Clustering classification of cyclists according to acute fatigue outcomes produced by an ultra-endurance event

This study aimed to analyze the differences between clusters obtained by the acute fatigue effect following an ultra-endurance event on the internal and external load of cyclists. 26 volunteers participated in the study, divided into the experimental group (N = 18; height: 177 & PLUSMN; 8 cm; body mass: 78.6 & PLUSMN; 10.3 kg) and the control group (N = 8; height: 176 & PLUSMN; 10 cm; body mass: 78.0 & PLUSMN; 15.7 kg). The experimental group completed a 12 h non-stop cycling event. Jump height, lactate, plasma antioxidant capacity, pain perception and fatigue perception were measured before and after the event. Cyclists of the experimental group were classified taking into account their training characteristics (recreational vs. competitive) and conducting non-supervised K -means clustering. The differentiation of cyclists according to training characteristics resulted in a lower distance covered by recreational cyclists than competitive cyclists (279.4 & PLUSMN; 39.7 km vs. 371.0 & PLUSMN; 71.7 km; ES & GE; 0.8; p < 0.01), although no differences were observed in the other variables between groups (p > 0.05). The clustering analysis resulted in two clusters. Cluster 2 suffered a greater jump height decrease (-3.3 & PLUSMN; 1.6 vs. 1.2 & PLUSMN; 0.8; ES & GE; 0.8; p < 0.001) and increased pain and fatigue perception (ES & GE; 0.5; p < 0.05) after the race than Cluster 1. In conclusion, counter-movement jump and fatigue/pain perception can differentiate the fatigue produced by a cycling ultra-endurance event and therefore, these non-invasive measurements are useful in fatigue monitoring and recovery planning.