This New Scanner Tells You How Many Carbs to Eat and When
Think of MuscleSound as a fuel gauge for your body that helps optimize your diet and training plan
Over the past few months, in Boulder, Colorado, a growing number of elite athletes—including four-time U.S. cyclocross champion Jeremy Powers and Rio Olympic medalists Jenny Simpson (800-meter run) and Emma Coburn (steeplechase)—have added a new element to their training routines. At the end of a long day, after they’ve showered and refueled, these athletes wave a three-inch wand over their major leg muscles. On an adjacent screen, an image appears that, at first glance, looks like an ultrasound scan. Shortly thereafter appears a numerical score between zero and 100, which corresponds to the athlete’s level of glycogen, the body’s predominant fuel source for muscular energy. This new tool, called MuscleSound, is supposed to quantify the fine line between optimal and overtraining, revealing insights into the body that previously were left to imprecise estimates.
The MuscleSound score is closely linked to carbohydrates, which the body converts to muscle glycogen and thus remain king when it comes to a high-performance diet. The idea behind this new device is that by monitoring glycogen over a typical training week, an athlete can find the right balance between carb intake and training workload. A chronically low score means the athlete should either eat more carbohydrates or decrease training intensity and duration. If the reading is consistently 100, however, the athlete may actually need to cut back on carbohydrate intake, since carbs get turned into fat when muscle glycogen is topped off. (The body can store only about one pound’s worth of carbohydrates.) For a long time, measuring muscle glycogen required removing about a cubic square inch of muscle and analyzing it in a specialized lab. The procedure, called muscle biopsy, is invasive, expensive, and wholly impractical for regular use by athletes.