TY - JOUR
AU - Trudeau,, F
AB - Abstract Background Few fire departments in Québec have a diversified health promotion programme. Yet, many allow firefighters to physically train during working hours. Aims To compare the weekly physical activity (PA) level and cardiovascular health indicators of firefighters who physically train on duty to those who do not. Methods Participants underwent a cardiovascular health assessment and completed an online questionnaire. Results One hundred and five full-time male firefighters participated in the study. Two groups were formed: firefighters who physically train while on duty (E, n = 64) and firefighters who do not (NoE, n = 41). Following statistical adjustments, off-duty weekly PA was not different between the two groups (E: 239 ± 224 versus NoE: 269 ± 249 min, P = 0.496); however, total weekly PA was higher (P = 0.035) in E (381 ± 288 min) than in NoE (274 ± 200 min). A difference was also observed in obesity prevalence measured with waist circumference (E: 9% versus NoE: 27%, P = 0.026) and in physical inactivity prevalence (E: 0% versus NoE: 27%, P < 0.001). After statistical adjustments, E firefighters have a significantly lower waist-to-height ratio than NoE firefighters (E: 0.51 ± 0.05 versus NoE: 0.54 ± 0.05, P = 0.017). Conclusions Results show that firefighters who physically train while on duty have a higher total PA level on a weekly basis and have better cardiovascular health indicators. Our findings suggest that fire services should promote physical training while on duty to improve firefighters’ cardiovascular health. Cardiovascular disease risk, firefighter, health promotion, obesity, physical activity Key learning points What is already known about this subject: Sudden cardiac death accounts for almost half of all on-duty fatalities in firefighters. Diversified worksite health promotion programmes appear to be the most effective for improving the cardiovascular health of emergency service personnel. Few fire departments have a diversified health promotion programme, but many allow firefighters to physically train during working hours, a simple practice that could be effective to improve their cardiovascular health. What this study adds: Off-duty physical activity level is similar in firefighters who physically train on duty and those who do not. Firefighters who physically train while on duty accumulate a higher total physical activity level on a weekly basis and have better cardiovascular health indicators. What impact this may have on practice or policy: Fire services should allow and promote physical training at work for all firefighters, and physical training at work should be part of health promotion programmes to improve firefighters’ cardiovascular health and general work efficacy. Introduction Physical demands, heat stress, dehydration, psychological stress and smoke exposure are part of firefighting and frequently result in high cardiovascular strain [1]. Several physiological mechanisms can trigger cardiac events, particularly in firefighters with underlying diseases [1]. Indeed, a high prevalence of cardiovascular disease (CVD) risk factors is observed in firefighters [2,3], thus increasing the risk of on-duty sudden cardiac death (SCD) [1]. Fahy et al. [4] recently reported that SCD accounts for almost half of all on-duty fatalities in American firefighters. Fire departments should help firefighters adopt and maintain a healthy lifestyle and thereby reduce CVD risk and related problems such as physical disability and the risk of on-duty SCD [1]. This could be implemented through health promotion programmes that include physical training, nutrition education, psychological support, etc. Wolkow et al. [5] reported that combined interventions appear to be the most effective for improving the cardiovascular health of emergency service personnel. In the sole experimental study on worksite health promotion programmes for firefighters, Elliot et al. [6] focused on nutrition, physical activity (PA) and maintenance of body weight (BW) compared with medical follow-up only. They observed that intervention groups had gained weight at the 1-year follow-up, but less than the control group; no improvement was observed in cardiorespiratory fitness. At the 4-year follow-up, most differences between intervention and control groups had disappeared [7]. However, the positive trajectory of healthy behaviours for all groups across time suggests that the programme remained beneficial >3 years after termination of the interventions. A systematic review [8] reported that studies on wellness programmes at firefighter workplaces are scarce, but show some promising results, including high satisfaction with programmes and promising changes in individual behaviours. The International Association of Fire Fighters (IAFF) and the International Association of Fire Chiefs (IAFC) developed The Fire Service Joint Labor Management Wellness-Fitness Initiative (WFI) in 2008 [9], a specific health promotion programme for firefighters. In a cross-sectional study, Poston et al. [10] reported that firefighters from departments with WFI had healthier body composition and a higher cardiorespiratory fitness and PA level than firefighters in departments without the programme. To our knowledge, however, few fire departments in Québec have an official health promotion programme. However, many allow firefighters to physically train during working hours. On-duty physical exercise in fire stations could help heighten PA level on a weekly basis and improve cardiovascular health, as, respectively, 70% and 62% of male and female firefighters do not meet the recommendations of the American College of Sports Medicine (ACSM) in terms of PA [2,3]. Williams [11] reported a significant dose–response relationship between PA level and the risk of coronary artery disease, independently of cardiorespiratory fitness. Using a cross-sectional design, this study aimed to compare the PA level and cardiovascular health of firefighters who physically train on duty in a fire station (E) versus those who do not (NoE) based on a sample of fire departments recruited from across Québec. Methods A total of 760 full-time firefighters from six different municipal fire departments were invited to participate in the study through a recruitment e-mail sent by their respective chief. In Québec, all full-time regular firefighters, lieutenants/captains and officers have the same regular work schedule from the Syndicat des pompiers et pompières du Québec (Firefighters Union of Québec) [12] except for chiefs that were not included in the study. For every 4-week cycle, the schedule consists of six day shifts (07.00 a.m. to 05:00 p.m.), six non-day shifts (05:00 p.m. to 07:00 a.m.) and one 24-h shift, for an average of 42 h per week. However, firefighters often work overtime as a firefighter or in another occupation. The study was approved by the institutional ethics committee of the Université du Québec à Trois-Rivières, and informed consent was obtained from all participants. Participants underwent a physical health assessment, either on-duty at their station or off-duty at a research laboratory. Resting heart rate (HR), brachial blood pressure (BP), height, BW, waist circumference (WC), total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) were measured. They also completed individually an online questionnaire (SurveyMonkey®). Items in the questionnaire included age, gender, rank, PA, smoking status, diabetes, psychological stress, nutrition and information about overtime. All those variables were compared between firefighters who physically train on duty with those who do not. HR was averaged on a 5-min sitting resting period after a 5-min sitting resting period with each participant wearing a RS800CX Polar® chest belt (Kempele, Finland). Data were analysed using Polar ProTrainer 5 software. Resting systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured four times: twice on the right arm and twice on the left arm after a 5-min sitting resting period. All four SBP and DBP were averaged. A manual sphygmomanometer (Welch Allyn, Skaneateles Falls, NY, USA) and a Littmann lightweight stethoscope (3M Health Care, St. Paul, MN, USA) were used for measurements, in accordance with the 2013 guidelines of the Canadian Society of Exercise Physiology (CSEP) [13]. Participants on antihypertensive medication or with SBP or DBP higher than or equal to 140 or 90 mmHg, respectively, were declared to have hypertension [14]. Height, WC and BW (Tanita, Body Composition Analyzer BF-350, Japan) were measured. WC was measured following the CSEP guidelines [13]. Body mass index (BMI), defined as weight in kilograms divided by the square of height in metres (kg/m2), was calculated. WC-obesity corresponded to a WC higher than 102 cm and BMI-obesity corresponded to a BMI equal to or higher than 30 kg/m2 [14]. TC and HDL-C were obtained from fingertip and analysed (CardioChek PA, PTS Diagnostics, Whitestown, IN, USA). Participants on lipid-lowering medication or with HDL-C lower than 1.04 mmol/L were declared to have dyslipidaemia. The off- and on-duty moderate- and high-intensity PA level was estimated based on questions assessing frequency and mean time of PA periods in a typical week. Moderate (3–5.9 metabolic equivalent of task (METs)) (resistance training, brisk walking, household tasks of moderate and vigorous effort) and high (6 METs and more) (jogging, ice hockey, soccer, bicycling, circuit training) intensity levels were determined according to ACSM [14]. An illustrative compendium of PAs was used to identify instances of moderate- and high-intensity PAs [15]. Participants who did not participate in at least 30 min of moderate-intensity PA on at least 3 days/week were declared physically inactive [14]. Participants who did not participate in at least 150 min of moderate or 75 min of high intensity did not meet the World Health Organization (WHO) PA recommendations [16]. Participants were considered smokers if they were current smokers or had quit within the previous 6 months [14]. Participants were considered to have type 2 diabetes (T2D) if they answered ‘yes’ to the question ‘Have you been diagnosed with type 2 diabetes?’ Chronic psychological stress was assessed by the 14-item French version [17] of the Perceived Stress Scale [18]. This questionnaire measures the individuals’ perception of their lives as being unpredictable, overloaded and uncontrollable, using a 5-point Likert-like response scale ranging from ‘never’ to ‘very often’. Intake of vegetables and fruit (fresh, cooked, canned, frozen) (servings/day), red/processed meat (servings/week) and sweet drinks (soft drinks, fruit juice, fruit-flavoured drinks) (servings/week) was quantified. Serving size was established based on the 2007 recommendations of Health Canada [19]. A serving size of vegetables and fruits, red/processed meat and sweet drinks was 125 mL (½ cup). Alcohol consumption was quantified (servings/week) and serving size was established based on the 2018 recommendations of Éduc’alcool [20], a Québec private, independent and non-profit organization that develops prevention, education and information programmes to help adults make informed and responsible decisions about alcohol use. Prevalence comparisons between groups were made using chi-square tests, while independent t-tests were used for continuous variables without (Model A) and with (Model B) statistical adjustment for covariates (ANCOVA). These covariates were age (continuous variable), length of service (continuous), occupational rank (dummy binary variables), whether they worked at least 1 h in an occupation outside the fire department (dichotomous variable) and whether they worked at least one additional hour at the fire department (dichotomous variable). This statistical adjustment was done to limit the effect of these covariates on PA level and cardiovascular health indicators. Non-normal distributions were transformed to near-normality before analysis, values being then retransformed to display means and standard deviations (SDs) in the tables. Pearson partial correlations were calculated for specific parameters. For one participant, the HDL-C value was set at the maximal value of 2.59 that the apparatus could measure. Statistics were performed with IBM SPSS Statistics 20 (Chicago, IL, USA) and Microsoft Excel 2007 (Redmond, WA, USA). All data are presented as means ± SD. Cohen’s effect size (d) was calculated for group comparisons, this index allowed afterwards the post hoc estimation of statistical power. Statistical significance was considered at P ≤ 0.05. Results One hundred and five (E, n = 64; NoE, n = 41) full-time male firefighters participated in the study, representing 14% of the 760 full-time firefighters invited through the recruitment e-mail. Descriptive data are presented in Table 1. Sixty-eight (68) participants were regular firefighters, 31 were lieutenants/captains and 6 were officers. They worked in 19 fire stations, including 11 stations with training facilities and 8 without. Sixty-one (61) firefighters had a second occupation outside the fire department, and 56 firefighters generally worked at least one overtime hour per week in the fire department. Prevalence of BMI-obesity, WC-obesity, smoking, hypertension, dyslipidaemia, physical inactivity and T2D was, respectively, 22, 16, 4, 11, 11, 11 and 0%. Table 1. Descriptive data of participants Variable . Mean ± SD . Median . Range . Age (years) 40 ± 9 40 24–60 Height (cm) 176.2 ± 6.4 176.5 159.1–191.3 BW (kg) 86.1 ± 9.7 84.0 66.7–116.8 BMI (kg/m2) 27.7 ± 2.9 27.5 21.8–38.5 WC (cm) 92.8 ± 8.4 90.4 76.1–115.8 WHtR 0.53 ± 0.05 0.52 0.44–0.66 SBP (mmHg) 119 ± 11 119 98–150 DBP (mmHg) 76 ± 8 76 56–97 HR (bpm) 66 ± 9 66 47–89 TC (mmol/L) 5.16 ± 0.87 5.17 3.47–7.19 HDL-C (mmol/L) 1.54 ± 0.39 1.53 0.55 – 2.59 TC/HDL-C 3.60 ± 1.18 3.32 1.73–7.20 Variable . Mean ± SD . Median . Range . Age (years) 40 ± 9 40 24–60 Height (cm) 176.2 ± 6.4 176.5 159.1–191.3 BW (kg) 86.1 ± 9.7 84.0 66.7–116.8 BMI (kg/m2) 27.7 ± 2.9 27.5 21.8–38.5 WC (cm) 92.8 ± 8.4 90.4 76.1–115.8 WHtR 0.53 ± 0.05 0.52 0.44–0.66 SBP (mmHg) 119 ± 11 119 98–150 DBP (mmHg) 76 ± 8 76 56–97 HR (bpm) 66 ± 9 66 47–89 TC (mmol/L) 5.16 ± 0.87 5.17 3.47–7.19 HDL-C (mmol/L) 1.54 ± 0.39 1.53 0.55 – 2.59 TC/HDL-C 3.60 ± 1.18 3.32 1.73–7.20 HR: 5-min sitting resting heart rate. n = 101 for SBP and DBP (participants on antihypertensive medication were excluded). n = 102 for TC and HDL-C (participants on lipid-lowering medication were excluded). Open in new tab Table 1. Descriptive data of participants Variable . Mean ± SD . Median . Range . Age (years) 40 ± 9 40 24–60 Height (cm) 176.2 ± 6.4 176.5 159.1–191.3 BW (kg) 86.1 ± 9.7 84.0 66.7–116.8 BMI (kg/m2) 27.7 ± 2.9 27.5 21.8–38.5 WC (cm) 92.8 ± 8.4 90.4 76.1–115.8 WHtR 0.53 ± 0.05 0.52 0.44–0.66 SBP (mmHg) 119 ± 11 119 98–150 DBP (mmHg) 76 ± 8 76 56–97 HR (bpm) 66 ± 9 66 47–89 TC (mmol/L) 5.16 ± 0.87 5.17 3.47–7.19 HDL-C (mmol/L) 1.54 ± 0.39 1.53 0.55 – 2.59 TC/HDL-C 3.60 ± 1.18 3.32 1.73–7.20 Variable . Mean ± SD . Median . Range . Age (years) 40 ± 9 40 24–60 Height (cm) 176.2 ± 6.4 176.5 159.1–191.3 BW (kg) 86.1 ± 9.7 84.0 66.7–116.8 BMI (kg/m2) 27.7 ± 2.9 27.5 21.8–38.5 WC (cm) 92.8 ± 8.4 90.4 76.1–115.8 WHtR 0.53 ± 0.05 0.52 0.44–0.66 SBP (mmHg) 119 ± 11 119 98–150 DBP (mmHg) 76 ± 8 76 56–97 HR (bpm) 66 ± 9 66 47–89 TC (mmol/L) 5.16 ± 0.87 5.17 3.47–7.19 HDL-C (mmol/L) 1.54 ± 0.39 1.53 0.55 – 2.59 TC/HDL-C 3.60 ± 1.18 3.32 1.73–7.20 HR: 5-min sitting resting heart rate. n = 101 for SBP and DBP (participants on antihypertensive medication were excluded). n = 102 for TC and HDL-C (participants on lipid-lowering medication were excluded). Open in new tab The E group exercised on duty an average of 74 ± 56 min/week and 34 ± 42 min/week at moderate and high intensity, respectively, for a total of 115 ± 82 min/week. Table 2 shows comparisons of the off-duty and total PA level between E and NoE. A significant difference (P < 0.001) was observed for physical inactivity prevalence between E (0%) and NoE (27%). However, no difference was observed between the proportion of firefighters that did not meet the WHO PA recommendations (E: 11%, NoE: 24%, P = 0.091). A significantly (P < 0.001) higher proportion of E (78%) had access to a training gym (resistance and aerobic training equipment) in their station compared with NoE (27%). Table 2. Comparison between E and NoE regarding PA level Variable . Model . E . NoE . P . d . Off-duty PA at moderate intensity (min/week) A 123 ± 144 147 ± 168 0.390 0.17 B 123 ± 143 149 ± 169 0.340 0.19 Off-duty PA at high intensity (min/week) A 90 ± 113 73 ± 97 0.353 0.19 B 87 ± 111 76 ± 101 0.564 0.12 Off-duty PA total (min/week) A 242 ± 226 263 ± 242 0.626 0.09 B 239 ± 224 270 ± 250 0.484 0.14 Total PA at moderate intensity (min/week) A 216 ± 197 151 ± 146 0.041 0.41 B 214 ± 196 153 ± 149 0.057 0.39 Total PA at high intensity (min/week) A 137 ± 143 78 ± 97 0.008 0.54 B 133 ± 140 82 ± 100 0.022 0.47 Total PA (min/week) A 385 ± 286 268 ± 219 0.016 0.49 B 381 ± 282 274 ± 225 0.032 0.44 Variable . Model . E . NoE . P . d . Off-duty PA at moderate intensity (min/week) A 123 ± 144 147 ± 168 0.390 0.17 B 123 ± 143 149 ± 169 0.340 0.19 Off-duty PA at high intensity (min/week) A 90 ± 113 73 ± 97 0.353 0.19 B 87 ± 111 76 ± 101 0.564 0.12 Off-duty PA total (min/week) A 242 ± 226 263 ± 242 0.626 0.09 B 239 ± 224 270 ± 250 0.484 0.14 Total PA at moderate intensity (min/week) A 216 ± 197 151 ± 146 0.041 0.41 B 214 ± 196 153 ± 149 0.057 0.39 Total PA at high intensity (min/week) A 137 ± 143 78 ± 97 0.008 0.54 B 133 ± 140 82 ± 100 0.022 0.47 Total PA (min/week) A 385 ± 286 268 ± 219 0.016 0.49 B 381 ± 282 274 ± 225 0.032 0.44 E: firefighters who physically train on duty in a fire station; NoE: firefighters who did not physically train on duty in a fire station. Model A: no adjustment; Model B: adjustment for age, length of service, occupational rank, whether they worked at least 1 h in an occupation outside the fire department and whether they worked at least one additional hour at the fire department. Open in new tab Table 2. Comparison between E and NoE regarding PA level Variable . Model . E . NoE . P . d . Off-duty PA at moderate intensity (min/week) A 123 ± 144 147 ± 168 0.390 0.17 B 123 ± 143 149 ± 169 0.340 0.19 Off-duty PA at high intensity (min/week) A 90 ± 113 73 ± 97 0.353 0.19 B 87 ± 111 76 ± 101 0.564 0.12 Off-duty PA total (min/week) A 242 ± 226 263 ± 242 0.626 0.09 B 239 ± 224 270 ± 250 0.484 0.14 Total PA at moderate intensity (min/week) A 216 ± 197 151 ± 146 0.041 0.41 B 214 ± 196 153 ± 149 0.057 0.39 Total PA at high intensity (min/week) A 137 ± 143 78 ± 97 0.008 0.54 B 133 ± 140 82 ± 100 0.022 0.47 Total PA (min/week) A 385 ± 286 268 ± 219 0.016 0.49 B 381 ± 282 274 ± 225 0.032 0.44 Variable . Model . E . NoE . P . d . Off-duty PA at moderate intensity (min/week) A 123 ± 144 147 ± 168 0.390 0.17 B 123 ± 143 149 ± 169 0.340 0.19 Off-duty PA at high intensity (min/week) A 90 ± 113 73 ± 97 0.353 0.19 B 87 ± 111 76 ± 101 0.564 0.12 Off-duty PA total (min/week) A 242 ± 226 263 ± 242 0.626 0.09 B 239 ± 224 270 ± 250 0.484 0.14 Total PA at moderate intensity (min/week) A 216 ± 197 151 ± 146 0.041 0.41 B 214 ± 196 153 ± 149 0.057 0.39 Total PA at high intensity (min/week) A 137 ± 143 78 ± 97 0.008 0.54 B 133 ± 140 82 ± 100 0.022 0.47 Total PA (min/week) A 385 ± 286 268 ± 219 0.016 0.49 B 381 ± 282 274 ± 225 0.032 0.44 E: firefighters who physically train on duty in a fire station; NoE: firefighters who did not physically train on duty in a fire station. Model A: no adjustment; Model B: adjustment for age, length of service, occupational rank, whether they worked at least 1 h in an occupation outside the fire department and whether they worked at least one additional hour at the fire department. Open in new tab Table 3 compares cardiovascular health indicators between E and NoE. Age ranges were, respectively, 24–60 years and 27–57 years for E and NoE firefighters. Length of service was not different (P = 0.130) between both groups (E: 14.9 ± 7.6, NoE: 17.2 ± 7.4 years). A significant difference (P = 0.026) was observed for WC-obesity between E (9%) and NoE (27%). No significant difference was observed for prevalence of BMI-obesity (E: 20%, NoE: 24%, P = 0.710), smoking (E: 3%, NoE: 5%, P = 0.844), dyslipidaemia (E: 9%, NoE: 15%, P = 0.503) and hypertension (E: 8%, NoE: 17%, P = 0.194) between the two groups. Table 3. Comparison between E and NoE regarding cardiovascular health indicators Variables . Model . E . NoE . P . d . Age (years) A 38.8 ± 8.5 41.9 ± 8.6 0.070 0.37 B − − − − HR (bpm) A 64 ± 9 67 ± 9 0.082 0.35 B 64 ± 9 67 ± 10 0.165 0.28 BMI (kg/m2) A 27.0 ± 2.7 28.2 ± 2.9 0.031 0.43 B 27.0 ± 2.6 28.1 ± 2.8 0.061 0.38 WC (cm) A 90.1 ± 7.3 93.8 ± 8.6 0.018 0.48 B 90.4 ± 7.1 93.3 ± 7.9 0.053 0.40 WHtR A 0.51 ± 0.05 0.54 ± 0.05 0.005 0.58 B 0.51 ± 0.05 0.54 ± 0.05 0.017 0.48 TC (mmol/L) A 5.11 ± 0.87 5.25 ± 0.87 0.449 0.15 B 5.15 ± 0.84 5.19 ± 0.88 0.845 0.04 HDL-C (mmol/L) A 1.55 ± 0.39 1.53 ± 0.39 0.796 0.05 B 1.55 ± 0.39 1.52 ± 0.40 0.699 0.08 TC/HDL-C A 3.33 ± 1.07 3.46 ± 1.13 0.561 0.12 B 3.35 ± 1.11 3.43 ± 1.17 0.746 0.07 SBP (mmHg) A 117 ± 11 121 ± 11 0.117 0.32 B 117 ± 11 120 ± 12 0.184 0.27 DBP (mmHg) A 75 ± 8 77 ± 8 0.141 0.25 B 75 ± 8 77 ± 8 0.298 0.21 Variables . Model . E . NoE . P . d . Age (years) A 38.8 ± 8.5 41.9 ± 8.6 0.070 0.37 B − − − − HR (bpm) A 64 ± 9 67 ± 9 0.082 0.35 B 64 ± 9 67 ± 10 0.165 0.28 BMI (kg/m2) A 27.0 ± 2.7 28.2 ± 2.9 0.031 0.43 B 27.0 ± 2.6 28.1 ± 2.8 0.061 0.38 WC (cm) A 90.1 ± 7.3 93.8 ± 8.6 0.018 0.48 B 90.4 ± 7.1 93.3 ± 7.9 0.053 0.40 WHtR A 0.51 ± 0.05 0.54 ± 0.05 0.005 0.58 B 0.51 ± 0.05 0.54 ± 0.05 0.017 0.48 TC (mmol/L) A 5.11 ± 0.87 5.25 ± 0.87 0.449 0.15 B 5.15 ± 0.84 5.19 ± 0.88 0.845 0.04 HDL-C (mmol/L) A 1.55 ± 0.39 1.53 ± 0.39 0.796 0.05 B 1.55 ± 0.39 1.52 ± 0.40 0.699 0.08 TC/HDL-C A 3.33 ± 1.07 3.46 ± 1.13 0.561 0.12 B 3.35 ± 1.11 3.43 ± 1.17 0.746 0.07 SBP (mmHg) A 117 ± 11 121 ± 11 0.117 0.32 B 117 ± 11 120 ± 12 0.184 0.27 DBP (mmHg) A 75 ± 8 77 ± 8 0.141 0.25 B 75 ± 8 77 ± 8 0.298 0.21 E: firefighters who physically train on duty in a fire station; NoE: firefighters who did not physically train on duty in a fire station; HR: 5-min sitting resting heart rate. n = 101 for SBP and DBP (participants on antihypertensive medication were excluded). n = 102 for TC, HDL-C and TC/HDL-C (participants on lipid-lowering medication were excluded). Model A: no adjustment; Model B: adjustment for age, length of service, occupational rank, whether they worked at least 1 h in an occupation outside the fire department and whether they worked at least one additional hour at the fire department. Open in new tab Table 3. Comparison between E and NoE regarding cardiovascular health indicators Variables . Model . E . NoE . P . d . Age (years) A 38.8 ± 8.5 41.9 ± 8.6 0.070 0.37 B − − − − HR (bpm) A 64 ± 9 67 ± 9 0.082 0.35 B 64 ± 9 67 ± 10 0.165 0.28 BMI (kg/m2) A 27.0 ± 2.7 28.2 ± 2.9 0.031 0.43 B 27.0 ± 2.6 28.1 ± 2.8 0.061 0.38 WC (cm) A 90.1 ± 7.3 93.8 ± 8.6 0.018 0.48 B 90.4 ± 7.1 93.3 ± 7.9 0.053 0.40 WHtR A 0.51 ± 0.05 0.54 ± 0.05 0.005 0.58 B 0.51 ± 0.05 0.54 ± 0.05 0.017 0.48 TC (mmol/L) A 5.11 ± 0.87 5.25 ± 0.87 0.449 0.15 B 5.15 ± 0.84 5.19 ± 0.88 0.845 0.04 HDL-C (mmol/L) A 1.55 ± 0.39 1.53 ± 0.39 0.796 0.05 B 1.55 ± 0.39 1.52 ± 0.40 0.699 0.08 TC/HDL-C A 3.33 ± 1.07 3.46 ± 1.13 0.561 0.12 B 3.35 ± 1.11 3.43 ± 1.17 0.746 0.07 SBP (mmHg) A 117 ± 11 121 ± 11 0.117 0.32 B 117 ± 11 120 ± 12 0.184 0.27 DBP (mmHg) A 75 ± 8 77 ± 8 0.141 0.25 B 75 ± 8 77 ± 8 0.298 0.21 Variables . Model . E . NoE . P . d . Age (years) A 38.8 ± 8.5 41.9 ± 8.6 0.070 0.37 B − − − − HR (bpm) A 64 ± 9 67 ± 9 0.082 0.35 B 64 ± 9 67 ± 10 0.165 0.28 BMI (kg/m2) A 27.0 ± 2.7 28.2 ± 2.9 0.031 0.43 B 27.0 ± 2.6 28.1 ± 2.8 0.061 0.38 WC (cm) A 90.1 ± 7.3 93.8 ± 8.6 0.018 0.48 B 90.4 ± 7.1 93.3 ± 7.9 0.053 0.40 WHtR A 0.51 ± 0.05 0.54 ± 0.05 0.005 0.58 B 0.51 ± 0.05 0.54 ± 0.05 0.017 0.48 TC (mmol/L) A 5.11 ± 0.87 5.25 ± 0.87 0.449 0.15 B 5.15 ± 0.84 5.19 ± 0.88 0.845 0.04 HDL-C (mmol/L) A 1.55 ± 0.39 1.53 ± 0.39 0.796 0.05 B 1.55 ± 0.39 1.52 ± 0.40 0.699 0.08 TC/HDL-C A 3.33 ± 1.07 3.46 ± 1.13 0.561 0.12 B 3.35 ± 1.11 3.43 ± 1.17 0.746 0.07 SBP (mmHg) A 117 ± 11 121 ± 11 0.117 0.32 B 117 ± 11 120 ± 12 0.184 0.27 DBP (mmHg) A 75 ± 8 77 ± 8 0.141 0.25 B 75 ± 8 77 ± 8 0.298 0.21 E: firefighters who physically train on duty in a fire station; NoE: firefighters who did not physically train on duty in a fire station; HR: 5-min sitting resting heart rate. n = 101 for SBP and DBP (participants on antihypertensive medication were excluded). n = 102 for TC, HDL-C and TC/HDL-C (participants on lipid-lowering medication were excluded). Model A: no adjustment; Model B: adjustment for age, length of service, occupational rank, whether they worked at least 1 h in an occupation outside the fire department and whether they worked at least one additional hour at the fire department. Open in new tab Red/processed meat (E: 5.6 ± 3.4, NoE: 5.5 ± 3.5 servings/week, P = 0.942, d = 0.03), sweet drinks (E: 1.7 ± 3.6, NoE: 1.3 ± 2.9 servings/week, P = 0.395, d = 0.12) and alcohol (E: 5.5 ± 4.9, NoE: 5.0 ± 4.6 servings/week, P = 0.592, d = 0.10) consumption were not different between the two groups. However, vegetables/fruit consumption was significantly (P = 0.002, d = 0.56) different between E (4.6 ± 2.7 servings/day) and NoE (3.2 ± 2.1 servings/day) firefighters. Psychological stress was not different between the two groups (E: 29.0 ± 6.8, NoE: 29.7 ± 6.7, P = 0.612, d = 0.10). After adjustment for age, smoking, psychological stress and vegetables/fruit, sweet drinks, red/processed meat and alcohol consumption, the total PA level was correlated with BMI (r = −0.223, P = 0.033), WC (r = −0.211, P = 0.044), waist-to-height ratio (WHtR) (r = −0.235, P = 0.020), DBP (r = −0.283, P = 0.006), HRrest (r = −0.295, P = 0.004) and HDL-C (r = 0.245, P = 0.018). Discussion Firefighters who physically train on duty were more physically active on a weekly basis, had a lower WC-obesity and physical inactivity prevalence and showed a lower WHtR than firefighters who do not physically train on duty. This cross-sectional study points to an association between on-duty PA and the cardiovascular health of firefighters. To our knowledge, this study is the first to compare the PA and cardiovascular health of firefighters who physically train on duty to those who do not. Another strength of this study is that the participants’ physical characteristics are fairly representative of full-time firefighters in Québec, as reported in Gendron et al. [2]: mean BMI after adjustment for age (27.6 ± 3.2 versus 27.6 ± 3.2 kg/m2, P = 0.830) and BMI-obesity prevalence (22% versus 23%, P = 0.897), none being significantly different. Nevertheless, the study has some limitations. First, its cross-sectional design restricts our ability to make causal interpretations about the relationships between on-duty exercise and cardiovascular health outcomes. Also, the differences between E and NoE groups were not statistically significant for WC and BMI, possibly because of a lack of statistical power due to a small sample size. The post hoc estimated statistical power for these variables was 0.49 and 0.47, respectively: it is likely that more participants would have increased significance. Based on the power values, twice the number of participants (~220) would have rendered a power of ~0.80. Moreover, HR and BP measures may be inaccurate since participants were tested at different times of the day, some even as they just returned from an intervention. The unpredictability of calls made it difficult for participants to follow specific preliminary instructions. As mentioned previously, a similar study reported that firefighters in departments having a diversified health promotion programme were healthier [10]. The reality is that most Québec fire departments do not have any official diversified health promotion programme but allow firefighters to physically train during working hours. It was therefore relevant to study for the first time the on-duty physical training and its potential effects on the total PA level and cardiovascular health. Our small sample size decreases however statistical power for important variables such as WC and BMI which is not the case in Poston et al. [10]. This last study is nevertheless limited because of its cross-sectional design just like ours. An important result in our study is that more E firefighters than NoE firefighters had access to a gym at work: equipment availability would seem to encourage firefighters to practice PA while on duty. Allowing time for on-duty exercise and supplying equipment/facilities are indeed part of the WFI and researchers’ recommendations [21]. Doing on-duty PA allowed firefighters to cumulate a higher total PA level on a weekly basis. This echoes Poston et al. [10] who reported that, in departments with WFI, a higher proportion of firefighters practice PA regularly at work and have a higher PA level than firefighters in standard departments. A higher PA level may have a beneficial effect on body composition and explain in part the significantly lower prevalence of WC-obesity in E firefighters, as well as their significantly lower WHtR and their tendency to have lower BMI and WC. This is also supported by correlations of total PA level with WHtR, WC and BMI. However, the non-significant difference of BMI-obesity prevalence in our study might lead us to believe that the risk of cardiac event would be similar in both groups. In firefighters, after statistical adjustments for other CVD risk factors, only BMI-obesity was associated with fatal on-duty coronary heart disease events [22]. A high BMI was also associated with a high left ventricular mass in firefighters [23], a quite common substrate of cardiac event among those workers [24]. There are no studies verifying the relation between WC-obesity and fatal on-duty cardiac events in firefighters. It is likely that the risk of an on-duty cardiac event may be lower among E firefighters as WC, the best anthropometric measure for estimating abdominal visceral adipose tissue accumulation [25], is an excellent independent predictor of myocardial infarction [26]. These researchers [26] also reported that WC is a better predictor of myocardial infarction than BMI. They demonstrated that, when adjusted for WC, BMI is no longer a predictor of myocardial infarction. WHtR is also an important predictor of CVD and its risk factors according to Ashwell et al. [27]. All these previous results pertaining to body composition suggest that E firefighters would be less likely to have a CVD and suffer from on-duty cardiac event. Excess body fat may also impact firefighters’ performance in many ways. When protective clothing is worn, body fat acts as an insulator and obstructs heat dissipation during exposure to hot environmental conditions, thus contributing to a greater rise in core temperature [28]. Body fat also acts as a dead weight during the performance of tasks that require lifting one’s own BW, like when climbing ladders and stairs [29], leading to an increased metabolic rate and correlative increase in heat storage. A greater metabolic rate and a rise in core temperature result in high cardiac/cardiovascular strain and consequently increase the risk of SCD. The non-significant differences between the groups in WC, BMI, HRrest, DBP and HDL-C suggest that, while on-duty PA allows firefighters to practice more PA on a weekly basis, it is not enough to significantly impact those variables. A greater difference in PA level might generate significant differences between the groups in WC, BMI, HRrest, DBP and HDL-C since we reported a significant correlation between PA level and those variables after adjustments for covariates that may also bear on the CVD risk [30]. Ultimately, controlled experimental studies are needed to assess the effectiveness of on-duty physical training, and our findings support the need for such endeavour to confirm its benefits. Acknowledgements The authors thank all municipal fire departments and unions that encouraged their employees/members to participate in the study. Finally, the authors are grateful to all the firefighters who participated in this study. Funding P.G. was supported by a doctoral research scholarship from the Fonds de Recherche du Québec - Santé (FRQS). Competing interests All authors declare that they have no conflict of interest. References 1. Smith DL , DeBlois JP, Kales SN, Horn GP. 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TI - Physical training in the fire station and firefighters’ cardiovascular health
JO - Occupational Medicine
DO - 10.1093/occmed/kqaa060
DA - 2020-06-20
UR - https://www.deepdyve.com/lp/oxford-university-press/physical-training-in-the-fire-station-and-firefighters-cardiovascular-xiuYENRv10
SP - 224
EP - 230
VL - 70
IS - 4
DP - DeepDyve
ER -