Module 2 mcc sports nutrition credit course- physiology of exercise and sport

MODULE 2 - PHYSIOLOGY OF EXERCISE AND SPORT

EFFECT OF TRAINING ON CARDIOVASCULAR 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 them

SYSTOLIC 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.

EFFECT OF TRAINING ON CARDIOVASCULAR SYSTEM

• Heart rate

• Stroke volume

• Cardiac output

• Blood flow

• Blood pressure

• Blood

HEART RATE (HR)

Resting HR Healthy Adults: Averages 60 to 80 beats/min Elite endurance athletes : 28 to 40 beats/min have been recorded.

As you begin to exercise, your heart rate increases proportionately to the intensity of exercise

i.e higher the intensity, the higher your heart rate

Heart 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 system

Exception: 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 Starling's law). The heart rate increases in an attempt to compensate for the lower stroke volume and maintain a constant cardiac output.

STROKE VOLUME

Stroke volume is the amount of blood ejected per beat from left ventricle.

Measured in ml/beat. Stroke Volume - 70 ml/beat

Stroke 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 FLOW

The vascular system can redistribute blood to those tissues with the greatest immediate demand and away from areas that have less demand for oxygen.

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 PRESSURE

At rest: 120/80 mm Hg

RANGES:Systolic blood pressure -110-140mmHg Diastolic blood pressure - 60-90mmHg for

During exercise

Systolic pressure INCREASES to over 200 mmHg Diastolic pressure on the other hand REMAINS RELATIVELY

UNCHANGED regardless of exercise intensity

Resistance Exercise:Higher systolic pressure

Upper 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 TRANSPORT

AT REST:1L arterial blood carries 200 ml oxygen.

Trained / Untrained athletes circulate 5L of blood per minute at rest

therefore, 1000 ml of oxygen become available per minute

a-VO2 DIFFERENCEAt Rest: Oxygen content of blood varies from about 200 ml of oxygen per 1L of arterial blood to 140 ml of oxygen per 1L of venous blood

The 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, the

a-VO2 difference reaches 150 ml / 1L of blood

Effect of training respiratory system.

http://www.youtube.com/watch?v=FyhYHlA7bZw

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 RESULTS REPRESENT MAXIMAL TEST

1. Lactate value > 8mmol/L

2. 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 breath

4. plateau in oxygen consumption

5. Rate of perceived exertion equal or greater than 17

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 84.4

Lance Armstrong, Tour de France Cycling Champion 83.8 Alberto Salazar, world record holder, marathon 78.0 Grete Waitz, world class female distance runner 73.5

CLASS ACTIVITY

Print page from text book -table 5.2 pg 128.

Is it a true VO2 Max test result?

LACTIC ACID THRESHOLD

What is LACTIC ACID?It is formed from glycogen by muscle cells when

the oxygen supply is inadequate to support energy production.

LACTATE THRESHOLD

The 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 production

The lactate threshold for most males is between 165 and 180 beats per minute, with females being slightly higher, at about 175 to 185

beats per minute

LACTATE LEVELS

Normal 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 athletes around 70% to 80% VO2 max.

TRAINING PHASES

Pre Competition • Correct Nutrition Deficiencies if any

• Correct Body Composition

• Improve all aspects of fitness

During Competition • Focus on specific foods

• Hydration

• Recovery

Post Competition - Off season • Revisit body composition

• Eating habits

• Prevent weight gain