Assessment of muscle damage relies commonly on subjective sensation of pain. The purpose of this research was to test thevalidity of microcurrent conductance on skin over injured tissue to quantify soft tissue injury and recovery following heavy exercisecompared to other indexes of muscle soreness. A randomized, controlled, single-blinded, 1-week trial on 60 subjects.Setting-University Interventions: Subjects did 3 sets of squats for 5 min each. There were 3 groups of 20 subjects. One did nothing andone had heat applied for 8 h post exercise. The final group had heat 24 h after exercise. Tissue resistance and muscle strength force tomove the knee, analog visual pain scale. In the control group, microcurrent continually decreased, eventually decreasing 32% by thethird day post exercise. When heat was given immediately following exercise, microcurrent was 26% greater (P 〈 0.001). The painscale rose to 3.1/10 as opposed to 5.4/10 for controls. Strength and muscle elasticity stayed mostly constant after heat as opposed to a28% decrease in strength and increase in stiffness in the control subjects. For 24 h delayed heat, microcurrent was 14% greater(P 〈 0.02), and was unchanged for the first 24 h when no therapy was given. Pain scale rose to 4.8/10. Stiffness was unchanged whilemuscle strength decreased the same as controls. Microcurrent shows agreement with loss of strength, and stiffness from DOMS but notthe subjective pain measure. It appears that microcurrent is a good measure of muscle damage.