Objectives: Low muscular strength is a risk factor for current and future adverse health outcomes. However, whether levels of muscular strength persist, or track, and if there are distinct muscular strength trajectories across the life course is unclear. This study aimed to explore muscular strength trajectories between childhood and mid-adulthood.

Design: Prospective longitudinal study.

Methods: Childhood Determinants of Adult Health Study participants had their muscular strength (right and left handgrip, shoulder extension and flexion, and leg strength measured by hand-held, shoulder and leg-back dynamometers, and a combined strength score) assessed in childhood, young adulthood and mid-adulthood. The tracking of muscular strength was quantified between childhood and mid-adulthood (n = 385) and young- and mid-adulthood (n = 822). Muscular strength trajectory patterns were identified for participants who had their muscular strength assessed at least twice across the life course (n = 1280).

Results: Levels of muscular strength were persistent between childhood and mid-adulthood and between young- and mid-adulthood, with the highest tracking correlations observed for the combined strength score (childhood to mid-adulthood: r = 0.47, p < 0.001; young- to mid-adulthood: r = 0.72, p < 0.001). Three trajectories of combined muscular strength were identified across the life course; participants maintained average, above average, or below average levels of combined muscular strength.

Conclusions: Weak children are likely to become weak adults in midlife unless strategies aimed at increasing muscular strength levels are introduced. Whether interventions aimed at increasing muscular strength could be implemented in childhood to help establish favourable muscular strength trajectories across the life course and in turn, better future health, warrant further attention.