Fig. 7.

Intermittent exercise significantly improved some dystrophic muscle metrics, without affecting animal longevity. (A) Dystrophic animals that swam only 90 min daily displayed a modest decrease in velocity over time. Continuously swimming animals had a significant drop in swimming velocity. (B) The amplitude of calcium transients in dystrophic animals increased significantly over time. (C) Worms that burrowed for 90 min daily had the greatest velocity after one exercise session (day 1). However, this effect disappeared over time. (D) Animals that burrowed continuously showed a decline in the amplitude of cytosolic calcium transients during locomotion, while animals that burrowed intermittently had a significant increase in these transients. (E) Worms that had burrowed continuously for 5 d (ii) showed signs of degeneration (arrowheads) as well as actin buildup (arrows). Intermittent-burrowing animals displayed these signs to a lesser extent. (F) After 5 d, animals that had burrowed intermittently showed increased cell area compared with animals that crawled continuously in both dys-1 and WT strains. (G) The combined muscle area of all muscle cells in a quadrant in intermittently burrowing animals was greater than that of continuously crawling animals (WT and dystrophic animals). WT animals had a greater myofibril cross-sectional area than crawling controls. However, intermittently burrowing dystrophic worms showed a decrease in myofibril cross-sectional area. (H) Animals that burrowed intermittently showed no improvement in longevity. **P < 0.001, *P < 0.05.