Soccer is a high intensity sport that places significant demands physically and technically on athletes. Successful players must have a high aerobic capacity as well as the ability to perform repeated high-intensity movements. During the course of a game, heart rate (HR) values fluctuate between 60-75% of maximal HR (HRmax) to upwards of 80-90% HRmax 1,2. Athletes who consistently maintain such a high percentage of HRmax during the course of a game will begin to show signs of fatigue. Therefore, fitness training needs to be similar to conditions experienced during a game and use of HR monitoring can assist coaches and players in better understanding how to match training to game play.
The ability to monitor heart rate during game play and practice sessions was once out of reach. With technology from Polar, athletes and coaches can view their heart rates in real-time using Polar Team2 System via Bluetooth communication. The Team2 system also continuously records data that can be downloaded and further analyzed to better manage recovery among athletes. Traditionally, heart rates are monitored to assess fitness levels. Monitoring and managing training intensities are important for practice sessions in an effort to better prepare athletes for game play. Improving cardiovascular endurance can be achieved while also working on technical and tactical aspects of the game.
Figure 1. Polar Team2 System
Polar Team2 System makes it easy for coaches and athletes to recognize and understand training intensities. Sport Zones are color coded for the different intensities, which are based on individual percentages of Maximal Heart Rate (MHR). The zones include:
- Very Light (grey; 50-59%)
- Light (blue; 60-69%)
- Moderate (green; 70-79%)
- Hard (orange; 80-89%)
- Maximum (red; 90-100%)
Not only does the system indicate what zone athletes are in, but it also calculates the amount of time and percentage of time in each of the zones. Coaches can examine the amount of time spent in the zones during the first half verse the second half; are the athletes maintaining the same intensity levels throughout the game? Are there consistent intensity levels from the player from game to game over the season? Let's take a look...
Figure 2. Heart rate tracking across the first and second half of a soccer match
Figure 3. Time spent across heart rate zones during a soccer match
Having the ability to examine physiological changes through heart rate monitoring allows coaches to either confirm or disprove their instincts and reflections of the game as well as the overall season. For example, the first and last 10 minutes of each half are critical moments that can determine the outcome of the game. Thus, is there a significant difference among players' intensity levels during games that resulted in a goal against during the first and last 10 minutes of each half and those games that did not? Or is this more psychological in nature? Let's take a look...
Figure 4. Individual HR Curve when no goal scored in first 10 minutes of a half
Figure 5. Corresponding values when goal no scored in first 10 minutes of a half
Figure 6. Individual HR Curve when goal scored in first 10 minutes of a half
Figure 7. Corresponding values when goal scored in first 10 minutes of a half
While the Team2 system provides a powerful means of assessing a soccer teams heart rate response to training, some of these assessments can easily be done individually among athletes with a heart rate monitor and watch. In part two of this article, we will explore various training methods using heart rate monitoring with either the Team2 system or an individual heart rate monitor and watch. Additionally, data from individual monitors can be synchronized to numerous software applications that can provide similar summary graphs of heart rate over time such as trainingpeaks.com, polarpersonaltrainer.com, Polar Beat (smartphone application), RunKeeper, etc.
Kimberly Kostelis is an associate professor and department chair in the Department of Physical Education and Human Performance at Central Connecticut State University. Kim teaches graduate and undergraduate courses including Research Methods and Measurement and Evaluation in Exercise Science. Kim received her undergraduate degree from McDaniel College, Westminster, MD and completed both her masters and doctorate at Springfield College, Springfield, MA.
Jason Melnyk is an assistant professor in the Department of Physical Education and Human Performance at Central Connecticut State University. Jason teaches graduate and undergraduate courses including Advanced Exercise Physiology, Theories of Strength & Conditioning, and Training for Sports Performance. Jason received his undergraduate degree in exercise physiology from the University of Delaware and completed his masters at the University of Maryland. He holds a doctorate in muscle physiology from Virginia Tech. Jason is also a certified strength and conditioning specialist with 10 years of personal training experience.