Protein Intake and Exercise-induced Muscle Damage

Comparing the Effects of Three PROtein-enhancement Strategies on Exercise-induced Muscle Damage in Older Adults

The goal of this clinical trial is to test the effect of different protein-enhancement strategies versus carbohydrate control on exercise-induced muscle damage in physically active older adults. The main question it aims to answer is:

What is the effect of three different protein-enhancement strategies (whey protein (WP), mixed plant-based protein (MPP), and use of protein-rich food products (PFP) on exercise-induced muscle damage in older adults compared to isocaloric carbohydrate control?

Participants will:

• Use a protein-enhancement strategy (WP, MPP or PFP) or carbohydrate control for a total of 5 weeks;
• Participate in a single walking bound (30/40/50 km) two weeks after the start of the study;
• Participate in a consecutive walking bound (4 days of 30/40/50 km) in the last week of the study period;
• Complete different questionnaires and give blood samples to test for muscle damage.

Inclusion Criteria:

• 60 years or older
• Registered for the Nijmegen Four Days Marches (i.e., able to walk 30-50 km/day)
• A habitual protein intake <1.0 g/kg/d based on the protein 55+ (PRO55+) screening tool
• Able to understand and perform the study procedures
• Able to use a mobile device

Exclusion Criteria:

• Allergic or sensitive for milk proteins, or lactose intolerant
• Diagnosed type I or type II diabetes mellitus
• Diagnosed intestinal diseases influencing the uptake of protein (i.e., active inflammatory bowel disease, Crohn's disease)
• Consumption of other freely available protein supplements during the study period.
• If the subject intends to perform additional exercise bouts that cause muscle damage in the 4 days before the single- and multiple exercise bouts.