Table 4. Quantitative analysis of fiber type distribution, CSA, SDH activity, and GPD activity in mouse muscles.
| Fiber Type | |||||||||
| Mouse Muscle | Fiber Count | Type I | Type I/IIA | Type IIA | Type IIAX | Type IIX | Type IIXB | Type IIB | |
| Red | Population (%) | 681±63 | 7.9±0.5 | 0.2±0.1 | 41.6±1.3 | 5.0±0.4 | 19.6±2.1 | 3.6±0.4 | 22.2±1.1 |
| Gastrocnemius | CSA (µm2) | 368±43 | 1743.4±28.2 | 1300.6±21.0 | 1346.2±22.8 | 1439.1±24.7 | 2002.2±32.2 | 2476.8±39.9 | 2846.8±47.7 |
| (RG) | SDH (AU) | 368±43 | 1.146±0.061 | 1.431±0.032 | 1.894±0.040 | 1.656±0.066 | 1.332±0.101 | 1.010±0.056 | 0.608±0.044 |
| GPD (AU) | 368±43 | 1.237±0.065 | 1.791±0.176 | 2.336±0.146 | 3.225±0.193 | 3.818±0.241 | 4.265±0.178 | 4.831±0.181 | |
| Mixed | Population (%) | 576±68 | 0 | 0 | 20.9±1.6 | 3.6±0.4 | 14.8±1.1 | 4.9±0.8 | 55.7±1.4 |
| Gastrocnemius | CSA (µm2) | 268±69 | - | - | 1088.2±32.2 | 1195.2±42.3 | 1554.4±84.9 | 2281.8±70.8 | 2640.3±85.6 |
| (MG) | SDH (AU) | 268±69 | - | - | 1.855±0.079 | 1.744±0.083 | 1.394±0.066 | 1.023±0.048 | 0.443±0.017 |
| GPD (AU) | 268±69 | - | - | 2.454±0.097 | 3.304±0.058 | 4.143±0.180 | 4.822±0.152 | 5.218±0.192 | |
| White | Population (%) | 669±101 | 0 | 0 | 0 | 0 | 1.6±0.6 | 1.5±0.4 | 97.0±0.8 |
| Gastrocnemius | CSA (µm2) | 277±43 | - | - | - | - | 1240.7±20.0 | 1692.9±27.3 | 2639.2±49.3 |
| (WG) | SDH (AU) | 277±43 | - | - | - | - | 1.030±0.064 | 0.684±0.058 | 0.324±0.033 |
| GPD (AU) | 277±43 | - | - | - | - | 3.362±0.198 | 3.672±0.220 | 4.156±0.195 | |
| Soleus | Population (%) | 622±60 | 30.6±2.2 | 0.6±0.2 | 49.1±1.2 | 4.4±0.7 | 11.8±1.7 | 0.5±0.1 | 3.1±1.1 |
| (Sol) | CSA (µm2) | 259±28 | 1560.8±25.6 | 1332.8±20.3 | 1356.4±23.6 | 1550.6±53.7 | 1686.0±32.9 | 1916.4±25.1 | 2266.6±33.5 |
| SDH (AU) | 259±28 | 1.000±0.058 | 1.406±0.143 | 1.535±0.083 | 1.436±0.051 | 1.170±0.053 | 0.928±0.014 | 0.576±0.010 | |
| GPD (AU) | 259±28 | 1.000±0.099 | 1.506±0.024 | 1.885±0.067 | 3.305±0.118 | 3.666±0.179 | 4.739±0.079 | 5.231±0.100 | |
| Plantaris | Population (%) | 730±48 | 0 | 0 | 19.4±1.4 | 8.3±0.8 | 22.4±2.3 | 3.0±0.6 | 46.9±2.4 |
| (Pla) | CSA (µm2) | 362±38 | - | - | 1073.2±109.9 | 1222.3±107.1 | 1775.7±135.1 | 2308.0±124.6 | 2619.7±106.4 |
| SDH (AU) | 362±38 | - | - | 1.599±0.091 | 1.381±0.083 | 1.048±0.068 | 0.720±0.066 | 0.443±0.026 | |
| GPD (AU) | 362±38 | - | - | 1.511±0.061 | 2.273±0.078 | 2.950±0.155 | 3.456±0.335 | 3.900±0.347 | |
| Extensor | Population (%) | 758±59 | 0 | 0 | 10.2±0.9 | 3.6±0.5 | 23.7±0.9 | 6.8±0.6 | 55.7±1.2 |
| Digitorum | CSA (µm2) | 307±35 | - | - | 517.3±11.7 | 528.2±5.6 | 953.9±53.2 | 1270.9±52.1 | 2108.4±52.1 |
| Longus (EDL) | SDH (AU) | 307±35 | - | - | 1.495±0.124 | 1.384±0.089 | 1.027±0.054 | 0.775±0.056 | 0.356±0.022 |
| GPD (AU) | 307±35 | - | - | 2.164±0.154 | 2.889±0.195 | 3.421±0.229 | 3.694±0.195 | 4.055±0.295 | |
| Red Tibialis | Population (%) | 857±50 | 0.6±0.6 | 0 | 18.2±2.4 | 8.3±0.5 | 44.7±1.9 | 3.0±0.5 | 25.1±1.6 |
| Anterior (RTA) | CSA (µm2) | 368±51 | 1501.4±7.1 | - | 1369.6±22.4 | 1665.0±26.8 | 2186.0±35.2 | 2610.6±53.1 | 3073.8±51.3 |
| SDH (AU) | 368±51 | 0.948±0.002 | - | 1.773±0.006 | 1.587±0.057 | 1.211±0.041 | 0.685±0.015 | 0.444±0.026 | |
| GPD (AU) | 368±51 | 1.821±0.007 | - | 3.122±0.133 | 4.015±0.144 | 4.694±0.165 | 5.161±0.209 | 5.568±0.202 | |
| White Tibialis | Population (%) | 600±59 | 0 | 0 | 0.6±0.3 | 4.4±0.5 | 16.3±1.7 | 7.7±1.2 | 70.9±1.8 |
| Anterior (WTA) | CSA (µm2) | 249±17 | - | - | 735.7±31.2 | 998.4±46.3 | 1415.8±23.4 | 2166.4±36.2 | 3010.1±51.6 |
| SDH (AU) | 249±17 | - | - | 1.094±0.144 | 0.949±0.083 | 0.574±0.123 | 0.429±0.156 | 0.209±0.056 | |
| GPD (AU) | 249±17 | - | - | 3.394±0.192 | 4.189±0.155 | 4.362±0.054 | 4.897±0.107 | 4.995±0.094 | |
| Vastus | Population (%) | 703±54 | 2.4±0.5 | 0.3±0.2 | 37.6±3.2 | 9.4±0.6 | 24.7±1.3 | 2.1±0.5 | 23.5±2.5 |
| Intermedius (VI) | CSA (µm2) | 332±37 | 2579.3±63.4 | 2042.4±19.8 | 2087.8±29.3 | 2396.9±74.9 | 2736.2±64.6 | 2873.3±61.1 | 3732.1±102.1 |
| SDH (AU) | 332±37 | 1.059±0.042 | 1.180±0.026 | 1.613±0.052 | 1.395±0.055 | 1.188±0.013 | 0.703±0.033 | 0.415±0.038 | |
| GPD (AU) | 332±37 | 1.161±0.028 | 1.485±0.175 | 2.179±0.145 | 2.872±0.124 | 3.279±0.085 | 4.065±0.124 | 4.245±0.154 | |
| White Vastus | Population (%) | 542±78 | 0 | 0 | 0 | 0 | 1.3±0.3 | 5.4±0.7 | 93.4±0.9 |
| Lateralis (WVL) | CSA (µm2) | 218±32 | - | - | - | - | 913.0±25.5 | 1489.2±35.0 | 3489.8±92.0 |
| SDH (AU) | 218±32 | - | - | - | - | 1.069±0.124 | 0.700±0.048 | 0.252±0.018 | |
| GPD (AU) | 218±32 | - | - | - | - | 3.531±0.158 | 3.740±0.156 | 3.827±0.173 | |
SDH and GPD activity staining are expressed relative to the values obtained for mouse soleus type I fibers (assigned a reference value of 1.0). The number of fibers counted/quantified for each parameter is also given. Values are means ± SEM (n = 6 per muscle).