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Biomedical subjects

F J Nagle

Publications and source records attributed to F J Nagle.

At least 37 records · Page 2Linked to original sources
PubMed1985

Aerobic requirements of overground versus treadmill running.

There is general agreement that the oxygen demand of level running is similar for both the treadmill (TM) and overground situations at speeds under 260 m X min-1. However, controversy exists with regard to inclined running. The prevailing view, represented by the ACSM prediction formulas, is that overground hill running is theoretically more costly than inclined treadmill running. This study was designed to investigate the problem from an empirical standpoint. Seven male subjects performed overground and TM running at two grades (0 and 5.7%) over a range of speeds between 136-286 m X min-1. For the outdoor trials, subjects covered a distance of 950 m at a constant pace, and expired gas was collected over the last 150 m. Matching trials were then performed on the treadmill at the same speed and % grade. Regression lines were calculated for speed vs oxygen consumption (VO2). For TM and overground level running, these were: VO2 (ml.kg-1.min-1)= 0.222 X speed (m.min-1) - 1.33 and VO2 (ml.kg-1.min-1) = 0.202 X speed (m.min-1) + 3.21 respectively. The regression lines from TM and overground inclined running were: VO2 (ml.kg-1.min-1) = 0.237 X speed (m.min-1) + 7.53. and VO2 (ml.kg-1.min-1) = 0.233 X speed (m.min-1) + 7.78 respectively. A 2 X 3 X 2 ANOVA revealed that the differences between mean values for VO2 for level TM running vs level overground running and grade TM running vs grade overground running were not statistically significant (0.10 less than P less than 0.25).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Changes in rate-pressure product with physical training of individuals with coronary artery disease.

The purpose of this study was to evaluate the effect of two factors--progression of coronary artery disease and physical training of individuals with coronary artery disease--on rate-pressure product (RPP). Subjects received a resting ECG and exercise test using the Balke protocol. We established three groups, one Experimental (E, n = 71) and two Control (C-1, n = 26; C-2, n = 24). Subjects in Groups E and C-1 had initial tests confirming coronary artery disease; subjects in Group C-2 had initial tests within normal limits. Subjects in Group E received treatment consisting of regular aerobic exercise with controlled intensity, frequency, and duration. Subjects in Groups C-1 and C-2 received no regular exercise. After a 10- to 12-month period, all subjects received a second resting ECG and exercise test using the Balke protocol. Changes in estimated maximal aerobic capacity (Vo2max), maximal RPP, and submaximal RPP from initial to final tests were analyzed for all groups. Descriptive statistics were done. The lack of significant changes in estimated Vo2max or in RPP in the Control Groups indicated no effect of progression of the disease or testing procedure familiarity. The estimated Vo2max for Group E increased significantly (p less than .01). Rate-pressure product increased significantly (p less than .01) in maximal exercise and decreased significantly (p less than .01) in submaximal exercise. This finding suggests that physiological changes both in exercising skeletal muscle and the myocardium play a role in the symptomatic improvements and increased maximal work capacities in individuals with coronary artery disease after regular aerobic exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1984

VO2max responses in separate and combined arm and leg air-braked ergometer exercise.

Using an air-braked cycle ergometer, we sought to determine the relative contributions of the arms and legs in eliciting the maximal O2 uptake (VO2max). Ten healthy, non-arm-trained males did progressive exercise to exhaustion on the ergometer instrumented to partition the push-pull arm exercise from the cycling leg exercise. Exercise was done with arms only (100% arms), legs only (100% legs, with arms at sides), and in combinations of 10% arms/90% legs, 20% arms/80% legs, and 30% arms/70% legs. To approximate conventional bicycling, four subjects exercised to exhaustion doing leg cycling on the air-braked ergometer with the hands fixed to stationary bars. The maximal power output and VO2max were not significantly different (P greater than 0.05) for the 10% arms/90% legs and the 20% arms/80% legs combinations. Maximal power output and VO2max for 10% arms/90% legs was significantly greater than that for the 100% arms, 100% legs, and 30% arms/70% legs regimens (P less than 0.05). The highest VO2max measured in combined arm/leg exercise for four subjects using 10% arms/90% legs (N = 3) or 20% arms/80% legs (N = 1) was not significantly different from that measured in air-braked ergometer leg cycling with hands fixed to stationary bars (P greater than 0.05). We conclude that push-pull arm exercise of 10 or 20%, combined with leg cycling of 90 or 80%, respectively, or leg cycling with hands fixed to bars optimize the arm/leg contributions in eliciting VO2max. These findings suggest that the upper-body stabilizing effort in conventional cycling (legs cycling, hands fixed) contributes approximately 10-20% to inducing VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Total cholesterol and HDL-cholesterol changes during acute, moderate-intensity exercise in men and women.

Chronic endurance exercise training has been associated with decreased levels of total cholesterol and increased HDL-cholesterol. To our knowledge rapid changes in cholesterol and HDL-cholesterol during acute exercise have not been described under controlled conditions. We studied 28 subjects (14 males and 14 females) during bicycle exercise for 40 min at a work intensity of 55% of their maximal oxygen consumption. Total and HDL-cholesterol levels were measured (and LDL-cholesterol calculated) at rest, 10, 20, 30, and 40 min of exercise, and 15 min postexercise. There was a significant (p less than 0.001) increase in HDL-cholesterol levels at 10 min of exercise (58.8 +/- 13.9 mg/dl, mean +/- SD) above rest (53.1 +/- 13.4 mg/dl) for all subjects. This increase persisted (p less than 0.001) at all time points throughout the exercise session, but declined by 15 min postexercise. There was a small, insignificant decline in LDL-cholesterol. It is concluded that apparent favorable changes in lipoprotein patterns occur acutely, and are sustained during short-term, moderate intensity exercise. Analyses of these changes appears necessary if the biochemical mechanisms which underlie these metabolic alterations are to be elucidated.

Adolescent↗
PubMed1983

Similarity of cardiovascular response to upper and lower body static contraction in endurance-trained and untrained males.

The purpose of this study was to investigate the cardiovascular response to upper and lower body static contraction in endurance-trained (ET) and untrained (UT) males (both groups N = 6). The groups were similar in age, height, and weight. However, the ET group exhibited a markedly higher (P less than 0.01) VO2 max during treadmill running than the UT group (65.4 +/- 4.8 vs 49.9 +/- 2.8 ml X kg-1 X min-1, mean +/- SD). Both groups performed static handgrip and leg extension in a randomly assigned order at 30% of maximal voluntary contraction for 3 min. Heart rate and mean intra-arterial blood pressure (MABP) were measured at rest and throughout contraction. At rest, differences between the two groups were not significant for heart rate (54 +/- 10 vs 66 +/- 8 beats X min-1) or MABP (93 +/- 4 vs 91 +/- 5 mm Hg). During handgrip, the increases in heart rate (24 +/- 12 vs 15 +/- 6) and MABP (24 +/- 10 vs 27 +/- 12) were not significantly different between the two groups. During leg extension, the magnitude of the increases in heart rate (44 +/- 21 vs 46 +/- 27) and MABP (37 +/- 11 vs 41 +/- 10) were again not different for the two groups. These results suggest that cardiovascular regulation during static contraction is similar in endurance-trained and untrained individuals, even during contraction involving the trained musculature.

Adult↗
PubMed1983

Increased cardiovascular response to static contraction of larger muscle groups.

The purpose of this study was to investigate the influence of the size of the active muscle mass on the cardiovascular response to static contraction. Twelve male subjects performed one-arm handgrip (HG), two-leg extension (LE), and a "dead-lift" maneuver (DL) in a randomly assigned order for 3 min at 30% of maximal voluntary contraction. O2 uptake (VO2), heart rate (HR), and mean intra-arterial blood pressure (MABP) were measured at rest and, in addition to absolute tension exerted, throughout contraction. There was a direct relationship between the size of the active muscle mass and the magnitude of the increases in VO2, HR, and MABP, even though all contractions were performed at the same relative intensity. Tension, VO2, HR, and MABP increased progressively from HG to LE to DL. It was concluded that at the same percentage of maximal voluntary contraction, the magnitude of the cardiovascular response to isometric exercise is directly influenced by the size of the contracting muscle mass.

Adult↗
PubMed1983

Effects of acute moderate-intensity exercise on carnitine metabolism in men and women.

The purpose of this investigation was to describe the dynamics of carnitine metabolism during an acute episode of exercise. Twenty-eight subjects (14 male; 14 female) exercised for 40 min on a bicycle ergometer at 55% of their maximal aerobic capacities. Blood samples were obtained at rest, 10, 20, 30, and 40 min of exercise, and 15-min postexercise. Muscle biopsies of the vastus lateralis were performed before and after exercise. Results demonstrated that the percent of acylated plasma carnitine increased significantly (P less than 0.05) across all subjects from 17.3% at rest to 22.3% by 40 min of exercise and continued to increase to 22.8% 15-min postexercise. Total muscle carnitine levels fell significantly (P less than 0.001) across all subjects from 4.21 (1.27) (means +/- SD) mumol/g wet weight at rest to 3.29 (1.27) mumol/g wet weight after exercise. Well-trained males and females had almost identical levels of muscle carnitine [4.35(1.86) and 4.34 (0.64) mumol/g wet weight, respectively]. These levels were somewhat higher but not significantly higher than their moderately trained counterparts [3.86(1.34) and 4.28(1.18) males and females, respectively]. Carnitine palmitoyl transferase (E.C. 2.3.1.21) activity also declined significantly (P less than 0.05) across all subjects after exercise. This study is the first to demonstrate a potential loss of acylated carnitine forms from muscle to plasma during acute exercise, possibly reflecting an increase in carnitine turnover. Alterations in carnitine status may represent another metabolic adaptation to chronic exercise training.

Adult↗
PubMed1983

Estimation of energy expenditure by a portable accelerometer.

A small portable accelerometer was developed to estimate the energy expenditure of daily activities. The accelerometer is reported to be an improvement over movement counters currently on the market. The oxygen requirement of 14 different activities was measured in 21 subjects while each wore the accelerometer on the waist. A movement counter (mercury switch), which is available commercially, was also worn on the waist and another was worn on the left wrist. The reproducibility of the accelerometer readings was high (4 subjects, 14 activities; r = 0.94) and was superior to either the waist movement counter (r = 0.63) or the wrist movement counter (r = 0.74). In estimating oxygen requirement (VO2) the standard error of estimate, based on 21 subjects and 14 activities, was 6.6 ml X min-1 X kg-1 for the accelerometer. This was also better (smaller) than for the waist movement counter (9.2 ml X min-1 X kg-1) or for the wrist movement counter (7.9 ml X min-1 X kg-1).

Energy Metabolism↗
PubMed1982

In vivo leucine oxidation at rest and during two intensities of exercise.

After ingestion of a mixed diet containing a tracer dose (10 muCi) of L-[1-14C]leucine (Leu), 32 male Sprague-Dawley rats (70-90 g) remained at rest (R) or completed 1 h exercise at 80 (E80) or 40% VO2max (E40). 14CO2 production was assessed for 6 h (exercise occurred from h 2 to 3). Four rats were killed at 2, 3, 4, and 6 h (R), at 3 and 6 h (E80), and at 6 h (E40). Determinations were 1) tissue specific activity dpm X mumol-1 from a) mixed skeletal muscle (gastrocnemius, soleus, quadriceps, and hamstrings) and b) liver and 2) radioactivity remaining in the gastrointestinal tract (GIT). Leu oxidized (mumol) was estimated (14 CO2 dpm X tissue sp act dpm-1 X mumol-1) independently from skeletal muscle and liver. Results were 1) 14CO2 production increased in both E80 and E40 compared with R (P less than 0.05), 2) E80 14CO2 increase was greater than E40 (P less than 0.05), 3) GIT absorption was reduced in E80 and E40 compared with R (P less than 0.05), and 4) exercise Leu oxidation (weighted average of tissue estimates) was 26% greater than R (P less than 0.05). The origin and site of the increased Leu oxidation cannot be determined from the present data; however, due to the magnitude of increase in skeletal muscle metabolism relative to other tissues during exercise, it is probable that skeletal muscle plays a significant role.

Animals↗
PubMed1982

Comparison of hemodynamic responses to static and dynamic exercise.

Eight healthy male adults (25-34 yr) were studied to compare hemodynamic responses to static exercise (30% MVC in leg extension), static-dynamic exercise (one-arm cranking, 66 and 79% VO2 max-arm), and dynamic exercise (two-leg cycling, 58 and 82% VOmax-legs). Leg extension (LE) strength was measured by a spring scale. Cranking and cycling were performed on a Quinton bicycle ergometer. VO2 was measured using an automated open-circuit system. Heart rate (HR) was monitored from a CM-5 ECG lead, and arterial pressure (Pa) was measured from an indwelling brachial artery catheter. Cardiac output (Q) was measured using a CO2-rebreathing procedure. Total peripheral resistance (TPR) was calculated using the mean arterial pressure (Pa) as the systemic pressure gradient. In 30% LE, a significant (P less than 0.05) Pa increase occurred (pressor response) mediated primarily by an increase in Q. One-arm cranking and two-leg cycling at similar relative VO2 demands resulted in nearly identical increases in Pa due to different contributions of Q and TPR. Q and the arteriovenous O2 difference varied as a function of VO2 regardless of the mode of exercise (static or dynamic). On the other hand, the HR response, which accounted for increased Q in the exercises containing a static component, and Pa varied with mode of exercise. Any generalized scheme of cardiovascular control during exercise must account for the potential influence of dynamic and static components of the exercise.

Adult↗
PubMed1981

Effects of exercise on protein and amino acid metabolism.

At rest, especially during starvation, protein (via hepatic gluconeogenesis and/or direct oxidation) contributes significantly to the body's total metabolic requirement. During exercise, carbohydrate (CHO) and free fatty acids (FFA) are generally regarded as the major energy sources. Although protein has the capability, it has seldom been considered as an important exercise energy source based largely on 24-h urinary nitrogen (N) excretion values. Contrary to classical belief, recent determinations of N in sweat suggest that total N excretion is in fact increased with exercise. This should not be surprising when one considers that prolonged exercise substrate shifts and hormonal changes are in many ways analogous to the situation that occurs during starvation. In addition, in vitro experiments have demonstrated that skeletal muscle, as well as liver, has the capacity to oxidize a number of amino acids. This information, together with the in vivo exercise observations of an increased alanine output from skeletal muscle and an increased 14CO2 evolution following [14C] leucine injection or ingestion, indicates that some amino acids contribute to exercise energy needs. Although a number of mechanisms have been suggested, the current evidence strongly suggests that the branched-chain amino acids (glucose-alanine cycle) are the most important. In conclusion, it appears that the earlier studies which indicated that protein/amino acid utilization did not increase during exercise may have been premature. Although clearly not as important as either CHO or FFA, recent investigations employing both humans and laboratory animals suggest that protein/amino acids, under some conditions, may contribute significantly to total exercise calories.

Amino Acids↗
PubMed1980

Effect of work intensity and duration on recovery O2.

This study was undertaken to determine the effects of exercise intensity and duration on the time course and magnitude of recovery O2. Eighteen men exercised at 50, 65, and 80% of maximal O2 consumption (VO2max) for 5 and 20 min. Each exercise bout was preceded and followed by cycling at 150 kpm.min-1, which established the base-line VO2 used in this study. The magnitude of the rapid component of recovery O2 was proportional to exercise intensity and was not altered by exercise duration. The slow component of recovery O2 was not significantly altered by exercise intensity or duration at 50 and 65% of VO2max. However, after 20 min of exercise at 80% of VO2max, the slow component of recovery 02 was 5 times (p less than 0.01) larger than after the 5-min exercise at 80% of VO2max. End-exercise blood lactate level was also higher after the 20-min bout at 80% of VO2max; however, at most, 30% of the difference between the magnitude of the slow components of recovery O2 after the 5- and 20-min rides at 80% of VO2max could be accounted for by lactate metabolism. The Q10 effect of temperature on metabolism could account for 60-70% of the slow components of recovery O2 at all work rates and durations. It could also account for the remaining 70% of the increase in the slow component after the 20-min exercise at 80% of VO2max.

Adult↗
PubMed1979

Effect of hyperoxia on oxygen consumption in exercising ponies.

Published reports of oxygen consumption (VO2) during exercise in hyperoxia are equivocal. By and large, when measured at the lung using respiratory gas equations, VO2 is elevated in hyperoxia and, when measured at the blood-tissue level using the cardiovascular Fick (CVF) equation, it is unchanged. We sought to provide some insight into this problem by making through the use of both equations simultaneous determinations of VO2 during hyperoxia in exercising ponies. In normoxia, during treadmill exercise (115 m/min, 10% grade) of seven ponies, there was no difference in exercise VO2, whether it was measured by the Haldane transformation (HT) or CVF equations (P greater than 0.05). In hyperoxia, the exercise VO2 was significantly increased from the normoxia condition (P less than 0.05) when measured by the HT equation but not when measured by the CVF equation (P greater than 0.05). By use of the CVF equation as the method of choice for VO2 determinations in hyperoxia, the present data show no change in exercise VO2 in the hyperoxic condition.

Animals↗
PubMed1978

Transient O2 uptake response at the onset of exercise.

One purpose of this study was to determine whether the half time of the oxygen consumption (VO2) response at the onset of exercise varies with work intensity. Fifteen subjects performed 5 min of bicycle ergometer exercise across a range of relative work loads with VO2 determined continuously via computer analysis. The results revealed that the half time of the VO2 response increased as work intensity increased. Our second purpose was to determine whether VO2 response kinetics are dependent on the maximum oxygen uptake (VO2max) of the subject. When VO2 response kinetics were compared at equal absolute work loads for a highly trained (n = 8, mean VO2max = 70.2 ml/kg.min) and an untrained (n = 7, mean VO2max = 49.7 ml/kg.min) group, the highly trained group had a more rapid VO2 response (P less than 0.05). The same tendency was evident at equal relative work loads but the differences were not significant. The more rapid adaptation of the highly trained subjects at absolute work loads may be caused by the enzymatic and circulatory adaptations which result from endurance training. The more rapid adjustment of VO2 at the onset of exercise may explain the slower phosphagen and glycogen depletion found in highly trained subjects following short-term work at equal absolute loads.

Adult↗
PubMed1978

Oxygen consumption during constant-load exercise.

Previous investigators have reported that oxygen consumption (VO2) continues to rise after the initial 2- to 3-min transient period of exercise when work exceeds approximately 60% of VO2 max. The purpose of this investigation was to examine the possible causes of this slow rise in VO2. Eighteen subjects exercised for 20 min at 65% and at 80% of VO2 max on the bicycle ergometer. VO2, ventilation (VE), and respiratory exchange ratio were monitored by a continuous computer-based system. Blood lactate concentration and rectal temperatures were measured at 2- to 3-min intervals during the exercise. VO2 increased significantly from the 5th to 20th min of exercise in 81% of the tests at both levels of work intensity. The magnitude of the rise was not different for the two work loads. No evidence was found to support the lactacid explanation proposed for this rise. Increased temperature could account for 30% of the rise; the estimated cost of increased VE could account for 30 and 81% of the rise at the two work loads. The sum of these factors could account for 60 and 111% of the rise in VO2 at the 65 and 80% of VO2 max work loads.

Adult↗
PubMed1977

Maximal O2 uptake of boys and girls -- ages 14--17.

White high school girls (n = 120) and boys (n = 120) aged 14--17 years, selected from 9th, 10th, 11th and 12 grades of a northern, midwest U.S. high school performed running exercise on a motor driven treadmill for determinations of maximal O2 uptake (VO2 max). The mean VO max for all age groups was 40.8 +/- 4.0 and 54.7 +/- 5.6 ml/kg-min-1 for girls and boys respectively. The difference in VO2 max across age groups varied only from 40.2--41.2 ml/kg-min-1 for girls and 54.0-56.3 ml/kg-min-1 for boys. These differences were not significant (P greater than 0.05). The reported VO2 max data are compared with those reported in other studies for bicycle ergometer and treadmill excercise using similar age groups.

Adolescent↗