What causes DOMS?

Although the exact mechanism of DOMS hasn’t been determined, DOMS tends to occur after eccentric (muscle-lengthening) or novel exercises. Other factors, such as muscle damage, neutrophil accumulation, oxidative stress, inflammatory compounds (histamine, bradykinins, and prostaglandins), and fluid accumulation may also contribute to the symptoms of DOMS.^[1] However, if a person performs an exercise that causes DOMS, they may feel less sore when they perform the same exercise during future workouts; this is known as the repeated bout effect.^[2]