Exercise/Sports Physiology

Learning Objectives

• Definitions- i. Aerobic vs. anaerobicii. Isometric vs. Isotoniciii. Acute response vs. exercise training• Sk muscle- ATP synthesis pathwayAerobic exercise training Anaerobic exercise training

• Motor and Autonomic control• CVS- B.P; HR; CO; VR; Flow redistribution;

training.• RS- Ventillation; Oxygen extraction; EPOC;

Training

Exercise Classification

Energy System Time Course1. Adenosine

triphosphate–creatine phosphate system;phosphagen sys : 8 – 10 s

2. Glycogen Lactic acid system: 0.5- 2.5 min

3. Oxidative phosphorylation: hrs

Which of the following sources can produce the greatest amount of ATP per minute over a short period of time?

A) Aerobic systemB) Phosphagen systemC) Glycogen-lactic acid systemD) Phosphocreatine systemE) Stored ATP

Which of the following athletes is able to exercise the longest before exhaustion occurs?A) One on a high-fat dietB) One on a high-carbohydrate dietC) One on a mixed carbohydrate–fat dietD) One on a high-protein dietE) One on a mixed protein–fat diet

Most of the energy for strenuous exercise that lasts for more than 5 to 10 seconds but less than 1 to 2 minutes comes from which of the following sources?

A) Adenosine triphosphate (ATP)B) Anaerobic glycolysisC) Oxidation of carbohydratesD) Oxidation of lactic acidE) Conversion of lactic acid into pyruvic acid

Effect of diet on the rate of muscle glycogen replenishment after prolonged exercise.

Effect of duration of exercise as well as type of diet on relative percentages of carbohydrate or fat used for energy by muscles:

Aerobic exercise training Anaerobic exercise training

1. Energy stores: increase in myocyte gly-cogen stores.

2. Metabolism: increases mitochondrial size and numbers and increase in myoglobin content

1. Hypertrophy: increase in the cross-sectional area of type IIa and IIx muscle fibers by adding new myofibrils to the myocytes.

2.Neural recruitment:3. Metabolism and energy

stores:

Effects of training on muscle mass and performance.

MOTOR AND AUTONOMIC CONTROL

Peripheral Nervous System

• Alpha-Motor neurons:• Motor units:• Muscle sensors: Mus spindle, Golgi tendon

organs, Mus afferents• Cardiovascular receptors

Central nervous system

1. Somatic: The premotor cortex, supplemental motor cortex, and basal ganglia aid in motor program development. This motor program is then executed by the primary motor cortex and signaled via the corticospinal tract. The cerebellum coordinates leg and foot move-ments d

2. Autonomic: Autonomic systems are required to redistribute flow. This is accomplished via sympathetic feedforward and feedback pathways

3. Senses:

• Vision plays a major role in pro-viding information about potential obstacles and the nature of the terrain.

• Hearing plays a lesser role, but it does help provide clues about the location of other riders, gearing, and under-the-tire terrain.

• The vestibular system provides information regarding linear acceleration (otolith organs) and head position when scanning the path ahead and looking for items on either side of the path.

CARDIOVASCULAR SYSTEM

Arterial Pressure

Cardiac Output

Heart RateStroke VolumeVenous return

Flow redistribution

Cardiac adaptation to long term training

Aerobic• Volume-induced cardiac hyper

trophy. • This type of hypertrophy

increases both the LV chamber diameter and LV wall mass and likely is caused by the high venous return and preload accompanying exercise.

• This adap tation increases resting EDV and SV.

Anaerobic• Anaerobic exercise training,

which involves repeatedly forcing the LV to eject against an elevated MAP, stimulates a LV hypertrophy.

• Such hypertrophy is charac-terized by an increase in LV wall thickness but a decrease in lumen diameter.

Vascular adaptation to long term training

• Training increases the ability of skeletal and cardiac muscle to vasodilate, probably through increased nitric oxide pro-duction.

• Over time, angiogenesis increases capillary density and, thereby, decreases the distance for diffusional exchange of O2 and nutrients between blood and myocytes.

• Which of the following parameters is decreased during moderate exercise?

(A) Arteriovenous O2 difference(B) Heart rate(C) Cardiac output(D) Pulse pressure(E) Total peripheral resistance (TPR)

Q. During exercise, total peripheral resistance (TPR) decreases because of the effect of

(A) the sympathetic nervous system on splanchnic arterioles(B) the parasympathetic nervous system on skeletal muscle arterioles(C) local metabolites on skeletal muscle arterioles(D) local metabolites on cerebral arterioles(E) histamine on skeletal muscle arterioles.

Q. During exercise, there is an increase in a person’sa. Stroke volumeb. Diastolic pressurec. Venous complianced. Pulmonary arterial resistancee. Total peripheral resistance

Olympic athletes who run marathons or perform cross countryskiing have much higher maximum cardiac outputs than non-

athletes. Which of the following statements about the hearts of these athletes compared to non-athletes is most accurate?

A) Stroke volume in the Olympic athletes is about 5% greater at rest

B) Percentage increase in heart rate during maximal exercise is much greater in the Olympic athletes

C) Maximum cardiac output is only 3% to 4% greater in the Olympic athletes

D) Resting heart rate in the Olympic athletes is significantlyhigher

RESPIRATORY SYSTEM

Ventilation

Oxygen extraction

Excess postexercise oxygen consumption

Training

1. Ventilation: Maximal alveolar ventilation and VE both increase.

2. Arteriovenous oxygen difference increase: decreased diffusional distance between blood and myocytes due to increased capillary density, and increased blood flow ,Hb also increases .

3. Oxygen uptake:

The increase in CO, alveolar ventilation, and a-v O2 difference combine to increase maximal O2 uptake during training.

Which of the following statements about respiration inexercise is most accurate?

A) Maximum oxygen consumption of a male marathon runner is less than that of an untrained average male

B) Maximum oxygen consumption can be increased about 100% by training

C) Maximum oxygen diffusing capacity of a male marathon runner is much greater than that of an untrained average male

D) Blood levels of oxygen and carbon dioxide are abnormal during exercise