When you think of a runner’s body, you probably think of a certain body type: long, lean, and leggy. However, runners come in as many sizes and shapes as everyone else, and each body will respond in its own way to training.

Even at the elite level, a sprinter’s body is going to look different from a marathoner’s body, and a sprinter’s training will look very different from that of a distance runner.

Add the myriad fitness runners, bucket list marathoners, and people just trying to increase their endurance or burn a few calories, and you’ve got a wide range of silhouettes — all of which should be considered “runners’ bodies.”

That said, building a running habit will make an impact on your body, often in unexpected ways. Below, we’ll look at the ways running can change your body — inside and out — when you begin to take it seriously.

Here are 9 things running does for (and to) your body:

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Running is the OG of cardio — even athletes in other sports use it to help increase endurance.

Whether you run long and slow for staying power or practice sprints to increase your explosive power, running stresses your heart, lungs, and vascular system to increase your cardiorespiratory strength and endurance (1).

Running positively influences your blood pressure and circulation and significantly reduces your risk of dying from cardiovascular disease. But it also decreases your risk of death from any cause by about 27% (2).

Running is a high impact, weight-bearing activity, which means that the rhythmic pounding of the pavement stresses your bones in a way that can be very healthy. Your bones respond to the stress by getting stronger in order to handle the recurring impact.

This is a profound benefit for your lower body, but if running is the only exercise you do, you may want to add some weightlifting for your upper body for overall balance. Still, running can help improve bone density, which is of great benefit as we age (3).

The repeated stress on your body has its upside, but there is also a downside.

In a 2018 study, injury incidence among runners was 62.4%, while in a 2020 study it was closer to 30% (4, 5).

But either way, running can take its toll. An injury may be something acute, such as a rolled ankle, or it may be a chronic injury, such as a stress fracture or shin splints.

Unfortunately, novice runners are injured more often than experienced recreational runners (6).

Knowing how to avoid overdoing it and listen to your body when it needs a break can help reduce the risk of injury, as can stretching and recovering properly between workouts.

Running is a high intensity workout and burns a lot of calories, which is great news for anyone trying to lose weight (7).

Your body burns calories at a higher rate for a period of time after your workout is done — especially after a higher-intensity workout.

When your body is depleted, however, it can be easy to overeat. Taking in a small snack high in protein and whole carbohydrates immediately after your run can help stave off excessive “runner hunger.”

Running works your legs — quads, hamstrings, and calves — plus your hips and glutes. Your inner thighs, abs, and shoulders help, but the large muscles of your hips and legs do most of the work.

Try to run on a variety of surfaces (track, trail, and asphalt) to get variety in the stress on these muscles, which can help you not only avoid injury but also build up more balanced strength. Include occasional hills to get even stronger.

Running is one of the most beneficial forms of exercise, but if you’re not doing other activities too, you’ll risk muscle imbalance and potential injury (8).

Lifting weights is one of the best options because it can strengthen the bones of your upper body and improve your overall posture, balance, and physique.

Strengthening your legs with unstable or single-leg exercises such as lunges or one-legged squats can also help strengthen the stabilizing muscles of your hips and even out any muscle imbalances.

Participating in a low- or no-impact activity such as yoga, indoor cycling, or swimming can help you keep your fitness level high while giving your bones and joints a break from the impact of running.

Studies suggest that runners experience fewer sleep disturbances and less daytime sleepiness than nonrunners. However, running at a moderate intensity may be better for improving sleep quality than running vigorously (9, 10).

Studies have shown numerous connections between running and improved mental health and mood (11, 12).

And while any running will confer these benefits, running outside might offer even more (13).

Running outside is a great excuse to get away from your desk or your never-ending to-do list. Fresh air is good for your lungs, your brain, and your emotional state. Navigating your route stimulates your mind-body connection and adds an element of play.

Plus, the vitamin D boost from the sun can benefit your immune system, eye health, and bone health (14).

No one form of exercise is the only one you’ll ever need, but if you’re looking for a strong body and an endorphin boost, running is close to perfect.

If you’re new to running, start small, progress thoughtfully, and listen to your body. Cross-train a bit for balance, and eat an overall nutritious diet. Your very best runner’s body is possible.