EPOC (excess post-exercise oxygen consumption)
EPOC Based on Heart Rate
EPOC (excess post-exercise oxygen consumption) prediction based on heart rate (HR) measurement. EPOC is basically the excess oxygen consumed during recovery from exercise as compared to resting oxygen consumption. The EPOC prediction method has been developed to provide a physiology-based measure for training load assessment.
Training load assessment
There is no such thing as universal optimal exercise dose. It is different with different people. Sufficiently strenuous exercise causes a disturbance in body’s homeostasis which after recovery results in improved fitness. Too easy training does not improve fitness but long-term hard training may lead to overtraining. This is a particularly unwanted effect with professional athletes. Overtraining may become apparent when it is too late, e.g. during tournaments, championships, etc. It is therefore important to measure the training load.
Methods that are used in assessing training load may be broadly defined as subjective and physiological measures. Subjective measures are easy to access, but do not always reflect physiological responses and recovery demand. Traditional physiological measures (like oxygen consumption (VO2), heart rate and blood lactate) reflect mainly momentary intensity of exercise and not the length of exercise or the cumulative exercise load. There are other training load indicators (E.g. training impulse (TRIMP)), but most do not have physiological basis or scale and therefore may be difficult to interpret.
EPOC is a physiological measure (amount of oxygen consumed in excess after exercise as measured in liters or ml/kg) that that reflects the recovery demand and the disturbance of body’s homeostasis brought by the exercise. Measurement of EPOC is achieved by analyzing respiratory gases with specialized laboratory equipment, which makes it expensive, time consuming and not applicable to practical sports purposes.
This lack of valid and easy-to-apply physiology based method for the assessment of training load has led us to
This is when we developed a method to estimate EPOC indirectly from heart rate measurement. This method is a valid and easily applicable physiology based method for the assessment of the training load of a physical exercise session.
EPOC in physical exercise sciences
The first observation of an elevated resting metabolic rate after exercise was made as early as 1910. The modern name EPOC has been used not only to represent oxygen repayment during recovery, but also to reflect the general exercise-induced disturbance of body’s resting metabolism and homeostasis.
Basically EPOC reflects the body’s requirement for recovery after physical exercise. Active oxygen-consuming recovery processes occurring in the body are due to replenishment of body’s resources (O2-stores, ATP, CP) and increased metabolic rate (increased HR and respiratory work, elevated body temperature) caused by metabolic by-products and hormones produced during exercise.
Some EPOC science facts
EPOC reflects the general disturbance in the human body’s homeostasis caused by physical exercise.
EPOC is calculated by subtracting the area under resting VO2 from the area under the recovery VO2 curve.
EPOC gets higher with higher intensity and/or longer duration of exercise.
Construction of the Model for Heart Rate Based EPOC Prediction
The EPOC model was constructed based on meta-analysis data of peer-reviewed articles. Only valid studies were carefully selected for this purpose. The data included 48 different exercise settings, including a total of 158 trained and untrained male and female subjects. Exercise durations ranged from 2 to 180 minutes and exercise intensities from 18 to 108% of VO2max. The modeling data included both continuous and intermittent exercises and consisted of running, cycling and upper-body ergometer exercise.
EPOC is predicted only on the basis of heart rate derived information. The variables used in the estimation are current intensity (%VO2max) and duration of exercise (time between two sampling points, dt) and EPOC in the previous sampling point. The model is able to predict the amount of EPOC at any given moment. No post-exercise measurement is needed. The model can be mathematically described as follows:
EPOC (t) = f(EPOC(t-1), exercise_intensity(t), dt).
At low exercise intensity (<30-40%VO2max), EPOC does not accumulate significantly after the initial increase at the beginning of exercise. At higher exercise intensities (>50%VO2max), EPOC accumulates continuously. The slope of accumulation gets steeper with increasing intensity.
EPOC as a Measure
EPOC is a physiological measure for training load
Working out with a low overall training load does not improve fitness condition and shape. On the other hand, too much load may lead to overtraining over time. Therefore it is important to measure your training load.
EPOC is basically the excess oxygen consumed during recovery from exercise as compared to resting oxygen consumption. It is a physiological measure of training load. The amount of EPOC achieved during each exercise is proportional to the training load and recovery required.
EPOC is perfect for training:
• The more you exercise in terms of intensity and duration, the higher is the build-up of EPOC
• Virtually applicable to any exercise at all. Intensity level may vary during the training session; breaks are allowed and everything will be taken into account.
• EPOC indicates the effects of the entire training session.
• Current physiological state is directly reflected in EPOC accumulation: if one is not recovered from the previous exercise – this will result in higher EPOC.
Traditionally, EPOC is measured only after the exercise as the excess oxygen consumption during the period of recovery. See figure above. To make an accurate measurement, you need expensive equipment for breathing gas analysis under controlled laboratory environment. Now EPOC can be accurately and reliably pre-predicted based on just the measurement of heart beat data during exercise, and not requiring any monitoring at all of the recovery period. Experiments have shown correlation of 0.89 between measured and pre-predicted EPOC. Read more about validity from our EPOC white paper.
EPOC has several advantages as a measure of training load:
• An objective, physiology-based and scaled measurement method
• Scientifically validated method, based on laboratory studies
• Scientifically acknowledged to be better than lactate
• The heart beat data collection and analysis based on method is non-invasive, and is designed for your comfort and safety
|
 |
|
|
