When we talk about exercise, we nearly always refer to physical exercise. Exercise is the physical exertion of the body - making the body do a physical activity which results in a healthy or healthier level of physical fitness and both physical and mental health.
In other words, exercise aims to maintain or enhance our physical fitness and general health. People exercise for many different reasons. Some of them are included below:
- Strengthening muscles
- Optimizing the cardiovascular system
- Practicing specific athletic skills
- Controlling bodyweight
- For fun
- To win
- To socialize
- As a form of escapism.
Contents of this article:
You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.
Fast facts on exercise
Here are some key points about exercise. More detail and supporting information is in the main article.
- Exercise can be broadly categorized as either aerobic, anaerobic or agility training.
- Exercise improves your mood.
- Physical activity after the menopause reduces breast cancer risk.
- Regular exercise improves your sex life.
- Exercise makes you eat less by suppressing appetite hormones.
- Exercise improves your confidence
- Exercise can reduce cigarette cravings for people who are trying to quit smoking.
- Some cancer patients can benefit from exercise; one study explains how exercise can help non-small cell lung cancer patients.
Types of exercise
There are three broad intensities of exercise:
- Light exercise - the exerciser is able to talk while exercising. Going for a walk is an example of light exercise.
- Moderate exercise - the exerciser feels slightly out of breath during the session. Examples could be walking briskly, cycling moderately, or walking up a hill.
- Vigorous exercise - the exerciser is panting during the activity. The exerciser feels his/her body is being pushed much nearer its limit, compared to the other two intensities. This could include running, cycling fast, and heavy weight training.
Scientists from Lawrence Berkeley National Laboratory, Life Science Division in Berkeley, California reported in the journal Arteriosclerosis, Thrombosis and Vascular Biology that brisk walking is as effective as running in reducing a person's risk of hypertension (high blood pressure), high cholesterol and diabetes.
Exercise can also be divided into three broad categories: aerobic, anaerobic, and agility training.
How much exercise do children need?
Children need more exercise than experts think - current recommendations for children in most countries are for them to have an hour of exercise each day. According to scientists from the University of Zaragoza in Spain, however, one hour is not enough for kids.
For children under the age of ten to be protected from heart and blood circulation problems later in life they should have 80 minutes or more of exercise every day, the researchers wrote in the journal BMC Medicine. They added that 20 of those minutes should involve vigorous physical activity.
Recent developments on children's exercise from MNT news
Almost 250,000 children and adolescents in the US were treated in emergency departments for sports-related injuries that included concussion or traumatic brain injury in 2009. Now, the American Academy of Pediatrics have issued new guidelines to improve safety for youths who play one of the most popular sports: football.
Extracurricular sports have long been promoted as a way of keeping children healthy, but new research suggests they could also provide benefits in the classroom, helping children remain engaged and disciplined.
Aerobic exercise has the aim of improving the body's consumption of oxygen. The word aerobic means "with oxygen." Aerobic refers to our body's use of oxygen in its metabolic process (energy-generating process). Most aerobic exercises are done at moderate levels of intensity for longer periods, compared to other categories of exercise.
Jogging for 20 minutes is a form of aerobic exercise that can improve the body's consumption of oxygen.
An aerobic exercise session involves warming up, exercising for at least 20 minutes, and then cooling down. Aerobic exercise involves mainly the large muscle groups.
A physical therapist, Col. Pauline Potts, and an exercise physiologist, Dr. Kenneth Cooper, both in the US Air Force, were the first to use the term aerobic exercise during the 1960s. Dr. Cooper wanted to find out why some very strong people were poor at long-distance running, swimming and cycling. He researched people's performance in terms of their ability to use oxygen with the use of a bicycle ergometer.
In 1968, Dr. Cooper published his book Aerobics. The book included scientific programs using aerobic exercises, such as swimming, running, cycling and walking. The book became a bestseller. All present aerobic programs use Cooper's data as a baseline.
Aerobic exercise is generally performed at a moderate level of intensity over a long period. Running for 20 minutes is an aerobic exercise, while sprinting 200 meters is not. Playing badminton for 30 minutes is an aerobic activity if the movements of the players are fairly continuous. Golf, on the other hand, is not seen as aerobic because the heart rate has not been raised at a sustained level for long enough.
Aerobic exercise is considered to have the following benefits:
- Strengthens the muscles that are involved in respiration - exercises facilitate the flow of air in and out of the lungs
- Strengthens and enlarges the heart muscle - this improves aerobic conditioning - pumping of blood and the heart rate (lowers the pulse of a person when they are resting)
- Tones muscles throughout most of the body
- Reduces blood pressure
- Improves circulation
- Raises the number of red blood cells, in turn facilitating transportation of oxygen
- The sleep quality of insomnia patients can improve with moderate exercise, a study found
- Improves mental health
- A study found that exercise reduces migraine suffering
- Reduces the risk of heart disease and cardiovascular problems
- Helps improve survival rates of patients with cardiovascular diseases significantly, as researchers found
- Stimulates bone growth (high impact aerobic exercise), reduces risk of osteoporosis
- Increases stamina or endurance - aerobic activity increases the body's ability to store energy molecules such as fats and carbohydrates within the muscle
- Increases blood flow through muscles
- Improves muscles' ability to use fats during exercise, thus preserving the intramuscular glycogen.
People who exercise regularly also tend to live longer than those who do not, even if their exercise includes simply brisk walks and they are overweight, researchers from the National Cancer Institute in Bethesda, MD, reported in PLoS Medicine. They added: "This finding may help convince currently inactive persons that a modest physical activity program is ''worth it'' for health benefits, even if it may not result in weight control."
Anaerobic exercise such as weight lifting can improve strength and muscle.
The aim of anaerobic exercise is to build power, strength and muscle. The muscles are exercised at high intensity for short durations. A short duration usually means no more than about two minutes.
Anaerobic means "without air." Anaerobic exercises improve our muscle strength and our ability to move with quick bursts of speed. When thinking of anaerobic exercise, think of short and fast or short and intensive. Anaerobic exercises include:
- Weight lifting
- Intensive and fast skipping (with a rope)
- Interval training
- Any rapid burst of hard exercise.
Oxygen is not used for energy during anaerobic exercise. During this type of exercise a byproduct - lactic acid - is produced. Lactic acid contributes to muscle fatigue and must be used up during recovery before that muscle can be subjected to another anaerobic session.
During the recovery period oxygen is used to give the muscle a "refill" - to replenish the muscle's energy that was used up during the intensive exercise.
Overall, anaerobic exercise uses up fewer calories than aerobic exercise. The cardiovascular benefits of aerobic exercises are greater than the cardiovascular benefits of anaerobic exercises. However, anaerobic exercise is better at building strength and muscle mass, while still benefitting the heart and lungs.
As you build more muscle you will burn more fat, even at rest. Muscles burn more calories per unit volume than any other tissue in the body. A muscly person burns more calories than a non-muscly person, even if while he/she is resting. One study found that resistance training may aid in weight loss.
How does anaerobic exercise work?
When a short, intensive burst of activity occurs, there is a temporary shortage of oxygen being delivered to the working muscles at first. The production of anaerobic energy creates a byproduct - lactic acid. As mentioned above, lactic acid causes muscle fatigue, which is the reason the session cannot last long. However, after regular training the person's body becomes better equipped to handle lactic acid.
After several practice sessions, the body becomes better at getting rid of lactic acid - it also learns how to produce less of it. The body also produces buffers that postpone the onset of fatigue during an anaerobic session.
Anaerobic exercises offer the following benefits:
- The exerciser gets stronger
- The exerciser experiences growth in muscle mass
- Strengthens bones
- Strengthens and protects the joints
- Helps control bodyweight
- The exerciser can withstand a greater buildup of lactic acid and other waste substances, and can eliminate them more rapidly.
On the next page, we look at agility training, yoga and pilates and the potential consequences of a lack of exercise.