Aerobic respiration usually involves exercises within the air. This activity involves the breakdown of glucose for energy use, but it does not involve oxygen usage. Anaerobic exercise involves exercise without air; it refers to producing energy without using oxygen (Chamari & Padulo, 2015). This essay aims to evaluate the physiological process of both aerobic and anaerobic exercise, along with the process of muscular fatigue. It will also involve the standard measures of assessing the body composition, aerobic and anaerobic power, and capacity.

Main body:

            During aerobic exercise, the body has differential physiological changes. These changes include increased breathing rate, and heartbeat rate becomes fast and more profound. This increases the blood flow in the entire body, especially to the muscles and back to the lungs. Aerobic training enhances the body’s internal functioning. Adaption to aerobic exercise causes metabolic adaptations in the body, increasing the number and size of mitochondria (powerhouse). Also, it enhances the activity of the oxidative enzymes, intratriglycerides stores and myoglobin concentration (Spurway, 2015). Alterations also occur in the muscle fibre types. Other changes include pulmonary adaptations, blood lactate concentration, body composition changes, and improved thermoregulation. The body composition changes include the increased fat-free mass or the decreased fat mass (Patel et al., 2017). Increased fat-free mass is at the level of initially untrained exercise. Blood lactate concentration causes decreased production, increased clearance, and greater tolerance. Decreased production due to aerobic respiration associates with the need to recruit type 2 fibres. The increased clearance increase enzyme activity (LDH) and buffering capacity (Skinner & Mclellan, 2010).

            In the case of anaerobic exercise, the body responds differently. This exercise improves the rate of ATP utilization and resynthesis. The increase in the intramuscular concentrations does not increase by a more significant amount and limits in between the percentage of 5 to 30%. Simultaneously, the increase in the muscular CSA depends on the anaerobic activity carried out (Romer & Polkey, 2008). Besides this, the concentration and the enzymes increase from a longer internal work. Other physiological activities that increase include PFK activity, LDH activity, P.K. activity, C.K. activity, and A.K. activity. Anaerobic exercise also improves lactate tolerance, and in this case, La is achieved by increased tolerance, substrate availability, enzyme activity and buffering capacity. The buffering capacity range falls between 20-50% for the equivalent muscle pH. This is all about the physiological changes (Patel et al., 2017).

            Furthermore, both aerobic and anaerobic exercise causes muscle fatigue. Muscle fatigue is defined as the failure to maintain the expected output power in the body after exercise. Fatigue associates with different reasons in different cases, and it does not always contribute to the accumulation of lactic acid (Green, 1997). Another reason for muscle fatigue is due to the reason that ATP regeneration rate is not equal to that of the ATP utilization rate. The process of fatigue occurs due to the interruption of the chain of events between the central nervous system and the muscle fibre. Possible stages of muscle fatigue in the body includes spinal cord, peripheral nerve, sarcolemma, transverse tubular system, calcium ion release, actin-myosin interaction, cross bridge tension and heat and the last stage is of the power output. Muscular fatigue involves motivation (motor unit recruitment), neuromuscular transmission, muscle action potential, excitation, and activation. Energy supply is also involved in the activation process (Enoka & Stuart, 1992).

            Different standard measures are used to measure the body composition, aerobic and anaerobic power, and capacity. These physiological parameters involve both the lab and field tests like gold standard tests. Field tests are mostly used because they have higher external validity. Measurement principles include reliability, validity, specificity and practicality. Anaerobic measures include different physiological measures based on the relative exercises as VO2, H.R., RER, [La]. Measures of different analysis are also involved in it, like muscle biopsies, immediate freezing, and assessment of [ATP], [PCr] and [La]. This analysis reflects that both anaerobic power and capacity includes an estimation of measuring the external power output. The vertical jump test is another standard, and its measures the power capacity using the formula Power (W) = 21.67 x Mass(kg) x Height(m)0.5. Another testing involved here is isometric testing and is a gold standard of isometric testing. Field assessment, goniometer, Leighton flexometer, and the sit and reach test. All these standard measures have a higher validity rate and effectively assess body composition and power (Goodpaster et al., 2006).


            To conclude, the body responds differently to both exercises and make adaptations accordingly. Aerobic exercise involves several metabolic adaptations like enhanced muscular activity and oxidative enzymes (Spurway, 2015). While anaerobic exercise involves the improve rate of ATP utilization and resynthesis. Both these exercise cause muscle fatigue in the body. This might involved impaired blood flow and accumulation of lactic acid (Sahlin et al., 1998). Different standard measures are also discussed above.


Chamari, K. and Padulo, J., 2015. ‘Aerobic’and ‘Anaerobic’terms used in exercise physiology: a critical terminology reflection. Sports medicine-open1(1), pp.1-4.

Enoka, R.M. and Stuart, D.G., 1992. Neurobiology of muscle fatigue. Journal of applied physiology72(5), pp.1631-1648.

Goodpaster, B.H., Park, S.W., Harris, T.B., Kritchevsky, S.B., Nevitt, M., Schwartz, A.V., Simonsick, E.M., Tylavsky, F.A., Visser, M. and Newman, A.B., 2006. The loss of skeletal muscle strength, mass, and quality in older adults: the health, aging and body composition study. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences61(10), pp.1059-1064.

Green, H.J., 1997. Mechanisms of muscle fatigue in intense exercise. Journal of sports sciences15(3), pp.247-256.

Patel, H., Alkhawam, H., Madanieh, R., Shah, N., Kosmas, C.E. and Vittorio, T.J., 2017. Aerobic vs anaerobic exercise training effects on the cardiovascular system. World journal of cardiology9(2), p.134.

Romer, L.M. and Polkey, M.I., 2008. Exercise-induced respiratory muscle fatigue: implications for performance. Journal of Applied Physiology104(3), pp.879-888.

Sahlin, K., Tonkonogi, M. and Söderlund, K., 1998. Energy supply and muscle fatigue in humans. Acta Physiologica Scandinavica162(3), pp.261-266.

Skinner, J.S. and Mclellan, T.H., 2010. The transition from aerobic to anaerobic metabolism. Research quarterly for exercise and sport51(1), pp.234-248.

Spurway, N.C., 2015. Aerobic exercise, anaerobic exercise and the lactate threshold. British Medical Bulletin48(3), pp.569-591.

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