Your body is a collection of systems that work in synergy to create energy to power physical and mental activities. All of the functions in your body rely on oxygen -- either during the activity in question or immediately afterward. Exercise can be classed as aerobic, which means with oxygen, or anaerobic, which means without oxygen. All forms of exercise place similar short-term demands on the systems of your body.
Bones and Joints
Bones are avascular and have little in the way of oxygen demand or blood supply however still experience short term changes as a result of exercise. Increased joint movement results in short-term increases in synovial fluid. Synovial fluid lubricates and nourishes your joints and helps keep them supple. In the short term, the presence of synovial fluid causes an increase in the range of movement available in your joints and explains why a stiff joint can feel looser during or after exercise.
Muscles
Muscles demand an increased volume of oxygen during exercise. Oxygenated blood is diverted from non-essential organs and muscles to the areas of highest demand. This increase in metabolic activity causes your body temperature to rise, your heart rate to increase and your breathing to speed up. In response to the elevation in temperature, your body secretes sweat via sweat glands to help keep you cool and opens up blood vessels close to your skin's surface so that heat can radiate away from your body.
Heart and Lungs
Increased levels of activity require increased amounts of oxygen carrying blood to be pumped to your working muscles. Without oxygen, the reactions necessary for energy production will quickly cease. Breathing rate and heart rate both increase to ensure that your muscles receive the oxygen they need while you work out. To allow easier blood flow to your working muscles, the blood vessels expand in a process called vasodilation. This is often seen in the reddening of the skin over the working muscles and more visible blood vessels.
Hormones
Hormones are chemical messengers that tell the organs and tissues of your body how to act. During exercise, levels of blood glucose begin to drop and the hormone glucogon is produced. Glucogon triggers the release of glycogen from your liver which is subsequently converted to glucose and then used for fuel by your brain. The hormone adrenalin is produced by your adrenal glands with are located on top of your kidneys. Adrenalin speeds up your heart rate, increases muscle contraction and also causes dilation of your blood vessels for the easy movement of blood. Endorphins, your body's natural mood enhancer and pain killer, are produced during exercise and are responsible for the so-called runner's high experienced by many exercisers.
References
- "ACSM's Resources for the Personal Trainer"; American College of Sports Medicine; 2009
- "Principles of Anatomy & Physiology, Ninth Edition"; Sandra R. Grabowski & Gerald J. Tortora; 2000
- "Anatomy of Exercise: A Trainer's Inside Guide to Your Workout" Pat Manocchia; 2009
- "Applied Anatomy and Biomechancis in Sport - 2nd Edition"; Timothy R. Ackland, Bruce C. Elliott, and John Bloomfield; 2008
