Describing the endurance index for automotive workers: a retrospective study

Khumalo, Thulani
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Introduction: The purpose of this study was to describe the Endurance Index of automotive workers to determine aerobic capacity to sustain an 8 hour shift. The Endurance Index is the product of Work (in Joules) performed by muscles divided by Peak Heart Rate (in beats per minute). Since there is no clear method for determining full work tolerance (8 hour sustenance) for job specific endurance activities, a new scientific method is warranted. Methods: This was a retrospective study and 44 jobs were randomly selected. In those jobs there was a sample of 101 automotive workers (n = 94 males and n = 6 females). From the 44 jobs, there were 220 endurance activities/tests and peak heart rates and total work performed by muscles was described then these variables were used to calculate Endurance Index which was described for each endurance activity. Results: Peak HR had a mean of 139.85 ±20.96 (100 – 184bpm), total work had a mean of 9224.73 ±5826.04 (897.20 – 33 055) and EI had a mean of 67.14 ±42.88 (8 – 243.10). Total work and EI had significant (p < 0.00) and good positive correlation (r = 0.97). Peak HR and EI had significant (p < 0.01) and poor negative correlation (r = -0.18). Conclusion: The scientific rationale for using Endurance Index as an indicator for aerobic capacity is that the better conditioned an individual the more work that can be produced at lower relative heart rates compared to individuals who are poorly conditioned. So the more the work value and the lower the heart rate value, the better the index. In this study it was found that Endurance index is a good indicator of aerobic capacity since a positive correlation was found between total work and Endurance index and a negative correlation was found between peak heart rate during an endurance activity and Endurance Index.
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Science in Medicine in the field of Biokinetics. 21 June 2018
Endurance Index , Aerobic Capacity