(a) Schematic showing isochronic pairings using blood exchange. Young C57BL/6J mice were exchanged with blood of young C57BL/6J mice either treated with vehicle (YY+Veh) or ABT263 (YY+ABT). (b) Fold change in gene expression of senescence and SASP markers, determined by RT–PCR, in skeletal muscle (gastrocnemius), kidney and liver of YY+ABT animals compared with YY+Veh 14 days after blood exchange. (c) Maximal twitch force generated by skeletal muscles, time to maximal rate of contraction and relaxation. (d) Skeletal muscle fatigue assessment. (e) Treadmill running distance in meters of YY+Veh and YY+ABT. Data are means ± s.e.m. of biologically independent samples and each data point represents an individual mouse. Data are collective of one independent experiment. n = 3 for each group in this experiment. Statistical significance was calculated using two-way ANOVA followed by two-stage step-up method of Benjamini, Krieger and Yekutieli, FDR < 0.05 (b) and two-tailed t-test with Welch’s correction (c, e), *P < 0.05. Rel, relative.