Body mass scaling of endurance cycling performance

• Main Author: Heil, Daniel Paul
• Language: ENG
• Published: ScholarWorks@UMass Amherst 1997
• Subjects: Physical education|Sports medicine
• Online Access: https://scholarworks.umass.edu/dissertations/AAI9737536

The purpose of this dissertation was to assess the relationship between body mass (M$\rm\sb{B})$ and endurance cycling performance. Four experiments were designed to describe the relationship between a dependent variable (Y) and M$\rm\sb{B}$ using multiple log-linear regression analysis procedures. Each analysis was used to conclude that Y changed proportionally with M$\rm\sb{B}$ raised to the power of b (i.e. $\rm Y\propto M\sbsp{B}{b}),$ where b is the M$\rm\sb{B}$ exponent. Experiment I utilized a preexisting data set from subjects aged 20-79 years to determine that peak oxygen uptake (VO$\sb{2PEAK}$) scaled with M$\rm\sb{B}$ to the 0.75 (95% CI: 0.651-0.862) power in a heterogeneous population and 0.65 (0.530-0.775) power in a homogeneous population. These findings were shown to be consistent with predictions from the theory of geometry similarity (TGS). Experiment II evaluated how net VO$\sb2$ (VO$\rm\sb{2(NET)})$ scaled with M$\rm\sb{B}$ as well as the combined mass (M$\rm\sb{C})$ of the cyclist and bicycle and M$\rm\sb{B}$ during uphill treadmill bicycling. It was concluded that VO$\rm\sb{2(NET)}\propto M\sbsp{C}{1.0}$ due to gravitational resistance, while VO$\rm\sb{2(NET)}\propto M\sbsp{B}{0.89}$ because the cyclists' bicycles were relatively lighter for heavier cyclists. Experiment III determined that the scaling relationship between projected frontal area (A$\rm\sb{p})$ and body mass. Both body A$\rm\sb{p}$ (A$\rm\sb{p}$ for cyclist's body) and total A$\rm\sb{p}$ (A$\rm\sb{p}$ for cyclist's body and bicycle) scaled with M$\rm\sb{B}$ to powers significantly lower (0.408 (95% CI: 0.299-0.517) and 0.463 (0.262-0.663), respectively) than the 0.67 power predicted for area measurements by the TGS. This indicates that larger cyclists should experience less aerodynamic drag relative to their body mass than smaller cyclists at a constant ground speed. Lastly, results from Experiments I-III were combined with data from the literature to derive and validate a generalized allometric model (GAM) of endurance cycling performance in Experiment IV. The GAM equated the metabolic power supply and external power demands of time-trial cycling performance in a mathematical model expressed exclusively in terms of M$\rm\sb{B}$ differences. The model results appeared consistent with anecdotal observations and valid when compared to actual time-trial data. The results of this dissertation support the use of M$\rm\sb{B}$ scaling as a tool for better understanding of body mass as a determinant of human performance.