Physical activity and exercise patterns of submariners in land and sea environments

Introduction:
Submarine environments pose unique challenges to maintaining physical activity and exercise routines due to confined spaces, demanding schedules, and limited resources. This study investigated submariners’ physical activity patterns, sleep quality, and perceived exercise barriers in both land- and sea-based settings, with the goal of informing targeted health interventions.

Materials and Methods:
Ethics approval was granted by the Defence Science and Technology Group and Edith Cowan University review panels. This cross-sectional study surveyed 21 Royal Australian Navy submariners (25-48 years; 18 male) using a modified version of the International Physical Activity Questionnaire. Participants reported weekly engagement in general physical activity (e.g., walking, moderate- and vigorous-intensity activity) and structured exercise training (high-intensity interval training, moderate-intensity continuous training, and resistance training [RT]), as well as sitting time and sleep duration. Additional items assessed perceived barriers and motivations to exercise, time spent on land and at sea over the past 12 months (9 ± 3 and 3 ± 3 months, respectively), and their longest continuous deployment. Descriptive statistics and paired t-tests were used to compare outcomes between land and sea environments.

Results:
Total physical activity was lower (P < .001) at sea (118 ± 30 minutes/week) compared to land (745 ± 60 minutes/week), with the greatest reductions observed in walking (−86%, P < .001) and moderate-intensity cardiovascular training (−95%, P = .002). High-intensity interval training declined by 81% (P = .006), and RT dropped by 84% (P = .045). Reported barriers at sea included water usage restrictions (57%), limited space (43%), inadequate facilities (43%), time constraints (38%), fatigue (38%), and noise restrictions (19%). Sleep quality declined by 37% at sea (P < .001), though changes in sleep duration were not statistically significant. Sitting time increased by 51% on workdays (P = .014).

Conclusions:
Sea deployments are associated with substantial declines in physical activity and sleep quality among submariners, accompanied by increased sitting time and widespread behavioral disengagement. These findings highlight the need for practical strategies to support health, well-being, and operational readiness in constrained environments. Strengths of the study include context-specific survey design and rich participant engagement, as reflected by detailed qualitative responses. Limitations include small sample size, variability in responses, potential recall bias, and the inability to assess survey reliability because of ethical constraints. Future research should prioritize longitudinal designs and explore implementable interventions to promote physical activity and sleep during deployment. These findings may also apply to other constrained environments, such as naval surface ships, remote field sites, or mining operations, where similar occupational barriers exist. Overall, these results offer valuable insight into how deployment conditions shape health behaviors in submariners and provide a foundation for developing evidence-based strategies to improve activity and well-being in this and similar populations.