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Andreo Fernando AguiarMHC content and fiber-type frequency. The representative SDS-PAGE gel usedto quantify MHC isoforms is shown in Fig. 7A, and the corresponding data aresummarized in Table 3. Resistance training during 12 weeks promoted a significant (p 0.05) in the MHCIIa and MHCIIx/d content was observed in T8 group,in relation to the C8 group (Table 3). The training during 8 and 12 weeks did notpromote any significant alteration in MHCI and MHCIIb content in the T8 and T12groups, compared to the C8 and C12 groups respectively (Table 3).Table 3. Relative myosin heavy chain (MHC) isoforms percentages of plantaris musclesamples determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis.Groups MHCI MHCIIA MHCIID MHCIIBC8 6,3 ± 1,1 12,0 ± 1,0 48,2 ± 3,0 33,6 ± 1,1T8 4,7 ± 1,6 13,6 ± 2,7 47,2 ± 4,6 34,4 ± 1,6C12 4,5 ± 3,1 12,5 ± 1,4 48,1 ± 3,6 35,0 ± 3,1T12 6,1 ± 1,3 16,3 ± 0,5* 41,7 ± 2,7* 36,0 ± 1,3Values are means ± SD. n= 8 rats per group. C8, 8 weeks control; T8, 8 weeks trained;C12, 12 weeks control; and T12, 12 weeks trained. * Significant difference comparedto C12 group at p < 0.05 (ANOVA + Tukey test)The advantages of our study compared with previous work in this area includethe full range of histochemical fiber types and relative MHC content (Fig. 7A) tovalidate the histochemical data. Fiber-type frequency for each group is shown in Fig.7C,and the corresponding mATPase histochemistry used for fiber-types characterization isshown in Fig. 2 and 8A. The significant (p < 0.05) increase of MHCIIa content andreduction of MHCIIx/d in the T12 group (Table 3) reflected in a significant (p < 0.05)increase in percentages of type IIA fibers and reduction of type IIX/D fibers comparedto the C12 group (Fig. 7C). In agreement with no significant (p > 0.05) change in MHCisoforms content, the training during 8 weeks did not promote any significant (p > 0.05)alteration in the frequency of type IIA and IIX/D fibers in the T8 group compared to theC8 group (Fig. 7C). No statistical difference (p > 0.05) was observed in the frequencyof type I and IIB fibers among all groups (Fig. 7C).58