Nagano Hanatsu, James Lisa, Sparrow William A, Begg Rezaul K
Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Ballarat Rd,, Footscray, Melbourne, Victoria, Australia.
J Neuroeng Rehabil. 2014 Nov 15;11:155. doi: 10.1186/1743-0003-11-155.
Fatigue and ageing contribute to impaired control of walking and are linked to falls. In this project, fatigue was induced by maximum speed walking to examine fatigue effects on lower limb trajectory control and associated tripping risk and overall gait functions of older adults.
Eleven young (18-35 years) and eleven older adults (>65 years) conducted 5-minute preferred speed treadmill walking prior to and following 6-minute maximum fast walking. Spatio-temporal gait parameters and minimum foot clearance (MFC) were obtained. Maximal muscle strength (hamstrings and quadriceps) was measured on an isokinetic dynamometer. Heart rate (HR) and rating of perceived exertion (RPE) assessed physiological effort and subjective fatigue. Physiological Cost Index computed walking efficiency.
Fatigue due to fast walking increased step length, double support time and variability of step width. Only older adults reduced MFC due to fatigue. A trend of longer double support with greater MFC was found in the non-dominant limb. Lower walking efficiency was characterised as the ageing effect. Older adults did not increase HR during fast walking but higher RPE scores were observed.
Older adults can increase tripping risk by 6 minutes of fast walking possibly by both impaired walking efficiency based on cardiac capacity and higher perceived fatigue due to elevated caution level. Regardless of age, increased step width variability due to fatigue was observed, a sign of impaired balance. Longer double support and greater MFC observed in the older adults' non-dominant limb could be an asymmetrical gait adaptation for safety.
疲劳和衰老会导致步行控制能力受损，并与跌倒有关。在本项目中，通过以最大速度行走来诱发疲劳，以研究疲劳对老年人下肢轨迹控制、相关绊倒风险和整体步态功能的影响。
11名年轻人（18 - 35岁）和11名老年人（>65岁）在6分钟最大速度快走之前和之后进行5分钟自选速度的跑步机行走。获取时空步态参数和最小足间隙（MFC）。在等速测力计上测量最大肌肉力量（腘绳肌和股四头肌）。心率（HR）和主观用力程度分级（RPE）评估生理努力和主观疲劳。计算生理成本指数以评估步行效率。
快速行走导致的疲劳增加了步长、双支撑时间和步宽变异性。只有老年人因疲劳而降低了MFC。在非优势肢体中发现了双支撑时间越长且MFC越大的趋势。较低的步行效率是衰老的特征。老年人在快速行走期间心率没有增加，但观察到较高的RPE分数。
老年人进行6分钟的快速行走可能会增加绊倒风险，这可能是由于基于心脏功能的步行效率受损以及由于谨慎程度提高而导致更高的主观疲劳感。无论年龄如何，均观察到因疲劳导致的步宽变异性增加，这是平衡受损的迹象。在老年人的非优势肢体中观察到更长的双支撑时间和更大的MFC，这可能是一种为了安全的不对称步态适应。
