Disproportionate changes in skeletal muscle strength and size with resistance training and ageing.
The ability of a muscle to shorten and produce force is crucial for locomotion, posture, balance and respiration. During a contraction, myosin heads on the myosin filament propel the actin filament via ATP hydrolysis, resulting in shortening of the muscle and/or force generation. The maximal shortening velocity of a muscle fibre is largely determined by the myosin ATPase activity, while maximal force is primarily determined by the cross-sectional area. Since most muscles are pennate rather than parallel-fibred and work at different lever ratios, muscle architecture and joint-tendon anatomy has to be taken into account to obtain the force and velocity characteristics of a muscle. Additionally, the recruitment of agonistic and antagonistic muscles will contribute to the torque generated during a contraction. Finally, tendon compliance may impact on the rate of force rise and force generated if it is such that the muscle contraction proceeds in the ascending limb of the length-tension relation. Even when magnetic resonance imaging and ultrasound, combined with EMG and/or electrical stimulation, have been applied to relate changes in muscle contractile properties to alterations in muscle size and architecture during ageing and resistance training, a disproportionate change in muscle strength and size remains to be explained.
Degens
H
H
Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester M1 5GD, UK. h.degens@mmu.ac.uk
Erskine
R M
RM
Morse
C I
CI
D000255:Adenosine Triphosphate / Q000378:metabolism; D000375:Aging / Q000502:physiology*; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology*; D009129:Muscle Tonus / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009929:Organ Size / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D055070:Resistance Training
D000255:Adenosine Triphosphate