What Happens If You Miss a Workout?
Did you miss a workout? It's OK. Taking a rest day is actually highly recommended and essential for your recovery and muscle building!
Detraining Timeline
3 days: You probably won't notice any outward effects, but your body will start to make changes internally. "The body recognizes that it needs to mediate the loss of muscle fibers and begins to make changes to preserve the muscle. You won't notice much, and you won't gain fat as long as your diet doesn't drastically change."
10 days: "The muscle physiology changes and the physiological pathways that lead to muscle atrophy begin." Translation: you start to lose tone.
2 weeks: This is the point where you start to lose muscle mass, but don't worry — you won't lose strength. If you're used to using eight- to 10-pound weights at the gym, you should be able to get back in there and resume as if you'd never been gone. "Power athletes [think HIIT, cardio, running] will retain their strength, while strength athletes [think bodybuilders] will see losses at this time." You shouldn't see a major shift in weight, though, as she told us "there are no changes in body mass or body-fat percentage."
3 weeks: Liz described a "significant reduction in anaerobic power performance during activities like sprinting or HIIT."
4 weeks: At this point, you're going to notice that you might be a little out of breath when you get back to the gym. Technically speaking, this includes "up to a 10-percent decrease in max force production of muscle (1RM)" and the beginnings of "a decrease in VO2max (aerobic capacity)."