2.3. Skeletal muscle (SKM) function test

The test was performed at the completion of the SFN diet administration, according to the procedure described by Handschin et al. (2007). Mice were trained and allowed to run on a motorized, speed‐controlled, modular treadmill system, Exer 3/6 (Columbus Instruments, OH). The treadmill was equipped with an electric shock stimulus (set at 1 Hz, 20% output) and an adjustable inclination angle. All mice were acclimatized to the treadmill (first with the belt unmoving, followed by shock grids off but the belt motor turned on) for 15 min/day for three consecutive days followed by 10 min at 8 m/min for three consecutive days before an experiment. For the exercise tolerance test, mice were allowed to warm up at 8 m/min and 0% incline for 5 min. At every 2‐min interval, workload was augmented by alternating increases in belt speed of 2 m/min or increases in incline of 10% grade until mice developed exhaustion or a maximum speed of 46 m/min was reached. Exhaustion was defined when mice were unable to avoid repetitive electrical shocks for 5 continuous seconds. Running time until exhaustion was measured, and the running distance, work, and power were calculated. Distance is a function of time and speed of the treadmill. Work (kJ) was calculated as the product of bodyweight (kg), gravity (9.81 m/s²), vertical speed (m/s × angle), and time (s).