Measuring Muscles Like Batteries: NFL Teams Turn to Ultrasound, Seeking an Edge

MuscleSound, a Denver company, is working with NFL teams to gauge the energy efficiency of players’ muscles, allowing them to tailor workouts and nutrition to stay on the field

With the NFL opener done and dusted, the season grind starts. From now until the end of December, all 32 franchises will try to balance performance with recovery. And the few teams lucky enough to reach the postseason may have to keep playing that game all the way through to Feb. 4, 2018.

Winning championship rings is partly about who can best perfect that tradeoff. Losing too many players to injury or illness can wreck a season, but being too healthy might mean you didn’t spend enough time in the pain cave. Last year’s top four teams on Football Outsiders’ Adjusted Games Lost statistic didn’t make the postseason. Super Bowl LI’s two contenders, New England and Atlanta, were No. 8 and No. 6, respectively, in terms of keeping their players on the field.

A handful of teams have turned to a Denver-based company called MuscleSound to understand how close they might be to the line. MuscleSound uses ultrasound scans to determine energy stores in athletes’ muscles, in the form of glycogen level, providing an overall “fuel rating” from zero [empty] to 100 [full]. The idea is that knowing how much each game drains an athlete’s batteries, and checking to see if they’ve been recharged sufficiently by the next game, will help teams fashion personalized training and nutrition schedules for each player.

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Because NFL teams are often secretive about whom they work with, the company was reluctant to provide a list of clients. However, according to CEO Andy Jackson, that group includes at least one of last season’s main playoff contenders. To highlight how teams use MuscleSound, Jackson tells the story of an offensive lineman from that team who was first scanned in June 2016. “This particular lineman rocked up at the start of training camp under 25,” Jackson says. (For reference, an average lineman might be expected to leave camp with a fuel rating drained down to about 70.) “[He] had always had problems with being injured, and had never played more that 12 or 13 games in a season.”

When MuscleSound’s director of performance, John Ireland, sat down with the team’s nutritionist and the player to discuss what might be wrong, they discovered he had switched to a low-carb diet in an effort to make weight. The problem was that while he may have been shaving pounds, his diet wasn’t refueling his muscles sufficiently, reducing overall performance and increasing his susceptibility to injury. The solution was to switch back to a more balanced diet and lessen his focus on body weight.

“By the end of the training camp he was up to 60 or 75 [fuel rating],” Jackson says. “He played the full season—every single game—played into the playoffs for this particular team, and had his best season.”

Muscles are scanned using a handheld ultrasound probe that can be hooked up to a computer, a tablet or even just an Android phone. The probe projects sound waves through the body and measures their reflection off different tissues to create an image of each muscle. A small amount of gel is applied between the probe and the skin to help transmit the sound, and each muscle takes about a minute to analyze. Compared to research performed by co-founders Iñigo San Millán and John Hill, both professors at the University of Colorado’s school of medicine, to calibrate the system, the gel and the time delay (which becomes hours when considering multiple muscles and an entire football roster), is a minor inconvenience. In their study, San Millán and Hill biopsied cyclists’ quadriceps using needles.

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The body converts the carbohydrates you eat into a molecule called glycogen, and this gets converted into glucose when energy is needed. In muscles, glycogen is stored with water—three to four parts water for every part glycogen. “That’s what we use to look at glycogen content,” San Millán explains. “When there is a lot of glycogen … there’s a lot of water associated with that.” The different structures surrounding muscle—bone, fascia, connective tissue—all reflect different wavelengths, allowing them to be imaged using ultrasound. The water stores, though, absorb the sound waves, creating a darker image, and this darkness indicates the presence of glycogen.

Founded in 2011, MuscleSound has so far scanned the muscles of 2,400 athletes in a range of sports including cycling, soccer, basketball and baseball—the Rockies are in the fifth year of a partnership. San Millán is the director of the sports performance program at Colorado, so the Buffaloes are a natural collaborator, and the company also counts Oregon State and South Carolina as clients.

While MuscleSound doesn’t promote specific links within the NFL, there are hints online as to which teams might have taken an interest. Tech.Co, a website that tracks startup companies, reported that the Rams were clients of MuscleSound in 2015, and The18.com named Ireland as a consultant for the Cowboys in a story published in January. The company was also featured on the Patriots’ Tackling Tech blog in July, so you can be sure that Bill Belichick’s strength and conditioning staff are at least aware of MuscleSound.

Last Friday, Ireland was keeping an eye on data streaming in from one of MuscleSound’s NFL clients. The team was scanning players to assess recovery levels ahead of its game on Sunday, in case any corrective action might be needed in the final run-up to the season. As well as providing a numbered fuel rating, MuscleSound color codes players: green for OK, teal for caution and red when there might be a problem.

Two of the players on the team in question flagged up red. Ireland jumped on the phone with the head of performance to discuss possible interventions. “The best recovery is sleep, and quality sleep,” Ireland says. “That’s the best intervention there is, but that’s hard.” Other options after a heavy training week might include adjusting nutrition to refuel muscles, or massage and ice baths to promote healing, followed by reassessment using ultrasound to see what worked.

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The potential for muscle ultrasound goes deeper than just overall fuel ratings. Scanning individual muscles for glycogen levels can indicate how to adjust workouts. If arm muscles are depleted, perhaps today is not an arm day in the gym. But if the legs are OK, it is also not a rest day. Comparison of muscles between the left and right side might indicate imbalances that could lead to injury, or help trainers understand how an athlete’s rehab is going post-injury.

Glycogen stores also appear to work more like batteries than a car’s fuel tank. A player won’t run at full speed until his glycogen is gone—instead his spark will slowly fade as the level is depleted. Perhaps that might mean that in future teams will look to measure glycogen stores not just before a game but also during breaks in play. Winning a tight game might not be about picking the players who were fastest and strongest in workouts, but who still have enough to give at game’s end.

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