On a recent cold February Sunday afternoon I was a center referee for a U18 girl’s Development Academy showcase game. I have worn a Garmin Forerunner 235 watch for the past couple of weeks but this game was my first time using this watch for an entire game. I want to share with you some insights from the numerous data points collected during this 90 minute game.
Disclaimer- I am a collegiate strength and conditioning coach. I have a lot of experience with heart rate monitoring, fitness testing and GPS based technologies.
If you do utilize GPS watches during workouts I believe you should have a reason for collecting data. If it is just for the sake of curiosity then I suggest you stop reading this post now. If you currently are or would like to collect data to make informed decisions regarding training, preparation and injury prevention then I’m hoping this post will have a couple of key takeaways for you.
Most GPS and wrist heart rate watches will continually collect data throughout the day. Simple measures may include a daily step count, average resting heart rate, maximum heart rate and total distance covered during a single 24 hour period.
I had four game assignments on Sunday. I was an assistant referee for three games and was a center referee for the U18 game referenced above. All of these games ranged from U16 to U18.
The game itself consisted of two possession minded teams and made for a competitive encounter. This was my first game a center referee for almost two months as the last game I worked was during the Thanksgiving break.
According to my watch I ran 2.55 miles in the first half. This was a tournament game which meant no additional time during each half. However, I did forget to stop my watch for 24 seconds after I blew the whistle for half-time. This would marginally affect my average pace per mile but I don’t want to get too caught up on that today.
I pride myself on being an “active” referee in that I like to move around the field and keep up with play. Depending on the level of games you work this might be a rarity among fellow referees. Because of this my total distance may be higher than some other referees that use GPS watches for their games.
The online software for my watch (Garmin Connect) provides a map of my movement during the first 45 minutes of the game.
I’m not convinced that the map above provides any meaningful value. What the map doesn’t account for is the flow of the game, standard of teams and surface of the field. All these factors will influence a referee’s positioning on the field. However, if you look at many maps over lots of different games worked- I suggest at least 20+ (age, gender, field surface, and standard) you might be able to notice a pattern: perhaps you notice that it looks like you favor one side of the field a little too much…or you notice that you are not covering as much of the field as you thought you were. Only then will these maps provide value.
During the second half I ran 2.52 miles. Again I forgot to stop my GPS watch- over time I’m sure I’ll get in the habit of doing so.
Elevation, pace and heart rate
Unless you live in a high altitude or frequently travel out of state to work games at high altitude the elevation data does not contain any real value. As a general rule resting heart rate and exercise heart rate will gradually increase at higher altitudes.
Pace and heart rate will be dictated through the demands of the game. These numbers will typically be inversed. A lower pace as measured in minutes and seconds will result in faster runs and therefore a higher heart rate throughout a game.
My average mile pace in the second half was 18 minutes and 27 seconds. That is less than 3 miles per hour- which would be considered by most to be a brisk walk.
My average heart rate in the second half was 134 beats per minute. The majority of watches will automatically calculate maximum heart rate and relate average heart rate in terms of difficulty but if you wish to do so the simplest formula is:
220 minus age
Example: 220 – (26 years old) = 194 beats per minute
I typically think of 200 as my maximum heart rate (yes- I’m rounding up a little) so my perceived level of difficulty in the game was 134 beats divided by 200- the sum of which equals .67 or 67% difficult. Which does seem correct- I would not describe the game as being strenuous.
Heart Rate Zones
Perhaps the greatest and most useful set of data points is found within the “time in Zones”. The time in zones calculates how much time you spent within a certain heart rate range during each half or full game. See my heart rate zones for the first and second half below.
Heart rate zones are determined through a percentage of maximum heart rate. Zone 1 is approximately 50-59% of maximum heart rate while zone 5 is considered 90% and above.
If you do not have access to a heart rate monitor these zones can be estimated based on perceived exertion or difficulty out of 10. The closer your number creeps towards 10 (or zone 5) the harder your body has to work in order to keep up with the demands of the game.
So what does this all tell me?
It tells you how to train
If I want to train for U18 Development Academy game I know that my body needs to be prepared to cover more than five miles in 90 minutes at an average difficulty of 67% of maximum heart rate or a 6.5 out of 10 level of difficulty.
I know that for about 40% of an entire 90 minute game my heart rate will be between 117-137 beats per minute—the same can be said for 40% of an entire 90 minute game at 137-156 beats per minute.
I know that I only spend about 5% of an entire game duration at 176 beats (Zone 4&5) per minute or above.
Do I really need to train for 90 minutes to prepare for a single game?
Occasionally, yes- but rarely. Let’s do some math:
40% of 90 minutes = 36 minutes
5% of 90 minutes = 4.5 minutes
I now know that about 36 minutes of a game is placed at a brisk walk—or a similar heart rate response to a brisk walk. Do I really need to train for this? With an average level of fitness and an active lifestyle I would suggest probably not.
To meet the demands of a game I should run at a difficulty level of 6.5 out of 10 for approximately 30-40 minutes.
I should also run VERY HARD for a total time of about 4 and half minutes. I suggest that these runs match the demands of a game- think of 60-80 yards sprints to mimic a classic counter attack.
I was surprised to learn that I had over 33,000 steps over the course of four games. Up until then my average was somewhere between 12 and 16,000 steps per day. If I do happen to take another a break from soccer tournaments or multi-game days I know that for my feet not to hurt I should build up to about 30,000 steps of walking over a period of 1-2 days.
What else can a heart rate GPS watch tell me?
If you are serious about your training and recovery between games most watches will have the option of sleep and resting heart rate tracking. A higher than normal resting heart rate over a number of days could mean overtraining or perhaps even a forthcoming potential sickness.
As always, take caution with using few days or few data points to form a conclusion. Take numerous measurements and record numbers for multiple games before adjusting your training plan or referee availability.