Effects of 1,144 km of road cycling performed in 7 days: a cardiometabolic imaging study.

This cardiometabolic imaging study was designed to document the adaptation of middle-aged recreational cyclists to a large exercise prescription not aiming at weight loss. Eleven middle-aged recreational male cyclists traveled 1,144 km over seven consecutive days. A comprehensive cardiometabolic profile including visceral and ectopic adiposity assessed by magnetic resonance imaging was obtained at baseline and following the exercise week. Cardiorespiratory fitness (CRF) was measured using maximal cardiopulmonary exercise testing. During the week, heart rate was monitored to calculate individual energy expenditure. Baseline characteristics of cyclists were compared with 86 healthy males in the same age range. Cyclists presented higher baseline CRF (+9.2 mL/kg/min, P < 0.0001) and lower subcutaneous (-56.2 mL, P < 0.05) and liver (-3.3%, P < 0.05) fat compared with the reference group. Despite the large energy expenditure during the cycling week, the increase in energy intake limited decreases in body weight (-0.8 ± 0.9 kg, P < 0.05) and body mass index (-0.3 ± 0.3 kg/m², P < 0.05). Loss of fat mass (-1.5 ± 1.0 kg, P < 0.001) and a trend toward an increased lean mass (+0.8 ± 1.2 kg, P < 0.07) were observed. Visceral adiposity (-14.1 ± 14.2 mL, P < 0.01) and waist circumference (-3.2 ± 1.7 cm, P < 0.0001) decreased, whereas subcutaneous (-2.7 ± 5.1 mL, NS), liver (-0.5 ± 0.9%, NS), and cardiac (-0.3 ± 2.3 mL, NS) fat remained unchanged. This cardiometabolic imaging study documents middle-aged recreational cyclists' subcutaneous and visceral adiposity as well as cardiac and liver fat responses to a large volume of endurance exercise despite an increase in energy intake aimed at limiting weight loss.NEW & NOTEWORTHY Even when being accompanied by a substantial increase in energy intake to compensate energy expenditure and limit weight loss, a large volume of endurance exercise performed within a short period of time is associated with a significant reduction in visceral adiposity. High cardiorespiratory fitness is associated with low levels of liver fat in middle-aged males.