Ultra-endurance sports have gained popularity over the last years. In this case, a well-trained cyclist completed 503.5 km non-stop (33.3 km.h-1). Speed and power output were reduced during the trial, being the reduction of power attributable to changes in pedal velocity rather than pedal forces. Heart rate (HR) showed an initial cardiovascular drift and progressively decreased independently of power. A decreased HR variability, a marked inflammatory response, signs of muscle damage and alterations of the haematological profile were observed after the trial. These adverse physiological effects were still present 24-48 h after exercise. A reduction in handgrip maximal voluntary contraction was observed immediately after the trial and 24 h later despite these muscles being minimally active during exercise. These findings show the high levels of stress to which the organism is subjected during ultra-endurance exercise even in the case of a trained cyclist.
Keywords: Ultra-endurance; biochemical changes; cardiovascular response; heart rate variability.