Iron-Deficiency Anaemia: Its Effect on Maximum Aerobic Power and Responses to Exercise in African Males Aged 17–40 Years

1973 ◽  
Vol 44 (6) ◽  
pp. 555-562 ◽  
Author(s):  
C. T. M. Davies ◽  
A. C. Chukweumeka ◽  
J. P. M. Van Haaren
Keyword(s):  
Cardiac Output ◽  
Plasma Volume ◽  
Aerobic Power ◽  
Minute Ventilation ◽  
Haemoglobin Concentration ◽  
Work Load ◽  
Severe Anaemia ◽  
Bicycle Ergometer ◽  
Oxygen Intake ◽  
Maximum Aerobic Power

1. The physiological responses to exercise of two groups of industrial workers with moderate and severe anaemia were measured and compared with a group of matched controls, working and living under similar conditions. Exercise was performed on a stationary bicycle ergometer at five consecutive work loads. During the final minute of each exercise periods, oxygen intake, minute ventilation volume, and cardiac and respiratory frequencies were measured. On a separate occasion, blood haemoglobin concentration was measured at rest and cardiac output and blood and plasma volumes were estimated while subjects exercised at a fixed percentage of the maximum aerobic power for 6 min. 2. Oxygen intake for a given work load and ventilation rate was similar in all subjects studied but exercise cardiac output was elevated in the anaemic group. The increased cardiac output was due to an increased heart rate, the stroke volume being similar in the anaemic and control subjects. There was a marked decrement (∼34%) in maximum aerobic power and some evidence of a raised plasma volume in the severely anaemic group. 3. These results suggest that anaemia impairs performance during moderate and near maximum exercise. There is an associated rise of cardiac output and plasma volume.

Effects of glycogen depletion and work load on postexercise O2 consumption and blood lactate

1979 ◽  
Vol 47 (3) ◽  
pp. 514-521 ◽  
Author(s):  
S. S. Segal ◽  
G. A. Brooks
Keyword(s):  
Blood Lactate ◽  
Slow Component ◽  
Minute Ventilation ◽  
Co2 Flux ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Co2 Production ◽  
O2 Consumption ◽  
Glycogen Depletion ◽  
Heavy Exercise

To study a possible relationship between blood lactate and O2 consumption (VO2) after exercise, 11 male subjects exercised on a bicycle ergometer at moderate and heavy work loads in both normal glycogen and glycogen-depleted states. At rest, glycogen depletion resulted in significantly lowered blood glucose and lactate concentrations, CO2 production (VCO2), respiratory exchange ratio (R), and minute ventilation (VE). With the exception of glucose, these variables changed more in response to heavy exercise (HE: 2 min at a mean of 1,750 kg.m/min) than to moderate exercise (ME: 2 min at a mean of 1,000 kg.m/min). At either work load, VCO2, R, and lactate showed consistently greater responses in the normal glycogen state. The slope of the initial component of the postexercise VO2 curve was unaffected by either work load or lactate. Although the slope of the slow component of the postexercise VO2 curve became significantly more negative after HE, it was unaffected by the level of lactate. These results are inconsistent with the hypothesis of a “lactacid O2 debt.” Exercise intensity was the predominant factor influencing the magnitude and kinetics of postexercise VO2. Glycogen depletion resulted in lower VCO2, R, and blood lactate, but higher VE during heavy exercise. The results suggest that factors, in addition to CO2 flux to the lungs, influence VE during exercise.

Respiratory Responses to Simultaneous Static and Rhythmic Exercises in Humans

1975 ◽  
Vol 49 (5) ◽  
pp. 427-432 ◽  
Author(s):  
R. L. Wiley ◽  
A. R. Lind
Keyword(s):  
Oxygen Consumption ◽  
Minute Ventilation ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Hand Grip ◽  
Static Effort ◽  
The Mean ◽  
Rhythmic Exercise ◽  
Male Subjects ◽  
Respiratory Responses

1. Six male subjects performed simultaneous static (hand-grip) and rhythmic (bicycle ergometer) exercises while their respiratory responses were measured. 2. Oxygen consumption increased with the intensity of rhythmic work load, with a modest additional oxygen consumption accompanying the addition of static effort during the rhythmic exercise. 3. Minute ventilation (V̇E) increased directly with rhythmic exercise, but increased disproportionately to the metabolic need when static effort was added. The mean increment of V̇E elicited by the static exercise influence was nearly constant at 20 1/min, regardless of the rhythmic load present. 4. Possible reflex mechanisms which result in disruption of the normally well-matched ventilation and metabolic oxygen demands whenever static effort is present are discussed.

Perception of Exertion in the Elderly, Effects of Aging, Mode of Exercise and Physical Training

1977 ◽  
Vol 44 (3) ◽  
pp. 999-1010 ◽  
Author(s):  
K. H. Sidney ◽  
ROY. J. Shephard
Keyword(s):  
Perceived Exertion ◽  
Work Load ◽  
The Elderly ◽  
Exercise Programme ◽  
Bicycle Ergometer ◽  
Oxygen Intake ◽  
Unexpected Result ◽  
Maximum Oxygen Intake ◽  
Heart Rates ◽  
Ergometer Exercise

Ratings of perceived exertion by the Borg psychophysical scale have been made on 26 men and 30 women aged 60 to 70 yr. All were volunteers for a pre-retirement exercise programme. During progressive bicycle ergometer exercise lines relating the ratings of exertion to heart rate were closely similar in men and women, scores at all heart rates being 2 or 3 units higher than in young adults. A brief progressive exercise protocol on the treadmill yielded somewhat lower ratings than bicycle ergometer work, the discrepancy being marked in women. At any given oxygen intake, ratings were higher for females than males and higher for old than young subjects. However, when oxygen intake was expressed as a percentage of the directly measured maximum oxygen intake, scores became independent of sex and age. A 34-wk. period of conditioning substantially reduced heart rates but had little effect on the perception of effort at a given work load. This unexpected result may reflect a closer approximation of core and skin temperatures with reduction of sub-cutaneous fat.

Changes in Physiological Performance of the Lower Limb after Fracture and Subsequent Rehabilitation

1975 ◽  
Vol 48 (2) ◽  
pp. 107-114
Author(s):  
C. T. M. Davies ◽  
A. J. Sargeant
Keyword(s):  
Minute Ventilation ◽  
Bicycle Ergometer ◽  
Rehabilitation Programme ◽  
Oxygen Intake ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Maximum Oxygen Intake ◽  
Before And After ◽  
Leg Exercise ◽  
Subsequent Rehabilitation

1. Eight patients who had suffered a fracture of one leg were studied before and after a 7 weeks period of rehabilitation during work with one leg and both legs on a bicycle ergometer. 2. In submaximal exercise minute ventilation for a given carbon dioxide output and tidal volume at a given minute ventilation remained unchanged throughout the period of therapy for both one- and two-leg exercise: oxygen intake for a given work output and cardiac frequency for a given oxygen intake decreased in both the injured and uninjured limb during one-leg work, although in two-leg exercise there was no significant change. 3. Oxygen intake at zero load was subtracted from the maximum oxygen intake measured during loaded exercise to give net values for each limb exercised separately or both legs exercised together. The net maximum oxygen intake thus calculated increased 8.9% (+ 0.17 l/min) in the uninjured leg and 17.4% (+0.29 l/min) in the injured leg during one-leg exercise. In two-leg exercise the increase was 17.2% (+ 0.43 l/min), which approximately equals the increase in the two legs measured separately. 4. In both legs there was an increase in leg muscle (plus bone) volume although this was significant in the injured leg only. 5. The maximum oxygen intake attained in two-leg exercise for a given leg volume in the patients at discharge was not significantly different from that found previously in a cross-sectional survey of young healthy (naval) servicemen. Thus the rehabilitation programme investigated appears to be effective, although the spontaneous recovery without a rehabilitation programme is unknown.

Dynamics of cardiac, respiratory, and metabolic function in men in response to step work load

1982 ◽  
Vol 52 (5) ◽  
pp. 1198-1208 ◽  
Author(s):  
Y. Miyamoto ◽  
T. Hiura ◽  
T. Tamura ◽  
T. Nakamura ◽  
J. Higuchi ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Time Constant ◽  
Minute Ventilation ◽  
Initial Period ◽  
Work Load ◽  
Work Intensity ◽  
Control Value ◽  
End Tidal

Stroke volume, heart rate, cardiac output, tidal volume, respiratory frequency, minute ventilation, end-tidal tensions of O2 and CO2, O2 uptake, CO2 output, and respiratory exchange ratio were measured simultaneously in healthy male volunteers before, during, and after upright bicycle exercise from 0 to 360 and 720 kpm/min. The circulatory variables were determined continuously once per 20 cardiac cycles and the respiratory variables breath by breath using separate computer-based systems in which an impedance pneumograph and an impedance cardiograph were incorporated. Stroke volume, heart rate, and cardiac output started to increase without measurable delay at the onset of exercise. Stroke volume increased by 20% from resting control value in response to the mildest exercise and essentially leveled off with a further increase in work load. Time constant for cardiac output increased with the increasing work load. Time constant for minute ventilation was much longer than that for cardiac output and independent of work intensity. A good synchronization between the ventilation and cardiac output responses at an initial period of transitions from rest to exercise and from exercise to rest seems to support the concept of cardiodynamic hyperpnea.

scholarly journals Heart mass and the maximum cardiac output of birds and mammals: implications for estimating the maximum aerobic power input of flying animals

1997 ◽  
Vol 352 (1352) ◽  
pp. 447-456 ◽  
Author(s):  
Charles M. Bishop
Keyword(s):  
Cardiac Output ◽  
Muscle Mass ◽  
Heart Muscle ◽  
Flight Muscle ◽  
Aerobic Power ◽  
Power Input ◽  
Large Species ◽  
Flight Performance ◽  
Confounding Variable ◽  
Maximum Aerobic Power

Empirical studies of cardiovascular variables suggest that relative heart muscle mass (relative M h ) is a good indicator of the degree of adaptive specialization for prolonged locomotor activities, for both birds and mammals. Reasonable predictions for the maximum oxygen consumption of birds during flight can be obtained by assuming that avian heart muscle has the same maximum physiological and biomechanical performance as that of terrestrial mammals. Thus, data on M h can be used to provide quantitative estimates for the maximum aerobic power input (aerobic P i, max ) available to animals during intense levels of locomotor activity. The maximum cardiac output of birds and mammals is calculated to scale with respect to M h (g) as 213 M h 0.88±0.04 (ml min −1 ), while aerobic P i,max is estimated to scale approximately as 11 M h 0.88±0.09 (W). In general, estimated inter–species aerobic P i,max , based on M h for all bird species (excluding hummingbirds), is calculated to scale with respect to body mass ( M b in kg) as 81 M b 0.82±0.11 (W). Comparison of family means for M h indicate that there is considerable diversity in aerobic capacity among birds and mammals, for example, among the medium to large species of birds the Tinamidae have the smallest relative M h (0.25 %) while the Otidae have unusually large relative M h (1.6 %). Hummingbirds have extremely large relative M h (2.28 %), but exhibit significant sexual dimorphism in their scaling of M h and flight muscle mass, so that when considering hummingbird flight performance it may be useful to control for sexual differences in morphology. The estimated scaling of aerobic P i,max (based on M h and M b in g) for male and female hummingbirds is 0.51 M b 0.83 ±0.07 and 0.44 M b 0.85± 0.11 (W), respectively. Locomotory muscles are dynamic structures and it might be anticipated that where additional energetic ‘costs’ occur seasonally (e.g. due to migratory fattening or the development of large secondary sexual characteristics) then the relevant cardiac and locomotor musculature might also be regulated seasonally. This is an important consideration, both due to the intrinsic interest of studying muscular adaptation to changes in energy demand, but also as a confounding variable in the practical use of heart rate to estimate the energetics of animals. Haemoglobin concentration (or haematocrit) may also be a confounding variable. Thus, it is concluded that data on the cardiovascular and flight muscle morphology of animals provides essential information regarding the behavioural, ecological and physiological significance of the flight performance of animals.

Circulatory response to submaximal and maximal exercise after thermal dehydration

1964 ◽  
Vol 19 (6) ◽  
pp. 1125-1132 ◽  
Author(s):  
Bengt Saltin
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Plasma Volume ◽  
Maximal Exercise ◽  
Work Load ◽  
Sitting Position ◽  
Dye Dilution ◽  
Significant Difference

Data on cardiac output and stroke volume are given for four subjects at various levels of muscular work up to the individual's maximum. No significant difference was found between the dye-dilution and the acetylene methods. Three subjects were studied under normal conditions and after dehydration (exposure to heat with a reduction in body weight of up to 5.2%); circulatory data were measured at rest and during exercise at two submaximal and one maximal work load. The decrease in body weight was accompanied by a reduction in plasma volume of up to 25%. After dehydration, the major change in the hemodynamic response to work in a sitting position at the submaximal loads was a decrease in stroke volume and an associated increase in heart rate, so that the cardiac output remained almost unaltered. Both these changes were significantly correlated to the reduction in body weight and plasma volume. When after dehydration the submaximal work load was performed in a supine position, no increase in heart rate was noticed compared with that before dehydration. Dehydration produced no significant change in oxygen uptake, cardiac output, or stroke volume during maximal exercise in a sitting position. However, the maximal work time was much shorter and there was a marked decrease in maximal blood lactate. comparison dye-dilution-acetylene methods; plasma volume; lactic acid Submitted on August 12, 1963

Oxygen intake and cardiac output during maximal treadmill and bicycle exercise

1972 ◽  
Vol 32 (2) ◽  
pp. 185-188 ◽  
Author(s):  
Miharu Miyamara ◽  
Yoshiyuki Honda
Keyword(s):  
Cardiac Output ◽  
Treadmill Exercise ◽  
Bicycle Ergometer ◽  
Oxygen Intake ◽  
Bicycle Exercise ◽  
Maximum Oxygen Intake ◽  
Ergometer Exercise ◽  
Lower Maximum ◽  
Bicycle Ergometer Exercise ◽  
Incremental Loading

Oxygen intake and cardiac output were measured in 17 male students, aged 18–23 years, during maximal treadmill and bicycle ergometer exercise with stepwise incremental loading and constant loading. The average values of oxygen intake and cardiac output during treadmill exercise were higher than during bicycle ergometer exercise, either with incremental loading or constant loading. These differences were statistically significant (P < 0.001–0.01). No statistically significant differences are found in stroke volume, whereas significant differences were seen in maximum heart rate between all four different modes of exercise. Arteriovenous oxygen differences were higher during treadmill exercise than during bicycle ergometer exercise. It is suggested that lower maximum oxygen intake during bicycle ergometer exercise is related to the lower maximum cardiac output and lower arteriovenous oxygen differences as compared with treadmill exercise. maximum oxygen intake; maximum cardiac output; maximum heart rate; stroke volume during maximal exercise; arteriovenous oxygen difference during maximal exercise; comparison of treadmill and bicycle exercise

Cardio-Respiratory Response to Exercise in Normal Children

1971 ◽  
Vol 40 (5) ◽  
pp. 419-431 ◽  
Author(s):  
S. Godfrey ◽  
C. T. M. Davies ◽  
E. Wozniak ◽  
Carolyn A. Barnes
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Steady State ◽  
Minute Ventilation ◽  
Work Load ◽  
Normal Children ◽  
Progressive Exercise ◽  
Maximum Work ◽  
Response To Exercise ◽  
Submaximal Heart Rate

1. The results of studies during simple progressive exercise to exhaustion and steady-state submaximal exercise in 117 boys and girls aged 6–16 years are presented. 2. In the simple progressive exercise test, the highest work load achieved and the submaximal heart rate were related to size and sex. The maximum heart rate and submaximal ventilation were largely independent of size and sex. 3. Steady-state exercise was performed at one-third and two-thirds of the maximum work load achieved in the simple progressive test. The Indirect (CO2) Fick method was used to measure cardiac output. 4. At any given level of steady-state work, tidal volume, dead space, heart rate and stroke volume were closely related to size, with girls having higher heart rates and smaller stroke volumes than boys. Minute ventilation and cardiac output were virtually independent of size and sex. The cardiac output in children was the same as that in the adult for any given oxygen consumption. Blood lactate was related to size at any given work load, but was independent of size at any given fraction of the maximum working capacity.

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