High-volume aerobic training can negatively affect muscle development, while low-volume walking or HIIT sessions are unlikely to.

“So, particularly with the aerobic training, are you doing long slow distance? Are you doing six days a week of marathon running training? Yeah, that's going to certainly start to have negative effects on your muscle development. If you're walking 10,000 steps a day, 12,000 steps a day, very unlikely that's going to have any negative effect. If you're doing three high-intensity interval training sessions per week, very unlikely that's going to have a negative effects.”