Change in Femoral Cartilage Cross-Sectional Area After Aerobic and Resistance Exercise.

We compared the immediate response and recovery of femoral cartilage morphology following aerobic or resistance exercise to a control condition. Fifteen healthy young males (23.9 years; 170.1 cm; 69.7 kg) visited the laboratory three separate days and randomly performed one of the 30-min exercise aerobic exercises (treadmill running), resistance exercises (leg presses, back squats, and knee extensions), or seated rest as the control, each followed by the 50-min recovery. Ultrasonographic images of the femoral cartilage cross-sectional area (CSA) were obtained before and after exercise and every 5 min thereafter. To test exercise effects over time, a mixed model analysis of variance and Tukey-Kramer post-hoc tests were performed (<0.05). The femoral cartilage CSA was different (condition×time: F=4.30, <0.0001) and the femoral cartilage CSA was decreased after the aerobic (-5.8%, <0.0001) and the resistance (-3.4%, =0.04) exercises compared to the re-exercise levels. Deformed femoral cartilage CSA took 35 and 10 min to return to the pre-exercise levels after aerobic and resistance exercises (+>+0.09), respectively. Thirty minutes of moderate exertion performing aerobic or resistance exercises immediately reduced the femoral cartilage CSA. A rest period ranging from 10 to 35 min was required for cartilage recovery after weight-bearing exercises.