Runners need to move 15 per cent faster on a treadmill¹ to burn the same number of calories as jogging outdoors, research reveals.

一项研究表明，跑步者在跑步机上的速度要比户外慢跑快15%，才能与其燃烧同等热量。

Researchers from Milan University analysed the difference between running outdoors or on a treadmill in 15 physically² fit males with an average age of 21.

意大利米兰大学的研究人员分析了平均年龄为21岁的15名健康男子去户外跑步与在跑步机上跑步的差异。

The participants sprinted³ for 30 seconds followed by 30 seconds of recovery for a total of 15 minutes both outdoors and on a treadmill.

参与者先快跑30秒，然后休息30秒，这样分别在户外和跑步机上运动15分钟。

Oxygen use and exercise intensity⁴ were measured after both types of running. The findings were published in the journal of Applied⁵ Physiology⁶, Nutrition and Metabolism⁷.

研究人员会在两种类型的跑步后，测量参与者的耗氧量和运动强度。研究成果发表在加拿大《应用生理学、营养与代谢》杂志上。

Results revealed that when on a treadmill, runners use significantly lower amounts of oxygen, suggesting less effort is required.

结果显示，在跑步机上跑步时，跑步者的耗氧量大大降低，表明这种方式更省劲。

The study authors wrote: 'A 15 per cent increase in running velocity⁸ during a high intermittent⁹ intensity treadmill training session is the optimal¹⁰ solution to reach the same physiological¹¹ responses as an outdoor training session.'

该研究的作者写道：“在高间歇强度跑步机训练期间，跑步速度增加15%，是达到与户外锻炼同样生理反应的最佳解决方案。”

Although the study did not speculate why treadmill running appears to be less strenuous¹², previous research suggests the moving belt of a treadmill propels joggers forward, causing them to move faster.

尽管这项研究没有推测为何在跑步机上跑步似乎更省力，但以往的研究指出，跑步机上移动的跑带会推动跑步者向前，从而让他们跑得更快。

Exercising indoors also means gym-goers do not have to contend with steep hills or wind resistance.

此外，室内锻炼还意味着锻炼者不必应付陡峭的山坡或风的阻力。