Why do we become clumsy after a hard training? Apparently it's all upstairs....

 
As exhausted Olympic athletes stagger across the finish line after a grueling endurance event, Australian scientists have for the first time revealed what lies behind the stumbling gait and the clumsy movements that accompany exhaustion.

A research team in the Department of Physiology at Monash University studied how people, with their eyes closed, can locate the position of their arms in space, before and after exercising one arm to exhaustion.

They found that before exercise, most people could align their arms to within one to two degrees. After exercise, arm position was significantly awry, even though the people insisted that their arms were perfectly aligned.

'Our research broke new ground,' says Professor Uwe Proske, leader of the research team. 'Initially, we thought that damage within the fatigued muscles themselves causes the clumsiness. Instead we discovered that this loss of knowing where your limbs are originates in the brain, and it occurs after all kinds of strenuous exercise'.

The brain, operating with gravity, is able to calculate and match the effort required for placing limbs in particular positions. However, 'fatigued muscles need to use much greater effort to reach and maintain a position', according to Professor Proske. 'That is what leads to trouble.'
When the people in the Monash study simply matched efforts in their non-fatigued and fatigued arms, this led to the alignment errors.
Gravity plays a part by 'giving people cues as to where their limbs are'.

'Reduced gravity is the reason why astronauts in space, don't know where their limbs are when they cannot see them,' says Professor Proske. 'The same is true of SCUBA divers.'

So, if your left hand doesn't know what your right hand is doing, and you're not in microgravity conditions (or drunk), then the only thing for it is to relax and recuperate.