Skeletal Muscle Mitochondria in Ageing

Participants will undertake an incremental ramp test on a cycle ergometer to determine maximal oxygen uptake (V̇O2max) and the gas exchange threshold (GET). Throughout the exercise test, muscle oxygenation and deoxygenation will be monitored by NIRS.

Muscle volume and morphological characteristics will be assessed via 3D ultrasound imaging.

To determine the contractile properties of the knee extensors, participants will perform maximal isometric and isoinertial contractions of the knee extensors on a dynamometer.

Participants will perform a series of moderate-intensity constant power output exercise bouts on a cycle ergometer following which the recovery rates of muscle V̇O2 will be determined via a series of intermittent arterial occlusions. Throughout all tests, pulmonary gas exchange and ventilation will be determined and muscle oxygenation and deoxygenation will be monitored by NIRS.

Exercise will be performed on a custom-built magnetic resonance-compatible cycle ergometer in supine position for determination of muscle phosphocreatine recovery kinetics using 31phosphorous magnetic resonance spectroscopy \[31P-MRS\].

A muscle biopsy will be obtained from the vastus lateralis using a modified Bergström needle technique with suction.