ALL questions are based on the following scenario. Please study it carefully and refer to it for ALL questions:

ALL questions are based on the following scenario. Please study it carefully and refer to it for ALL questions:

Mary is a well trained cyclist who trains for, and competes in, a range of endurance cycling events that include one day races lasting 3-4 hr, time trials ranging from 30-60 min, and multistage “tour” events that require prolonged, strenuous exercise on 5-6 consecutive days. Over the course of a year, Mary organizes periods of rest and intense training around her competitive season that occurs in the summer months. As part of the ongoing monitoring of her physiological responses and adaptation, she undergoes regular exercise testing during which her heart rate and blood lactate are measured after a standard cycling exercise test at 200W and periodically she completes an incremental exercise test to exhaustion to measure her maximal oxygen uptake. One of the tour events is often held in hot conditions and Mary schedules a period of training in a hot environment in order to acclimatize to such conditions.

Question 1

During the exercise sessions there is a large increase in skeletal muscle blood flow, which is primarily due to:

increased circulating adrenaline acting on β-receptors

metabolic vasodilators

sympathetic, cholingeric nerve activity

Question 2

In the face of this large increase in skeletal muscle blood flow, mean arterial blood pressure is generally well maintained due to:

cerebral vasoconstriction

increased cardiac output

redistribution of blood volume

Question 3

Following a period of training after her annual break, Mary’s heart rate during the standard exercise test was significantly reduced. The most likely explanation for this is:

enhanced cardiac adrenergic sensitivity

increased stroke volume

lower vagal activity

Question 4

Her maximal oxygen uptake was also increased, primarily due to an increase in:

muscle oxidative capacity

maximal a-v O2 difference

maximal cardiac output

Question 5

Interestingly, during one of the maximal test the consultant physiologist observed slight arterial desaturation at the high exercise intensities. This was most likely due to:

pulmonary diffusion limitation

pulmonary oedema

reduced Hb-O2 affinity

Question 6

During the various exercise sessions, the major stimulus to increase ventilation was:

CO2 flux to the lung

increased plasma adrenaline

elevated body core temperature

Question 7

During one of her training sessions in the heat (~30C and 50% humidity), the major mechanism for heat loss was:

convection

radiation

evaporation of sweat

Question 8

On one occasion during training, Mary was unable to refill her drink bottle and completed the prolonged training session without fluid ingestion. Relative to other training sessions when she consumed fluids, a key physiological difference would have been:

higher heart rate

lower muscle glycogen use

higher stroke volume

Question 9

Often when Mary trained in hot conditions she felt more fatigued and unable to generate the same power output. A potential explanation for this is:

reduced central motor drive to the muscles

muscle glycogen depletion which resulted in premature fatigue

higher blood lactate levels

Question 10

Following a period of training that involved repeated long rides over 6 days in a hot environment (acclimatization), a major adaptation contributing to enhanced physiological function would have been:

expanded blood volume

reduced sweat sensitivity

higher sweat [Na+]

Дата добавления: 2015-11-04