Heart Rate Monitors

The first wireless heart rate monitor (HRM) was introduced in 1983 and since then many improvements have been made e.g.

Coded transmission process (from chest strap to watch) to reduce interference with other HRMs
Ability to capture large amounts of data
Functions to aid with training e.g. high and low ranges for setting training zones
Ability to download the captured data onto a computer and then analyse with special software
Ability to determine your VO2 max

The use of an HRM to set exercise intensity is based on sound physiological principals - as the work increases, oxygen consumption (VO2) and heart rate increases in a linear relationship until near maximal intensities. Heart rate is easier to measure than oxygen consumption and the relationship between them has been established, however, there is one critical component - knowing your maximum heart rate.

Factors effecting Heart Rate

Many factors can alter your heart rate:

Stress
Illness
Over training
Medication
Time of day
Food and drink (Caffeine)
Altitude
Temperature
Hydration levels
Weather conditions
Heart rate drift
Heart rate variability

Heart rate drift

This is the increase in heart rate seen over time while exercising at a constant workload. Some studies have found that your heart rate can increase by as much as 5 to 20 bpm during exercise lasting 20 to 60 minutes even when the work rate does not change.

Heart rate variability

This describes the variations in the intervals between consecutive heartbeats. Even when the heart rate is stable, the time between consecutive beats can vary considerably. At rest, heart rate variability is larger in aerobically trained individuals than in untrained individuals.

Vagal Tone

The nervous system influences the resting heart rate by means of signals from the Vagus nerve. Resting heart rate will fluctuate with the respiration cycle. Inspiration is accompanied by heart rate elevation and expiration with a drop in heart rate. When there is large variability for each respiratory cycle we say there is a high vagal tone and when there is low variability we have low or poor vagal tone.

Summary

The heart rate is a useful parameter for monitoring the reaction of the athlete's body to training and the HRM provides a convenient method for measuring and recording heart rate during exercise.

Heart rate, on its own, does not allow for an accurate assessment of the training effectiveness over time and cannot tell the coach or athlete which aspects of the training program are having a positive or negative influence on training adaptation.

Page Reference

The reference for this page is:

MACKENZIE, B. (1997) Heart Rate Monitors [WWW] Available from: http://www.brianmac.co.uk/hrm.htm [Accessed

Associated Pages

The following Sports Coach pages should be read in conjunction with this page: