healthy men is negatively correlated with gross mechanical efficiency during moderate-intensity cycling.
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