Physiology & Psychology: Cardiovascular Factors

Facts

The heart rate (HR) is one of the simplest and most informative of the cardiovascular parameters. Measuring it involves simply taking the subject's pulse, usually at the radial or carotid site. Heart rate reflects the amount of work the heart must do to meet the increased demands of the body when engaged in cross-country skiing. To understand this, we must compare the heart rate at rest and during exercise.

Resting Heart Rate

Resting heart rate averages 60 to 80 beats per minute. In middle-aged, unconditioned, sedentary individuals the resting rate can exceed 100 beats per minute. In highly conditioned endurance-trained athletes, such as Olympic cross-country skiers, resting rates in the range of 28 to 40 beats per minute have been reported. Your resting heart rate typically de-creases with age. It is also affected by environmental factors; for example, it increases with extremes in temperature and altitude.

The heart of a normal individual beats re-flexively about 40 million times a year. During this time, over 4000 gallons, or 10 tons, of blood are circulated each day, and every night the heart's workload is equivalent to a person carrying a thirty-pound pack to the top of the 10 -story Empire State Building.

Before the start of exercise, your pre-exercise heart rate usually increases well above normal resting values. This is called an anticipatory response. This response is mediated through release of the neurotrans-mitter norepinephrine from your sympathetic nervous system, and the hormone epinephrine from your adre-nal gland. Because the pre-exercise heart rate is elevated, reliable esti-mates of actual resting heart rate should be made only under conditions of total relaxation, such as early in the morning before arising from a restful night's sleep. Pre-exercise heart rates should not be used as estimates of resting heart rate.

The average individual has a resting heart rate between seventy and eighty beats per minute, whereas it is not uncommon for an Olympic cross-country skier's pulse to be in the low fifties or even in the forties.

To measure resting heart rate, take your pulse just after waking in the morning. The pulse should be taken while you are in a sitting or lying position. A range of 50-100 beats per minute for resting heart rate has been established as normal by the American Heart Association. However, research shows that adults with a resting heart rate over 70 have a greater risk of heart attack than those below 70.

Always take the resting heart rate under the same conditions. these conditions include:

Rest from vigorous work or exercise for previous four hours.
Do not eat for two hours prior to taking pulse.
Sit or lie down for at least the previous 30 minutes

NOTE: An ideal time to take the pulse is immediately after waking from a night's sleep.

Take the resting heart rate for five days. Add the five resting heart rates and divide by five to obtain an average.

Day 1_________________
Day 2_________________
Day 3_________________
Day 4_________________
Day 5_________________ divided by 5 = __________________ Resting Heart Rate

To measure the exercise heart rate, do the following:

Record resting heart rate ____________ beats per minute.
Take pulse for 10 seconds and multiply by 6 = _________. Compare with resting pulse.
Warm-up by doing five minutes of stretching exercises. Take pulse for 10 seconds and record _______.
Walk fast for 440 yards. Take pulse for 10 seconds and record __________.
Jog slowly for 440 yards. Take pulse for 10 seconds and record __________.
Run for 440 yards. Take pulse for 10 seconds and record __________.
Complete cool-down by doing stretching exercises. Record heart rate five minutes after cool-down.

The heart of a normal individual beats ereflexively about 40 million times a year. During this time, over 4000 gallons, or 10 tons, of blood are circulated each day, and every night the heart's workload is equivalent to a person carrying a thirty pound pack to the top of the 102 story Empire state Building.

Before the start of exercise, your pre-exercise heart rate usually increases well above normal resting values. This is called an anticipatory response. this response is mediated through release of the neurotransmitter norepinephrine from your sympathetic nervous system, and the hormone epinephrine from your adrenal gland. Because the pre-exercise heart rate is elevated, reliable estimates of actual resting heart rate should be make only under conditions of total relaxation, such as early in the morning before arising from a restful night's sleep. Pre-exercise heart rates should not be used as estimates of resting heart rate.