Physical activity levels and sleep quality among military aircrew during COVID-19: A questionnaire-based pilot study

INTRODUCTION

Engaging in regular physical activity (PA) promotes positive health outcomes, namely, a decrease in all-cause mortality, cardiovascular disease mortality, hypertension, type-II diabetes, mental health illnesses, and an increase in cognitive health and sleep.^[1,2] The World Health Organization (WHO) recommends an average adult to involve over a week in at least 150–300 min of moderate levels of PA/75– 150 min of vigorous PA.^[2] Good sleep quality is essential for the recovery of body function, relieve work fatigue, and maintain sufficient energy, physical strength, and a healthy mental state as well as an important factor in the assessment of overall health and risk of cardiovascular diseases.^[3] PA level and sleep quality are associated negatively in various studies.^[4,5]

COVID-19 was declared, a pandemic by the WHO on March 11, 2021, and various governments across the globe announced several restrictions to curb the spread of this disease.^[6] These unprecedented restrictions were found to prohibit outdoor activities as well as public gatherings including sports and fitness clubs and group PAs, thereby discouraging individuals to involve in both routine outdoor-based leisure time PA, games/sports, and fitness activities.^[7] Widespread fear, anxiety, and other psychological problems affected the sleep quality of various frontline workers.^[3] During COVID-19 pandemic, PA levels and sleep quality are compromised globally.^[4,8] However, these two factors must be adequately maintained for a good immune function, especially against viral infections.^[9,10] In addition, inadequate PA and disturbed sleep quality are both found to independently make an individual prone to develop obesity, which is suggested to be a key risk factor for poor outcomes in COVID-19 infection.^[11,12]

Adequate PA and sleep quality are also crucial factors for maintaining optimal performance in military aircrew given the physiological demands of alien flying conditions and the occupational stress of the military lifestyle.^[13,14] Aircrew who maintained a high level of PA reported lesser disabilities despite flying in a high-G environment and helped them maintain operational readiness.^[15] The effect of COVID-19 restrictions on PA levels and sleep quality among military aircrew has not been studied. Hence, there was a felt need to study the PA levels and sleep quality among the military aircrew during the COVID-19 pandemic. This pilot study aimed at assessing the PA and sleep quality among military aircrew during COVID-19 pandemic using questionnaire based survey.

MATERIAL AND METHODS

A cross-sectional pilot survey was conducted among the aircrew of a training establishment in July 2021 after obtaining permission from the head of the institute. The aerospace medicine specialist of the center explained the participants about the study as well as instructions on filling out the questionnaire and only volunteering subjects participated in the questionnaire based survey. Participants’ identity was not included in the questionnaire to maintain the anonymity of the data and each response was given a unique ID by the investigator. The coded responses were then analyzed by the co-investigators to ensure complete anonymity and blinding. Fifty-nine aircrew (Weight: 68.7 ± 6.45 kg and body mass index [BMI]: 22.6 ± 1.76 kg/m²) participated in this pilot survey. All the volunteered participants returned the filled questionnaire with responses. The participants included instructors/trainee aircrew and one female aircrew. All aircrew who were medically fit and who were not suffering from any sleep disorders or any other ailments in the previous 7 days of the conduct of survey were included in the study.

The questionnaire included three parts namely demographic characteristics, PA level assessment, and sleep quality assessment. Demographic characteristics included were age categories, gender, weight, height, and instructor/trainee detail, flying experience in months, whether an individual was currently involved in flying, whether individual participated in sports events/games regularly in the past 2 years and whether the participant was involved in regular PA before pandemic as per the WHO guidelines.^[2] The second part consisted of an assessment of PA level using validated International Physical Activity Questionnaire – Short Form (IPAQ-SF) in English with a final question of self-rating of the PA level before the pandemic in comparison to the answered questions. The final part of the questionnaire included the validated Pittsburgh Sleep Quality Index (PSQI) comprising 07 components namely subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Similar to the second part, this section also included a final question of self-rating of the PA level before the pandemic in comparison to the answered questions.

PA levels, namely, vigorous, moderate, and walking were converted into minutes per week. Total PA MET minutes as minutes/week were calculated using IPAQ short form scoring protocol.^[16] One MET is the metabolic equivalent of oxygen consumption at rest. A MET-minute quantifies the oxygen consumption during the PA in METs for the given duration for doing that particular PA level.^[17] The subjective sleep quality global index score, that is, the Global PSQI score comprising seven components was computed using the PSQI protocol.^[18] PSQI score ≤5 was considered as good sleep and >5 was considered poor sleep.^[3]

Summary statistics percentages, median, and inter-quartile range (IQR) were used to describe the PA scores, Kilocalories, and PSQI by characteristics of respondents. Shapiro–Wilk’s test was applied to test the normality of continuous variables. Mann–Whitney U test and Kruskal–Wallis test were used to study the differences in PSQI score, MET duration and Kilocalories of PA among study respondents. Chi-square and Fisher’s exact test were used to test the association factors associated with the PA and PSQI levels. Statistical significance was set at P ≤ 0.05. All the data analysis was done in Stata 12.1 (Stata Corp LP, Texas, USA).

RESULTS

A total of 59 respondents, including eight aircrew instructors and 51 aircrew trainees participated in the survey. About 78% of participants were <25 years of age. Only one female trainee aircrew participated in the study. About 90% of respondents were actively involved in flying activities currently. About 45.8% had a flying experience of <6 months and 42.4% between 6 and 18 months. About 80% of participants reported that they had been participating in games/sports events in the past 2 years. Games/sports events played included volleyball (28%), football (25%), basketball (15%), badminton (13%), cricket (9%), running (6%), tennis (2%), and hockey (2%). About 88.1% of respondents reported that they were involved in regular PAs before the COVID-19 pandemic and 57.6% of participants self-rated that they were doing a high level of PA before the pandemic as compared to during the study. About 44.2% of respondents reported good quality of sleep, while only 6.8% reported bad quality sleep before the pandemic. [Table 1] depicts the demographic characteristics and their distribution among respondents.

[Table 2] shows the comparison of PA levels, namely, vigorous, moderate, walking, or sitting in MET-duration, that is, MET minutes/week, the total PA in Kilocalories, and Global PSQI score with the demographic characteristics. Aircrew trainees were found to be engaging significantly less in moderate PA (P = 0.001) and walking (P = 0.037), thus spending 954 (480, 1674) MET minutes/week, which was significantly lower than the total PA of instructors (P = 0.013). The sitting time in instructor’s aircrew was significantly lower, that is, 3 (2, 5) h/day (P < 0.0001). Calories expenditure was also significantly higher in the instructor aircrew than in the trainee aircrew (P = 0.010).

Respondents with a flying experience of more than 18 months were found to significantly involve more in moderate PA (P = 0.009) and engage less in sitting activities (P = 0.002). The respondents who were actively involved in flying were found to expend much higher calories (P = 0.050) with less sitting time (P = 0.005) than those who were not currently flying. Aircrew who participated in sports events/games in the past 2 years were found significantly engaging in higher PA amounting to 1547 (827, 1911) MET minutes/week and energy expenditure of 1752.7 (922.93, 2070.25) Kcal/week (P < 0.0001).

The participants who responded that they engaged regularly in PA before the pandemic were found to be involved in longer sitting time, that is, 6 h/day (IQR = 6, 10) (P = 0.032) during the conduct of the study. Respondents who rated that they were engaged in a high level of PA before the pandemic were found to spend fewer calories, that is, 1001.25 (IQR = 673.2, 1794)/week during the study period (P = 0.042). The global PSQI score significantly differed among the respondents who rated low, moderate, or high PA before the pandemic (P = 0.025).

[Table 3] shows the comparison between PSQI components and PA levels. Respondents who reported bad subjective sleep quality were significantly spending less time in vigorous (P = 0.014) and moderate (P = 0.004) activities leading to a significantly lower total PA of 377 (93, 834) MET-minutes/week than other respondents (P = 0.010). These aircrews with bad sleep had significantly longer sitting time of 10 h/day (P = 0.026) and fewer calories expenditure of 452.4 (102.3, 1000.8) Kcal/week than the respondents with good sleep (P = 0.013). Bad sleep latency was also significantly associated with the lower duration of moderate level PA of 60 (8, 90) MET-minutes/week (P = 0.038). [Figures 1 and 2] show the global PSQI score wise total PA Kilocalories and total PA MET duration (min/week).

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Figure 1:

Physical activity in Kilocalories and global PSQI score of military aircrew. PSQI: Pittsburgh sleep quality index.

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Figure 2:

Physical activities in MET (min/week) and global PSQI score of military aircrew. PSQI: Pittsburgh sleep quality index.

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DISCUSSION

This pilot survey aimed to assess the level of PA and sleep quality among military aircrew during the COVID-19 pandemic in a fighter-training establishment. The research idea demonstrated is novel in this field, to the best of our knowledge, given the importance of both PA levels and sleep in flying performance, military operational readiness as well as in augmenting one’s immunity in the fight against COVID-19 and the lack of adequate studies in literature.

Respondents were predominantly young male trainee aircrew in the early years of their active flying career maintaining well within their accepted range for body composition, that is, BMI: 22.6 ± 1.76 kg/m² [Table 1]. More than 80% of the aircrew were involved in either regular PA as per the WHO recommendation, that is, at least 150 min of PA in a week or engaged in sports or events before the pandemic. Self-rating of PA level as compared to the present response on PA levels and sleep quality showed that about 68% of aircrew did moderate to a high level of PA and more than 93% of aircrew had fairly good to good sleep quality before the pandemic. This indirectly depicts the knowledge, attitude, and practice of aircrew concerning the need to incorporate PA regularly for maintaining health, and fitness, and thereby enhance flying performance.

CONCLUSION

PA levels have been affected by the COVID-19 pandemic among military aircrew. However, aircrew who regularly engaged in sports/games managed to involve in moderate to vigorous PA despite the restrictions. Aircrew with better sleep quality was found significantly engaging in higher PA levels and lesser sitting time. Sedentary behavior was assessed as sitting time increased in trainee aircrew, aircrew who were not involved in active flying and in aircrew with bad sleep quality.

The observed difference between the instructor aircrew and trainee aircrew as well as based on flying experience and age categorization in all the PA parameters, namely, PA levels, total PA MET-min/week, and Kcal/week as well as sitting time may not be representative due to unequal sample distribution. However, future studies might provide insight into the differences. This study being a pilot cross-sectional study of a single center military aircrew, the findings of this study cannot be generalized. Even though the validated IPAQ-SF scoring protocol adjusts the over-reported PA levels and underestimated sitting time, the limitations of recall bias and lack of matched-control groups are the limitations of this subjective survey. However, the preliminary findings of this pilot study are indicating the need to conduct detailed robust research involving a large sample of military aircrew cohort incorporating other confounders to comprehend their PA levels and sleep quality better and to plan appropriate preventive and promotive strategies if required.