The relationship between muscle types and body metabolism has been under investigation for decades, but the most recent research challenges the long-held belief that whitening of skeletal muscle is harmful. White muscle increases with resistance training, age and diabetes (which is where the negative link stems from) but it appears that white muscle may actually help keep blood sugar levels in check.
There are a range of muscle types: red, white and in between. Red muscle is most abundant in people who engage in endurance training regularly and white muscle dominates those who require strength and power for their sport.
The majority of people have a relatively equal mix, but this shifts in accordance with training demands. The red-to-white shift was thought to make muscle less responsive to insulin, but this is not proven. In humans, resistance training promotes the growth of white muscle and helps in lowering blood glucose.
Researchers set out to find the protein which drives the formation of white muscle. Further studies led the team to focus on a protein called BAF60c, a sort of ‘zip code’ mechanism that tells cells how and when to express certain genes.
If future studies in humans determine that this pathway (BAF60c) is indeed the way in which cells form white muscle and in turn optimise metabolic function, the finding could lead to researching the pathway as a drug target for obesity and diabetes.
Zhuo-Xian Meng, Siming Li, Lin Wang, Hwi Jin Ko, Yongjin Lee, Dae Young Jung, Mitsuharu Okutsu, Zhen Yan, Jason K Kim, Jiandie D Lin, BAF60c Drives Glycolytic Metabolism in the Muscle and Improves Systemic Glucose Homeostasis Through Deptor-Mediated Akt Activation, Nature Medicine, 2013.