Exercise intensity
Encyclopedia
Exercise intensity refers to how much work is being done when exercising. The intensity has an effect on what fuel
the body uses and what kind of adaptations the body makes after exercise (i.e., the training effect). Intensity is the amount of physical power, expressed as a percentage of maximum, the body uses in performing an activity. For example, it defines how hard the body has to work to walk a mile in 20 minutes.
or fat
) depending on the intensity and heart rate. The Heart Rate column below is an estimate for a 20 year old with a Max Heart Rate
(MHR) of 200.
. This efficiency is accomplished by increasing the number of capillaries in the muscle.
.
is a muscle and can be trained to become stronger and more efficient. This intensity of exercise places a load on the heart causing it to become stronger so it can pump more blood in one contraction
.
- causing a quick build up of lactate (lactic acid
). This kind of training, despite being very painful, improves the body's anaerobic capacity - the production, removal, and tolerance to lactic acid.
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
the body uses and what kind of adaptations the body makes after exercise (i.e., the training effect). Intensity is the amount of physical power, expressed as a percentage of maximum, the body uses in performing an activity. For example, it defines how hard the body has to work to walk a mile in 20 minutes.
Fuel used
The body uses different amounts of fuels (carbohydrateCarbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
or fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
) depending on the intensity and heart rate. The Heart Rate column below is an estimate for a 20 year old with a Max Heart Rate
Heart rate
Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....
(MHR) of 200.
| Intensity (%MHR) | Heart Rate (bpm) | % Carbohydrate | % Fat |
|---|---|---|---|
| 65-70 | 130-140 | 40 | 60 |
| 70-75 | 140-150 | 50 | 50 |
| 75-80 | 150-160 | 65 | 35 |
| 80-85 | 160-170 | 80 | 20 |
| 85-90 | 170-180 | 90 | 10 |
| 90-95 | 180-190 | 95 | 5 |
| 100 | 190-200 | 100 | - |
Training Effect
The effect achieved by exercise is affected by the intensity. The intensity and amount of activity needed to achieve many health-related and fitness benefits are less than for someone who has a higher level of activity and fitness . Because the exercise capacity of adults tends to decrease as they age, older adults generally have lower exercise capacities than younger persons. Thus, they need a physical activity plan that is of lower absolute intensity and amount than is appropriate for more fit people, especially when they have been sedentary and are starting an activity program.Low Intensity (up to 80% MHR)
This has the effect of improving general fitness and improves the muscles' ability to use the oxygen delivered to them via the bloodBlood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
. This efficiency is accomplished by increasing the number of capillaries in the muscle.
Medium Intensity (80-85% MHR)
This intensity is around anaerobic threshold (AT) and improves an individual's AT - allowing the body to work at a higher intensity while still working aerobicallyAerobic exercise
Aerobic exercise is physical exercise of relatively low intensity that depends primarily on the aerobic energy-generating process. Aerobic literally means "living in air", and refers to the use of oxygen to adequately meet energy demands during exercise via aerobic metabolism...
.
High Intensity (85-90% MHR)
The heartHeart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
is a muscle and can be trained to become stronger and more efficient. This intensity of exercise places a load on the heart causing it to become stronger so it can pump more blood in one contraction
Muscle contraction
Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...
.
Flat Out (90-100% MHR)
In this region the body works completely anaerobicallyAnaerobic exercise
Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass...
- causing a quick build up of lactate (lactic acid
Lactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...
). This kind of training, despite being very painful, improves the body's anaerobic capacity - the production, removal, and tolerance to lactic acid.