Q: I’m on a split routine, working out each body part twice a week. My partner and I are trying a new exercise tempo, really emphasizing the the negative. When our second pec day came around, we were both too sore to get anything done. Do you need more rest after negatives?
Charles Staley: Muscle soreness is almost always an indicator that your muscles are still repairing themselves. After exercise, the release of an amino acid called hydroxyproline is released to repair microtrauma in the muscle fibers. Being a very toxic substance, hydroxyproline irritates the nerve endings, causing tenderness (soreness is NOT caused by lactic acid, by the way). Re-training these unrecovered muscles will only damage them more – if you repeat this pattern habitually, you may very well end up with a traumatic injury.
Eccentric training is universally accepted as being more traumatizing than concentric training. If you’ve ever taken a long hike up a mountain, camped overnight, and then hiked back down the next day, you might have noticed that you woke up feeling relatively unscathed, only to find that you got very sore the next day. This is because the hike up is primarily concentric work for your quads, and the hike down is mostly eccentric.
As a rule, wait one entire day (some of my colleagues would say two) after your soreness has disappeared before training the same muscle(s) again. Don’t worry if it seems like your training frequency seems insufficient – the vast majority of people train too often.