澳大利亚一项研究显示，步行速度快的老年人死亡率较步速慢的老年人低。
步速快的人生存率高
悉尼康科德医院研究人员随访1700名70岁以上男性，定期记录下这些老人步行6米所需要的时间。5年后，研究人员分析这些老年人步行速度与死亡率间关系。
统计结果显示，受调查老人的平均步速为每秒0.88米，即时速3.168公里。其中，走路最慢的人每秒钟只能走0.15米，相当于时速0.54公里；走路最快的人每秒钟可以走1.5米，合时速5.4公里。
研究期间，共有266名老人去世，这些人走路速度比同龄人慢。生存率分析显示，步行速度大于时速2.95公里的老人死亡率比走路慢者低近20%，步行速度大于时速4.8公里的老年人生存率最高。
研究报告由最新一期《英国医学杂志》周刊发表。
跟踪调查耗时5年
法国研究人员先前也曾做过类似研究。他们跟踪调查3200名身体健康、年龄65岁以上的老年人，记下这些人的步速。整个研究耗时5年。
调查期间共有209人去世，其中99人死于癌症，59人死于心血管疾病。研究人员发现，与走路最快的三分之一调查对象相比，走路最慢的三分之一老年人总体死亡风险高44%，因疾病死亡的风险高200%，因心脑血管疾病死亡的风险高300%。
研究人员说，走路慢的人通常年龄大、身材矮小、身高体重指数（BMI）大、有抑郁症状、受教育程度低、运动量小。
体力活动有助预防癌症
美国宾夕法尼亚大学老年医学专家安妮•卡普波拉接受微软—全国广播网（MSNBC）采访时说，老年人保持健康的秘诀在于运动，缺乏运动会引发一系列问题。
“人们尝试抗阻力训练等力量训练并试图多走路来锻炼身体，但这对活动范围有限的老年人而言难度较大，”她说，老年人可以尝试走得快一些，这也在一定程度上有益健康。
英国“世界癌症研究基金会”说，快走可加快心跳，促进呼吸，属于可防癌的“适度体力活动”方式之一。 基金会去年推出“一起快走”活动，号召参与者与家人、朋友一起快走，鼓励参与者养成有助于降低患癌风险的习惯。
世界癌症研究基金会说，尽管有证据表明体力活动有助预防癌症，“但只有大约三分之一民众意识到这一点，要提高认识还有不少工作要做”。
How fast does the Grim Reaper walk? Receiver operating characteristics curve analysis in healthy men aged 70 and over
Fiona F Stanaway, Danijela Gnjidic, Fiona M Blyth, David G Le Couteur, Vasi Naganathan, Louise Waite, Markus J Seibel, David J Handelsman, Philip N Sambrook, Robert G Cumming
Objective To determine the speed at which the Grim Reaper (or Death) walks.
Design Population based prospective study.
Setting Older community dwelling men living in Sydney, Australia.
Participants 1705 men aged 70 or more participating in CHAMP (Concord Health and Ageing in Men Project).
Main outcome measures Walking speed (m/s) and mortality. Receiver operating characteristics curve analysis was used to calculate the area under the curve for walking speed and determine the walking speed of the Grim Reaper. The optimal walking speed was estimated using the Youden index (sensitivity+specificity−1), a common summary measure of the receiver operating characteristics curve, and represents the maximum potential effectiveness of a marker.
Results The mean walking speed was 0.88 (range 0.15-1.60) m/s. The highest Youden index (0.293) was observed at a walking speed of 0.82 m/s (2 miles (about 3 km) per hour), corresponding to a sensitivity of 63% and a specificity of 70% for mortality. Survival analysis showed that older men who walked faster than 0.82 m/s were 1.23 times less likely to die (95% confidence interval 1.10 to 1.37) than those who walked slower (P=0.0003). A sensitivity of 1.0 was obtained when a walking speed of 1.36 m/s (3 miles (about 5 km) per hour) or greater was used, indicating that no men with walking speeds of 1.36 m/s or greater had contact with Death.
Conclusion The Grim Reaper’s preferred walking speed is 0.82 m/s (2 miles (about 3 km) per hour) under working conditions. As none of the men in the study with walking speeds of 1.36 m/s (3 miles (about 5 km) per hour) or greater had contact with Death, this seems to be the Grim Reaper’s most likely maximum speed; for those wishing to avoid their allotted fate, this would be the advised walking speed.
