"People who would like to become physically stronger should start with weight training and add protein to their diets, according to a comprehensive scientific review of research," Gretchen Reynolds writes. "The review finds that eating more protein, well past the amounts currently recommended, can significantly augment the effects of lifting weights, especially for people past the age of 40. But there is an upper limit to the benefits of protein, the review cautions."
According to "Witness the Fitness: A Look at Workout Trends Across the Country," Google searches for "physical fitness" peak in January every year, and more of these searches are now happening on mobile. What are other rising fitness trends? Here are some ways for retailers and gyms to capture