Energy costs & performance of transtibial amputees & non-amputees during walking & running.

This study compared energy costs and performance differences of walking and running for transtibial amputee (TTA) and matched non-amputee runners. TTA were tested with 3 prosthetic feet: traditional foot, SACH; general purpose, energy storing and return (ESAR) foot, Renegade; running-specific ESAR foot, Nitro. During walking, VO2 and gait efficiency (GE) were similar between prosthetic feet. VO2 was increased (21-33%) and GE was decreased for TTA compared to controls. Self-selected walking speed (SSWS) was slower for SACH (4-6%) compared to Renegade and Nitro but SSWS for TTA was slower (16-22%) than controls. During running, VO2 was increased (8-18%) and GE was decreased using SACH and Renegade, compared to Nitro. During running, VO2 was greater (9-38%), GE was decreased and SSRS was slower (17-30%) for TTA, than controls. VO2 peak was similar for controls and TTA using Nitro, but peak running speed was slower for TTA. In conclusion, during walking energy costs are mostly similar between prosthetic feet, but ESAR feet likely provide faster SSWS for TTA. During running, energy costs and performance are improved for TTA using Nitro. Nonetheless, for all prosthetic feet conditions, TTA demonstrated an energy cost and performance disadvantage during walking and running compared to non-amputee runners.

Metabolic demands of rock climbing in transfemoral amputees.

This pilot study compared the energy expenditure required to climb an indoor rock wall, in amputees utilizing five prosthetic configurations. Three experienced climbers (1M age 21 yr, 2F ages 30 and 49 yr) with unilateral transfemoral amputation climbed a 9.14 m indoor rock wall, 5.9 Yosemite Decimal Scale rating, using the following prosthetic configurations: 1. no prosthesis; 2. stubby prosthesis-foot forward; 3. stubby prosthesis-foot backward; 4. articulated prosthesis-knee unlocked; 5. articulated prosthesis-knee locked. Subjects climbed three times with each configuration resulting in 15 climbs per subject. Metabolic data was collected using the COSMED K4b(2) system. VO(2) was 15, 18 and 20% greater in the articulated unlocked condition (mean+/-SE: 20.5+/-0.8 ml.kg (-1).min (-1)), and 11, 13 and 15% greater in the articulated locked condition (19.7+/-0.9 ml.kg (-1).min (-1)), compared to the no prosthesis (17.8+/-0.7 ml.kg (-1).min (-1)), stubby backward (17.4+/-0.7 ml.kg (-1).min (-1)) and stubby forward (17.1+/-0.9 ml.kg (-1).min (-1)) conditions. Participants expended 11-20% more energy using the articulated prostheses than with the stubby and no prosthesis conditions. In persons with transfemoral amputation, use of an articulated prosthesis in indoor rock climbing may be a disadvantage in many aspects including competition, training, rehabilitation and satisfaction with the activity.

Biomechanical and metabolic effects of varying backpack loading on simulated marching.

Twelve healthy, male Army recruits performed three, 40-min treadmill marches at 6 km/h, under three load carriage conditions: 0%-body weight (BW) backpack load, 15%-BW load and 30%-BW load. Kinematic and kinetic data were obtained, immediately before and after each treadmill march, for computing ankle, knee and hip joint rotations and moments. Metabolic data (oxygen uptake (VO2), expired ventilation (VE), respiratory exchange ratio (RER)), heart rate (HR) and ratings of perceived exertion (RPE) were collected continuously during marching. Significant differences (p < or = 0.05) were observed between each load for VO2, HR and VE throughout the marches. At 40 min, relative energy costs for 0%-BW, 15%-BW and 30%-BW loads were 30, 36 and 41% VO2max, respectively. RPE responses during marching significantly differed for only the 30%-BW load and were greater than responses at 0%-BW and 15%-BW loads. During load carriage trials prior to treadmill marches (pre-march), peaks in internal, hip extension, knee extension and ankle plantar flexion moments increased with increasing backpack load. Relative to 0%-BW load, percentage increases in knee moments, due to 15%-BW and 30%-BW loads, pre-march, were substantially larger than the percentage increases for hip extension and plantar flexion moments, pre-march. Pre-march and post-march peaks in hip extension and ankle plantar flexion moments were similar with all loads, while notable pre-march to post-march declines were observed for knee extension moment peaks, at 15%-BW and 30%-BW load. Pre-march joint loading data suggests that the knee may be effecting substantial compensations during backpack loaded marching, perhaps to attenuate shock or reduce load elsewhere. Post-march kinetic data (particularly at 15%-BW and 30%-BW load), however, indicates that such knee mechanics were not sustained and suggests that excessive knee extensor fatigue may occur prior to march end, even though overall metabolic responses, at 15%-BW and 30%-BW load, remained within generally recommended limits to prevent fatigue during prolonged work.

Effects of age, physical training, and physical fitness on coronary heart disease risk factors in older track athletes at twenty-year follow-up.

OBJECTIVE: To compare current coronary heart disease (CHD) risk factor values in older athletes with mid-life measures and to examine the associations between changes in CHD risk factors with aging, physical training, and physical fitness. DESIGN: Prospective study with three longitudinal evaluation points: initial (T1), 10-year (T2), and 20-year (T3). Subjects were selected because of their elite status in Masters track competition. SETTING: University and medical center laboratories. PARTICIPANTS: Participants were 60 to 92 years of age and included 21 of the initial 27 subjects. At T3, subjects were divided into three groups, based on physical activity levels: high intensity (H), remained elite in national and international competition (n = 9); moderate intensity (M) continued frequent rigorous endurance training but rarely competed (n = 10); and low intensity (L) greatly reduced their training volume and intensity (n = 2). MEASUREMENTS: Smoking history; family history of coronary or cerebrovascular disease; resting blood pressure; resting electrocardiogram (ECG); serum total cholesterol, plasma glucose; body weight, % body fat, body mass index, waist:hip ratio; training pace and mileage; maximal oxygen consumption VO2 max). MAIN RESULTS: Several risk factors (smoking, diabetes, obesity) were never present, and the prevalence of other risk factors (family history of cardiovascular disease, abnormal resting ECG) remained low through T3 (< or = 14% of subjects). Mean systolic and diastolic blood pressure remained low without medication, but diastolic blood pressure measurements had the greatest redistribution between evaluation periods of any risk factor (r = .16, P = .479, T1 to T2). Mean total cholesterol was lower at T2 (-13%, P = .005) and T3 (-14%, P = .019) compared with T1. Change in VO2 max was correlated with changes in body weight (r = -.44, P = .048) and % fat (r = -.52, P = .015) from T1 to T2, whereas age was correlated to changes in systolic blood pressure (r = -.61, P = .003) and total cholesterol (r = -.49, P = .023) from T2 to T3. CONCLUSIONS: The prevalence of CHD risk factors remained low, and mean risk factor values remained low and generally stable in older athletes who had maintained habitual exercise training.

Twenty-year follow-up of aerobic power and body composition of older track athletes.

The purpose was to determine the aerobic power (maximal oxygen uptake) and body composition of older track athletes after a 20-yr follow-up (T3). At 20 yr, 21 subjects [mean ages: 50.5 +/- 8.5 yr at initial evaluation (T1), 60.2 +/- 8.8 yr at 10-yr follow-up (T2), and 70.4 +/- 8.8 yr at 20-yr follow-up (T3)] were divided into three intensity groups: high (H; remained elite; n = 9); moderate (M; continued frequent moderate-to-rigorous endurance training; n = 10); and low (L; greatly reduced training; n = 2). All groups decreased in maximal oxygen uptake at each testing point (H, 8 and 15%; M, 13 and 14%; and L, 18 and 34% from T1 to T2 and T2 to T3, respectively). Maximal heart rate showed a linear decrease of approximately 5-7 beats.min-1.decade-1 and was independent of training status. Body weight remained stable for the H and M groups and percent fat increased approximately 2-2.5%/decade. Although fat-free weight decreased at each testing point, there was a trend for those who began weight-training exercise to better maintain it. Cross-sectional analysis at T3 showed that leg strength and bone mineral density were generally maintained from age 60 to 89 yr. Those who performed weight training had a greater arm region bone mineral density than those who did not. These longitudinal data show that the physiological capacities of older athletes are reduced despite continued vigorous endurance exercise over a 20-yr period (approximately 8-15%/decade). Changes in body composition appeared to be less than those shown for the healthy sedentary population and were related to changes in training habits.

A review of the principles of pulse oximetry and accuracy of pulse oximeter estimates during exercise.

This article reviews the principles of pulse oximetry and assesses the accuracy of pulse oximeter measurements obtained during exercise, based on reports of 10 studies that evaluated 24 pulse oximeters. Nine of the studies used cycle exercise, and 1 study utilized treadmill running for mode of activity. Subject populations included patients with cardiovascular or pulmonary disorders, nondisabled individuals, and athletes. Studies were performed under normoxic and hypoxic conditions, and 5 of the 10 studies validated 18 pulse oximeters at arterial oxyhemoglobin saturation (%HbO2) levels of < or = 78%. Sixteen of the 24 pulse oximeters (67%), from 7 of the 10 studies, observed pulse oximeter estimates (%SpO2) during exercise to be accurate, at least when %HbO2 was > or = 85% in nonsmokers. However, the degree of accuracy of the pulse oximeters was variable, even among the same models. Recent studies suggest the current generation of finger-probe-equipped pulse oximeters may be more accurate than ear-probe-equipped models. We recommend that clinicians carefully secure the probe; monitor signal strength; be wary of %SpO2 values of < or = 68% to 78% to avoid undetected severe hypoxemia; and be alert to whether a patient is a smoker, in which case %SpO2 will likely be overestimated. Researchers interested in using pulse oximeter estimates should validate their particular pulse oximeter(s) via arterial blood sampling.

Sex pheromone of fall armyworm,Spodoptera frugiperda (J.E. Smith) : Identification of components critical to attraction in the field.

Analyses of extracts of pheromone glands and of volatiles from calling female fall armyworm moths,Spodoptera frugiperda (J.E. Smith), revealed the presence of the following compounds: dodecan-1-ol acetate, (Z)-7-dodecen-1-ol acetate, 11-dodecen-1-ol acetate, (Z)-9-tetradecenal, (Z)-9-tetradecen-1-ol acetate, (Z)-11-hexadecenal, and (Z)-11-hexadecen-1-ol acetate. The volatiles emitted by calling females differed from the gland extract in that the two aldehydes were absent. Field tests were conducted with sticky traps baited with rubber septa formulated to release blends with the same component ratios as those emitted by calling females. These tests demonstrated that both (Z)-7-dodecen-1-ol acetate and (Z)-9-tetradecen-1-ol acetate are required for optimum activity and that this blend is a significantly better lure than either virgin females or 25 mg of (Z)-9-dodecen-1-ol acetate in a polyethylene vial, the previously used standard. Addition of the other three acetates found in the volatiles did not significantly increase the effectiveness of the two-component blend as a bait for Pherocon 1C or International Pheromones moth traps.

Prediction of release ratios of multicomponent pheromones from rubber septa.

A method has been developed to predict the release ratio of the components of blends of alcohols, acetates, and/or aldehydes from rubber septa. The calculations of predicted release ratios are based on the relative vapor pressures of the components. The relative vapor pressures of the compounds were calculated from their retention indices on a liquid crystal capillary gas chromatographie column. The correlation between the theoretically predicted and experimentally determined ratios was very good. Thus, formulations can be prepared that will release a desired ratio of the components of a multicomponent pheromone blend.