Changes in Skinfold Thicknesses and Body Fat in Ultra-endurance Cyclists

Purpose: The present study investigated the changes in single skinfold thicknesses and body fat during an ultra-endurance cycling race. Methods: One hundred and nineteen ultra-endurance cyclists in the ‘Swiss Cycling Marathon’ covering a distance of 600 km were included. Changes in skinfold thickness, fat mass, skeletal muscle mass and total body water were estimated using anthropometric methods. Results: The subjects were riding at a mean speed of 23.5±4.0 km/h and finished the race within 1,580±296 min. During the race, body mass decreased by 1.5±1.2 kg (P<0.001), and fat mass decreased by 1.5±1.1 kg (P<0.001). Skeletal muscle mass and total body water remained unchanged (P>0.05). The decrease in body mass correlated to the decrease in fat mass (r = 0.20, P=0.03). The skinfold thicknesses at pectoral (-14.7%), abdominal (-14.9%), and thigh (-10.2%) site showed the largest decrease. The decrease in abdominal skinfold was significantly and negatively related to cycling speed during the race (r = -0.31, P<0.001). Conclusion: Cycling 600 km at ~23 km/h led to a decrease in fat mass and in all skinfold thicknesses. The largest decrease in skinfold thickness was recorded for pectoral, abdominal, and thigh site. The decrease in abdominal skinfold thickness was negatively related to cycling speed. The body seems to reduce adipose subcutaneous fat during an ultra-endurance performance at the site of the thickest skinfold.