Onambélé Gladys L, Maganaris Constantinos N, Mian Omar S, Tam Enrico, Rejc Enrico, McEwan Islay M, Narici Marco V
Department of Exercise and Sport Science, Manchester Metropolitan University, Hassall Road, Alsager, ST7 2HL, UK.
J Biomech. 2008 Nov 14;41(15):3133-8. doi: 10.1016/j.jbiomech.2008.09.004. Epub 2008 Oct 31.
Loss of muscle strength and balance are main characteristics of physical frailty in old age. Postural sway is associated with muscle contractile capacity and to the ability of rapidly correcting ankle joint changes. Thus, resistance training would be expected to improve not only strength but also postural balance.
In this study, age-matched older individuals (69.9+/-1.3 years) were randomly assigned to flywheel (n=12), or weight-lifting (n=12) groups, training the knee extensors thrice weekly for 12 weeks. The hypotheses were that owing to a larger eccentric loading of the knee extensors, flywheel training would result in (a) greater gains in quadriceps strength; (b) greater improvements in balance performance compared with weight-lifting training. Isokinetic dynamometry, B-mode ultrasonography, electromyography, percutaneous muscle stimulation and magnetic resonance imaging were employed to acquire the parameters of interest.
Following training, knee extensors peak isokinetic power increased by 28% (P<0.01) in the flywheel group with no change in the weight-lifting group. Adaptations of the gastrocnemius muscle also occurred in both groups. The gastrocnemius characteristic with the highest response to training was tendon stiffness, with increases of 54% and 136% in the weight-lifting and flywheel groups, respectively (P<0.01). The larger increase in tendon stiffness in the flywheel group was associated with an improvement in postural balance (P<0.01).
Quadriceps flywheel loading not only produces a greater increase in power than weight training but its physiological benefits also transfer/overspill to the plantarflexor muscle-tendon unit resulting in a significantly improved balance. These findings support our initial hypotheses.
肌肉力量和平衡能力的丧失是老年人身体虚弱的主要特征。姿势摇摆与肌肉收缩能力以及快速纠正踝关节变化的能力有关。因此，抗阻训练不仅有望增强力量，还能改善姿势平衡。
在本研究中，将年龄匹配的老年人（69.9±1.3岁）随机分为飞轮训练组（n=12）或举重训练组（n=12），每周对膝关节伸肌进行三次训练，共12周。假设是，由于膝关节伸肌的离心负荷更大，飞轮训练将导致：（a）股四头肌力量有更大的提升；（b）与举重训练相比，平衡能力有更大的改善。采用等速测力法、B超、肌电图、经皮肌肉刺激和磁共振成像来获取相关参数。
训练后，飞轮训练组膝关节伸肌的等速峰值功率增加了28%（P<0.01），而举重训练组无变化。两组的腓肠肌也都发生了适应性变化。对训练反应最高的腓肠肌特征是肌腱僵硬度，举重训练组和飞轮训练组分别增加了54%和136%（P<0.01）。飞轮训练组肌腱僵硬度的更大增加与姿势平衡的改善相关（P<0.01）。
股四头肌的飞轮负荷不仅比重量训练产生更大的功率增加，而且其生理益处还转移到跖屈肌肌腱单元，从而显著改善平衡。这些发现支持了我们最初的假设。
