Whether you’ve hit a workout plateau or you’re just ready to turn things up a notch, adding more strenuous exercise — also known as high-intensity exercise — to your overall fitness routine is one way to increase your calorie burn, improve your heart health, and boost your metabolism.

However, to do it safely and effectively, there are some guidelines you should follow. Keep reading to learn more about the benefits of vigorous exercise and how to safely dial up the intensity of your workouts.

When it comes to exercise, the intensity of how hard you work out is just as important as the duration of your exercise session. In general, exercise intensity is divided into three categories:

  • low
  • moderate
  • vigorous or strenuous

For an activity to be vigorous, you need to work at 70 to 85 percent of your maximum heart rate, according to the American Heart Association. Examples of vigorous exercise include:

  • running
  • cycling at 10 mph or faster
  • walking briskly uphill with a heavy backpack
  • jumping rope

Low to moderate exercise is easier to sustain for longer periods since you work below 70 percent of your maximum heart rate and, sometimes, well below that level.

To reap health benefits, the Physical Activity Guidelines for Americans recommends that people age 18 and older get one of the following:

  • 150 minutes of moderate-intensity aerobic activity per week
  • 75 minutes of vigorous aerobic activity per week
  • combination of both types of activity spread throughout the week

Increasing your exercise intensity is fairly simple to do. You can still participate in your favorite activities — just at a more vigorous pace.

One of the benefits of more strenuous exercise is that you can reap the same rewards as moderate-intensity exercise but in less time. So, if time is of the essence, doing a more strenuous 20-minute workout can be just as beneficial as doing a slower 40-minute workout session.

Here are some examples of strenuous vs. moderate exercise.

Moderate intensityStrenuous intensity
bicycling at less than 10 mphbicycling at more than 10 mph
walking brisklyrunning, or hiking uphill at a steady pace
jog-walk intervalswater jogging/running
shooting baskets in basketballplaying a basketball game
playing doubles tennisplaying singles tennis
raking leaves or mowing the lawnshoveling more than 10 lbs. per minute, digging ditches
walking stairsrunning stairs

Besides being more efficient, turning up the heat on your fitness sessions can benefit your health in a variety of ways. Let’s take a closer look at some of the evidence-based benefits of a higher intensity workout.

  • Higher calorie burn. According to the American Council on Exercise, working out at a higher intensity requires more oxygen, which burns more calories. It also contributes to excess post-exercise oxygen consumption (EPOC) or the “afterburn effect” that allows you to continue burning calories even after you finish working out. This means your metabolism will stay elevated for longer after a vigorous exercise session.
  • More weight loss. A higher calorie burn and an elevated metabolism will help you lose weight more quickly than doing low- or moderate-intensity exercise.
  • Improved heart health. According to a 2012 study, high- and moderate-intensity exercise appears to offer low chance of cardiovascular events, even in those with heart disease. Cardiovascular benefits may include improvements in:
  • Improved mood. High-intensity exercise may also boost your mood. According to a large 2015 study that analyzed the data of more than 12,000 participants, researchers found a significant link between strenuous exercise and fewer depressive symptoms.
  • Lower risk of mortality. According to a 2015 study, researchers found that vigorous activity may be key to avoiding an early death. The study, which followed 204,542 people for more than 6 years, reported a 9 to 13 percent decrease in mortality for those who increased the intensity of their exercise sessions.

So, how do you know for sure that you’re exercising at a strenuous level? Let’s look at three ways to measure the intensity of your physical activity.

1. Your heart rate

Monitoring your heart rate is one of the most reliable methods for measuring exercise intensity. Exercising at 70 to 85 percent of your maximum heart rate qualifies as vigorous exercise intensity.

What is your maximum heart rate?

Your maximum heart rate is the fastest your heart can safely beat. To find out what your maximum heart rate is you need to subtract your age from 220. For example, for a 40-year-old person:

  • 220 bpm (beats per minute) minus age
  • 220 – 40 = 180 bpm

To work out at a vigorous pace, you’ll want to exercise within 70 to 85 percent of your maximum heart rate. For example:

  • 180 x 0.70 (70 percent) = 126
  • 180 x 0.85 (85 percent) = 153

For a 40-year-old person, a vigorous training range is 126 to 153 bpm.

You can check your heart rate while you’re working out by wearing a heart rate monitor or taking your pulse.

2. The talk test

The talk test is one of the easiest ways to measure exercise intensity.

  • If you find it difficult to carry on a conversation, you’re probably working out at a vigorous or strenuous pace.
  • If you can talk fairly easily with some breathlessness, you’re likely exercising at a moderate pace.
  • If you find it easy to sing out loud, your pace may be too slow. To get more benefits from your workout, you may want to consider picking up the pace.

3. Rate of perceived exertion (RPE)

The rate of perceived exertion (RPE) scale is a subjective measure of exercise intensity.

When using RPE, you’ll pay attention to your heart rate, breathing, and muscle fatigue, and rate your exertion level based on a scale that ranges from 1 to 10. No exertion is rated as a 1 and maximum effort is rated as 10.

To be considered vigorous, an activity should meet or exceed a level of 6 to 7, which is considered hard on the RPE scale. This includes jogging, biking, or swimming. Running without stopping is ranked as 8 to 9 on the RPE scale.

Adding strenuous activity to your weekly workout routine requires some careful planning. Fortunately, many of the activities that you do at a moderate level can easily be performed at a higher intensity.

One way of incorporating vigorous aerobic activity into your routine is to do a high-intensity interval training (HIIT) workout. This type of workout combines short bursts of intense activity — typically performed at 80 to 95 percent of your maximum heart rate — with recovery periods at 40 to 50 percent maximum heart rate.

To sustain this level of training, consider following a 2:1 work to rest ratio. For example, a treadmill workout or outdoor running session could include:

  • running at 9 to 10 mph for 30 seconds
  • followed by walking at 3 to 4 mph for 60 seconds
  • alternating this work-to-rest ratio for 20 to 30 minutes

Playing a fast-paced sport like soccer, basketball, or racquetball is another effective way to add strenuous activity to your fitness routine. Participating in cycling classes or swimming laps are other ways to build more strenuous exercise into your workouts.

Before you turn up the intensity on your workouts, it’s important to keep the following safety tips in mind.

Check with your doctor

If you have a health condition or you haven’t been active in a while, make sure you talk to your doctor before you start a high-intensity exercise routine. Your doctor can advise you on a safe level of exercise or how to become more active in the safest way possible.

Build up the intensity slowly

Going from low- or moderate-intensity workouts to vigorous exercise requires time and patience. While you may be ready to jump in with both feet, the safest way to add more vigorous exercise is to do it in bite-size increments. Pushing yourself too quickly can result in injuries and burnout.

For example:

  • Week 1: Swap out one moderate-paced cardio session for a HIIT workout.
  • Week 2: Swap one moderate-paced session with a HIIT workout, and also add a circuit strength training session to your weekly routine.
  • Week 3 and 4: Repeat weeks 1 and 2 before you start adding more high-intensity exercise to your weekly routine.

It’s also a good idea to space out your vigorous workouts throughout the week. Try not to do two strenuous sessions back-to-back.

Don’t forget the recovery time

Your body requires more time to recover from a vigorous workout compared to a low- or moderate-intensity session.

To help your body recover, make sure to always include a cooldown and stretch routine after strenuous physical activity.

Stay hydrated

Staying hydrated is especially important when you’re exercising hard. Not drinking enough fluids can affect the quality of your workout and make you feel tired, lethargic, or dizzy. It may even lead to headaches and cramps.

Turning up the intensity of your workout sessions can be an effective way of boosting your overall health and fitness. It’s also an easy way to save time when trying to fit a workout into your day.

To play it safe, always start slow and pay attention to how your body feels.

While vigorous exercise offers many health benefits, it’s not appropriate for everyone. If you have a health condition or you haven’t been active in a while, make sure to talk with your doctor before working out at a more strenuous level.