Took me ages to find any studies on this:

http://link.springer.com/article/10.1007/BF00424812

The above study looked at pedalling power output during maximal sprints.

After warming the legs in a 44‡ C water bath there was an increase of ∼11% in maximal peak force and power (PP_max) compared with normal rest while cooling the legs in 18 and 12‡ C water baths resulted in reductions of ∼12% and 21% respectively

http://onlinelibrary.wiley.com/doi/10.1111/j.1748-1716.1979.tb06439.x/abstract
This study looked at a variety of performance measures

 Maximal dynamic strength, power output, jumping, and sprinting performance were positively related to temperature