Original Editor - Nadja Thöner Show
Top Contributors - Wendy Walker, Lucinda hampton, Tarina van der Stockt, Admin, Kim Jackson, Ewa Jaraczewska, Tony Lowe, Michelle Lee, Chelsea Mclene, Nikhil Benhur Abburi, Evan Thomas, Naomi O'Reilly, Shaimaa Eldib, Rucha Gadgil and Wanda van Niekerk Introduction[edit | edit source]Compared to our resting state, exercise poses a substantial increase in demand for the body.
Function[edit | edit source]Exercise has been shown to have many health benefits. Through functional exercise, we can see benefits in but not limited to:
Through a properly executed exercise program, the body adapts and becomes more efficient at performing various exercises.[1] These adaptations are acute and/or chronic 1. Acute Adaptations to Exercise[edit | edit source]Cardiovascular Responses[edit | edit source]To accommodate the increased metabolic activity in skeletal muscle, the circulatory system must properly control the transport of oxygen and carbon dioxide, as well as help to buffer the pH level of active tissues.
1. Cardiac Output (Q)[edit | edit source]
VO2 is the consumption of oxygen and can be explained by the Fick equation. This equation states that VO2 = [CardiacOutput] x [Difference in arterial and venous oxygen levels]. VO2max is a measure of aerobic exercise capacity and is defined as the highest rate of oxygen uptake an individual can maintain during intense activity.[1]
The 4-minute video below explains the A-V02 difference Blood flow is preferentially shunted away from the gastrointestinal (GI) and renal systems and toward active muscles through the selective constriction and dilation of capillary beds with increasing physical stress,[1]
2. Blood Pressure[edit | edit source]There is a linear increase in systolic blood pressure to peak values of 200 to 249 mmHg in normotensive individuals, and the diastolic pressure value remains near rest level.
Two to three hours post-exercise blood pressure drops below pre-exercising values, this is known as "post-exercise hypotension". 3. Coronary Circulation[edit | edit source]Coronary arteries supply the myocardium with blood and nutrients; on average one capillary supplies one myocardial fibre in the ventricular walls and papillary muscles.[3] Pulmonary System Adaptations[edit | edit source]Pulmonary ventilation is initiated via the respiratory centre in the brainstem with parallel activation through the motor cortical drive that activates skeletal muscles and afferent Type III-IV muscle afferent fibres. The respiratory system works in junction with the cardiovascular system. The pulmonary circuit receives almost all of the cardiac output. In response to the increased cardiac output, perfusion increases in the apex of each lung, increasing the available surface area for gas exchange (decreased alveolar dead space). Maximum exercise training ventilation rates in normal-sized healthy people may increase by a factor of ten, compared to ventilation rates at rest Musculoskeletal System[edit | edit source]There are 3 types of muscle fibers which have different characteristics. Type-I fibres are known as slow-twitch fibres. These fibres have abundant mitochondria and myoglobin with great vascular supply.
Type-IIa fibres are known as fast-twitch oxidative fibres.
Type-IIa fibres can be considered as the middle-ground type of fibre, between the slow but fatigue-resistant type-I fibres and the fast but fatigue-prone type-IIb fibres. Type IIb fibres are known as fast-twitch glycolytic fibres.
With the introduction of progressively overloading exercise training, we can expect skeletal muscle fibres to hypertrophy meaning they increase in diameter and volume.
Resistance Exercise[edit | edit source]Dynamic training and strength training differ primarily in the fact that resistance training produces a vigorous increase in peripheral vascular resistance.
Skeletal Muscle Fibre Type[edit | edit source]The type of physical exercise being undertaken determines the predominant muscle fibre type. Endurance Training ( regular)[edit | edit source]
Hormonal Responses to Exercise[edit | edit source]Endocrine System[edit | edit source]Plasma levels of cortisol, epinephrine, norepinephrine, and dopamine increase with maximal exercise and return to baseline after rest.
Immunological Adjustments[edit | edit source]Moderate training enhances some components of the immune system and thereby reduces the susceptibility to infections. In contrast, reduced functionality of immune cells occurs after overstraining. 2. Chronic Adaptations of Exercise[edit | edit source]Skeletal Muscle Adaptations[edit | edit source]1. Endurance Training[edit | edit source]Slow-twitch fibres: The cross-sectional area of slow-twitch (AKA red) fibres increases slightly in response to aerobic work. Fast-twitch fibres: These fibres develop a higher oxygen capacity. Capillary bed density: Trained muscles possess a higher density of capillaries than untrained muscle, which permits a greater blood flow with increased delivery of nutrients. 2. Resistance/ strength Training[edit | edit source]Resistance training causes increased muscle size (hypertrophy) through an increase of myofibril size and the number of fast- and slow-twitch fibres. Moreover, the recruitment pathway of muscle fibres become more effective. Resistance training thus leads to greater force development of the trained muscles. Ligament and Tendon Adaptations[edit | edit source]There is an increase in the cross-sectional area of ligaments and tendons in response to prolonged training, as the insertion sites between ligaments and bones and tendons and bones become stronger. Metabolic Adaptations of Prolonged Exercise[edit | edit source]Endurance training:
Long Term Cardiac Adaptations[edit | edit source]When healthy individuals participate in a long term aerobic exercise programme they undergo positive cardiac adaptions, both morphologically and physiological.
Stroke volume increases through long term endurance training.
High blood pressure = systolic blood pressure ≥140 and/or diastolic blood pressure ≥90 mm Hg blood pressure. The positive correlation of blood pressure and cardiovascular disease (CVD) risk starts from 115 mm Hg systolic and 75 mm Hg diastolic and doubles with every 20 mm Hg systolic and 10 mm Hg diastolic increase. According to the American College of Sports medicine, dynamic aerobic training reduces blood pressure (BP) in individuals with hypertension.
Long Term Respiratory Adaptations[edit | edit source]The blood flow in the upper regions of the lungs increases after prolonged endurance training and the respiration rate increases. Absolute Contraindications to Exercise[edit | edit source]Unstable Cardiovascular Disease (peripheral and central):[6][7] acute myocardial infarction or unstable angina until stable for at least 5 days, dyspnoea at rest, pericarditis, myocarditis, endocarditis, symptomatic aortic stenosis, cardiomyopathy, unstable or acute heart failure, uncontrolled tachycardia.
Precautions with Exercise[edit | edit source]
Adverse Effects[edit | edit source]Musculoskeletal Adverse Effects[edit | edit source]Sudden force development or repetitive movements can lead to musculoskeletal strain, tear or fracture. Cardiovascular Events[edit | edit source]In an epidemiological study, the Prevalence of Sudden Cardiac Arrest (SCA) was studied between 2002-2013 and was compared with medical data in the USA.
Another study investigated the US National Registry of Sudden Death in Athletes. They found
References[edit | edit source]
What is hyperplasia in resistance training?Historically, two primary mechanisms—hypertrophy and hyperplasia—have been proposed to explain how an increase in the size of an intact muscle might occur. Hypertrophy refers to an increase in the size of individual muscle fibers, whereas hyperplasia refers to an increase in the number of muscle fibers.
Does resistance training cause hyperplasia?In short, no; skeletal muscle hyperplasia is not a myth. Some believe that it does not occur in humans since we don't really have solid evidence of it occurring during a controlled resistance training protocol.
Does hyperplasia increase muscle size?Skeletal muscle enlargement in adult animals has been ascribed primarily to changes in fiber cross-sectional area (i.e., fiber hypertrophy); however, recent evidence from several laboratories suggests strongly that fiber hyperplasia contributes to muscle mass increases in adult animals and possibly human athletes.
Does hyperplasia occur in response to strength training?Hypertrophy and hyperplasia are two prolix words that refer to how muscles grow. Specifically, hypertrophy occurs when muscle cells get bigger, and hyperplasia occurs when the number of muscle cells increases. Countless studies show that hypertrophy occurs in humans, normally as a result of lifting weights.
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