Training with weights produces muscle soreness. Many people don’t like to be sore, and that’s why they won’t train for strength. Running also makes you sore, but not as bad and not all over the body, like weights, so running is more popular. Other people have noticed that riding a bike doesn’t produce sore muscles, so they ride a bike for exercise instead of lifting weights or running. But to some people — and this may come as a surprise to most of you — getting sore becomes the whole point of exercise. They wear their soreness like a badge of honor, and regard sore muscles as the price they must pay for continued self-improvement.
I don’t regard it as a badge of anything, but I do get them. Ibuprofen generally fixes me right up.
It also means that exercises without a significant eccentric component, like riding a bike or pushing a weighted sled, don’t make you sore. Cyclists very seldom experience sore quads even as their legs get stronger from the work of riding up hills. But this same cyclist with strong legs will experience horrible debilitating soreness if you have him squat, because he is not adapted to the eccentric component of the work. He hasn’t lowered any weight as he climbed his hills, so the squat will murder him the first time he does it.
Sure as hell murdered me. Three sets of 5 squats with 60 pounds just about crippled me for three days.