Williamson D L, Godard M P, Porter D A, Costill D L, Trappe S W
Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA.
J Appl Physiol (1985). 2000 Feb;88(2):627-33. doi: 10.1152/jappl.2000.88.2.627.
The purpose of this study was to examine myosin heavy chain (MHC) and myosin light chain (MLC) isoforms following 12 wk of progressive resistance training (PRT). A needle biopsy was taken from the vastus lateralis to determine fiber-type expression [ATPase (pH 4.54) and MHC/MLC] in seven healthy men (age = 74.0 +/- 1.8 yr). Subjects were also tested for 1-repetition maximum (1-RM), pre- and posttraining. The progressive knee extensor protocol consisted of three sets at 80% of 1-RM 3 days/wk for 12 wk. Freeze-dried, single muscle fibers were dissected for MHC and MLC analysis and then subjected to SDS-PAGE and silver staining, pre- and posttraining. MHC expression increased in the I (10.4%; P < 0.05) and decreased in I/IIa (9.0%; P < 0.05), I/IIa/x (0.9%; P < 0.05), and IIa/x (8.9%; P < 0.05) isoforms, with no change in the IIa and IIx isoforms, pre- vs. posttraining (total fibers = 3,059). The MLC(3f)-to-MLC(2) ratio did not change with the PRT in either the MHC I or MHC IIa isoforms (total fibers = 902), pre- to posttraining. ATPase fiber distribution did not significantly differ following training (I: 50. 4 +/- 6.7 vs. 51.9 +/- 7.9, IIa: 36.8 +/- 5.3 vs. 41.1 +/- 7.0, IIb: 12.8 +/- 5.6 vs. 7.0 +/- 4.0%; pre- vs. posttraining, respectively). 1-RM increased (51.9%; P < 0.05) from pre- to posttraining. The PRT provide a stimulus for alterations in MHC isoforms, which demonstrated a decrease in all hybrid isoforms and an increase in MHC I expression (not found in the ATPase results), unlike the MLC ratio (3:2), which was not altered with training.
本研究的目的是在进行12周渐进性抗阻训练（PRT）后，检测肌球蛋白重链（MHC）和肌球蛋白轻链（MLC）亚型。对7名健康男性（年龄 = 74.0±1.8岁）的股外侧肌进行针吸活检，以确定纤维类型表达[ATP酶（pH 4.54）和MHC/MLC]。在训练前后，还对受试者进行了1次重复最大值（1-RM）测试。渐进性伸膝方案包括以1-RM的80%进行三组训练，每周3天，共12周。训练前后，将冻干的单根肌纤维解剖用于MHC和MLC分析，然后进行SDS-PAGE和银染。训练前后，I型MHC表达增加（10.4%；P<0.05），I/IIa型（9.0%；P<0.05）、I/IIa/x型（0.9%；P<0.05）和IIa/x型（8.9%；P<0.05）MHC表达减少，IIa型和IIx型MHC表达无变化（总纤维数 = 3059）。在MHC I型或MHC IIa型中，MLC(3f)与MLC(2)的比值在训练前后均未因PRT而改变（总纤维数 = 902）。训练后，ATP酶纤维分布无显著差异（I型：50.4±6.7%对51.9±7.9%，IIa型：36.8±5.3%对41.1±7.0%，IIb型：12.8±5.6%对7.0±4.0%；分别为训练前与训练后）。1-RM从训练前到训练后增加了（51.9%；P<0.05）。PRT为MHC亚型的改变提供了刺激，与MLC比值（3:2）不同，MLC比值未因训练而改变，MHC亚型变化表现为所有杂交亚型减少，MHC I表达增加（ATP酶结果中未发现）。
