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Biomedical subjects

J J Knapik

Publications and source records attributed to J J Knapik.

At least 19 recordsLinked to original sources
PubMed2006

Ambulatory physical activity during United States Army basic combat training.

Electronic pedometers were used to quantify locomotor physical activity during an entire 9-week United States Army Basic Combat Training (BCT) cycle. Pedometers were worn on the hips of 4 trainees in each of 10 BCT companies during all BCT activities. Investigators obtained pedometer readings (steps) on a daily basis, and estimated travel distances were obtained by multiplying steps by the average individual step length. A short questionnaire was administered daily to assure trainees wore the pedometers and trained with their companies all day. Trainees performed an average +/- SD of 16 311 +/- 5826 steps/day and traveled an estimated 11.7 +/- 4.4 kilometers/day. The highest daily locomotor activity was during the field training exercise in which trainees took an average +/- SD of 22 372 +/- 12 517 steps/day traveling an estimated 16.2 +/- 9.7 kilometers/day. Differences among the 10 companies ranged from 14 720 +/- 6649 steps/day to 18 729 +/- 6328 steps/day. This survey provided the first examination of locomotor physical activity during an entire BCT cycle.

Adult↗
PubMed2004

Influence of an injury reduction program on injury and fitness outcomes among soldiers.

OBJECTIVE: This study evaluated the influence of a multiple injury control intervention on injury and physical fitness outcomes among soldiers attending United States Army Ordnance School Advanced Individual Training. METHODS: The study design was quasiexperimental involving a historical control group (n = 2559) that was compared to a multiple intervention group (n = 1283). Interventions in the multiple intervention group included modified physical training, injury education, and a unit based injury surveillance system (UBISS). The management responsible for training independently formed an Injury Control Advisory Committee that examined surveillance reports from the UBISS and recommended changes to training. On arrival at school, individual soldiers completed a demographics and lifestyle questionnaire and took an army physical fitness test (APFT: push-ups, sit-ups, and two mile run). Injuries among soldiers were tracked by a clinic based injury surveillance system that was separate from the UBISS. Soldiers completed a final APFT eight weeks after arrival at school. RESULTS: Cox regression (survival analysis) was used to examine differences in time to the first injury while controlling for group differences in demographics, lifestyle characteristics, and physical fitness. The adjusted relative risk of a time loss injury was 1.5 (95% confidence interval 1.2 to 1.8) times higher in the historical control men and 1.8 (95% confidence interval 1.1 to 2.8) times higher in the historical control women compared with the multiple intervention men and women, respectively. After correcting for the lower initial fitness of the multiple intervention group, there were no significant differences between the multiple intervention and historical control groups in terms of improvements in push-ups, sit-ups, or two mile run performance. CONCLUSIONS: This multiple intervention program contributed to a reduction in injuries while improvements in physical fitness were similar to a traditional physical training program previously used at the school.

Adolescent↗
PubMed2003

Injury and fitness outcomes during implementation of physical readiness training.

This study examined injury and physical fitness outcomes in Basic Combat Training (BCT) during implementation of Physical Readiness Training (PRT). PRT is the U.S. Army's emerging physical fitness training program. An experimental group (EG, n = 1284), which implemented the PRT program, was compared to a control group (CG, n = 1296), which used a traditional BCT physical training program during the 9-week BCT cycle. Injury cases were obtained from recruit medical records and physical fitness was measured using the U.S. Army Physical Fitness Test (APFT, consisting of push-ups, sit-ups and a two-mile run). Injury rates were examined using Cox regression after controlled for initial group differences in demographics, fitness and other variables. Compared to the EG, the adjusted relative risk of a time-loss overuse injury in the CG was 1.5 (95 % confidence interval [CI] = 1.0 - 2.1, p < 0.01) for men and 1.4 (95 %CI = 1.1 - 1.8, p < 0.01) for women. There were no differences between groups for traumatic injuries. On the first administration of the final APFT, the EG had a greater proportion of recruits passing the test than the CG (men: 85 % vs. 81 %, p = 0.04; women: 80 % vs. 70 %, p < 0.01). After all APFT retakes, the EG had significantly fewer APFT failures than the CG among the women (1.6 % vs. 4.6 %, p < 0.01) but not the men (1.6 % vs. 2.8 %, p = 0.18); the gender-combined EG had a higher pass rate (1.6 % vs. 3.7 %, p < 0.01). Overall, the PRT program reduced overuse injuries and allowed a higher success rate on the APFT.

Adult↗
PubMed2001

Predictors of low physical fitness in a cohort of active-duty U.S. Air Force members.

BACKGROUND: Each branch of the U.S. armed forces has standards for physical fitness as well as programs for ensuring compliance with these standards. In the U.S. Air Force (USAF), physical fitness is assessed using submaximal cycle ergometry to estimate maximal oxygen uptake (VO2(max)). The purpose of this study was to identify the independent effects of demographic and behavioral factors on risk of failure to meet USAF fitness standards (hereafter called low fitness). METHODS: A retrospective cohort study (N=38,837) was conducted using self-reported health risk assessment data and cycle ergometry data from active-duty Air Force (ADAF) members. Poisson regression techniques were used to estimate the associations between the factors studied and low fitness. RESULTS: The factors studied had different effects depending on whether members passed or failed fitness testing in the previous year. All predictors had weaker effects among those with previous failure. Among those with a previous pass, demographic groups at increased risk were toward the upper end of the ADAF age distribution, senior enlisted men, and blacks. Overweight/obesity was the behavioral factor with the largest effect among men, with aerobic exercise frequency ranked second; among women, the order of these two factors was reversed. Cigarette smoking only had an adverse effect among men. For a hypothetical ADAF man who was sedentary, obese, and smoked, the results suggested that aggressive behavioral risk factor modification would produce a 77% relative decrease in risk of low fitness. CONCLUSIONS: Among ADAF members, both demographic and behavioral factors play important roles in physical fitness. Behavioral risk factors are prevalent and potentially modifiable. These data suggest that, depending on a member's risk factor profile, behavioral risk factor modification may produce impressive reductions in risk of low fitness among ADAF personnel.

Adolescent↗
PubMed2001

The fitness training unit in U.S. Army basic combat training: physical fitness, training outcomes, and injuries.

This study involved a retrospective examination of physical fitness, training outcomes, and injury rates among personnel in the Fitness Training Unit (FTU). Personnel were assigned to the FTU based on low performance on push-ups, sit-ups, and/or a 1-mile run (N = 44 men, 95 women) and received an augmented physical fitness program before basic combat training (BCT). They were compared with 712 men and 379 women who took the same test but were not assigned to the FTU and went directly to BCT. FTU and non-FTU personnel trained in the same battalions. Army Physical Fitness Test scores and BCT outcomes (discharged or completed BCT in 8 weeks) were obtained from unit training records. Injuries during BCT were documented from a review of the medical records. On entry to BCT, FTU women had similar 2-mile run times compared with non-FTU women (21.6 vs. 21.5 minutes, respectively; p = 0.86); FTU men were considerably slower on the 2-mile run than non-FTU men (20.3 vs. 17.3 minutes; p < 0.01). FTU women and non-FTU women had similar graduation success (60% vs. 68%, respectively; p = 0.14) and time-loss injury rates (1.3 vs. 1.4 people injured/100 person-days, respectively; p = 0.90). FTU men were less likely to graduate than non-FTU men (55% vs. 82%; p < 0.01) and more likely to suffer a time-loss injury (1.2 vs. 0.7 people injured/100 person-days; p < 0.01). Efforts should be directed toward providing a sufficient training stimulus to improve the aerobic fitness level of men (as well as women) in the FTU.

Analysis of Variance↗
PubMed2001

Risk factors for training-related injuries among men and women in basic combat training.

PURPOSE: Past investigations indicate that training-related injuries are associated with certain performance-oriented measures of physical fitness and certain lifestyle characteristics. This study examined associations between injuries, direct (physiological) measures of physical fitness, and lifestyle characteristics. METHODS: Subjects were 756 men and 474 women performing the standardized activities involved in U.S. Army Basic Combat Training (BCT). Before BCT, a subsample of subjects (182 men and 168 women) were administered a series of tests that included a treadmill running test (peak VO2), dual-energy x-ray absorptiometry (for body composition), several measures of muscle strength, a hamstring flexibility test, and a vertical jump. A questionnaire addressed smoking habits and prior physical activity. All subjects were administered the Army Physical Fitness test consisting of push-ups, sit-ups, and a 3.2-km run. Gender, age, stature, and body mass were obtained from physical examination records. Injuries incurred during BCT were transcribed from medical records; for each medical visit, the diagnosis, anatomical location, disposition (final outcome of visit), and days of limited duty were recorded. RESULTS: Women had over twice the injury rate of men. For men and women, fewer push-ups, slower 3.2-km run times, lower peak VO2, and cigarette smoking were risk factors for time-loss injury. Among the men only, lower levels of physical activity before BCT and both high and low levels of flexibility were also time-loss injury risk factors. Multivariate analysis revealed that lower peak VO2 and cigarette smoking were independent risk factors for time-loss injury. CONCLUSIONS: Lower aerobic capacity and cigarette smoking were independently associated with a higher likelihood of injury in both men and women during a standardized program of physical training. Further studies are needed to assess associations between injury and body composition and muscular strength.

Adolescent↗
PubMed2001

Angiotensin-converting enzyme genotype and physical performance during US Army basic training.

Prior studies have suggested that angiotensin I-converting enzyme (ACE) genotype correlates with superior physical performance in highly selected populations. This study assessed whether such an association exists in a heterogeneous population. Using polymerase chain reaction techniques, we determined the ACE genotypes (insertion/insertion, deletion/insertion, or deletion/deletion) of 62 male and 85 female US Army recruits. Before and after 8 wk of basic training, we determined peak oxygen uptake and performance on the Army Physical Fitness Test (APFT), which includes standardized measures of muscular endurance (sit-ups, push-ups) and a 2-mile run. Subjects of different ACE genotypes had similar peak oxygen uptakes and APFT scores, both before and after training. Subjects with genotype II had higher APFT scores than others, but the differences were not statistically significant. Furthermore, no ACE genotype group had a performance advantage in analyses that adjusted for baseline fitness. We conclude that ACE genotype does not have a strong effect on aerobic power or muscular endurance in healthy, young American adults drawn from an ethnically and geographically diverse population.

Adult↗
PubMed2001

The prevalence of exercise-induced bronchospasm among US Army recruits and its effects on physical performance.

STUDY OBJECTIVES: To measure the prevalence of exercise-induced bronchospasm (EIB) and to determine its effect on the physical performance response to training in otherwise healthy young adults. DESIGN: Observational, retrospective study. SETTING: Fort Jackson, SC, May to July 1998. PARTICIPANTS: One hundred thirty-seven ethnically diverse US Army recruits undergoing an 8-week Army basic training course. MEASUREMENTS AND RESULTS: Subjects underwent exercise challenge testing at the end of basic training to evaluate for EIB (defined as a decrease in FEV(1) of > or = 15%, 1 or 10 min after running to peak oxygen uptake on a treadmill). Those subjects who were unable to run to peak oxygen uptake, or who were unable to perform two baseline FEV(1) maneuvers the results of which were within 5% of each other, were excluded from analysis. We measured peak oxygen uptake on a treadmill and the scores achieved on the components of the US Army physical fitness test (APFT). Of 137 subjects, 121 (58 men and 63 women) met our inclusion criteria. Eight subjects (7%) had EIB. Subjects who experienced EIB and unaffected control subjects both showed statistically significant gains in performance on the APFT events during basic training. At the end of basic training, peak oxygen uptake levels and APFT event scores were not significantly different between subjects with EIB and unaffected control subjects. CONCLUSIONS: Seven percent of the US Army recruits who were tested had EIB, but this did not hinder their physical performance gains during basic training. EIB per se should not be an absolute reason to exclude individuals from employment in jobs with heavy physical demands.

Adult↗
PubMed2001

Hyponatremia associated with overhydration in U.S. Army trainees.

This report describes a series of hyponatremia hospitalizations associated with heat-related injuries and apparent over-hydration. Data from the U.S. Army Inpatient Data System were used to identify all hospitalizations for hyposmolality/hyponatremia from 1996 and 1997. Admissions were considered as probable cases of overhydration hyponatremia if this was the only, or primary, diagnosis or if it was associated with any heat-related diagnosis. Seventeen medical records were identified, and the events leading to hospitalization were analyzed. The average serum sodium level was 122 +/- 5 mmol/L (range, 115-130 mmol/L). All 17 patients were soldiers attending training schools. Seventy-seven percent of hyponatremia cases occurred in the first 4 weeks of training. Nine patients had water intake rates equal to or exceeding 2 quarts per hour. Most patients were in good health before developing hyponatremia. The most common symptoms were mental status changes (88%), emesis (65%), nausea (53%), and seizures (31%). In 5 of 6 cases in which extensive history was known, soldiers drank excess amounts of water before developing symptoms and as part of field treatment. The authors conclude that hyponatremia resulted from too aggressive fluid replacement practices for soldiers in training status. The fluid replacement policy was revised with consideration given to both climatic heat stress and physical activity levels. Field medical policy should recognize the possibility of overhydration. Specific evacuation criteria should be established for exertional illness.

Fatal Outcome↗
PubMed2001

Discharges during U.S. Army basic training: injury rates and risk factors.

This study examined injury rates and risk factors for discharge in a cohort of 756 men and 474 women in U.S. Army basic combat training (BCT) at Fort Jackson, South Carolina. Investigators systematically screened trainee medical records for injuries and collected medical recommendations to temporarily remove a trainee from BCT to allow recovery from an injury. The BCT unit provided Army Physical Fitness Test (APFT) scores and trainee demographic data. Discharges were identified by reviewing discharge packets and were confirmed through rosters from the BCT units. There were 102 men and 108 women discharged. Person-time injury incidence rates (for time-loss injuries) among discharged and nondischarged men were 1.87 and 0.45 cases/100 person-days, respectively (p < 0.01); the rates for discharged and nondischarged women were 1.95 and 1.01 cases/100 person-days, respectively (p < 0.01). Men had a higher risk of discharge if they had a time-loss injury (p < 0.01), but women did not (p = 0.28). Other discharge risk factors for both men and women included a medical recommendation for removal from training to recover from an injury, lower performance on any of the three APFT events, and lower educational level. Women with more body mass or a higher body mass index also had a marginally higher risk of discharge.

Female↗
PubMed2001

The physical training and rehabilitation program: duration of rehabilitation and final outcome of injuries in basic combat training.

During calendar year 1998, 6% (N = 2,010: men [m] = 670, 3%, women [w] = 1,340, 12%) of soldiers in basic combat training at Fort Jackson, South Carolina (N = 32,251), were unable to continue training as a result of a training-related injury. These soldiers were recommended for the Physical Training and Rehabilitation Program (PTRP) for recovery and rehabilitation. Forty-two percent of recommended soldiers were discharged from the Army rather than assigned to PTRP. The 1,164 (m = 356, w = 808) soldiers assigned to PTRP sustained 1,673 injuries (m = 444, w = 1229). Eighty-three percent of the injuries in PTRP were in the overuse (44%) and stress fracture (39%) categories. Of the 1,164 soldiers assigned to PTRP, 52% (m = 214, w = 386) returned to training. The average (+/- SD) length of stay in PTRP for soldiers returning to duty was 62 +/- 42 days (m = 57 +/- 39, w = 65 +/- 43). Rehabilitation challenges and significant motivational issues presumably contributed to the 52% return to duty incidence for PTRP soldiers.

Adult↗
PubMed2000

Cigarette smoking and exercise-related injuries among young men and women.

BACKGROUND: We evaluate whether a recent history of cigarette smoking is a risk factor for exercise-related injuries sustained during Army basic training, controlling for factors such as demographic, physical fitness, and health variables. METHODS: We conducted an observational cohort study in 1087 male and 915 female Army recruits undergoing 8-week basic military training. Data were collected from questionnaires, anthropometric measurements, physical fitness tests, company training logs, and medical records of all clinic visits. RESULTS: During the 8-week training period, 33% of men and 50% of women had at least one clinic visit for injury, including 14% of men and 25% of women who lost more than 5 days of training due to injury. Recruits who reported smoking at least one cigarette in the month prior to beginning basic training (which was conducted in a smoke-free environment) had significantly higher injury rates during training than those who did not report smoking (40% versus 29% for men, and 56% versus 46% for women). The relationship with smoking history was present most strongly for overuse injuries (32% versus 24% in men and 51% versus 40% in women). Multiple logistic regression analyses controlling for all other factors consistently showed adjusted odds ratios of about 1.5 for injury rate in those with a history of smoking compared to those without. CONCLUSIONS: The association of history of cigarette smoking with injury occurrence was consistent throughout the analyses, with very little confounding by other factors. The detrimental effects of smoking on injuries appears to persist at least several weeks after cessation of smoking.

Adolescent↗
PubMed2000

Effect of rest from running on overuse injuries in army basic training.

BACKGROUND: It has been hypothesized that a period of rest from running in the early weeks of basic military training will prevent stress fractures among recruits. DESIGN: Modification of running schedules in companies of Army recruits undergoing basic military training was assigned. SETTING/PARTICIPANTS: Six male training companies were enrolled and followed during their 8 weeks of basic military training at Fort Bliss, Texas, in summer/fall 1989. INTERVENTION: Intervention companies were asked to rest from running during the second, third, or fourth week of basic military training. MAIN OUTCOME MEASURES: Data were collected from questionnaires, anthropometric measurements, Army physical fitness tests, company training logs, and medical record abstraction of all clinic visits. RESULTS: Among the 1357 enrolled male recruits, there were 236 (17%) with overuse injury and 144 (11%) with traumatic injury, resulting in 535 clinic visits and 1927 training days lost. Stress fracture/reaction rates varied from 3 to 8 per 100 recruits among the intervention companies and 2 to 7 per 100 recruits among the non-intervention companies. Total injury rates were 18 to 35 per 100 recruits in the intervention companies and 18 to 29 per 100 recruits in the non-intervention companies. CONCLUSIONS: The study provided no evidence for a protective effect on overuse injuries of resting from running for 1 week early in basic military training. There was varied physical training among the companies, however, with variation of injury rates that likely related to factors other than the intervention.

Adolescent↗
PubMed2000

Standard and alternative methods of stretcher carriage: performance, human factors, and cardiorespiratory responses.

Transporting a casualty on a stretcher is a common task for medical and military personnel. Stretchers are usually carried by hand, but distributing the load to other parts of the body may have advantages. To examine alternative carriage methods, 11 soldiers walked on a treadmill at 4.8 km/h while performing two-person carries of a stretcher containing an 80-kg manikin. In separate trials, soldiers carried the stretcher using: (1) hand carriage, (2) shoulder straps, (3) a specially designed harness that allowed load shifting between the hips and shoulders (hip-shoulder system), and (4) a clip that fitted on the belt of standard military load carrying equipment (LCE) and placed the stretcher mass mainly on the hips. With each system, subjects walked until volitional fatigue or 30 min. While walking, expired gases and heart rates were obtained and subjects rated their perceived exertion (Borg Scale). At the conclusion of all four trials, subjects rated each system on a number of subjective measures. Results showed that average (+/- SD) carriage times were 2.7+/-1.4, 14.5+/-8.3, 25.4+/-8.1, and 21.7+/-9.9 min with the hand, shoulder, hip-shoulder and LCE systems respectively (p<0.01). Hand carriage resulted in considerably more cardiorespiratory stress (higher heart rate and minute ventilation, p<0.05) than the other three systems, but there were few consistent differences among the other three systems. Perceived exertion in the upper body was less with the hip-shoulder and LCE systems than with the other two systems (p<0.05). Subjects preferred the hip-shoulder and LCE systems overall and for specific subjective characteristics such as comfort, ease of use and stability (p<0.01). These data indicate that moving the stretcher load from the hands and placing that load on the shoulders and/or hips results in improved performance, reduced cardiorespiratory stress and favourable subjective evaluations. Further developmental work should focus on the hip-shoulder and LCE systems.

Adult↗
PubMed2000

Injuries during Marine Corps officer basic training.

On average, about 25% of male and 50% of female enlisted recruits sustain one or more injuries during basic training. Because data on military officer populations are sparse, this study investigated injury incidence, injury rates, and modified duty days that occurred during Marine Corps officer basic training (6 weeks in length). Subjects were 480 officer candidates (including 30 females) undergoing training at Quantico, Virginia. The cumulative injury incidence (one or more injuries) was 60.8%, and the injury rate was 3.9 per 1,000 candidate hours of training. There were 378 primary injury encounters (first visit for a specific injury). The highest injury rates occurred during weeks 2, 3, and 6. Male injury categories with the highest rates (injuries per 100 trainees per 1,000 training hours) were blisters (0.68), sprains (0.58), and bone stress reactions (0.40). The highest injury rates in females were for bone stress reactions (1.35). On average, a total of 3.1% of training days constituted modified duty for each candidate. This study provides basic descriptive injury data for this unique military population that can assist in future planning for injury management and preventive interventional strategies.

Absenteeism↗
PubMed2000

Injuries and injury risk factors among men and women in U.S. Army Combat Medic Advanced individual training.

No previous reports have evaluated injuries or injury risk factors during the advanced individual training (AIT) that follows the Army's initial or basic combat training (BCT). This study examined injuries and injury risk factors among 439 men and 287 women participating in combat medic AIT. A questionnaire addressing demographic and lifestyle characteristics (age, race, tobacco and alcohol use, physical activity, etc.) was administered to all subjects. Stature and body mass were obtained from battalion records. Injuries occurring during both BCT and AIT were transcribed from subject medical records. Results indicated that cumulative injury incidence (subjects with one or more injuries) in BCT was 26% for men and 52% for women (p < 0.01), in consonance with previous investigations. In AIT, injury incidence was 24% for men and 30% for women (p = 0.08). In both BCT and AIT, overuse injuries and lower body injuries accounted for the largest proportions of injuries by diagnosis and anatomical location. Logistic regression revealed that older age (> 25 years), split option (a break in service between BCT and AIT), and higher body mass were independent risk factors for AIT injuries among women. None of the examined variables were independent risk factors for AIT injuries among men.

Adult↗
PubMed1999

Injuries and risk factors in a 100-mile (161-km) infantry road march.

BACKGROUND: Light infantry soldiers (N = 218) completed a 161-km cross-country march over 5 days carrying an average +/- SD load mass (i.e., the weight of all equipment and clothing) of 47 +/- 5 kg. METHODS: Prior to the march, height, weight, body fat, and physical fitness (3.2-km run, sit-ups, push-ups) were measured. Soldiers completed a demographic questionnaire which included questions on age and tobacco use history. RESULTS: Thirty-six percent (78/218) of the soldiers suffered one or more injuries. Of the total injuries, 48% presented were blisters and 18% were foot pain (not otherwise specified). Eight percent (17/218) of the soldiers were unable to complete the march because of injuries. Thirty-five percent (27/78) of the injured soldiers had 1 or more limited duty days for a total of 69 days. Risk of injury was higher among smokers (risk ratio = 1.8, P = 0.03 compared to nonsmokers) and lower among older soldiers (risk ratio = 3.2, P = 0.02, < 20 years compared to > 24 years). CONCLUSIONS: Carrying heavy loads over long distances can result in a high injury incidence to the lower body, since 36% of soldiers were injured during the 161-km march. Smoking and younger age (< 20 years) were independent risk factors for injuries.

Adult↗