Exercise-induced inflammatory and metabolic adaptations in ageing: A meta-analytic compendium

BACKGROUND: The relationship between metabolic and inflammatory adaptations with exercise training is poorly quantified. We employed a novel meta-analytical approach to provide an evidence-based framework to guide exercise prescription for health in older adults. METHODS: max. Our novel analytical approach divided studies into "improved" or "not improved" for each variable based on the significant direction of their standardised mean difference (95 % CI), followed by a cross-over subgroup analysis. RESULTS: Meta-analyses showed that exercise training improved all outcomes, except for IL-1β. Aerobic training showed the greatest overall benefits-except for IGF-1-while resistance training improved most markers but did not reduce body mass and IL-6. A frequency of at least 3 sessions per week was necessary to reduce body mass, insulin, HOMA-IR, triglycerides, total cholesterol, IL-6, TNF-α, leptin, and to increase adiponectin and IGF-1. Shorter interventions (< 12 weeks) led to greater increases in adiponectin and IGF-1 and stronger reductions in TNF-α and IL-1β, suggesting a transient response. Women, unhealthy individuals, and those who were overweight or obese exhibited greater improvements than their counterparts. Anti-inflammatory effects were more pronounced when accompanied by decreases in body mass, fat mass, and improved glucose and lipid metabolism, but was not dependent on those changes. CONCLUSION: Aerobic training is the most effective intervention, followed by resistance training, and at least 3 sessions per week (or twice a week for more than 24 weeks) are needed for metabolic and anti-inflammatory adaptations. This compendium provides a reference point for personalised exercise plans for treatment and prevention of chronic diseases-especially for older adults with metabolic conditions.