In view of the current lockdown, it has become necessary to modify and adapt regular exercise programs from outdoor to home conditions, taking advantage of both the space and material available. It is of the utmost importance to follow the recommendations of scientific societies, health institutions and experts. Maintaining physical activity levels is key to addressing sedentary behavior as well as to mitigating the psychological impact of quarantine, since sedentariness has a well known detrimental effect on cardiovascular function.
Regular aerobic activity, such as walking, bicycling or swimming, can help you live longer and healthier. Need motivation? Examine the effects of aerobic exercise on your pulse, lungs, and blood flow. Then get moving and start reaping the rewards.
Aerobic exercise refers to the type of repetitive, structured physical activity that requires the body’s metabolic system to use oxygen to produce energy.
● Improves the capacity of the cardiovascular system to uptake and transport oxygen.
● Can be undertaken in many different forms, with the common feature that it is achieved at a heart rate of 70–80% of a person’s age-appropriate maximum.
● Considered the cornerstone of endurance training, characterized by moderate energy expenditure over a prolonged period of time.
● Is any activity that uses large muscle groups, can be maintained continuously and is rhythmic in nature.
● Depends primarily on aerobic energy- production i.e. muscle groups activated by this type of exercise rely on aerobic metabolism (using oxygen to extract energy in the form of adenosine triphosphate (ATP) from amino acids, carbohydrates and fatty acids).
● Examples include walking, cycling, swimming, jogging, dancing, hiking, long distance running.
Effects of aerobic exercises
Aerobic exercises mainly show an effect in health-related components of fitness especially cardiovascular endurance and body composition.
Physiological effects of aerobic exercises are explained below:
Heart rate: Resting HR decreases with aerobic training and is lower at any given workload. The maximum HR (heart rate) is unchanged.
Cardiac output: Maximum Cardiac output increases, whereas resting Cardiac output is stable. Resting Stroke Volume increases, with a corresponding decrease in the resting HR.
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.
Stroke volume: SV increases at rest and is maintained at a lower HR, resulting in a lower RPP (Rate Pressure Product) for a given level of exertion.
Myocardial oxygen capacity: Maximum Mvo2 usually does not change, but at a given workload, Mvo2 decreases with training. This reduces episodes of angina.
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.
● Lung volume increase
● Cardiac muscle strength
● HDL (high density lipo-protein) level increase (the ratio of total cholesterol to HDL decrease reduces the risk of atherosclerosis)
● Overcoming and enhancing mental and emotional well being.
● Increase bone density.
Healthy adults should aim for at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity a week, or an equivalent combination of moderate and vigorous activity. That doesn’t have to be all at one time, though. For example, brisk walking for 30 minutes, five days a week meets the guidelines. Aerobic exercise can even be done in short blocks of time, such as several walk breaks spread throughout the day. Any activity is better than none at all.
Why perform exercise tests?
● Diagnostic reasons — to identify abnormal physiologic responses
● Prognostic reasons — to identify adverse events
● Therapeutic reasons — to gauge the impact of a given intervention; physical activity counseling; to design an exercise prescription.
Standard graded exercise tests are used clinically to assess a patient’s ability to tolerate increasing intensities of aerobic exercise Eg:
- Cycle ergometer
- Bruce treadmill test (one of the most commonly used protocols in grade treadmill testing) — A maximal exercise test where the athlete works to complete exhaustion as the treadmill speed and incline is increased every three minutes. The length of time on the treadmill is the test score and can be used to estimate the VO2 max value. During the test, heart rate, blood pressure, and ratings of perceived exertion are often also collected.
These tests 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 standardized 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.
Diabetes and Aerobic Exercise
Supervised exercise interventions improve glycated hemoglobin (A1C), triglycerides (TG), and cholesterol (9) in people with type 2 diabetes. Both aerobic and resistance exercise are beneficial, and it is optimal to do both types of exercise. At least 150 minutes per week of aerobic exercise and at least 2 sessions per week of resistance exercise are recommended.
It is very important to maintain the dose of insulin and time of exercise and also carbohydrate intake during and after exercise to prevent post-exercise hypoglycemia.
Chronic pain and Aerobic Exercises
Aerobic exercise programs have shown physiological, psychological, and articular benefits in patients with chronic diseases (e.g., arthritis, osteoarthritis, and fibromyalgia). Aerobic exercise stimulates the release of endorphins that relieve pain by inhibiting the pain pathways. It makes the patient more active, reducing the fear of moving (kinesiophobia) and increasing self-confidence.
A systematic review protocol published in 2019 has shown the effect of aerobic exercise and chronic non- specific low back pain. Aerobic exercise with a duration of 15 to 60 continuous minutes and intensity of 60 to 90% of the maximum heart rate had shown significant improvement.
Mental health and Aerobic Exercise
In the systematic review and meta-analysis done in 2019 across 11 eligible trials (13 comparisons) involving 455 patients, aerobic exercise delivered for an average of 45 minutes, at moderate intensity, three times/week, for 9.2 weeks and showed a significantly large overall antidepressant effect.
Pregnancy and Aerobics
Low impact aerobic exercises are the key to physiological as well as psychological well-being during pregnancy. Regular, low-impact aerobic exercise during pregnancy will help to strengthen heart and lungs, to tone muscles, ease pregnancy aches and pains and allow a better night’s sleep. alternatively it will help to cope with the demands of pregnancy and birth. A general systematic review has shown that Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness.
A meta-analysis of 9 RCTs (Randomized Controlled trial) that included 2059 women with an uncomplicated, singleton pregnancy with normal body mass index showed that women who were assigned randomly to aerobic exercise had similar incidence of PTB (pulmonary tuberculosis), lower incidences of GDM (Gestational Diabetes), GHTN (Gestational hypertension) disorders, cesarean delivery, and a higher rate of vaginal delivery.
There is irrefutable evidence of the beneficial role of physical exercise in disease prevention, as an adjuvant treatment in chronic diseases, and in psychological wellbeing. Furthermore, exercise could also have a protective effect on the immune system, whose optimal status is crucial to respond adequately to the threat of COVID-19. This is especially important in chronically ill patients. Therefore, it is important to preserve lifestyles and particularly the practice of physical exercise.