The sport discipline

The sport discipline

In sport disciplines that rely on speed endurance or strength endurance anaerobic glycolysis provides the primary energy source for muscular contractions Zajac et al 2009

During high intensity exercise there is an increase of hydrogen H ions in the mitochondria Pilegaard et al 1999 The metabolic demands of highintensity exercise are met primarily by glycolysis which is the nonoxidative breakdown of glucose Gosselink et al1995 This is caused when the demand for energy exceeds oxygen supply or utilisation rate As a result the cell mitochondria cannot process all hydrogen ions joined to its carrier NADH The hydrogen ions begin to accumulate in the cells which decrease the pH of exercising muscles and cellular acidosis occurs Brooks 1985 To maintain availability of NAD and to prevent acidosis excess Hydrogen ions are temporarily bound with pyruvate to form lactic acid

Rupp et al 1983 states that at rest arterial blood pH is 74 while venous blood pH is normally slightly lower 73735 and muscle pH is 69 It is also suggested Exhaustive exercise decreases pH 04 pH units in both blood and muscle and is highly correlated to increased blood lactate concentration Similarly blood and muscle bicarbonate ion concentration decreases linearly as a function of increasing lactate ion concentration

This increase in hydrogen ion concentration interferes with anaerobic metabolism by disrupting the activities of key enzymes it is also associated with reduction in ATP production lipolysis and muscle tension Monedero Donne 2000

Harrison and Thompson 2005 state that the increase in acidity ultimately inhibits energy transfer and the ability of the muscles to contract forcing the athlete to decrease the intensity of exercise Gollnick et al 1986 suggests that this is because hydrogen ions displace calcium from troponin which causes interference in muscle contraction It is the production of these hydrogen ions and the decrease in pH that causes the effects associated with fatigue Robergs 2004

Acidemia also has an effect on the cardiovascular system by reducing or stops the responses of the heart to stimulation of sympathetic nerves and slows the heart rate due to vagal stimulation Hainsworth 1986

CO2 levels and the pH of the blood perfusing the cephalic circulation has an effect on efferent signal activity Soladoye et al 1985

The bodys first line of defence to prevent acidemia are naturally occurring chemical buffers such as a weak carbonic acid and sodium bicarbonates Zajac et al 2009

A buffer is a solution containing substances which have the ability to minimise changes in pH when an acid or base is added to it worthley 1977

The intracellular buffering system includes amino acids proteins Pi HCO3 creatine phosphate CrP hydrolysis and lactate production binds or consumes H to protect the cell against intracellular proton accumulation Robergs et al 2004

Explain gradient

In the bicarbonate buffer HCO3 system the chemical equilibrium between carbonic acid and bicarbonate act as a ph regulator Buffering results in H ions being drawn out from the muscle cells into the blood due to a concentration gradient This process reduces the acidity within in the muscle cells Lambert et al 1993 If the H in blood begins to drop then the pH raises more carbonic acid dissociates replenishing hydrogen ions When H rises the bicarbonate ion acts as a base and removes the excess hydrogen ions lowering the pH Mcnaughton et al 2008

During buffering NaHCO3 in plasma exerts a strong buffering action on lactic acid to form sodium lactate and carbonic acid An additional increase in H from carbonic acid dissociation causes the dissociation reaction to move in the opposite direction to release carbon dioxide into plasma McArdle et al 2007

Hydrogen ions carbon dioxide and oxygen are detected by specialized chemoreceptors in the brain Inside cells carbon dioxide CO2 combines with water H2O to form carbonic acid H2CO3 The carbonic acid breaks down ra

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