I have come across an article that discusses among other properties, shortening speed and temperature: Human skeletal muscle fibres: molecular and functional diversity; Bottinelli, Reggiani; Progress in Biophysics and Molecular Biology, 2000.
You can buy it on-line (I got a copy from my local University). It’s above my level, so I’m not able to really explain it. But it does say, I quote: “Vo of human fibres shows a very striking dependence on temperature.” Vo is defined as Unloaded shortening velocity. I’m not sure if this applies to this discussion, but I may reread the section and try to report it in here if you are interested.