Beyond High-Intensity Interval Training: Optimizing Endurance Training Intensity Distribution to Enhance Warfighter Aerobic Fitness

Physical fitness is a key modifiable determinant of warfighter operational readiness. Although warfighters must develop a broad spectrum of physical fitness components, a strong body of evidence suggests that aerobic fitness fundamentally underpins military-occupational task performance. Furthermore, evidence suggests that chronic exposure to a high-volume of endurance training can confer enhanced physiological and psychological robustness and may also enhance cognitive function. Despite the recognized importance of aerobic fitness, an increased emphasis on the concept of the anaerobic battlefield has led many military physical training (PT) programs to prioritize high-intensity interval training (HIIT) over high-volume, low-intensity endurance training (HVLIT). This shift may have inadvertently compromised the development of aerobic fitness and psychological robustness within warfighter populations. Therefore, this raises several important questions: How do successful endurance athletes train? And how might this knowledge be applied to enhance military PT? Based on the available evidence, it is recommended that military PT programs should be based on a suitable periodization model incorporating concurrent strength and endurance training. To enhance aerobic fitness, the use of HVLIT should be prioritized with HIIT strategically integrated through the use of either a polarized (80/20%) or a pyramidal (70/20/10%) training intensity distribution model.