If fewer than 36 hours have passed since said workout, you need to be careful because the fibers haven't had enough time to repair, says Christine Simmons, Tier 3+ trainer at Equinox Sports Club New York. As a warm-up, foam roll sore muscle groups for five minutes each, then do 10 minutes of dynamic drills. These practices will reduce mid-exercise discomfort and speed up what’s left of the healing process.
During your workout, avoid training your aching muscles. If you do, you should at least move in a different plane. For example, your session the day after a long run would ideally be an upper-body circuit, but you could do a lower-body routine consisting of lateral and rotational exercises.
When you’re sore from a session you logged more than 36 hours ago, there’s no harm in working the aching muscles, Simmons notes. Complete the above warm-up and proceed as usual.
The bottom line:
If your soreness doesn’t ease throughout your warm-up—and especially if it gets worse—take a rest day, Simmons says.