Before every practice and game, the Michigan men's basketball players pull up their shorts, tie the laces on their Jordan sneakers, and put on what at first glance look like sports bras.

What might seem like an odd fashion choice is being hailed as a game-changer for the No. 23 Wolverines.

Nestled in the back of the compression garment, between the shoulder blades, is a slot for an electronics device that monitors how hard players are working on the court, providing insights to coaches regarding practice habits, game preparation, and injury prevention.

Manufactured by the Australian analytics company Catapult Sports, the device is four inches tall, weighs two ounces, and has made a believer out of Michigan head coach John Beilein.

"This whole Catapult system is changing our world," he says.

The OptimEye S5 is a plastic, black and orange device that sends information to a laptop, which Michigan's training staff analyzes to better understand how much effort players are exerting. This exercise isn't just for fun or curiosity. It has a direct impact on how Beilein runs practice.

The Catapult device tracks movement in three dimensions: forward/backward, sideways, and vertically. It has an accelerometer that captures sudden bursts hundreds of times per second. Catapult's most important output is a proprietary measure called PlayerLoad. It is a single number that measures exertion, not dependent on distance, as Crisler Center is not wired for GPS tracking ("That would be nice but not necessary," says U-M head strength and conditioning coach Jon Sanderson).

The Michigan men's basketball program started using Catapult in February of 2016 on a trial basis. The system really turned heads halfway through last season when then-senior point guard Derrick Walton, Jr. wasn't playing as well as he and the Michigan coaches expected.

Walton had a reputation as a fierce competitor, and at times it worked against him. At practice, he gave max effort in drills and didn't like subbing out when the rotation players scrimmaged against the scout team. As a result, he appeared tired in games, averaging 12.6 points and 3.4 assists in Michigan's first 20 games.

A typical PlayerLoad for a Division I college basketball game is about 1,000. Walton was hitting that number every practice, while his teammates were topping out around 800. By last January, according to Sanderson, "We had enough data and we came to the realization that (Walton) was doing too much."

Beilein had Sanderson and trainer Alex Wong, who monitor Catapult data in real-time during practice, inform him of Walton's numbers. The staff no longer wanted Walton's PlayerLoad to exceed 600 the day before a game, so Sanderson or Wong would tell Beilein when Walton reached 300.

It wasn't easy for Walton to observe instead of participate, but he couldn't argue with the results. As his practice load decreased, his performance in games rose to unforeseen heights. In Michigan's final 18 games, Walton averaged 18.7 points and 6.6 assists. With Walton playing at an All-America level, Michigan won a Big Ten Tournament title and advanced to the Sweet 16.

FOR SEVERAL YEARS, Michigan basketball players wore heart monitors during practice. As companies like Catapult, Zephyr, and others popped up, Michigan wanted to do more.

"We wanted to step up and get an advanced system to track what we were doing in practice and games," Sanderson says. "This whole sports science industry has boomed over the last five years. It's amazing what's out there."

The school signed a three-year contract with Catapult in July 2016. During that span, Catapult provides equipment, software, and support at a cost of about $1,400 per year per student-athlete, according to Darryl Conway, an associate AD at Michigan and the school's chief health and welfare officer.

In addition to men's basketball, which has 12 individual devices, six other U-M teams are using Catapult: women's basketball (13 devices), women's soccer (18), field hockey (18), ice hockey (18), football (15), and men's lacrosse (28). Add it up and the partnership costs Michigan approximately $170,800 per year.

"It was something we felt was important for our student-athletes, to get into the performance monitoring and injury prevention space," Conway says.

Men's basketball powers Kentucky and Duke also use Catapult. In the Big Ten, Nebraska, Rutgers, Northwestern, and Iowa do as well. Purdue and Maryland use a competing company's products, though only in practice. Michigan State, Wisconsin, Ohio State, and Illinois don't use such a device, while spokespeople at Minnesota, Penn State, and Indiana did not respond to a request for information.

The technology has its critics who question the usefulness of the data.

Isaiah Kacyvenski, managing director of the Sports Innovation Lab, believes wearable tech has not delivered on it promises, telling the New York Times in September that investor interest in the subject has waned.

"Even if you nail it on an accuracy level," he told the , "what does it mean?"

There is no shortage of teams, however, who apparently think they know or can find out.

A Catapult rep says 150 colleges are clients, including 20 to 25 Division I men's basketball teams, as well as 16 NBA teams.

Unlike many of those programs, Michigan has students assisting with data analysis. In addition to the basketball staff, Michigan's School of Information dean, Thomas Finholt, oversees a group of undergrads who examine the Catapult numbers. The students' majors include computer science, statistics, and economics, among others. Beginning this season, they've attended practices and games to monitor real-time data feeds in addition to working on various independent study projects.

COACHES ACROSS SPORTS, generally speaking, tend to over-prepare for games. Count Beilein among the coaches who always wishes he had more time to get his team ready for competition. Catapult has allowed him to quantify a player's workload and better manage the days leading up to a game.

"For 40 years, I had no idea," he says. "It was all my feel for how tired they looked."

The Michigan basketball staff used the trial period and the first half of last season to acquire data on its players. This allowed them to establish baselines for individuals. For freshmen, the staff can pull data from preseason workouts but also group players by size. The 6-foot Zavier Simpson is naturally going to have a higher PlayerLoad than the 7-foot-1 Jon Teske because Teske doesn't need to take as many steps to move across the court or jump as high to reach the rim. It doesn't mean smaller players work harder than big guys, just that the threshold is typically lower for a longer athlete.

When official preseason practices begin, the Michigan coaches are focused on gradually increasing PlayerLoad to reduce the chance of injury. Going from, say, a 300 PlayerLoad one day to 1,300 the next is not ideal.

"That accumulation of fatigue ramps up quickly and you're more likely to get hurt," Sanderson says.

During the season, the PlayerLoad metric helps players get the right amount of work. The guys who played heavy minutes in the prior game -- this season, that's typically been Muhammad-Ali Abdur-Rahkman, Charles Matthews, Moritz Wagner, and Duncan Robinson -- are given a lot of rest in the two days leading up to the next game.

The staff can make connections between specific drills and the PlayerLoad they generate, which allow Beilein to plan practice more efficiently.

"I can go to Coach and say, 'Here's kind of your menu from low to medium to high drills,'" Wong says. In the case of one practice a few weeks ago, it meant erasing a fast-break drill.

It's not just the high-usage players that are closely monitored. Someone like redshirt freshman Austin Davis, who has played sparingly in nine of Michigan's 20 games, is encouraged to reach higher a PlayerLoad to make up for the lack of game action. Sometimes he does extra work before or after practice.

"Your conditioning and your strength are perishable qualities," Sanderson says. "If you don't tap into them and maintain them, you lose them."

The players have a feel for their Catapult numbers and sometimes ask about them after practice. Abdur-Rahkman, a senior guard, has been a regular starter since halfway through his freshman season. He says he feels better rested for games now than he did earlier in his career.

"They try to monitor it as much as possible and regulate it, so it helps. When I first got here, two days (before a game), the practices were really hard. Now that day is a little lighter."

PlayerLoad was especially helpful as the Wolverines returned from four off-days around Christmas, a time that also coincided with Wagner's recovery from a foot injury. In addition to doing low-impact cardio workouts -- using a VersaClimber machine and underwater treadmill -- Wagner's PlayerLoad was carefully monitored. The goal was a slow, steady increase.

There is no in-game intervention related to any Catapult data. The point of the technology is to reduce injuries and prepare players to give max effort in actual competition. If Abdur-Rahkman needs to play at least 36 minutes, as he's done in 12 games already this season, and potentially reach a high PlayerLoad to give Michigan the best shot at winning, so be it. The idea is that his output has been managed in the days leading up to the game to allow him to do that.

STRAPPING A DEVICE on a player is useful because, as Wong says, "It's a sensor that's not formulating any subjective judgments." But Wong, along with several others involved with the basketball program's use of Catapult, recognize the data is just part of the equation.

Beilein's receptiveness and fluency with respect to the information are essential.

"His buy-in is tremendous," says Wong. Adds Sanderson: "He trusts the system and the data and can make his own interventions."

"He is in a position to use Catapult in an advantageous way because he aligns it with his intuition," Finholt says. "I think it would be wrong for a coach to sit back and wait for Catapult to tell him what to do."

Beilein's coaching career started with a high school job in 1975, and he's made a stop at nearly every level since -- community college, Division III, Division II, and three Division I schools before he landed at Michigan in 2007. He half-jokes that in his early years, the only information he had was the score of the game.

Now that he has so much more at his disposal, he's making the most of it.

"The only reason I'm still coaching after 43 years is that I continue to embrace change," Beilein says. "I'm not a computer guy or an analytical guy, but I really like to win."