How WHOOP Strain Target Works

The WHOOP Strain Target provides activity level recommendations based on your Recovery and shows you in real time how close you are to reaching your goal. To use this feature effectively, you need to understand what Strain is, how it's calculated, and how it connects to your body's preparedness.

This article will break down the fundamentals of WHOOP Strain, explain the science behind the 0-21 scale, and show you how to use the Strain Target to optimize your training and daily performance.

What is WHOOP Strain

WHOOP Strain measures the total cardiovascular load and muscular effort your body experiences throughout the day on a 0-21 scale. It quantifies exertion from all sources — workouts at varying exercise intensities, daily activities, and mental stress. Unlike step counters, Strain provides a precise, personalized measure of how hard your body is working.

Strain is not just about exercise. It captures everything from an intense training session to a stressful meeting, a long walk, or even the physiological impact of illness.

How WHOOP calculates Strain

WHOOP Strain is calculated based on two primary metrics:

1. Cardiovascular strain
2. Muscular strain

Cardiovascular strain is calculated based on the duration you spend in various heart rate zones. The higher your heart rate and the longer it stays elevated, the more Strain you accumulate. WHOOP monitors your heart rate continuously to build an accurate picture of your cardiovascular load.

Muscular strain is calculated from strength training or bodyweight activities, estimating maximum volume and intensity of strength-based workouts.

The scale is logarithmic, meaning it becomes progressively harder to add Strain as your score increases. Building from a 10 to an 11 requires less effort than building from a 20 to a 21. The calculation is personalized to your unique fitness level, ensuring your Strain score reflects your true effort.

Two people doing the same workout may accumulate different amounts of Strain based on their cardiovascular fitness, recovery state, and individual response to exertion. WHOOP accounts for these differences, making your Strain score uniquely yours.

How the Strain Target works

The Strain Target gives you an exertion-level recommendation based on your Recovery and Strain you've already accumulated, helping you determine how often you should work out. When you start an activity, it shows your Strain building in real time towards the suggested goal. You can also see calories burned and your current heart rate zone. This transforms WHOOP from a feedback tool into a real-time coach.

Upgrade your training

The initial recommendation from the Strain Target is based on an optimal state to maintain your fitness level. However, you can adjust your goal depending on your intent. Maybe you're tapering prior to a big event and prefer to train in a restorative state to allow for active recovery, or you'd like to push yourself to make fitness gains with functional overreaching.

The Strain Target tells you how long and hard to work out to meet it — whether to keep pushing or if you're overdoing it. Should you do that extra lap or set of reps? The Strain Target has the answer.

Start optimizing your training

Understanding your Strain is the first step toward smarter training. By using the Strain Target to guide your exertion, you can balance your daily load with your body's readiness to perform. Ready to move from tracking to training? Join WHOOP and start making every day count.

Frequently asked questions about WHOOP Strain

Is high Strain on WHOOP good?

A high Strain score is a tool, not a judgment. On a day with high Recovery, high Strain can help you build fitness. On a day with low Recovery, high Strain may lead to overreaching. The ideal Strain depends on your body's recovery and your goals.

Why is my WHOOP Strain so high on a day I didn't work out?

Strain measures your body's total cardiovascular load, not just exercise. Factors like stress at work, running errands, illness, or a difficult commute can elevate your heart rate and contribute to your Strain score.

How does Strain relate to Recovery?

Strain and Recovery are two core pillars of WHOOP. Recovery measures your body's capacity to take on load, while Strain quantifies the load you take on. The goal is to balance the two—pushing hard when ready and resting when needed.