Cotter Joshua A, Yu Alvin, Haddad Fadia, Kreitenberg Arthur, Baker Michael J, Tesch Per A, Baldwin Kenneth M, Caiozzo Vincent J, Adams Gregory R
1Department of Physiology and Biophysics, University of California, Irvine, CA; 2Department of Orthopaedic Surgery, University of California, Irvine, CA; 3Department of Kinesiology, California State University, Long Beach, CA; and 4Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, SWEDEN.
Med Sci Sports Exerc. 2015 May;47(5):990-1000. doi: 10.1249/MSS.0000000000000483.
The objective of this study is to examine the effect of a high-intensity concurrent training program using a single gravity-independent device on maintaining skeletal muscle function and aerobic capacity during short-term unilateral lower limb suspension (ULLS).
Nineteen subjects (10 males and 9 females; 21.0 ± 2.5 yr, 65.4 ± 12.2 kg) were separated into two groups: 1) 10-d ULLS only (n = 9) and 2) 10-d ULLS plus aerobic and resistance training (ULLS + EX, n = 10). Exercise was performed on a single gravity-independent Multi-Mode Exercise Device (M-MED) with alternating days of high-intensity interval aerobic training and maximal exertion resistance training.
Aerobic capacity increased by 7% in ULLS + EX (P < 0.05). Knee extensor and ankle plantar flexor three-repetition maximum increased in the ULLS + EX group (P < 0.05), but this change was only different from ULLS in the plantar flexors (P < 0.05). Peak torque levels decreased with ULLS but were increased for the knee extensors and attenuated for the ankle plantar flexors with ULLS + EX (P < 0.05). A shift toward type IIx myosin heavy-chain mRNA occurred with ULLS and was reversed with ULLS + EX in the vastus lateralis (P < 0.05) but not the soleus. Myostatin and atrogin increased with ULLS in both the vastus lateralis and soleus, but this change was mitigated with ULLS + EX only in the vastus lateralis (P = 0.0551 for myostatin, P < 0.05 for atrogin). Citrate synthase was decreased in the soleus during ULLS but was increased with ULLS + EX (P < 0.05).
These results indicate that an M-MED class countermeasure device appears to be effective at mitigating the deconditioning effects of microgravity simulated during a modified ULLS protocol.
本研究的目的是检验使用单一非重力依赖设备的高强度同步训练计划对在短期单侧下肢悬吊（ULLS）期间维持骨骼肌功能和有氧能力的影响。
19名受试者（10名男性和9名女性；21.0±2.5岁，65.4±12.2千克）被分为两组：1）仅进行10天的ULLS（n = 9）和2）10天的ULLS加上有氧和阻力训练（ULLS + EX，n = 10）。运动在单一的非重力依赖多模式运动设备（M-MED）上进行，高强度间歇有氧训练和最大用力阻力训练交替进行。
ULLS + EX组的有氧能力提高了7%（P < 0.05）。ULLS + EX组的膝伸肌和踝跖屈肌的三次重复最大值增加（P < 0.05），但这种变化仅在跖屈肌中与ULLS不同（P < 0.05）。峰值扭矩水平随ULLS降低，但在ULLS + EX组中，膝伸肌的峰值扭矩水平增加，踝跖屈肌的峰值扭矩水平减弱（P < 0.05）。在股外侧肌中，ULLS导致向IIx型肌球蛋白重链mRNA转变，而ULLS + EX使其逆转（P < 0.05），但比目鱼肌中未出现这种情况。股外侧肌和比目鱼肌中的肌生长抑制素和萎缩素随ULLS增加，但这种变化仅在股外侧肌中通过ULLS + EX得到缓解（肌生长抑制素P = 0.0551，萎缩素P < 0.05）。在ULLS期间比目鱼肌中的柠檬酸合酶减少，但在ULLS + EX时增加（P < 0.05）。
这些结果表明，一种M-MED类对抗措施设备似乎能有效减轻在改良ULLS方案中模拟的微重力的去适应效应。
