What happens to your lungs and heart when you exercise?

Exercise has many positive effects on heart health. A regular exercise routine can help:

  • Lower blood pressure
  • Lessen risk of developing diabetes
  • Maintain healthy body weight
  • Reduce inflammation throughout the body

“One of the key benefits of exercise is that it helps to control or modify many of the risk factors for heart disease,” says Dr. Kerry Stewart, director of Clinical and Research Exercise Physiology at Johns Hopkins Bayview. “Smoking is another big factor for heart disease, and if you exercise regularly you’re unlikely to take on a bad habit like smoking, or quit if you already are a smoker.”

Additional benefits of exercise:

  • Improves the muscles’ ability to pull oxygen out of the blood, reducing the need for the heart to pump more blood to the muscles
  • Reduces stress hormones that can put an extra burden on the heart
  • Works like a beta blocker to slow the heart rate and lower blood pressure
  • Increases high-density lipoprotein (HDL) or “good” cholesterol and helps control triglycerides

A number of studies have also shown that people who exercise regularly are less likely to suffer a sudden heart attack or other life-threatening cardiac event.

While exercise has benefits in and of itself, the best way to prevent heart disease is to combine exercise with a healthy diet. Exercise alone can help with weight loss over a long period of time. But a short-term approach is to reduce the number of calories you take in through diet, while increasing the calories you use through exercise.

Ideal exercise for the heart

The best exercise has a positive effect on the heart and improves the skeletmuscular system.

The American Heart Association and the American College of Sports Medicine both recommend combining aerobic exercise (jogging, swimming, biking) with resistance training (moderate weightlifting). Together, these two categories of exercise produce the greatest benefit for preventing and managing heart disease.

Exercise and pregnancy

If you’re having a healthy pregnancy, and you exercised regularly before you were pregnant, it’s beneficial to keep up a moderate routine. This regimen can include walking, swimming or bike riding. You’ll continue to receive the same cardiovascular benefits.

If you’re pregnant and everyday exercise has not been part of your life, you should probably stick with a milder exercise. In both instances, it makes sense to seek advice from your physician.

Sources for exercise intelligence

The National Institute of Health, the American Heart Association, and the American College of Sports Medicine are all good sources for assistance in choosing the right exercise routine.

Johns Hopkins has a clinical exercise center which offers medically supervised programs and exercise guidelines based on scientific evidence. We evaluate fitness levels and consider medical history before starting people on exercise regimens. There are similar medical fitness centers throughout the country.

How much exercise and how often?

General guidelines call for a combination of aerobic exercise and resistance training. Try to get in a minimum of 30 minutes of aerobic exercise such as walking, cycling or swimming at least five days a week. Do moderate weightlifting to tone muscles and build muscle endurance twice a week, or frequently enough to cover the major muscle groups.

How do you know when you’re making progress?

There are many ways to chart your exercise progress. Three of the most common are target heart rate for aerobic exercise, number of repetitions for weight training, and fat vs. muscle body composition.

  • Target heart rate – The more fit you are, the harder you’ll need to work to reach your target heart rate. For example, in the first month you may need to walk 3 mph to reach a heart rate of 120, while in the second month in order to reach the same heart rate, you need to walk 4 mph or find a steeper hill. Your fitness is improved and your heart is working more efficiently.
  • Reps – The more weight you can lift 12-15 times without straining, the stronger and more durable your muscles are. For example, you start out struggling to curl a 15-lb. dumbbell 15 times, and then add three to five pounds when it becomes easy.
  • Body composition – Exercise more and your body will change shape: you’ll lose fat, specifically around the waist, and gain muscle. A looser pair of pants or skirt is a distinct sign of progress.

Knowing when you’re overdoing it.

Setting a target heart rate with a qualified trainer or health professional is the simplest way to keep your workout within a healthy range.

  • Stay within your target heart rate, and you’re working out at the right level.
  • Go above your target heart rate, and you’re probably working too hard.
  • Stay below your target, and you’re not working hard enough to gain the most cardiovascular benefit.

An important sign of overwork is fatigue and soreness that stays with you longer than a day or two after you exercise. Any persistent pain could mean you’ve overused or have injured a muscle.

How to stick with an exercise routine

The key to a successful exercise routine is staying interested and motivated. Here are a few ways to keep exercise a lifelong habit:

    Set aside a specific amount of time each day for exercise and work it into your schedule. Work out with a friend. Or join a gym and work out in a group. Either scenario creates mutual support and healthy competition to keep things interesting. Keep a simple log to chart your progress. Create your own record or graph on a spreadsheet, or use one of the many programs available on the Internet. If you jog or cycle, use a heart rate meter or speedometer to help you set and reach goals.

Using exercise to tune up your cardiovascular health

“If we compare a person’s initial fitness response to testing, to responses three to six months later, we see progress,” says Dr. Stewart. “The oxygen consumption will be higher. The time on the treadmill will be longer. The heart rate and blood pressure will be lower. It’s like tuning up your engine. Only the engine is your heart and the body’s circulatory system for distributing blood, and it’s working more efficiently.”

What happens to your lungs and heart when you exercise?
Bring Science Home

Bring Science Home: Activity 17

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Key concepts

Cardiovascular system Exercise

Energy and metabolism

From National Science Education Standards: Personal health

Introduction
When you exercise, do you notice that you get out of breath? What about feeling your heart rate—your pulse—increasing? These two changes are not coincidental—they are both important, and natural, reactions of your cardiovascular system to exercise.

From your brain down to your fingers and toes, your body needs plenty of oxygen to keep going. That oxygen is carried through your body in the bloodstream. Blood is pumped through the heart and picks up oxygen as it passes by the lungs. 

Let's track your heart kicking it into high gear during exercise. But don't get moving just yet; first we need to count your resting heart rate.

Background
When you are exercising, your muscles need extra oxygen—some three times as much as resting muscles. This need means that your heart starts pumping faster, which makes for a quicker pulse. Meanwhile, your lungs are also taking in more air, hence the harder breathing.

So, getting out of breath while exercising is just a sign that your muscles are working. The more you exercise, the more efficient your body will be at getting oxygen to your muscles, so you can exercise more without getting out of breath. Of course, pushing exercise too hard can be dangerous and, if you feel faint, you should stop the activity.

Materials •    Stopwatch or timer with a second hand •    A person who has been relaxing for at least 15 minutes •    Room to do jumping jacks

•    Pencil and paper

Preparation •    Start this activity well rested (sitting down to read for 15 minutes or so should do the trick). •    Have a stopwatch handy.

•    Note: Be sure to drink plenty of water when you exercise. All of that work makes your body lose water through sweat—as well as moisture that is exhaled when you're breathing quickly.

Procedure
•    While you are still sitting, put two fingers (not your thumb, which has its own strong pulse) on the underside of your wrist. Can you find your pulse? •    Count the number of heartbeats you feel for 30 seconds. Write that number down and multiply it by two. That's your resting heart rate: the number of times your heart beats every minute when you are not moving much.

•    Notice your breathing. How many breaths are you taking every minute?

•    Now, get ready to get moving! Make sure you have room enough for jumping jacks, and keep that stopwatch handy. •    Do 20 jumping jacks (or as many as it takes to get out of breath). •    Without resting, count the number of heartbeats you feel in 30 seconds. Write that number down and multiply it by two.

•    How much did your heart rate increase after the jumping jacks?


•    How many breaths did you take in a minute after the jumping jacks?
•    How did your breathing change?
•    Try other activities and see how they affect your heart rate and breathing. What does that mean about how much oxygen each one requires—and how much your muscles are moving?
•    After you exercise, try seeing how long it takes for your heart rate to return to its resting rate.

Read on for observations, results and more resources.

Observations and results
What were your resting and exercising heart rates? How long did it take your heart rate to go back down to normal? Was it before or after you had caught your breath?

As you exercise more, your body gets more efficient and does not require as much heavy breathing or quick heart pumping. People who exercise regularly can do so longer without getting out of breath as quickly. They also tend to have heart rates that return to their resting levels more quickly after physical activity.

But of course, oxygen is not the only substance the body needs. We also need food for fuel. When we eat food, some of it is broken down by the body and transformed into the energy that gets us moving (these energy units are known as "calories"). More food does not always mean more energy. It depends on the type of food you are eating and how your body breaks the food down. For instance, the body can break down sugar and other processed carbohydrates, such as white bread, quickly. But sustained energy is better gained from foods that are harder to break down, such as lean protein and whole grains.

While breathing at different rates helps control the amount of air the body uses, the amount of energy from food the body uses is controlled much differently. If the body gets way more energy (or calories) than it can burn off, it will often store it away as fat.

What are some ways you and your friends and family can get more physical activity every day?

Share your jumping heart rate observations and results! Leave a comment below or share your photos and feedback on Scientific American's Facebook page.

More to explore
"If a Person's Lung Size Cannot Increase, How Does Exercise Serve to Improve Lung Function?" from Scientific American
"Does Exercise Really Make You Healthier?" from Scientific American
"Your Heart & Circulatory System" overview from KidsHealth
"Target Heart Rate for Children" table from Horizon and Blue Cross Blue Shield
Wallie Exercises by Steve Ettinger, ages 4–8
The Amazing Circulatory System: How Does My Heart Work? by John Burstein, ages 9–12

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What happens to your lungs and heart when you exercise?
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What happens to your lungs and heart when you exercise?