Depending on what your goals are, I disagree. If your goal is to stimulate hypertrophy, it’s not uncommon to be sore from leg training for 5+ days.

If your goal is strength, the soreness shouldn’t last quite as long. Most of the delayed onset muscle soreness you experience occurs during the eccentric portion of the movement, which is also responsible for maximal muscle growth.

But it’s the concentric motion that’s responsible for expressing strength.

For a runner, the concentric motion is far more important. If you want to do squats but reduce the duration of soreness, then I recommend barbell back squats over a box.

Put a box under your butt just above your maximal depth. Put the weight on your back and squat down to the box in one smooth motion. Actually sit on the box and take the tension off of the muscle. Stay braced and don’t leave your proper squatting form. After a 2 count, explode upward. Repeat for reps.

This will reduce the amount of time you spend in the eccentric, which will reduce soreness. It will also shift your energy expenditure from the eccentric and toward the concentric. You will achieve a higher quantity of high quality concentric contractions. Note that I did not say you would achieve more overall reps, just that more of the reps that you do will have higher quality concentric motions.

If, however, you don’t want any, or very little soreness, then don’t waste time with weights. All you really need for that are some body weight movements with one or two plyometric exercises sprinkled in.

All of that said, I do two leg sessions a week. A heavy session and a high volume session. A big part of how quickly you get rid of soreness depends on sleep and diet. You need a proper recovery meal. At least 20g of protein and 20g of simple carbs. Yes. Sugar. Preferably dextrose. An insulin spike will end muscle protein breakdown and jumpstart muscle protein synthesis.

A proper recovery meal is responsible for preventing probably half of your overall soreness, and it’s the part most people screw up without ever realizing it.