Daily exercise could make people more productive in their routine work, according to a New Zealand study of rats on Friday.

Otago University researchers found that rats which ran 20 minutes a day for five days a week outperformed their non-exercised counterparts across the board in laboratory tasks.

The exercised rats completed more tasks and did so more quickly and efficiently, which enabled them to earn more food rewards, study lead author Dr Kristin Hillman said in a statement.

"We all know exercise is good for our physical and mental health, but this data suggests that regular exercise may also help make you more productive when it comes to getting tasks accomplished each day," said Hillman.

"Links between exercise and occupational/educational achievement are starting to be noted in humans, but these links are largely correlations and can be riddled with confounding psychosocial factors. These factors include family environment, socio-economic status and personality traits," she said.

"By using an animal model we obviously eliminate such factors, and are able to demonstrate a causal relationship between regular exercise and generalized industriousness."

The next step would be to figure out the neural mechanisms responsible for the effect.