Taking exercise before work is more effective if you have a stressful job, as mental fatigue can affect physical performance, say scientists.
Researchers found mentally tired people will reach physical exhaustion quicker than those that have a rested mind.
Physiologists at Bangor University discovered that even though being exhausted after work did not actually affect your muscles, it did make it harder for people to exercise so vigorously.
They believe that it makes people "perceive" that exercise is more strenuous and could lead to treatment for chronic fatigue syndrome.
"People with chronic fatigue report that they lack energy and experience 'brain fog', just like the mentally fatigued participants in this study," said Dr Samuele Marcora.
"In addition, as in this study, people with chronic fatigue perceive exercise to be more difficult despite physiological responses considered normal during exercise."
The study suggests that athletes and stressed workers would be better to train when their minds are fresh although researchers said any exercise was still beneficial.
"People who exercise after work should continue doing so, even if mentally fatigued, "Dr Marcora said.
"Most people work out at a moderate intensity, which still gives plenty of physiological and psychological benefit, including relief from stress and improved mental performance."
The scientists came to their conclusions after 16 volunteers were asked to exercise on a bike, half the time when their mind was fresh and half the time after 90 minutes of mentally fatiguing work.
Participants stopped exercising on average 15 per cent earlier when they were mentally fatigued.
this news will be very good for people who suffer from work stress
