Should You Be Doing Cardio on Rest Days?

As tempting as the couch might be on your rest days, research shows you’re likely to reap more benefits from staying active.

Exercise experts agree that light to moderate cardio on rest days—between high-intensity workouts—offers more benefits than staying stationary. A walk, light hike, or swim helps the body integrate intense workouts by promoting circulation, sending extra nutrients to the muscles, clearing workout byproducts, and alleviating residual soreness.

Like most questions in the world of health and wellness, whether or not you need active rest days depends on the type of exercise you do, as well as other individualized factors like overall stress.

WHY ARE REST DAYS IMPORTANT?

When you engage in high-intensity exercise, you’re actually causing damage to the muscles themselves. These microtears signal the body to send its natural repairmen to the scene to assess the trauma and start rebuilding. For example, within five hours of intense weight-lifting, the nuclei of the muscle cells migrate close to each microtear and signal proteins to start sealing the wounds while mitochondria address excess calcium seeping in through the muscle tear.^[1]

This complex process of cellular reconstruction is usually complete about 24 hours post-workout, meaning you should be ready to get back in the gym the following day. As scary as “microtears” can sound, this is a completely natural and beneficial process, as the repair process in the tissue leads to the larger muscles many athletes and gym-goers are seeking.

Muscle soreness, which was previously attributed to a build-up of lactic acid metabolic byproducts, usually peaks a day or two after exercise in response to the cascade of repairs. This is now more aptly named “delayed onset muscle soreness,” and is no cause for concern. It usually diminishes as the muscles become accustomed to a particular exercise or movement over time.  

While exercising is a positive move toward health and wellness, intense or extreme workouts stress the body in physiological terms. Exercise strains the sympathetic nervous system, causing a cascade of responses as the body attempts to maintain homeostasis in its respiratory, cardiovascular, and metabolic functions. More nutrients are utilized quickly, more carbon dioxide must be offloaded, and hormones are produced and excreted differently.

Enter the concept of “rest days.” While regular exercise is a key component of a healthy lifestyle, offering both physical benefits and mental-emotional benefits, rest is also a necessary part of this process. The body needs time to consolidate this hard work, replenish energy and nutrient stores, and seal those muscle fiber micro-tears with cumulative scar tissue.

When Do You Need Rest Days?

Rest days give your body a well needed and well deserved break from the rigors of an intense workout routine. While research points to the need for a rest day at least once every 7-10 consecutive days, it’s also important to listen to your body and respect its unique and ever-changing needs.

If you’re busy fighting off a virus, recovering from an injury, not getting adequate sleep, or are embroiled in a stressful work season, you will likely need to take rest days 2-3 times per week. Pushing yourself past the point of exhaustion on a regular basis and ignoring the signals to rest is associated with more injuries in the long run.

Ask yourself the following three questions for signs that you might be overdoing it at the gym:

1. Are you feeling fatigued most days?
2. Are you having trouble sleeping through the night?
3. Do you hear negative self-talk when you consider cutting back on the workouts?

While moderate exercise helps with these concerns, intense exercise with no rest days can exacerbate them.

If you find it difficult to allow yourself a rest day or are concerned you might be exercising compulsively, talk with your functional doctor about healthy lifestyle habits. They can help you navigate the intense world of fitness and develop the right routine for your needs, integrating targeted dietary supplements for recovery and balancing body and mind.

It’s crucial to pencil in days for relaxation and recovery as part of a healthy fitness routine. The more rigorous your workout, such as HIIT (high-intensity interval training) or heavy resistance training, the more important it is to schedule rest days. If your regular workout routine consists of light to moderate exercise, walking, stretching, and tai chi, you might not need any rest days at all.

RELATED CONTENT: DOES SLEEP IMPACT WEIGHT LOSS?

Is it Important to Do Cardio on Rest Days?

As long as you’re not fatigued or recovering from an injury, it’s generally beneficial to engage in some cardio on rest days. Sometimes called “active recovery days,” these rest days are a change in your regular routine, rather than a total absence of exercise.

Light to moderate cardio, like walking, hiking, swimming, and gentle yoga classes help you keep moving, which in turn supports healthy blood and nutrient circulation to the muscles, alleviating residual soreness. As the body integrates your high-intensity work by repairing microtears in the muscles, it also cleans up the chemical byproducts of exercise, such as lactic acid and hydrogen ions.

Research suggests that for the professional or the average gym-goer, exercise is most beneficial when you vary the intensity.^[2] Athletes are familiar with the concept of periodization, where physical training and targeted exercises are rotated and staggered throughout the season to allow specific muscle groups to better integrate workouts and fully recover. Light to moderate cardio on your rest days is the perfect juxtaposition to the high-intensity training of your regular workout routine.

Bottom Line: Just Keep Moving

While spending the day laid out on the couch binge-watching your favorite show sounds like the ideal rest day after a hard workout, research indicates it’s not the best idea for reaching your overall fitness goals.

Listen to your body. The more intense your workouts are, or the newer you are to the workout world, the more rest days you’ll likely need. Any positive progress is beneficial toward reaching your fitness goals, so don’t get overwhelmed trying to do everything perfectly every day.

Experts agree that physical movement on most days is beneficial, so just keep moving. Push through your high-intensity workouts and support recovery by engaging in activities you enjoy, like yoga or swimming, on your rest days.

[2] Issurin V. Block periodization versus traditional training theory: a review. J Sports Med Phys Fitness. 2008 Mar;48(1):65-75. PMID: 18212712.