Training has an array of effects on fast and slow twitch muscle fibres which are specific to the type of training. Some of these adaptations are similar, such as: increased capillary density, which increases the delivery of blood to the muscle cells. An increase in mitochondria in the muscle cell, which increases ATP production from eh aerobic energy system. As well as increased myoglobin, which transports oxygen from the blood through the muscle to the mitochondria. However, other adaptations are specific to the muscle type.
Fast twitch muscle fibres are the fibres used for strength, power, and movements of high intensity and short duration. They can be linked with the two anaerobic energy systems, which means the adaptations in these fibres help in the use of these systems. Adaptations include increased anaerobic enzymes for glycolysis, increased PC stores, hypertrophy and increased removal of lactate, which helps reduce the acidic levels in the muscle.
Slow twitch muscle fibres are used for movements that have a long duration. They are red in colour because of the extra blood supply they have in order to assist the aerobic energy system. The adaptations within these muscles assist in the use of the aerobic energy system and include increased: mitochondria, capillary density, aerobic enzymes needed for ATP production in the aerobic energy system, glycogen and fat stores, and myoglobin. All of these adaptations help in the delivery of ATP through the aerobic energy system.