The gap between the current dyslipidemia guidelines and the physicians' treatment targets in patients with type 2 diabetes in Turkey.

AIM: Lipid-lowering therapy (LLT) is a key factor in the prevention of cardiovascular mortality and morbidity in diabetic patients. Current guidelines have expanded the population of patients with diabetes for whom aggressive low-density lipoprotein cholesterol (LDL-C) lowering therapy should be considered. This study evaluated the management of dyslipidemia in patients with type 2 diabetes in real life. METHODS: Secondary care physicians in a tertiary center recruited 707 patients. The prevalence of statin use along with the achievement of cholesterol targets, predictors for receiving statin, and possible reasons for lack of therapy were investigated. RESULTS: Only 33% of the patients had received statin therapy, and this was significantly higher in those with cardiovascular disease (47% versus 27%; P<0.001). Most of the patients had LDL-C levels of >100 mg/dL (77%), with only 5% having LDL-C levels of <70 mg/dL. Forty-one percent of the patients had never been prescribed LLT previously while 26% had been prescribed this type of therapy in the past but had stopped using it. The most frequent reason for discontinuation of the statin therapy was a physician's advice to stop the medication. The patients taking statins had similar LDL-C levels as those who had never been prescribed statins and those who had discontinued their use of statins on the advice of a physician. CONCLUSION: The majority of diabetic patients are undertreated with statins and minority of them achieve LDL-C target levels. Our findings suggest that there is a large discrepency between evidence-based recommendations and physicians' treatment attitudes.

Increased oxidative DNA damage in lean normoglycemic offspring of type 2 diabetic patients.

OBJECTIVE: Several studies have shown increased oxidative stress in patients with pre-diabetes and newly diagnosed Type 2 diabetes mellitus (T2DM). It has been proposed that oxidative stress initiates insulin resistance in genetically predisposed individuals. The aim of this study was to evaluate the markers of oxidative stress in the offspring of patients with T2DM. MATERIAL AND METHODS: We examined 60 lean normoglycemic offspring of Type 2 diabetics, and 52 age, sex and body mass index matched subjects without family history of T2DM as controls. Anthropometric, biochemical and carotid intima media thickness (IMT) measurements and oral glucose tolerance test (OGTT) were performed. Erythrocyte superoxide dismutase and glutathione peroxidase activities, serum nitric oxide, plasma total sulfhydryl (tSH) groups, plasma total antioxidant status, plasma malondialdehyde and serum 8-hydroxydeoxy-guanosine (8-OHdG) levels were compared between 2 groups. RESULTS: 2 groups were similar for the measurements of anthropometric, blood pressure, lipids, fasting glucose, HOMA-IR and carotid IMT. Glucose levels during OGTT were significantly higher in the offspring of Type 2 diabetics than controls (p=0.035). The offspring of Type 2 diabetics showed a significant increase in serum 8-OHdG level (p=0.005) and plasma tSH groups (p=0.032) when compared to the controls. Significant differences were not obtained in other oxidative stress marker levels between 2 groups. CONCLUSION: Main finding of our study was the presence of increased oxidative DNA damage in lean normoglycemic offspring of Type 2 diabetic patients. There is a need for further clinical studies in order to explain whether oxidative stress is present in genetically predisposed subjects and induces the insulin resistance.

The relation of adiponectin and tumor necrosis factor alpha levels between endothelial nitric oxide synthase, angiotensin-converting enzyme, transforming growth factor beta, and tumor necrosis factor alpha gene polymorphism in adrenal incidentalomas.

OBJECTIVE: The aim of our study was to demonstrate demographic characteristics, presence of inflammatory markers, distribution of angiotensin-converting enzyme (ACE), tumor necrosis factor (TNF), endothelial nitric oxide synthase (eNOS) genotypes and relations among these parameters in these patients and control subjects. RESEARCH DESIGN AND METHODS: Study samples were collected from 50 patients with adrenal mass and 30 control groups. The eNOS, ACE, TNF-alpha, transforming growth factor (TGF)-beta genes polymorphisms, TNF-alpha, adiponectin levels were analysed in 50 unrelated Turkish patients with a diagnosis of adrenal incidentaloma (AI). RESULTS: There was statistically significant difference between TNF-alpha levels of patient and controls (p=0.048). We have not detected the connection between TGF-beta, TNF-alpha, ACE, eNOS gene polymorphism with serum TNF-alpha and adiponectin levels. In this study, we demonstrated that there were significant differences for ACE genotypes in the patients when compared to the controls (p<0.05). The percentages of the ID, DD, II genotypes for ACE gene polymorphism in the patients group were 30.0, 13.0, 7.0%, respectively. CONCLUSIONS: According to different cases of eNOS, TGF-beta, ACE, and TNF-alpha gene genotypes; no statistical significant difference was found between basal cortisol, ACTH, DHEAS, metanephrine, renin, aldosterone, normetanephrine, 17-hydroxyprogesterone, 1 mg low-dose dexamethasone suppression test-cortisol response and AI size. In this study, I/D genotype was determined to be statistically higher in ACE gene in patients with AI (p=0.014).

Injuries in women associated with a periodized strength training and running program.

Forty-five women participated in a 24-week physical training program designed to improve lifting, load carriage, and running performance. Activities included weightlifting, running, backpacking, lift and carry drills, and sprint running. Physicians documented by passive surveillance all training-related injuries. Thirty-two women successfully completed training program. Twenty-two women (48.9%) suffered least 1 injury during training, but only 2 women had to drop out of the study because of injuries. The rate of injury associated with lost training time was 2.8 injuries per 1,000 training hours of exposure. Total clinic visits and days lost from training were 89 and 69, respectively. Most injuries were the overuse type involving the lower back, knees, and feet. Weightlifting accounted for a majority of the lost training days. A combined strength training and running program resulted in significant performance gains in women. Only 2 out of 45 participants left the training program cause of injuries.

Regional body composition changes in women after 6 months of periodized physical training.

Data are lacking regarding regional morphological changes among women after prolonged physical training. This study employed dual-energy X-ray absorptiometry to assess changes in whole body and regional (i.e., trunk, legs, arms) fat mass, lean mass, and bone mineral content body composition adaptations in 31 healthy women pre-, mid-, and post-6 mo of periodized physical training. These results were compared with those of 1) a control group of women who had not undergone the training program and were assessed pre- and post-6 mo and 2) a group of 18 men that was tested only once. Additionally, magnetic resonance imaging was used to assess changes in muscle morphology of the thigh in a subset of 11 members of the training group. Physical training consisted of a combination of aerobic and resistance exercise in which the subjects engaged for 5 days/wk for 24 wk. Overall, the training group experienced a 2.2% decrease, a 10% decrease, and a 2.2% increase for body mass, fat mass, and soft tissue lean mass, respectively. No changes in bone mineral content were detected. The women had less of their soft tissue lean mass distributed in their arms than did the men, both before and after the women were trained. Novel to this study were the striking differences in the responses in the tissue composition of the arms (31% loss in fat mass but no change in lean mass) compared with the legs (5.5% gain in lean mass but no change in fat mass). There was a 12% fat loss in the trunk with no change in soft tissue lean mass. Dual-energy X-ray absorptiometry and magnetic resonance imaging fat mass measurements showed good agreement (r = 0. 72-0.92); their lean mass measurements were similar as well, showing approximately 5.5% increases in leg lean tissue. These findings show the importance of considering regional body composition changes, rather than whole body changes alone when assessing the effects of a periodized physical training program.

Complete remission of pulmonary spindle cell carcinoma after treatment with oral germanium sesquioxide.

Spindle cell carcinoma (SCC) is a rare form of lung cancer representing 0.2 to 0.3% of all primary pulmonary malignancies. Even with combined surgery, chemotherapy, and radiation therapy, these tumors are associated with a poor prognosis and only 10% of patients survive 2 years after diagnosis. We describe a patient with an unresectable SCC who, following no response to conventional treatment with combined modality therapy, chose to medicate herself with daily doses of germanium obtained in a health food store. She noted prompt symptomatic improvement and remains clinically and radiographically free of disease 42 months after starting her alternative therapy.

The effect of Cys LT1 receptor blockade on airway responses to allergen.

STUDY OBJECTIVE: To evaluate the effect of a potent experimental leukotriene receptor antagonist, MK-571, on airway responses to inhaled allergen. DESIGN: Randomized, double-blind, placebo-controlled, crossover trial. SETTING: Clinical research center. SUBJECTS: Eight male volunteers with allergic asthma. INTERVENTIONS: An intravenous loading dose was followed by an 8-hour infusion of MK-571 or placebo, with a 7- to 14-day washout between treatments. Allergen challenge was performed after the loading dose and a histamine challenge was performed before and 24 hours after allergen. MEASUREMENTS AND MAIN RESULTS: Forced expiratory volume in 1 second was measured serially. MK-571 provided about 50% protection during maximum early and late responses compared with placebo (p=0.005), but airway obstruction persisted 8-24 hours after allergen on both treatment days. Airway responsiveness to histamine was not significantly attenuated at 24 hours. CONCLUSION: Blocking Cys LT1 receptors for 8 hours attenuated the early and late responses but did not interrupt the cascade of events leading to subsequent allergen-induced airway obstruction and hyperreactivity.

Cross-validation of three jump power equations.

UNLABELLED: The vertical jump-and-reach score is used as a component in the estimation of peak mechanical power in two equations put forth by Lewis and Harman et al. PURPOSE: The purpose of the present study was to: 1) cross-validate the two equations using the vertical jump-and-reach test, 2) develop a more accurate equation from a large heterogeneous population, 3) analyze gender differences and jump protocols, and 4) assess Predicted Residual Sum of Squares (PRESS) as a cross-validation procedure. METHODS: One hundred eight college-age male and female athletes and nonathletes were tested on a force platform. They performed three maximal effort vertical jumps each of the squat jump (SJ) and countermovement jump (CMJ) while simultaneously performing the vertical jump-and-reach test. Regression analysis was used to predict peak power from body mass and vertical jump height. RESULTS: SJ data yielded a better power prediction equation than did CMJ data because of the greater variability in CMJ technique. The following equation was derived from SJ data: Peak Power (W) = 60.7x (jump height cm]) +45.3x(body mass [kg])-2055. This equation revealed greater accuracy than either the Lewis or previous Harman et al. equations and underestimated peak power by less than 1%, with a SEE of 355.0 W using SJ protocol. The use of one equation for both males and females resulted in only a slight (5% of power output) difference between genders. Using CMJ data in the SJ-derived equation resulted in only a 2.7% overestimation of peak power. Cross-validation of regression equations using PRESS reveals accurate and reliable R2 and SEE values. CONCLUSIONS: The SJ equation is a slightly more accurate equation than that derived from CMJ data. This equation should be used in the determination of peak power in place of the formulas developed by both Harman et al. and Lewis. Separate equations for males and females are unnecessary.

FDG SPECT in patients with lung masses.

STUDY OBJECTIVES: To determine whether 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) single-photon emission CT (SPECT) is useful in characterizing pulmonary masses. DESIGN: Scans were prospectively acquired and interpreted. Interpretations were performed with CT or chest radiograph but interpreters were blinded to eventual diagnosis. SETTING: University hospital practice and affiliated Veterans Administration medical center. PATIENTS OR PARTICIPANTS: Forty patients participated as part of an institutional review board-approved research protocol, and informed consent was obtained in all. Eight additional patient scans were acquired as part of their clinical evaluation for pulmonary mass. MEASUREMENTS AND RESULTS: There were 26 malignant lesions (12 were 1 to 2 cm in size, the rest were larger) and 17 benign lesions (3 were < 1 cm in size, 9 were 1 to 2 cm in size, and 5 were larger). Averaged sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 50% (12 of 24), 94% (17 of 18), 92% (12 of 13), and 59% (17 of 29) for lesions 1 to 2 cm in size, 100% (28 of 28), 90% (9 of 10), 97% (28 of 29), and 100% (9 of 9) for lesions > 2 cm in size. There was good correlation between readers (p < 0.0001). CONCLUSION: FDG SPECT is useful in characterizing pulmonary masses > 2 cm in size and appears to be equivalent to positron emission tomography for these lesions. Although currently clinically suboptimal for characterizing lesions < or = 2 cm in size, FDG SPECT appears to be better than current anatomic imaging methods. In addition, the positive predictive value of FDG SPECT for small lesions is also high (92%), and this technique appears potentially useful in the subset of patients in whom a positive result would alter clinical diagnostic pathways or care.

Acute hormonal responses to a single bout of heavy resistance exercise in trained power lifters and untrained men.

The purpose of this study was to investigate the acute responses of both stress and fluid regulatory hormones to a single bout of resistance exercise in both trained and untrained men. Seven competitive power lifters (PL) and 12 untrained subjects (UT) performed one set of the leg press exercise to exhaustion at 80% of their respective one-repetition maximum. Blood samples were obtained twice prior to exercise (at P1 and P2), immediately postexercise (IP), and at 5 minutes postexercise (5PE). Compared to P1 and P2, plasma epinephrine, norepinephrine, dopamine, atrial peptide, osmolality, and blood lactic acid increased significantly (p < or = 0.05) at IP. Plasma epinephrine, norepinephrine, atrial peptide, and blood lactic acid concentrations remained elevated at 5PE compared to P1 and P2. Plasma renin activity and angiotensin II were significantly elevated at 5PE compared to P1, P2, and IP, and this increase was significantly greater in PL compared to UT at 5PE. These data indicate that an acute bout of resistance exercise dramatically affects secretion of stress and fluid regulatory hormones.

Moving a graveyard: how one school prepared the way for continuous curriculum renewal.

From 1991 to 1996, the faculty at the University of Florida College of Medicine initiated several significant changes in its curriculum. These changes, included the introduction of early clinical experience in primary care settings; the enhancement of active learning experiences in small-group settings; production and use of computer-based interactive learning materials; increased clinical teaching in the ambulatory care training in an interdisciplinary primary care clerkship; effective course and faculty evaluation; establishment and use of an assessment center for instruction and performance-based evaluations utilizing standardized patients; creation of a medical education center as the focal point for logistics support of the teaching faculty and education data handling; creation of a faculty development program; and initiation of mission-based budgeting based on the faculty's teaching effort and quality. Because the faculty were relatively conservative, it was important to identify variables that would facilitate the introduction of changes and those that might hinder it. The following factors were most important: interest and support by the dean and clearly defined delegation of authority to an associate dean; introduction of a mission-based budgeting process that allocates education funds on the basis of faculty teaching effort and its quality; a clear understanding of the empowerment of the curriculum committee; and an identification of the principles that should guide educational planning and implementation. These efforts are considered the beginning of the continuous renewal needed to respond to information networking, scientific and technological innovations, and the fundamental changes in health care delivery. As these changes have taken place, a shift toward greater institutional control of the educational program leading to the MD degree has been evident.

Early phase differential effects of slow and fast barbell squat training.

To examine the importance of resistance training movement speed, two groups of women (24 +/- 4 years, 162 +/- 5 cm, 59 +/- 7 kg) squatted repeatedly at 1) 2 seconds up, 2 seconds down (slow, N = 11); or 2) 1 second up, 1 second down (fast, N = 10), doing three warm-up sets and three eight-repetition maximum sets, three times per week for 7 weeks. Tests included force platform and video analysis of the vertical jump, long jump, and maximum squat, and isometric and isokinetic knee extensor testing at speeds from 25 to 125 deg/sec. The groups improved similarly in many variables with training but also showed some differences. In the long jump, the fast group was superior in numerous variables including knee peak velocity and total-body vertical and absolute power. In the vertical jump, fast training affected the ankle and hip more (e.g., average power), and slow training mostly affected the knee (average torque). In isokinetic testing, the fast group improved strength most at the faster velocities, while the slow group strength changes were consistent across the velocities tested. Although both slow and fast training improved performance, faster training showed some advantages in quantity and magnitude of training effects.

Valproate-associated carnitine deficiency and malignant cerebral edema in the absence of hepatic failure.

We describe a 27-year-old woman who developed encephalopathy and cerebral edema during treatment of refractory complex partial seizures that included acute administration of valproate (VPA) at a dosage of 35 mg/kg per day. Multiple random VPA levels were within therapeutic range, and results of liver function studies did not show evidence of hepatic failure. Cerebral computerized tomography (CT) showed evidence of massive cerebral edema with central herniation. Just prior to death, plasma levels of free and acyl carnitines were markedly decreased. Analysis of urinary organic acids showed increased excretion of lactate, but a normal distribution of VPA metabolites. Carnitine deficiency may predispose patients to the development of coma and life-threatening cerebral edema associated with acute administration of VPA, even in the absence of concomitant hepatic failure. We suggest specific guidelines for the evaluation and management of altered consciousness in patients with seizures receiving VPA.

Use of allergen bronchoprovocation to screen drugs for anti-asthma activity.

In the atopic patient with asthma, allergens are an important cause of chronic airway inflammation and symptoms. Natural exposure to seasonal allergens, such as grass pollen, may result in exacerbation of asthma, increased airway responsiveness (i.e., increased susceptibility of the airways to constrict), and an increased frequency of emergency room visits. Removal of patients from exposure to indoor allergens, such as dust mites, results in a marked reduction in symptoms, less airway responsiveness, and a decrease in drug requirements. In the pulmonary function laboratory, inhalation of increasing doses of allergen, in a safe and controlled manner (allergen bronchoprovocation), produces physiological responses similar to those observed after natural exposure. These include an immediate decrease in the forced expiratory volume in 1 second (FEV1) that is rapid in onset but short in duration (early response), a subsequent gradual decline in FEV1 4-8 hours after allergen inhalation that is sustained (late response), an increase in airway responsiveness, and infiltration of the airway mucosa by inflammatory cells. Drugs that are effective as maintenance therapy for chronic asthma generally attenuate the late response to allergen bronchoprovocation, and those with antiinflammatory effects (e.g., inhaled corticosteroids) also attenuate the allergen-induced increase in airway responsiveness and cellular infiltration of the airways. However, the magnitude of drug effect in this clinical model does not correlate well with the drug's relative efficacy in chronic asthma. In contrast, drugs that have no effect in this clinical model, such as calcium channel blockers, ketotifen, and antihistamines, are ineffective as maintenance therapy for chronic asthma. Thus, it appears that allergen bronchoprovocation is most useful as a screening tool for excluding drugs that are unlikely to be effective for chronic asthma and for determining whether a drug has antiinflammatory and/or immunomodulatory actions on the airway mucosa.

Increased urinary excretion of LTE4 after exercise and attenuation of exercise-induced bronchospasm by montelukast, a cysteinyl leukotriene receptor antagonist.

BACKGROUND: A study was undertaken to determine whether montelukast, a new potent cysteinyl leukotriene receptor antagonist, attenuates exercise-induced bronchoconstriction. The relationship between the urinary excretion of LTE4 and exercise-induced bronchoconstriction was also investigated. METHODS: Nineteen non-smoking asthmatic patients with a forced expiratory volume in one second (FEV1) of > or = 65% of the predicted value and a reproducible fall in FEV1 after exercise of at least 20% were enrolled. Subjects received placebo and montelukast 100 mg once daily in the evening or 50 mg twice daily, each for two days, in a three-period, randomised, double blind, crossover design. In the evening, approximately 20-24 hours after the once daily dose or 12 hours after the twice daily dose, a standardised exercise challenge was performed. Data from 14 patients were available for complete analysis. RESULTS: The mean (SD) maximal percentage decrease in FEV1 after exercise was 29.6 (16.0), 17.1 (8.2), and 14.0 (9.4) for placebo, once daily, and twice daily regimens, respectively. The mean (95% CI) percentage protection was 37 (15 to 59) for the group who received 50 mg twice daily and 50 (31 to 69) for those who received 100 mg once daily. Active treatments were not different from each other. The mean (SD) plasma concentrations of montelukast were higher after the twice daily regimen (1.27 (0.81) microgram/ml) than after the once daily regimen (0.12 (0.09) microgram/ml); there was no correlation between the percentage protection against exercise-induced bronchoconstriction and plasma concentrations. After exercise urinary excretion of LTE4 increased significantly during placebo treatment (from 34.3 to 73.7 pg/mg creatinine; p < 0.05) but did not correlate with the extent of exercise-induced bronchoconstriction. CONCLUSIONS: Montelukast protects similarly against exercise-induced bronchoconstriction between plasma concentrations of 0.12 and 1.27 micrograms/ml. The increase in the urinary excretion of LTE4 after exercise and the protection from exercise-induced bronchoconstriction with a cysteinyl leukotriene receptor antagonist provide further evidence of the role of leukotrienes in the pathogenesis of exercise-induced bronchoconstriction.

Validity of an anthropometric estimate of thigh muscle cross-sectional area.

This study examined the validity of an anthropometric estimate of thigh muscle cross-sectional area using magnetic resonance imaging (MRI). The anthropometric model assumed that a cross section of the thigh could be represented as a circle with concentric circular layers of fat-plus-skin, muscle, and bone tissue. On 18 healthy, active men and women (mean +/- SD age = 23 +/- 5 yr), total thigh circumference (CT) was measured with a fiberglass tape, fat-plus-skin thickness was measured over the quadriceps (SQ) using calipers, and the distance across the medial and lateral femoral epicondyle (dE) was measured with calipers. Direct measurements of each tissue were obtained by planimetry of an MRI image taken at the same site as the circumference and skinfolds. Thigh muscle cross-sectional area (AM) was estimated as follows: [equation: see text] Mean +/- SD AM from MRI and anthropometry were 121.9 +/- 35.1 cm2 and 149.1 +/- 34.1 cm2 (r = 0.96, SEE = 10.1 cm2), respectively. Errors in the anthropometric approximations of AM were due to an overestimate of the total thigh cross-sectional area and an underestimate of fat-plus-skin compartment. Because of the close relationship between MRI and anthropometric estimates of AM, zero-intercept regression was used to produce the following final equation, applicable for use in populations studies of young, healthy, active men and women: [equation: see text]

Muscle fatigue and exhaustion during dynamic leg exercise in normoxia and hypobaric hypoxia.

Using an exercise device that integrates maximal voluntary static contraction (MVC) of knee extensor muscles with dynamic knee extension, we compared progressive muscle fatigue, i.e., rate of decline in force-generating capacity, in normoxia (758 Torr) and hypobaric hypoxia (464 Torr). Eight healthy men performed exhaustive constant work rate knee extension (21 +/- 3 W, 79 +/- 2 and 87 +/- 2% of 1-leg knee extension O2 peak uptake for normoxia and hypobaria, respectively) from knee angles of 90-150 degrees at a rate of 1 Hz. MVC (90 degrees knee angle) was performed before dynamic exercise and during < or = 5-s pauses every 2 min of dynamic exercise. MVC force was 578 +/- 29 N in normoxia and 569 +/- 29 N in hypobaria before exercise and fell, at exhaustion, to similar levels (265 +/- 10 and 284 +/- 20 N for normoxia and hypobaria, respectively; P > 0.05) that were higher (P < 0.01) than peak force of constant work rate knee extension (98 +/- 10 N, 18 +/- 3% of MVC). Time to exhaustion was 56% shorter for hypobaria than for normoxia (19 +/- 5 vs. 43 +/- 7 min, respectively; P < 0.01), and rate of right leg MVC fall was nearly twofold greater for hypobaria than for normoxia (mean slope = -22.3 vs. -11.9 N/min, respectively; P < 0.05). With increasing duration of dynamic exercise for normoxia and hypobaria, integrated electromyographic activity during MVC fell progressively with MVC force, implying attenuated maximal muscle excitation. Exhaustion, per se, was postulated to related more closely to impaired shortening velocity than to failure of force-generating capacity.

Lower limb morphology and risk of overuse injury among male infantry trainees.

The effect of anatomic variation on the risk of overuse injuries has not been adequately evaluated. To determine the association of several common anatomic characteristics (genu varum, genu valgum, genu recurvatum, and lower limb length differences) with risk of overuse injury, we made prospective morphologic measurements of young men prior to beginning 12 week of Army infantry training. The training included frequent running, marching, calisthenics, and other vigorous activities. Lower extremity anatomic landmarks were high-lighted, and front- and side-view photographic slides were taken of the 294 study volunteers. The slides were compute digitized, and the following measures calculated: pelvic width to knee width ratio (to assess genu valgum/varum), quadriceps angle (Q-angle), knee angle at full extension, and lower limb length differences. The cumulative incidence of lower limb overuse injury was 30%. Relative risk of (RR) of overuse injury was significantly higher among participants with the most valgus knees (RR = 1.9). Those with Q-angle of more than 15 degrees had significantly increased risk specifically for stress fractures (RR = 5.4). Anatomic characteristics were associated with several other types of injuries, including pain and nonacute muscle strain due to overuse. This pilot study provides evidence that some lower limb morphologic characteristics may place individuals at increased risk of overuse injuries.

Load carriage using packs: a review of physiological, biomechanical and medical aspects.

This paper reviews the biomedical aspects of transporting loads in packs and offers suggestions for improving load-carriage capability. Locating the load mass as close as possible to the body center of gravity appears to result in the lowest energy cost when carrying a pack. Thus, the double pack (half the load on the front of the body and half the load on the back) has a lower energy cost than the backpack. However, backpacks provide greater versatility in most situations. The energy cost of walking with backpack loads increases progressively with increases in load mass, body mass, walking speed or grade; type of terrain also influences energy cost. Predictive equations have been developed for estimating the energy cost of carrying loads during locomotion but these may not be accurate for prolonged (>2 h) or downhill carriage. Training with loads can result in greater energy efficiency since walking with backpack loads over several weeks decreases energy cost. Load-carriage speed can be increased with physical training that involves regular running and resistance training. Erector spinae electrical activity (EMG) is lower during load carriage than in unloaded walking until loads exceed 30-40 kg, at which point erector spinae EMG activity is higher than during unloaded walking. EMGs of the quadriceps and gastrocnemius, but not the tibialis anterior or hamstrings, increase with load. Framed packs with hip belts reduce the electrical activity of the trapezius muscles, presumably by shifting forces from the shoulders to the hips. Increases in the backpack load mass result in increases in forces exerted on the grounds, amount of knee flexion and the forward inclination of the trunk. Compared to backpacks, double packs produce fewer deviations from normal walking. Common injuries associated with prolonged load carriage include foot blisters, stress fractures, back strains, metatarsalgia (foot pain), rucksack palsy (shoulder traction injury) and knee pain. Closed-cell neoprene insoles and use of an acrylic or nylon sock, combined with a wool sock, reduce blister incidence. A framed pack with a hip belt reduces the incidence of rucksack palsy. Backpack load carriage can be facilitated by lightening loads, optimizing equipment, improving load distribution and by preventive action aimed at reducing the incidence of injury.