It may feel strange, look bizarre, and attract puzzled glances, but running with your arms straight may be as efficient as bending them at the elbow.

The surprising findings emerged after an academic researcher questioned the unthinking, near-universal habits of both walkers and runners.

“If straight arms are better for walking, why aren't they better for running, and vice versa?”, asked Andrew Yegian, a PhD candidate at Harvard University.

He subjected the question to scientific testing after his interest was aroused when he saw a straight-armed jogger pacing through the campus.

Mr Yegian and his team predicted a “mechanical tradeoff” exists between the elbow and shoulder joints which “would result in energetics that favoured straight arms during walking and bent arms during running”.

The researchers chose eight students for the study, ranging from serious marathon runners to those who ran around twice per week.

The subjects had oxygen masks and reflective markers put on their shoulders, elbows, and wrists before running and walking on a treadmill while their movements were filmed.

Confirming the first prediction, the results found having your arms straight while walking is more efficient, using around 11 per cent less oxygen than walking with bent arms.