Resilience, Psychological Stress, Physical Activity, and BMI among United States Air National Guardsmen: The COVID-19 Pandemic

Background

Military service members carry the responsibility to maintain physical and psychological readiness. As such, it is critical for researchers to begin unravelling the widespread impact of the COVID-19 pandemic on service member’s mental and physical wellbeing. The aim of this research was to investigate the complex relationships between BMI, physical activity, psychological stress and resilience among United States Air National Guardsmen (USANG), specifically during the pandemic.

Methods

An online survey was distributed to USANG members. The survey included measures of resilience (CD-RISC-25), perceived psychological stress (PSS), perceived psychological stress brought on by COVID-19 (COVID-19 PSL), current levels of physical activity (IPAQ-SF), perceived impact on physical activity brought on by COVID-19 (COVID-19 PAL), and BMI. Pearson’s correlation coefficients (r) were used to assess correlation significance (α ≤ 0.05), direction, and magnitude.

Results

A total of 110 responses met inclusion criteria for data interpretation. A majority reported a decline in physical activity 54.5%, while 60% reported an increase in psychological stress. According to BMI classifications, 60.9% were considered overweight or obese. Seven meaningful (effect size ≥ |2.0|) and statistically significant salient associations were identified resilience-PSS r = -0.38; resilience-COVID-19 PAL r = 0.21; PSS-COVID-19 PSL r = 0.35; PSS-COVID-19 PAL r = -0.23; COVID-19 PSL COVID-19 PAL r = -0.24; IPAQ-SF-BMI r = -0.23; BMI-Covid-19 PAL r = -0.32.

Conclusion

Key outcomes suggest resilience is inversely associated with assessed and perceived stress, resilience may influence health-related behaviour which subsequently might aid as a protective factor against psychological stress. Knowledge regarding the relationships between the aforementioned variables may help inform decisions by military leadership regarding future lockdowns.

Impact of simulated military operational stress on executive function relative to trait resilience, aerobic fitness, and neuroendocrine biomarkers

PURPOSE

To study the impact of 48 h of simulated military operational stress (SMOS) on executive function, in addition to the role of trait resilience (RES) and aerobic fitness (FIT) on executive function performance. Associations between executive function and neuropeptide-Y (NPY), brain-derived neurotropic factor (BDNF), insulin-like growth factor-I (IGF-I), oxytocin, and α-klotho (klotho) were assessed to elucidate potential biomarkers that may contribute to cognitive performance during a multi-factorial stress scenario.

METHODS

Fifty-four service members (SM) (26.4 ± 5.4 years, 178.0 ± 6.5 cm, 85.2 ± 14.0 kg) completed the 5-day protocol, including daily physical exertion and 48 h of restricted sleep and caloric intake. Each morning subjects completed a fasted blood draw followed by Cognition, a 10-part cognitive test battery assessing executive function. SMs were grouped into tertiles [low (L-), moderate (M-), high (H-)] based on Connor Davidson Resilience Score (RES) and V˙O_2peak (FIT). Repeated measures ANOVA were run to analyze the effect of day on cognitive performance and biomarker concentration. Separate two-way mixed ANOVAs were run to determine the interaction of group by day on cognitive function. Friedman test with Bonferroni-corrected pairwise comparisons were used if assumptions for ANOVA were not met. Associations between changes in biomarkers and cognitive performance were analyzed using parametric and non-parametric correlation coefficients.

RESULTS

SMOS reduced SM vigilance -11.3% (p < 0.001) and working memory -5.6% (p = 0.015), and increased risk propensity +9.5% (p = 0.005). H-RES and H-FIT SMs demonstrated stable vigilance across SMOS (p > 0.05). Vigilance was compromised during SMOS in L- and M-RES (p = 0.007 and p = 0.001, respectively) as well as L- and M-FIT (p = 0.001 and p = 0.031, respectively). SMOS reduced circulating concentrations of α-klotho -7.2% (p = 0.004), NPY -6.4% (p = 0.001), and IGF-I -8.1% (p < 0.001) from baseline through the end of the protocol. BDNF declined -19.2% after the onset of sleep and caloric restriction (p = 0.005) with subsequent recovery within 48 h. Oxytocin remained stable (p > 0.05). Several modest associations between neuroendocrine biomarkers and cognitive performance were identified.

CONCLUSION

This study demonstrates H-FIT and H-RES may buffer the impact of SMOS on vigilance. SMOS negatively impacted circulating neuroendocrine biomarkers. While BDNF returned to baseline concentrations by the end of the 5 d protocol, NPY, IGF-I, and α-klotho may require a longer recovery period. These data suggest that the military may benefit by training and/or selection processes targeting at augmenting trait resilience and aerobic fitness for increased readiness.