An Investigation Of The Association Between Perceived Exertion And Heart Rate During Aerobic Training In Individuals Post-Stroke
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The addition of aerobic exercise to standard rehabilitation can improve functional outcomes and reduce the chance of secondary stroke. Measurement of exercise intensity can be difficult in clinical practice due to lack of specialised equipment often resulting in insufficient intensities to induce cardiopulmonary strain. Intensity may be assessed by proxy measures such as the Borg Scale of Rate of Perceived Exertion (RPE). However, there is a lack of research investigating the relationship between the Borg RPE scale and objective measures of exercise intensity such as heart rate reserve in the stroke population.
Aims and Objectives
The primary aim of this research was to investigate whether there was a relationship
between perceived exertion and heart rate in a sub-acute stroke population during aerobic exercise.
The secondary aim was to determine whether guiding exercise intensity using the Borg RPE scale,
was an effective way of achieving recommended target heart rate reserve (HRR) levels of at least 40%.
A cross-sectional, observational study was undertaken using a sample of convenience.
A total of 23 participants in the sub-acute stage post stroke were recruited from an acute stroke unit.
Participants underwent exercise testing on a lower limb ergometer for 15 minutes with
increasing resistance until their exertion level was rated at 14 on the Borg RPE scale.
Heart rate reserve and Borg levels were recorded at the end of every minute of testing.
Correlation between Borg RPE and heart rate reserve was analysed using a Spearman Rank Correlation.
The level of HRR achieved was analysed descriptively and univariable linear regression
was used to determine the strength of relationship between baseline characteristics
(age, sex, stroke severity, number of medications, number of comorbidities,
smoking history, physical activity prior to stroke and time since stroke) and HRR level achieved.
The mean (SD) age of participants was 67.17 (14.00) years and 61% were male. Mean (SD) NIHSS score was 4.09 (2.88) and median time since stroke was 5.00 (14.00) days. The majority of participants (n=13) achieved a mean HRR between 10%-19%. Five participants achieved a maximum value of > 40% HRR at one-time point during the exercise test. One participant achieved a mean HRR > 40% for the duration of the exercise test. Participants who achieved > 40% HRR had higher physical activity levels prior to stroke, lower stroke severity and carried out the exercise test sooner post-stroke than those who did not achieve >40%HRR. A weak correlation was found between mean HRR and mean Borg RPE values R=0.32 and this was not significant (p
This study found a weak relationship between reported values on the Borg RPE scale and HRR during aerobic exercise, in a sub-acute stroke population. Therefore, the Borg RPE scale does not accurately indicate the level of exercise intensity in the sub-acute stroke population. The results also indicated that use of the Borg RPE scale to rate exertion up to a level of somewhat hard (level 14) during exercise, did not result in the achievement of recommended heart rate reserve levels between 40%-70% HRR.