Millions of us reach for a coffee at least once a day to boost our alertness and counter flagging energy levels.

我们中有很多人每天都至少需要一杯咖啡来提神醒脑，来增加我们消耗的能量。

But what if there was a free alternative that worked even better?

但要是有免费甚至效果更好的法子呢？

Writer Gregory Ferenstein believes he has the answer - 30 seconds of high-intensity exercise such as push-ups whenever he feels drowsy.

作家格雷戈里·弗兰斯坦觉得他就有这样的方法——当感到昏昏欲睡的时候，他通常会选择做30秒的高强度锻炼，比如做俯卧撑等。

He discovered that the exercises gave him double the energy boost of his daily Starbucks - and saved him a considerable amount of cash in the process.

他发现锻炼的提神效果是每日一杯星巴克咖啡的双倍，而且锻炼还能给他省掉一大笔咖啡钱。

He explained: 'Whenever I need a pick-me-up, I find a quiet corner and perform some form of body-weight exercise that jolts my heart up to at last 70 percent of the maximal beats per minute (for me, that's about 170).

他说：“当我需要提神了，我会去找一个安静的角落来做一些负重锻炼，来使我的心跳达到最快速度的70%（对我来说大约是每分钟170次）。”

He added: 'I've found that 30 seconds of high-intensity body-weight exercise gives me the same mental boost as a shot of caffeine.'

他补充说：“我发现，30秒高强度的负重锻炼和咖啡因一样，可以给人同样的精神刺激。 ”

For reference, a Starbucks Grande Cafe Americano has 225mg of caffeine. He found that his overall cognitive performance increased by six per cent after caffeine - but 12 per cent after exercise.

参考数据显示，星巴克一杯大杯美式咖啡中含有咖啡因225毫克。弗兰斯坦发现，咖啡因使他的整体认知能力上升了6%；而进行锻炼后，他的整体认知能力上升了12%。

The only benefit caffeine gave him was when it came to short-term memory, which improved by 26 per cent compared to 16 per cent with exercise.

咖啡因带来的好处是增强了26%的短期记忆力，比锻炼的效果高出10个百分点。

A wealth of research backs up his findings. Last year researchers at the Montreal Heart Institute found that high-intensity exercise boosts mental and physical health.

充分的研究也证实了弗兰斯坦的发现。去年蒙特利尔心脏研究所的研究人员发现，高强度的运动能增强身心的健康。

Previously sedentary adults were put through four months of high-intensity interval training.

在此之前，一些长期处于久坐状态中的人们接受了持续四个月的高强度的间歇训练。

At the end, their cognitive functions - the ability to think, recall and make quick decisions - had improved significantly, the researchers found.

在这项训练结束后，研究人员发现他们的认知能力，包括思考能力、记忆力以及迅速做事决定的能力等，都得到了大大的提升。

Last year researchers from the University of South Carolina found that regular treadmill sessions also give a boost to the cell's powerhouses in the brain.

去年南卡罗来纳大学的研究人员发现，定期在跑步机上进行跑步锻炼也能极大地促进脑细胞的生命力。