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Biomedical subjects

R J Robertson

Publications and source records attributed to R J Robertson.

At least 19 recordsLinked to original sources
PubMed1992

Primary malignant localized fibrous tumours of the pleura: clinical, radiological and pathological features.

Localized fibrous tumours of the pleura are rare primary pleural tumours that may exhibit malignant behaviour in approximately 20% of cases. The clinical, radiological and pathological features of five patients with malignant localized fibrous tumours of the pleura are presented. Clinical symptoms included chest pain, breathlessness and cough. Hypertrophic pulmonary osteoarthropathy (HPOA) occurred in one patient. Chest radiographs and thoracic computed tomography (CT) demonstrated large necrotic masses, with focal calcification and compressive atelectasis of the underlying lung. Histological features were variable and resulted in designation of these tumours as localized fibrous tumours of the pleura of low or high grade malignancy. The grading of malignancy did not correlate with final outcome, adequacy of surgical excision being the most important factor. These tumours have been referred to as benign pleural fibromas or localized mesotheliomas, but these names are inaccurate and the term localized fibrous tumour of the pleura is to be preferred. This term should also include tumours such as malignant fibrous histiocytoma of the pleura.

Aged↗
PubMed1992

The validity of regulating exercise intensity by ratings of perceived exertion.

The purpose of this investigation was to examine the regulation of exercise intensity by using Ratings of Perceived Exertion (RPE). The RPE equivalent to 50% and 70% VO2max was estimated by using standard clinical protocols on a treadmill and cycle ergometer. Subjects then produced the target RPEs on these modalities. Physiological validity of perceptually regulated exercise intensity was determined by comparing VO2 and heart rate between estimation and production trials at the same relative intensity. With one exception, RPE was found to be a valid means of regulating exercise intensity both intra- and intermodally at 50% and 70% VO2max. Perceptual regulation of intramodal treadmill exercise was not valid at 70% VO2max in that both VO2 and heart rate were significantly lower during production than estimation. The present results also indicate that target RPE estimated during a cycle ergometer graded exercise test is more accurate for regulating exercise intensity than when the target RPE is estimated during a treadmill test. The lower accuracy found for treadmill production at the higher exercise intensity may have been caused by the use of a test protocol during the estimation trial that included relatively slow speeds and large inclines. In general, RPE provide a physiologically valid method of regulating exercise intensity.

Adolescent↗
PubMed1992

Abatement of exertional perceptions following dynamic exercise: physiological mediators.

Perceptual and physiological congruity was examined during recovery from high-intensity dynamic exercise. Nine males (24.8 +/- 0.6 yr; VO2max; 52.3 +/- 1.5 ml.kg-1.min-1) undertook in random order four maximal treadmill protocols. Treadmill speed was held constant (5.3 km.h-1) while grade was incremented by 2, 4, 6, or 8% every 3 min for protocols A, B, C, and D, respectively. Ratings of perceived exertion (RPErec; Borg 15-point scale), ventilation (VE), respiratory rate (RR), oxygen uptake (VO2), and heart rate (HR) were measured preexercise and during each min of a 12-min supine postexercise period that immediately followed treadmill testing. Ratings were obtained for the peripheral perceptual signal arising from the legs (RPErec-L), the respiratory-metabolic signal from the chest (RPErec-C), and the overall body signal (RPErec-O). Blood pH was measured preexercise and during min 1, 6, and 12 of recovery. RPErec-L and RPErec-O were lower (P less than 0.05) and blood pH higher (p less than 0.05) following protocol A than D at all recovery time points. RPErec-C, VE, and RR were lower (P less than 0.05) for protocol A than D at all recovery time points. Differences among protocols were not noted for VO2 or HR at any recovery time point. The decay in signal strength for both RPErec-L and RPErec-O following high-intensity exercise reflected the abatement of metabolic acidosis. RPErec-O was influenced by the abatement of pulmonary ventilation during the postexercise period.

Acidosis↗
PubMed1991

The radiology of Askin tumours.

The Askin tumour is a highly malignant primitive neuroectodermal tumour (PNET) of the chest wall occurring in children and young adults. We describe three cases to illustrate the clinical and radiological aspects of this tumour, which are not well documented. Patients present with a chest wall mass, pain and constitutional symptoms. Radiology demonstrates a large soft tissue chest wall mass, local rib erosion and pleural effusion. Recurrence tends to be local chest wall, pulmonary or skeletal. The prognosis is poor. Askin tumours must be considered in the differential diagnosis of chest wall masses in children and young adults.

Bone and Bones↗
PubMed1991

Physiological and thermal responses of males with varying body compositions during immersion in moderately cold water.

The effect of body composition on the thermal and metabolic responses of 24 male volunteers (20 to 35 years) was examined during 90 min of moderately cold (18, 22, or 26 degrees C) water immersion to the first thoracic vertebrae. Body composition was determined via underwater densitometry. Subjects were divided with respect to body fat (high fat (HF) = 18-22%, n = 12; Low fat (LF) = 8-12%, n = 12) and randomly assigned to one of three water temperatures. Rectal temperature (degree C) after 90 min of immersion did not differ in LF and HF at 18 degrees C (35.9 vs. 36.2), 22 degrees C (36.0 vs. 36.0), and 26 degrees C (36.0 vs. 36.3). Oxygen uptake (VO2, ml-kg-1.min-1) was greater in LF than in HF in all water temperatures. Oxygen uptake at 90 min was greater for LF than HF in 18 degrees C (11.48 vs. 9.19), 22 degrees C (9.79 vs. 4.70), and 26 degrees C (6.21 vs. 5.44). Mean skin temperature in LF and HF approached water temperature within the first 5 min. Despite the thermal strain of cold water immersion, the LF subjects were able to maintain a similar Tre compared to the HF due to a significantly greater shivering thermogenesis.

Adipose Tissue↗
PubMed1991

RPE, blood glucose, and carbohydrate oxidation during exercise: effects of glucose feedings.

This study examined the effects of glucose ingestion on differentiated and undifferentiated ratings of perceived exertion (RPE) during prolonged cycling exercise. On two occasions, seven trained males cycled for 180 min on a Monark cycle ergometer at 70% peak VO2 (VO2peak). Subjects consumed an 8% glucose/electrolyte drink (G) or a flavored water placebo (P) every 15 min throughout exercise. Measurement of RPE, ventilation (VE), oxygen uptake (VO2), respiration rate (RR), respiratory exchange ratio (RER), heart rate (HR), and venous blood sample collection preceded ingestion of the drink. Subjects were homogenous with respect to height, weight, and VO2peak. RPE for the legs and overall body were significantly attenuated (P less than 0.05) during the last 45 min of exercise. Plasma glucose and insulin were higher (P less than 0.05) in G than in P at virtually all time points. CHO oxidation and work rate were maintained throughout exercise in G but not during the last 30 min of exercise in P (P less than 0.05). Percent changes in plasma volume, plasma lactate, HR, VE, RR, and RPE for the chest were not different between conditions (P greater than 0.05). The data suggest that ingestion of carbohydrate beverages during endurance cycling can maintain plasma glucose and CHO oxidation during the latter stages of prolonged exercise. As a result, it appears that a relationship exists between attenuation of ratings of perceived exertion (especially in the legs), blood glucose, and CHO oxidation late in prolonged exercise. The mechanism for this probably involves the increased availability of blood-borne glucose to serve as substrate for brain and/or muscle energy metabolism during a time when endogenous stores of carbohydrate are low.

Analysis of Variance↗
PubMed1990

Blood glucose extraction as a mediator of perceived exertion during prolonged exercise.

The effect of blood glucose extraction on the perception of exertion was examined during prolonged arm exercise. Eight male subjects consumed in counter-balanced order a standard daily diet containing either (1) 75 g dihydroxyacetone and 25 g sodium pyruvate (DHAP) or (2) an isocaloric amount of placebo, to manipulate blood glucose extraction. Following each 7-day diet, subjects exercised to exhaustion at 60% of peak arm oxygen consumption. Ratings of perceived exertion (Borg, CR-10 scale) were obtained for the arms (RPE-A), legs (RPE-L), chest (RPE-C) and overall body (RPE-O) every 10 min of exercise. After 60 min of continuous exercise, blood samples were drawn from the radial artery and axillary vein. Ratings of perceived exertion did not differ between trials during the first 50 min of exercise. At the 60-min time point, perceived exertion was lower (P less than 0.01) in the DHAP than placebo trials for the arms (RPE-A: 4.25 vs 5.50) and overall body (RPE-O: 3.25 vs 4.00). These differences persisted throughout exercise. RPE-L and RPE-C did not differ between trials. Whole-arm arterial-venous glucose difference was higher (P less than 0.05) in the DHAP (1.00 mmol.l-1) than placebo (0.36 mmol.l-1) trials, as was fractional extraction of glucose (22.5 vs 9.0%). Respiratory exchange ratio was the same between trials. Triceps muscle glycogen was (1) higher in the DHAP than placebo trial at pre-exercise (P less than 0.05), (2) decreased during exercise and (3) did not differ between trials at exercise termination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Enhancement of arm exercise endurance capacity with dihydroxyacetone and pyruvate.

The effects of dietary supplementation of dihydroxyacetone and pyruvate (DHAP) on endurance capacity and metabolic responses during arm exercise were determined in 10 untrained males (20-26 yr). Subjects performed arm ergometer exercise (60% peak O2 consumption) to exhaustion after consumption of standard diets (55% carbohydrate, 15% protein, 30% fat; 35 kcal/kg) containing either 100 g of Polycose (placebo, P) or DHAP (3:1, treatment) substituted for a portion of carbohydrate. The two diets were administered in a random order, and each was consumed for a 7-day period. Biopsy of the triceps muscle was obtained immediately before and after exercise. Blood samples were drawn through radial artery and axillary vein catheters at rest, after 60 min of exercise, and at exercise termination. Arm endurance was 133 +/- 20 min after P and 160 +/- 22 min after DHAP (P less than 0.01). Triceps glycogen at rest was 88 +/- 8 (P) and 130 +/- 19 mmol/kg (DHAP) (P less than 0.05). Whole arm arteriovenous glucose difference (mmol/l) was greater (P less than 0.05) for DHAP than P at rest (0.60 +/- 0.12 vs. 0.05 +/- 0.09) and after 60 min of exercise (1.00 +/- 0.12 vs. 0.36 +/- 0.11), but it did not differ at exhaustion. Neither respiratory exchange ratio nor respiratory quotient differed between trials at rest, after 60 min of exercise, or at exhaustion. Plasma free fatty acid, glycerol, beta-hydroxybutyrate, catecholamines, and insulin were similar during rest and exercise for both diets. Feeding DHAP for 7 days increased arm muscle glucose extraction before and during exercise, thereby enhancing submaximal arm endurance capacity.

Adult↗
PubMed1990

Enhanced leg exercise endurance with a high-carbohydrate diet and dihydroxyacetone and pyruvate.

The effects of dietary supplementation of dihydroxyacetone and pyruvate (DHAP) on metabolic responses and endurance capacity during leg exercise were determined in eight untrained males (20-30 yr). During the 7 days before exercise, a high-carbohydrate diet was consumed (70% carbohydrate, 18% protein, 12% fat; 35 kcal/kg body weight). One hundred grams of either Polycose (placebo) or dihydroxyacetone and pyruvate (treatment, 3:1) were substituted for a portion of carbohydrate. Dietary conditions were randomized, and subjects consumed each diet separated by 7-14 days. After each diet, cycle ergometer exercise (70% of peak oxygen consumption) was performed to exhaustion. Biopsy of the vastus lateralis muscle was obtained before and after exercise. Blood samples were drawn through radial artery and femoral vein catheters at rest, after 30 min of exercise, and at exercise termination. Leg endurance was 66 +/- 4 and 79 +/- 2 min after placebo and DHAP, respectively (P less than 0.01). Muscle glycogen at rest and exhaustion did not differ between diets. Whole leg arteriovenous glucose difference was greater (P less than 0.05) for DHAP than for placebo at rest (0.36 +/- 0.05 vs. 0.19 +/- 0.07 mM) and after 30 min of exercise (1.06 +/- 0.14 vs. 0.65 +/- 0.10 mM) but did not differ at exhaustion. Plasma free fatty acids, glycerol, and beta-hydroxybutyrate were similar during rest and exercise for both diets. Estimated total glucose oxidation during exercise was 165 +/- 17 and 203 +/- 15 g after placebo and DHAP, respectively (P less than 0.05). It is concluded that feeding of DHAP for 7 days in conjunction with a high carbohydrate diet enhances leg exercise endurance capacity by increasing glucose extraction by muscle.

Adult↗
PubMed1990

Cross-modal exercise prescription at absolute and relative oxygen uptake using perceived exertion.

Cross-modal exercise prescription at absolute and relative oxygen uptake using perceived exertion. Med. Sci. Sports Exerc., Vol. 22, No. 5, pp. 653-659, 1990. The validity of cross-modal prescription of exercise intensity based on rated perceived exertion (RPE) was determined for eight men (26 +/- SE 1.9 yr) at absolute and relative VO2. Exercise modes were treadmill (TM), cycle ergometer (C), and bench stepping while pumping 0.91 kg handweights (HB). Relative (Rel) constant load sessions were performed for each mode at 70% of mode-specific VO2 peak. Absolute (Absol) constant load sessions were performed for C and HB at the VO2 equivalent to 70% of TM VO2 peak. The five 12 min sessions were presented on separate days in random order. RPE-Overall during TM-Rel (11.1) was a) lower (P less than 0.05) than C-Absol (12.6) and HB-Absol (12.5) and b) the same as C-Rel (11.3) and HB-Rel (10.7). RPE-Legs during TM-Rel was a) lower (P less than 0.05) than C-Absol and HB-Absol and b) the same as C-Rel and HB-Rel. RPE-Chest a) did not differ between TM-Rel and C-Absol or HB-Absol and b) was lower (P less than 0.05) for C-Rel and HB-Rel than TM-Rel. RPE-Arms was higher (P less than 0.05) for C-Absol, HB-Absol, and HB-Rel than TM-Rel but did not differ between TM-Rel and C-Rel. Oxygen uptake, heart rate, and ventilation during TM-Rel were a) the same as C-Absol and HB-Absol and b) higher (P less than 0.05) than C-Rel and HB-Rel. Perceptually based cross-modal prescription of exercise intensity using a psychophysical estimation method is valid provided that the physiological reference is the relative, not the absolute, VO2.

Adult↗
PubMed1989

Aerobic metabolic requirements of simulated cross-country skiing.

This study evaluated the aerobic metabolic requirements of simulated cross-country skiing. Five male subjects exercised on a cross-country skiing machine at 12 different arm and leg resistances and movement frequencies. Oxygen consumption (VO2) ranged from 21.6 to 44.4 ml kg(-1) min(-1). The VO2 increased significantly (p less than 0.05) as the frequency of limb movement was increased. These data suggest that simulated cross-country skiing places a significant demand on the aerobic metabolic system and as such is a viable alternative to conventional cardiovascular exercise modalities.

Adult↗
PubMed1989

Energy cost of bench stepping and pumping light handweights in trained subjects.

Rhythmic pumping of light hand-held weights while walking or running has become a popular approach to total body aerobic exercise. The use of handweights (HW) in conjunction with walking and running significantly increases the energy requirement of a given locomotor speed and adds variety to the choice of modes when prescribing exercise regimens (Auble, Schwartz, & Robertson, 1987; Francis & Hoobler, 1986; Graves, Pollock, Montain, Jackson, & O'Keefe, 1987). Handweighted exercise can also be conveniently and accurately prescribed for use with other exercise modalities such as bench stepping (Goss, et al., 1987). Stepping up and down on a bench at varying frequencies while pumping handweights is a low-impact, space efficient form of total body aerobic exercise. However, little is known about the energy cost of this unique exercise modality. Such information is important if handweighted exercise is to be used in conjunction with bench stepping when prescribing both therapeutic and recreational training regimens. The purpose of this investigation, therefore, was to evaluate the energy cost associated with combined bench stepping and rhythmic pumping of light handheld weights.

Adult↗
PubMed1989

Effect of induced alkalosis on perception of exertion during intermittent exercise.

The purpose of this study was to evaluate the effects of metabolic alkalosis on differentiated ratings of perceived exertion during intermittent high-intensity exercise. Six endurance-trained females participated as subjects in this investigation. Each subject underwent three separate experimental trials in which NaHCO3 was ingested in either a single (0.3 g NaHCO3/kg body wt) or periodic schedule (0.12 g NaHCO3/kg body wt initially, with 0.18 g/kg body wt distributed in equal doses before each 5-min exercise bout). Calcium carbonate served as a placebo control. An intermittent exercise protocol was used in which each subject rode a cycle ergometer at 90% maximum O2 consumption for 5 min. Within each acid-base condition, the exercise protocol was repeated three times with 10-min rest periods interspersed. Differentiated ratings of perceived exertion for the legs (RPE-L), chest (RPE-C), and overall body (RPE-O) were attenuated under alkalotic treatment relative to placebo control regardless of pattern of NaHCO3 administration. RPE-L, RPE-C, and RPE-O were negatively correlated to the bicarbonate concentration of venous blood. This investigation suggests that perception of effort during high-intensity intermittent exercise can be related to buffering capacity of the blood.

Acid-Base Equilibrium↗
PubMed1989

Effect of life-style activity of varying duration on glycemic control in type II diabetic women.

Life-style activities such as walking are often recommended for patients with type II (non-insulin-dependent) diabetes. Because many of these patients are overweight and sedentary, such low-intensity activity would appear most appropriate, especially during initial intervention. However, there has been little research on the effects of low-intensity life-style activity on glycemic control. This study examined the effects of varying the duration (0, 20, or 40 min) of low-intensity exercise (50-55% of age-predicted max heart rate) on glycemic responses during exercise and a subsequent meal in type II diabetic patients. Glycemic response to exercise was significantly related to the duration of activity; 20 min of activity decreased blood glucose (BG) by 6 mg/dl, whereas 40 min decreased BG by 16 mg/dl. The effect of exercise on glucose was maintained over a 30-min rest period but disappeared after a meal was consumed. Insulin and the insulin-to-glucose ratio were not affected by the length of activity. These data suggest that life-style activity of long duration (20-40 min) produces a significant, but modest, decrease in glucose levels in type II diabetic women.

Blood Glucose↗
PubMed1988

Effect of simulated altitude erythrocythemia in women on hemoglobin flow rate during exercise.

The effect of simulated altitude erythrocythemia on hemoglobin flow rate and maximal O2 uptake (VO2max) was determined for nine women sea-level residents. Test conditions included normoxia and normobaric hypoxia (16% O2-84% N2). Cycle tests were performed under normoxia (T1-N) and hypoxia (T1-H) at prereinfusion control and under hypoxia 48 h after a placebo infusion (T2-H) and 48 h after autologous infusion of 334 ml of erythrocytes (T3-H). Hematocrit (38.1-44.9%) and hemoglobin concentration (12.7-14.7 g.dl-1) increased from control to postreinfusion. At peak exercise, VO2max decreased from T1-N (2.40 l.min-1) to T1-H (2.15 l.min-1) then increased at T3-H (2.37 l.min-1). Maximal arterial-mixed venous O2 difference decreased from T1-N to T1-H and increased at T3-H. Cardiac output (Q), stroke volume, heart rate, and total peripheral resistance during maximal exercise were unchanged from T1-N through T3-H. Hemoglobin flow rate (Hb flow) at maximum did not change from T1-N to T1-H but increased at T3-H. When compared with submaximal values for T1-N, VO2 was unchanged at T1-H and T3-H; Q increased at T1-H and decreased at T3-H; arterial-mixed venous O2 difference decreased at T1-H and increased at T3-H; Hb flow did not change at T1-N but increased at T3-H. For young women, simulated altitude erythrocythemia increased peak Hb flow and decreased physiological altitude (227.8 m) but did not affect maximum cardiac output (Qmax).

Adult↗
PubMed1987

The effect of acute exercise on high density lipoprotein-cholesterol and the subfractions in females.

The effect of an acute exercise session on high density lipoprotein-cholesterol (HDL-C) and the subfractions HDL2-C and HDL3-C was determined for 9 healthy females (VO2max = 46.62 +/- 4.82 ml X kg-1 min-1). Each subject underwent a continuous 40-min run on a treadmill at a workload corresponding to 70% of VO2max. A venous blood sample was obtained immediately prior to exercise and 5 min, 24, 48 and 96 h after the exercise. Pre-exercise values were: HDL-C (61.7 +/- 3.7 mg X dl-1); HDL2-C (22.4 +/- 2.1 mg X dl-1); HDL3-C (39.3 +/- 2.0 mg X dl-1). At 5 min after exercise, HDL-C (66.2 +/- 4.4 mg X dl-1) and HDL3-C (44.5 +/- 2.8 mg X dl-1) were significantly elevated (P less than 0.01) when compared to pre-exercise values. HDL-C and HDL3-C were not significantly different from pre-exercise at the remaining time points. In comparison with pre-exercise, HDL2-C showed no significant change at any of the post-exercise time points. Results indicated that the rise in HDL-C following acute exercise was due to an increase in the subfraction HDL3-C. The change in total HDL-C and HDL3-C was transient in that pre-exercise values were re-attained within 24 h following acute submaximal exercise.

Adult↗