What does soreness actually mean?

Take-aways

1. Soreness doesn’t actually tell you about the amount of muscle damage you’re carrying, nor does it meaningfully predict performance/recovery. The timelines associated with the recovery of performance and the timelines associated with DOMS don’t overlap very well.

2. What soreness does tell you is whether you trained/elicited a muscle damage and remodelling response in a given muscle. But, with how unreliable soreness ratings are, using them to guide your training is premature and misguided.

   1. Soreness probably isn’t anything that you need to track or pay attention to in your training. Performance in the gym - whether you’re generally having consistent or improved performance week-to-week - will be a much better gauge of recovery.

   2. Soreness probably doesn’t tell you much about how effective your training is or isn’t. It mostly just tells you that you elicited a remodelling response.

There’s a growing trend in the evidence-based fitness space to use soreness as a means to individualize your training.

The idea is that soreness closely correlates to muscle damage or is overall indicative of your recovery state. Additionally, the claim is sometimes made that an exercise can be evaluated on the basis of the degree of delayed-onset-muscle-soreness (DOMS) it elicits. If an exercise causes a greater amount of soreness than another, the thinking goes, it should be the better choice in targeting that muscle group.

Is there any truth to this? Does DOMS actually give us a practical proxy for muscle damage? What does DOMS actually tell us, and should we pay close attention?

First, let’s touch on the idea that DOMS is a good proxy for muscle damage.

A study by Nosaka and colleagues tried to examine exactly this idea. First, they induced muscle damage through eccentric contractions (which induces greater muscle damage than concentric training).

They then assessed DOMS and muscle damage in a variety of ways, to see whether the two would correlate.

A variety of markers of muscle damage (Creatine Kinase, force production, range of motion, etc.) were measured in the four days following the eccentric training protocol.

Likewise, they also assessed soreness using three different methods: asking participants to rate soreness while the researchers palpated the trained muscle, and soreness rating when flexing/extending the target joint.

Well, was soreness a good predictor of muscle damage/its biomarkers?

Basically, no. Correlations were rarely significant, and, even when they were, the strength of the association ranged from 0.08-0.31. For context, r<0.3 is usually considered negligible/very weak.

Importantly, soreness didn’t even have a high correlation with itself. In other words, ratings of soreness from participants weren’t even consistent when assessed in different positions - when the arm was flexed, versus palpated, versus extended, for instance (r=0.33-0.66).

So, soreness - as you perceive it - doesn’t tell you much about muscle damage. Does it at least tell you about whether you’ve recovered from the last session? If you’re quite sore, does that mean you shouldn’t train.

Well.. probably not. While the authors did find a significant (but weak) correlation between force production and soreness, this was actually a positive correlation. That is to say, the more sore they were, the more force they were able to produce.

MIF - Maximum Isometric Force. d1 = day 1 after eccentric training, d4 = day 4 after eccentric training.

You may be surprised, but this tracks with a line of research suggesting that soreness is associated with the recovery or remodelling process rather than with high levels of muscle damage.

So, soreness also doesn’t tell you whether you should take an extra rest day or whether you’ve recovered from that last session.