Relationship between lactate accumulation, LDH activity, LDH isozyme and fibre type distribution in human skeletal muscle.

Lactate concentration, total LDH activity and muscle-specific LDH isozymes were determined in pools of the two main types of human skeletal muscle fibres. Analyses were made from biopsy specimens obtained after intense dynamic exercise lasting approximately 30 s. Lactate concentration, total LDH activity and muscle-specific LDH activity displayed higher average values for FT (fast twitch) fibres than for ST (slow twitch) fibres. In addition, positive correlations were found both between the individual percentage of FT fibres and muscle lactate concentration and between lactate concentration and total LDH activity and muscle-specific LDH activity respectively.