The effects of additional protein intake on muscle strength and physical performance in physically active elderly

INTERVENTION: Protein supplements will be provided as ready‐to‐drink products of 250 ml containing 15 gram protein (MPC‐80) and will be produced by FrieslandCampina. De placebo supplements will be provided as ready‐to‐drink products of 250 ml and will be produced by FrieslandCampina. The products will be vanilla flavoured. Caloric content is very similar between the products. The products will be consumed twice a day for 13 weeks. CONDITION: Fragility, Sarcopenia, Muscle mass, Loss of strength ; ; PRIMARY OUTCOME: Change in maximal voluntary contraction (3 repeated measures (RM) leg extension strength test) and physical performance (SPPB) will be our primary outcome measures. SECONDARY OUTCOME: Secondary study parameters are changes in: ; ; o Muscle contractile function* ; ; o Handgrip strength and microFET (dynamometer) ; ; o Timed up‐and‐go (TUG) ; ; o Anthropometrics ; ; o Body composition (DEXA) ; ; *Performed in a subgroup of 60 subjects (30 intervention, 30 placebo) ; ; Other parameters are: ; ; o Physical fitness (Åstrand‐Rhyming test) ; ; o Physical activity (SQUASH) and exercise training (diary) ; ; o Daily dietary and protein intake (two 24h‐recalls + FFQ) ; ; o Compliance (protein supplementation) ; ; o Blood analyses ; ; o Urine analyses ; ; o Medical history questionnaire ; ; o Questionnaire screening sarcopenia (SARC‐F) ; ; o Questionnaire quality of life (EQ5D) ; ; o Questionnaires muscle complaints (Short‐Form McGill Pain Questionnaire (SF‐MPQ) and Short‐Form Brief Pain Inventory (BPI‐SF)) INCLUSION CRITERIA: ‐ 65 years or older ‐ Registered for the Nijmegen Four Days Marches 2017 ‐ Protein intake less than 1.0 g/kg bw/d based on FFQ ‐ Able to understand and perform the study procedures