Physical and behavioral characteristics of soldiers acquiring recommended amounts of sleep per night.

OBJECTIVES: Only one-third of U.S. Army Soldiers meet the recommended sleep guideline of 7 or more hours per night. Soldiers meeting the recommended sleep guideline are more likely to perform better on cognitive and physical tasks. The purpose of this analysis was to compare the physical and behavioral characteristics of Soldiers who met and did not meet the sleep recommendation guideline and determine associations between physical and behavioral characteristics and the acquisition of recommended amounts of sleep per night. METHODS: A survey was administered to U.S. Army Soldiers. Adjusted odds ratios and corresponding 95% confidence intervals were calculated to determine associations between achieving the recommended number of hours of sleep per night and age, physical characteristics, health behaviors, physical training, and physical performance. RESULTS: A survey was completed by 4229 men and 969 women. Male Soldiers who met the recommended sleep requirement had lower estimated body fat [20.3 ± 4.2% vs. 21.1 ± 4.4%], were less likely to use tobacco [11.5% vs. 16.2%] and exercised more [259 ± 226 vs. 244 ± 224 min/wk] compared with those who did not obtain 7 hours of sleep per night. Female Soldiers who met the recommended sleep requirement had lower estimated body fat [31.4 ± 4% vs. 32.1 ± 4.6%] and exercised more [258 ± 206 vs. 241 ± 216 min/wk] compared with those who did not obtain 7 hours of sleep per night. CONCLUSION: Soldiers who choose to adopt healthy lifestyle characteristics may be more likely to meet the recommended sleep duration guideline.

Vaping, Smoking, and the Physical Fitness of Active Young Men.

INTRODUCTION: Adverse effects of cigarette smoking on physical performance are well studied. Because of the recent rise in popularity of vaping, it is important to evaluate its effect on fitness both independently and in conjunction with traditional cigarette use. METHODS: This was a secondary analysis performed in 2018 on data collected from U.S. Army Soldiers during 2016. All metrics were self-reported via an electronic questionnaire. Personal characteristics of current ENDS users, smokers, and dual users were compared with a reference group that reported no history of use. Adjusting for age and physical training habits, an ANCOVA was used to compare Army physical fitness test results. A Fisher's exact test determined specific mean differences between groups. RESULTS: This study population consisted of 2,854 men aged 24.6 years on average. Differences in physical training and fitness were shown between the groups. Never users averaged the most total physical training, followed by ENDS users, smokers, and then dual users. Compared with never users on the fitness tests, ENDS users had an adjusted mean difference of +27 seconds on the 2-mile run, -4.56 push-ups, and -2.01 sit-ups; smokers averaged +8 seconds, -2.15 push-ups, and -1.44 sit-ups; and dual users averaged +32 seconds, -5.17 push-ups, and -3.88 sit-ups. Dual users had significantly (p<0.05) lower scores than current smokers and never users on all 3 fitness events. CONCLUSIONS: This study suggests that individuals who use e-cigarettes and tobacco cigarettes average a lower level of fitness than individuals who abstain.

The Combined Effect of Cigarette Smoking and Fitness on Injury Risk in Men and Women.

BACKGROUND: Prior studies have identified cigarette smoking and low fitness as independent risk factors for injury; however, no studies have evaluated the combined effect of cigarette smoking and fitness on injury risk. OBJECTIVE: To evaluate the combined effect of cigarette smoking and fitness on injury risk in men and women. DESIGN: This is a secondary analysis of data collected from US Army recruits (n = 2000) during basic combat training within the United States in 2007. Physical training and fitness, cigarette smoking, and prior injury data were obtained from questionnaires, whereas demographic and injury data were obtained from medical and basic combat training unit records. Chi-squared tests were used to assess differences in injury risk by fitness level and cigarette smoking. Relative risk values were calculated with 95% confidence intervals. RESULTS: The primary findings showed that smokers experienced 20%-30% higher risk of injury than nonsmokers. In addition, higher aerobic and muscular fitness was generally not protective against injury between least fit and more fit smokers. However, higher fitness was protective against injury between least and more fit nonsmokers, with least fit nonsmokers being 30%-50% more likely to experience an injury than fit nonsmokers. CONCLUSION: This study revealed that higher aerobic and muscular fitness was not protective against injury among smokers; however, it was protective against injury among nonsmokers. Further implementation of smoking cessation programs may be beneficial for military and civilian personnel who are required to be physically fit in order to carry out their job responsibilities. IMPLICATIONS: Male and female smokers experienced significantly higher risk of injury than nonsmokers. Although higher fitness is protective against injury in nonsmokers, the protective effect of fitness is lost among smokers. In an attempt to reduce injury risk among military and emergency personnel, smoking cessation programs should be further implemented among both more fit and less fit smokers.

Musculoskeletal training injury prevention in the U.S. Army: Evolution of the science and the public health approach.

Injuries cause more morbidity among soldiers in the U.S. Army than any other health condition. Over two-thirds of U.S. soldiers' injuries occur gradually from cumulative micro-traumatic damage to the musculoskeletal system as a result of physical training activities. Paradoxically, the very physical training activities required to improve soldier performance also result in injury. Determining the amounts and types of physical training that maximize performance while minimizing injuries requires scientific evidence. This evidence must be incorporated into a framework that ensures scientific gaps are addressed and prevention efforts are evaluated. The five-step public health approach has proven to be an effective construct for Army public health to organize and build an injury prevention program. Steps include: 1) surveillance to define the magnitude of the problem, 2) research and field investigations to identify causes and risk factors, 3) intervention trials and systematic reviews to determine what works to address leading risk factors, 4) program and policy implementation to execute prevention, and 5) program evaluation to assess effectiveness. Dissemination is also needed to ensure availability of scientific lessons learned. Although the steps may not be conducted in order, the capability to perform each step is necessary to sustain a successful program and make progress toward injury control and prevention. As with many U.S. public health successes (e.g., seatbelts, smoking cessation), the full process can take decades. As described in this paper, the U.S. Army uses the public health approach to assure that, as the science evolves, it is translated into effective prevention.

Factors Associated With Injury Among Employees at a U.S. Army Hospital.

The purpose of this study was to investigate injury incidence and factors associated with injury among employees at a large U.S. Army hospital to inform injury prevention planning and health promotion education efforts. Demographics, health behaviors, and injury history were collected by survey from hospital employees between October and December 2014. Descriptive statistics were reported and factors associated with injury were determined using multiple logistic regression. Respondents (380; 56% females, 44% males; 54% active duty military, 45% civilians) reported a prevalence of unhealthy behaviors (e.g., not enough exercise [58%] and poor sleeping habits [49%]). Nearly half of respondents (47%) reported at least one occupational injury in the past 12 months. Leading mechanisms of injuries were repetitive overuse (36%), falls (15%), and single twisting movement/overexertion (14%). Leading activities at the time of injury were physical training (24%), walking/hiking (15%), and lifting or moving objects (11%). Factors associated with injury included active duty military status, less education, tobacco use, overuse of alcohol or drugs, and stress. Health education efforts and materials intended for hospital staff should incorporate identified modifiable injury risk factors (e.g., alcohol and drug use, stress, tobacco use, poor sleep). Injury prevention initiatives should focus on physical training, walking/hiking, and lifting. Establishment of surveillance and routine review of employee injury, illness, and health behavior data are recommended to monitor program effects and collect data necessary to inform future prevention priorities and planning.

Effect of Mandatory Unit and Individual Physical Training on Fitness in Military Men and Women.

PURPOSE: The purpose of this study was to look at the effect of additional individual physical training (PT) in addition to mandatory unit PT as well as other risk factors on physical fitness. DESIGN: A cross-sectional design. SETTING: This study was conducted on a US military installation. PARTICIPANTS: Participants were 6290 male and 558 female active duty US Army soldiers in 3 light infantry brigades. MEASURES: Participants completed self-administered questionnaires asking about individual characteristics, PT, and physical fitness. Cut points were established for soldiers scoring within the top 33% for each of the 3 Army Physical Fitness Test events (2-mile run, sit-ups, and push-ups) and top 50% in each of the tests combined for overall performance. ANALYSIS: Odds ratios and 95% confidence intervals from multivariate analyses were calculated. RESULTS: Variables impacting physical fitness performance of men and women included increased body mass index, leading unit PT sessions, and individual distance running mileage. Other variables impacting physical performance for men included increased age, smoking, and individual resistance training. CONCLUSION: Soldiers performing additional individual PT demonstrated a positive influence on fitness compared to unit PT participation alone. Increased age and being overweight/obese negatively influenced physical fitness. To enhance fitness performance through unit PT, running by ability groups and resistance training should be encouraged by leadership.

The Role of Gender and Physical Performance on Injuries: An Army Study.

INTRODUCTION: In basic combat training, women experience twice as many injuries as men; however, evidence at the operational Army level is limited. This study aims to investigate the association between gender and injury likelihood while controlling for certain confounding factors in the operational Army. METHODS: Data were analyzed in 2015 from a cross-sectional study utilizing data from a 2010-2011 survey of light infantry Army Soldiers. Gender, age, body fat, tobacco use, Army Physical Fitness Test (2-mile run, push-ups, and sit-ups), occupational physical demand, and injury data were obtained via paper survey. ORs and 95% CIs from a multivariable analysis were calculated. RESULTS: Surveys were completed by 4,384 male and 363 female Soldiers. Injury incidence was 42% for men and 53% for women. After adjusting for the aforementioned variables, injury likelihood was higher in Soldiers aged ≥27 years (OR [age 27-29/22-26 years]=1.26, 95% CI=1.07, 1.48; OR [age ≥30/22-26 years]=1.28, 95% CI=1.08, 1.51), Soldiers with body fat ≥23.38% (OR [body fat ≥23.38%/≤19.28%]=1.30, 95% CI=1.08, 1.57), and Soldiers with the slowest 2-mile run times (OR [≥15.68/≤14.13 minutes]=1.53, 95% CI=1.26, 1.85). Women were no more likely than men to sustain an injury. CONCLUSIONS: When accounting for age, body fat, physical performance, and occupational physical demand, there was no gender difference in the likelihood of injury among Soldiers. Although women, on average, have lower aerobic and muscular performance than men, results suggest men and women of similar physical performance experience similar injury likelihood.

Physical training, smoking, and injury during deployment: a comparison of men and women in the US Army.

PURPOSE: To investigate changes in physical training (PT), fitness, and injury during deployment and identify differences between men and women. METHODS: Data were collected on male and female US Army Soldiers through self-reported surveys completed before and after deployment to Afghanistan. Changes in physical training activities, physical fitness, injury incidence, BMI, and smoking status were analyzed. Descriptive statistics were used to compare before deployment and deployment results and differences between men and women. RESULTS: Surveys were completed by 727 men and 43 women. The percentage of Soldiers engaging in unit PT running of 5 miles or more per week decreased by almost half for men and women. The percentage of Soldiers doing personal PT running of 5 miles or more per week and engaged in resistance training 3 or more days per week more than doubled for men and women during deployment. Cardiorespiratory endurance for women improved by 50 seconds (P=.06) and for men declined by 29 seconds (P<.01), while muscular endurance increased by 0.6 repetitions (P<.01) during deployment. Injury rates for men decreased, on average, 36.2 to 19.0 injuries per 1,000 Soldiers per month (P=.01). Injury rates for women decreased on average from 42.6 to 14.0 injuries per 1,000 Soldiers per month (P=.02). During deployment, BMI did not change for men or women and smoking increased 19% for men (P<.01), but did not increase for women. CONCLUSION: Comparisons of physical training activities and health behavior among men and women before and during deployment suggests that increased resistance training could be recommended for women and smoking cessation for men. Given the potentially important role of personal PT in maintaining physical fitness in the deployment environment, future work should support provision of the necessary environment and equipment for Soldiers to perform personal PT effectively and safely on their own. Further, the physical training gaps between men and women should be addressed, with suggestions regarding where improvements can be made, especially for women interested in seeking combat positions with high physical demands.

Extreme conditioning programs and injury risk in a US Army Brigade Combat Team.

CONTEXT: Brigades and battalions throughout the US Army are currently implementing a variety of exercise and conditioning programs with greater focus on preparation for mission-specific tasks. An Army physical therapy clinic working with a light infantry brigade developed the Advanced Tactical Athlete Conditioning (ATAC) program. The ATAC program is a unique physical training program consisting of high-intensity aquatic exercises, tactical agility circuits, combat core conditioning, and interval speed training. Along with ATAC, battalions have also incorporated components of fitness programs such as the Ranger Athlete Warrior program and CrossFit (Crossfit, Inc, Santa Monica, CA) an extreme conditioning program (ECP). OBJECTIVE: To determine if these new programs (ATAC, ECP) had an effect on injury rates and physical fitness. DESIGN: Surveys were administered to collect personal characteristics, tobacco use, personal physical fitness training, Army physical fitness test results, and self-reported injuries. Medical record injury data were obtained 6 months before and 6 months after the implementation of the new program. Predictors of injury risk were assessed using multivariate logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were reported. RESULTS: Injury incidence among Soldiers increased 12% for overall injuries and 16% for overuse injuries after the implementation of the ATAC/ECPs. However, injury incidence among Soldiers not participating in ATAC/ECPs also increased 14% for overall injuries and 10% for overuse injuries. Risk factors associated with higher injury risk for Soldiers participating in ATAC/ECPs included: greater mileage run per week during unit physical training (OR (>16 miles per week÷≤7 miles per week)=2.24, 95% CI, 1.33-3.80); higher body mass index (BMI) (OR (BMI 25-29.9÷BMI<25)=1.77, 95% CI, 1.29-2.44), (OR (BMI =30÷BMI<25)=2.72, 95% CI, 1.67-4.43); cigarette use (OR (smoker÷nonsmoker)=1.80, 95% CI, 1.34-2.42); poor performance on the 2-mile run during the Army Physical Fitness Test (APFT) (OR (=15.51 minutes÷≤13.52 minutes)=1.76, 95% CI, 1.13-2.74); Injury risk was lower for those reporting resistance training, (OR (<1 time per week÷none)=0.53, 95% CI, 0.31-0.92), (OR (1-2 times per week÷none)=0.50, 95% CI, 0.29-0.84), (OR (≥3 times per week÷none)=0.45, 95% CI, 0.24-0.85). CONCLUSIONS: Given that Soldiers participating in ATAC/ECPs showed similar changes in injury rates compared to Soldiers not participating in ATAC/ECPs, no recommendation can be made for or against implementation of ATAC/ECPs.

A prospective investigation of injury incidence and risk factors among army recruits in combat engineer training.

BACKGROUND: United States Army combat engineer (ENG) training is an intense 14-week course designed to introduce new recruits to basic soldiering activities, Army values and lifestyle, and engineering skills and knowledge. The present investigation examined injury rates and injury risk factors in ENG training. METHODS: At the start of their training, 1,633 male ENG recruits were administered a questionnaire containing items on date of birth, height, weight, tobacco use, prior physical activity, and injury history. Injuries during training were obtained from electronic medical records and the training units provided data on student graduation and attrition. Risk factors were identified using Cox regression. RESULTS: Ninety-two percent of the recruits successfully graduated from the course and 47% of the recruits experienced one or more injuries during training. Univariate Cox regression demonstrated that recruits were at higher injury risk if they reported that they were older, had a higher or lower body mass index, had smoked in the past, had performed less exercise (aerobic or muscle strength) or sports prior to ENG training, had experienced a previous time-loss lower limb injury (especially if they had not totally recovered from that injury), or had a lower educational level. CONCLUSIONS: The present investigation was the first to identify injury rates and identify specific factors increasing injury risk during ENG training. The identified risk factors provide a basis for recommending future prevention strategies.

A prospective investigation of injury incidence and injury risk factors among Army recruits in military police training.

BACKGROUND: United States Army military police (MP) training is a 19-week course designed to introduce new recruits to basic soldiering skills, Army values and lifestyle, and law enforcement skills and knowledge. The present investigation examined injury rates and injury risk factors in MP training. METHODS: At the start of training, 1,838 male and 553 female MP recruits were administered a questionnaire containing items on date of birth, height, weight, tobacco use, prior physical activity, injury history, and menstrual history. Injuries during training were obtained from electronic medical records and the training units provided data on student graduation and attrition. RESULTS: Successfully graduating from the course were 94.3% of the men and 83.7% of the women. Experiencing at least one injury during training were 34.2% of the men and 66.7% of the women (risk ratio (women/men) = 1.95, 95% confidence interval = 1.79-2.13). Recruits were at higher injury risk if they reported that they were older, had smoked in the past, or had performed less frequent exercise or sports prior to MP training. Men were at higher injury risk if they reported a prior injury and women were at higher risk if they reported missing at least six menstrual cycles in the last year or had previously been pregnant. CONCLUSION: The present investigation was the first to identify injury rates and identify specific factors increasing injury risk during MP training.

Risk factors for medical discharge from United States Army Basic Combat Training.

Past studies indicated that overall Basic Combat Training (BCT) attrition (discharge) was associated with various risk factors. BCT has changed considerably since many of these studies were conducted. This study examined Soldiers medically attrited from BCT. Potential attrition risk factor data on recruits (n = 4,005) were collected from medical records, BCT unit records, and questionnaires. Attrition data from Fort Jackson, South Carolina, showed 203 medical discharges. Cox regression (univariate and multivariate) obtained hazard ratios and 95% confidence intervals for attrition risk factors. Higher attrition risk was associated with female gender. Higher attrition risk for men was associated with cigarette smoking, injury during BCT, and less exercise before BCT. Higher attrition risk for both genders was associated with failure on the initial 2-mile run test and separated or divorced marital status. Attrition risk factors found in this study were similar to those previously identified despite changes in BCT.

Risk factors for injuries in the U.S. Army Ordnance School.

OBJECTIVE: To investigate risk factors for time-loss injuries among soldiers attending U.S. Army Ordnance School Advanced Individual Training. METHODS: Injuries were obtained from an injury surveillance system. A health questionnaire provided data on age, race, rank, current self-reported injury and illness, and tobacco use. Fitness data was obtained from operations office. RESULTS: Cumulative time-loss injury incidence was 31% for men and 54% for women. For men, higher risk of injury was associated with race, a current self-reported injury, smoking before entering the Army, lower sit-up performance, and slower 2-mile run times. For women, higher risk of injury was associated with race, a current self-reported injury, and slower 2-mile run times. CONCLUSION: Smoking cessation and fitness training before entry are potential strategies to reduce injuries among soldiers in the Ordnance School.

Tobacco use prevalence and factors associated with tobacco use in new U.S. Army personnel.

This study examined the prevalence of tobacco use and factors associated with pre-military service cigarette and smokeless tobacco use. From January 2000 to December 2006, military students arriving for Advanced Individual Training at the U.S. Army Ordnance School completed a questionnaire that asked about their use of tobacco products. The prevalence of smokeless tobacco use from 2000 to 2006 for women generally decreased, as did the number of cigarettes smoked per day by men. For men and women, factors associated with cigarette use included younger age, Caucasian race, and use of smokeless tobacco. Factors associated with smokeless tobacco use among men included younger age, Caucasian race, and cigarette use. For women, cigarette use was the only factor associated with smokeless tobacco use. The identified factors in this study could be used to establish strategies in the future to reduce tobacco use in the military.

Injury reduction effectiveness of assigning running shoes based on plantar shape in Marine Corps basic training.

BACKGROUND: Shoe manufacturers market motion control, stability, and cushioned shoes for plantar shapes defined as low, normal, and high, respectively. This assignment procedure is presumed to reduce injuries by compensating for differences in running mechanics. HYPOTHESIS: Assigning running shoes based on plantar shape will not reduce injury risk in Marine Corps basic training. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: After foot examinations, Marine Corps recruits in an experimental group (E: 408 men, 314 women) were provided motion control, stability, or cushioned shoes for plantar shapes indicative of low, medium, or high arches, respectively. A control group (C: 432 men, 257 women) received a stability shoe regardless of plantar shape. Injuries during the 12 weeks of training were determined from outpatient visits obtained from the Defense Medical Surveillance System. Other known injury risk factors (eg, fitness, smoking, prior physical activity) were obtained from a questionnaire, existing databases, or the training units. RESULTS: Cox regression indicated little difference in injury risk between the E and C groups among men (hazard ratio [E/C] = 1.01; 95% confidence interval, 0.82-1.24) or women (hazard ratio [E/C] = 0.88; 95% confidence interval, 0.70-1.10). CONCLUSION: This prospective study demonstrated that assigning shoes based on the shape of the plantar foot surface had little influence on injuries even after considering other injury risk factors.

Effect on injuries of assigning shoes based on foot shape in air force basic training.

BACKGROUND: This study examined whether assigning running shoes based on the shape of the bottom of the foot (plantar surface) influenced injury risk in Air Force Basic Military Training (BMT) and examined risk factors for injury in BMT. METHODS: Data were collected from BMT recruits during 2007; analysis took place during 2008. After foot examinations, recruits were randomly consigned to either an experimental group (E, n=1042 men, 375 women) or a control group (C, n=913 men, 346 women). Experimental group recruits were assigned motion control, stability, or cushioned shoes for plantar shapes indicative of low, medium, or high arches, respectively. Control group recruits received a stability shoe regardless of plantar shape. Injuries during BMT were determined from outpatient visits provided from the Defense Medical Surveillance System. Other injury risk factors (fitness, smoking, physical activity, prior injury, menstrual history, and demographics) were obtained from a questionnaire, existing databases, or BMT units. RESULTS: Multivariate Cox regression controlling for other risk factors showed little difference in injury risk between the groups among men (hazard ratio [E/C]=1.11, 95% CI=0.89-1.38) or women (hazard ratio [E/C]=1.20, 95% CI= 0.90-1.60). Independent injury risk factors among both men and women included low aerobic fitness and cigarette smoking. CONCLUSIONS: This prospective study demonstrated that assigning running shoes based on the shape of the plantar surface had little influence on injury risk in BMT even after controlling for other injury risk factors.

Injury reduction effectiveness of selecting running shoes based on plantar shape.

Popular running magazines and running shoe companies suggest that imprints of the bottom of the feet (plantar shape) can be used as an indication of the height of the medial longitudinal foot arch and that this can be used to select individually appropriate types of running shoes. This study examined whether or not this selection technique influenced injury risk during United States Army Basic Combat Training (BCT). After foot examinations, BCT recruits in an experimental group (E: n = 1,079 men and 451 women) selected motion control, stability, or cushioned shoes for plantar shapes judged to represent low, medium, or high foot arches, respectively. A control group (C: n = 1,068 men and 464 women) received a stability shoe regardless of plantar shape. Injuries during BCT were determined from outpatient medical records. Other previously known injury risk factors (e.g., age, fitness, and smoking) were obtained from a questionnaire and existing databases. Multivariate Cox regression controlling for other injury risk factors showed little difference in injury risk between the E and C groups among men (risk ratio (E/C) = 1.01; 95% confidence interval = 0.88-1.16; p = 0.87) or women (risk ratio (E/C) = 1.07; 95% confidence interval = 0.91-1.25; p = 0.44). In practical application, this prospective study demonstrated that selecting shoes based on plantar shape had little influence on injury risk in BCT. Thus, if the goal is injury prevention, this selection technique is not necessary in BCT.

Injuries and injury risk factors among members of the United States Army Band.

BACKGROUND: This project documented injuries in the professional musical performers of the US Army Band and used a multivariate approach to determine injury risk factors. METHODS: Injuries were obtained from a medical surveillance database. Administrative records from the Band provided fitness test scores, physical characteristics, performing unit (Blues, Ceremonial, Chorale, Chorus, Concert, Strings), and functional group (strings, winds, keyboard, vocal, percussion, brass). A questionnaire completed by 95% of the Band (n=205) included queries on practice time, physical activity, tobacco use, and medical care. RESULTS: One or more injuries were diagnosed in 44 and 53% of Band members in the years 2004 and 2005, respectively. In univariate analysis, higher injury risk was associated with higher body mass index (BMI), less physical activity, prior injury, unit, functional group, and practice duration. In multivariate analysis, less self-rated physical activity, a prior injury, and functional group were independent risk factors. CONCLUSION: In the US Army Band, about half the performers had a medical visit for an injury in a 1-year period and injury risk was associated with identifiable factors.