Module 2 mcc sports nutrition credit course- physiology of exercise and sport
MODULE 2 -PHYSIOLOGY OFEXERCISE AND SPORT
EFFECT OF TRAINING ONCARDIOVASCULAR AND RESPIRATORY SYSTEM
Blood pressure is the amount of force (pressure) that blood exerts on the walls of the blood vessels as it passes through themSYSTOLIC BP: (ventricular contraction)When your heart beats, it contracts and pushes blood through the arteries to the rest of your body. This force creates pressure on the arteries.A normal systolic blood pressure is below 120.DIASTOLIC BP: The diastolic blood pressure number or the bottom number indicates the pressure in the arteries when the heart rests between beats. A normal diastolic blood pressure number is less than 80.
HEART RATE (HR)Resting HR Healthy Adults:Averages 60 to 80 beats/minElite endurance athletes :28 to 40 beats/minhave been recorded.As you begin to exercise, your heart rate increases proportionately to the intensity of exercisei.e higher the intensity, the higher your heart rateHeart rate increases in direct proportion to exercise intensity until a maximum heart rate is reached.
STEADY STATE HEART RATE:Although heart rate increases rapidly with the onset of activity, providing exercise intensity remains constant, heart rate will level off. This is known as steady-state heart rate where the demands of the active tissues can be adequately met by the cardiovascular systemException:In a hot climate, a steady-state heart rate will gradually increase. This phenomenon is known as cardiac drift.The cardiovascular drift is associated with sweating and a redistribution of blood so that peripheral circulation is increased. Body fluids are lost, reducing the volume of blood returning to the heart causing a decrease in stroke volume (see Starlings law). The heart rate increases in an attempt to compensate for the lower stroke volume and maintain a constant cardiac output.
STROKE VOLUMEStroke volume is the amount of blood ejected per beat from left ventricle.Measured in ml/beat.Stroke Volume - 70 ml/beatStroke volume increases proportionally with exercise intensity.
STROKE VOLUME INCREASES• Intrinsic to myocardium, involves enhanced cardiac filling in diastole, followed by more powerful systolic contraction.• Neuro Hormonal influence: Normal ventricular with subsequent formal ejection and emptying during systole• Training adaptations that expand blood volume and reduce resistance to blood flow in peripheral tissues
CARDIAC OUTPUT During exercise both heart rate and stroke volume increase which results in an increase in cardiac output. Most significant indicator of circulatory system to meet the demands for physical activity Cardiac output [Q ] = Stroke volume * Heart rate At rest the cardiac output is about 5L/min During intense exercise- 20-40L/min
BLOOD FLOWThe vascular system can redistribute blood tothose tissues with the greatest immediate demandand away from areas that have less demand foroxygen. REST - 5 L EXERCISE - 25 L Liver - 27% Liver - 2% Kidneys - 22 % Kidneys - 1% Muscles - 20% Muscles - 84% Skin - 6% Skin - 2% Brain - 14% Brain - 14% Others - 7% Others - 3%
BLOOD PRESSUREAt rest: 120/80 mm HgRANGES:Systolic blood pressure -110-140mmHgDiastolic blood pressure - 60-90mmHg forDuring exerciseSystolic pressure INCREASES to over 200 mmHgDiastolic pressure on the other hand REMAINS RELATIVELY UNCHANGED regardless of exercise intensity
Resistance Exercise:Higher systolic pressureUpper Body Exercise:SBP and DBP increases substantially as smaller arm muscle mass and vasculature offer greater ressistance to blood flow than more larger and vascularized lower- body regions.
BLOOD & OXYGEN TRANSPORTAT REST:1L arterial blood carries 200 ml oxygen.Trained / Untrained athletes circulate 5L of blood per minute at resttherefore, 1000 ml of oxygen become available per minute
a-VO2 DIFFERENCEAt Rest: Oxygen content of blood varies from about200 ml of oxygen per 1L of arterial bloodto 140 ml of oxygen per 1L of venous bloodThe difference in oxygen content of arterial and venous blood is known as a-VO2 difference.Exercise:Capacity of each 1L of arterial blood to carry oxygen increases during exercise.At rest, the a- VO2 difference is approximately 50 ml of O2 for every 1L of blood ; as the rate of work approaches maximal levels, thea-VO2 difference reaches 150 ml / 1L of blood
Effect of training respiratory system.http://www.youtube.com/watch?v=FyhYHlA7bZ w
MAXIMAL OXYGEN UPTAKE(VO2 MAX )The highest amount of oxygen an individual can take in, transport and utilize to produce ATP aerobically while breathing air during heavy exercise.
CRITERIA TO TEST IF TEST RESULTSREPRESENT MAXIMAL TEST1. Lactate value > 8mmol/L2. A heart rate +/- 12 beats/min of predicted maximal heart rate (220 - age)3. A respiratory exchange ratio of 1.0 or 1.1The ratio between the amount of CO2 exhaled and O2 inhaled in one breath4. plateau in oxygen consumption
NOTES:As our bodies perform strenuous exercise, we begin to breathe faster as we attempt to shuttle more oxygen to our working muscles. The body prefers to generate most of its energy using aerobic methods, meaning with oxygen. Some circumstances, however, --such as evading the historical saber tooth tiger or lifting heavy weights--require energy production faster than our bodies can adequately deliver oxygen. In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate through a series of steps. When the body has plenty of oxygen, pyruvate is shuttled to an aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown--and thus energy production--to continue. The working muscle cells can continue this type of anaerobic energy production at high rates for one to three minutes, during which time lactate can accumulate to high levels
VO2max values of some athletes (ml/kg/min):Steve Prefontaine, middle distance runner, American record holder 84.4Lance Armstrong, Tour de France Cycling Champion 83.8Alberto Salazar, world record holder, marathon 78.0Grete Waitz, world class female distance runner 73.5
CLASS ACTIVITYPrint page from text book -table 5.2 pg 128.Is it a true VO2 Max test result?
LACTIC ACID THRESHOLDWhat is LACTIC ACID?It is formed from glycogen by muscle cells when the oxygen supply is inadequate to support energy production.
LACTATE THRESHOLDThe point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate productionThe lactate threshold for most males is between 165 and 180 beats per minute, with females being slightly higher, at about 175 to 185beats per minute
LACTATE LEVELSNormal amount of lactic acid circulating in the blood is about 1 to 2 millimoles/litre of blood.The onset of blood lactate accumulation (OBLA)occurs between 2 and 4 millimoles/litre of blood.In non athletes this point is about 50% to 60% VO2 max and in trained athletesaround 70% to 80% VO2 max.
Pre Competition• Correct Nutrition Deficiencies if any• Correct Body Composition• Improve all aspects of fitnessDuring Competition• Focus on specific foods• Hydration• RecoveryPost Competition - Off season• Revisit body composition• Eating habits• Prevent weight gain