Home › Blog › High-Intensity Interval Exercise vs. Endurance Exercise for Cell Health

There’s been a battle brewing in exercise circles ever since CrossFit was introduced. Should you focus on shorter bursts of high-intensity exercise, or should you spend more time on endurance activities? Now a new study weighs in on this debate while focusing on cell health.

Understanding Cell Anatomy and the Mitochondria

Humans are made up of many types of cells, and different cell types serve different areas of the body. A leukocyte, for example, is a white blood cell produced by the bone marrow that functions as part of the immune system, defending the body from foreign invaders and infection, while a chondrocyte is a cartilage cell that makes up and maintains the protective cartilage tissue between the joints. A cell consists of many structures called organelles, including the nucleus, cytoplasm, mitochondria, and much more. Our DNA, which houses our individual and unique genetic makeup, also lives in our cells. Our feature study today focuses on exercise and its effect on the mitochondria of the cell, so let’s examine the mitochondria.

Mitochondria are the cellular powerhouses or the batteries that drive the cell. They do this by converting the nutrients that we consume in our food into a chemical energy that powers the cellular machinery. Like any battery, our mitochondria can become sluggish and even lose power altogether. This is why it’s important to support our cell function by keeping our mitochondria at full charge. One way to do this is exercise, but how much and what types of exercise do we need to keep our mitochondria fuel gauge on full? Let’s take a look.

Bursts of Intense Exercise vs. Continuous Moderate Exercise

Our idea of “cardio” through the ’90s and early 2000s focused on the idea that endurance work was great for our heart. However, this past decade a new idea has emerged. Maybe going bigger for less time is better?

The new study set out to dig deeper and determine how the mitochondria in the cells respond to different levels of exercise. Researchers compared three different intensity levels of exercise to determine the effects on mitochondrial function:

1. Continuous cycling for 30 minutes (moderate intensity, 50% effort)
2. Five interval cycling sessions consisting of 4 minutes of cycling and 1 minute of rest (high intensity, 75% effort)
3. Four sprint cycling sessions consisting of 30 seconds of cycling and 4.5 minutes of rest (maximum intensity, 100% effort).

The results? Similar improvements in mitochondria function were found in all three levels of exercise. For example, mitochondria response after just two minutes of the 30-second bursts of sprint cycling (maximum intensity, 100% effort) was comparable to a full 30 minutes of continuous cycling (moderate intensity, 50% effort).

What do these findings mean exactly? Healthier mitochondria mean healthier cells and tissues and a lower risk of certain diseases. This study shows that whether you like to work out at a moderate pace for 30 minutes or you prefer those short, intense intervals of exercise, the benefits to your cells are the same. The key is to just find what works for you and exercise!

The Reasons to Exercise Are Endless

Mitochondria support isn’t the only reason to exercise. The benefits of exercise are endless, but let’s review a few. While studies seem to vary drastically on the effects of exercise on dementia, with some showing improvements in cognitive decline and some showing no improvements, they do at least seem to agree that fitness levels are improved in this population with exercise. For those genetically prone to obesity, exercise has been shown to lower that genetic risk, especially in older (age 70+) people. The links between exercise and heart health are very well known, but one study found that even those starting an exercise regimen in middle age can reap those heart-health rewards. Another big benefit of exercise is a healthy immune system, especially as we age.

The upshot? For me, this study validates the idea that on days where you don’t have the time and your body is up for it, just hitting it really hard for a short time can count as getting a workout in that may help modify or keep your health. The downside of CrossFit as we see in the clinic is the injury rate, which seems much higher. Hence, like everything, it’s all about balance!

Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile