How running changes your body

Three women running in park
(Image credit: Getty)

Are you wondering about how running changes your body? The sinewed endurance athletes seen at the Olympics are living proof that regular running can have a significant impact on your body – how running changes your body, however, is a slightly more complicated matter. 

Regardless of whether you get your exercise using one of the best treadmills or you prefer to clock those kilometers in the great outdoors, it’s good to have an understanding of the effects that running can have on your body.

And to help you figure out just that, we spoke to Dr Richard Blagrove, an exercise physiologist at Loughborough University, who talked us through the many positive impacts running can have on your muscles, bones, metabolism, cardiovascular system and mental health. 

So, what are you waiting for? Lace up those running shoes, pump up that music, grab one of the best running watches to help you track your progress and get moving, because plenty of benefits await at the finish line. 

The effect of running on the muscular system

“There are a large number of adaptations at a muscle level following a period of aerobic exercise training, such as running,” Dr Blagrove says.

“These include increases in the size and number of small structures, called ‘mitochondria’, that use oxygen to produce energy, and an increase in the number of small blood vessels that supply muscles with oxygen.”

An increase in the number and size of mitochondria will allow them to produce energy more efficiently, meaning there will be greater quantities readily available to power your working muscles. 

“There is also some evidence that, in older untrained individuals, running can provide noticeable changes in muscle mass, which increases strength,” Blagrove adds. 

The effect of running on bone density

Senior man jogging in park

(Image credit: Getty)

It’s been widely accepted for some time that running can improve bone density. In the late 19th century, German surgeon Julius Wolff created what has now become known as Wolff’s Law – if you’ve been wondering how your workout strengthens your bones, Wolff’s law has the answer. 

Wolff correctly stated that bones will adapt to stresses placed on them, so putting load through your lower body by running will cause the bones in your legs to strengthen over time. 

“Running is an impact activity which means, with each foot contact, the bones in our lower leg in particular are exposed to forces two to three times our body weight,” Dr Blagrove says. “These impact forces are beneficial to our bones and drive changes in bone mineral density, which lowers the risk of developing osteoporosis in later life.”

The effect of running on metabolism

A lot of people ask the question ‘what is metabolism?’ and for good reason, the word metabolism is often heard in health circles, but before we look at its relationship with running, it’s important to understand exactly what it means. 

Metabolism is defined by MedlinePlus as “all the physical and chemical processes in the body that convert or use energy, such as breathing, circulating blood, controlling body temperature, contracting muscles and digesting food and nutrients.”

These processes require energy to complete, which the body draws from calories in the food and drink we consume. The total amount of energy needed by each individual person to function will vary depending on factors such as age, height and weight. It is also affected by an individual’s activity levels.

“When we perform exercise, such as running, our metabolism increases to support the increased energetic demand,” Dr Blagrove says. 

“This helps us burn off calories and (in the) long-term will reduce body fat. When we finish a run, particularly if the run has been at a high-intensity, metabolism will remain elevated for up to 36 hours, meaning we are burning more calories, even while we rest and recover.”

The effect of running on cardiovascular diseases

Is running good for you? When it comes to improving your cardiovascular fitness, you bet it is. The cardiovascular system (also known as the circulatory system) is the network of organs and blood vessels that act as both a delivery and waste removal system, supplying oxygen and nutrients to the body while removing carbon dioxide. 

Cardiovascular diseases are conditions affecting the heart or blood vessels that impair this system, often as a result of fatty deposits building up within the arteries and an increased risk of blood clots. For example, strokes, heart attacks and coronary heart disease.

There is good news for runners and other ardent exercises on this front, as Dr Blagrove explains how staying active can counter these conditions. 

“There is compelling evidence that regularly participating in even a small amount of aerobic exercise several times each week, like running, will reduce our risk of developing cardiovascular disease,” he says.

“Exercise helps to regulate our blood pressure, improves cardiac function, burns excess energy, and improves our insulin sensitivity, which all contribute to a lowered risk of hypertension, type 2 diabetes, and coronary heart disease.”

The effect of running on mental health

Woman running outdoors

(Image credit: Getty)

While we set out to discover the physical adaptations that occur as a result of running, studies show it can also have a positive impact on your mental health. 

One such study published in the International Journal of Environmental Research and Public Health concluded that “running has important positive implications for mental health, particularly depression and anxiety disorders”. However, it admits it is difficult to quantify this impact. 

“There is a large amount of evidence showing that regular running reduces symptoms of anxiety, stress and depression,” Dr Blagrove says. 

“Running is also linked to greater self-esteem and the runners’ high that people often describe after a run can improve mood. Interestingly, regular running has been associated with an improved capacity to learn and reduces cognitive decline in older individuals.”

If you’re new to running as a form of exercise and are keen to reap the mental health benefits it can offer, check out our guide to how to start running, which has lots of tips to help get you off on the right foot. 


  • Seladi-Schulman, J., PhD. (2019, January 28). How Your Workout Strengthens Your Bones. Healthline. Retrieved April 8, 2022, from
  • MedlinePlus. (n.d.). Metabolism. Retrieved April 8, 2022, from
  • Oswald, F., Campbell, J., Williamson, C., Richards, J., & Kelly, P. (2020). A Scoping Review of the Relationship between Running and Mental Health. International Journal of Environmental Research and Public Health, 17(21), 8059.
Harry Bullmore
Fitness writer

Harry Bullmore is a fitness writer covering everything from reviews to features for LiveScience, T3, TechRadar, Fit&Well and more. So, whether you’re looking for a new fitness tracker or wondering how to shave seconds off your 5K PB, chances are he’s written something to help you improve your training. 

When not writing, he’s most likely to be found experimenting with a wide variety of training methods in his home gym or trying to exhaust his ever-energetic puppy. 

Prior to joining Future, Harry wrote health and fitness product reviews for publications including Men’s Health, Women’s Health and Runner’s World. Before this, he spent three years as a news reporter with work in more than 70 national and regional newspapers.