Exercise Physiology

for Health and Sports Performance

Nick Draper, Helen Marshall

• Editore: Routledge
• Anno: 2014
• ISBN:
  9781317902591
• Edizione: 1
• Argomento: Médecine
• Categoria: Physiologie

Exercise Physiology for Health and Sports Performance brings together all the essential human anatomy and applied physiology that students of exercise science, physical education and sports coaching need to know.

Written in a friendly, accessible style and containing a wide range of features to help develop understanding, this book provides a complete one-stop-shop for exercise physiology.

The book is split into two key parts. Part One introduces the fundamental principles of nutrition, biochemistry, cell biology and the energy systems. Part Two builds on this foundation by applying the theory to exercise and sports performance in practice. With this innovative approach, the text enables you to become confident in your knowledge and understanding of energy generation and training principles for all sports. Including coverage of exercise in extreme environments and applications of physical activity for health, this will be the only exercise physiology textbook you will need!

Foundations of exercise physiology

Exercise physiology, sport and pedagogy:
an historical perspective

Learning objectives

After reading, considering and discussing with a study partner the material in this chapter you should be able to:

describe a range of developments regarding our knowledge in the fields of anatomy, physiology and exercise physiology

identify researchers who have made significant contributions to our understanding of contemporary exercise physiology

outline how sport and physical education have changed over the centuries and how this might affect the role of exercise physiologists

be challenged to use a range of teaching pedagogies in your teaching or coaching of exercise physiology

1.1 An historical perspective: the context of contemporary exercise physiology

This section is designed to highlight some of the interesting and significant developments in knowledge that led to our current understanding in the field of exercise physiology. For future physical education teachers, especially those who after graduation might well teach exercise physiology, this section can provide useful examples and contexts through which to bring your teaching sessions alive. For example, until the work of William Harvey (1578–1657), physiologists thought the blood within our bodies ebbed and flowed like the sea, rather than circulated, as he demonstrated through his research. Examples such as these highlight how our knowledge of human functioning has changed over time.

The early physiologists

Perhaps not surprisingly, much of the early work regarding human physiology related to describing the structures within the body (the anatomy) rather than the functioning (the physiology). The Greeks, during the times of the Greek Empire, were responsible for a great number of advances in our early understanding of anatomy and physiology. Greek scholars were very good at assimilating knowledge from other cultures as their empire expanded and they learned from the observations made by scholars in Mesopotamia, Egypt and India. From around 600 BCE to the fall of the Greek Empire to Rome in 201 BCE, Greek scholars, often philosophers at that time, such as Empedocles (495–435 BCE), Hippocrates (460–377 BCE), Plato (427–347 BCE) and Aristotle (384–322 BCE) developed existing physiological knowledge, much of which remained unchallenged for over 1,000 years.

As happens now in the development of our modern physiological knowledge, each generation built upon, or challenged, the accepted theories of the time. Empedocles, in developing his theories of physiological knowledge, viewed the world as comprising various elements that required a balance to be maintained between them. To Empedocles, humans were comprised of four elements: earth, fire, air and water. To maintain health, it was essential to maintain a balance between the four human components. Ill-health was the result of an imbalance between the four elements. The soul, Empedocles maintained, was located in the blood. Hippocrates and his disciples, based on the Island of Cos, wrote many medical papers or ‘treaties’. Hippocrates, through his work in the field of medicine, has become known as the founder of western medicine. Indeed, doctors today still undertake to follow the Hippocratic Oath. Hippocrates and his son-in-law Polybos developed Empedocles’ theories concerning the four components that comprised the human body and referred to them as four antagonist humours (from Greek, chymos meaning juice or fluid). These humours were black bile (earth), yellow bile (fire), blood (air) and phlegm (water), a balance between each being required to maintain health. Figure 1.1 provides an illustration of the relationship between the elements and the humours.

Galen, whose contribution to physiology is discussed in more detail in the next section, went on to link the bodily aspects of the humours to a person’s bodily temperament, which was associated with their personality type and susceptibility to disease. He described these temperaments as warm, cold, moist and dry, such that the humour of blood, as can be seen in Figure 1.1, was associated with warm and moist temperament qualities. Indeed, the personality traits associated with being phlegmatic, sanguine or melancholic originate from Galen’s temperaments.

Figure 1.1 The elements, qualities and humours of the human body according to Hippocratic medicine.

Maintaining a balance between the humours was important for good health and reflected a balanced temperament. In contrast, imbalances between the humours were detrimental to health. It was the influence of humourism that led to the introduction of bloodletting, often using leeches, which remained a common practice amongst physicians for over 1,000 years. It was thought that by releasing fluid from the body the balance between the humours, and therefore good health, could be restored. Interestingly, blood was considered a special element, as it was thought to contain all four humours; blood, black bile, yellow bile and phlegm. In the 1920s a Swedish physiologist Fåhræus, when considering why such a theory might have arisen, examined blood after it was left in an open tray for one hour and found evidence of components within the sample that might have led the early physiologists to such a conclusion. After being left the blood began to separate into layers and to clot. As a result there were red (red blood cells), black (blood clots), yellow (plasma) and white (buffy coat or white blood cells) layers which the early physiologists might have interpreted as evidence of the four humours, blood, black bile, yellow bile and phlegm, respectively.

Hippocrates and his followers believed that the balance between the humours was assisted by the heat provided through an internal fire, that was maintained in the bloodless left ventricle of the heart. To maintain the internal fire, life-giving air or pneuma, along with food and drink for nourishment, was required. All food and drink was made up of blood, bile (black and yellow) and phlegm. It was at this time that the theory of blood ebbing and flowing was developed by the followers of Hippocrates. Through simple dissections, largely of animals, the early physiologists determined, mistakenly, that blood ebbed and flowed rather than circulated and only entered the right side of the heart. The left side of the heart was associated with the internal fire of life. The left auricle of the heart received pneuma on each inspiration, which was supplied to the left ventricle to help nourish the internal fire. The heat created by the internal fire was believed to be responsible for the beating of the heart.

Plato’s view of physiology differed little from those of Hippocrates and Aristotle, although he saw t...