Heart Rate as a Measure of Exercise Testing Early after Acquired Brain Injury

Abstract

Background

The relationship between heart rate and oxygen consumption (VO2) in individuals with acquired brain injury has been described as being curvilinear; which could lead to under-estimation of exercise intensity when prescribed by heart rate.

Purpose

This study examines the linearity of the heart rate/oxygen consumption relationship during incremental cycle ergometer exercise in individuals early after brain injury and provides an estimate of the intra-individual reliability of the heart rate response.

Method

A convenience sample of 38 individuals attending an inpatient neurological rehabilitation centre after acquired brain injury who met the inclusion criteria (trauma 18, stroke 9, tumour and hypoxia 11) underwent testing. Oxygen consumption and heart rate were measured during a graded cycle ergometer test. A further six individuals underwent re-testing within one week

Results

The heart rate/ oxygen consumption response was linear and can be described by the equation:

HR = 86 + 0.029 VO2( SE; 0.003).

Heart rate during the second test was on average

8 beats per minutelower than in the first test.

The random error during the final stage of testing was

8 and 17 beats per minute respectively.

Conclusions

The linear relationship between heart rate and oxygen consumption suggests that exercise intensity can be validly prescribed from heart rate in this group and within the scale range used in this study. The reduced heart rate in individuals re-tested within ten days suggests some bias and that clinicians may need to consider more familiarisation periods before exercise testing. Reliability of exercise testing in this clinical group needs further investigation.

Paper adds to the growing body of evidence that children can acquire phonological systems before they are able to master the phonetic skills needed to convey the contrasts in that system