904Physical fitness across the life-course and the metabolic syndrome in mid-adulthood

Background Low physical fitness, including muscular strength and cardiorespiratory fitness (CRF), is a risk factor for the metabolic syndrome (MetS). However, it is unknown how physical fitness at different life stages contributes to the development of MetS. Methods Included were 783 Childhood Determinants of Adult Health Study participants who between 1985 and 2019 had measures of physical fitness (muscular strength: dominant grip strength; CRF: 1.6km run or physical work capacity at 170 beats per minute) at three life stages (childhood=7–15 years, young-adulthood=26–36 years, mid-adulthood=36–49 years) and had their MetS status assessed using the harmonised definition in mid-adulthood. The Bayesian relevant life-course exposure model, a novel statistical analytic technique, quantified associations between physical fitness at each life stage with MetS and estimated the maximum accumulated effect of physical fitness across the life-course. Results The contribution of muscular strength at each life stage with MetS in mid-adulthood was equal (childhood=36%, young-adulthood=31%, mid-adulthood=33%), whereas for CRF the greatest contribution was from childhood and mid-adulthood (childhood=41%, young-adulthood=20%, mid-adulthood=39%). A one standard deviation increase in cumulative physical fitness across the life-course was associated with 36–55% reduced odds of MetS (muscular strength: OR = 0.64, 95%Credible Interval=0.40,0.95; CRF: OR = 0.45, 95%Credible Interval=0.30,0.64). Conclusions As physical fitness at each life stage was associated with MetS in mid-adulthood, strategies aimed at increasing both childhood and adult physical fitness levels could improve future health. Key messages Increased participation in both aerobic and muscle-strengthening activities, beginning in childhood and extending into adulthood, could be encouraged to help prevent MetS.