In resistance-trained adults, moderate-intensity, high-volume back squats and deadlifts produce equivalent levels of delayed-onset muscle soreness peaking at 24 hours post-exercise, despite differences in neuromuscular fatigue profiles, indicating that subjective muscle soreness does not reliably reflect the type or severity of neuromuscular impairment.

When muscles are worked hard with many repetitions, they build up waste chemicals that slow down their ability to contract, and the brain reduces signals to the muscles, making them weaker and slower to respond. At the same time, the muscle fibers get tiny tears from being stretched under load. These tears activate sensors in the muscle that send pain signals to the brain, causing soreness the next day. Even though the weakness and slowness from the workout are different depending on the exercise, the muscle damage and resulting soreness are the same because both exercises stretch and stress the muscles enough to cause the same level of tearing.