The soleus muscle in the calf, though only 1% of your body weight, can do big things to improve the metabolic health in the rest of your body if activated correctly.Marc Hamilton, professor of Health and Human Performance at the University of Houston, has discovered such an approach for optimal activation – he’s pioneering the “soleus pushup” (SPU) which effectively elevates muscle metabolism for hours, even while sitting. The soleus, one of 600 muscles in the human body, is a posterior leg muscle that runs from just below the knee to the heel.