Heart Rate Reactivity to Acute Mental Stress is Associated With Parasympathetic Withdrawal and Adiposity in Firefighters

Mendes, Haissa A.; Canto, Natália E.; Lima, Luiz Rodrigo A.; Speretta, Guilherme F.

doi:10.36660/ijcs.20210234

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International Journal of Cardiovascular Sciences

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ORIGINAL ARTICLE • Int J Cardiovasc Sci 37 • 2024 • https://doi.org/10.36660/ijcs.20210234 copy

Heart Rate Reactivity to Acute Mental Stress is Associated With Parasympathetic Withdrawal and Adiposity in Firefighters

Authorship SCIMAGO INSTITUTIONS RANKINGS

Central Illustration
: Heart Rate Reactivity to Acute Mental Stress is Associated With Parasympathetic Withdrawal and Adiposity in Firefighters

Abstract

Background

Firefighters are regularly exposed to stress and have a high incidence of cardiovascular events. Investigating cardiovascular and autonomic reactivity to acute mental stress (AMS) and its association with adiposity may contribute to explaining the increased cardiovascular risk in these professionals.

Objectives

To evaluate cardiovascular and autonomic reactivity to AMS in firefighters while considering adiposity parameters.

Methods

This study recorded the blood pressure and heart rate (HR) of twenty-five firefighters (38±8 years) at rest, while performing the Stroop color-word test to induce AMS, and recovery. Cardiac autonomic modulation (HR variability), baroreflex sensitivity (BRS — sequential method), and adiposity (electrical bioimpedance) were assessed. One-way or two-way analysis of variance followed by Tukey’s post hoc test and multiple linear regression were performed. The significance level was P<0.05.

Results

The AMS increased mean arterial pressure (MAP — Δ16±13 mmHg) and HR (Δ14±7 bpm) ( P <0.05). These responses were associated with parasympathetic modulation withdrawal (RMSSD: baseline: 29.8±18 vs. AMS: 21.5±14 ms; High-frequency: baseline: 5.2±1.4 vs. AMS: 4.5±1.3 Ln ms ² ; P <0.05) and decreased in the Up gain of the baroreflex (baseline: 8.9±5.1 vs. AMS: 6.3±3.0 mmHg/ms; P <0.05). Groups divided by HR reactivity peak showed parasympathetic modulation withdrawal only in firefighters with lower adiposity (RMSSD: baseline: 27.8±17.6 vs. AMS: 14.4±9.2 ms; High-Frequency: baseline: 5.3±1.2 vs. AMS: 3.8±1.4 Ln ms ² ; P <0.05). Fat percentage (β = -0.499), BRS (β = 0.486), and sympathetic/parasympathetic balance (β = -0.351) were predictors of HR reactivity ( P <0.05).

Conclusion

Our results demonstrated that HR reactivity to AMS modulated by cardiac vagal withdrawal seems to be influenced by body composition in this group of firefighters.

Body Composition; Heart Rate; Psychological Stress; Firefighters

	Mean (SD)
Age (years)	38.6(8.8)
Time working at MFB (years)	14.7(10.2)
Anthropometry
Height (m)	1.7(0.1)
Body mass (Kg)	82.8(13.2)
BMI (Kg/m ² )	27.4(3.9)
WC (cm)	94.7(9.0)
WHtR (cm/m)	54.5(5.0)
Body Composition
Body fat (%)	22.0(4.8)
Free fat mass (Kg)	64.2(8.7)
Fat mass (Kg)	18.6(6.5)
Baseline cardiovascular parameters
SAP (mmHg)	135.0(11.1)
DAP (mmHg)	77.6(8.7)
MAP (mmHg)	97.2(8.3)
HR (bpm)	70.9(14.7)
DASS-21
Depression	5.7(9.2)
Anxiety	5.0(6.2)
Stress	10.4(9.0)
Perceived stress and efficiency during AMS
Perceived stress	1.6(0.9)
Efficiency (%)	79(21)

	Baseline	AMS	Recovery	F-value	P -value
Autonomic modulation
RMSSD (ms)	29.8(18)	21.5(14) ^a	31.9(21) ^d	17.5	<0.001
LF (Ln ms ² )	7.0(0.9)	5.9(1.2) ^a	7.2(1.0) ^d	40.0	<0.001
HF (Ln ms ² )	5.2(1.4)	4.5(1.3) ^a	5.3(1.3) ^d	10.3	0.001
LF (nu)	79.7(10.9)	77.9(9.5)	82.6(8.5)	2.4	0.10
HF (nu)	20.2(10.9)	22.0(9.5)	17.4(8.4)	2.4	0.10
LF/HF	6.9(3.8)	5.7(3.1)	8.2(4.6)	3.0	0.06
BRS
Up Gain (mmHg/ms)	8.9(5.1)	6.3(3.0) ^a	8.9(5.5) ^d	5.5	0.01
Down Gain (mmHg/ms)	9.0(5.6)	7.5(3.1)	8.4(5.9)	1.0	0.34
Total Gain (mmHg/ms)	9.0(5.3)	6.9(2.5)	8.7(5.4)	3.0	0.08

	L-HRr	M-HRr	H-HRr	F-value	P-value
DASS-21
Depression	12.8(15.1)	3.8(5.4)	2.2(2.2)	3.1	0.06
Anxiety	9.4(10.5)	4.2(3.5)	2.5(2.0)	2.6	0.09
Stress	15.4(13.5)	9.2(5.4)	7.0(6.2)	1.9	0.17
Perceived stress and efficiency during AMS
Perceived stress	1.3(0.5)	1.8(1.0)	1.8(1.0)	0.6	0.52
Efficiency (%)	78(27)	74(21)	87(12)	0.8	0.43

	ΔHR peak* (dependent variable) model R ² = 0.48
Independent Predictors	β (CI 95%)	β _standardized	P-value
Age (years)	-0.041(-0.085; 0.003)	-0.35	0.06
BRS (ms/mmHg)	0.08(0.14; 0.02)	0.48	0.01
Body fat (%)	-0.09(-0.16; -0.02)	-0.49	0.01
LF/HF ratio	-0.027(-0.054; -0.005)	-0.35	0.04
	ΔMAP peak (dependent variable) model R ² = 0.29
Independent Predictors	β (CI 95%)	β _standardized	P-value
Age (years)	0.34(-0.01; 0.71)	0.42	0.06
Baseline MAP (mmHg)	-0.51(-0.93; -0.09)	-0.59	0.02
BRS (ms/mmHg)	0.47(-0.08; 1.04)	0.40	0.09
Body fat (%)	-0.41(-1.00; 0.17)	-0.30	0.16
LF/HF ratio	0.20(-0.02; 0.43)	0.36	0.08

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[1] Mailing Address: Guilherme Speretta. Federal University of Santa Catarina. Campus Universitario, s/n. Postal code: 88040-900 Florianópolis, SC – Brazil. E-mail: guilherme.speretta@ufsc.br