Biomedical subjects

T Gwinn

Publications and source records attributed to T Gwinn.

7 recordsLinked to original sources

PubMed2002

Aerobic work capacity in elite wheelchair athletes: a cross-sectional analysis.

OBJECTIVE: To give a descriptive analysis of aerobic capacity among elite wheelchair athletes in association with various personal characteristics and sprint or anaerobic capacity. DESIGN: Sixty-eight wheelchair athletes who participated in the World Games and Championships for the Disabled were included. Parameters for aerobic capacity were evaluated in a standardized wheelchair exercise test on a computer-controlled wheelchair ergometer at the games. The ergometer setting was individually tuned according to standardized procedures. RESULTS: Mean maximum power output was 72.2 +/- 36.7 W. Peak oxygen uptake showed similar strong variations among different subject groups. High values were seen in a group of six subjects with amputations. Results stressed that, apart from sex, functionality and training status had a strong influence on aerobic capacity. Anaerobic and aerobic capacity were strongly associated. CONCLUSIONS: Functionality, training status, and sex are important determinants of aerobic capacity. The functional classification used at international sports events is represented in the data, and further study into the possible contribution of standardized exercise tests within the issue of classification must be considered. The use of standardized exercise tests for the evaluation of training and for rehabilitation progress must be advocated, with power output being an important outcome measure at the level of ability, whereas oxygen uptake represents outcome at the level of organ systems.

Adult↗

PubMed1999

Energy cost of sport rock climbing in elite performers.

OBJECTIVES: To assess oxygen uptake (VO2), blood lactate concentration ([La(b)]), and heart rate (HR) response during indoor and outdoor sport climbing. METHODS: Seven climbers aged 25 (SE 1) years, with a personal best ascent without preview or fall (on sight) ranging from 6b to 7a were assessed using an indoor vertical treadmill with artificial rock hand/foot holds and a discontinuous protocol with climbing velocity incremented until voluntary fatigue. On a separate occasion the subjects performed a 23.4 m outdoor rock climb graded 5c and taking 7 min 36 s (SE 33 s) to complete. Cardiorespiratory parameters were measured using a telemetry system and [La(b)] collected at rest and after climbing. RESULTS: Indoor climbing elicited a peak oxygen uptake (VO2climb-peak) and peak HR (HRpeak) of 43.8 (SE 2.2) ml/kg/min and 190 (SE 4) bpm, respectively and increased blood lactate concentration [La(b)] from 1.4 (0.1) to 10.2 (0.6) mmol/l (p < 0.05). During outdoor climbing VO2 and HR increased to about 75% and 83% of VO2climb-peak and HRpeak, respectively. [La(b)] increased from 1.3 (0.1) at rest to 4.5 mmol/l (p < 0.05) at 2 min 32 s (8 s) after completion of the climb. CONCLUSIONS: The results suggest that for elite climbers outdoor sport rock climbs of five to 10 minutes' duration and moderate difficulty require a significant portion of the VO2climb-peak. The higher HR and VO2 for outdoor climbing and the increased [La(b)] could be the result of repeated isometric contractions, particularly from the arm and forearm muscles.

Adult↗

PubMed1998

Flit-gun sprayer characteristics.

Six flit-gun sprayers were tested for possible use in mosquito adulticide programs where inexpensive nonmotorized application technology may be required. An analysis of variance for differences in droplets < or = 24 microns (mu), droplets > or = 48 mu, droplets/cm2, volume median diameters, and mosquito mortality is provided. As shown by these data, good results can be achieved with this equipment.

Analysis of Variance↗

PubMed1997

An electrostatic backpack sprayer: potential for mosquito control.

A Southwest Electrostatic Sprayers, Inc., nozzle was configured to a Hudson PortaPak backpack. A test was run to compare deposition of BVA no. 13 oil by the electrostatic nozzle to a standard nonelectrostatic nozzle as collected by Teflon slides. Results indicate that 100% greater deposition occurred with the electrostatic nozzle.

Mosquito Control↗

PubMed1989

Muscle strength, physical fitness, and weight but not age predict femoral neck bone mass.

Hip fractures are the most serious complication of osteoporosis. Although low proximal femoral bone mineral density (BMD) does not cause hip fractures directly, it is clearly a prerequisite for the increased risk associated with aging. To investigate the mechanism of the age-related decline in proximal femoral bone mineral density, we have examined the relative importance of muscle strength, physical fitness, and body mass index (BMI) in addition to age in the determination of proximal femoral BMD in 73 healthy female volunteers age 20-75 years. Muscle strength was an independent predictor of BMD at all three sites in the proximal femur as well as in the lumbar spine and forearm; proximal femur BMD was also predicted by physical fitness. BMI was a positive predictor of bone mass at all sites. In the proximal femur, age was not an independent predictor of BMD at any site. In postmenopausal women muscle strength was a significant predictor of bone mass in the femur and forearm, but not in the spine. However, BMI remained predictive of bone mineral at all sites. Muscle strength, physical fitness, and weight appear to exert independent effects upon bone mass. Age effects may be mediated indirectly through associated changes in these factors. The integrated physical load on the skeleton may be a final common pathway.

Adult↗

PubMedDate not supplied

Anaerobic work capacity in elite wheelchair athletes.

To study the anaerobic work capacity in wheelchair athletes, 67 elite wheelchair athletes (50 male) were studied in a 30-second sprint test on a computer-controlled wheelchair ergometer during the World Championships and Games for the Disabled in Assen (1990). The experimental set-up (ergometer, protocol) proved to be adequate in terms of power output (P30, P5) velocity and heart rate. Male and female athletes were comparable with respect to personal characteristics (age, body weight, training hours). Track athletes (classified in 4 different functional classes) showed a class-related mean power output (P30: mean power produced during the 30-second sprint period) of 23, 68, 100, and 138 W for the male athletes (n = 38) and 38, 77, and 76 W for females in the upper three classes (n = 10). Sprint power was low for the group of subjects with cerebral palsy (35 W; mixed, n = 6) and relatively high for the amputee group (121 W; mixed, n = 6), female basketball players (81 W; n = 5), and two male field athletes (110 W). Significant differences between male and female athletes were found for P30 and P5 (highest mean power output over any of the six 5-second periods). As was to be expected, mean maximum heart rate in the sprint test varied significantly between the track groups from 112 (high lesion group) to 171 beats/minute(-1) (low lesion group) but not for both genders. The lower P30 in the T1 and T2 groups must be explained not only by the reduced functional muscle mass and impaired coordination but also by phenomena of cardiovascular dysfunction. Based on the performance parameters, the functional classification of the track athletes into four groups seems adequate. P30 was significantly associated with the personal characteristics of gender and hours of training. A significant correlation was found between P30 and sprint performance times for 200 meters (r = -0.79). No correlation was found between either of the forms of power output and the marathon times. Anaerobic wheelchair work capacity can be adequately studied with the 30-second sprint test that was used in this study. Anaerobic work capacity is highly variable among elite wheelchair athletes with different disabilities and from different sports disciplines and appeared quite strongly influenced by functionality, hours of training, and gender.

Adult↗

PubMedDate not supplied

Propulsion technique and anaerobic work capacity in elite wheelchair athletes: cross-sectional analysis.

Wheelchair sports and daily manual wheelchair propulsion are dominated by frequent short-term power demands. The purpose of the current cross-sectional study was to determine the variation in propulsion technique in association with sprint power production among elite wheelchair athletes. Therefore, 67 wheelchair athletes (different impairments; 17 female and 50 male athletes; age, 29.1+/-7 yr; body weight, 60.7+/-11.8 kg; training hours, 12.9+/-6.4 h x wk(-1); VO2 peak, 1.7+/-0.7 liter x min(-1); aerobic power output, 72.2+/-36.7 W) were studied during the World Championships and Games for the Disabled in Assen (1990) on propulsion technique and anaerobic work capacity in a 30-s sprint test on a computer controlled wheelchair ergometer. Mean power output (P30) (97+/-45.8 W; range, 8.3-195.3 W) and heart rate (158.6+/-23.6 b x min(-1)) were highly variable and seemed associated with impairment level: track athletes, classified in four different functional classes, showed a class-related P30 of 23, 68, 100, and 138 W for the male athletes (n=38). Sprint power relative to body weight varied between 0.36 W X kg BW(-1)+/-0.04 and 1.85 W X kg BW(-1)+/-0.43 for the different subject groups. Propulsion technique in terms of forces applied to the rim and timing showed significant differences between subject groups for the majority of parameters studied. Apart from the mediolateral force and the negative dip at the start of the push phase, the technique parameters were significantly related to power production. Fraction effective force, the ratio between the total force vector and the effective force applied to the hand rim, appeared low on average (especially for subjects with cerebral palsy and those with a high spinal lesion) but showed a significant correlation with power output (r=0.5). In general, propulsion technique parameters were related to both performance and functionality. The number of training hours showed a small but significant relation with peak power (r=0.31), peak torque (r=0.4), the amount of work per push (r=0.41) and the total force vector (r=0.31), stressing the role of training status, next to disability, as important mediating factor in both propulsion technique as well as performance capacity. No association between training hours and fraction effective force was seen. It can be concluded that propulsion technique and performance parameters are highly variable among wheelchair athletes. Also, propulsion technique is strongly associated with functionality and training hours and does clearly relate to performance. The current results on technique and performance and their possible causal relationship, but also with impairment and sports discipline, must be further substantiated in a longitudinal study design.

Adult↗