Effects of fitness on self-reported physical and mental quality of life in professional firefighters: An exploratory study

Abstract

BACKGROUND:

The work-related stress experienced by firefighters is associated with numerous health issues. In the general population, improving physical fitness is associated with improvements in both mental and physical quality of life.

OBJECTIVE:

The purpose of the study was to examine whether fitter professional firefighters report greater physical and mental quality of life.

METHODS:

Twenty-three professional firefighters (males = 21, females = 2; age: 36.78±7.12yrs; height: 176.96±5.67 cm; weight: 88.20±16.02 kg; years of service: 8.70±6.62years) volunteered for the study. Participants completed a fitness protocol that included the wall sit and reach, Y-balance test, vertical jump, 1 repetition maximum bench press, pull-ups to failure, push-ups to failure, a plank hold and 1-mile run. The short form 36 questionnaire was used to assess overall quality of life. Firefighters were divided into “high” and “low” groups for physical and mental quality of life. Group differences in fitness parameters were assessed using a multivariate analysis of covariance with gender, age, years of service, height, and body mass as co-variates.

RESULTS:

Firefighters with lower mental quality of life had lower body fat percentages (p = 0.003), fat mass (p = 0.036), greater fat free mass (p = 0.015), vertical jump height (p = 0.024) and performed more pull-ups (p = 0.003). There were no significant differences in any of the fitness measures between high and low physical quality of life groups.

CONCLUSION:

The findings indicate that physical fitness of firefighters is not indicative of overall health. Firefighters might use exercise to cope for psychological stress and a holistic approach to improve firefighter quality of life is recommended.

Keywords

Body composition mental health physical health wellbeing emergency responders

1 Introduction

Firefighting is a physically and mentally demanding profession. The physical occupational demands of firefighting require high level of fitness to complete common tasks (i.e. carrying equipment, pushing and pulling loads, climbing ladders or stairs). As a result of the physical demands firefighters frequently experience musculoskeletal injury. For example, in 2020 an estimated 64,875 firefighters were injured in the line of duty with 31% of the injuries occurred while responding to an emergency call [1].

In addition to physiological stress firefighters encounter extensive psychological stress due to exposure to traumatic events [2]. Firefighter’s repeated exposure to traumatic events increases the risk of development of post-traumatic stress disorder (PTSD) and as a result PTSD is highly prevalent in firefighters [3]. The shift schedules commonly employed by fire departments create a barrier for many firefighters to live healthy lifestyles which could help to reduce the symptoms of PTSD. Shift work has been directly associated with the distruption of the circadian rhythm [4]. Prolonged alterations of circadian rhythm have been linked to serious physical health issues such as metabolic disorders, cardiovascular disease, and cancer [5]. Additonally, shift work has been reported to have negative effects on psychosocial factors such as interpersonal relationships, marital issues, increased feelings of loneliness among spouses, and feelings of anger due to firefighters’ absence because of shift work [6].

The combination of physical and mental stress results in the overall work-related stress (WRS) experienced by firefighters. Stressors such as individual wellness, occupational purpose, sense of belonging, and needs are associated with WRS and has been defined as occupational emotional fitness [7]. Firefighter WRS and occupational emotional fitness can be detrimental to their overall quality of life [8]. Health related quality of life (HRQoL) has been defined as an individual’s quality of life analogous to their health or disease status [9]. HRQoL is a multidimensional framework which commonly includes aspects of physical, psychological, social, and environmental factors [9]. The use of The 36-Item Short Form Health Survey (SF-36) is commonly used in literature and is comprised of eight scales; physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, and mental health [10]. These components of the SF-36 are further broken down into two constructs for physical and mental determinants of health [10]. Physical fitness has been reported to be protective of overall health with higher levels being associated with greater physical [11] and mental health [12] among the general population (i.e., non-physical labors). HRQoL has been reported to have a significant negative association with individuals who are underweight and a stronger negative association with those who are obese [13]. Additionally, muscular strength and cardiorespiratory fitness have been positively associated with HRQoL.

Whether these same benefits of fitness on HRQoL observed in the general population are applicable to firefighters who are exposed to intense levels of WRS remains to be determined. Vidotti et al. investigated HRQoL among 30 male firefighters and reported that HRQoL was significantly associated with work ability [14]. The authors suggested that greater HRQoL may lead to enhanced work ability and HRQoL should be associated with physical fitness. Our purpose was to explore the effects of physical fitness on physical and mental health among fit and unfit professional firefighters within the same department. We hypothesize that firefighters with greater levels of physical fitness will self-report higher levels of physical and mental components of HRQoL.

2 Methods

2.1 Participants

Twenty-three professional career firefighters (males = 21, females = 2; age: 36.78±7.12 yrs; height: 176.96±5.67 cm; weight: 88.20±16.02 kg; years of service: 8.70±6.62 yrs) volunteered for the study. Participants were recruited from a large county fire department, following the approval of the county’s public safety department participants were solicited for inclusion via flyers and email. To be eligible for the intervention participants were required to: 1) not have surgery or injury in the last 3 months; 2) ability to run, perform pull-ups and push-ups without pain; 3) no history of cardiovascular, pulmonary, renal, or metabolic disease and 4) engage on average 30 minutes of physical activity daily. All participants signed the informed consent prior to participation in the study. The study was approved by George Mason University’s Institutional Review Board (IRB #: 1389424-1).

2.2 Protocol

Testing was completed during a single 90-minute session, indoors in a climate controlled fitness center and each firefighter was tested individually. Upon arrival to the research lab participants signed the informed consent. Participants were requested to avoid strenuous exercise for 48 hours before testing and advised not to consume food or fluid, other than water, for 2 hours prior to testing. Participants completed a quality of life survey, then anthropometric and body composition were measured followed by a battery of fitness assessments. The order of the fitness assessments was wall sit and reach (WSR), Y-balance test (YBT), vertical jump (VJ), 1-repetition maximum bench press (1RMBP), pull-ups to volitional fatigue (PULL), push-ups to volitional fatigue (PUSH), a plank hold and 1-mile run. To minimize the influence of fatigue each participant was given 5 minutes of recovery between fitness assessments. Participants performed a dynamic warm up following the YBT in accordance with the Functional Movement Screen^TM using a standard and supervised procedure to minimize injury during fitness assessments [15]. Rest periods were determined from pilot testing of the protocol. All test sessions were supervised by Certified Strength and Conditioning Specialists (CSCS).

2.3 Study measures

HRQoL Survey: The 36-Item Short Form Survey (SF-36) was used to assess overall quality of life. The survey instrument consists of 8 subscales of health (physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, and mental health), four of the components are the core domains of quality of life (physical health, mental health, social health, and functional health). Each item is scored 0 to 100 and a higher the total score is associated with a more favorable health state. A physical and mental health component score is then computed based on algorithms provided by the developer. The SF-36 has been found to be a valid and reliable instrument when administered to a variety of populations [16].

Anthropometrics: Height and mass were recorded to the nearest 0.01 cm and 0.02 kg, respectively. Height was recorded with a stadiometer (Detecto, Webb, MO, USA) and mass with a digital scale (BOD POD; Cosmed USA, Concord, CA, USA). Percent body fat, fat mass, and fat-free mass were estimated using air displacement plethysmography (BOD POD model 2000A; BOD POD, Cosmed USA, Concord, CA, USA) following standardized procedures by the manufacturer. Air displacement plethysmography is a reliable and valid method of assessing body composition [17].

Fitness Assessment: Lower body flexibility was assessed with the wall sit and reach test. Participants sat without shoes and the soles of their feet flat against the sit and reach box. Once seated participants slowly reached forward with parallel arms and fingertips overlapped holding the final position for two seconds. The score was measured at the most distal point of the fingertips with the best score of two trials used as the final score. The WSR has been previously reported to be a valid (r = 0.77) and reliable (ICC = 0.95) test to determine lower body flexibility, [18].

To measure lower extremity balance and motor control the Y-balance test-lower quarter was performed on the Y-balance test (YBT) device (Functional Systems, Chatham, Virginia). Testing followed the specific guidelines established by Cook et al. [19]. The protocol was repeated until the participants completed 3 attempts per leg [20]. The greatest reach distance from all trials in each direction per leg was used for further analysis. Reach distances were normalized by dividing by limb length. Composite scores for each limb were computed as the sum of the normalized score in each direction divided by 3.

The countermovement VJ was used to assess lower body power. Subjects performed the vertical jump assessment directly after the dynamic warm-up. Instructions were to use a countermovement technique with an arm swing and to jump “as high as possible” on each attempt. A minimum of 3 attempts were given and continued until performance plateaued or decreased. The vertical jump was performed on a timing mat (Just Jump, Perform Better, Cranston, RI, USA), which has been reported to be both valid and reliable for assessing countermovement jump performance [21].

A 1RMBP, maximum effort pull-ups to volitional fatigue and maximum effort push-ups to volitional fatigue were used to assess upper body muscular fitness. The procedures used to obtain these measures have been previously described [22]. Furthermore, the upper body fitness assessments have been found to be both valid and reliable. The 1RMBP is considered to be a reliable upper body strength assessment [23]. The maximum repetition pull-up assessment has been reported to be a reliable assessment (ICC = 0.96) of upper body pulling strength [24]. The use of maximal repetition push-up to measure anterior muscular endurance has been reported to be a valid and reliable assessment [25].

Core muscular function and endurance was assessed with a maximal forearm plank hold. A demonstration of the correct posture was provided prior to the start of the test. Instructions were to “keep a straight line between your shoulders, hips, knees and ankles” and “hold the position as long as possible”. Once subjects were in the correct position the test began exactly 5 minutes following the push-up assessment. During testing subjects were provided 1 warning if they began to deviate from the correct posture. Time was recorded on a stopwatch to the nearest second. The isometric prone plank hold has been reported to be a valid and reliable assessment of core muscle function [26].

Aerobic endurance was assessed with a timed 1 mile run on an indoor track. Participants were instructed to complete the 1 mile run as fast as possible. During the test researchers provided consistent encouragement to all participants. The time to complete 1 mile was recorded to the nearest second. The 1-mile run assessment has been previously reported to be a valid field test of VO2 max [27].

2.4 Statistical analysis

Descriptive statistics were calculated for all health and physical fitness variables and reported as means and 95% confidence interval. Normality was assessed with Shapiro-Wilks tests and visual inspection of histograms. A majority of the variables were normally distributed, except mass, fat-mass, and 1 mile time. The non-normal variables were all positively skewed. Using a log base 10 transformation body mass, fat-mass and 1 mile time the data were transformed to be normally distributed. Participants were divided into “high” and “low” groups for physical and mental health based on median values. Group differences in fitness parameters were assessed using a multivariate analysis of covariance (MANCOVA) with gender, age, years of service, height, and body mass as co-variates. MANCOVA assumptions were checked (multicollinearity, normality, homogeneity of variance) and partial eta-squared η_p² was used to assess effect size. Effect sizes were interpreted as small (η_p² = 0.01), medium (η_p² = 0.06), and large (η_p² = 0.14). All statistical analyses were performed using R (version 4.0.3, R Core Team, Vienna, Austria), alpha was set at < 0.05.

3 Results

Descriptive data, fitness parameters, and quality of life means are presented in Tables 1 and 2. The mental and physical health composite scores were 55.0±4.3 and 46.5±7.5, respectively. The MANCOVA indicated that firefighters who self-reported lower mental health scores had significantly lower body fat percentage (F_1,16 = 11.743, p = 0.003, η_p² = 0.423, β=0.895) and fat mass (F_1,64 = 5.238, p = 0.036, η² = 0.247, β=0.575; Table 2). Additionally, the low mental health group had significantly greater fat free mass (F_1,16 = 7.366, p = 0.015, η_p² = 0.315, β=.722), vertical jump height (F_1,16 = 6.168, p = 0.024, η_p² = 0.278, β=0.645), and performed more pull-ups (F_1,16 = 12.199, p = 0.003, η_p² = 0.433, β=0.906). There were no significant differences in any of the fitness measures between firefighters reporting high compared to low physical quality of life. A secondary analysis found there was a negative association between mental and physical health (r = –0.419, p < 0.05).

Table 1
Descriptive statistics

Variable Mean Standard deviation Minimum Maximum

Demographics

Sex (M:F) 21 : 2 – – –

Age (years) 36.8 7.1 23 49

Years of service (years) 8.7 6.6 1 26

Height (cm) 177.0 5.7 166.5 190.0

Mass (kg) 88.2 16.0 66.2 139.9

Fitness parameters

Bodyfat (%) 25.88 7.35 7.50 40.80

Fat-free mass (kg) 65.75 11.45 48.01 92.50

Fat mass (kg) 23.58 9.50 12.36 57.00

Sit and reach (cm) 31.72 9.40 14.50 48.50

Vertical jump (m) 0.55 0.12 0.36 0.75

1RM Bench Press (kg) 89.84 25.37 36.36 143.18

Pull-ups (reps) 7.74 5.89 0.00 20.00

Push-ups (reps) 32.78 12.99 11.00 60.00

Plank (sec) 101.79 41.18 36.00 220.00

1 mile run (sec) 491.91 67.77 415.00 638.00

YBT 100.20 5.76 89.33 112.19

Quality of life

Physical health composite 54.97 4.34 47.12 63.96

Mental health composite 46.51 7.51 32.79 58.09

Physical functioning 97.61 3.95 90.00 100.00

Physical role functioning 94.57 14.99 50.00 100.00

Bodily pain 79.96 13.25 51.00 100.00

General health 75.39 13.35 47.00 100.00

Vitality 58.91 21.58 0.00 85.00

Social functioning 92.39 12.91 50.00 100.00

Emotional role functioning 91.30 18.03 33.33 100.00

Mental health 79.48 9.97 64.00 96.00

Variable	Mean	Standard deviation	Minimum	Maximum
Demographics
Sex (M:F)	21 : 2	–	–	–
Age (years)	36.8	7.1	23	49
Years of service (years)	8.7	6.6	1	26
Height (cm)	177.0	5.7	166.5	190.0
Mass (kg)	88.2	16.0	66.2	139.9
Fitness parameters
Bodyfat (%)	25.88	7.35	7.50	40.80
Fat-free mass (kg)	65.75	11.45	48.01	92.50
Fat mass (kg)	23.58	9.50	12.36	57.00
Sit and reach (cm)	31.72	9.40	14.50	48.50
Vertical jump (m)	0.55	0.12	0.36	0.75
1RM Bench Press (kg)	89.84	25.37	36.36	143.18
Pull-ups (reps)	7.74	5.89	0.00	20.00
Push-ups (reps)	32.78	12.99	11.00	60.00
Plank (sec)	101.79	41.18	36.00	220.00
1 mile run (sec)	491.91	67.77	415.00	638.00
YBT	100.20	5.76	89.33	112.19
Quality of life
Physical health composite	54.97	4.34	47.12	63.96
Mental health composite	46.51	7.51	32.79	58.09
Physical functioning	97.61	3.95	90.00	100.00
Physical role functioning	94.57	14.99	50.00	100.00
Bodily pain	79.96	13.25	51.00	100.00
General health	75.39	13.35	47.00	100.00
Vitality	58.91	21.58	0.00	85.00
Social functioning	92.39	12.91	50.00	100.00
Emotional role functioning	91.30	18.03	33.33	100.00
Mental health	79.48	9.97	64.00	96.00

Abbreviations: Y-balance test, YBT; RM, repetition maximum; QoL, quality of life.

Table 2

Fitness parameters and health related quality of life measures

		Physical health			Mental health
Fitness measure	QoL group	Mean (SD)	p-value	$ɛ_{ρ}^{2}$	Mean (SD)	p-value	$ɛ_{ρ}^{2}$
Bodyfat (%)	Low	27.5 (5.8)	0.369	0.051	23.0 (8.6)	0.003**	0.423
	High	24.4 (8.5)			28.5 (5.1)
Fat-free mass (kg)	Low	64.7 (10.0)	0.442	0.037	67.8 (14.1)	0.015*	0.215
	High	66.7 (13.0)			63.9 (8.7)
Fat mass (kg)	Low	24.4 (5.8)	0.722	0.008	21.5 (12.4)	0.036*	0.247
	High	22.8 (12.2)			25.5 (5.6)
Sit and reach (cm)	Low	31.7 (9.6)	0.537	0.024	32.0 (10.5)	0.874	0.002
	High	31.8 (9.7)			31.5 (8.7)
Vertical jump (m)	Low	0.55 (0.12)	0.899	0.001	0.6 (0.13)	0.024*	0.278
	High	0.54 (0.12)			0.5 (0.11)
1RM Bench Press (kg)	Low	96.3 (28.6)	0.156	0.122	96.7 (31.3)	0.197	0.102
	High	83.9 (21.6)			83.6 (17.5)
Pull-ups (reps)	Low	7.8 (5.9)	0.899	0.001	10.5 (6.4)	0.003**	0.433
	High	7.7 (6.1)			5.3 (4.2)
Push-ups (reps)	Low	35.2 (13.5)	0.218	0.093	35.3 (15.6)	0.526	0.026
	High	30.6 (12.7)			30.5 (10.2)
Plank (sec)	Low	106.2 (51.8)	0.464	0.034	96.4 (30.8)	0.325	0.060
	High	97.8 (30.3)			106.7 (49.8)
1 mile run (sec)	Low	484.6 (65.1)	0.910	0.001	485.2 (78.9)	0.332	0.059
	High	498.7 (72.4)			498.1 (58.7)
YBT	Low	100.5 (5.2)	0.130	0.137	100.4 (5.4)	0.590	0.019
	High	100.0 (6.4)			100.0 (6.3)

Abbreviations: Y-Balance Test, YBT; RM, repetition maximum; QoL, quality of life. *p < 0.05; **p < 0.01.

4 Discussion

To our knowledge the present study is the first to investigate effects of fitness parameters on firefighter physical and mental health. The findings suggest that the significant differences between mental health groups existed primarily for body composition measures and not other physical fitness measures. Although vertical jump and pull-up performance were significantly different between mental health groups both of these tests have been found to be influenced by body composition [28, 29]. Additionally there were no differences between any fitness measures between high and low physical health groups. Altogether the findings contradicted our original hypotheses. The lack of differences in fitness measures between the physical health groups supports that firefighter self-perception of their physical health is not a product of actual fitness.

The current findings indicate that fitter firefighters do not necessarily receive the mental health benefits of physical activity as the general population. Fitter firefighters may have greater psychological burden compared to lower fit firefighters due to unequal work distribution as lower levels of fitness and greater body fat percentage has been found to be significantly associated with absenteeism [31]. Furthermore, obese firefighters are reported to be 5 times more likely to suffer musculoskeletal injury than normal weight firefighters [32]. Thus it would appear likely that while greater levels of fitness are beneficial for performing the occupational duties of a firefighter an unintended consequence could be increased exposure to traumatic events leading to worsened mental health.

To our knowledge there are no directly comparable studies to ours. Soteriades and colleagues examined the influence of physical activity on occupational stress in firefighters [33]. The authors found an inverse, dose-response relationship as greater levels of physical activity were associated with lower levels of occupational stress. It must be noted that physical activity and fitness are not the same such that one could be classified as physically active yet have relatively low levels of fitness. Another study by Sloan et al. investigated cardiovascular fitness levels and HRQoL of 705 males in the United States Navy [34]. The authors report greater levels of fitness were positively associated with improved quality of life [34].

In regards to no differences in fitness measures between the high and low physical QoL groups we offer a potential explanation. As previously mentioned firefighters may perceive themselves to be physically fit due to the physical demands of their occupation as well as comparing to age-matched peers in non-firefighter professions. Indeed numerous components of fitnesss are associated with performance on firefighter ability tests [35] thus it is likely that firefighters would perceive themselves to be fit if able to perform their occupational duties. This postulation is supported by the theory of planned behavior, which states an individual’s intentions reflect the probability to engage in healthy lifestyle behaviors [36]. An individual’s intentions are influenced by their perceived behavioral control based on the level of ease or challenge of a certain behavior [37]. This theory supports individuals will engage in healthy lifestyle behaviors only if it will lead to a desired outcome. This suggests if low fit firefighters are able to complete occupational tasks they may not believe they need to engage in a structured exercise plan to improve their health and wellness.

An interesting finding from the present study is the possibility that to manage the psychological stress it is feasible fitter firefighters may use exercise as a coping mechanism. As previously mentioned Soteriades et al. found that firefighters turn to physical activity to alleviate occupational stress [33]. For those choosing exercise as their primary coping mechanism improvements in body composition would be expected as found in the present study. Strong et al. supported this theory, stating that male participants reported greater self-efficacy of coping with stressors on days they exercised [38].

The study is not without limitations. Arguably the main limitation was the small sample size. All firefighter participation was voluntary and as a result, when compared to the current literature, our sample may not be generalizable to all firefighters within the department we recruited from. From conversations with leadership within the fire department it was decided participants would provide more accurate responses to quality of life surveys if confidentiality of responses was ensured. Thus we decided to conduct the study at our laboratory as opposed to at the fire department facilities which would have resulted in a larger sample. Future research should focus on working with local firefighter departments to recruit a representative sample of the entire firefighter population to improve the generalizability of research findings. Secondly, including firefighting occupational tasks (i.e., stair climb, hose drag, equipment carry) may have provided more insight to the capacity of our participants to perform job-specific duties. While general fitness assessments are associated with the ability to perform common firefighter duties, they may limit the generalizability of our findings to actual firefighting demands. Lastly, there are limitations (i.e. recall bias, social desirability bias, etc.) when using self-reported measures of HRQoL from participants.

5 Conclusions

Practitioners (i.e. strength and conditioning coaches, athletic trainers, health and wellness coordinators, peer fitness trainers) working with firefighters to improve physical fitness needed for occupational performance should be aware non-fitness factors (i.e. sleep, exposure to traumatic events, non-work interpersonal relationships) may need to avoid the assumption that physical fitness is synonymous with mental and physical health. Some firefighters may use exercise as a coping mechanism for psychological stress and practitioners should be cognizant that physical fitness is not the sole determinant of health and wellbeing. As such to promote physical and mental HRQoL a holistic approach, utilizing an interdisciplinary team of allied health professionals is advised.

Footnotes

Acknowledgments

The authors have no acknowledgments.

Ethical approval

Approval was granted by the George Mason University Institutional Review Board (IRB #: 1389424-1).

Informed consent

Informed consent was obtained from all participants involved in the study.

Conflict of interest

The authors declare that they have no conflict of interest.

Funding

The authors report no funding.

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