Inactivity, age, and exercise: single-muscle fiber power generation.
Inactivity, age, and exercise: single-muscle fiber power generation.
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不活动、年龄和运动：单肌纤维发电。
DOI：
10.1152/japplphysiol.00525.2012
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Thompson,LadoraV
中科院分区：
文献类型：
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作者：
Kim,Jong-Hee;Thompson,LadoraV
我们研究了温和的治疗性运动在一段时间的不活动的大小和收缩功能的肌球蛋白重链（MHC）I型（n= 204）和II型（n= 419）单纤维从内侧腓肠肌在三个年龄组。将年轻成年（5-12个月）、中年（24-31个月）和老年（32-37个月）F344 BNF 1大鼠分配到三个组中的一个：负重对照组、非负重组（NWB）和NWB加运动组（NWBX）。在NWB大鼠中应用后肢悬吊14天。NWBX大鼠在NWB期间进行15 min跑台运动，每天4次。NWBX没有提高峰值功率，但增加了正常功率的MHC I型纤维在年轻的成年大鼠。在MHC II型纤维，NWBX没有改变峰值功率，等距最大力量，Vmax，和纤维大小从年轻的成年和中年大鼠。NWBX不能改善老年大鼠的峰值功率和等长最大力量，并且显示Vmax和标准化功率的显著下降。总的来说，在不活动期间进行轻度跑步机运动并不能提高年轻、中年和老年大鼠腓肠肌MHC I型或II型纤维的峰值功率。然而，NWBX是有益的，在提高正常功率的MHC I型纤维在年轻的成年大鼠，最有可能是由于刺激强度和能力的个别纤维，以适应刺激。相反，几个因素，如受损的适应潜力，不适当的运动强度，或增加对肌肉损伤的敏感性，可能会导致缺乏改善老年大鼠。
We examined the effects of mild therapeutic exercise during a period of inactivity on size and contractile functions of myosin heavy chain (MHC) type I (n= 204) and type II (n= 419) single fibers from the medial gastrocnemius in three age groups. Young adult (5–12 mo), middle-aged (24–31 mo), and old (32–37 mo) F344BNF1 rats were assigned to one of three groups: weight-bearing control, non-weight bearing (NWB), and NWB plus exercise (NWBX). Fourteen days of hindlimb suspension were applied in NWB rats. The NWBX rats exercised on the treadmill for 15 min, four times a day, during the period of NWB. The NWBX did not improve peak power, but increased normalized power of MHC type I fibers in young adult rats. In MHC type II fibers, NWBX did not change peak power, isometric maximal force,Vmax, and fiber size from young adult and middle-aged rats. NWBX did not improve peak power and isometric maximal force and showed a dramatic decline inVmaxand normalized power in the old rats. Collectively, mild treadmill exercise during a period of inactivity does not improve peak power of MHC type I or type II fiber from the gastrocnemius in young, middle-aged, and old rats. However, NWBX is beneficial in enhancing normalized power of MHC type I fibers in young adult rats, most likely due to the stimulus intensity and the ability of the individual fibers to adapt to the stimulus. In contrast, several factors, such as impaired adaptation potential, inappropriate exercise intensity, or increased susceptibility to muscle damage, may contribute to the lack of improvement in the older rats.