Spectrum of aerobic endurance running performance in eleven inbred strains of rats

The goal of this study was to identifyinbred rat strains that could serve as useful models for exploration ofthe genetic basis of aerobic endurance performance. Six rats of eachgender from 11 different inbred strains were tested for1) maximal running capacity on atreadmill and 2) isolated cardiacperformance. Running performance was estimated from1) duration of the run,2) distance run, and3) vertical work performed. Cardiacoutput, during constant preload and afterload, was taken as a measureof cardiac performance from an isolated working heart preparation. TheCOP rats were the lowest performers and the DA rats were the bestperformers by all estimates of running performance. Across the 11 strains, the distance run correlated positively with isolated cardiacperformance (r = 0.87). Estimates ofperformance were as follows (COP vs. DA strain, respectively): durationof run, 19.9 ± 1.8 vs. 41.5 ± 2.2 min; distance run, 298 ± 30 vs. 840 ± 64 m; vertical work, 15 ± 1.7 vs. 40 ± 4.4 kg/m. These ~2.5-fold differences in running performancebetween the COP and DA suggest that these strains could serve as modelsfor evaluation of the genetic basis of variance in aerobicperformance.