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

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 39(11): 1138-1147, 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.