Question

What causes muscle soreness during exercise?
Buildup of lactic acid
Low blood sugar
Dehydration

Answer 1

Short answer: none of the three is the main cause of the common “muscle soreness” people feel after exercise.

Details:
- Delayed onset muscle soreness (DOMS), the ache and stiffness that peaks 24–72 hours after unaccustomed or intense exercise, is caused mainly by microscopic damage to muscle fibers and the subsequent inflammation and repair—not by lactic acid buildup.
- “Burning” pain felt during very intense exercise is related to metabolic byproducts (including H+ ions that lower pH) and fatigue; lactate (often called lactic acid) is associated with that acute burning sensation but is cleared from muscle and blood within an hour after exercise and is not responsible for DOMS.
- Low blood sugar (hypoglycemia) causes weakness, dizziness, and fatigue, not localized muscle soreness.
- Dehydration can contribute to muscle cramps and make recovery slower, but it is not the primary cause of DOMS.

Practical tips: progress training gradually, include rest and active recovery, stay hydrated, eat adequate protein and carbs for repair, and use gentle stretching, massage, or cold/heat as needed.