Weerdesteyn Vivian, Nienhuis Bart, Geurts Alexander C H, Duysens Jacques
Department of Rehabilitation Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
J Gerontol A Biol Sci Med Sci. 2007 Sep;62(9):1042-7. doi: 10.1093/gerona/62.9.1042.
Obstacles in the travel path are a frequent cause of falls among elderly persons. In obstacle avoidance under time pressure, elderly persons have been reported to be less successful than young persons, but possible age-related deficits at the neuromuscular control level have not been studied yet.
In the present study, obstacle avoidance reactions were investigated in 15 young and 9 older adults. While the participants walked on a treadmill, an obstacle was dropped in front of the left foot either in late stance, early swing, or mid-swing. Muscle activity in response to the obstacle was measured from the left biceps femoris (BF), rectus femoris (RF), tibialis anterior (TA), and medial head of gastrocnemius (GM). Avoidance success rates, as well as initial response latencies and response amplitudes over the first 50 ms of the response, were determined.
In both young and older adults, a large initial response was consistently observed in BF at very short latencies (104-111 ms in the young group), especially for mid-swing obstacle presentations (yielding the highest time pressure). Onset latencies in the elderly group were delayed by 10 ms on average. Response amplitudes were larger in young than in older adults, most prominently in BF and RF, but with a similar tendency in TA. Both onset latency and response amplitude were significantly associated with avoidance success rates.
The results of the present study suggest that age-related deficits in the neuromuscular control of obstacle avoidance could play a role in the large numbers of obstacle-related falls in the elderly population.
行走路径中的障碍物是老年人跌倒的常见原因。据报道，在时间压力下进行避障时，老年人不如年轻人成功，但尚未研究神经肌肉控制水平上可能存在的与年龄相关的缺陷。
在本研究中，对15名年轻人和9名老年人的避障反应进行了调查。当参与者在跑步机上行走时，在左足的支撑后期、摆动前期或摆动中期将一个障碍物置于其前方。测量左侧股二头肌（BF）、股直肌（RF）、胫骨前肌（TA）和腓肠肌内侧头（GM）对障碍物的肌肉活动。确定避障成功率以及反应最初50毫秒内的初始反应潜伏期和反应幅度。
在年轻人和老年人中，均在极短潜伏期（年轻组为104 - 111毫秒）时在BF中持续观察到较大的初始反应，特别是对于摆动中期的障碍物呈现（产生最高时间压力）。老年组的起始潜伏期平均延迟10毫秒。年轻人的反应幅度大于老年人，在BF和RF中最为明显，但TA中也有类似趋势。起始潜伏期和反应幅度均与避障成功率显著相关。
本研究结果表明，与年龄相关的避障神经肌肉控制缺陷可能在老年人群中大量与障碍物相关的跌倒中起作用。
