Muscle function is multi-dimensional, with different components of function such as power, balance, and fatigability relating to clinical and quality of life outcomes such as mobility, falls risk and the ability to carry out activities of daily living. Maintaining good muscle function across life is essential for overall health, mobility, and wellbeing. Previous research has largely focused on identifying factors that influence declines in muscle function in older adults. However, muscle function in later life is a consequence not only of declines experienced from midlife onwards but also of the peak achieved earlier in adulthood.

In addition, large population-based studies like ALSPAC have typically used simple measures of muscle function, which may not capture variance in important aspects including balance, power, mobility, and fatiguability.

In the recent ALSPAC@30 clinic, multiple detailed measures of different aspects of muscle function including power, balance and fatigability were ascertained, at scale, for the first time in young adults. We aim to combine these novel data with ALSPAC’s existing longitudinal information on exposures including physical activity (PA) and obesity. This provides a unique opportunity to identify and investigate important factors associated with the promotion of maximum peak muscle function.

In this project, we are particularly interested in looking at how PA, sedentary behaviour (SB) and body composition including obesity from birth onwards are associated with peak muscle function. Previous studies have shown that PA, SB, and body composition are important for muscle function in children and middle-aged and older adults, although we have limited understanding of their association with peak muscle function in young adults. We expect that the impact of these factors will be more pronounced in cohorts born from the 1990s onwards, including the ALSPAC cohort, because younger generations are much more likely to be inactive and obese than previous generations.

In addition, we can benefit from the fact that new technologies allow us to measure physical activity and obesity more accurately and in greater detail than ever before. There are several typical patterns of PA, SB and obesity change throughout childhood, adolescence and early adulthood, and so we are keen to find out if there are particular periods of development during these key life stages where differences in PA, SB or obesity have a greater influence on muscle function.