The intensity at which an athlete performs training exercises is a crucial factor in athletic training and development. However, it is often difficult to accurately quantify how intensely an exercise has been performed. This can be an obstacle in planning effective training sessions as certain exercises must be performed at prescribed intensities in order for there to be the desired degree of athletic improvement. Performing an exercise at too low of an intensity will not allow the athlete to progress and, over the long term, will result in stagnation or a degradation of athletic ability. Performing an exercise at too high of an intensity can result in excessive fatigue, injury, or overtraining.
Training intensity can be accurately determined by the amount of oxygen one uses in one minute of exercising per pound of bodyweight. This value is known as maximum oxygen consumption, aerobic capacity, or simply VO2max. Unfortunately, finding your VO2max requires expensive equipment, a controlled laboratory environment, and trained technicians. Elite athletes often have clinical tests done in order to determine their VO2max. These types of test are only available to those elite athletes with financial support and the required clinical resources. However, extensive research has shown that it is possible to accurately estimate your exercise intensity as a percentage of VO2max from your heart rate. This is possible because of the linear relationship between heart rate and oxygen use. Obviously, it is impractical to attempt to measure your heart rate during intense activity by pressing fingers against an artery and counting the number of beats in a set period of time. Heart rate monitors provide the perfect solution to the problem of accurately monitoring the heart rate without interrupting the exercise.
Zones of intensity are represented by the percent of the maximum oxygen consumption, or %VO2max, and then related to the percent of the maximum heart rate, or %HRmax. Current research has found that the previous measurements relating the %VO2max to %HRmax, as recommended by the American college of Sports Medicine (ACSM), underestimated heart rate by up to 15%. New %HRmax values have been implemented which more accurately reflect intensity in the training zones.
Heart rate monitors (HRM) can be used in several different ways to improve the effectiveness and efficiency of training. The main applications for soccer training are
|Monitor the intensity during training exercises:
|Calibrate the intensity of training exercises:
|Help identify and prevent overtraining|
|Quantify microcycle and macrocycle training intensity|
|Monitor changes in physiological variables during the season|
|Increase motivation and awareness of sports-related physiology|
Monitor the intensity during training exercises
Conditioning exercises (running, swimming, cycling, etc.) can be prescribed according to the energy system in which they utilize. This is referred to as training the energy systems. Five energy systems have been identified based on the duration and intensity of the exercise. Determining the conditioning exercise requirements based on the energy system to be utilized is an extremely effective and efficient means for a coach to focus on a specific element of an athletes conditioning based on its relevance to the particular sport.
The following table describes the five energy systems and their training characteristics including percent heart rate reserve. Heart rate reserve (HRR) is the difference between the resting heart rate and maximum heart rate and has been found to be a more reliable predictor of intensity.
|Type of Training||%HRR
|Duration of reps||Number of reps||Rest interval||Ratio work:RI|
|Lactic acid tolerance training (LATT)||>85
|30 – 60 sec||2 x 2 – 4||10 – 15 min||1:10 – 1:15|
|2 – 2.5 min||4 – 6 (8)||>5 min|
|Maximum oxygen consumption training (Max VO2)||80-100
|3 – 5 min||4 – 8 (12)||2 – 3 min||2:1|
|Anaerobic threshold training (AnTT)||60 – 84
(70 – 89)
|1.5 – 7 min||3 – 5||5 min||1:1|
|8 – 120 min||6 – 2||5 – 45 min||1:6 – 1:15|
|Phosphate system training (PST)||NA||4 – 15 sec||10 – 30||1 – 3 sec||1:4 – 1:25|
|Aerobic threshold training (ATT)||45 – 59
(59 – 69)
|10 – 120 min||6 – 1||1 – 2 min||1:1 – 1:25|
As the table indicates, with the exception of the phosphate system which is only activated during short sprints, the percent of heart rate reserve measured during training is an accurate indicator of the energy system being used.
Soccer is categorized as an intense intermittent activity, meaning that the game involves continuous jogging with brief periods of sprinting short to medium distances while changing directions, jumping, quick accelerations and decelerations, and kicking. From this analysis, we can see that soccer requires aerobic, anaerobic, and power conditioning. In particular, recent research has indicated that that aerobic capacity (VO2max) plays a key role in determining a players’ fitness and ability during a soccer match.
The minimum training intensity for improvement in VO2max and the lactate threshold is approximately 40-50% of HRR. Swain has found that the minimum exercise intensity for improvement of VO2max is 45% of HRR.
“The ACSM now recommends relating HRR to VO2R rather than a percentage of VO2max. Using VO2R improves the accuracy of the relationship. The ACSM has also increased the estimated difference between the % VO2R (%HRR) to the %HRmax from 10% to 15% difference. This is based on research from that show that the HRmax method actually underestimates the VO2R by approximately 15%. The underestimation may be larger or smaller depending on age and intensity of exercise.”
Heart rate reserve, and therefore heart rate monitors, can also be used to accurately estimate the relative intensity of the training. In addition, because heart rate is linearly related to aerobic capacity (VO2max), HRMs can be used to monitor the intensity of training as a percentage of your total aerobic capacity. Training intensities are typically divided into different zones which correspond to levels of activity. According to the latest ACSM position stand (1998):
|Intensity||Endurance-type activity (relative intensity)|
|%HRR or %VO2R||%HRmax||Borg RPE|
|Light||20 – 39||35 – 54||10-11|
|Moderate||40 – 59*||55 – 69||12-13|
|Hard||60 – 84||70 – 89||14-16|
VO2R (reserve VO2 ) = VO2max – resting VO2;
Monitor training intensity during tactical exercises
The principle of training the energy systems can be combined with tactical exercises in order to make training more economical. Tactical drills are organized according to intensity, duration, and work-to-rest ratio to allow the athlete to combine soccer-specific tactical training with conditioning exercises. Heart rate monitors can be used to make sure that players are staying within the prescribed zones of intensity during periods of work and rest and thus getting the maximum benefit from the training.
Monitor recovery training
A crucial element to training is recovery. The only time the body adapts to new training stimuli and improves is during periods of rest. Low-intensity training at 45 – 59%HRR, especially following a day of high-intensity work or competition, can aid in removing toxins (lactic acid, etc) from the body. HRMs can be used to ensure that athletes adhere to proper heart rate ranges in order to maximize recovery and prevent overtraining or injury.
Monitor and calibrate intensity during warm-up
Proper warm-up before training or competition is essential if athletes are to prevent muscle tears and strains. The key to a proper warm-up is to elevate the heart rate sufficiently to allow blood flow to all of the muscles of the body. HRMs can accurately indicate when such a heart rate has been achieved, thus allowing the athlete to reach the proper warmed-up state in the least amount of time.
Often a coach will design a warm-up routine with the aim of properly preparing a team for competition or training. A heart rate monitor can be used during the planning stage to determine the proper duration and intensity for each of the various activities in the warm-up routine.
Calibrate the intensity of training exercises
By using heart rate monitors during tactical drills, a coach can determine what the average training intensity is during the work period of the exercise, what an appropriate work-to-rest ratio should be based on the energy system and heart rate decrease, and the duration of the drill for maximum effectiveness. Knowing the average heart rate during a drill allows the coach to determine which energy system is predominate and, thus, prescribe when and how often the individual tactical exercise should be used.
Help identify and prevent overtraining
Overtraining occurs when an athlete has been over-stressed and is no longer able to perform at previous athletic levels. Overtraining is characterized by a degradation in athletic ability and may be caused by many factors, not all related to training. One of the earlier symptoms of a overtraining is a variation in heart rate. Current research indicates that an athletes resting heart rate (measured immediately after waking in the morning) will rise during periods of overtraining, and will take longer than normal to recover to normal levels during strenuous activity.
According to one source, one means of identifying an early indication of overtraining is to check the resting heart rate in the morning while still lying and bed. If the RHR is within ±3 BPM from previous measurements then it is acceptable to continue with training for that day. If the RHR has risen by up to 5 BPM then only light training should be undertaken, and if the RHR has risen by 10 or more BPM then no training should occur and a day of rest scheduled, instead.
Another source reports that a difference of 8 or more BPM between the RHR measured when supine (laying down) and the RHR while standing is an indication of the onset of overtraining. In which case, training should be light or canceled.
Quantify microcycle and macrocycle training intensity
Training intensity can be modulated weekly and monthly in order to maximize overcompensation and adaptation to training. This means that high-intensity, medium-intensity, and low-intensity days are scheduled according to the schedule of athletic events/meets so that the athlete is at a peak for competition. HRMs can be used to quantify the intensity of daily training by using the following equation:
(average workout HR) – (RHR)
Intensity Value = ´ (total training time [min.])
(HRmax) – (RHR)
For example, during a 90 minutes training session, an athletes average heart rate was 165 bpm. His resting heart rate on that day was 70 bpm, while his maximum heart rate (determined through field testing) was 200 bpm. The intensity rating value for this session was, therefore, equal to 65.7. As a reference point, the maximum possible training value for a 90 minute training session would be 90 (when the average workout HR is equal to the maximum HR).
Measure changes in physiological variables during the course of a season
Certain physiological variables are valuable as a gauge of improvement and as predictors of stagnation or overtraining. As shown above, heart rate reserve is a crucial factor in determining the proper intensity of training. Since maximum heart rate will not change over the course of a season, it is only a function of age, the measurement of resting heart rate is important as it can be used to show the positive or negative effects of training.
Without the use of clinical testing methods, an athletes’ heart rate reserve (HRR) is a much easier value to determine than VO2R and much more accurate than %HRmax. The resting heart rate can be determined simply by counting the number of heart beats in one minute in the morning immediately after waking and before leaving the bed. Although there are several ways to estimate your maximum heart rate, the most common being HRmax = 220 – age, they typically result in large errors. The simplest and most accurate way to determine the maximum heart rate is to have the athletes run continuously at a progressively increasing pace around a field and record the maximum heart rate reached during the run. A heart rate monitor is perfect for this type of test.
Increase awareness of basic sports-related physiology and increase motivation for training
Finally, HRMs can make the student-athlete aware of the basic underlying physiological principles that are crucial to basic health, proper training, and athletic improvement. In addition, HRMs can make working out more enjoyable because so much guesswork is removed and real progress can be made in ability.
Recent research has found that dramatic improvements in on-field soccer performance can be realized by increasing a players aerobic capacity, VO2max.
Before training with a HRM, measurements must be undertaken to determine the initial condition of the athlete. The following field tests are simple and accurate.
1. Maximum heart rate: (Bangsbo or Balsom field test)
2. Resting heart rate: For five consecutive days measure the heart rate immediately upon waking in the morning while still laying in bed. Average the five results to determine the value for resting heart rate (RHR).
3. Heart rate reserve: Calculate heart rate reserve, HRR = HRmax – RHR
4. Maximum oxygen consumption (VO2max): (use field tests to predict VO2max)
5. Determine the speed corresponding to the maximal rate of oxygen use (vVO2max ): Run as hard as possible for six minutes and record the distance covered. Calculate your velocity in feet/second (or meters/sec) to determine your vVO2max. It is recommended that the test be repeated in 48 hours and the highest speed be used as vVO2max.
HR upper limit = 59%HRR (69%HRmax)
HR lower limit = 45%HRR (59%HRmax)
Duration: 10 – 120 min.
Reps: 6 – 1 (i.e. 6×10 min. up to 1×120 min.)
Rest interval between sets: 1 – 2 min.
HR lower limit = 45%HRR (59%HRmax)
(HR should gradually be increased as the warm-up continues)
Duration: 15-20 min.
HR upper limit = 59%HRR (69%HRmax)
(HR should gradually decrease as the cool-down continues)
duration: 5-10 min.
Interval Training Exercises
a) 4 X 4
Run 4 sets of 4 min. at 85-95%HRR (90-95%HRmax) with 3 min. recovery jog at 35-70%HRR between sets.
Frequency: 2X/week for 8 weeks in late pre-season
Run 15 sec. at 72-100%HRR (80-100%HRmax), recover for 15 sec. at 25-47%HRR (40-60%HRmax). Continue until cannot maintain intensity of run.
c) Fixed time intervals
|Run 30 sec at 85-100%HRR||jog 30 sec.|
|Run 2 min. at 80-95%HRR||jog 1 min.|
|Run 4 min. at 73-90%HRR||jog 1 min.|
Run for 30 sec. at 100% vVO2max then recover for 30 sec. at 50% vVO2max
Repeat cycle until 30 sec. at 100% not sustainable
(This exercise is excellent for treadmill running, especially in the early pre-season)
- Increase to 60-60 using same principles
- Increase to 3 min. run with 3 min. recovery using same principles