Validity of Average Power, Total Work, and Exercise Energy Expenditure Quantified by Cycling Mechanics.

Abstract: Oosthuyse, T, Bownes, N, Wiemers, LA, and Bosch, AN. Validity of average power, total work, and exercise energy expenditure quantified by cycling mechanics. J Strength Cond Res XX(X): 000-000, 2025-Average power, work, and exercise energy expenditure (EEE) are useful metrics in cycling for gauging training load and targeting energy intake. These metrics are easily obtained from bicycle-mounted power meters but not all cyclists train with power meters. We used the laws of mechanics to estimate average power, total work, and EEE compared with power-meter measurements during n = 100 training sessions (n = 32 on road bicycles; n = 68 on mountain bikes [MTBs]) in competitive cyclists, with p < 0.05 as significant. Physics-derived average power and power-meter measures had a good agreement (Watts, mean difference ± SD -1.04 ± 10.38; SEM 1.038; coefficient of variability 4.2%; intraclass correlation coefficient 0.93), producing estimates of total work (-2 ± 24 kcal) and EEE (-10 ± 120 kcal) with negligible mean differences. Although average power was similar (MTB: 2.21 ± 0.31 W·kg-1; road: 2.24 ± 0.34 W·kg-1), total force produced (FTotal) was greater in MTB than in road training (25.8 ± 4.6 N; 20.7 ± 3.0 N). The components of FTotal differed, where forces to overcome gradient (12.9 ± 5.2 N; 8.5 ± 3.1 N) and rolling resistance (8.2 ± 1.6 N; 3.9 ± 1.1 N) were greater in MTB, and frictional air drag (4.7 ± 1.9 N; 8.4 ± 2.3 N) was greater in road training. Using the methodology applied, the laws of cycling mechanics produce fair measures of average power, total work, and EEE for cyclists without bicycle-mounted power meters. In addition, deriving the respective force components could support training prescription and equipment adjustments to optimize performance.