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Biomedical subjects

G C Gass

Publications and source records attributed to G C Gass.

31 records · Page 2Linked to original sources
PubMed1984

The maximum physiological responses during incremental wheelchair and arm cranking exercise in male paraplegics.

Ten physically active male paraplegics (means = 30 +/- 1 yr), with lesion levels ranging from T5 to L4/S2, underwent two incremental exercise tests to exhaustion. The exercise tests were arm cranking, utilizing an electronically-braked arm cranker, and wheelchair propulsion on a motor-driven treadmill. The subjects were randomly assigned to groups, and the exercise tests were separated by 1 wk. For the first six subjects, during both modes of exercise, VO2, VCO2, R, VE, and heart rates were recorded throughout; for the remaining four subjects the same variables were recorded after the heart rate reached 160 b X min-1. The VO2 (l X min-1 and ml X min-1 X kg-1), VCO2 (l X min-1), HR, and VE BTPS (l X min-1) were significantly higher at the termination of the wheelchair exercise than at the termination of the arm cranking exercise. The minute ventilation, when recorded throughout both exercise tests, showed a relatively linear phase at first, followed by a curvilinear phase. The findings of this study indicate that in the present group of paraplegics, the highest VO2 was obtained during maximum wheelchair exercise.

Adult↗
PubMed1983

Anaerobic threshold and lactate turnpoint.

Venous lactate concentration and ventilatory responses to progressively increased work rates were studied in 16 men who performed an incremental exercise test to exhaustion on an electrically braked cycle ergometer. In this test the characteristic curvilinear increase in venous lactate concentrations was observed. In addition to the anaerobic threshold (AT), a second breakpoint was observed and named the lactate turnpoint (LTP). Eight of the 16 subjects performed a second incremental exercise test initiated during lactic acidosis. In this test the direction of change in venous lactate concentrations was different. The work rate at which lactate concentrations again increased, after a steady decline (previously described as the AT2), was similar to the work rate established for the LTP in the first test. In the second test removal of lactate was demonstrated at work rates exceeding the AT. Although the lactate response to the two tests was different the pattern of change was similar, with the two breakpoints occurring at the same work rates. Collectively these results lend a measure of support to the hypothesis of a positive relationship between the AT, LTP, and a pattern of recruitment of motor units with different enzyme profiles. Both the AT and LTP were predictable from the ventilatory response to incremental exercise.

Acidosis↗
PubMed1983

Prolonged exercise in highly trained female endurance runners.

The effects of prolonged exercise in a 21 degree C dry bulb and 15 degree C wet bulb environment at 65%-70% VO2max were examined in seven highly trained females. The subjects, aged 22-35 years, underwent an initial incremental treadmill test to exhaustion, with assessment of VO2max and related cardiorespiratory variables. One week later, under similar environmental conditions, subjects ran at approximately 65% VO2max for 80 min on a motor-driven treadmill. Approximately 10 ml of venous blood was withdrawn 10 min prior and immediately prior to the onset of prolonged exercise, and at 20, 40, 60, and 80 min, and 20 min post-exercise. Venous blood was analyzed for glucose, lactate, osmolality, Na+, K+, protein, and hemoglobin (Hb). Hematocrit was measured and changes in plasma volume calculated. VO2, VE, respiratory exchange ratio, and heart rate were recorded at 17, 37, and 77 min. The percent body fat estimated from skinfold thicknesses was 19 +/- 1%. The mean VO2max was 59.3 +/- 1.0 ml . kg-1 . min-1, with a mean max VE STPD and heart rate of 78.75 +/- 3.10 1 . min-1 and 175 +/- 4 beats . min-1, respectively. No significant changes occurred in VO2, VE, % VO2max, heart rate, venous lactate, plasma glucose, or plasma protein during the prolonged exercise. A significant decrease in respiratory exchange ratio was noted. Significant changes also occurred in hematocrit, Hb, Na+, K+, and osmolality. An interesting finding was the pre-exercise expansion of the plasma volume.

Adipose Tissue↗
PubMed1981

Oxygen deficit during incremental exercise.

The oxygen deficit and debt have conventionally been determined during exercise at constant work rates. During this study these were calculated during and after exercise at progressively incremented work rates. Five men performed two successive incremental exercise tests to exhaustion on an electronically braked cycle ergometer. The two tests were separated by a 5 min rest period. The oxygen deficit was defined as the sum of the minute differences between the measured oxygen uptake and the oxygen uptake occurring during steady state work at that same rate. The oxygen deficit was quantified for the work periods before and after the anaerobic threshold (AT) as determined from respiratory gas analysis (ATR). The measured deficit for the period before the ATR was smaller than the deficit measured in the same subjects during steady state work at low intensity (below the ATR) and was also less than the rapid component of the oxygen repayment as determined after the second incremental test. It was concluded that this test could be used for the determination of anaerobic capacity as represented by the total oxygen deficit (within motivational limits), but that the lactacid and alactacid components of the deficit could not be differentiated. A considerable portion of the alactacid component of the deficit was incurred after the onset of the ATR.

Adolescent↗
PubMed1981

Serum cortisol response to incremental work in experienced and naive subjects.

Twelve experienced and seven naive male subjects with a similar Vo2max, performed an incremental work test on an electronically braked bicycle until exhaustion. High venous lactate concentrations were recorded in both groups (naive-11.74 +/- 2.43, experienced-13.96 +/- 2.36 mmol/liter). No significant relationship could be demonstrated between Vo2max, venous lactate concentration, Borg ratings of perceived exertion, and the serum cortisol response. The postexercise increase in serum cortisol was significant in both experienced (59%) and naive (138%) groups, and was significantly greater in the naive as compared to the experienced subjects. The present results indicate that the psychoendocrine response to a novel situation was a major determinant of the serum cortisol response to maximum work.

Humans↗
PubMed1981

Blood lactate concentration following maximum exercise in trained subjects.

The time when blood lactate reaches peak concentration following maximum exercise is unclear. The post exercise venous blood lactate concentration was determined serially for 30 minutes in 13 trained men following maximum exercise on a motor driven treadmill. Lactates were determined enzymatically in duplicate. The VO2 max and percent body fat was 65.1 +/- 4.8 ml.kg-1.min-1 and 11.4 +/- 1.4, respectively. The venous lactate reached a peak concentration at the 6th minute (14.2 mmol.L-1) of an inactive recovery, and declined linearly thereafter to reach a concentration of 7.43 +/- 0.60 mmol.L-1 at the 30th minute. The net rate of lactate removal was .30 mmol.L-1.min-1. Statistical analysis found no significant difference in lactate concentration during the 4th, 5th and 6th minute post exercise, indicating that these post exercise times may be appropriate to sample venous blood for peak lactate concentration.

Adult↗
PubMed1981

The effects of prolonged exercise on spinally injured subjects.

The effects of prolonged exercise on paraplegics have not been reported. Seven male paraplegic subjects with spinal lesions from T4 - T12 - L1 underwent an incremental wheelchair treadmill test to exhaustion. Heart rate (HR), VO2max, and VESTPD were recorded and calculated. One week later, subjects exercised in their wheelchairs at approximately 50% (mean = 52 +/- 2%) of VO2max for 60 min on a motorized treadmill. Approximately 10 ml venous blood was withdrawn both 10 min and immediately prior to the prolonged exercise, at 20, 40, and 60 min of the exercise period, and at 10 min post-exercise. Venous blood was analyzed for glucose, hemoglobin, lactate, Na+, K+, Cl-, and plasma protein. Hematocrit was recorded and plasma volume changes calculated VO2, VE, and HR were recorded at 17, 37, and 57 min of the prolonged exercise. The mean VO2max was 29.5 +/- 2.7 ml.kg-1.min-1, with a mean max VESTPD and HR of 61.86 +/- 4.98 1.min-1 and 174 +/- 4 b.min-1, respectively. The changes in VO2 and VE during the prolonged wheelchair exercise were not significant. Significant changes occurred in venous lactate and plasma glucose concentrations during prolonged wheelchair exercise. Plasma volume changes were similar to those seen in able-bodied subjects. A notable finding was the pre-exercise hemodilution. Present data indicate that paraplegics can exercise at approximately 50% VO2 for 60 min, producing responses similar to those in able-bodied subjects.

Adult↗
PubMed1980

The effects of physical training on high level spinal lesion patients.

Seven chronically institutionalised high level spinal lesion subjects participated in an exercise program, five days per week for seven weeks. Anthropometry, spirometry and maximum oxygen consumption (VO2 max) was measured initially and at the end of seven weeks. Subjects generally followed a common training program. No significant changes were noted in the anthropometric and spirometric measurements. A significant increase (34%) in minute ventilation was recorded, and this was accompanied by significant increases in VO2 max 0.764 +/- 0.341 to 1.03 +/- 0.419 1 x min-1 (P less than 0.01) and wheelchair treadmill time 502 +/- 340 to 766 +/- 249 sec (P less than 0.05). The exercise program had no significant effect on maximum or recovery heart rates. Many subjects had subjective comments on improved psychological state. The significant changes in VV2 max, VE, and wheelchair treadmill time indicated that high level spinal lesion subjects can exhibit an improved cardiovascular function through regular aerobic exercise.

Adult↗
PubMed1979

Blood lactate concentrations during incremental work before and after maximum exercise.

Five male subjects performed three successive incremental work tests on an electronically braked cycle ergometer. The first and second tests were separated by thirty minutes of rest, the second and third by three minutes of maximum work. During the third test, venous blood lactate concentrations were still decreasing at work rates where they were increasing during the first two tests. The work rate at which rapid increases in lactate concentrations occurred during the final test coincided with the work rate where rapid increases occurred in the two initial tests. It was concluded that this point represented a threshold where a balance existed between removal and release of lactate from and into the plasma compartment, and did not coincide with the anaerobic threshold. It is postulated that steady state work at levels above this threshold would result in a continuous increase in venous lactate concentration.

Adult↗
PubMed1979

Oxygen concumtpion and biochemistry of Australian women physiotherapists.

Oxygen consumption and related spirometric, biochemical, and anthropometric variables were measured in 28 practicing Australian women physiotherapists at 3 teaching hospitals. Heart rate while on ward duty was also measured in 2 randomly selected physiotherapists. The majority of measurements were found to be within normal limits for Australian women and consistent with women of similar age in occupational groups in other countries, except for body fat, which was lower, and maximum oxygen consumption, which was higher. The later exceptions are believed to be the result of the physical work required of Australian women physiotherapists.

Adipose Tissue↗
PubMed1979

Physiological characteristics of trained Australian paraplegic and tetraplegic subjects.

Sixteen male Australian paraplegic and tetraplegic subjects competing at the 1977 FESPIC games underwent a physiological assessment. The assessment included a neurological examination, anthropometry, spirometry, maximum oxygen consumption using a wheelchair and motor driven treadmill and a 5 minute post exercise blood lactate. Eight subjects had won gold medals at international competitions for the disabled, and, at the time of testing, two of the subjects were world record holders in track and field events. Spirometry was consistent with other reported values with FVC and FEV1.0 being 4.94 and 4.25 l respectively. The cardiorespiratory data revealed a mean VO2max 2.04+/-0.64 l min-1, and 33.0+/-9.4 ml kg-1 min-1; VE STPD, 60.75+/-22.64 l min-1; maximum heart rate 179+/-20 b min-1 and post exercise lactate 11.73+/-1.94 mM. It was concluded that many physiological variables measured on the Australian subjects at rest and during maximum work were comparable to other trained disabled athletes.

Anthropometry↗