May 19, 2015
Ultrasound for Muscles
May 19, 2015
May 19, 2015
Muscles need lots of supplies to keep them moving. They need high-energy molecules, calcium, salts and most importantly sugars.
Our long stringy muscle fibers keep a plentiful store of sugar in the form of glycogen to keep them fueled through long exercise. And as marathon runners and long distance cyclists can tell you, when the glycogen runs out, it’s not pretty.
That is why you can see elite endurance athletes consume sugary foods — gels, sports drinks, some marathoners even drink flat soda — in the middle of a race. Many Olympic level athletes will hire labs to test how quickly their muscles use up glycogen, so the athlete can plan when and exactly how much sugar to take on in a race.
Those tests, however, are typically done via muscle biopsy, which involves using a long needle to pull out pieces of the athletes’ muscle tissue. These procedures can be painful, and involve both local anesthetic and stitches, which can interfere with the athlete’s training.
Now according to a new study from the North Carolina Research Campus, scientists can test for muscle glycogen using a new ultrasound technique.
This portable ultrasound machine — called MuscleSound and developed by a Colorado company of the same name — works similarly to other ultrasounds where a probe bounces sound waves off tissues to create a picture.
Unlike a standard sonogram, like what doctors use to monitor babies, MuscleSound tracks the intensity of the picture instead of the shape. The picture grows brighter and brighter as glycogen is depleted and MuscleSound converts that change in brightness to the amount of glycogen use in muscle cells. What’s better is that MuscleSound can do this non-invasively and with no risk to the patient.
Dr. David Nieman of the Human Performance Laboratory in Kannapolis compared MuscleSound’s results to muscle biopsy results in 20 cyclists. Nieman took ultrasound scans and biopsies of the cyclists’ vastus lateralis (front outer thigh) muscles before and after a 75 kilometer ride.
The results showed that the MuscleSound measurements showed a statistically significant correlation of 92%, or not quite dead on but very close.
Athletes and trainers have a powerful tool in this new technology. They can design diets to keep glycogen at its best levels and determine when in a long competition they need to take on more sugar.
Nieman also says that MuscleSound opens up several other muscle groups to glycogen studies. The deltoid muscles in the shoulder have not been studied as extensively because the shoulder area is full of complex bones, nerves and blood vessels that make biopsies difficult and somewhat risky. MuscleSound provides a risk-free way to now study these muscles.
The paper describing this study appeared in the journal, BMC Sports Science.
— Daniel Lane
Daniel Lane covers science, engineering, medicine and the environment in North Carolina.