Predictive Factors of Changes in Serum Irisin Concentration after Different Exercise

This study compared serum irisin concentration changes following 16 weeks of different exercise protocols (Hill, Running, Cycling, Combined) versus Control in 289 previously sedentary adults. We identified phenotypic and genetic predictors to establish an irisin response prediction model for precise exercise prescription. Phenotypic measures (serum irisin, VO₂max, lipids) and FNDC5 SNP (rs16835198) genotyping were performed pre/post-intervention. Serum irisin significantly increased post-exercise overall (p <0.05), but with substantial interindividual variability (Δ range: -4.98 to 20.77 ng/ml; 28.03% responders, Cohen’s d ≥0.2). Under the specific (and unstandardized) exercise volumes utilized in this study, Hill and Combined training elicited the most significant increases (p<0.01). Cohen’s d-based irisin change effect size (ES) significantly correlated with baseline VO₂max (r=0.164, p<0.01) and irisin level (r=0.481, p<0.05). It was also linked to FNDC5 rs16835198 (p=0.041), with TT genotype exhibiting greater responses than GT/GG. A model incorporating baseline serum irisin concentration (β=0.522), VO₂max (β=0.107), exercise protocol (β=0.207), and rs16835198 genotype (β=0.116) explained 27.1% of the variance in the ES of Δirisin . In short, exercise-induced irisin elevation exhibits marked individual variability. Baseline irisin, VO₂max, FNDC5 rs16835198 genotype, and exercise protocol are significant predictors, accounting for 27.1% of the individual differences in training response, informing precision exercise prescriptio