The Effects of Exercise and Dietary Protein Supplementation on Muscle Mass, Muscle Function, and Appetite in Elderly Individuals

Sarcopenia is a disease characterized by the progressive weakening of skeletal muscles. The term ‘sarcopenia’ comes from the Greek ‘poverty of flesh’ and describes the characteristic loss of muscle mass and strength that corresponds with aging in otherwise healthy humans (Roubenoff & Hughes, 2000). There are numerous health risks and lifestyle consequences from this condition and thus, studies have attempted to determine ways of preventing, slowing, or reversing the development of sarcopenia. Most studies focus on the supplementation of whey protein combined or not with resistance exercise. More recently, some studies have investigated the possibility of plant-based protein as an alternative avenue for increasing protein intake in the elderly, though the majority of them have only considered soy protein as a source and have not evaluated the interventions’ effects on appetite (Stoodley et al., 2023). This study aimed to analyze whether a plant-based nutrition supplement, exercise, or a combination of the two improved markers of sarcopenia and appetite in community-dwelling older adults. This was a randomized controlled trial at the University of Padua (Unipd) in conjunction with the University College Dublin (UCD) and Friedrich–Alexander University (FAU) investigating the effectiveness of certain interventions in mitigating sarcopenia. In this study, we observed how an intervention based on exercise, a plant-based protein supplement, or the two combined, affected muscle volume, muscle function, and appetite over the course of three months (12 weeks), compared to a control group. At the Padua site, there were N = 42 total participants who were measured both at baseline and post-intervention for sarcopenic measures (N = 40 for probe day and N = 39 for food diaries). The groups were randomized and stratified by gender, with 12 subjects in the Physical Activity (PA) group, 9 in the Personalized Nutrition (PN) group, 9 in the combined PN + PA group, and 12 control participants. The PA group attended a 45-minute group exercise class twice a week for 12 weeks, while the PN group consumed Plant Protein Fiber (PPF) supplements (20g of protein and 5g of fiber) twice a day for 12 weeks. The PN + PA group followed both the PN and PA protocols for the 12 weeks. We used tools such as Dual-Energy X-ray Absorptiometry (DXA), ultrasonography (US), and maximum voluntary isometric contraction (MVIC) of the knee extensors, among others, as well as test-center provided meals and 3-day food diaries of subjects to explore whether the intervention groups had significant improvements in muscle mass, muscle function, and/or appetite. Preliminary results and data analysis from the Padua sub-group show that lean mass increased overall from baseline to post-intervention. Analysis of muscle function revealed that MVIC significantly improved at the end of the study in groups with the exercise intervention, whereas handgrip strength did not. The PPF packets proved effective at increasing protein and fiber intake, though without a clear stimulative effect on overall appetite. This thesis focuses on the experiment and results from the sub-group in Padua and its relevance to the field of Food and Health.