PHYSIOLOGICAL RESPONSES AND ADAPTATION TO EXERCISE GUNGAHLIN COLLEGE Human Movement EXERCISE PHYSIOLOGY (CHRONIC) PHYSIOLOGICAL RESPONSES AND ADAPTATION TO EXERCISE

CHRONIC ADAPTATIONS TO TRAINING Chronic adaptations are known as the SAID principle. Specific Adaptation Imposed Demands. Adaptations are specific to the demands placed on the body, or training methods & principles used.

CHRONIC ADAPTATIONS TO TRAINING Heart Size Stroke Volume (SV) Heart Rate (HR) Cardiac Output (Q) Av02 difference Blood flow & Capillarisation of the heart & skeletal muscle Blood Pressure Pulmonary diffusion at the lungs Minute ventilation VO2 maximum

CHRONIC ADAPTATIONS TO TRAINING Function Heart size Changes The volume of the left ventricle increases with long-term aerobic training. Explanation – A possible explanation for the increase in the LV volume is that there is an ↑ in plasma volume & a ↓ in HR in trained individuals. This causes the walls of the ventricles to expand.

CHRONIC ADAPTATIONS TO TRAINING Function Stroke Volume (SV) Changes Increases Explanation The SV increases due to an ↑ in LV volume & enhanced contractility of the heart. There is also an ↑ in diastolic filling time due to a ↓ in HR.

CHRONIC ADAPTATIONS TO TRAINING Function Heart Rate (HR) Changes Decrease This decrease in HR is called bradychardia. Max HR stays the same or decreases slightly Explanation – The heart rate decreases for trained individuals due to enhanced nervous activity of the heart (McArdle et.al. 2001).

CHRONIC ADAPTATIONS TO TRAINING Function Cardiac Output (Q) Changes Rest: 5L (stays the same) Submax: ↓ or stays the same Max: ↑ This is the most significant cardiovascular change as a result of aerobic training Explanation – Enhanced distribution of blood & ↑ aVO2 difference for trained individuals enables Q to stay the same at rest & sub-maximal intensities. Q increases during maximal exercise due to chronic increases in SV for trained individuals. Q = HR x SV

CHRONIC ADAPTATIONS TO TRAINING See the following examples Rest Untrained: 5000ml = 70 bpm x 71 ml Trained: 5000ml = 50 bpm x 100 ml Maximal Exercise Untrained: 20,000 = 195 bpm x 113 ml Trained: 35,000 = 195 bpm x 179 ml (McArdle et.al. 2001 p347)

CHRONIC ADAPTATIONS TO TRAINING Function AvO2 diff Changes Increases Explanation The capillarisation of muscles, ↑ in haemoglobin concentration, ↑ in the no. of mitochondria & an ↑ oxidative enzymes in trained individuals allows for an increase in aVO2 diff. The ↑ in Q also contributes to ↑s in the aVO2 diff at maximal intensities.

CHRONIC ADAPTATIONS TO TRAINING Function Blood flow & Capillarisation of the heart & skeletal muscle Changes Increases Explanation Trained individuals can distribute larger amounts of blood to the heart and skeletal muscles at submaximal and maximal intensities. This is due to the growth of new capillaries and the increase in the size of the small veins & arteries. Trained individuals increase blood flow to working muscles due to higher Q at maximal intensities.

CHRONIC ADAPTATIONS TO TRAINING Function Blood Pressure (BP) Changes ↓ during rest and submaximal exercise, particularly in sufferers of hypertension. Explanation Trained individuals have a lower BP, particularly systolic BP, due to capillarisation of the heart & muscles and enhanced elasticity of the arteries

CHRONIC ADAPTATIONS TO TRAINING Function Pulmonary diffusion at the lungs Changes Increases Explanation More O2 diffuses into the lungs due to capillarisation surrounding the alveoli & an increase in blood volume in trained individuals.

CHRONIC ADAPTATIONS TO TRAINING Function Minute ventilation Changes ↓ in submaximal activity ↑ in max exercise Explanation At submaximal intensities there is ↑ TV & RR ↓. At maximal intensities both TV & RR ↑.

CHRONIC ADAPTATIONS TO TRAINING See the following examples Rest Average: 6 L.min¯1 = 12 x 0.5 L Maximal Exercise Untrained: 70 L.min¯1 = 35 x 2.0L Trained: 180 L.min¯1 = 45 x 4.0L (McArdle et.al. 2001 p347)

CHRONIC ADAPTATIONS TO TRAINING Function VO2 maximum Changes Rest: Stays same Submax: Stays same Max: ↑ (increases from 15-30% in 3 months & up to 50% in 2 years) Explanation At submaximal intensities, trained and untrained individuals attain similar steady state oxygen consumption values. However, trained individuals reach steady state faster, resulting in smaller O2 deficits. Increases in VO2 at maximal intensities are mostly attributed to increases in maximal SV & Q. The following adaptations also contribute to enhanced VO2 max with training: increases in aVO2 diff, blood volume, capillarisation & VE.

CHRONIC ADAPTATIONS TO TRAINING Function Muscle & Blood Lactate Levels Changes Rest: Stays same 1mMol/kg Submax: ↓ Max: ↑

CHRONIC ADAPTATIONS TO TRAINING Explanation Trained individuals are able to obtain a greater total amount of O2 at submaximal & maximal intensities due to aerobic adaptations. Trained individuals can exchange & remove lactate & H ions from the blood efficiently. This decreases the amounts of lactate & H ions at a given intensity in comparison to untrained individuals. Consequently, trained individuals are able to work at higher intensities before they reach their lactate threshold (Jones et.al.2000 p379, Tomlin et.al 2001 p3). The lactate curve shifts to the right with training.

Parameter Untrained Trained % max HR 60 90 % VO2 max 50 80 Blood lactate 4 mMol  4mMol

CHRONIC ADAPTATIONS TO TRAINING At maximal intensities, higher levels of lactic acid & H ions are produced. Trained individuals achieve higher lactate tolerance. They would also be able to tolerate higher levels of H ions. Lactate levels are able to be measured in the blood & muscles. A higher tolerance to lactic acid also indirectly indicates a higher tolerance to H ions.

CHRONIC ADAPTATIONS TO TRAINING There is an improved capacity to transport lactate & H ions in the skeletal muscle (Pilegaard, H etal. 1999) There is an improved motivation and tolerance to pain with training. No research has shown an increase in the ability to buffer higher amounts of lactic acid with training. Sprint/power athletes can generally tolerate 20-30% higher levels of lactic acid during maximal activity than untrained individuals (McArdle et.al. 2001 p160).

OTHER CHRONIC CHANGES Aerobically trained individuals are able to replenish stored ATP & PC stores faster in recovery than untrained individuals. Aerobically trained individuals are able to oxidise higher levels of lactate & H ions at a faster rate during recovery.

OTHER CHRONIC CHANGES  in body fat levels or stores of adipose tissue under the skin. Optimal levels include: Females 13-25%, males 10-20%. Decreases in body fat levels occur in aerobic programs due to the use of fats as a fuel source for energy during exercise.

OTHER CHRONIC CHANGES Decreases in body fat levels also occur in strength based programs as muscles use more triglycerides at rest due to hypertrophy of muscle.  no. of HDL lipoproteins & a  in LDL lipoproteins, decreasing total cholesterol & cholesterol risk factor for heart disease.