Associations between clinically diagnosed medical conditions and dietary supplement use: the US military dietary supplement use study.

OBJECTIVE: This study examined associations between multiple dietary supplement (DS) categories and medical conditions diagnosed by health professionals. DESIGN: Cross-sectional. SETTING: Volunteers completed an online questionnaire on DS use and demographic/lifestyle factors. Medical diagnoses were obtained from a comprehensive military electronic medical surveillance system and grouped into twenty-four clinically diagnosed medical conditions (CDMC). PARTICIPANTS: A stratified random sample of US service members (SM) from all military services (n 26 680). RESULTS: After adjustment for demographic/lifestyle factors (logistic regression), higher risk was found for 92 % (22/24) of CDMC among individual vitamins/minerals users, 58 % (14/24) of CDMC among herbal users, 50 % (12/24) of CDMC among any DS users and 46 % (11/24) of CDMC among multivitamins/multiminerals (MVM) users. Among protein/amino acid (AA) users, risk was lower in 25 % (6/24) of CDMC. For combination products, risk was higher in 13 % (3/24) of CDMC and lower in 8 % (2/24). The greater the number of CDMC, the higher the prevalence of DS use in most DS categories except proteins/AA where prevalence decreased. CONCLUSIONS: Users in many DS categories had a greater number of CDMC, but protein/AA users had fewer CDMC; results for combination products were mixed. These data indicate those with certain CDMC were also users in some DS categories, especially individual vitamins/minerals, herbals and MVM. Data are consistent with the perception that use of DS enhances health, especially in those with CDMC. Protein/AA and combination product users were more likely to be younger, more physically active men, factors that likely reduced CDMC.

Short sleep duration is associated with a wide variety of medical conditions among United States military service members.

OBJECTIVES: This cross-sectional study investigated self-reported sleep duration and its association with a comprehensive range of clinically-diagnosed medical condition categories (CDMCs), as well as the relationship between short sleep duration (≤6 h) and demographic/lifestyle factors, among United States military service members (SMs). METHODS: A stratified random sample of SMs (n = 20,819) completed an online questionnaire on usual daily hours of sleep and demographic/lifestyle characteristics. CDMCs for a six-month period prior to questionnaire completion were obtained from a comprehensive military electronic medical surveillance system and grouped into 33 CDMCs covering both broad and specific medical conditions. Prevalence of CDMCs was compared among three sleep duration categories (≤4, 5-6 and ≥7 h). RESULTS: SMs reported a mean ± standard deviation of 6.3 ± 1.4 h of sleep per day. After adjustment for demographic/lifestyle characteristics, shorter sleep duration was associated with higher odds of a medical condition in 25 of 33 CDMCs, with most (n = 20) demonstrating a dose-response relationship. The five CDMCs with the largest differences between ≤4 vs ≥ 7 h sleep were: diseases of the nervous system (odds ratio [OR] = 2.9, 95% confidence interval [95%CI] = 2.4-3.4), mental/behavioral diseases (OR = 2.7, 95%CI = 2.3-3.2), diseases of the musculoskeletal system (OR = 1.9, 95%CI = 1.6-2.1), diseases of the circulatory system (OR = 1.7, 95%CI = 1.3-2.2), and diseases of the digestive system (OR = 1.6, 95%CI = 1.2-2.0). Six hours of sleep or less was independently associated with older age, less formal education, race, Hispanic ethnicity, higher body mass index, smoking, and military service branch. CONCLUSIONS: In this young, physically active population, reporting shorter sleep duration was associated with a higher risk of multiple CDMCs.

Prescription medication use of United States military service members by therapeutic classification.

Background: This cross-sectional study investigated the prevalence of, and factors associated with, filled prescription medications (FPMs) among United States (US) service members (SMs). Methods: A stratified random sample of active duty SMs from the Air Force, Army, Marine Corps, and Navy was obtained from military workforce records. Participants (n = 26,680) completed a questionnaire on demographics, physical characteristics, and lifestyle factors and approved access to their FPM for the previous 6 months. FPMs were obtained from the military Pharmacy Data Transaction Service that included all prescription medications dispensed at military medical treatment facilities, abroad, at retail pharmacies in the US, and/or through mail-order programs. Results: About two-thirds (65%) of SMs had ≥1 FPM in the 6 months surveillance period. Central nervous system (CNS) agents had the highest prevalence (41%), followed by anti-infective agents (20%), eye/ear/nose/throat preparations (20%), gastrointestinal drugs (18%), autonomic drugs (17%), skin and mucous membrane agents (13%), antihistamine drugs (12%), respiratory tract agents (12%) and cardiovascular drugs (9%). Among CNS agents, overall prevalence of dispensed non-steroidal anti-inflammatory drug (NSAIDs) was 30%. The odds of any FPM was independently associated with female gender, older age, higher body mass index, former tobacco use (smoking and smokeless tobacco), lower alcohol consumption, and was highest among Army, lowest among Marine Corps personnel. Conclusion: In this sample of SMs, dispensing of prescription medication was high, especially NSAIDs, but dispensing of cardiovascular drugs was much lower compared to the general US population, likely because of the younger age and higher level of physical activity of SMs.

Dietary Supplement and Prescription Medication Use Among US Military Service Members With Clinically Diagnosed Medical Conditions: The US Military Dietary Supplement Use Study.

BACKGROUND: Use of prescription medications (PMs) with dietary supplements (DSs) can be hazardous because of potential adverse interactions, but patterns of dual use in military service members (SMs) has not been examined. OBJECTIVE: Investigate dual use of filled PMs (FPMs) and DSs, factors associated with dual use, and dual use among SMs with clinically diagnosed medical conditions (CDMCs). DESIGN: Cross-sectional. Data on FPMs and CDMCs were obtained from medical surveillance records. Between December 2018 and August 2019, participants completed a questionnaire on DS use in the previous 6 months. PARTICIPANTS: A stratified random sample of 26,880 SMs from all military services. MAIN OUTCOME MEASURES: Prevalence of dual use of FPMs with DSs within a 6-month period, demographic/lifestyle factors associated with dual use, and prevalence of dual use among SMs with CDMCs. STATISTICAL ANALYSIS: Prevalences were calculated as percents, χ2 statistics examined differences across various strata of demographic and lifestyle characteristics, and univariable and multivariable logistic regression determined the odds of using FPMs with DSs for various CDMCs. RESULTS: About one-half (49%) of SMs had dual use of FPMs with DSs in the 6-month period. Dual use was higher among women; increased with older age, more formal education, higher body mass index, and more physical activity; was highest among American Indian SMs and lowest among Asian SMs; was higher among former tobacco users; and was highest among Army personnel and lowest among Marine Corps personnel. The overall prevalence of dual use in the 6-month period was higher among those with a CDMC than those without (62% vs 19%), and this relationship was maintained for 20 International Classification of Diseases, Revision 10, code groupings covering virtually all CDMCs. CONCLUSION: This is the first study to document a high prevalence of dual FPMs and DSs in SMs, especially among those with CDMCs.

Prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among active duty United States military personnel.

BACKGROUND: Although representative data on caffeine intake in Americans are available, these data do not include US service members (SMs). The few previous investigations in military personnel largely involve convenience samples. This cross-sectional study examined prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among United States active duty military service members (SMs). METHODS: A stratified random sample of SMs were asked to complete an on-line questionnaire on their personal characteristics and consumption of caffeinated products (exclusive of dietary supplements). Eighteen percent (n = 26,680) of successfully contacted SMs (n = 146,365) completed the questionnaire. RESULTS: Overall, 87% reported consuming caffeinated products ≥1 time/week. Mean ± standard error per-capita consumption (all participants) was 218 ± 2 and 167 ± 3 mg/day for men and women, respectively. Caffeine consumers ingested 243 ± 2 mg/day (251 ± 2 mg/day men, 195 ± 3 mg/day women). On a body-weight basis, men and women consumed respectively similar caffeine amounts (2.93 vs 2.85 mg/day/kg; p = 0.12). Among individual caffeinated products, coffee had the highest use (68%), followed by sodas (42%), teas (29%), energy drinks (29%) and gums/candy/medications (4%). In multivariable logistic regression, characteristics independently associated with caffeine use (≥1 time/week) included female gender, older age, white race/ethnicity, higher body mass index, tobacco use or former use, greater alcohol intake, and higher enlisted or officer rank. CONCLUSION: Compared to National Health and Nutrition Examination Survey data, daily caffeine consumption (mg/day) by SMs was higher, perhaps reflecting higher mental and physical occupational demands on SMs.

Adverse Effects Associated with Multiple Categories of Dietary Supplements: The Military Dietary Supplement Use Study.

BACKGROUND: About 50% of Americans and 70% of US military service members (SMs) regularly use dietary supplements (DSs) and some are associated with adverse effects (AEs). SMs are more likely to use unsafe DSs than civilians. OBJECTIVE: The aim of this investigation was to examine the prevalence of, and factors associated with, AEs. DESIGN: Cross-sectional. PARTICIPANTS: A stratified random sample of 200,000 US SMs from the Air Force, Army, Marine Corps, and Navy were obtained from military workforce records. Eighteen percent (n = 26,681) of successfully contacted SMs (n = 146,365) volunteered to participate between December 2018 and August 2019. Participants completed a detailed online questionnaire on demographic characteristics, lifestyle factors, and AEs associated with DS use. MAIN OUTCOME MEASURE: Prevalence of, and factors associated with, AEs among DS users. STATISTICAL ANALYSIS: Prevalence of AEs was calculated by DS categories. Linear trends, χ2 statistics, and multivariable logistic regression examined associations between AEs and demographic characteristics, lifestyle factors, and number DSs consumed. RESULTS: Proportion of DS users (≥ 1 time /week) reporting ≥1 AE was 18% overall, 20% for combination products (ie, weight loss, muscle building, and before/after workout supplements), 8% for purported prohormones, 6% for protein/amino acid products, 6% for multivitamin/multiminerals, 6% for individual vitamins/minerals, 4% for herbal products, and 2% for joint health products. Combination products are very popular in military personnel with nearly half of SMs regularly taking them. In multivariable analysis, reporting AEs were independently associated with female gender, younger age, higher body mass index, smoking, higher alcohol intake, service in the Army, Navy, or Marine Corps (compared with Air Force), and consumption of a greater number of DSs. CONCLUSIONS: A large proportion of SMs report experiencing AEs, especially users of combination products and purported prohormone supplements. This study presents contemporary data collected from a very large at-risk population on potentially hazardous categories of DSs.

Injuries During High-Intensity Functional Training.

High-intensity functional training (HIFT) involves high-volume and high-intensity physical activities with short rest periods between movements and the use of multiple-joint exercises. This paper analyzes narrative and systematic reviews covering studies of injuries sustained during HIFT. Two narrative and six systematic reviews on injuries during HIFT were identified. Seven reviews concluded that the injury incidences or injury rates during HIFT were similar to those of comparable sports and exercise programs. The most often injured anatomic locations were shoulders, backs, and knees. The most comprehensive and recent review involved 21 retrospective and three prospective studies. In this review, mean ± standard deviation (SD) injury prevalence was 35% ± 15%, the injury rate was approximately 3 ± 5 injuries/1,000 hours of training, and the prevalence of injuries requiring surgery was 6% ± 5%. Most injuries were associated with weightlifting exercises, especially deadlifts, snatches, clean and jerks, and overhead presses. Other risk factors included participation time in HIFT, participation in competition, prior injuries, weekly training frequency, male sex, older age, and alternating training loads. Although most studies included in these reviews were of lower methodologic quality, current evidence suggests that injury rates in HIFT are similar to those of other exercise activities. More high-quality prospective studies are needed to fully evaluate HIFT safety.

Prevalence, factors associated with use, and adverse effects of sport-related nutritional supplements (sport drinks, sport bars, sport gels): the US military dietary supplement use study.

BACKGROUND: Sport-related nutritional supplements (SRNSs) include sport drinks, sport bars, and sport gels. Previous studies indicate that 25-35 % of athletes and 25-50 % of military personnel report using these supplements. This study examined prevalence, factors associated with use, and adverse effects (AEs) of SRNSs among United States military service members (SMs). METHODS: A stratified random sample of 200,000 SMs was obtained from military workforce records, and asked to complete a survey on demographics, SRNS use, and AEs experienced. About 18 % (n = 26,681) of contacted SMs (n = 146,365) completed the survey between December 2018 and August 2019. RESULTS: Overall, 45 % of SMs used ≥ 1 SRNS at least once per week in the past 6 months. Prevalence of use (± standard error) for sport drinks, bars, and gels were 32 ± 0.3, 27 ± 0.3, and 3 ± 0.1 %, respectively. Use of 1, 2, or 3 SRNSs was 28.9 ± 0.5, 13.6 ± 0.6, and 2.2 ± 0.6 %, respectively. Multivariable logistic regression indicated greater use of any SRNS was independently associated with male gender, younger age, single marital status, more weekly aerobic or resistance training, tobacco use, higher alcohol intake, officer status, combat arms occupations, and service in the Marine Corps or Navy (compared to the Air Force). Overall, the proportion of users reporting ≥ 1 AE was 2.0 ± 0.1 %, with 1.3 ± 0.1 % for sport drinks, 1.6 ± 0.2 % for sport bars, and 2.8 ± 0.6 % for sport gels. CONCLUSIONS: This large study of a stratified random sample of SMs found that nearly half of SMs consumed SRNSs weekly, and self-reported AEs were comparatively low. The AE incidence for SRNSs was much lower than typically found for dietary supplements, possibly because of more rigorous regulatory oversight for SRNSs.

Prevalence of and Factors Associated with Dietary Supplement Use in a Stratified, Random Sample of US Military Personnel: The US Military Dietary Supplement Use Study.

BACKGROUND: About 50% of Americans and 70% of US military service members use dietary supplements (DSs). OBJECTIVES: This cross-sectional survey examined current prevalence of and factors associated with DS use in service members. METHODS: A stratified random sample of 200,000 service members from the Air Force, Army, Marine Corps, and Navy was obtained from military manpower records, and these service members were asked to complete a questionnaire on their DS use and personal characteristics. Chi-square statistics and multivariable logistic regression examined differences across various strata of demographic, lifestyle, and military characteristics. RESULTS: About 18% of successfully contacted service members (n = 26,681) completed the questionnaire between December 2018 and August 2019 (mean ± SD age: 33 ± 8 y, 86% male). Overall, 74% reported using ≥1 DS/wk. Multivitamins/multiminerals were the most commonly used DSs (45%), followed by combination products (44%), proteins/amino acids (42%), individual vitamins/minerals (31%), herbals (20%), joint health products (9%), and purported prohormones (5%). In multivariable analysis, factors independently associated with DS use included female gender [OR (female/male): 1.91; 95% CI: 1.73, 2.11], older age [OR (≥40/18-24 y): 1.25; 95% CI: 1.08, 1.44], higher education level [OR (college degree/high school or less): 1.35; 95% CI: 1.19, 1.53], higher BMI [OR (≥30/<25 kg/m2): 1.37; 95% CI: 1.25, 1.52], more weekly resistance training [OR (>300/≤45 min/wk): 5.05; 95% CI: 4.55, 5.61], smokeless tobacco use [OR (user/nonuser): 1.30; 95% CI: 1.17, 1.44], higher alcohol intake [OR (≥72/0 mL/wk): 1.41; 95% CI: 1.29, 1.54], and higher military rank [OR (senior officer/junior enlisted): 1.26; 95% CI: 1.06, 1.51]. CONCLUSIONS: Compared with civilian data from the NHANES, service members were much more likely to use DSs and used different types of DSs, especially combination products and proteins/amino acids often used to purportedly enhance physical performance. Comparisons with previous military data suggest DS use has increased over time.

Clinically diagnosed iron and iodine deficiencies and disorders in the entire population of US military service members from 1997 to 2015.

OBJECTIVE: Iron and/or iodine deficiencies can have multiple serious adverse health outcomes, but examination of incidence rates of these deficiencies has rarely been conducted in any large population. This study examined incidence rates, temporal trends and demographic factors associated with medically diagnosed iron and iodine deficiencies/disorders in US military service members (SM). DESIGN: The Defense Medical Epidemiological Database (DMED) was queried for medical visits of active duty SM to obtain specific International Classification of Diseases, Version 9, codes involving clinically diagnosed iron and iodine deficiencies/disorders. SETTING: Analysis of existing database (DMED). PARTICIPANTS: Entire population of US military SM from 1997 to 2015 (average n per year = 1 382 266, 15 % women). RESULTS: Overall incidence rates for iron and iodine were 104 and 36 cases/100 000 person-years, respectively. Over the 19-year period, rates for iron disorders increased steadily (108 % for men, 177 % for women). Rates for iodine disorders also increased steadily for men (91 %), but, for women, there was an initial rise followed by a later decline. Overall, women's rates were 12 and 10 times higher than men's for iron and iodine, respectively. Compared with whites, blacks and those of other races had higher rates of deficiencies of both minerals. Incidence rates for iodine deficiency increased substantially with age. CONCLUSIONS: The overall incidence of clinically diagnosed iron and iodine deficiency among SM was low, but increased over the 19 years examined, and certain demographic groups were at significantly greater risk. Given the unexpected increases in incidence of these mineral disorders, increased surveillance may be appropriate.Clinical Trial Registration No. ISRCTN58987177 (http//:www.isrctn.com/ISRCTN58987177).

Achilles Tendinopathy: Pathophysiology, Epidemiology, Diagnosis, Treatment, Prevention, and Screening.

Achilles tendinopathy (AT) is a clinical term describing a nonrupture injury of the Achilles tendon where the patient presents with pain, swelling, and reduced performance and symptoms exacerbated by physical activity. About 52% of runners experience AT in their lifetime and in the United States military the rate of clinically diagnosed AT cases was 5/1000 person-yr in 2015. The pathophysiology can be viewed on a continuum proceeding from reactive tendinopathy where tenocytes proliferate, protein production increases, and the tendon thickens; to tendon disrepair in which tenocytes and protein production increase further and there is focal collagen fiber disruption; to degenerative tendinopathy involving cell death, large areas of collagen disorganization, and areas filled with vessels and nerves. Inflammation may be present, especially in the early phases. Some evidence suggests AT pain may be due to neovascularization and the ingrowth of new nerve fibers in association with this process. Prospective studies indicate that risk factors include female sex, black race, higher body mass index, prior tendinopathy or fracture, higher alcohol consumption, lower plantar flexion strength, greater weekly volume of running, more years of running, use of spiked or shock absorbing shoes, training in cold weather, use of oral contraceptives and/ or hormone replacement therapy, reduced or excessive ankle dorsiflexion range of motion, and consumption of antibiotics in the fluoroquinolone class. At least 10 simple clinical tests are available for the diagnosis of AT, but based on accuracy and reproducibility, patient self-reports of morning stiffness and/or pain in the tendon area, pain on palpation of the tendon, and detection of Achilles tendon thickening appear to be the most useful. Both ultrasound and magnetic resonance imaging (MRI) are useful in assisting in diagnosis with MRI providing slightly better sensitivity and specificity. Conservative treatments that have been researched include: (1) nonsteroidal anti-inflammatory medication, (2) eccentric exercise, (3) stretching, (4) orthotics, (5) bracing, (6) glyceryl trinitrate patches, (7) injection therapies (corticosteroids, hyaluronic acid, platelet-rich plasma injections), (8) shock wave therapy, and (9) low-level laser therapy. Nonsteroidal anti-inflammatory medication and corticosteroid injections may provide short-term relief but do not appear effective in the longer term. Eccentric exercise and shock wave therapies are treatments with the highest evidence- based effectiveness. Prevention strategies have not been well researched, but in specific populations balance training (soccer players) and shock-absorbing insoles (military recruits) may be effective. Ultrasound scans might be useful in predicting future AT occurrences.

Diet Quality Is Associated with Physical Performance and Special Forces Selection.

PURPOSE: This study determined associations between diet quality measured by the Healthy Eating Index (HEI)-2015, physical performance, and successful selection following a U.S. Army Special Forces Assessment and Selection course characterized by arduous cognitive and physical demands. METHODS: The HEI-2015 scores were calculated from usual diet assessed with a Block food frequency questionnaire among 782 soldiers attending Special Forces Assessment and Selection. Differences in HEI-2015 scores according to demographics and physical performance were determined with analysis of variance. Differences in likelihood of selection according to HEI-2015 scores were determined with logistic regression. Models were adjusted for potential confounders: age, education, body mass index (BMI), duration and type of resistance training, and smoking. RESULTS: The HEI-2015 total score was higher among older soldiers (≥25 yr), those with more education (≥some college), higher body mass index (≥25), longer duration of resistance training (≥400 min·wk), those that reported use of free weights, suspension training, Olympic lifting, and nonsmokers (P < 0.05). The HEI-2015 total score was higher among those with higher Army Physical Fitness Test (APFT) total scores, APFT sit-up score, APFT run score, and faster loaded road march times (P < 0.05). Those with higher HEI-2015 total scores were 75% (quartile 3 vs quartile 1: odds ratio, 1.75; 95% confidence interval, 1.09-2.81) and 65% (quartile 4 vs quartile 1: odds ratio, 1.65, 95% confidence interval, 1.03-2.65) more likely to be selected. Higher scores for total vegetables, greens and beans, seafood and plant protein, and refined grains, but lower sodium scores (indicating more sodium consumed), were associated with better physical performance (P < 0.05). CONCLUSIONS: Dietary patterns that conform to federal dietary guidelines (except sodium) are associated with physical performance and Special Forces selection.

Functional Movement Screen (FMS™) Scores and Demographics of US Army Pre-Ranger Candidates.

INTRODUCTION: The United States Army Rangers are a unique population whose training requirements are intensive, and physically and mentally demanding. The Functional Movement Screen (FMS) is a movement screening tool designed to assess movement quality and asymmetries in movement with the potential to identify injury risk. This study was a descriptive, cross-sectional investigation examining associations between FMS scores and the various measures of health and performance of active duty soldiers in light infantry units who were involved in the U.S. Army Pre-Ranger Course (PRC). MATERIALS AND METHODS: Before the PRC, 491 male soldiers (mean age = 24.0 ± 3.8 years; mean height = 176.6 ± 7.2 cm; mean body mass = 80.2 ± 9.8 kg) completed a questionnaire which included items on self-assessed physical fitness, last Army physical fitness test (APFT) score, tobacco use, and injury history. The soldiers then completed the FMS, which consisted of seven movements and three clearing tests. From the FMS results, a determination of asymmetries (i.e., differences in FMS scores between the right and left side of the body) was made. Differences between groups were analyzed via an independent sample t-test, a one-way analysis of variance, or a chi-square as appropriate. Significance was set at 0.05 a priori. RESULTS: The average composite FMS score was 16.4 (±1.9) points. Soldiers reporting ≥290 APFT points achieved a higher FMS score than those reporting lower APFT scores (16.5 ± 2.0 vs 16.1 ± 2.0 points, P = 0.03). Soldiers reporting either tobacco use or a previous musculoskeletal injury had lower FMS scores than those not reporting these (tobacco: 16.1 ± 2.1 vs 16.5 ± 1.8 points, P = 0.02; injury: 16.0 ± 2.2 vs 16.6 ± 1.8 points, P < 0.01). FMS asymmetries were not related to APFT scores, tobacco use, or self-rated fitness. As self-rated fitness increased so did APFT scores. CONCLUSIONS: Active duty soldiers of a light infantry division achieved FMS scores similar to other military populations tested, and the composite FMS score was related to higher APFT scores, absence of tobacco use, and absence of previous musculoskeletal injuries. Improving PRC candidate healthy habits through highlighting the negative associations between poorer fitness, cigarette tobacco use and movement quality, may reduce injury risk and increase PRC completion potential.

Epidemiologic Evidence and Possible Mechanisms for the Association Between Cigarette Smoking and Injuries. Part 2: Is the Relationship Between Smoking and Injuries Causal?

Part 1 of this series reviewed the epidemiologic evidence for the association between cigarette smoking and injuries and possible biological and psychosocial mechanisms to account for this relationship. In the present article, nine criteria are explored to determine if smoking is a direct cause of injuries (i.e., a causal relationship). There is substantial evidence that individuals who smoked in the past have a higher subsequent risk of injury. A recent meta-analysis found that smokers in the military were 1.31 times more likely to be injured than nonsmokers and Servicemembers with low, medium, and high levels of smoking had 1.27, 1.37, and 1.71 times, respectively, the risk of injury compared with nonsmokers. The association between smoking and injuries has been reported in at least 18 US military studies and in 14 civilian studies in seven countries. The biological plausibility of the association was discussed extensively in part 1 of this series. A possible alternative explanation with sufficient data was that smokers may be risk takers and it is the risk-taking behavior that increases injury risk (not smoking per se). Once an individual no longer smokes, a decrease in injury risk has been reported for at least bone health and wound healing. The effects of smoking do not appear to be specific to one type of injury, possibly because of the numerous compounds in tobacco smoke that could affect tissues and physiological processes, with evidence provided for bones, tendons, and healing processes. The association was consistent with other knowledge, with some evidence provided from other types of medical problems and trends in smoking and injury-related mortality. In summary, the association between smoking and injuries appears to meet many of the criteria for a causal relationship.

Epidemiological Evidence and Possible Mechanisms for the Association Between Cigarette Smoking and Injuries (Part 1).

Surveys indicated that 24% of military personnel are current cigarette smokers. Smoking is well known to increase the risk of cancers, cardiovascular and respiratory diseases, reproductive problems, and other medical maladies, but one of the little known effects of smoking is that on injuries. There is considerable evidence from a variety of sources that (1) smoking increases overall injury risk, (2) the greater the amount of smoking, the higher is the injury risk, and (3) smoking is an independent injury risk factor. Smoking not only affects the overall injury risk but also impairs healing processes following fractures (e.g., longer healing times, more nonunions, more complications), ligament injury (e.g., lower subjective function scores, greater joint laxity, lower subsequent physical activity, more infections), and wounding (e.g., delayed healing, more complications, less satisfying cosmetic results). Smoking may elicit effects on fractures through low bone mineral density (BMD), lower dietary intake of calcium and vitamin D, altered calcium metabolism, and effects on osteogenesis and sex hormones. Effects on wound healing may be mediated through altered neutrophils and monocytes functions resulting in reduced ability to fight infections and remove damaged tissue, reduced gene expression of cytokines important for tissue healing, and altered fibroblast function leading to lower density and amount of new tissue formation. Limited data suggest smoking cessation has favorable effects on various aspects of bone health over periods of 1 to 30 years. Favorable effects on neutrophil and monocyte functions may occur as early as 4 weeks, but fibroblast function and collagen metabolism (important for wound remodeling) appear to take considerably longer and may be dependent on the amount of prior smoking. Part 2 of this series will use this information to explore the possibility of a causal relationship between smoking and injuries.

Stress Fractures: Etiology, Epidemiology, Diagnosis, Treatment, and Prevention.

Stress fractures are part of a continuum of changes in healthy bones in response to repeated mechanical deformation from physical activity. If the activity produces excessive repetitive stress, osteoclastic processes in the bone may proceed at a faster pace than osteoblastic processes, thus weakening the bone and augmenting susceptibility to stress fractures. Overall stress fracture incidence is about three cases per 1,000 in active duty Servicemembers, but it is much higher among Army basic trainees: 19 per 1,000 for men and 80 per 1,000 for women. Well-documented risk factors include female sex, white ethnicity, older age, taller stature, lower aerobic fitness, prior physical inactivity, greater amounts of current physical training, thinner bones, cigarette smoking, and inadequate intake of vitamin D and/or calcium. Individuals with stress fractures present with focal tenderness and local pain that is aggravated by physical activity and reduced by rest. A sudden increase in the volume of physical activity along with other risk factors is often reported. Simple clinical tests can assist in diagnosis, but more definitive imaging tests will eventually need to be conducted if a stress fracture is suspected. Plain radiographs are recommended as the initial imaging test, but magnetic resonance imaging has higher sensitivity and is more likely to detect the injury sooner. Treatment involves first determining if the stress fracture is of higher or lower risk; these are distinguished by anatomical location and whether the bone is loaded in tension (high risk) or compression (lower risk). Lowerrisk stress fractures can be initially treated by reducing loading on the injured bone through a reduction in activity or by substituting other activities. Higher-risk stress fractures should be referred to an orthopedist. Investigated prevention strategies include modifications to physical training programs, use of shock absorbing insoles, vitamin D and calcium supplementation, modifications of military equipment, and leadership education with injury surveillance.

Caffeine consumption among active duty United States Air Force personnel.

Data from the National Health and Nutrition Examination Survey (NHANES) indicated that 89% of Americans regularly consumed caffeinated products, but these data did not include military personnel. This cross-sectional study examined caffeine consumption prevalence, amount of daily consumption, and factors associated with caffeine intake in active duty United States (US) Air Force personnel. Service members (N = 1787) stationed in the US and overseas completed a detailed questionnaire describing their intake of caffeine-containing products in addition to their demographic, lifestyle, and military characteristics. Overall, 84% reported consuming caffeinated products ≥1 time/week with caffeine consumers ingesting a mean ± standard error of 212 ± 9 mg/day (224 ± 11 mg/day for men, 180 ± 12 mg/day for women). The most commonly consumed caffeinated products (% users) were sodas (56%), coffee (45%), teas (36%), and energy drinks (27%). Multivariate logistic regression modeling indicated that characteristics independently associated with caffeine consumption (≥1 time/week) included older age, ethnicity other than black, tobacco use, less aerobic training, and less sleep; energy drink use was associated with male gender, younger age, tobacco use, and less sleep. Compared to NHANES data, the prevalence of caffeine consumption in Air Force personnel was similar but daily consumption (mg/day) was higher.

Load Carriage-Related Paresthesias (Part 2): Meralgia Paresthetica.

This is the second of a two-part series addressing symptoms, evaluation, and treatment of load carriage- related paresthesias. Part 1 addressed rucksack palsy and digitalgia paresthetica; here, meralgia paresthetica (MP) is discussed. MP is a mononeuropathy involving the lateral femoral cutaneous nerve (LFCN). MP has been reported in load carriage situations where the LFCN was compressed by rucksack hipbelts, pistol belts, parachute harnesses, and body armor. In the US military, the rate of MP is 6.2 cases/10,000 personyears. Military Servicewomen have higher rates than Servicemen, and rates increase with age, longer loadcarriage distance or duration, and higher body mass index. Patients typically present with pain, itching, and paresthesia on the anterolateral aspect of the thigh. There are no motor impairments or muscle weakness, because the LFCN is entirely sensory. Symptoms may be present on standing and/or walking, and may be relieved by adopting other postures. Clinical tests to evaluate MP include the pelvic compression test, the femoral nerve neurodynamic test, and nerve blocks using lidocaine or procaine. In cases where these clinical tests do not confirm the diagnosis, specialized tests might be considered, including somatosensory evoked potentials, sensory nerve conduction studies, high-resolution ultrasound, and magnetic resonance imaging. Treatment should initially be conservative. Options include identifying and removing the compression if it is external, nonsteroidal inflammatory medication, manual therapy, and/or topical treatment with capsaicin cream. Treatments for intractable cases include injection of corticosteroids or local anesthetics, pulsed radiofrequency, electroacupuncture, and surgery. Military medical care providers may see cases of MP, especially if they are involved with units that perform regular operations involving load carriage.

Injuries and injury prevention during foot marching.

Since the beginning of recorded history, Soldiers have carried arms and equipment on their bodies. More recently, loads have substantially increased, driven by improvements in weapons technology and personal protection. As Soldier loads increase, there are increases in energy cost, altered gait mechanics, increased stress on the musculoskeletal system, and more rapid fatigue, factors that may increase the risk of injury. Common injuries and symptoms experienced by Soldiers on load-carriage missions include foot blisters, metatarsalgia, knee problems, and back problems. This article discusses these problems, providing diagnoses, injury mechanisms, and preventive measures. In general, lighter loads, improving load distribution, using appropriate physical training, selecting proper equipment, and using specific prevention techniques will facilitate load carriage and provide Special Operations Forces with a higher probability of mission success.

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.