Acute Fatigue Responses to Occupational Training in Military Personnel: A Systematic Review and Meta-Analysis

Abstract

Introduction Military personnel are required to undertake rigorous physical training to meet the unique demands of combat, often leading to high levels of physiological stress. Inappropriate recovery periods with these high levels of physical stress may result in sub-optimal training and increased risk of injury in military personnel. However, no reviews have attempted to examine the magnitude of training-induced stress following military training activities. The aim of this systematic review was to assess the magnitude of physiological stress (physical, hormonal, and immunological) following task-specific training activities in military personnel. Methods An extensive literature search was conducted within CINAHL, PubMed, Scopus, SportDiscus, and Web of Science databases with 7,220 records extracted and a total of 14 studies eligible for inclusion and evaluation. Study appraisal was conducted using the Kmet scale. Meta-analysis was conducted via forest plots, with standard mean difference (SMD, effect size) and inter-trial heterogeneity (I2) calculated between before (preactivity) and after (12–96 hours postactivity) military-specific activities for biomarkers of physiological stress (muscle damage, inflammation, and hormonal) and physical performance (muscular strength and power). Results Military training activities resulted in significant levels of muscle damage (SMD = −1.28; P = .003) and significant impairments in strength and power (SMD = 0.91; P = .008) and testosterone levels (SMD = 1.48; P = .05) up to 96 hours postactivity. There were no significant differences in inflammation (SMD = −0.70; P = .11), cortisol (SMD = −0.18; P = .81), or insulin-like growth factor 1 (SMD = 0.65; P = .07) when compared to preactivity measures. Conclusions These findings indicate that assessments of muscle damage, anabolic hormones like testosterone, strength, and power are effective for determining the level of acute stress following military-specific activities. With regular monitoring of these measures, appropriate recovery periods may be implemented to optimize training adaptations and occupational performance, with minimal adverse training responses in military personnel.

Changes in physical performance, body composition and physical training during military operations: systematic review and meta-analysis

“…However, if it had been removed, the pooled effect size value of maximal jumping height or distance would have changed from 0.46 (− 0.59 to 1.52) to 0.00 (− 0.21 to 0.21) and, I 2 value from 95.2 to 0.0%. Several studies have reported decrements in lower body power after strenuous military field exercise 15,58 . This may be due to neuromuscular fatigue combined with loss of muscle mass, the two factors contributing to fast force production ability.…”

“…Acute physical fatigue deteriorate cognitive function, physical performance and critical combat skills such as shooting accuracy [7][8][9][10][11] . In general, dramatic short-term hormonal disturbances and negative changes in body composition as well as physical performance have been reported following demanding military field training 3,[12][13][14][15] .…”

“…Acute physical fatigue deteriorate cognitive function, physical performance and critical combat skills such as shooting accuracy [7][8][9][10][11] . In general, dramatic short-term hormonal disturbances and negative changes in body composition as well as physical performance have been reported following demanding military field training 3,[12][13][14][15] .Occupational physical demands typically increase during military operations. According to Nagai et al 16 , 58% of combat aviation support soldiers carried regularly external loads with an average load of 22 kg during a one-year deployment in Afghanistan.…”

Optimising Combat Readiness: Practical Strategies for Integrating Physiological and Psychological Resilience in Soldier Training

“…Military operations’ demanding endurance requirements underscore the need for elevated cardiovascular fitness. Robust studies have consistently demonstrated that endurance training enhances soldiers’ aerobic capacity and equips them to execute prolonged physical activities with heightened efficiency [ 74 ].…”

Correlation Between the Cardiorespiratory Fitness Level and Habitual Physical Activity in Brazilian Air Force Recruits

“…After being admitted, recruits undergo military training that involves a variety of activities, such as technical learning of the equipment to be used, exhaustive physical training, and technical tactical testing, among other practices. The purpose of this stage is to raise the military to physical stress so that in combat conditions he can adequately respond to operational demands (Orr et al, 2020;Heilbronn et al, 2022). Thus, instruction and physical training is, therefore, one of the pillars of the basic training protocol of all military personnel (Heinrich et al, 2012;Orr & Pope, 2015).…”