The aim of this study is to investigate the effect of oral ketone administration during inactivity-induced muscle atrophy and retraining-induced regeneration. Potential changes in muscle function (cycling performance, knee-extension force and power, jump height) and mass, blood flow and the muscular extracellular matrix will be the main focus. In this context, the dominant leg of the participants (n=24) will be immobilized with a brace for 2 weeks and subsequently retrained in a 4-week progressive resistance exercise training program to stimulate muscle regeneration. During the immobilization and rehabilitation period, participants receive either ketone ester (KE) or placebo (CON). 4 experimental sessions are performed during this time frame in order to evaluate the effects of the trial.

Inclusion Criteria:

• Recreational sports participation, including general fitness training, between 2 and 5 hours max per week
• Good health status confirmed by a medical screening
• Body mass index between 18 and 25

Exclusion Criteria:

• Any kind of injury/pathology that is a contra-indication to perform resistance exercise
• Intake of any medication or nutritional supplement that could impact muscle protein synthesis during the period of the study
• Intake of any whey protein, casein or branched-chain amino acid supplement or anti-inflammatory drug from 1 month prior to the start of the study
• Blood donation within 3 months prior to the start of the study
• Smoking
• Pregnant
• More than 3 alcoholic beverages per day
• Current participation in another research trial
• Any other argument to believe that the subject is unlikely to successfully complete the full study protocol
• Adherence to a high-fat, low-carbohydrate ketogenic diet (less than 20% of energy intake derived from carbohydrates)
• (Cow's) milk protein allergy