Aerobic Exercise

Original Editor - Manisha Shrestha

Top Contributors - Manisha Shrestha, Lucinda hampton, Rubi and Kim Jackson  

Introduction

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Aerobic exercise refers to the type of repetitive, structured physical activity that requires the body’s metabolic system to use oxygen to produce energy. Aerobic exercise:

  • 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.[1]
  • 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).[1]
  • Examples include walking, cycling, swimming, jogging, dancing, hiking, long distance running.

Effects of aerobic exercises

[2]

Aerobic exercises mainly shows an effect in health-related components of fitness especially cardiovascular endurance and body composition.

For neuromuscular adaptation following aerobic exercises click link.

Physiological effects of aerobic exercises are explained below:[3]

  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.[4]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:[5][6]

  • Higher endurance during intense physical activity because of blood volume increase
  • Lung volume increase
  • Cardiac muscle strength
  • HDL 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.

How Much?

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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[7].

Criterion measures

Why perform exercise tests?

  • To ensure aerobic exercise training can be safely initiated (perform a pre-participation health screening (see link)).
  • 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[8].

These tests help to identify the criterion measures for cardiovascular fitness and exercise capacity.[9]

  • 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. [9] V̇o2 max is influenced by age, sex, exercise habits, heredity, and cardiovascular clinical status.[10]

Evidences

American College of Sports and Medicine (ACSM), 2014 has prescribed aerobic exercises based on FITT ( frequency, intensity, time, type) in different conditions and age groups.[9]

Cardiovascular Disease/ Risk factors and Aerobic Exercise

Cardiovascular diseases (CVDs) are the number one cause of death globally, taking an estimated 17.9 million lives each year. Out of many cardiovascular diseases, heart attack and stroke being the most common cause of death. Lifestyle modification is the first line of treatment suggested by WHO and American heart association which includes diet and exercise.[11] Supervised cardiac rehabilitation protocols are there to guide the treatment.

A randomized controlled trial done in 2019, has shown benefits of combined training (aerobic 30 minutes/session plus resistance 30 minutes/session) 3 days/week for 8 week rather than aerobic exercise and resistance exercise alone. Combined training provided significant reductions in peripheral (-4 mmHg) and central diastolic BP (-4 mmHg), increase in CRF (4.9 ml/kg/min), increase in upper (4 kg) and lower (11 kg) body strength, and increase in lean body mass (0.8 kg).[12]

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.[13]

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. For detail please have a look at this guideline.[13]

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.[14]

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 allows a better night's sleep. alternatively it will help to cope with the demands of pregnancy and birth.[15] A Cochrane systemic review has shown that Regular aerobic exercise during pregnancy appears to improve (or maintain) physical fitness.[16]

A meta-analysis of 9 RCTs 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, lower incidences of GDM, GHTN disorders, cesarean delivery, and a higher rate of vaginal delivery.[17]

Risk of Fall in Elderly and Aerobics:

As the age advances there are various physiological changes occur in the body, hence muscle strength reduces more in lower extremity than the upper extremity, increases the risk of fall in geriatric population. Aerobic exercises has shown improvement in balance and gait.[18]

Resources

References

  1. 1.0 1.1 Patel H, Alkhawam H, Madanieh R, Shah N, Kosmas CE, Vittorio TJ. Aerobic vs anaerobic exercise training effects on the cardiovascular system. World journal of cardiology. 2017 Feb 26;9(2):134.
  2. Dr.James Meschino. Benefits of Aerobic Exercise. Available from: https://www.youtube.com/watch?v=IbIfHDlBoHs [last accessed 5/5/2020]
  3. Cifu DX, Lew HL. Braddom s Rehabilitation Care: A Clinical Handbook E-Book. Elsevier Health Sciences; 2017 Jun 8. (Chapter: Acute medical condition)
  4. Seidenberg P, Beutler AI. The sports medicine resource manual. Elsevier; 2008 Jan 1. (Chapter:Testing for Maximal Aerobic Power)
  5. Blumenthal JA, Emery CF, Madden DJ, George LK, Coleman RE, Riddle MW, McKee DC, Reasoner J, Williams RS. Cardiovascular and behavioral effects of aerobic exercise training in healthy older men and women. Journal of gerontology. 1989 Sep 1;44(5):M147-57.
  6. Niu Y, Zhou D, Ma Z. Effect of aerobic exercises on students’ physical health indicators. Science & Sports. 2018 Apr 1;33(2):e85-9.
  7. Mayoclinic Aerobic exercise Available from:https://www.mayoclinic.org/healthy-lifestyle/fitness/basics/aerobic-exercise/hlv-20049447 (last accessed 23.10.2020)
  8. verywellfit Bruce treadmill test Available from:https://www.verywellfit.com/the-bruce-treadmill-test-protocol-3120269 (last accessed 22.10.2020)
  9. 9.0 9.1 9.2 American College of Sports and Medicine. (2014) ACSM's Guidelines for Exercise Testing and Prescription. Available from: http://antoinedl.com/fichiers/public/ACSM-guidelines-2014.pdf [2020-5-5].
  10. Gerald et al. American heart association. Exercise Standards for Testing and Training. Available from: https://www.ahajournals.org/doi/full/10.1161/hc3901.095960[2020/5/5].
  11. World health organization. Cardiovascular diseases (CVDs). Available from: https://www.who.int/en/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds) [last accessed:2020/5/5].
  12. Schroeder EC, Franke WD, Sharp RL, Lee DC. Comparative effectiveness of aerobic, resistance, and combined training on cardiovascular disease risk factors: a randomized controlled trial. PloS one. 2019;14(1).
  13. 13.0 13.1 Sigal RJ, Armstrong MJ, Bacon SL, Boule NG, Dasgupta K, Kenny GP, Riddell MC. Physical activity and diabetes. Canadian journal of diabetes. 2018 Apr 1;42:S54-63.
  14. Morres ID, Hatzigeorgiadis A, Stathi A, Comoutos N, Arpin‐Cribbie C, Krommidas C, Theodorakis Y. Aerobic exercise for adult patients with major depressive disorder in mental health services: A systematic review and meta‐analysis. Depression and anxiety. 2019 Jan;36(1):39-53.
  15. Hinman SK, Smith KB, Quillen DM, Smith MS. Exercise in pregnancy: a clinical review. Sports health. 2015 Nov;7(6):527-31.
  16. Kramer MS, McDonald SW. Aerobic exercise for women during pregnancy. Cochrane database of systematic reviews. 2006(3).
  17. Di Mascio D, Magro-Malosso ER, Saccone G, Marhefka GD, Berghella V. Exercise during pregnancy in normal-weight women and risk of preterm birth: a systematic review and meta-analysis of randomized controlled trials. American journal of obstetrics and gynecology. 2016 Nov 1;215(5):561-71.
  18. Kulkarni, Shweta & Shaikh, Rahat & Yeole, Ujwal. Effects of Aerobic Exercises on Balance And Gait In Geriatric. Int J Recent Sci Res.2018 Jan 9(1):22878-81.