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Exercise Physiology – Manual

Introduction

This program simulates some of the important physiological measurements which can be made to assess the cardio-respiratory performance of human subjects in the laboratory. The results presented are those from healthy individuals performing graded exercise on a bicycle ergometer and include:

• Heart rate
• Minute ventilation
• Oxygenconsumption
• Blood lactate

Results from the first three of these parameters are presented on a simulated chart recorder. For the blood lactate experiment a simulated spectrophotometer is used.

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The Investigations

You may investigate the effects of graded exercise on a number of physiological parameters.

• Heart rate
• Pulmonary (minute) ventilation
• Oxygenconsumption
• Blood lactate concentration

The effect of exercise differs according to the subjects physical characteristics, sex, age and level of physical fitness which may be enhanced by training. It is therefore important to define a number of subject parameters before you begin the investigation.

Define a subject

You should enter details of sex (male or female), weight in kg,height in cm, age in years and whether you wish your subject to be trained (yes) or untrained (no).

NOTE: In this program training refers to endurance training. In order to illustrate differences in cardio-respiratory fitness between trained and untrained individuals the results for trained subjects are those from highly trained individuals.


Heart Rate

Heart rate results are presented onan animated screen display which simulates a chart recorder. Initially the pre-exercise heart rate is shown and the workload (0 watts) is indicated. The investigation is started, i.e. the subject is made to work. Immediately a work load of 20 watts is indicated on the screen and the clock is started. The increase in heart rate associated with this load is displayed on the chart recorder. Thesubject works at this load for 1 minute when the work load is further increased by another 20 watts. This continues until the subject reaches exhaustion when the experiment is terminated.


Taking Measurements

It is advisable to measure the steady-state heart rate (where the trace levels off) for EACH work load, though this may not be possible particularly at higher work loads. You can then plota graph of heart rate against work load for different subjects, determine the maximum heart rate and compare for example, male with female, trained with untrained individuals, etc.


Minute Ventilation (VE)

Results for minute ventilation (l/min) are displayed in the same way as for heart rate. You should measure the VE for each work load, determine the maximum VE and plot a graph of VEagainst work load for different subjects.


Oxygen Consumption (VO2)

Values for oxygen consumption (l/min) are again displayed on a simulated chart recorder. You should measure the VO2 at different work loads and the maximum VO2 for each subject studied. If the VO2 levels off at high work loads this is known as the VO2 max and is considered to be a measure of aerobic power.


Blood LactateMeasurement of blood lactate levels during exercise can indicate when aerobic metabolism in muscle cells is supplemented by anaerobic mechanisms. You will need to:

a) Collect Samples

Repeat the heart rate experiment and briefly consider where and how many capillary blood samples you would collect from the subject for spectrophotometric analysis. Nine blood samples are collected automaticallyfor you during the experiment. A control (pre-exercise sample) is taken automatically at the start of the experiment. Seven more are taken at regular intervals during the experiment and one immediately after the subject becomes exhausted.


b) Standard Curve

Lactate concentration can be measured using a spectrophotometer. The sample is mixed with certain reagents which react to give a...