When you think endurance, you might picture a long-distance runner who can slog for miles on end. And while the two go hand in hand, endurance actually applies to more than just your heart's ability to keep you going through a tough cardio workout. So, what is endurance then?
Short answer: It's your body's ability to produce force over long periods of time, says Dr. Rick Richey, DHSc, MS, a trainer at Everlast and the owner and founder of New York City's Independent Training Spot. This applies to your cardiorespiratory stamina as well as your muscles' ability to hold up to challenging workouts, he adds. And anybody, not just runners, can benefit from it.
Below, fitness experts explain how endurance works, how you can build and maintain it, and how to monitor your endurance over time.
Meet the Expert
What Is Endurance?
Put simply, endurance is your body’s tolerance for physical activity before it exhausts, according to NASM-certified personal trainer Sam Goss. And the two major forms of endurance are cardiorespiratory (looking at you, runners) and muscular (hello, weightlifters!).
"While someone may be able to run for miles, if you ask that same person to demonstrate a push-up, you might find them struggling to press themselves off the ground," Goss tells Byrdie. "Their heart and lungs may be ready to fuel a thousand push-ups, but if they haven’t conditioned the muscles in their upper body, they may not have the muscular endurance for even one." The moral of the story? Having both cardio and muscular endurance can make your body stronger all around and help you take on fitness challenges of all stripes.
Physiologically, cardio endurance refers to your body's capacity to use oxygen effectively. Muscle endurance, or your muscles' ability to work hard over a long chunk of time, is a similar concept, says Richey. The higher your endurance, the more reps you can perform, like squats or bicep curls. When you strength-train, your muscles rely on glucose for fuel, he says. But if you have low muscular endurance, your body doesn't deliver oxygen fast enough to convert all the glucose you need to keep pumping iron, and instead, your body produces lactic acid to keep powering through, which can build up and leave you tired and sore afterward, Richey explains. But regular strength training helps your body adapt so that you can slay longer sessions in the weight room.
How Do You Build Endurance?
Endurance is built when you push past your current stopping point and allow your body to adapt to a new one, says Goss, which is why a well-rounded fitness regimen that includes cardio and strength training can help you build and maintain endurance.
If it's cardio endurance that you seek, Richey recommends a straightforward approach. Start by picking a cardio activity of your choice. No worries if running isn't your thing—try cycling, dance, swimming, or another activity. Then increase the duration over time. If you're new to cardio, he suggests exercising with a perceived exertion of 3 or 4 on a scale of 1 to 10 and slowly building up to 30 minutes of continuous activity.
The recipe for muscle endurance is much the same. Goss suggests sticking to a higher-rep, lower-weight regimen—think 12 to 20 reps per exercise with a sustainable weight, as opposed to 5 to 10 reps of all-out effort with a super-heavy dumbbell. The same goes for bodyweight exercises. And if it doesn't feel comfortable to do higher reps of challenging exercises like push-ups, modify them to make those repetitions more accessible. For example, do 15 to 20 push-ups against the wall instead of on the floor, says Goss.
Beyond exercise, eating healthy iron-rich foods and getting quality sleep are two important factors when it comes to building endurance, adds Goss. After all, a well-fueled and well-rested body is better able to tackle training challenges than one that's hungry and tired.
No matter your endurance level, though, listen to your body as you build cardio and muscular strength. If something hurts or doesn't feel right, ease off. "Make sure to respect where you are with fitness and set achievable goals that will challenge you," says Goss.
How to Measure Your Endurance
Endurance is a "use it or lose it" ability, says Goss, so once you build it, you have to work to maintain it. And how you do so depends on your fitness level: If you're new to endurance training, light exercise a few days a week could do the trick, whereas an endurance athlete may require vigorous exercise nearly every day, according to Goss. Check in with a health or fitness professional to help craft a workout plan that suits your experience and goals.
The simplest way to gauge your endurance? Keep a diary. "Write down the date and how long you are able to do an activity, or the highest number of reps you were able to do for a specific exercise in a given amount of time," Goss tells Byrdie. "Check back with your notes after a couple of weeks of training and repeat those exercises. Have you been able to do timed activities for longer periods? Have your reps increased?" Your endurance journal can give you a benchmark for where you started, where you are, and where you're going.
If you'd rather take a deeper dive into your metrics, consider getting a heart rate monitor or fitness tracker to help you monitor and log your endurance during individual workouts and over time. There's plenty of devices to pick from that not only collect your activity data but also track things like sleep quality and stress levels to give you a more holistic perspective on your fitness goals.
And as you embark on your endurance-building journey, whatever that looks like for you, just remember that it doesn't have to be a drag. Richey's tip? "Don’t work so hard that you hate it," he says. "Celebrate and build on your accomplishments."
Hinton PS. Iron and the endurance athlete. Appl Physiol Nutr Metab. 2014;39(9):1012-1018.