Showing papers on "Aerobic capacity published in 1988"
TL;DR: Variations in heart rate during exercise correlate with changes of exercise intensity and may be measured directly by radiotelemetry and continuous ECG recording, which has been used to measure the physical work load in alpine skiing.
Abstract: Variations in heart rate during exercise correlate with changes of exercise intensity and may be measured directly by radiotelemetry and continuous ECG recording. The heart rate can also be recorded in the memory of a microcomputer, which can be carried on the wrist as easily as a watch. The device has a transmitter and a receiver. By recording the heart rate during a training session or a segment of training, and calculating the average of the heart rate and comparing this average to both the maximum heart rate of the individual and his heart rate at rest, the relative heart rate to the intensity of the work load (% maximum heart rate) can be calculated. These results are useful in planning optimal training intensities for both the healthy and rehabilitating athlete. The use of target heart rate as a tool for exercise prescription is common. It represents the percentage difference between resting and maximum heart rate added to the resting heart rate. For calculating target heart rate there are also 2 other methods. The first represents the percentage of the maximum heart rate (%HRmax) calculated from zero to peak heart rate. The second represents the heart rate at a specified percentage of maximum MET (V2max). An appropriate individual heart rate for each level of an endurance performance is best determined in the laboratory. This is carried out by increasing the speed of the runner in stages on a treadmill and by measuring the oxygen uptake, the lactic acid concentration in the blood and corresponding variations in the heart rate. From these results the running speed and heart rate corresponding to aerobic, partly anaerobic or strongly anaerobic running can be determined. The %HRmax values obtained by continuous ECG recording and telemetry have been used to measure the physical work load in alpine skiing. Alpine skiing has been recorded as exercise which improves general physical fitness and aerobic capacity. However, it has been found to increase more the anaerobic capacity than the aerobic capacity. This should be taken into consideration when planning the training of general physical fitness of alpine skiers.
537 citations
TL;DR: Results indicated that there were significant differences on posttest scores between the control and exercise groups on state anxiety, trait anxiety and depression, but not on self-concept or aerobic capacity.
Abstract: This study examined the usefulness of physical exercise as a treatment intervention to decrease depression and anxiety in adult inpatient alcoholics while increasing aerobic capacity and self-concept. The State-Trait Anxiety Inventory, the Tennessee Self-Concept Scale, the Self-Rating Depression Scale and the Astrand-Rhyming bicycle-ergometer were administered to a treatment and a control group on admission to and again at discharge from a 28-day inpatient treatment program. Control group data were gathered prior to initiating the exercise program. The exercise program consisted of walking or jogging 3 days a week and was designed to meet the American College of Sports Medicine's minimum requirements for a graded exercise program. Results indicated that there were significant differences on posttest scores between the control and exercise groups on state anxiety, trait anxiety and depression, but not on self-concept or aerobic capacity. The usefulness of physical exercise as a treatment intervention as well as the implication for research are discussed.
61 citations
TL;DR: The locomotory muscles of the tufted duck were analysed for mass, aerobic and anaerobic enzyme activities, fibre-type proportions, capillarity, mitochondrial and myoglobin content and suggest that exercise performance in birds cannot be predicted purely on the basis of muscle mass.
Abstract: The locomotory muscles of the tufted duck, Aythya fuligula (L.), were analysed for mass, aerobic and anaerobic enzyme activities, fibre-type proportions, capillarity, mitochondrial and myoglobin content. The estimated aerobic capacity of the muscles correlated well with the muscles' maximal oxygen uptake both when measured during swimming and when predicted for steady-state flight. The results suggest that exercise performance in birds cannot be predicted purely on the basis of muscle mass (see Butler & Woakes, 1985); the specific enzyme complement of each muscle must also be taken into account. The delivery of oxygen to mitochondria is facilitated by the dense capillarity and high myoglobin content of the muscles.
59 citations
TL;DR: To evaluate the necessity of an objective cardiopulmonary exercise test in the selection procedure of patients for heart failure studies, 50 patients with congestive heart failure New York Heart Association (NYHA) class II and III and a left ventricular ejection fraction less than 40% were subjected to a cardiopula exercise test.
58 citations
TL;DR: It is suggested that the adaptable structures upstream to the muscle mitochondria are built and maintained at a cost-benefit maximum ("structural efficiency") in all species, unlike the concept of optimal structural design or symmorphosis.
Abstract: In this paper we have explored the linked series of structures that collectively comprise the respiratory system. In examining each of these structural resistors, some seem to be primarily fixed, for example, the trachea, while others must be primarily variable or adaptable, for example, the cardiovascular system. Those structures that are truly variable will not be maintained with structural capacity in excess of their functional demand. As a consequence, these structures are the ones that may most often appear to be limiting O2 uptake. However, we question under which in vivo circumstances the most plastic steps in the cascade of resistances will impart the single-step limitation to O2 uptake. When reviewed in this context, available experimental evidence suggests that among the most athletic animals (those with the greatest weight-specific VO2), the respiratory resistors are likely tuned rather than dominated by a single-step limitation. Skeletal muscle must set the demand for O2 in exercising animals; hence, the relationship between total skeletal muscle mitochondria and maximum O2 consumption is quantitatively consistent, spanning broad differences in body size and aerobic capacity. Those respiratory structures that are primarily nonadaptable must be built with enough "excess structure" to accommodate potential adaptation in an animal's aerobic capacity during its lifetime. Consequently, the least aerobic animals will always appear to experience a limitation to VO2max in one of the most plastic or adaptable structures. We suggest that the adaptable structures upstream to the muscle mitochondria are built and maintained at a cost-benefit maximum ("structural efficiency") in all species. This differs from the concept of optimal structural design or symmorphosis.
58 citations
Journal Article•
TL;DR: There is a rather well-maintained adaptability for increasing physical activity and for training in the elderly with respect to strength as well as endurance and, as an extreme example in very well trained elderly endurance athletes, high activity of citrate synthase is found and, in connection with that, low plasma insulin values at baseline and after glucose intake.
Abstract: With aging, several functions related to the locomotor system will deteriorate. Still, there is a rather well-maintained adaptability for increasing physical activity and for training in the elderly with respect to strength as well as endurance. Part of the observed reduction in muscle function with age could therefore be caused by inactivity. Evidently, however, there is a reduction in muscle mass with age due to loss of motor units. Muscle strength and aerobic power will fall fairly proportionally to the reduction in muscle mass. The muscle changes are, at least up to around the age of 70, more quantitative than qualitative. There is a reduction in the size of the fast-twitch (type II) fibers in the quadriceps, but not in other muscles such as the biceps brachii, presumably due to differences in activity pattern and motor unit recruitment. Aging per se may not reduce oxidative enzymatic capacity in the skeletal muscle. There is maintained potential for increase with endurance training. Thus, as an extreme example in very well trained elderly endurance athletes, high activity of citrate synthase is found and, in connection with that, also low plasma insulin values at baseline as well as after glucose intake. Limitations to aerobic capacity besides the reduced muscle mass are mainly located in the central circulatory and respiratory systems. Comparing the oxygen cost of activities in daily living, such as walking, and the aerobic power of the elderly, suggestions will be given on the choice of training activities.
52 citations
TL;DR: Compliance to regular exercise in hemodialysis patients remains a problem, however, exercise training during the dialysis treatment may prove beneficial in terms of compliance and supervision.
Abstract: • Available studies indicate that exercise tolerance in renal patients is low. Although significant improvements in maximal oxygen consumption have been reported following exercise training in these patients, there may be physiologic limitations to the attainable levels of aerobic capacity due to the multisystemic nature of the disease. Long-term exercise training may result in other medical benefits. Compliance to regular exercise in hemodialysis patients remains a problem, however, exercise training during the dialysis treatment may prove beneficial in terms of compliance and supervision. © 1986 by the National Kidney Foundation, Inc. INDEX WORDS: Exercise training; exercise capacity; ESRD.
45 citations
Journal Article•
TL;DR: Pregnancy did not reduce maximal oxygen consumption between the second and third trimesters of pregnancy, and whether maintaining a regular exercise program during the second half of pregnancy affects fitness was examined.
42 citations
TL;DR: Results of this study indicate that nonathletic adolescents with insulin-dependent diabetes mellitus can engage in self-motivated exercise training at home and if properly designed, such programs can improve aerobic fitness and may contribute to improvement in diabetes control.
Abstract: In this project we investigated the impact of a 12-week at-home aerobic fitness program on aerobic capacity and metabolic control of ten adolescents (four girls and six boys 12 to 14 years of age) with insulin-dependent diabetes mellitus. The adolescents had no prior experience with exercise training. The 45-minute program, designed by a physical therapist, consisted of a stretching, calisthenics, and "cool-down" routine set to popular music. It was taught to the youngsters in group sessions. Each adolescent was given audio- and videocassettes of the routine for home use that emphasized self-motivation in maintaining training. The youngsters were asked to exercise three times per week and were also taught how to adjust their insulin and diet for exercise. Aerobic fitness was determined by maximal oxygen uptake following a vigorous, continuous progressive cycling test; metabolic control was measured by glycosylated hemoglobin values. All of the adolescents reported greater than 85% completion of the program. The youngsters displayed a correspondingly significant increase in aerobic fitness as measured by maximal oxygen uptake: 40.39 +/- 8.87 v 44.86 +/- 12.89 mL/kg/min. Glycosylated hemoglobin levels (mean +/- SD) for the entire group were significantly reduced after the program (11.41 +/- 4.47% v 10.01 +/- 3.21%). Results of this study indicate that nonathletic adolescents with insulin-dependent diabetes mellitus can engage in self-motivated exercise training at home. If properly designed, such programs can improve aerobic fitness and may contribute to improvement in diabetes control.
41 citations
TL;DR: The preferred fuel for exercise at altitude seems to be fat, while carbohydrate metabolism is dramatically changed and much is not known of high altitude anorexia and muscle mass loss.
Abstract: The effect of altitude on human performance is complex. Numerous variables are known to change from sea-level measures. Maximum aerobic power is depressed as ascent occurs and this impairs the ability to work maximally. While changes in haematological variables would theoretically counterbalance the loss in aerobic power, they have not been shown to do so. The environmental stress of cold may have positive effects on aerobic capacity at altitude, but this has been little investigated in humans. Pulmonary ventilation increases with altitude and the measure of hypoxic ventilatory response holds some promise of predicting humans who may benefit from altitude conditioning. Cardiac function is well maintained while lung function is not. The preferred fuel for exercise at altitude seems to be fat, while carbohydrate metabolism is dramatically changed. Much is not known of high altitude anorexia and muscle mass loss. Conditioning at altitude is known to benefit performance at altitude. The evidence for a sea-level benefit from altitude training as yet remains elusive. While selected individuals may benefit, the reasons why have not been determined.
31 citations
TL;DR: A major objective of medical therapy in patients with heart failure is to improve cardiac output and oxygen delivery to working skeletal muscle and thereby enhance effort tolerance, which can be gauged by cardiopulmonary exercise testing from the response in AT and VO2max.
Abstract: Isotonic exercise testing imposes a physiological stress on the cardiopulmonary unit. Accordingly, monitoring of oxygen, carbon dioxide and air flow during an exercise test (i.e. a cardiopulmonary exercise test) can be used to assess heart function in patients with chronic heart failure. Specifically, an incremental treadmill cardiopulmonary exercise test represents a non-invasive means to determine aerobic capacity, or maximal oxygen uptake (VO2max ml min-1 kg-1), and anaerobic threshold (AT, ml min-1 kg-1). These objective measures of cardiopulmonary function are then used to grade the severity of failure and the functional capacity of the patient. In addition, they may be used to predict the cardiac reserve, or maximal cardiac index (CImax, l min-1 m-2) during exercise. That is, the severity is considered to be mild (class A) when AT greater than 14 or VO2max greater than 20, mild to moderate (class B) when AT falls between 11 and 14 or VO2max between 16 and 20, moderate to severe (class C) when AT ranges between 8 and 11 or VO2max between 10 and 16, and severe (class D) when AT less than 8 or VO2max less than 10. The predicted CImax for classes A, B, C and D are greater than 8, 6-8, 4-6 and less than 4, respectively. Finally, a major objective of medical therapy in patients with heart failure is to improve cardiac output and oxygen delivery to working skeletal muscle and thereby enhance effort tolerance. This therapeutic endpoint can be gauged by cardiopulmonary exercise testing from the response in AT and VO2max.
TL;DR: Participation in the walking program slightly improved aerobic capacity without affecting riboflavin or thiamin status or birth outcome in pregnant women taking vitamin-mineral supplements.
TL;DR: It is reported here that no significant differences in glucose uptake rate or glucose oxidation rate were observed between regenerating myoblasts and myotubes, whereas the aerobic oxidation of palmitic acid increased 7.3-fold between these differentiation states.
Abstract: Regeneration of damaged, mature muscle occurs by differentiation of satellite cells. In culture, satellite cell myoblasts proliferate, align, and fuse to form cross-striated, contracting myotubes. The biochemical changes and the factors that regulate differentiation in satellite cells have not been investigated previously. We report here that no significant differences in glucose uptake rate or glucose oxidation rate were observed between regenerating myoblasts and myotubes, whereas the aerobic oxidation of palmitic acid increased 7.3-fold between these differentiation states. Specific activities of enzymes of critical importance in aerobic metabolism or in production of ATP were increased 2- to 3.5-fold during fusion. Addition of 20 microM hemin to regenerating muscle cultures potentiated the aerobic capacity as evidenced by a 23.6% increase in palmitate oxidation rate. Hemin also increased the specific activities of all nonheme enzymes investigated with the exception of phosphofructokinase. This augmentation of aerobic metabolism together with the time frame of active muscle differentiation suggests a complex role for hemin in myogenesis.
TL;DR: Exercise testing is used to determine the presence or absence of ischemic ST segment depression, stratify patients for morbidity and mortality prognosis, establish maximal heart rates for purposes of exercise prescription, and determine maximal work tolerance or aerobic capacity (AC).
Abstract: INTRODUCTION Exercise testing is used to determine the presence or absence of ischemic ST segment depression, stratify patients for morbidity and mortality prognosis, establish maximal heart rates for purposes of exercise prescription, and determine maximal work tolerance or aerobic capacity (AC)J Measurement of AC provides an indirect means of assessing the capacity of the heart as a pump, since maximal oxygen uptake is the product of maximal cardiac output times the arteriovenous oxygen difference. The maximal arteriovenous oxygen difference varies only slightly in untrained and trained subjects; thus, cardiac output is the primary determinant of oxygen uptake.
Journal Article•
01 Dec 1988
TL;DR: It is demonstrated that altitude hypoxia and carbon monoxidehypoxia act independently on the parameters of the maximal aerobic capacity test and a decrease in thecarbon monoxide concentration to carboxyhemoglobin as altitude increased is demonstrated.
Abstract: In order to assess the combined effects of altitude and acute carbon monoxide exposure, 11 male and 12 female subjects, nonsmokers in good health, were given incremental (two minutes at each workload) maximal aerobic capacity tests at four levels of ambient carbon monoxide (0, 50, 100, and 150 parts per million) at four altitudes (55, 1,524, 2,134, and 3,048 m). Five male and four female subjects completed all 16 experiments. The remaining subjects completed either eight or 12 experiments; at least eight male and eight female subjects were tested at each combination of carbon monoxide and altitude. Test conditions were double-blind. Subjects initially were screened with a medical history questionnaire, a 12-lead electrocardiogram, pulmonary function tests, anthropometric and body fat measurements, blood volume determinations, and a maximal aerobic capacity test. Each subject, after attaining the required altitude and ambient carbon monoxide level, performed the maximal aerobic capacity test (maximum VO2) meeting required conditions to assure that a maximal level was attained. Blood samples were drawn prior to the aerobic capacity test; at workloads of 50 watts, 100 watts, 150 watts, and maximum; at the fifth minute of recovery; and prior to repressurization to sea level. Blood was analyzed for hemoglobin, hematocrit, plasma proteins, lactates, and carboxyhemoglobin. Carbon-monoxide-carboxyhemoglobin uptake rates were derived from the submaximal workloads. Maximum VO2 was similar at 55 m and 1,524 m, and decreased from the 55-m value by 4 percent at 2,134 m and by 8 percent at 3,048 m. Despite increases in carboxyhemoglobin, no additional significant decreases in maximal aerobic capacity were observed. With increasing carbon monoxide, a decrease in maximum VO2 independent of altitude was observed. Carboxyhemoglobin concentrations at maximum VO2 were highest at 55 m and lowest at 3,048 m. Carboxyhemoglobin concentrations were lower in female subjects than in male subjects. Immediately prior to and at maximal workloads, carbon monoxide shifted into extravascular spaces and returned to the vascular space within five minutes after exercise stopped. We demonstrated that altitude hypoxia and carbon monoxide hypoxia act independently on the parameters of the maximal aerobic capacity test. We also demonstrated a decrease in the carbon monoxide concentration to carboxyhemoglobin as altitude increased, which can be attributed to the decrease in driving pressure of carbon monoxide at altitude. Language: en
TL;DR: Long-term exercise training that increases aerobic power thus maintains normoglycemia with lower insulin values than in otherwise physically fit postmenopausal women.
01 Jan 1988
TL;DR: It is concluded that in man the dynamics of the ventilatory response to exercise depend on the actual level of VO2max in the individual.
Abstract: Some respiratory reactions show a relation to the physical fitness of an individual indicating that respiratory mechanisms can play a role in functional adaptation to exercise in man. Stegemann (1981) has reported that trained and untrained persons have the same ventilation at rest but that this is achieved with different ratios of frequency and tidal volume when the respiratory center is stimulated at rest by CO2. As was shown by Yearg et al. (1985) the exercise equivalent for oxygen (VE/VO2) decreases and maximal achievable ventilation (VEmax) increases in the course of endurance training. It is also reported that at the onset of exercise oxygen uptake and ventilation increase more rapidly toward the steady state in trained than in untrained men (Hagberg et al., 1980). The latter finding has an important bearing on the estimation of the oxygen deficit developing in man at the beginning of heavy exercise. It is not clear, however, whether the faster response of ventilation is a specific result of the training applied, or whether it is a physiological reaction connected with the level of maximal aerobic capacity (VO2max) regardless of training. The purpose of this study was, therefore, to test the dynamics of respiratory response to exercise in relation to the individual level of VO2max in a group of untrained men.