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Updated: May 26, 2026

A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Cardiorespiratory fitness selection standard and occupational outcomes in trainee firefighters
1Durham and Darlington Fire and Rescue Service, Occupational Health Service, County Hall, Durham DH1 5UY, UK. philip.wynn@durham.gov.uk
Background:
UK fire services have differing practices relating to the use of a cardiorespiratory fitness standard as a selection criterion for recruits.
Aims:
To establish whether a reduction in, or elimination of, a defined cardiorespiratory standard for firefighter recruitment impacted on a number of occupational and health-related outcomes.
Methods:
Data were collected on firefighter recruits from services which applied either a minimum recruit cardiorespiratory fitness standard of 42 ml O(2)/kg/min (398 full-time and 48 part-time recruits) or no such direct standard (198 full-time and 206 part-time subjects). VO(2) max estimated, where available, was also recorded and the impact of a reduction in the standard from 45 to 42 ml O(2)/kg/min assessed.
Results:
Twenty-five per cent of all recruits reported injury during training. Injury-related restrictions were more likely where no cardiorespiratory standard was applied for full-time recruits. For part-time recruits, higher VO(2) max (est.) predicted a lower incidence of injuries. Further adverse health-related outcomes were found for full-time and part-time recruits. Multiple regression analyses suggest that eliminating the 42 ml O(2)/kg/min cardiorespiratory standard at recruitment for full-time firefighters was associated with an 8% (95% CI 7.16-8.84) increase in subsequent injuries reported during training. For part-time firefighters, VO(2) max (est.) was inversely associated with 5% of the variation in injuries (95% CI 4.66-5.34).
Conclusions:
Removal of a cardiorespiratory fitness standard was associated with adverse health and employment outcomes. Older age and gender were not associated with adverse outcomes. No reliable evidence of adverse outcomes from a reduction in a cardiorespiratory standard from 45 to 42 ml O(2)/kg/min was found.
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