What Really Happens to Your Body When You Run Every Day

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You can run every day safely, but even experienced runners benefit from days off to rest and recover.
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There are lots of convincing reasons why people turn to running every day for exercise: You don't need very much equipment, you burn a ton of calories and you reap the positive effects of being in nature (if you run outdoors).

"Running is a full-body metabolic, weight-bearing workout, so the benefits are enormous," Andrew Slane, running coach at Precision Run and Equinox group fitness instructor on Variis, tells LIVESTRONG.com.

"You will see improved cardiovascular and respiratory function, strengthening of all your leg muscles, as well as your core, back and arms, and greater bone density. It is also one of the best calorie-burning cardio workouts you can do."

But can too much of this high-impact sport take a toll on your body? Whether you power up the treadmill or hit the ground running, here's exactly what happens to your body when you go for a run every single day.

Read more from our 'What Really Happens to Your Body When' series.

Your Lower-Body Muscles Grow Stronger

Running every day builds physical fitness and strengthens lower-body muscles. That's because the very act of running fires up these muscles to produce great power mile after mile.

It takes many muscles to make running possible, says Tony Ambler-Wright, a National Academy of Sports Medicine (NASM)-certified personal trainer, master instructor and a certified strength and conditioning specialist (CSCS).

You're already familiar with plenty of them, like the calves, quads and glutes, all of which "ensure the lower extremity and pelvis stay properly aligned," Ambler-Wright says. They help your body "effectively absorb force and store elastic energy, which ultimately translates to greater kinetic energy/force production."

The muscles that make up the calves (the gastrocnemius and soleus) are responsible for lifting the heel and pushing you forward, adds Rachel Tavel, PT, DPT, CSCS, physical therapist at Shift Wellness in New York City.

But other muscles you may not have given much thought to before — like the anterior and posterior tibialis in your lower leg, which help to control and decelerate foot strike — are also challenged and strengthened by a regular running routine.

While running does train your lower-body muscles, improving their overall strength and power is ultimately going to come from strength training. Instead of running every day, consider hitting the weight room on alternate days to prevent muscle imbalances and ensure that each stride is smooth and efficient.

Many running experts recommend running no more than four days a week. More than that, and all the repetitive impact may take a toll on these lower-body muscles.

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Your Core and Back Become More Stable

The muscles of your core also play an important role in running. They not only "transfer force to and from the lower and upper extremities, but they also contribute to pelvic and trunk rotation," Ambler-Wright says. That rotation are necessary for moving from one place to the next effectively and efficiently, he adds.

Your back — your lats more specifically — also work to produce power in your strides. These large, fan-shaped muscles are the only upper-body muscles that attach to both the spine and the pelvis.

"The lat works in concert with the opposite glute to absorb and produce force during the gait cycle," Ambler-Wright says. This tag-teaming movement provides a stabilizing force through the lower back and pelvis.

"This is evidenced by the arms and legs moving in dynamic opposition of each other during running. The faster one runs, the more important this relationship between arm swing and movement becomes," Ambler-Wright says.

To help improve your lat strength, take a break from your daily runs to squeeze in some upper-body workouts. Make sure to also work in some core exercises at the ends of your runs, or tack them onto your lower- and upper-body strength training days.

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Your Breathing Gets More Efficient

Running every day will help you learn how to economize your breath more efficiently over different distances.

That all stems from how you use your diaphragm, the main muscle that controls breathing, which sits between the chest and abs and is a large stabilizer of the core. When you're not breathing efficiently, smaller surrounding muscles are forced to work harder.

"If diaphragmatic breathing is altered or reduced, the secondary respiratory muscles like the scalenes (breathing muscle in the neck), sternocleidomastoid (neck muscle), pec minor (chest muscle), levator scapulae (upper-back muscle) and upper trapezius (upper-back muscle) may be relied on more heavily, leading to shallower, more chest-oriented breathing," Ambler-Wright explains.

"Over time, this may lead to altered rib, shoulder, neck and head alignment, resulting in pain due to overuse of these muscles," he says.

Taking time to do exercises that strengthen the diaphragm and abs can help train these muscles to and in turn increase your oxygen levels while running.

Many running experts recommend running no more than four days a week.

Your Performance Might Plateau

Running does get a little easier the more often you do it, and you'll likely be able to build up in distance by running daily. But just like any type of workout, running the same distance and speed every day can lead to a plateau where you're unable to improve your pace or increase your mileage.

If you're running every day, you're most likely using your slow-twitch muscle fibers and aren't training your fast-twitch muscle fibers enough, which is where power and speed are going to come from. FYI, slow-twitch muscle fibers are responsible for endurance exercise, like running long distances, while fast-twitch muscle fibers are recruited for performing explosive movements, like heavy lifts and sprinting, according to the NASM.

What is ultimately going to make you a stronger and faster runner is adding some strength training into your routine (sensing a theme here yet?). By incorporating some heavy lifts into your training, you'll recruit those fast-twitch muscle fibers, which can help you improve your speed.

Because your quads, hamstrings, glutes, inner- and outer-thigh muscles and core are the primary movers in running, you'll want to focus on strengthening those, says Jonathan Cane, an exercise physiologist, running coach and co-author of Triathlon Anatomy. Do exercises like squats, lunges, deadlifts and glute bridges to help you generate the power to sprint faster and push through steep inclines.

Your Balance May Improve

"Running is a single-leg sport," Tavel says. "You leap and land on one leg at a time," all while maintaining your balance.

Some research shows that running daily can help improve your balance, according to a January 2015 review in the British Journal of Sports Medicine. When you're running, you're actively using your core, back and leg muscles to stabilize. And, as mentioned earlier, your lower-leg muscles are activated to control foot strike, essential for maintaining balance.

But strengthening these areas with resistance training is what's really going to improve your stability and address any muscle imbalances. Are your hips uneven when you run? It could be a sign that one side of your glutes is weaker than the other. Common running form mistakes and muscle imbalances like this can set you up for overuse injuries.

"The glutes are the main muscles connecting the lower extremity to the pelvis, so this connection needs to be strong to help stabilize unilaterally with each stride," Tavel says. "If the glutes are weak, you could be more vulnerable to injury due to instability and poor body mechanics during the gait cycle."

The good news is that unilateral, or one-sided, exercises can help you bolster your balance even further — and make you a more powerful runner. Add unilateral movements such as single-leg deadlifts, split squats and single-leg glute bridges to your routine on your days off from running.

How to Run With Good Form

  1. Run tall. Think of having a helium balloon in the center of the top of your head gently pulling you up.
  2. Relax your shoulders, hands and jaw. Keep your core engaged and firm — not overly tense, but enough to keep you from flailing around.
  3. Don't let your hands cross your midline. Too much twisting of your upper body can cause your feet to cross your midline, which wastes energy and can cause mechanical issues.
  4. Aim for your foot to land gently beneath your center of gravity. Landing too far in front of your center of gravity can lead to both increased risk of injury and decreased speed.

You Could Get Injured

While your muscles and cardiorespiratory system can adapt relatively quickly to a new running routine, it takes much longer for the tendons, ligaments and joint connective tissues to adapt to that stress, Ambler-Wright says. And that means if you increase your mileage every day or don't do a proper warm-up before you run, you could risk injury.

Plus, "if a joint has been previously injured and some degeneration has occurred, running daily could potentially accelerate or exacerbate the condition," he says.

If you run with poor mechanics and/or altered alignment, it may place added stress on the soft tissues and joints in your lower back, pelvis and legs. This can lead to increased wear and tear and possible injury, especially if you run every day.

"By only running, the tissues of the body are stressed in the same way through the same ranges of motion over and over and over," Ambler-Wright says.

Common Injuries From Running Too Often

Some of the most common overuse injuries associated with running, according to the Cleveland Clinic, include:

  • Achilles tendonitis: inflammation of the tendon that connects your calf muscles to your heel bone
  • Plantar fasciitis: irritation of the plantar fascia, the band of connective tissue that connects the heel and forefoot
  • Shin splints: pain or inflammation of the muscles or tendons along the tibia or shin bone
  • Iliotibial band syndrome: tightness and swelling of the iliotibial band, the thick band of tissues that runs on the outside of your thigh, from the hip to the knee
  • Patellofemoral pain syndrome:_ _irritation of cartilage under the kneecap or strain of underlying tendons, also known as runner’s knee

That's why it's important to make sure you take days off from running to prepare so your body can handle the stress of running. Focus on stability and mobility training, as well as recovery strategies, like foam rolling, sleep and nutrition, to help prevent injury, according to the American Council on Exercise (ACE).

Your recovery routine should also include cooling down with stretches after a run, as well as proper refueling. Aim to have a snack with a 3:1 to 4:1 carb-to-protein ratio within 20 minutes of finishing a run to help speed recovery.

"Your body actually needs this time to repair damaged tissue, get stronger and have the energy needed for longer workouts," Cane says. And the faster and more thoroughly you recover, the sooner you can get back to effective running, he says.

Cross training — or incorporating different types of workouts other than running into your routine — can also help prevent injury. Activities such as cycling and swimming work well because they "keep the cardio systems in top shape while doing non-weight bearing aerobic exercise," says Michele Olson, CSCS, a senior clinical professor of sports science at Huntingdon College in Montgomery, Alabama.

You might also want to dabble in some yoga, a great way for runners to both strengthen and stretch.

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Your Heart Will Pump Stronger

People refer to running as cardio for a reason: It improves the strength and efficiency of the cardiovascular system. In fact, a September 2019 randomized controlled trial in the Journal of Sports Science and Medicine shows that running high-intensity intervals can improve maximum oxygen uptake (VO2 max) as much as functional HIIT exercises, such as burpees. The greater your VO2 max, the more oxygen your body can take in and deliver to your muscles.

And while you might think you need to go hard at all times to really reap this reward, it's simply not true. An August 2014 study in the Journal of the American College of Cardiology shows that running just five to 10 minutes a day at slow speeds can reduce the risk of death from all causes and cardiovascular disease.

Yes, intervals make your ticker work harder and can be a greater catalyst for weight loss, but there is something to be said for longer-duration, lower-intensity exercise as well, Ambler-Wright says. Running longer distances allows you to keep the pace easy while going the distance, and experts advise varying the intensity and length of your runs throughout the week.

When you're ready to run longer, experts recommend extending by only 10 percent every other week. So, if you normally run for 30 minutes three days a week, you can extend your run to 33 minutes on one of those days.

Feeling some fatigue from your daily runs? Don't be afraid to take a break and do other forms of cardio, like biking, swimming and dancing. These workouts will help you maintain your fitness while working your muscles and loading your joints in different ways

You Might Lose Weight

Olson doesn't recommend people who are overweight (those with a BMI of 25 to 30) or who have obesity (those with a BMI of 30 or higher) to start running for weight loss because the impact is more pronounced and can cause injuries to the soft tissues in the joints.

But if you've gotten the all-clear from a health care professional to try running for weight loss, expect to burn tons of calories. The number you burn will vary depending on factors like the intensity of your workout and your age and size, but, according to Harvard Health Publishing, a 155-pound person running 12 minutes per mile can burn as many as 298 calories after just 30 minutes.

While you'll need to make adjustments to your diet as well, burning calories with exercise like running — which works multiple muscle groups at once, resulting in that high calorie burn — can certainly help you along a weight-loss journey.

On the other hand, over time, some beginners notice they gain weight from starting a new running routine. This may be due to muscle growth that offsets lost body fat.

Still, because running is so taxing on the muscles and joints, it's best to avoid doing it every day. If you find yourself with a running injury, your weight-loss efforts might be derailed. Instead, add some variety to your routine: Strength training can help you build lean muscle mass and lower overall body fat.

Are you on track to achieve your fitness goals? Download the MyPlate app to keep tabs on the number of calories you burn during your workouts and stay motivated.

The Bottom Line on Running Daily

For most people, running four to five days a week should be the max, allowing you ample time for cross-training, strength training and rest.

Your level of experience should dictate how frequently you decide to run. "With experience, many runners can run five, six or even seven days per week, but early on, I wouldn't recommend more than every other day," Cane says.

"For veteran runners with good mechanics who are relatively injury-free, I have no objection to running every day, though, for most I'd probably prefer to complement their running with some cycling or swimming or other lower-impact cardiovascular activity," he says. Experienced runners have made the necessary muscle adaptations and are better able to handle more volume, whether it's total miles or frequency, he explains.

If you're going to run every day, your training schedule becomes even more important. "It can be safe to run every day, provided that the running program is structured at the appropriate intensities and volume, which has to take into account the individual's training goals and fitness history," Ambler-Wright says.

"You can run most days, but you have to alternate distance and speed," Olson adds. "Some days should be slower, but could be longer runs; some days could be faster but shorter; some days could be on softer terrain, such as grass or bike paths." Switching up the terrain and intensities of your runs can help reduce the repetitive pressure on your joints.

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