This week’s Training Tip Tuesday covers two common (and confusing!) Garmin metrics: training load and training status. We have all been there: killing our workouts yet still getting the messages of “unproductive” training status from our devices. Seriously, what’s up with that?!
Garmin Training Load feature is based on the measurement (or rather an estimation) of a metric called “Excess Post-Exercise Oxygen Consumption”, also known as “EPOC”. EPOC is a measure of how the metabolic cost of an activity – essentially, how much oxygen your body is consuming after exercise to restore homeostasis. After exercise, oxygen consumption stays elevated for some time to restore homeostasis – to bring down the elevated body temperature, and heart rate; clear metabolites from the system, repair tissue damage, etc. The extent of EPOC depends on the intensity and length of the activity: short and low intensity activities have a smaller EPOC compared to activities that last longer and are moderate-to-hard in intensity.
Rapid and Slow Component of EPOC
EPOC consists of rapid and slow components. During the acute, or fast component of EPOC, your body will consume more oxygen than normally at rest to replenish the phosphagen and oxygen stores. During the slow component of EPOC, your body will consume oxygen above the baseline to bring down increased heart rate, respiration, and body temperature; restore muscle glycogen and phosphagen stores, repair tissue damage, and to clear and recycle any metabolites (e.g. lactate) from the muscles and circulation. The fast component may only last for a couple of minutes, but the slow component may take up to several hours.
How is EPOC Measured?
Directly measuring EPOC can be accomplished by using an indirect calorimetry that measures oxygen consumption and uses the data to estimate metabolic rate. Using this method is often not feasible in everyday life and outside of laboratory settings, and that is why Garmin uses a patented method by Firstbeat to estimate EPOC from heart rate data. In Garmin devices, training load is the sum of EPOC measurements from the past seven days. The devices also compare the weekly training load to the long-term training load, considering the user’s fitness level and showing whether the current training load is optimal.
Garmin Training Load
- High – current training load might be too high to produce positive results
- Optimal – current training load is ideal for maintaining and improving fitness
- Low – current training load is too low for the current fitness level and habits, and will unlikely improve fitness
Things to Keep in Mind
Garmin training load is an estimate of your actual training load and based on an estimate of your EPOC, which is estimated from your heart rate. Because the estimate of your training load is derived from several other estimates, you should not rely on it as a 100% truth. Keep in mind that things like whether or not you enable the measurement of heart rate during activity, and where the heart rate is measured (mainly wrist optical light vs. chest strap – wrist-based heart rate is WAY less accurate compared to the chest strap and may contain a large degree of error) influence the outcome and accuracy of the training load estimate. If you measure your heart rate during some activities, and opt out for others, the training load will not reflect the total training load and only includes the activities where heart rate was measured.
The ‘Training Status’ feature in the Garmin devices tells you how your training influences your fitness level and performance. This metric is calculated based on the changes in your training load and VO2max estimate (see the previous blog post on the Garmin VO2max estimate). Garmin suggests using the training status metric to improve future training so that you “continue improving your fitness level.” (Garmin)
Garmin Training Status
- Peaking – i.e. “the ideal race condition”. This state is achieved after by reducing training load and recovering from the previous sessions.
- Productive – the current training load is sufficient to elicit fitness gains.
- Maintaining – the current training load is enough for maintaining the fitness level, but more variety, volume, or intensity is recommended for improving your fitness.
- Recovery – the current training load is lighter and allowing your body to recovery.
- Unproductive – the training load is at a good level but your fitness is decreasing. You may not be recovering as expected.
- Detraining – the training load has been much less than usual for a week or more, and it is negatively affecting your fitness level.
- Overreaching – the training load is very high and counterproductive; you need to rest!
- No status – New device? Your Garmin needs 1-2 weeks of training history (including activities with VO2max prediction) to determine your training status.
Garmin metrics may be helpful in giving feedback on the training-recovery balance. Caution should be practiced, however, when utilizing these metrics since they are all estimates and therefore, not 100% accurate. The estimates are based on heart rate measurements during the training sessions. Many new devices come with an option of a wrist-based heart rate measurement, which, unfortunately, has been demonstrated to be less accurate than chest-worn heart rate straps. To improve the accuracy of the Garmin metrics estimates of training load and status, one should utilize a chest-worn heart rate strap so that the measurements of heart rate are the closest to the true values. If one chooses to follow the Garmin training load and status and base their training off these readings, heart rate should be measured during each training session to get the most accurate representation of the actual training load.
McArdle, WD, Katch, FI & Katch, VL. Exercise Physiology – Nutrition, Energy, and Human Performance, 8th ed. Baltimore (MD): Wolters Kluwer Health; 2015. p.169-170
Garmin [Internet]. United States [cited April 14, 2021]. What is the training status feature on my Garmin fitness device? Available from: https://support.garmin.com/en-US/?faq=VxKazDQ2mkAmDoQbJriEBA
Garmin [Internet]. United States [cited April 14, 2021]. What is the training load feature on my Garmin device? Available from: https://support.garmin.com/en-US/?faq=SEkNpdGyhR917js0qQL3Q6