Gaining insight in factors associated with successful ageing: body composition, nutrition, and cognition

Frailty is defined as a geriatric condition characterized by an increased vulnerability to external stressors, leading to a loss of reserve capacity. This condition is characterized by a loss of muscle mass. Muscle ultrasound might play an important role in quantifying this loss, and therefore the validity and reliability of muscle ultrasound was investigated. Furthermore, this thesis aimed to identify methods for determining malnutrition and lastly we investigated the influence of nutrition and exercise on psychosocial frailty.
This thesis shows that muscle ultrasound is a valid and reliable method for determining muscle size. Currently, muscle ultrasound cannot be used to diagnose sarcopenia and malnutrition because in both definitions it is not muscle size, but (whole body) muscle mass that is determined. Determining muscle size is important as it provides possibilities for starting targeted interventions. For example, in the event of loss of muscle mass in the lower limbs, exercise intervention may be indicated as part of the treatment. Another recommendation from this thesis is that normative data for muscle size should be determined, in order to be included in the criteria of sarcopenia and malnutrition. This dissertation also suggests that a healthy diet plays an important role in cognitive functioning and that protein intake contributes to the maintenance of muscle mass.