Recovery of rescuers from a 24-h shift and its association with aerobic fitness

Abstract

Objectives: Rescuers work in 24-h shifts and the demanding nature of the occupation requires adequate recovery between work shifts. The purpose of this study has been to find out what kind of changes in autonomic control may be seen during work shift and its recovery period in the case of rescuers. An additional interest has been to see if aerobic fitness is associated with recovery from work shifts. Material and Methods: Fourteen male rescuers (aged 34±9 years old) volunteered to participate in the study. Heart rate variability (HRV) was recorded for 96 h to study stress and recovery, from the beginning of a 24-h work shift to the beginning of the next shift. Aerobic fitness assessment included maximal oxygen uptake (VO 2max ) estimation with a submaximal bicycle ergometer test. Salivary cortisol samples were collected 0 min, 15 min, and 30 min after awakening on the 3 resting days. Results: Some HRV parameters showed enhanced autonomic control after the work shift. Stress percentage decreased from the working day to the 2nd rest day (p < 0.05). However, maximal oxygen uptake was not associated with enhanced parasympathetic cardiac control (p > 0.05). Cortisol awakening response was attenuated right after the work shift. Conclusions: The HRV findings show that recovery after a long work shift takes several days. Thus, rescuers should pay attention to sufficient recovery before the next work shift, and an integrated model of perceived and physiological measurements could be beneficial to assess cardiovascular strain among rescuers with long work shifts.

Are our nurses healthy? Cardiorespiratory fitness in a very exhausting profession

“…Apropos CRF examination in other professions, Khazraee et al (19) studied a group of 115 fire-fighting personnel, but the average age in this group was 32 years and thus we could not compare the results with our group. The same was true for Lyytikäinen et al (20) who studied rescuers (average age 34, VO 2 max 51 mL/kg/min). Kettunen et al (21) did a submaximal exercise testing with an estimation of VO 2 max in a group of 371 workers.…”

Relationships Between Heart Rate Variability, Occupational Performance, and Fitness for Tactical Personnel: A Systematic Review

“…Three of the four were cohort study designs (36,41,42), and one was quasi-experimental (30). Three (30,42), including the experimental study (36), found significant relationships between one or more HRV values and aerobic fitness, and one did not (41). The study finding no significant relationship examined only the LF/HF ratio and SDNN HRV indices.…”

“…A total of four studies examined the relationship between one or more HRV metrics and aerobic fitness (VO 2max ) (30,36,41,42). Three of the four were cohort study designs (36,41,42), and one was quasi-experimental (30).…”

“…A total of four studies examined the relationship between one or more HRV metrics and aerobic fitness (VO 2max ) (30,36,41,42). Three of the four were cohort study designs (36,41,42), and one was quasi-experimental (30). Three (30,42), including the experimental study (36), found significant relationships between one or more HRV values and aerobic fitness, and one did not (41).…”

“…The study finding no significant relationship examined only the LF/HF ratio and SDNN HRV indices. Of the studies reporting significant relationships, LF/HF ratio (36,41), sample entropy, PNN50, and RMSSD were examined. The pooled mean VO 2max across all four studies was 45.4 ± 6.2 ml/kg/min, with the lowest VO 2max in the cohort of off-duty male Brazilian firefighters (40.0 ml/kg/min) (30) and the highest in the cohort of male Brazilian peacekeepers (52.9 ml/kg/min) (36).…”