Aerobic Exercise

Original Editor - Manisha Shrestha

Top Contributors - Manisha Shrestha, Lucinda hampton, Rubi, Rishika Babburu, Kim Jackson and Candace Goh  

Introduction

Aerobic exercise is one of the type of physical exercise which helps in promoting physical fitness and preventing health illness.Aerobic exercise is defined as any form of physical activity that produces an increased heart rate and respiratory volume to meet the oxygen requirements of the activated muscle.The American College of Sports Medicine (ACSM) defines aerobic exercise as any activity that uses large muscle groups, can be maintained continuously and is rhythmic in nature.

Aerobic exercises are typically moderate-intensity exercises performed to improve one’s cardiorespiratory fitness and in promoting energy expenditure and fat utilization.As the name suggest these kind of exercises depend primarily on aerobic energy- production i.e. muscle groups activated by this type of exercise rely on aerobic metabolism i.e. using oxygen to extract energy in the form of adenosine triphosphate (ATP) from amino acids, carbohydrates and fatty acids.

Examples of aerobic exercise include walking, cycling, swimming, jogging, dancing, hiking, long distance running,etc.

Effects of aerobic exercises

Aerobic exercises mainly shows effect in health related components of fitness especially cardiovascular endurance and body composition. Physiological effects of aerobic exercises are explained below:

1. Heart rate: Resting HR decreases with aerobic training and is lower at any given workload. The maximum HR is unchanged.
2. Cardiac output:Maximum CO increases, whereas resting CO is stable. Resting SV increases, with a corresponding decrease in the resting HR.
3. Aerobic capacity: Maximal aerobic capacity or maximal oxygen uptake (VO2max) is a measure of the maximum amount of oxygen that an individual can use per unit of time during strenuous physical exertion at sea level.Maximum aerobic capacity increases with aerobic training. The resting Vo2 is stable, as is the Vo2 at a given workload. The changes are specific to the trained muscles.
4. Stroke volume: SV increases at rest and is maintained at a lower HR, resulting in a lower RPP for a given level of exertion.
5. Myocardial oxygen capacity: Maximum Mvo2 usually does not change, but at a given workload, Mvo2 decreases with training. This reduces episodes of angina.
6. Peripheral vascular resistance (PVR): Aerobic training reduces arterial and arteriolar tone, thereby decreasing cardiac “afterload” and PVR. The reduction in PVR results in a lower RPP and a lower Mvo2 at a given workload and at rest.

These effects helps in following benefits to the body:

• Higher endurance during intense physical activity because of blood volume increase.
• Lungs volume increase
• Cardiac muscle strength
• HDL level increase (the ratio of total cholesterol to HDL decrease reduces the risk of atherosclerosis)
• Emotional stress overcoming and enhancing mental and emotional well being
• Increase bone density.

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1. Aerobic capacity: Maximum aerobic capacity increases with aerobic training. The resting Vo2 is stable, as is the Vo2 at a given workload. The changes are specific to the trained muscles.
2. Cardiac output: Maximum CO increases, whereas resting CO is stable. Resting SV increases, with a corresponding decrease in the resting HR.
3. Heart rate: Resting HR decreases with aerobic training and is lower at any given workload. The maximum HR is unchanged.
4. Stroke volume: SV increases at rest and is maintained at a lower HR, resulting in a lower RPP for a given level of exertion.
5. Myocardial oxygen capacity: Maximum Mvo2 usually does not change, but at a given workload, Mvo2 decreases with training. This reduces episodes of angina.
6. Peripheral vascular resistance (PVR): Aerobic training reduces arterial and arteriolar tone, thereby decreasing cardiac “afterload” and PVR. The reduction in PVR results in a lower RPP and a lower Mvo2 at a given workload and at rest.

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Criterion measures

Before prescribing or doing any aerobic exercises, it is very necessary to do pre-participation health screening to ensuring exercise training can be safely initiated. It is also important to exercise testing used for diagnostic (i.e., identify abnormal physiologic responses), prognostic (i.e., identify adverse events), and therapeutic (i.e., gauge impact of a given intervention) purposes as well as for physical activity counseling and to design an exercise prescription.

Standard graded exercise tests (GXT) are used clinically to assess a patient’s ability to tolerate increasing intensities of aerobic exercise. Grade treadmill testing,cycle ergometer,arm ergometer are some examples and Bruce treadmill test remains one of the most commonly used protocols in grade treadmill testing. Via these testing, it would help to identify the criterion measures for cardiovascular fitness and exercise capacity.

Maximal aerobic power or maximal oxygen uptake (VO2max): It is a measure of the maximum amount of oxygen that an individual can use per unit of time during strenuous physical exertion at sea level.Maximal aerobic power is typically expressed in absolute power as L/min or normalized for body weight as mL · kg−1 · min−1.It is convenient to express oxygen uptake in multiples of sitting/resting requirements.Peak metabolic equivalents (MET): One metabolic equivalent (MET) is a unit of sitting/resting oxygen uptake (≈3.5 mL of O2 per kilogram of body weight per minute [mL · kg−1 · min−1]). METs are a useful, convenient, and standarized way to describe the absolute intensity of a variety of physical activities. Light physical activity is defined as requiring 3 METs, moderate as 3–6 METs, and vigorous as 6 METs. V̇o2 max is influenced by age, sex, exercise habits, heredity, and cardiovascular clinical status.

Evidences

American College of Sports and Medicine (ACSM), 2014 has prescribed aerobic exercises based on FITT ( frequency, intensity, time, type) in different condition and age groups.

1. cardiovascular disease
2. hypertension
3. weight loss
4. diabetes
5. chronic pain
6. elderly
7. depression

Resources

• (2014) ACSM's guideline for exercise testing and prescription.
• AHA-Exercise Standards for Testing and Training.