Extended Data Fig. 4: Long-term adaptations in the mouse model of endurance exercise.
Mice were subjected to 13 weeks of training with treadmill running (TR) or a mock (control) paradigm. The average weekly (a) body weight, and (b) workload per training session, as well as (c) the number of times the rear of the animal was touched during each training session. Individual data points are displayed with hollow symbols and the weekly means for each group are displayed with solid symbols. n = 10 per group for a-c. d-r, After 13 weeks of training, the mice were subjected to measurements of (d) grip strength, and (e) tibia length (TL). The mass of the (f) individual epididymal (Epi.) fat pads, (g) interscapular brown adipose tissue (iBAT), (h) adrenal glands, and (i) heart were measured and normalized to TL. j, The mass of individual muscles (MM) including the gastrocnemius (GAST), plantaris (PLT), soleus (SOL), flexor digitorum longus (FDL), pectoralis major (PEC), triceps brachii lateral head (Tri-Lat), triceps brachii long head (Tri-Long), and the forearm flexor complex (FF) were all normalized to TL and expressed relative to the mean value observed in the control group. k, Mid-belly cross-sections of the FDL muscles were subjected to immunohistochemistry (IHC) for laminin and fiber type identification (that is, Type I, IIA, IIX, or IIB), scale bars = 500 µm. The entire cross-section was used to determine (l), the average cross-sectional area (CSA) of the different fiber types, and (m) the proportion of the fibers that were represented by each fiber type. n, Mid-belly cross-sections of the FDL muscles were subjected to IHC for laminin and CD31 to identify capillaries, scale bars = 25 µm. o, The entire cross-section was used to determine the average number of capillaries per fiber. p-r, FDL muscles were subjected to western blot analysis for (q) members of the five OXPHOS complexes (that is, CI–CV), and (r) other mitochondrial (mito.) proteins. For each sample, the individual protein content was normalized to the total amount of protein loaded on the gel and then expressed relative to the mean of the control group. Values in the graphs are presented as the group mean ± SEM, for d-r the number of samples per group is indicated at the bottom of the bars in the graphs. The data were analyzed with two-way repeated measures (RM) ANOVA (a), one-way RM ANOVA (b,c), paired t-tests (d-i, and o), or two-way ANOVA (j, l, m, q, r). ■ Significantly different from week 1, P < 0.05. The specific P-values for all other statistically significant pairwise comparisons are annotated in the graphs.
