Alley K A, Thompson L V
Master of Physical Therapy Program, College of St. Catherine, Minneapolis, USA.
Arch Phys Med Rehabil. 1997 Jan;78(1):19-25. doi: 10.1016/s0003-9993(97)90004-6.
To characterize specific musculoskeletal contractile property changes that occur during inactivity and intermittent weight bearing in aged muscle.
Randomized control trial.
A controlled laboratory environment.
Fifteen aged rats were randomly assigned to control (CON), hindlimb unweighted (HU), and hindlimb unweighted with intermittent weight bearing (HU-IWB) groups.
The HU and HU-IWB rats were suspended for 1 week. The HU-IWB animals were unsuspended four times daily allowing 15 minutes of weight-bearing.
Muscle weights, muscle fiber diameter, peak absolute force, peak specific tension (P0), and maximal shortening velocity (V0).
In comparison to CON animals, the soleus (SOL) wet weight was significantly (p < or = .05) reduced by 19% and 6% in HU and HU-IWB animals, respectively. SOL single fiber analysis showed no difference in fiber diameter between the three groups. However, peak absolute force and P0 of SOL type I fibers were significantly (p < or = .05) reduced in the HU group compared to CON values. V0 of SOL fibers increased with HU. In comparison to CON animals, the gastrocnemius (GAS) wet weight was significantly reduced by 9% and 8% in HU and HU-IWB animals, respectively.
Inactivity significantly altered the contractile properties of single fibers isolated from aged mammalian SOL skeletal muscle. Furthermore, minimal weight bearing attenuated these detrimental effects induced by inactivity in the SOL. However, this weight-bearing protocol did not attenuate the inactivity-induced alterations in aged mammalian GAS skeletal muscle.
描述老年肌肉在不活动和间歇性负重期间发生的特定肌肉骨骼收缩特性变化。
随机对照试验。
受控实验室环境。
15只老年大鼠被随机分为对照组（CON）、后肢去负荷组（HU）和后肢去负荷并间歇性负重组（HU-IWB）。
HU组和HU-IWB组大鼠悬吊1周。HU-IWB组动物每天解除悬吊4次，每次允许15分钟负重。
肌肉重量、肌纤维直径、绝对峰值力、峰值比张力（P0）和最大缩短速度（V0）。
与CON组动物相比，HU组和HU-IWB组比目鱼肌（SOL）湿重分别显著降低19%和6%（p≤0.05）。SOL单纤维分析显示三组之间纤维直径无差异。然而，与CON组相比，HU组中SOL I型纤维的绝对峰值力和P0显著降低（p≤0.05）。HU组中SOL纤维的V0增加。与CON组动物相比，HU组和HU-IWB组腓肠肌（GAS）湿重分别显著降低9%和8%。
不活动显著改变了从老年哺乳动物SOL骨骼肌分离的单纤维的收缩特性。此外，最小限度的负重减轻了不活动对SOL诱导的这些有害影响。然而，这种负重方案并未减轻不活动诱导的老年哺乳动物GAS骨骼肌的改变。
