• cycling
• oxidative damage
• metabolic risks
• exercise
• physical

In a recent issue, Lucia et al suggested that an experienced professional cyclist can safely complete the three major cycling stage races (Giro d’Italia, Tour de France, and Vuelta a España) within the same season, over a five month period.¹ The authors reached this conclusion mainly on the basis of heart rate telemetry, showing that the total amount of near maximal exercise in athletes with a predominant team role as domestiques is relatively low and compatible with the high requirements of the three races. Although this observation may be true from a physical point of view, it does not consider several substantial biochemical aspects. A bulk of evidence indicates that strenuous and prolonged physical exercise leads to amplified muscle oxygen use, increased electron flux and leakage through mitochondria, and consequent overproduction of reactive oxygen species (ROS). The excessive ROS generation may overwhelm the scavenger capacity of the main antioxidant defences, inducing oxidative damage to lipids, proteins, and nucleic bases and promoting the development of severe and progressive degenerative disorders, such as aging, cancer, atherosclerosis, diabetes, and neurodegeneration. In addition, the oxidative stress following physical exercise has been associated with overtraining, decreased physical performances, muscular fatigue, inflammation, and damage, leading to a decline in fitness and athletic performance in the short term.² Therefore, although a trained athlete can probably fulfil the physical requirements of the three major cycling stage races over a very limited period of time, we suggest that the unfavourable metabolic effects of the increased ROS generation should be carefully considered and eventually prevented or counteracted. In this respect, we believe that a diet enriched in natural antioxidants from fruits and vegetables or the administration of dietary antioxidant supplements may be advisable in elite athletes routinely engaged in strenuous and prolonged physical exercise.³