The use of weighted bats is based on the theory of complex training where sets of heavier and lighter resistances are alternated to increase muscle performance.

However, other studies have found that removing portions of these series-elastic components (by way of tendon length reduction) had little effect on muscle performance.

By increasing the number of motor units recruited this training increases muscle performance.

Long-term creatine intake is beneficial to muscle performance during resistance training (abstract).

Creatine supplementation in chronic heart failure increases skeletal muscle creatine phosphate and muscle performance.

Creatine is a natural substance found in meat and fish which enhances muscle performance and growth.

"The positive health benefits of increased muscle mass among older adults extend well beyond muscle performance," they write.

"Our findings suggest that the protein-carbohydrate mix enhanced muscle performance and recovery in the later rides," said Dr. Saunders of James Madison, the study's lead author.

Observation directly improves muscle performance via mirror neurons.

Changes in muscle performance can be broadly described as the Upper Motor Neuron Syndrome.