US Army basic combat training alters the relationship between body mass index and per cent body fat

Introduction/backgroundAs a proxy for adiposity, body mass index (BMI) provides a practical public health metric to counter obesity-related disease trends. On an individual basis, BMI cannot distinguish fat and lean components of body composition. Further, the relationship between BMI and body composition may be altered in response to physical training. We investigated this dynamic relationship by examining the effect of US Army basic combat training (BCT) on the association between BMI and per cent body fat (%BF).MethodsBMI and %BF were measured at the beginning (week 1) and end (week 9) of BCT in female (n=504) and male (n=965) trainees. Height and weight were obtained for BMI, and body composition was obtained by dual X-ray absorptiometry. Sensitivity and specificity of BMI-based classification were determined at two BMI thresholds (25 kg/m2 and 27.5 kg/m2).ResultsA progressive age-related increase in fat-free mass index (FFMI) was observed, with an inflection point at age 21 years. In soldiers aged 21+, BMI of 25.0 kg/m2 predicted 33% and 29% BF in women and 23% and 20% BF in men and BMI of 27.5 kg/m2 predicted 35% and 31% BF in women and 26% and 22% BF in men, at the start and end of BCT, respectively. Sensitivity and specificity of BMI-based classification of %BF were poor. Soldiers below BMI of 20 kg/m2 had normal instead of markedly reduced %BF, reflecting especially low FFMI.ConclusionsBCT alters the BMI–%BF relationship, with lower %BF at a given BMI by the end of BCT compared with the beginning, highlighting the unreliability of BMI to try to estimate body composition. The specific BMI threshold of 25.0 kg/m2, defined as ‘overweight’, is an out-of-date metric for health and performance outcomes. To the extent that %BF reflects physical readiness, these data provide evidence of a fit and capable military force at BMI greater than 25.0 kg/m2.

Serological and RT-PCR surveillance for COVID-19 in an asymptomatic U.S. Army trainee population

Background Significant variability exists in the application of infection control policy throughout the United States (U.S.) Army initial entry training environment. To generate actionable information for the prevention of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)/coronavirus disease 2019 (COVID-19) transmission among new recruits, active enhanced surveillance was conducted for evidence of and exposure to SARS-CoV-2/COVID-19. Methods We serially tested recruits with a reverse transcriptase polymerase chain reaction (RT-PCR) COVID-19 and/or total antibody to SARS-CoV-2 tests at day 0, 14, and week 10 upon arrival for basic combat training at a location in the southern U.S. Results Among 1,403 recruits who were enrolled over a 6 week period from August 25 through October 11, 2020, 84 recruits tested positive by RT-PCR with more than half (55%, 46/84) testing positive at arrival and almost two-thirds (63%, 53/84) also testing seropositive at arrival. Similarly, among an overall 146 recruits who tested seropositive for SARS-CoV-2 during the period of observation, a majority (86%) of tested seropositive at arrival; no hospitalizations were observed among seropositive recruits and antibody response increased at week 10. Conclusions These findings suggest serological testing may complement current test-based measures and provide another tool to incorporate in COVID-19 mitigation measures among trainees in the U.S. Army.

Injuries and Referral Patterns During Basic Combat Training: An Examination of Data From the Certified Athletic Trainer-Forward Program

ABSTRACT Introduction Injuries sustained during basic combat training (BCT) result in large economic costs to the U.S. Army. The inclusion of athletic trainers (ATs) in other military branches has reduced Troop Medical Clinic (TMC) referrals. However, the inclusion of ATs during BCT has yet to be studied. The purpose of this study was to describe the frequency and nature of sick call visits during BCT and determine how the presence of an AT affects referrals to the TMC. Materials and Methods A prospective cohort study was conducted at the Fort Jackson Army Training Center for one calendar year. Soldiers in BCT, aged 18–42, who reported to sick call were included. Independent variables collected included: Soldier demographics (sex and age), visit reason, and provider impression. Training battalions were placed in three conditions: control (CON), full-time medic (FTM), and part-time athletic trainer (PAT). The dependent variable was disposition (referred or returned to duty [RTD]). Frequencies and proportions were calculated. Logistic regression compared conditions while considering the other independent variables. Return on investment was calculated. Results Fourteen thousand three hundred and four visits were documented. Most soldiers were female (n = 7,650; 53.5%) and under 20 years old (n = 5,328; 37.2%). Visits were most commonly due to physical injury (n = 7,926; 55.4%), injuries affecting the knee (n = 2,264; 15.8%) and chronic/overuse conditions (n = 2,031; 14.2%). By condition, the FTM and PAT conditions resulted in 1.303 (95%CI: 1.187, 1.430; P < .001) and 1.219 (95%CI: 1.103, 1.348; P < .001), or 30.3% and 21.9% higher, odds of being RTD compared to the CON condition, respectively. Return on investment was $23,363,596 overall and $2,423,306 for musculoskeletal-related cases. Conclusions Injuries were common in BCT, particularly in females. Soldiers in both the PAT and FTM conditions were more likely to be RTD compared to those in the CON condition. Athletic trainers (ATs) are effective at reducing potentially unnecessary referrals, demonstrating their value as healthcare providers in the BCT environment. Understanding variables associated with recruit disposition may aid medics and ATs in the development of triage protocols and further reduction of potentially unnecessary soldier referrals. The Certified Athletic Trainer-Forward Program resulted in significant return on investment, further supporting the inclusion of ATs in BCT.

Sleep quality and military training injury during basic combat training: a prospective cohort study of Chinese male recruits

ObjectiveTo examine the association between sleep quality and military training injury (MTI) in recruits during basic combat training (BCT).MethodsParticipants were new recruits undergoing 12-week military BCT in China. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI) . Participants were classified into two groups based on their sleep quality (group 1, good sleep, PSQI score <7; group 2, poor sleep, PSQI score ≥7) at the start of BCT. Logistic regression analysis was conducted to test whether baseline PSQI score was associated with MTI incidence during BCT.ResultsA total of 563 participants were included. The incidence of MTI was significantly lower in group 1 (48/203, 23.6%) than in group 2 (150/360, 41.7%) (p<0.001). Logistic regression analysis showed that the odds of MTI were 2.307 times higher in group 2 than in group 1 without adjusting for confounders: OR=2.307, p<0.001. When the model was adjusted for age, ethnicity, educational level and family income (OR=2.285) or for the previous confounders plus body mass index (OR=2.377), the results were similar (both p<0.001). Analysis of the types of initial MTI showed that group 2 had about 2.1 times higher odds of soft tissue injury than group 1 (p<0.001 in all the three models).ConclusionSleep quality before BCT influences the incidence of MTI, especially of soft tissue injury.