Below we’ll discuss what exactly our strain metric is, how it’s calculated, the factors that play a role in determining your strain for the entire day and for various activities, the WHOOP averages for each, and the relationship between strain and recovery.
What is a WHOOP strain?
WHOOP exertion is a measure of cardiovascular and muscular exertion that quantifies the amount of physical and mental stress you place on your body. We monitor your stress on a scale of 0-21, both for the whole day and for certain trainings and activities. Inspired Borg’s rating of perceived exertionstrain numbers can be loosely broken down as follows:
WHOOP measures your stress on a scale of 0-21. the higher it is the harder it is to build more.
LIGHT (0-9): Minimal stress on the body, space for active recovery MODERATE (10-13): Moderate stress on the body, generally good for maintaining fitness HIGH (14-17): Increased level of stress and activity, ideal for increasing fitness during training ALL OUT (18-21): Significant stress, often excessive, probably very difficult to recover from the next day Learn more: Why WHOOP doesn’t count steps
What causes strain and how does WHOOP calculate it?
WHOOP measures exertion based on cardiovascular and muscular workload. Cardiovascular is your heart rate, and the higher your HR is and the longer it stays elevated, the more you exert yourself. When you use the Strength Trainer, WHOOP can track your weights, reps and sets to understand the demands you place on your musculoskeletal system. Muscle load measures movement and its underlying physics using the accelerometer and gyroscope sensors in WHOOP and combines these signals with advanced biomechanics and mathematics. This metric includes volume and intensity components.
- Volume is measured similarly to traditional volumetric load, but includes effective mass. It takes your body mass into account, but only includes the parts of your body that move and do work. For example, a full-body exercise such as a squat or lunge will have more muscle load than a bench press.
- Intensity quantifies how much effort or effort you put into completing the lift. This includes the speed of movement and proximity to failure or fatigue profile of the set.
WHOOP then calculates cardiovascular and muscle load of your strength training to get the full strain result. Regular daily activities like work, commuting, running errands and parenting can cause tension. That’s how it can be stress, anxietyexcitement or feeling nervous – even being a sports fan is hard work.
WHOOP calculates your effort for the entire day and for specific periods of exercise or activity. Learn more: Frequently Asked Questions about the WHOOP strain
Activity strain vs. Dan Strain
When WHOOP notices a spike in heart rate and movement over a longer period of time, it will automatically detect your activity or exercise and give you a load value for it (you can also manually add other activities and see their load). Your total daily effort gives you additional insight into the cardiovascular load your body takes outside of exercise. For example, a presentation at work or a busy afternoon with the kids could increase your daily effort above average, even on a non-exercise day.
WHOOP detects your workouts and tells you how hard they are. YOUR daily effort is not the sum of your activities.
If you have more training in a day, the effort of your activities it does not contribute to your total daily effort. The WHOOP strain algorithm is logarithmic, meaning that the higher your strain, the harder it becomes to build more. As illustrated in the graphic above, it is much easier to go from 0 to 10 exertion than from 10 to 20. Hypothetically, running a marathon might raise your daily exertion to 20.4 or 20.5, but then run another that day could only increase to 20.6 or 20.7. Learn more: Stress Science Podcast with Dr. Andy Walshe
What is a “normal” amount of stress?
Strain average for all WHOOP members is nearby 11.0 per day. It is no surprise that this number has been decreasing over the years. Below you can see the daily average of strains by age and gender:
Average daily tension for WHOOP members is around 11.0, decreasing with age.
When it comes to individual trainings, more intense aerobic exercises leads to greater strain than less intense activity. Average strain for 1 hour from running is about 12.0while an hour from walking is about 6.5. Average strain for 1 hour from functional readiness is 10.1.* *Note that this data does not include strain results from activities like weight lifting, which will now be possible with the Strength Trainer. Learn more: Average effort of the 10 most popular activities
Strain is highly individualized
Strain is calculated from your personal HR metrics and accounts for your individual fitness level. Because it quantifies how hard your body is working, not what your body is doing, two people who complete the same activity can have very different types. For example, a 90-minute hike that scores a 10 or 11 for the average person might only be a 5 or 6 for a highly fit athlete. In the same line as yours if fitness improves, you’ll start to see lighter loads for that same activity. Learn more: Quantifying NFL football tension using Patrick Mahomes’ WHOOP data
Stress and recovery
The higher yours recovery the greater the effort your body is ready to take.
The amount of stress your body is prepared to take depends on your recovery each day.
You may notice that tension builds up more quickly on days when you have low recovery, because your body is not sufficiently prepared for it. A workout routine that usually gets you a 9.5 can be a 10.5 when you’re in the red. Your Stray’s coach suggests the optimal amount you should take each day based on your recovery. This is the recommended level of effort intended to maintain fitness and adequate recovery the next day.
Your Weekly performance reviews show a balance between your effort and recovery. If you go above this amount, you’re “overdoing it” (good for improving fitness, but probably detrimental to your recovery the next day), and if you stay below that, you’re “recovering.” On the other hand, the amount of stress you take on today affects how you recover tomorrow. Learn more: Understanding the WHOOP strain podcast