With the battle for revved up metabolism, improved cardiovascular fitness, and increased fat-burn, interval training reigns supreme in Fitness Stadium  . But when it comes to getting the maximum benefits from interval training, factors like fitness level and goals play a role in determining how often to perform these often-intense regimes.
Research suggests there is little difference between the amount of strength gained for men and women when training under the same program, allowing them to train at comparable frequencies for similar results . But it turns out women might find intense workouts, like interval training, slightly easier (sorry, boys!). Research suggests women tend to have a slower rate of fatigue and faster recovery from intense exercise as compared to men . Talk about girl power! Regardless of gender, interval training programs should be incorporated gradually into a fitness routine.
To avoid injury and maximize workout efficiency, interval training should be done at different frequencies and intensities depending on fitness level.
- Workout Newbie: Incorporate interval training slowly. Sedentary people (who exercise less than twice a week) tend to experience greater muscle shrinkage, a higher risk for heart and metabolic diseases, and increased weight gain compared to those who are more frequently active  . But because of its intensity, interval training can also put a great deal of strain on the heart and should be introduced into an exercise routine slowly and carefully. A small percentage of people are at risk for injury and health complications when starting intense workout regimes.
According to Greatist Expert Jen Cassetty, people have to be conditioned for physical stress during a workout. Individuals who don’t work out often have to get their hearts and muscles warmed up before undergoing bursts of intense cardio, so consider doing lower intensity cardio (treadmill, elliptical, bike) the day before starting interval training. Greatist Expert Matt Delaney advises people who are very overweight or have a history of heart problems to avoid interval training while starting a fitness program. People over 40 should also complete a physical examination before undergoing an intense exercise program like interval training.
- Workout Regular: For those who lead moderately active lives (exercise 2-4 times a week), try interval training 1 to 2 days per week, along with lower intensity cardio (i.e. treadmill, elliptical, bikes) on alternating days.
- Workout Guru: For an added challenge, those at more advanced fitness levels living very active lives (who exercise more than 4 times a week) can increase the frequency and intensity of the “bursts” during interval training. Delaney advises varying the work (bursts) to rest (less intense cardio) ratio when performing interval training. To make an interval training session more difficult, simply increase the work to rest ratio (hint: less rest)!
For those looking to:
- Improve Cardiovascular Health: Interval training can help strengthen the heart to increase circulation, decrease cholesterol and fat levels, and lower the risk of heart disease. Cassetty advises that although cardio is good for the heart, interval training should not be performed often if improving cardiac health is the main goal. Interval training isn’t ideal for daily workout routines and puts strain on the cardio-respiratory system, so try opting for more traditional cardio sessions.
- Lose Weight/Tone Up: Studies suggest interval training not only revs up the metabolism, but it is also very effective in reducing body fat, especially around the abdomen  . However, don’t assume steady state aerobic exercise is entirely ineffective. Delaney believes that lower intensity (“steady state”) cardio is also effective at fat loss and can be performed in conjunction with interval training on alternating days to allow for proper muscle recovery.
- Maintain Muscle Mass: Want the burn without losing muscle? Proceed with caution. Performing too much cardio can potentially cancel out muscle gains by leaving the body without enough calories to grow and sustain muscles. Greatist Expert Noam Tamir and Cassetty recommend not doing interval training very often to avoid overtraining muscles or losing existing muscle mass. But incorporating interval training and additional strength training into an exercise routine can help build leaner, more defined muscles.
Customized For You — The Interval Training Game Plan
How often should one do interval training? Follow this custom flowchart for a personalized interval training plan! These recommendations are based on research and opinions from our Greatist Experts, but some people may prefer incorporating more or less interval training into their weekly workout routine.
Illustration by John Block
Tamir emphasizes the importance of quality over quantity, avoiding high-intensity, back-to-back days of interval training to prevent overtraining muscles and decreased energy. For those looking for more of these short and powerful workouts, he advises performing interval training 2 to 3 times a week for all fitness levels and 3 to 4 times for those looking to increase oxygen uptake (VO2 max). Delaney believes in a solid 1:1 interval training to cardio ratio where one day of interval training is followed by a day of steady state, lower intensity cardio.
Be aware of personal comfort levels, and increase the frequency and intensity of interval training sessions gradually as the body adapts. Because the rules of “how often” interval training should be done are dependent on individual starting points and goals, Cassetty recommends that the Frequency, Intensity, or Time (FIT) of each interval training session be increased by 10% after each week until the goal is reached.
Ready to get started? Check out our Interval Training for Newbies for more specific interval training routines for people of all fitness levels!
Special thanks to Greatist Experts Jen Cassetty, Matt Delaney, and Noam Tamir for their contributions to this article.