Cardiovascular Disease Risk Factors, Musculoskeletal Health, Physical Fitness, and Occupational Performance in Firefighters: A Narrative Review

Table 4

Relationship between CVD risk factors musculoskeletal health, physical fitness, and occupational performance (n = 46).

References	Year	Sample and setting	Study design (sampling)	Outcome
Cardiovascular disease risk factors and musculoskeletal health (n = 7)
Poston et al. [41]	2011	478 full-time male firefighters	Cross-sectional	(i) Age, BMI, smoking status, and general health were significant predictors of work injury ().
		USA		(ii) Firefighters categorised with class II and III obesity were significantly more likely to sustain injuries (OR: 4.89).
Jahnke et al. [22]	2013	347 full-time firefighters	Prospective cohort	(i) Obese firefighters were 5.2 times more likely to experience musculoskeletal injury.
		Kansas, Missouri, Iowa, Nebraska, North Dakota, South Dakota, Colorado, and Wyoming, US		(ii) Firefighters with central obesity were 2.8 times more likely to experience musculoskeletal injury.
Jahnke et al. [21]	2013	462 full-time firefighters	Cross-sectional	(i) Cigarette smokers were more likely to sustain injuries compared to nonsmokers.
		Kansas, Missouri, Iowa, Nebraska, North Dakota, South Dakota, Colorado, and Wyoming, US
Gordon and Lariviere [42]	2014	252 full-time male and female firefighters	Cross-sectional	(i) Age (OR: 6.49) and years of experience (OR: 0.1) were significant predictors of injury.
		Ontario, Canada
Jang et al. [43]	2016	392 full-time firefighters	Cross-sectional	(i) Age was a significant predictor of lumbar intervertebral disc degeneration (), regardless of core job description.
		Dongguk, Goyang, Korea
Damrongsak et al. [44]	2017	298 male firefighters conveniently sampled	Cross-sectional	(i) Age (), BMI (χ^2 = 127.84, df = 4, ), current back pain, occupational stress, history of back pain were significant predictors of current back pain.
		Southeastern United States, USA
Negm et al. [45]	2017	294 full-time firefighters	Cross-sectional	(i) Older (≥42 years) firefighters had significantly more severe lower-extremity disability and more severe back pain
		Hamilton, Trenholme, Canada		(ii) Older firefighters were significantly more likely to have multiple musculoskeletal disorders.
Cardiovascular disease risk factors and physical fitness (n = 17)
Donovan et al. [46]	2009	214 male firefighters	Cross-sectional	(i) Cardiorespiratory fitness was inversely related to metabolic abnormalities ().
		Colorado, USA
Baur et al. [47]	2011	968 male firefighters,	Cross-sectional	(i) Metabolic equivalents (METs) were inversely related to diastolic blood pressure (DBP), body fat, triglycerides, low-density lipoprotein cholesterol (LDL-C) and total/high-density cholesterol (TC/HDL-C) ratio, and high-density lipoprotein cholesterol (HDL-C).
		USA
Punakallio et al. [24]	2012	70 male firefighters aged 30 to 44 years	Longitudinal	(i) Increased weekly exercise reduced the decline in cardiorespiratory fitness.
		Finland		(ii) Regular smoking and more than 15 units of alcohol a week were significant predictors of a decline in cardiorespiratory fitness.
Baur et al. [48]	2012	1149 male firefighters, USA	Cross-sectional	(i) Cardiorespiratory fitness was inversely associated with ECG and autonomic exercise testing abnormalities before and after adjustment for age, BMI and metabolic syndrome.
Mayer et al. [49]	2012	83 full-time firefighters	Cross-sectional	(i) Back and core muscular endurance was 27% lower in obese firefighters. Back and core muscle endurance were related to obesity.
		Tampa, Florida, USA		(ii) Significant negative correlations were reported between back endurance and age (), BMI (), and BF% (), and between core endurance and BMI (), BF% (), and fat free mass ().
Poplin et al. [50]	2013	577–799 full-time firefighters	Longitudinal	(i) Age was a significant modifier of V̇O2max ().
		Southwestern States, USA
Kiss et al. [51]	2014	1225 firefighters	Cross-sectional	(i) Cardiorespiratory fitness was significantly related to age-group, body mass index (BMI) groups, and body fat percentage.
		East-Flanders Province, Belgium
Walker et al. [52]	2014	73 full-time male firefighters, Australia	Cross-sectional	(i) Aging was significantly related to poor cardiorespiratory fitness ().
				(ii) Aging was related to a significant decrease in cardiorespiratory fitness between the 35–44 and 45–54-year age groups ().
Poplin et al. [53]	2015	799 full-time firefighters	Retrospective occupational cohort	(i) Age was negatively correlated with V̇O2max (r = −0.368, ), flexibility (r = −0.160, ).
		Southwestern states, USA		(ii) BF% was negatively correlated with V̇O2max (r = −0.448, ), grip strength (r = −0.191, ), and flexibility (r = −0.135, ).
Seyedmehdi et al. [29]	2016	157 full-time male firefighters, Tehran	Cross-sectional	(i) Cardiorespiratory fitness (V̇O2max) was significantly correlated with age, BMI, cigarette smoking, physical activity, LDL-C, HDL-C, SBP, DBP, and heart rate ().
Kirlin et al. [54]	2017	97 female firefighters, San Diego, USA	Cross-sectional	(i) Relative V̇O2, absolute V̇O2 and maximum METs were significantly associated with age.
Li et al. [55]	2018	294 full-time firefighters, Colorado, USA	Cross-sectional	(i) BF% (), estimated V̇O2max (), metabolic syndrome (), and age group () were significantly related to 10-year atherosclerotic cardiovascular disease risk.
Barry et al. [56]	2019	29 male full-time firefighters conveniently sampled, USA	Cross-sectional	(i) Waist circumference (WC) was a significant predictor of V̇O2max.
				(ii) More physically active firefighters had a higher V̇O2max.
Espimoza et al. [57]	2019	76 volunteer male firefighters, Chile	Cross-sectional	(i) Age, BMI, WC, waist-to-hip ratio (WHR), BF% and fat mass was significantly correlated with V̇O2max.
				(ii) Resting heart rate (RHR), SBP, DBP, and blood glucose were significantly correlated with V̇O2max.
Porto et al. [58]	2019	64 full-time firefighters (38 on-duty and 26 off-duty), federal District (Brasilia), Brazil	Cross-sectional	(i) Cardiorespiratory fitness (V̇O2max) was positively correlated with overall cardiac autonomic function and higher parasympathetic activity ().
Yang et al. [59]	2019	1562 full-time firefighters participated at baseline and 1104 of these firefighters participated at follow-up, Indiana, USA	Retrospective longitudinal cohort	(i) Age, BMI, SBP, DBP, total cholesterol (TC), LDL-C, triglycerides, glucose concentration, and smoking status were significantly different between push-up categories (upper body endurance).
Strauss et al. [8]	2021	97 full-time firefighters <60 years. Westphalia, Germany	Cross-sectional	(i) BMI, WC, BF%, and resting SBP, triglycerides, and total cholesterol values were significantly lower with increased cardiorespiratory fitness (V̇O2max) (, age-adjusted).
Cardiovascular disease risk factors and occupational performance (n = 6)
Airila et al. [60]	2012	403 male firefighters, Kuopio, Finland.	Longitudinal	(i) Age (r = −0.33, ) and BMI (r = −0.15, ) were negatively related to work ability, and cigarette smoking was negatively related to work demands (r = −0.10 ), and physical exercise was positively related to work ability index (r = 0.015, ) and work demands (r = 0.018, ).
Walker et al. [52]	2014	73 full-time male firefighters, Australia	Cross-sectional	(i) Aging was significantly related to worse performance of simulated operational power testing tasks ().
				(ii) Hose-drag times significantly increased between 25–34 and 45–54 () and 35–44 and 45–54 year age-groups (). Dummy-drag times significantly increased between 25–34 and 45–54 (), and 35–44 and 45–54-year age-groups ().
Firoozeh et al. [61]	2017	375 full time male firefighters, Tehran	Cross-sectional	(i) Age (r = -0.277, ), BMI (r = −0.187, ) and work experience (r = −0.281, ) were negatively correlated with work ability.
				(ii) Leisure time physical activity (r = 0.206, ) was related to work ability.
Phillips et al. [7]	2017	414 male firefighters, Alberta, Canada	Longitudinal	(i) The obese firefighting group had a significantly shorter treadmill time, lower relative V̇O2max and absolute V̇O2max.
				(ii) The heaviest groups had significantly lower completion times for the hose drag, weighted sled pull, forcible entry, and victim rescue.
				(iii) The lightest firefighters had a significantly lower time for the ladder climb.
Nazari et al. [26]	2018	46 male and 3 female firefighters between the ages of 20–69 years, Canada	Secondary analysis	(i) Age and grip strength were significant predictors of hose drag and stair climb completion times ().
Saari et al. [62]	2020	74 full-time male firefighters were conveniently sampled, Kentucky, USA	Cross-sectional	(i) Older firefighters (≥37 years) had an 8.8% increase in completion time for the firefighting course.
				(ii) Age was positively correlated with course time (r = 0.297, ).
Xu et al. [63]	2020	20 full-time male firefighters, Southeast China	Cross-sectional	(i) High BF% was associated with poor performance in ability tests.
Norris et al. [64]	2021	19 full-time male firefighters, Texas, USA	Cross-sectional	(i) Age and fat mass were significant predictors of work efficiency.
Musculoskeletal health and physical fitness (n = 5)
Wynn and Hawdon [65]	2012	Firefighter recruits with minimum cardiorespiratory fitness standard (398 full-time and 48 part-time recruits) and without fitness standard (198 full-time and 206 part-time subjects). Northern England	Cohort	(i) Injury-related restrictions were more likely where no cardiorespiratory fitness standard was applied.
				(ii) Firefighters with a higher V̇O2max correlated with a lower incidence of injuries ()
Butler et al. [66]	2013	108 trainee firefighters, Orange County, USA	Cohort	(i) Three functional movement screening (FMS) movements were significant predictors of injury i.e., the sit-and-reach (OR: 1.24), the deep-squat (OR: 1.21), and the push-up (OR: 1.30).
Jahnke et al. [21]	2013	462 full-time firefighters, Kansas, Missouri, Iowa, Nebraska, North Dakota, South Dakota, Colorado, and Wyoming, USA	Cross-sectional	(i) Injuries were 4.6 times more likely to be sustained when firefighters regularly exercised, while on duty. Increased V̇O2max (OR: 1.06) and strength (OR: 4.03) were significantly associated with injury while exercising or training.
Poplin et al. [50]	2013	577–799 full-time firefighters, Southwestern States, USA	Longitudinal	(i) Firefighters in the lowest fitness category (V̇O2max < 43 mL·kg^−1·min^−1) were 2.2 times more likely to sustain injury than firefighters in the highest fitness level category (V̇O2max > 48 mL·kg^−1·min^−1).
				(ii) A V̇O2max between 43 and 48 mL·kg^−1·min^−1 were 1.38 times more likely to incur injury.
				(iii) Improving relative aerobic capacity by one metabolic equivalent reduced the risk of injury by 14%.
Poplin et al. [53]	2015	799 full-time firefighters, Southwestern States, USA	Retrospective occupational cohort	(i) Firefighters with lower cardiorespiratory fitness were at increased risk of injury.
				(ii) The risk of injury was 1.82 times more likely for the least fit firefighters.
				(iii) When restricted to sprains and strains, the risk of injury increased to 2.90.
Musculoskeletal health and occupational performance (n = 5)
Punakallio et al. [67]	2014	411 full-time male firefighters, Helsinki, Finland	Longitudinal	(i) Musculoskeletal pain (MSP) in more than one site diminished work ability.
				(ii) Low back pain (OR = 1.9) forearm and hands pain (OR = 1.9) predicted diminished work ability
				(iii) Participants who were on disability pension were older, more often had poor work ability, and had slightly more MSP at baseline.
				(iv) Average-(OR: 3.1)-to-high (5.3) physical workload was a significant risk factor for retiring on disability pension.
Kodom-Weredu [68]	2018	320 full-time firefighters	Cross-sectional	(i) Work-related musculoskeletal disorders (WMSD) were significantly related to work demands (r = 0.023) and task characteristics (r = 0.026). Work demands (β = 0.226, ) and task characteristics (β = 0.214, ) were significant predictors of WRMSDs.
		The greater Accra region of Ghana
MacDermid et al. [40]	2019	293 full-time male and female firefighters	Cross-sectional	(i) Firefighters who reported moderate-severe muscle and joint problems took 10 seconds longer to perform the stair climb, but were not statistically significant.
		Hamilton, Ontario, Canada
Saremi et al. [69]	2019	250 full-time firefighters	Cross-sectional	(i) Work ability index had negative correlation with discomfort in the wrists (r = –0.170, ), legs (r = –0.129, ), and ankles (r = –0.176, .
		Tehran (North, South, East, and West)
Nazari et al. [39]	2020	325 full-time firefighters	Cross-sectional survey	(i) Firefighters with spinal pain experienced significantly more output limitation. Firefighters above 45 years experienced more physical work limitations. The number of musculoskeletal pain sites, age, and years of service predicted occupational output and work limitations.
		Hamilton, Ontario, Canada
Physical fitness and occupational performance (n = 11)
von Heimburg et al. [70]	2006	13 full-time male firefighters aged between 24 and 56 years.	Cross-sectional	(i) V̇O2max was a significant predictor of simulation performance time. Better work performance was related to firefighters who were stronger, heavier, and taller.
		Nord-Trøndelag County, Norway
Elsner and Kolkhorst [84]	2008	20 full-time male firefighters	Cross-sectional	(i) There was a moderately strong inverse relationship between the average V̇O2max during the firefighting simulation protocol and performance time.
		San Diego, USA
Sheaff et al. [72]	2010	33 full time firefighters, male (26) and female (7) aged between 18 and 45 years	Cross-sectional	(i) V̇O2max, upper body strength, grip strength, and the HR response to stair climbing were significantly related to better performance on the candidate physical ability test (). Absolute V̇O2max predicted candidate physical ability test performance ().
		Baltimore, Washington, USA
Michaelides et al. [73]	2011	90 full-time firefighters	Cross-sectional	(i) Ability test (AT) completion time was associated with abdominal strength (), relative power (), upper-body muscular endurance and upper-body strength (). Poor performance on the AT was associated with high resting heart rate (), high BMI (), high BF% (), aging (), and high WC ().
		Arkansas, USA
Heimburg et al. [74]	2013	63 full-time firefighters.	Cross-sectional	(i) Firefighters with higher a V̇O2max who were stronger completed the simulation protocol faster (). Some firefighters with below average strength were among the quickest, indicating that a minimal strength was needed to perform well, and strength beyond that point did not improve performance times.
		Trondheim, Norway.
Kleinberg et al. [75]	2016	46 full-time male firefighters aged 24 to 50 years	Cross-sectional	(i) Quadriceps muscle strength was significantly associated with stair climb time (r = 20.492, ), and remained significant after adjustment for age and BMI.
		North Carolina, USA
Siddal et al. [76]	2018	68 (63 male; 5 female) full-time firefighters	Cross-sectional	(i) Age, sex, height and/or lean mass were not significant predictors of the firefighter simulation test (FFST) performance time. The strongest predictor of FFST time was absolute V̇O2 and fat mass.
		Bath, England, United Kingdom
Nazari et al. [26]	2018	46 male and 3 female firefighters between the ages of 20–69 years.	Secondary analysis	(i) Grip strength and lower body strength were significant predictors of hose drag and stair climb completion times (), respectively.
		Canada
Skinner et al. [77]	2020	42 male aviation rescue firefighters (ARFF)	Cross-sectional	(i) V̇O2max (), anaerobic step test (), height () and lean mass () were inversely correlated with ARFF emergency protocol simulation performance time. Slower performance time was associated with higher fat mass () and BF% (). Muscular strength, muscular endurance and flexibility were not related to performance on the simulated ARFF emergency protocol.
		Queensland, Australia
Xu et al. [63]	2020	20 full-time male firefighters	Cross-sectional	(i) High BF% was associated with poor performance in ability tests, V̇O2max was associated with increased performance, and upper and lower body muscular power were both inversely related to firefighter ability test completion time.
		Southeast China
Norris et al. [64]	2021	19 full-time male firefighters	Cross-sectional	(i) Experience, jump height, inverted row endurance, relative bench and squat strength, and relative V̇O2 were significant predictors of work efficiency ().
		Texas, USA

Note. Studies that were included were categorised chronologically. Few studies compared variables in more than one relationship and, therefore, few studies are repeated in the table.