Kinesiology researchers study elite soccer player for clues to optimal training strategy
While much kinesiology research is conducted in labs, on treadmills, in highly controlled settings, the opportunity to study an extraordinary athlete on the playing field can yield some novel results. The School of Public Health’s Dr. James Hagberg and colleagues had the good fortune of studying a two-season winner of the MAC Hermann Trophy—the top player in National Collegiate Athletic Association (NCAA) division I soccer. The player (referred to as “Player A”) now plays professionally with the D.C. United soccer club, and the data that researchers collected while he played for the University of Maryland’s soccer team became the basis of a new publication in the October issue of the Journal of Strength and Conditioning Research.
The purpose of this study, "Laboratory and Match Physiological Data from an Elite Male Collegiate Soccer Athlete," was to investigate the intensity of Player A’s performance on the soccer pitch in multiple games over the course of two seasons and to compare it to his teammates to explore what factors may influence his success.
As anyone who has ever watched soccer will know, matches are aerobically strenuous, with low-intensity walking and running interspersed with moments of high-intensity sprinting, sliding, jumping and short bursts of acceleration. “Thus, moments of high-intensity exercise contribute greatly to the physiological load of players, while they also tend to take place during important and decisive moments of matches,” the study reads.
For this study, researchers compared physiological data from Player A to those of his teammates over two seasons. They measured maximal oxygen consumption and heart rate during competitive matches, and used the “Polar Training Loads” method to analyze the data. The measure of Polar Training Loads is an individualized method that incorporates body weight, sex, maximal oxygen consumption, heart rate ranges and thresholds to quantify the workload of an exercise session. Researchers suggest this may be a more appropriate measure of load in soccer training and matches than methods used in previous studies.
Comparing one individual player (Player A) to the other team players over the course of two seasons made the data challenging to analyze, said Logan Aronhalt, a graduate student who worked under the direction of Professor Hagberg in the Department of Kinesiology to organize and analyze the data for the project. (The study’s first author, graduate student Ryan Sapp, put the study into its final form after Aronhalt graduated from UMD.) “We had to do separate comparisons game by game, to account for the fact that the one player was facing a different group of team players each game,” Aronhalt said.
The researchers found that Player A had a lower and similar level of maximal oxygen consumption than the team average for the two seasons analyzed. During matches, Player A showed a consistent and significantly smaller amount of time spent at 90–100% of maximal heart rate compared to his teammates. This led to a consistently lower Polar Training Load per minute accumulated by player A as compared to the rest of the team—which may be beneficial over a season and may be related to his success.
This ability to regulate moments of maximal exertion is useful in reducing training load and may be a characteristic of elite players, but researchers acknowledge that they do not know whether their findings relate to differences in the playing style, position, or aerobic capacity of player A.
“As a player, managing your resources is an important skill,” Aronhalt said, referring to his own past experience as a University of Maryland basketball player and a professional player in Italy. “You can’t have both 100% effort all the time and a burst of effort at the right moment.
It’s interesting to pick apart what coaches tell you to do versus what actually happens out there on the field.”
Dr. Hagberg explains that since Player A spends less time maximally exerting himself, “he’s causing less physiological and orthopedic stress. Maybe that’s learned behavior or maybe he can read the game better. By not working in that really high zone, Player A is potentially less likely to be injured, he’s potentially more likely to stay with a long season of games, and he doesn’t get worn down as fast,” Dr. Hagberg says. “If he’s not expending quite as much as other people, that can be big savings by the end of the season.”
Substantial research has been done to track the average physiological load of athletes in training sessions or over the course of a season, but much less information is available about intensity during competitive matches. Dr. Hagberg says this is important, since a match may contribute as much as 25% of the weekly training load, or even as much as half, when two matches are played in a single week. This study is also unique in that it is the first, to Dr. Hagberg’s knowledge, to focus on a single elite player as compared with his team.
“With this study, we measured another skill that contributes to performance,” Aronhalt says. “We showcased Player A’s biggest strength: he’s efficient with his energy. He would know when to turn it on in games. He would appear to be taking it easy, then suddenly he sees an opening and he’s off to the races.”