Low energy availability reduces myofibrillar and sarcoplasmic muscle protein synthesis in trained females

Low energy availability (LEA) describes a state where the energy intake is insufficient to cover the energy costs of both exercise energy expenditure and basal physiological body functions. 

LEA has been associated with various physiological consequences, such as reproductive dysfunction. However, the effect of LEA on skeletal muscle protein synthesis in females performing exercise training is still poorly understood. 

This study conducted a randomized controlled trial to investigate the impact of LEA on daily integrated myofibrillar and sarcoplasmic muscle protein synthesis in trained females. 

The Resting energy expenditure was determined by indirect calorimetry using a ventilated hood system (Q-NRG, COSMED, Italy).

The conclusions showed that 10 days of LEA impairs daily integrated myofibrillar and sarcoplasmic muscle protein synthesis under well-controlled laboratory conditions in trained females. Furthermore, these impairments were accompanied by reductions in lean mass, nitrogen balance, free androgen index, thyroid hormone concentrations, resting metabolic rate and increased cortisol/insulin ratio.

The findings suggest that LEA may have negative consequences for skeletal muscle adaptations and highlight the importance of ensuring adequate energy availability in female athletes.