I thought this paper in PLoS Biology from a couple years back was pretty interesting/funny given that I have some interest in the evolutionary ecology and genetics of muscle physiology and sports.
Here's a video of the transgenic mouse that keeps on running, while the wild-type is getting exhausted. By the way, exhaustion is defined as being "unable to avoid repetitive electrical shocks."... poor mice!
Regulation of Muscle Fiber Type and Running Endurance by PPARδ
Yong-Xu Wang, Chun-Li Zhang, Ruth T. Yu, Helen K. Cho, Michael C. Nelson, Corinne R. Bayuga-Ocampo, Jungyeob Ham, Heonjoong Kang, Ronald M. Evans*
Abstract: Endurance exercise training can promote an adaptive muscle fiber transformation and an increase of mitochondrial biogenesis by triggering scripted changes in gene expression. However, no transcription factor has yet been identified that can direct this process. We describe the engineering of a mouse capable of continuous running of up to twice the distance of a wild-type littermate. This was achieved by targeted expression of an activated form of peroxisome proliferator-activated receptor δ (PPARδ) in skeletal muscle, which induces a switch to form increased numbers of type I muscle fibers. Treatment of wild-type mice with PPARδ agonist elicits a similar type I fiber gene expression profile in muscle. Moreover, these genetically generated fibers confer resistance to obesity with improved metabolic profiles, even in the absence of exercise. These results demonstrate that complex physiologic properties such as fatigue, endurance, and running capacity can be molecularly analyzed and manipulated.
A few genes implicated in type I and type II muscle fibers, or associated with endurance vs. sprint performance have been found in humans but those are not mentioned in this paper. I wonder if anyone has looked at PPAR in humans.