Biomedical subjects

K D Coutts

Publications and source records attributed to K D Coutts.

At least 19 recordsLinked to original sources

PubMed2000

Metabolic responses to prolonged work during treadmill and water immersion running.

The primary aim of this study was to compare the physiological responses to prolonged treadmill (TM) and water immersion to the neck (WI) running at threshold intensity. Ten endurance runners performed TM and WI running VO2max tests. Subjects completed submaximal performance tests at ventilatory threshold (Tvent) intensities under TM and WI conditions and responses at 15 and 42 minutes examined. VO2 was lower in WI (p<0.05) at maximal effort and Tvent. The Tvent VO2 intensities interpolated from the TM and WI VO2max tests were performed in both TM (i.e., TM@TM(tvent),TM@WI(tvent), corresponding to 77.6 and 71.3% respectively of TM VO2max) and WI conditions (i.e., WI@TM(tvent), WI@WI(tvent), corresponding to 85.5% and 78.2% respectively of WI VO2max). Each of the dependent variables was analyzed using a 3-way repeated measures ANOVA (2 conditions X 2 exercise intensities X 7 time points during exercise). VO2max values were significantly lower in the WI (52.4(5.1) ml.kg(-1) min(-1)) versus TM (59.7(6.5) ml.kg(-1) min(-1)) condition. VO2 during submaximal tests were similar during the TM and WI conditions. HR and [BLa] responses to exercise at and above WI(tvent) were similar during short-term exercise, but values tended to be lower during prolonged exercise in the WI condition. There were no statistical differences in VE responses in the 2 conditions, however as with HR and [BLa] an upward trend was noted with TM exercise over the 42 minute duration of the tests. RPE at WI(tvent) was similar for TM and WI exercise sessions, however, RPE at TM(tvent) was higher during WI compared to TM running. Cardiovascular drift was observed during prolonged TM but not WI running. Results suggest differences in metabolic responses to prolonged submaximal exercise in WI, however it can be used effectively for cross training.

Adult↗

PubMed2000

Effect of body position on measurements of diffusion capacity after exercise.

BACKGROUND: Pulmonary diffusing capacity for carbon monoxide (D1co), alveolar capillary membrane diffusing capacity (Dm), and pulmonary capillary blood volume (Vc) are all significantly reduced after exercise. OBJECTIVE: To investigate whether measurement position affects this impaired gas transfer. METHODS: Before and one, two, and four hours after incremental cycle ergometer exercise to fatigue, single breath D1co, Dm, and Vc measurements were obtained in 10 healthy men in a randomly assigned supine and upright seated position. RESULTS: After exercise, D1co, Dm, and Vc were significantly depressed compared with baseline in both positions. The supine position produced significantly higher values over time for D1co (5.22 (0.13) v. 4.66 (0.15) ml/min/mm Hg/l, p = 0.022) and Dm (6.78 (0.19) v. 6.03 (0.19) ml/min/mm Hg/l, p = 0.016), but there was no significant position effect for Vc. There was a similar pattern of change over time for D1co, Dm, and Vc in the two positions. CONCLUSIONS: The change in D1co after exercise appears to be primarily due to a decrease in Vc. Although the mechanism for the reduction in Vc cannot be determined from these data, passive relocation of blood to the periphery as the result of gravity can be discounted, suggesting that active vasoconstriction of the pulmonary vasculature and/or peripheral vasodilatation is occurring after exercise.

Adult↗

PubMed1999

Aerobic and anaerobic energy during a 2-km race simulation in female rowers.

The maximal aerobic power (VO2max) and maximal anaerobic capacity (AODmax) of 16 female rowers were compared to their peak aerobic power (VO2peak) and peak anaerobic capacity (AODpeak, respectively) during a simulated 2-km race on a rowing ergometer. Each subject completed three tests, which included a 2-min maximal effort bout to determine the AODmax, a series of four, 4-min submaximal stages with subsequent progression to VO2max and a simulated 2-km race. Aerobic power was determined using an open-circuit system, and the accumulated oxygen deficit method was used to calculate anaerobic capacities from recorded mechanical power on a rowing ergometer. The average VO2peak (3.58 l min(-1)), which usually occurred during the last minute of the race simulation, was not significantly different (P > 0.05) from the VO2max (3.55 l min(-1)). In addition, the rowers' AODmax (3.40 l) was not significantly different (P > 0.05) from their AODpeak (3.50 1). The average time taken for the rowers to complete the 2-km race simulation was 7.5 min, and the anaerobic system (AODpeak) accounted for 12% of the rowers' total energy production during the race.

Adult↗

PubMed1999

The effect of repeat exercise on pulmonary diffusing capacity and EIH in trained athletes.

PURPOSE: The purpose of this study was to determine the effects of repeated heavy exercise on postexercise pulmonary diffusing capacity (DL) and the development of exercise induced arterial hypoxemia (EIH). METHODS: 13 endurance-trained, male athletes (age = 27+/-3 yr, height = 179.6+/-5.0 cm, weight = 71.8+/-6.9 kg, VO2max = 67.0+/-3.6 mL x kg(-1) x min(-1) performed two consecutive, continuous exercise tests on a cycle ergometer to VO2max, separated by 60 min of recovery. Arterial oxygen saturation (%SaO2) was measured via ear oximetry, and resting DL was measured and partitioned by the single-breath method, before exercise and 60 min after each exercise bout. RESULTS: No significant differences resulted in VO2max, VE, peak heart rate (HR), or breathing frequency between exercise bouts (P > 0.05). There was a small but significant decrease (454-446 W; P < 0.05) in peak power output in the second test. %SaO2 decreased from resting values during both exercise tasks, but there was no difference between the minimum saturation achieved in test 1 (91.4) or test 2 (91.6; P > 0.05). After the initial exercise bout, significant decreases (P < 0.05) occurred in DL (11%), membrane diffusing capacity (DM) (11%) and pulmonary capillary volume (VC) (10%). Further decreases occurred in DL (6%; P < 0.05), DM (2%; P > 0.05), and VC (10%; P < 0.05) after the second exercise bout. CONCLUSIONS: These observations question the meaning of post exercise measurements of pulmonary diffusion capacity, and its components, relative to pulmonary gas exchange and pulmonary fluid accumulation during exercise. The fact that there was no further change in %SaO2 after the second test suggests that if any interstitial edema developed, it was of no clinical significance; alternatively, the changes in DL(CO) may be related more to redistribution of blood than the development of pulmonary edema.

Adult↗

PubMed1998

The time course of pulmonary diffusing capacity for carbon monoxide following short duration high intensity exercise.

We investigated the time course of changes in post-exercise pulmonary diffusing capacity for carbon monoxide (DLCO), membrane diffusing capacity (DM), and pulmonary capillary blood volume (VC) in highly trained (HT), moderately trained (MT) and untrained (UT) male subjects (n = 8/group). Subjects were assigned to groups based on their aerobic capacity from a preliminary VO2max test (HT > or = 65, MT = 50-60, UT < or = 50 ml x kg(-1) x min(-1)). Resting (BASE) DLCO, DM and VC were obtained, then subjects cycled to fatigue at the highest workrate attained during the preliminary tests. Diffusion measurements were then made at 1, 2, 4, 6 and 24 h. DLCO was depressed at 1 h, lowest at 6 h and approached BASE values at 24 h in all groups. The DLCO change was paralleled by a change in VC. Alterations to VC were similar between groups except at 24 h where MT and HT subjects had returned to BASE while UT did not. DM was significantly lower than BASE at 1, 2, 4, and 6 h, and was similar between groups. The changes in DLCO post-exercise appear to be primarily due to a decrease in VC. Comparable diffusion decrements were observed in all subjects. The results of this study suggest that post-exercise alterations in DLCO, DM and VC are not related to aerobic capacity.

Bicycling↗

PubMed1996

The relationship between test protocol and the development of exercise-induced hypoxemia (EIH) in highly trained athletes.

Healthy male endurance-trained cyclists [n = 11, age = 27.3 (3.9) years; mass = 73.0 (9.3) kg; height = 180.5 (6.9) cm; maximal oxygen consumption (VO2max) = 71.1 (5.8) ml.kg-1.min-1, mean +/- (SD)] were recruited to assess the relationship between test protocol and the development of desaturation of arterial hemoglobin with oxygen, during incremental exercise tests to maximal aerobic capacity (VO2max). All subjects demonstrated resting pulmonary function within normal limits [forced vital capacity (FVC) = 6.0 (0.9); forced expiratory volume (FEV1.0) = 4.9 (0.6); FEV1.0/FVC = 0.8 (0.1)] and completed three ramped VO2max tests (Mijnhardt KEM-3 electronically braked cycle ergometer) beginning at 0 W with increments of either 20,30 or 40 W.min-1. All periods of testing were separated by a minimum of 72 h. VO2max, peak minute ventilation (VEpeak) (Medical Graphics, CPX-D), peak heart rate (fcpeak), peak power output (Wpeak), and minimum percentage arterial oxyhemoglobin saturation (% SaO2min) (Omeda Biox 3740 pulse oximeter) were determined. There were no significant differences (p > 0.05) in VEpeak [191.5 (26.2), 196.0 (24.4), 194.3 (23.9) l.min-1] fcpeak [191.4 (7.0), 190.3 (5.5), 187.8 (5.9) beats.min-1], VO2max [5.0 (0.5), 5.1 (0.4), 5.1 (0.5) l.min-1] or %SaO2min [89.5 (1.5), 89.6 (1.3), 90.0 (2.3)] between protocols. The 20-W protocol [417 (27) W] demonstrated significantly lower Wpeak (P < 0.05) than the 30-W [434 (36) W] and 40-W [453 (38) W] protocols, indicating that peripheral fatigue may play an important factor in response to these tests. The results of this study demonstrate that arterial desaturation occurs as a result of intense exercise in highly trained athletes independent of the rate of attainment of VO2max.

Adult↗

PubMed1996

Comparison of aero-bars versus traditional cycling postures on physiological parameters during submaximal cycling.

The purpose of this investigation was to quantify the difference in energy expenditure between traditional cycling handlebars and aero-bars during outdoor submaximal cycling. Eleven trained cyclists (age = 29.3 +/- 1.9 years, weight = 69.4 +/- 3.8 kg, VO2max = 58.1 +/- 2.0 ml.kg-1.min-1) were randomly assigned a sequence of three hand positions: brake hoods (BH), drop-bars (DB), and aero-bars (AB). Subjects cycled at 30 km.h-1 in one position for 5 minutes, then recovered until HR fell below 120 bpm. This was then repeated for the other hand positions. All cycling was completed on a standard racing bike fitted with aero-bars. Tire pressure was held constant for all trials. A portable telemetric system (Cosmed K-2) was used to measure VO2, VE and heart rate (HR) during the trials. No statistical differences were observed between AB and DB. Significant differences (p < .05) were found between BH (VE = 66.1 +/- 2.7 L.min-1; HR = 152 +/- 4 bpm; VO2 = 1.56 +/- .15 L.min-1) and AB (VE = 61.3 +/- 2.8 L.min-1; HR = 146 +/- 4 bpm; VO2 = 1.31 +/- .10 L.min-1). AB provides an energy savings over the traditional BH cycling posture.

Adolescent↗

PubMed1996

Physical fitness and its relationship to other indices of health status in children with chronic arthritis.

OBJECTIVE: To compare aerobic and anaerobic fitness of a group of children w-th chronic arthritis with that of healthy controls, and to explore the relationship between physical fitness and other indices of health status in these children. METHODS: Thirty-one children aged 8 to 17 years with chronic arthritis of varying type and severity and 16 physically healthy controls participated in the study. Using a cycle ergometer, aerobic fitness was assessed by measuring peak oxygen uptake achieved in a 15 s period during exercise to volitional fatigue. Anaerobic fitness was assessed by measuring peak power in the legs in a 5 s period and total work completed (Wingate test). Joint pain experienced over the week before testing and during testing was measured using a 10 cm visual analog scale. Self-esteem was measured using the Self Perception Profile for Children Questionnaire. RESULTS: There were no significant differences between mean peak O2 uptake or mean peak anaerobic power for patients and controls; however, the mean values for both controls and patients were significantly lower than reported values for healthy children. Peak O2 uptake controlled for age, sex, and sum of skinfolds was negatively associated with disease severity, measured by physician global assessment (p = 0.04), but peak power was not. Neither aerobic nor anaerobic fitness were associated with disease activity measured by physician global assessment or active joint count, or with disease duration. There was a tendency for children with active arthritis to experience less pain during fitness testing than over the previous week (p = 0.06). Testing did not seem to exacerbate joint symptoms. Self-ratings of athletic competence were significantly correlated with peak O2 uptake achieved for children with arthritis (r = 0.43, p = 0.02), but not for controls. Global self-esteem was moderately correlated with self-rated athletic competence in controls (r = 0.49, p = 0.09), but was not in children with arthritis. CONCLUSION: In this sample of children, most of whom had limited joint involvement, we failed to demonstrate significant group differences in fitness between patients and controls. Disease severity may be related to fitness levels, but psychosocial factors may perhaps be more important determinants of fitness. Children with arthritis seem to have realistic perceptions of their own physical capabilities, and even those children who are less fit and perceive themselves as having less athletic competence do not appear to have lowered self-esteem.

Adolescent↗

PubMed1995

Ventilatory thresholds during wheelchair exercise in individuals with spinal cord injuries.

The ventilatory thresholds of 30 male wheelchair athletes were determined from their respiratory and metabolic responses to a continuously progressive exercise protocol to peak oxygen uptake on a wheelchair ergometer. The peak oxygen uptake (peak VO2), ventilatory threshold in 1 min-1 (VTL), and ventilatory threshold expressed as a percentage of peak VO2 (VT%) were measured for all subjects. Statistical analyses of selected subsamples were used to note sport and functional ability level differences in these variables. Analysis of peak VO2 by functional classification (old International Stoke Mandeville Games Federation system; classes 1A-5, plus an amputee class) indicated that paraplegic (classes 2-5) and the amputee class athletes (2.48 1 min-1) were higher than tetraplegic (classes 1A-1C) athletes (0.95 1 min-1). The paraplegic and amputee classes were combined for a comparison of peak VO2 by sport which showed that track athletes (2.80 1 min-1) were higher than basketball players (2.41 1 min-1) who were higher than athletes from other sports (1.88 1 min-1). The VTL analyses demonstrated differences similar to the peak VO2 analyses. The VT% analyses, however, showed no sport differences, but the tetraplegic athletes had higher VT% values (87%) than the paraplegic plus amputee group (69%).

Adult↗

PubMed1994

Drag and sprint performance of wheelchair basketball players.

The purpose of this study was to measure the wheelchair drag and maximal sprint performance abilities of wheelchair basketball players and to make comparisons between male and female players. A group of nine male and eight female wheelchair basketball players attending a national training camp consented to serve as subjects. Each subject completed six coast-down trials at speeds from a walking pace (1 to 1.5 m/s) to maximal for determining wheelchair drag and then performed four maximal sprint trials from a stationary start over the length (35 m) of the gymnasium floor. A portable computer that recorded the time to the nearest 0.001 second of each half revolution of a rear wheel was attached to the wheelchair of each subject. The drag force during the coast-down trials and the power output during the sprint trials were determined from the recorded data. Differences between the genders in a number of subject and trial variables were evaluated by t-tests using the 0.05 level of significance. There were no significant differences between the means of the male and female groups in age (27 vs. 28 yrs), wheelchair mass (12.0 vs. 11.61 kg), or regression predicted drag forces at speeds of 2 m/s (5.3 vs. 5.5 N) and 5 m/s (16.7 vs. 13.5 N). The male subjects were significantly heavier (78.3 vs. 59.1 kg) and had a higher tire pressure (123 vs. 94 psi). In the sprint trial results, the males exhibited a significantly higher maximal speed (4.75 vs. 4.08 m/s), higher peak acceleration (1.32 vs. 1.03 m/s/s), and a higher peak power output (530 vs. 264 w).

Acceleration↗

PubMed1992

Dynamics of wheelchair basketball.

A sport model wheelchair instrumented with a portable computer and a switch activated with each half revolution of a rear wheel was used to record serial time and distance data on two subjects (1 male, 1 female) during a portion of a basketball game. These and two additional subjects (1 male, 1 female) also completed a series of coast down and maximal sprint trials on the basketball court. The drag force while coasting was positively related to the mass of the subject, and the male subjects had a higher maximal speed, acceleration, force, and power output in the sprint trials. During the wheelchair basketball game, it was estimated that 64% of the time was spent in propulsive action and 36% in braking activity. Projections for a complete 40 minute game indicated that both subjects would travel about 5 km at an average speed of 2 m.s-1 and attain a peak speed of 4 m.s-1. Plots of speed and power vs time showed the intermittent nature of playing wheelchair basketball. The greater amount of propulsive work (52.6 vs 37.5 kJ) and braking ("negative") work (43.9 vs 30.8 kJ) in a game for the male subject can be related to the male's higher body mass and wheelchair drag force.

Acceleration↗

PubMed1991

Dynamic characteristics of a sport wheelchair.

A single subject performed 36 coast-down trials on a hardwood floor in a sport model wheelchair with velocity ranging from 1.28 to 5.31 m/s (4.6 to 19.1 km/h). A portable computer attached to the wheelchair was used to record the time to the nearest 0.001-second of each half-revolution of a rear wheel. The deceleration during each trial was determined with an average coefficient of variation of 2.6 percent from linear regression of velocity versus time values. A significant relationship (r = 0.97) between deceleration and the square of the velocity was noted in an analysis of the values from the 36 trials. Total drag force and power was calculated as a function of wheelchair velocity from this relationship, indicating that the power output needed to propel the wheelchair increased as a function of the velocity cubed. It is speculated that this noted exponential increase in the energy cost of wheelchair propulsion at higher speeds was due mainly to an increase in air drag.

Acceleration↗

PubMed1990

Kinematics of sport wheelchair propulsion.

Eight international caliber wheelchair male athletes (3 basketball, 5 distance track) performed an all-out propulsion effort from a standing start for 10 seconds on a wheelchair ergometer. Comparisons between the basketball and track athletes on linear wheelchair and push rim velocity during the first 3 pushes and the peak value indicated that the basketball players had a significantly (p less than .05) higher push rim velocity throughout the effort and a higher wheelchair velocity only at the end of the first push. The track athletes attained a significantly higher peak wheelchair velocity. Graphical comparison of the best individual basketball and track athletes' performances indicated that the track athletes caught up to the basketball players after about 3.7 seconds or 12 meters and travelled 49 meters in the 10 seconds, compared to 37 meters for the basketball players. Differences in push rim and wheel diameter are considered the major factor in the noted differences in propulsion kinematics of basketball and track wheelchairs.

Acceleration↗

PubMed1988

Heart rates of participants in wheelchair sports.

The relative stress of participation in wheelchair basketball, volleyball, tennis, and racquetball were determined by monitoring the heart rates of wheelchair athletes. Heart rates were recorded for 5 seconds every 30 seconds during monitoring sessions of 10 min or longer under game or practice conditions. Subjects were volunteer paraplegic athletes with lesions below T5 or with equivalent disability according to an international sport classification system. Average heart rates were 89 beats/min for tennis 'practice', 96 for racquetball 'practice' 107 for volleyball 'practice', 114 for volleyball 'game', 127 for tennis 'game', 129 for basketball 'practice', 135 for racquetball 'game', and 149 for basketball 'game' conditions. The percentage of time when heart rates were above 140 beats/min, followed the same pattern as the average heart rates and ranged from 0 to 62%.

Heart Rate↗

PubMed1988

Analysis of wheelchair track performances.

The purpose of this study was to analyze the performance in wheelchair races with respect to the level of impaired functional musculature of the athletes. The data consisted of the world records and 1984 World Wheelchair Games track finalists' performances in the seven competitive classes for males and females. Peak wheelchair record speed, regardless of level of disability, of 6.43 m.s-;1 for males occurs in the 200 m event which decreases to 5.75 m.s-1 at 5000 m. Comparable female speeds are 5.60 and 4.67 m.s-1, which are similar to male-female differences in running records. Analysis of variance of wheelchair finalists' average speeds indicated a significant (P less than 0.05) difference between the sexes, distances, and classes of athletes. Females were slower than males and tetraplegics slower than paraplegics over all distances. Tetraplegics did not show any significant change in speed over distance. Significant linear and quadratic trends over distance were noted for male paraplegics due to a generally decreasing speed with duration of the race and a peak speed at 200 m, respectively. Male paraplegics had a faster speed in the marathon compared to their longest track event, reflecting the greater speeds attainable during downhill wheeling.

Female↗

PubMed1987

Aerobic and anaerobic power of Canadian wheelchair track athletes.

The aerobic and anaerobic capabilities of six wheelchair track athletes were determined on a wheelchair ergometer prior to their competition in the 7th World Wheelchair Games. The sample included two male tetraplegics, one female paraplegic, and three male paraplegics, each in different competitive classifications. The evaluation of the anaerobic capabilities of the athletes involved determination of the total work accomplished during a 30-s all-out effort and the peak power output (PO) during a 5-s interval of this test. Aerobic capability was determined as the peak oxygen uptake and associated PO over a 1-min time period during a continuous progressive intensity test to exhaustion. Peak oxygen uptakes ranged from 1.00 to 3.43 1 X min-1 (16.9 to 50.7 ml X kg-1 X min-1) and aerobic PO from 19 to 120 W. Peak anaerobic PO was 21 to 70% higher (31 to 148 W) than aerobic PO, and total work in 30 s ranged from 740 to 4345 J. The male paraplegics displayed the highest values while the class 1A tetraplegic had the lowest. These laboratory findings were in general agreement with the athletes' performances in their track events.

Adult↗

PubMed1986

Maximal work production following two levels of artificially induced metabolic alkalosis.

In order to determine the influence of two artificially induced alkalotic states on the ability to perform maximal exercise, six male subjects (mean age, 22.0 years; mean height, 176.8 cm; mean weight, 69.1 kg; mean VO2 max, 3.83 l min-1) were studied during three experimental trials. The subjects performed six 60-s cycling bouts, at a work rate corresponding to 125% VO2 max, with 60 s recovery between work bouts; these regimens were performed 1 h after the ingestion of a solution containing either; I, placebo; II, NaHCO3 in a dosage of 0.15 g per kg body weight; or III, NaHCO3 0.30 g per kg body weight. The sixth work bout was continued until the pedal velocity dropped below 50 rev min-1. Total work done for the entire work period was calculated. Blood samples were taken from a forearm vein prior to the exercise bouts for analysis of pH and HCO3. The results showed a significant pre-exercise difference in pH and HCO3 for all conditions (P less than 0.01). In conditions where artificial alkalosis had been achieved prior to exercise there was significant increase in the work produced: I, 121.6 kJ; II, 133.1 kJ; III, 133.5 kJ (P less than 0.05). The time to fatigue in the six bout was also significantly increased; I, 74.7 s; II, 111.0 s; III, 106.0 p (P less than 0.05). There were no significant differences between conditions II and III. Thus augmentation of the bicarbonate reserves has a significant positive effect on the energy metabolism in interval-type exercise, leading to an increase in the work done and in the time to fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1985

Submaximal exercise responses of tetraplegics and paraplegics.

This study describes responses of 21 wheelchair users to a continuous, increasing work rate test to exhaustion on a wheelchair ergometer. Heart rate, ventilation, O2 uptake, respiratory exchange ratio, ventilation equivalent for O2, and O2 pulse were determined for each minute. Subjects were divided into tetraplegic (n = 8), high-lesion paraplegic (n = 6), and low-lesion paraplegic (n = 7) groups. Linear regression analyses, with O2 uptake as the independent variable, were used to determine the strength of relationships within each group and differences between groups in slopes and intercepts of regression equations. All variables were significantly (P less than 0.05) related to O2 uptake (r = 0.42-0.94). The only significant difference between the high- and low-lesion paraplegic groups was for heart rate intercept, as the heart rate for the low-lesion group tended to be lower at any given O2 uptake. Tetraplegics had a higher intercept and/or slope for ventilation equivalent, ventilation, and respiratory exchange ratio and lower intercepts for heart rate and O2 pulse. These differences in responses to a progressive exercise task are logically related to the differences in maximal O2 uptake, functional muscle mass, and vasomotor and cardiac control of the groups.

Exercise Test↗