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Maximum Oxygen Uptake (maximum + oxygen_uptake)
Selected AbstractsModelling the Influence of Age, Body Size and Sex on Maximum Oxygen Uptake in Older HumansEXPERIMENTAL PHYSIOLOGY, Issue 2 2000Patrick J. Johnson The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (V,O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on V,O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: V,O2,max= BMb (or FFMb) exp(a + (c × age) + (d × sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8% of the variance in V,O2,max. The parameters (± s.e.e., standard error of the estimate) for lnBM (0.563 ± 0.070), age (-0.0154 ± 0.0012), sex (0.242 ± 0.024) and the intercept (-1.09 ± 0.32) were all significant (P < 0.001). The FFM model explained 69.3% of the variance in V,O2,max, and the parameters (± s.e.e) lnFFM (0.772 ± 0.090), age (-0.0159 ± 0.0012) and the intercept (-1.57 ± 0.36) were significant (P < 0.001), while sex (0.077 +/, 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15% per decade (0.984 exp(age)) in V,O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in V,O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of V,O2,max across age is similar in older men and women. [source] Ventilation threshold as a measure of impaired physical performance in adults with growth hormone excessCLINICAL ENDOCRINOLOGY, Issue 3 2002Scott G. Thomas Summary objective Fatigue is a prominent symptom among patients with GH excess and acromegaly. Identifying the physiological basis of such complaints and obtaining objective measures to quantify their severity remains an ongoing challenge. We investigated whether submaximal measures of aerobic performance can be used to assess GH excess-associated fatigue objectively. design and patients To investigate this possibility we examined the relation between physical function and physical capacity in 12 patients with active acromegaly and persistent fatigue before and after 3 and 6 months of treatment with the long-acting somatostatin analogue octreotide (LAR®). measurements Heart rate (HR) and rating of perceived exertion (RPE using Borg's 10-point scale) were measured during a 160-metre self-paced walk test (SPW). Maximum oxygen uptake (VO2max) and ventilation threshold (VeT: a measure of work rate when breathlessness develops) were measured during a progressive treadmill test to fatigue or symptom-limited maximum. The Profile Of Mood States questionnaire (POMS) was used to quantify subjective feelings of fatigue and vigour. Morning fasting levels of GH and IGF-I were measured using immunoassay of serum samples. results SPW speed at a fast pace of 1·69 ± 0·18 m/s was achieved with higher than normal HR (112 ± 15/min; normal = 102) and RPE (2·4 ± 1·2). Similar to GH-deficient adults, VO2max (22·6 ± 6·4 ml.kg,1.min,1; normal ~30 ml.kg,1.min,1) and VeT (13·1 ± 2·9 ml.kg,1.min,1; predicted normal ~16 ml.kg,1(min,1) were low. However, VeT occurred at a normal fraction of VO2max (VeT/VO2max = 0·58). VeT was significantly increased and plasma IGF-I levels reduced following 3 and 6 months of octreotide LAR® treatment. Reduction in circulating IGF-I levels was correlated with improvement in reported vigour (r = 0·85) and VeT (r = 0·65) (P < 0·05). conclusions Our findings demonstrate impairment in physical function and physical capacity consistent with the perception of increased fatigue among acromegalic patients. These objective measures of compromised physical function are similar to the changes that we have reported previously in adults with GH deficiency. Taken together, these data suggest that a narrow window for GH/IGF-I levels is required to maintain optimal physical function. [source] Modelling the Influence of Age, Body Size and Sex on Maximum Oxygen Uptake in Older HumansEXPERIMENTAL PHYSIOLOGY, Issue 2 2000Patrick J. Johnson The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (V,O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on V,O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: V,O2,max= BMb (or FFMb) exp(a + (c × age) + (d × sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8% of the variance in V,O2,max. The parameters (± s.e.e., standard error of the estimate) for lnBM (0.563 ± 0.070), age (-0.0154 ± 0.0012), sex (0.242 ± 0.024) and the intercept (-1.09 ± 0.32) were all significant (P < 0.001). The FFM model explained 69.3% of the variance in V,O2,max, and the parameters (± s.e.e) lnFFM (0.772 ± 0.090), age (-0.0159 ± 0.0012) and the intercept (-1.57 ± 0.36) were significant (P < 0.001), while sex (0.077 +/, 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15% per decade (0.984 exp(age)) in V,O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in V,O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of V,O2,max across age is similar in older men and women. [source] A Study to Evaluate the Feasibility of an Aerobic Exercise Program in Patients With MigraineHEADACHE, Issue 4 2009Emma Varkey RPT Objectives., The aim of this study was to develop and evaluate an exercise program to improve maximum oxygen uptake (VO2 max) in untrained patients with migraine without making their migraines worse. Patients and methods., Twenty-six patients were studied at a headache clinic in Sweden. The exercise program, based on indoor cycling, was performed 3 times per week during 12 weeks. VO2 max, migraine status, side effects, and quality of life were evaluated. Results., VO2 max increased from 32.9 mL/kg/minute to 36.2 mL/kg/minute (P = .044). Quality of life increased and significant improvements in migraine status (attack frequency, symptom intensity, and intake of medicine) were seen. During the 12 weeks of exercise, on one occasion one patient had a migraine attack, which started immediately after training. No other side effects were reported. Conclusions., The evaluated exercise program was well tolerated by the patients and improved their VO2 max with no deterioration of migraine status. [source] Six-minute walk test in obese children and adolescents: Reproducibility and validity,PHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2009Gunilla Morinder Abstract Background and Purpose.,The six-minute walk test (6MWT) is increasingly used in clinical practice. The aims of this study were to determine the reproducibility of the 6MWT in obese children and adolescents, to describe walking capacity in this population and compare the results with values from normal-weight children (known group validity), and, finally, to describe the correlation between distance walked and estimated maximum oxygen uptake (VO2max).,Methods.,Reproducibility was determined by a test,retest design and known group validity by a comparative design. The 6MWT was first test,retested in 49 obese children (30 boys, 19 girls, 8,16 years, body mass index [BMI] 24.9,52.1,kg?m,2). Then, for validation, 250 obese children (126 boys, 124 girls, 8,16 years, BMI 23.2,57,kg/m2) and 97 normal-weight children (48 boys, 49 girls, 8,16 years, BMI 13.3,23.2,kg·m,2) performed the 6MWT. The obese children also performed a sub-maximal bicycle ergometry test.,Results.,In the test,retest, the obese children walked 571,m the first test and 57,m the second (p = 0.578). The measurement error (Sw) was 24,m, coefficient of variation (CV): 4.3% and the intraclass correlation (ICC1:1): 0.84. Repeatability was 68,m, and limits of agreement were +71 and ,65,m. In comparison mean (standard deviation), six-minute walk distance (6MWD) in the obese children was 571,m (65.5), and in the normal-weight children, 663,m (61.1) (p < 0.001). The correlation between 6MWD and estimated VO2max (r = 0.34) was low.,Conclusions.,The 6MWT showed good reproducibility and known group validity, and can be recommended for use in clinical practice in the studied population. To evaluate individual outcomes after intervention, the 6MWD needs to change by >68,m to be statistically significant. The 6MWD performed by obese children averaged 86% of the distance normal-weight children walked. In obese children, the correlation between 6MWD and estimated VO2max was low, hence the 6MWT cannot substitute a bicycle ergometry test. Copyright © 2008 John Wiley & Sons, Ltd. [source] Phosphocreatine degradation in type I and type II muscle fibres during submaximal exercise in man: effect of carbohydrate ingestionTHE JOURNAL OF PHYSIOLOGY, Issue 1 2001Kostas Tsintzas 1The aim of this study was to examine the effect of carbohydrate (CHO) ingestion on changes in ATP and phosphocreatine (PCr) concentrations in different muscle fibre types during prolonged running and relate those changes to the degree of glycogen depletion. 2Five male subjects performed two runs at 70 % maximum oxygen uptake (V,O2,max), 1 week apart. Each subject ingested 8 ml (kg body mass (BM)),1 of either a placebo (Con trial) or a 5.5 % CHO solution (CHO trial) immediately before each run and 2 ml (kg BM),1 every 20 min thereafter. In the Con trial, the subjects ran to exhaustion (97.0 ± 6.7 min). In the CHO trial, the run was terminated at the time coinciding with exhaustion in the Con trial. Muscle samples were obtained from the vastus lateralis before and after each trial. 3Carbohydrate ingestion did not affect ATP concentrations. However, it attenuated the decline in PCr concentration by 46 % in type I fibres (CHO: 20 ± 8 mmol (kg dry matter (DM)),1; Con: 34 ± 6 mmol (kg DM),1; P < 0.05) and by 36 % in type II fibres (CHO: 30 ± 5 mmol (kg DM),1; Con: 48 ± 6 mmol (kg DM),1; P < 0.05). 4A 56 % reduction in glycogen utilisation in type I fibres was observed in CHO compared with Con (117 ± 39 vs. 240 ± 32 mmol glucosyl units (kg DM),1, respectively; P < 0.01), but no difference was observed in type II fibres. 5It is proposed that CHO ingestion during exhaustive running attenuates the decline in oxidative ATP resynthesis in type I fibres, as indicated by sparing of both PCr and glycogen breakdown. The CHO-induced sparing of PCr, but not glycogen, in type II fibres may reflect differential recruitment and/or role of PCr between fibre types. [source] Six-minute walk test is a poor predictor of maximum oxygen uptake in childrenACTA PAEDIATRICA, Issue 7 2010T Takken No abstract is available for this article. [source] | |||||||||||||