Can improvements in muscle quality improve fitness levels in type 2 diabetics?

This study examined whether improved muscle quality is associated with improved fitness levels in type 2 diabetics.

Muscles in patients with type 2 diabetes (T2D) have a reduced ability to take up glucose from the blood. Patients have a high muscle mass and a reduction in muscle quality as a result. A reduction in muscle quality is associated with reduced physical function and a reduction in quality of life.

Cardiorespiratory fitness can be enhanced by regular exercise. This reduces the risk of cardiovascular disease. T2D patients that engage in regular exercise to increase muscle quality can improve their fitness levels. However it is unknown whether improvements in muscle quality are responsible for the improvements in fitness levels.

This study aimed to determine whether exercise-improved muscle quality is associated with improved fitness levels in T2D patients. This study involved 196 T2D patients divided into 4 groups. One group did not alter their daily exercise over a 9 month period. One group performed aerobic training (moderate intensity exercise). Aerobic training was carried out for 150 minutes each week for 9 months. One group performed a session of resistance training 3 days a week for 9 months. Resistance training involved upper body exercises, lower body exercises, abdominal crunches and back extensions. The remaining group performed a combination of aerobic and resistance training for 9 months. 

After 9 months, changes in muscle quality were associated with changes in cardiorespiratory fitness. Improved fitness was identified by an increased amount of oxygen used by the body and an increased time to treadmill exhaustion (time until patient is exhausted running on a treadmill). Participants had greater fitness levels when aerobic training and resistance training were combined.

This study suggests that changes in muscle quality after exercise can improve fitness levels in T2D patients. 

MRI or CT imaging would have been more appropriate to measure muscle quality. This study only showed an association between muscle quality and cardiorespiratory fitness. It did not determine whether muscle quality directly improves fitness.

Consult your physician about carrying out aerobic training and resistance training to improve fitness.