During cycling exercise, at least 75% of energy expended is wasted as heat or used to maintain homeostasis regard to the consistent value of gross efficiency (GE), net efficiency (NE) and delta efficiency (DE) reported in the literature (18-26%). Therefore, it would be assumed that a potential link exist between cycling efficiency and thermoregulationprocess.Skin temperature of two lower limb muscle's group (quadriceps and calves) detected by infrared camera and cycling efficiency parameters determined by gas exchanges analysis were measured during a graded exercise test until exhaustion in seven trained cyclists. Unlike to Unlike to GE (median (interquartile range) 19.8 (2.0) %) and NE (22.4 (3.3)%), DE (26.1 (2.7)%) was significantly inverse correlated (r =-0.821; p = 0.034) with relative (-8.6 (1.9)%) changes in skin temperature over VL when power output increases from 100 to 300 W. These results suggested that even if GE and NE were unrelated to the thermoregulation effectiveness, DE seems to be higher in cyclists who showed the highest variation of skin temperature over the quadriceps muscle.