How GPS Works In American Football
To a sport scientist, a football game is comprised of a series of repeated short duration (4-6 second) but high-intensity efforts with a typical recovery time between plays of 25 to 40 seconds.
Understanding the average time per play, average rest between plays, number of plays per series, rest time between series and total number of plays per game allows coaches insight into the physiological demands of the game. However, these simple stats do not provide specifics about the speed, distance and intensity of certain motions and movements of a player – e.g., standing, walking, jogging, running, sprinting, impacts, etc – during each play and over the course of a game. This sort of data would definitely provide more precise information about the game demands and help coaches better prepare players physically.
GPS technology such as the SPT2 provides this type of information. Currently, most NFL and major college football programs along with some high schools are utilizing GPS to monitor the physical demands of practice and games. However, compared to soccer and rugby, there are few published reports that quantify game demands and movement characteristics in American football.
A research article by former University of Michigan and current New York Giants strength and conditioning coach Aaron Wellman and colleagues monitored 33 NCAA Division I players during 12 regular season games (Journal of Strength and Conditioning Research, Sept 2015).
As would probably be expected, they found significant differences between offensive and defensive positional groups, with receivers and defensive backs completing significantly greater total distance, high-intensity running, sprint distance and high intensity acceleration (positive and negative) efforts than other positions.
These total distances reached ranges of 3295 yards (defensive tackle) to 6050 yards (wide receiver), including up to 720 yards of high intensity running with the high intensity portion – about 5 to 20 percent – made up of approximately 10 sprints and 100 accelerations depending on position.
Here are just a few of the average movement profiles by selected positions. For complete results please refer to the published paper.
|Wide Receiver||Running Back||Defensive Back||Linebacker|
|Total distance (yds)||6047||3433||5135||4533|
|High intensity distance (yds)||716||331||562||475|
|Average max speed (mph)||19.6||17.9||19.3||18.4|
|Number of sprints||13||5||11||8|
Wellman and colleagues also separately analysed the intensity, number and distribution of impact forces experienced by players during competition (Journal of Strength and Conditioning Research, May 2016). Within the offensive groups, WR’s sustained more 5-6.5 G force impacts (moderate to light) than other position groups, whereas QB’s and RB’s were found to endure the most severe (>10 G force) impacts. DB’s and LB’s absorbed more very light (5.0-6.0 G force) impacts, and defensive tackles reported significantly more heavy and very heavy (7.1-10 G force) impacts than other defensive positions.
The added information, beyond number of plays and time per play, etc., provides context to the actual demands during a game and can further aid in the development of conditioning programs and practices. In addition, this information becomes important in monitoring the weekly training load so that players are well-conditioned and remain injury free and fresh for game day throughout the season.