University of Illinois at Urbana-Champaign Oct 2 2025 New research offers potential good news for those who've lapsed at the gym. The study found that mice that voluntarily ran on an exercise wheel for four weeks, stopped for four weeks and ran again for another four weeks saw unexpected gains. The second bout of wheel running led to a bigger increase in the size of muscle fibers than the first, even though the retraining effort was less intense than the initial bout, researchers report. The