The Influence of Exercise Intensity on the Association Between kJ Spent and Various Training Loads in Professional Cycling

A valid measure for training load (TL) is an important tool for cyclists, trainers and sport scientists involved in professional cycling. The aim of this study is to explore the influence of exercise intensity on the association between kJ spent and different measures of TL to arrive at valid measures of TL. Four years of field data were collected from 21 cyclists of a professional cycling team, including 11,716 training and race sessions. kJ spent was obtained from power output measurements and others TL's were calculated based on the session Rating of Perceived Exertion (sRPE), heart rate (luTRIMP) and power output (TSS). Exercise intensity was expressed by the intensity factor (IF). To study the effect of exercise intensity on the association between kJ spent and various other TL's (sRPE, luTRIMP and TSS), data from low and high intensity sessions were subjected to regression analyses using generalized estimating equations (GEE). This study shows that the IF is significantly different for training and race sessions (0.59±0.03 vs. 0.73±0.03). Significant regression coefficients show that kJ spent is a good predictor of sRPE, luTRIMP, as well as TSS. However, IF does not influence the associations between kJ spent and sRPE and luTRIMP, while the association with TSS is different when sessions are done with low or high IF. It seems that the TSS reacts differently to exercise intensity than sRPE and luTRIMP. A possible explanation could be the quadratic relation between IF and TSS.