Percentage Of Peak Oxygen Consumption Research Articles

Increasing Oxygen Uptake in Cross-Country Skiers by Speed Variation in Work Intervals.

Accumulated time at a high percentage of peak oxygen consumption (VO2peak) is important for improving performance in endurance athletes. The present study compared the acute physiological and perceived effects of performing high-intensity intervals with roller ski double poling containing work intervals with (1)fast start followed by decreasing speed (DEC), (2)systematic variation in exercise intensity (VAR), and (3)constant speed (CON). Ten well-trained cross-country skiers (double-poling VO2peak 69.6 [3.5]mL·min-1·kg-1) performed speed- and duration-matched DEC, VAR, and CON on 3 separate days in a randomized order (5 × 5-min work intervals and 3-min recovery). DEC and VAR led to longer time ≥90% VO2peak (P = .016 and P = .033, respectively) and higher mean %VO2peak (P = .036, and P = .009) compared with CON, with no differences between DEC and VAR (P = .930 and P = .759, respectively). VAR, DEC, and CON led to similar time ≥90% of peak heart rate (HRpeak), mean HR, mean breathing frequency, mean ventilation, and mean blood lactate concentration ([La-]). Furthermore, no differences between sessions were observed for perceptual responses, such as mean rate of perceived exertion, session rate of perceived exertion or pain score (all Ps > .147). In well-trained XC skiers, DEC and VAR led to longer time ≥90% of VO2peak compared with CON, without excessive perceptual effort, indicating that these intervals can be a good alternative for accumulating more time at a high percentage of VO2peak and at the same time mimicking the pronounced variation in exercise intensities experienced during XC-skiing competitions.

How Patients With Heart Failure Perform Daily Life Activities: An Innate Energy-Saving Strategy.

Cardiopulmonary exercise test and 6-minute walking test are frequently used tools to evaluate physical performance in heart failure (HF), but they do neither represent activities of daily living (ADLs) nor fully reproduce patients' symptoms. We assessed differences in task oxygen uptake, both as absolute value and as percentage of peak oxygen consumption (peakVO2), ventilation efficiency (VE/VCO2 ratio), and dyspnea intensity (Borg scale) in HF and healthy subjects during standard ADLs and other common physical actions. Healthy and HF subjects (ejection fraction <45%, stable conditions) underwent cardiopulmonary exercise test. All of them, carrying a wearable metabolic cart, performed a 6-minute walking test, two 4-minute treadmill exercises (at 2 and 3 km/h), and ADLs: ADL1 (getting dressed), ADL2 (folding 8 towels), ADL3 (putting away 6 bottles), ADL4 (making a bed), ADL5 (sweeping the floor for 4 minutes), ADL6 (climbing 1 flight of stairs carrying a load). Sixty patients with HF (age 65.2±12.1 years; ejection fraction 30.4±6.7%, peakVO2 14.2±4.0 mL/[min·kg]) and 40 healthy volunteers (58.9±8.2 years, peakVO2 28.1±7.4 mL/[min·kg]) were enrolled. For each exercise, patients showed higher VE/VCO2 ratio, percentage of peakVO2, and Borg scale value than controls, while absolute values of task oxygen uptake and exercise duration were lower and higher, respectively, in all activities, except for treadmill (fixed execution time and intensity). Differently from Borg Scale data, metabolic values and exercise time length changed in parallel with HF severity, except for ADL duration in very short (ADL3) and composite (ADL1) activities. Borg scale values correlated with percentage of peakVO2. During ADLs, patients self-regulated activities in parallel with HF severity by decreasing intensity (VO2) and prolonging the effort.

Effects of an Upper-Body Training Program Involving Resistance Exercise and High-Intensity Arm Cranking on Peak Handcycling Performance and Wheelchair Propulsion Efficiency in Able-Bodied Men.

Chaikhot, D, Reed, K, Petroongrad, W, Athanasiou, F, van Kooten, D, and Hettinga, FJ. Effects of an upper-body training program involving resistance exercise and high-intensity arm cranking on peak handcycling performance and wheelchair propulsion efficiency in able-bodied men. J Strength Cond Res 34(8): 2267-2275, 2020-The aim of this study was to determine the training effects of an upper-body training program involving resistance exercise and high-intensity arm cranking on peak handcycling performance, propulsion efficiency, and biomechanical characteristics of wheelchair propulsion in able-bodied men. The training group (n = 10) received a 4-week upper-body resistance training (RT), 70% of 1 repetition maximum, 3 sets of 10 repetitions, 8 exercise stations, 2 times per week, combined with high-intensity interval training (HIIT) 2 times per week. High-intensity interval training consisted of arm-crank exercise, 7 intervals of 2 minutes at 80-90% of peak heart rate (HRpeak) with 2-minute active rest at 50-60% of HRpeak. The control group (n = 10) received no training. Both groups performed a preincremental and postincremental handcycling test until volitional exhaustion to evaluate fitness and a 4-minute submaximal wheelchair propulsion test at comfortable speed (CS), 125 and 145% of CS, to evaluate gross mechanical efficiency (GE), fraction of effective force (FEF), percentage of peak oxygen consumption (% V[Combining Dot Above]O2peak), and propulsion characteristics. Repeated-measures analysis of variance was performed (p < 0.05). Training resulted in a 28.2 ± 16.5% increase in peak power output, 13.3 ± 7.5% increase in V[Combining Dot Above]O2peak, 5.6 ± 0.9% increase in HRpeak, and 3.8 ± 1.5% decrease in HRrest. No training effects on FEF, GE, % V[Combining Dot Above]O2peak, and push characteristics were identified. In conclusion, the combined RT and arm-cranking HIIT improved fitness. However, it seems that this training did not result in improvements in propulsion efficiency and push characteristics. Additional wheelchair skill training may be needed to fully benefit from this advantage in daily life propulsion.

Serial Analysis of Cardiopulmonary Fitness and Echocardiography in Patients with Fabry Disease Undergoing Enzyme Replacement Therapy.

ObjectiveFabry disease, a rare X-linked disorder, can lead to exercise intolerance. In Taiwan, the cardiac variant of Fabry disease has a significantly higher prevalence than the classic variant. The cardiac variant of Fabry disease primarily involves the heart. Enzyme replacement therapy has been used to treat both variants. We aimed to study the impact of enzyme replacement therapy on exercise and cardiac structures between the classic (CL-FD) and cardiac variant (CV-FD) Fabry disease.Design and methodsRetrospective analysis of 2 groups of patients with Fabry disease (5 patients with the classic variant and 5 with the cardiac variant), who were undergoing enzyme replacement therapy. Patients were assessed annually for 3 years using symptom-limited cycle ergometry and echocardiography.ResultsSubjects were 5 women, mean age 53 (standard deviation (SD) 14.05) years with CL-FD Fabry disease, and 5 men, mean age 65 (SD 2.35) years with CV-FD. The percentage of peak oxygen consumption to predicted value for all included patients was significantly lower (78.78% (SD 12.72)) than 100%. Annual serial measurement showed that peak metabolic equivalent and percentage of peak oxygen consumptiondecreased significantly over a period of 3 years in patients with CV-FD (p = 0.002, and p =0.004, respectively), but not in those with CL-FD. There were no significant changes in annual serial measurements of left ventricular mass or interventricular septal thickness in patients with either variant of Fabry disease over a period of 3 years.ConclusionPeak exercise capacity of the patients with Fabry disease was lower than that of normal peers. Peak exercise capacity decreased over timeLAY ABSTRACTPatients with classic or cardiac variants of Fabry disease have lower exercise capacity than their healthy peers. It is recommended that patients commence enzyme replacement therapy at an early stage in order to improve clinical outcomes. This study examined the effects of enzyme replacement therapy on exercise capacity and the structure of the heart in 10 patients with Fabry disease who were undergoing enzyme replacement therapy. Measurements were taken each year for 3 consecutive years. No significant differences were found in the structure of the heart (left ventricular mass or interventricular septal thickness) between patients with these 2 types of Fabry disease. Peak exercise capacity decreased over time in patients with cardiac variant Fabry disease, but remained the same in patients with classic variant Fabry disease in patients withCV-FD, but remained the same in patients with CL-FD.

Increasing Oxygen Uptake in Well-Trained Cross-Country Skiers During Work Intervals With a Fast Start.

Accumulated time at a high percentage of peak oxygen consumption (VO2peak) is important for improving performance in endurance athletes. The present study compared the acute effect of a roller-ski skating session containing work intervals with a fast start followed by decreasing speed (DEC) with a traditional session where the work intervals had a constant speed (similar to the mean speed of DEC; TRAD) on physiological responses, rating of perceived exertion, and leg press peak power. A total of 11 well-trained cross-country skiers performed DEC and TRAD in a randomized order (5 × 5-min work intervals, 3-min relief). Each 5-minute work interval in the DEC protocol started with 1.5 minutes at 100% of maximal aerobic speed followed by 3.5 minutes at 85% of maximal aerobic speed, whereas the TRAD protocol had a constant speed at 90% of maximal aerobic speed. DEC induced a higher VO2 than TRAD, measured as both peak and average of all work intervals during the session (98.2% [2.1%] vs 95.4% [3.1%] VO2peak, respectively, and 87.6% [1.9%] vs 86.1% [3.2%] VO2peak, respectively) with a lower mean rating of perceived exertion after DEC than TRAD (16.1 [1.0] vs 16.5 [0.7], respectively) (all P < .05). There were no differences between sessions for mean heart rate, blood lactate concentration, or leg press peak power. DEC induced a higher mean VO2 and a lower rating of perceived exertion than TRAD, despite similar mean speed, indicating that DEC can be a good strategy for interval sessions aiming to accumulate more time at a high percentage of VO2peak.

From accelerometer output to physical activity intensities in breast cancer patients

ObjectivesWe aimed to investigate accelerometer output corresponding to physical activity intensity cut-points based on percentage of peak oxygen consumption (%VO2peak) and Metabolic Equivalent of Task (MET) value in women treated for breast cancer. DesignLaboratory study. MethodsFifty female patients shortly after completion of treatment for breast cancer were included. VO2peak was determined during a cardiopulmonary exercise test. Subsequently, patients performed ten activities with different intensities while wearing an accelerometer on the right hip and a mobile oxycon to assess oxygen consumption. We studied the relationship between energy expenditure (expressed as %VO2peak and MET-value) and accelerometer output (in counts per minute (cpm)) with linear regression analyses. We determined accelerometer output corresponding to physical activity intensity cut-points (40% and 60%VO2peak; 3 and 6 MET) using regression equations. ResultsVO2peak was 22.4mL/kg/min (SD 5.2) and resting metabolic rate was 3.1mL/kg/min (SD 0.6). Accelerometer output corresponding to the cut-points for moderate (40% VO2peak) and vigorous intensity (60% VO2peak) were 1123 and 1911, respectively. The analyses based on MET-values resulted in accelerometer output of 1189cpm for the moderate (3 MET) and 2768 cpm for the vigorous intensity cut-point (6 MET). ConclusionsAccelerometer outputs for moderate and vigorous intensity physical activity were lower than commonly used cut-points (i.e. 1952 and 5724 cpm), irrespective of the method used to express energy expenditure (%VO2peak versus MET-value). Thus, categorizing physical activity intensities based on general-population cut-points, may underestimate physical activity intensities for women treated for breast cancer.

Greater fluid loss does not fully explain the divergent hemodynamic balance mediating postexercise hypotension in endurance-trained men.

Following exercise, mean arterial pressure (MAP) is reduced ~5-10 mmHg from preexercise baseline. In nonendurance-trained males, postexercise hypotension results from peripheral vasodilation not offset by increased cardiac output (CO). By contrast, postexercise hypotension occurs through a reduction in CO from preexercise baseline in endurance-trained males. The reason(s) explaining these divergent responses remain unknown. Exercise at fixed percentage of peak oxygen consumption (V̇o2peak) is associated with a greater rate of metabolic heat production in trained individuals and therefore elevated sweat rates, both when compared with untrained individuals. We hypothesized that greater fluid loss would explain the postexercise reduction in CO of endurance-trained males. Twelve endurance-trained males (Trained: V̇o2peak, 64 ± 5 ml O2·kg-1·min-1) cycled for 60 min at 60% V̇o2peak (Trained60%). On separate days, 12 nonendurance trained males (Untrained: V̇o2peak, 49 ± 3 ml O2·kg-1·min-1) cycled at 1) 60% V̇o2peak (Untrained60%), and 2) a rate of heat production equivalent to that achieved by the Trained group (UntrainedMatched). Fluid loss was similar between Trained60% (-1.32 ± 0.20 kg) and UntrainedMatched (-1.32 ± 0.23 kg; P = 0.99) but was greater in these conditions relative to Untrained60% (-0.95 ± 0.11 kg; both P < 0.01). During the final 30 min of postexercise supine recovery, MAP was similarly reduced by 5 ± 2 mmHg in all three conditions ( P = 0.91). The reduction in MAP was mediated by a 0.5 ± 0.3 l/min reduction in CO from baseline in Trained60% ( P = 0.01). In contrast, CO returned to baseline following exercise during UntrainedMatched and Untrained60% (both P ≥ 0.30). These data demonstrate that greater fluid loss does not fully explain the divergent postexercise hemodynamic responses observed in trained relative to untrained males. NEW & NOTEWORTHY Even when matched for exercise-induced fluid loss, cardiac output was decreased in trained males but returned to baseline following exercise in their untrained counterparts. However, as per our hypothesis, reductions in stroke volume were similar between groups. This suggests that exercise-induced fluid loss is an important determinant of the stroke volume response during recovery but factors affecting heart rate such as exercise intensity and/or heat stress are also important determinants of postexercise hemodynamics.

Autonomic and cardio-respiratory responses to exercise in Brugada Syndrome patients

BackgroundImbalances of the autonomic nervous (ANS), the cardiovascular system, and ionics might contribute to the manifestation of The Brugada Syndrome (BrS). Thus, this study has aimed to investigate the cardio-respiratory fitness and the responses of the ANS both at rest and during a sub-maximal exercise stress test, in BrS patients and in gender-matched and age-matched healthy sedentary controls. MethodsEleven BrS patients and 23 healthy controls were recruited in Khon Kaen, Thailand. They performed an exercise test on a cycle ergometer, and during the exercise, expired gas samples and electrocardiograms were collected. Blood glucose and electrolyte concentrations were analyzed before and after exercise. Then the heart rate variability (HRV) and the heart rate recovery (HRR) were analyzed from the electrocardiograms. ResultsThe BrS patients showed a higher parasympathetic activation during exercise recovery than baseline. They had a smaller level of sympathetic activation during the period of exercise recovery than the controls did. They also showed a significantly lower peak HR, HRR, and peak oxygen consumption than the controls (p<0.05). All subjects had a significantly lower percentage of peak oxygen consumption and respiratory exchange ratio during low-intensity (p<0.01) and moderate-intensity (p<0.05) exercise than during high-intensity exercise. The BrS patients had mild hyperkalemia which is reduced according to the exercise. ConclusionThai BrS patients had a more rapid rate of restoration of the parasympathetic and smaller level of sympathetic activation after exercise. They had mild hyperkalemia which is reduced according to the exercise. Furthermore, they exhibited impaired cardio-respiratory fitness.

The influence of thermal factors on postexercise haemodynamics in trained and untrained men

Previous work suggests that the cardiovascular mechanisms underlying the postexercise reduction in mean arterial pressure (MAP) differ between exercise‐trained and untrained men. However, these studies compared responses based on the same percentage of peak oxygen consumption (VO2peak) resulting in different rates of heat production during exercise. Thus, we evaluated if exercise‐induced differences in the requirement for heat loss, and therefore sweat loss, may influence postexercise haemodynamics. Twelve trained (T60) (VO2peak, 64 ± 4 mL/kg/min) and twelve untrained (UT60) (VO2peak, 49 ± 3 mL/kg/min) males, individually matched for body surface area, cycled for 60 min at 60% of VO2peak­. On a separate day the untrained group performed an additional 60 min of cycling at the same heat production as their trained match in T60 (UTMatch). Sweat loss was assessed by change in body weight (ΔBW). MAP and cardiac output (CO) were measured at baseline and every 10 min during 60 min of postexercise recovery. ΔBW was similar between T60 and UT­Match (T60: ‐1.32 ± 0.36 kg; UTMatch: ‐1.32 ± 0.32 kg) and greater in these conditions relative to UT60 (‐0.95 ± 0.13 kg; both P &lt; 0.05). Further, MAP was ~5 mmHg below baseline following 20 min of recovery in each condition (all P &lt; 0.05). Postexercise CO was ~7% below baseline in T60 (P &lt; 0.05) whereas it was elevated relative to T60 (both P &lt; 0.05) and similar to baseline (both P &gt; 0.05) in UT60 and UTMatch. We show that the differing mechanisms between trained and untrained males underlying the postexercise reduction in MAP are not the result of differences in exercise‐induced heat load and therefore fluid loss. Support: Natural Sciences and Engineering Research Council of Canada.

Interest of an Individualized Score among Children Using the OMNI Cycle Scale

The study purposes were 1) to study the differences between perceived exertion measured by a generic (/10) or an individualized (/max value obtained during the test) score on the OMNI cycle scale (OMNImax and OMNI10) and the actual effort (peak oxygen consumption) at different stages of a maximal cycling test in a group of children age 8 to 10 yr old and 2) to assess whether the concordance between perceived exertion and actual effort differs according to body mass status or physical activity level. A total of 477 children from the QUebec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort performed a progressive maximal test on a cycling ergometer. Oxygen consumption was continuously measured during the test. Perceived exertion was measured at the end of each stage, at exhaustion, and during recovery using the OMNI cycle scale. Percentage of peak oxygen consumption was compared with %OMNI10 and %OMNImax; two-way ANOVA was conducted to detect the differences between the physiologic and subjective indicators of exercise intensity according to body mass status and physical activity levels of children. At each stage of the test, except during recovery, children perceived their effort to be lower than the actual intensity level. This lower scoring of exercise intensity is more important when using OMNI10 than OMNImax. No differences in body mass status or physical activity level were observed. It is better to consider the OMNI score relative to the maximal score obtained (OMNImax) from the children to reflect the actual physiological effort (oxygen consumption). The association between the effort performed and the OMNI cycle scale score is independent of body mass status and physical activity level of the child.

Substrate oxidation during incremental arm and leg exercise in men and women matched for ventilatory threshold

The aim of this study was to determine the variations in substrate utilization between men and women matched for ventilatory threshold (T vent) during incremental arm cranking and leg cycling exercise at 70, 85, 100 and 115% of the mode-specific T vent. Recreationally active men (n = 12) and women (n = 10) with similar values for percentage of peak oxygen consumption at T vent participated in the study. Ventilatory equivalence, excess CO2 and modified V-slope methods were used concurrently to determine T vent. The participants performed 5 min of exercise at each of 70, 85, 100 and 115% T vent during both arm cranking and leg cycling exercise. The females were tested during the early follicular phase for all trials. A two-way mixed-design analysis of variance was performed to test for differences between the sexes. When carbohydrate and fat oxidation were expressed relative to total fat-free mass, carbohydrate oxidation during arm cranking and leg cycling was significantly higher in men than women at each percentage of T vent. In contrast, women showed significantly higher fat oxidation across intensities during both arm cranking and leg cycling. Our results suggest that when substrate utilization is expressed relative to total fat-free mass, women appear to maintain a higher rate of fat and lower rate of carbohydrate oxidation than men during both incremental arm cranking and leg cycling exercise relative to T vent.

Exercise and Cognitive Performance in Chronic Fatigue Syndrome

To determine the effect of submaximal steady-state exercise on cognitive performance in patients with chronic fatigue syndrome (CFS) alone, CFS with comorbid fibromyalgia FM (CFS + FM), and sedentary healthy controls (CON). Twenty CFS-only patients, 19 CFS + FM, and 26 CON completed a battery of cognitive tests designed to assess speed of information processing, variability, and efficiency. Tests were performed at baseline, immediately before, and twice following 25 min of either cycle ergometry set at 40% of peak oxygen capacity or quiet rest. There were no group differences in average percentage of peak oxygen consumption during exercise (CFS = 45%; CFS + FM = 47%; Control = 43%: P = 0.2). There were no significant effects of acute exercise on cognitive performance for any group. At baseline, one-way ANOVA indicated that CFS patients displayed deficits in speed of processing, performance variability, and task efficiency during several cognitive tests compared with healthy controls. However, the CFS + FM patients were not different than controls. Repeated measures ANOVA indicated that across all tests (pre- and postexercise) CFS, but not CFS + FM, were significantly less consistent (F2,59 = 3.7, P = 0.03) and less efficient (F2,59 = 4.6, P = 0.01) than controls. CFS patients without comorbid FM exhibit subtle cognitive deficits in terms of speed, consistency, and efficiency that are not improved or exacerbated by light exercise. Importantly, our data suggest that CFS + FM patients do not exhibit cognitive deficits either pre- or postexercise. These results highlight the importance of disease heterogeneity in studies determining acute exercise and cognitive function in CFS.

Maximal oxygen uptake during cycling is reduced in moving environments; consequences for motion-induced fatigue

In previous studies on physical fatigue during simulated ship movements, the apparent exhaustion of subjects after experimentation suggested that the traditional index of physical workload, oxygen consumption expressed as the percentage of peak oxygen consumption ([Vdot]O2-peak) measured in a separate graded exercise test (GXT), underestimates workload in a moving environment. In these studies, the GXT was carried out in a stationary environment, as is standard practice. To explain the underestimation, it was hypothesized that [Vdot]O2-peak might have been less if the GXT had been carried out in the moving environment. This paper reports on three experimental tests of this hypothesis, performed with a ship motion simulator and aboard a ship at sea. In all three experiments, [Vdot]O2-peak was indeed significantly reduced when the GXT was carried out in the moving environment. Theoretical reasons for this phenomenon are discussed and investigated, but a clear explanation is still lacking.

The Effect of Aging on the Lactate Threshold in Untrained Men

Thirty-three men (age 26–55 years) who did not exercise regularly were exercised to exhaustion using an incremental treadmill protocol. Blood lactate concentration was measured to identify lactate threshold (LT, oxygen consumption at which blood lactate concentration begins to systematically increase). The correlation coefficient for LT (ml · kg−1 · min−1) with age was not significant, but when LT was expressed as a percentage of peak oxygen consumption (VO2 peak), the correlation was r = +.69 (p &lt; .01). This was despite a lack of significant correlation between age and VO2 peak (r = −.33). The correlation between reserve capacity (the difference between VO2 peak and LT) and age was r = −.73 (p &lt; .01 ), and reserve capacity decreased at a rate of 3.1 ml · kg−1 · min−1 per decade. It was concluded that the percentage of VO2 peak at which LT occurs increases progressively with age, with a resultant decrease in reserve capacity.

Stroke volume increases by similar mechanisms during upright exercise in normal men and women

To define the effects of gender on stroke volume control during upright exercise in normal subjects, we examined central hemodynamics in 34 men and 27 women during staged bicycle ergometry. Central hemodynamics were assessed by right-sided cardiac catheterization and simultaneous radionuclide angiography. Left ventricular end-diastolic and end-systolic volumes were calculated from the stroke volume (by direct Fick) and the corresponding left ventricular ejection fraction. Men were larger than women (1.85 ± 0.11 vs 1.65 ± 0.13 m 2, p < 0.001) but groups were matched for age (39 ± 12 vs 36 ± 9 years, p = 0.27). Oxygen consumption at peak exercise was higher in men than in women (2.51 ± 0.50 vs 1.74 ± 0.30 liters/min, p < 0.001) but was not different when adjusted for body weight (31.5 ± 8.1 vs 28.4 ± 6.4 ml/kg/min, p = 0.14), indicating similar levels of overall fitness in the 2 groups. At rest and during submaximal and maximal exercise, stroke volume and left ventricular end-diastolic and end-systolic volumes were higher in men than in women, but there were no intergroup differences in stroke volume index, left ventricular ejection fraction, and left ventricular end-diastolic or end-systolic volume indexes. Comparison of derived regression equations of cardiac index, stroke volume index and left ventricular end-diastolic and end-systolic volume indexes revealed no differences in the time course or magnitude of changes with respect to oxygen consumption, expressed as percentage of peak oxygen consumption, in the 2 groups. The major increase in left ventricular end-diastolic volume from upright rest in both men and women occurred during early exercise and accounted for most of the increase in stroke volume with relatively small increases in pulmonary wedge pressure. With moderate to intense exercise, stroke volume was maintained because of decreases in left ventricular end-systolic volume, as left ventricular end-diastolic volume did not change or decreased slightly from 50 to 100% of peak oxygen consumption in both men and women. Our data indicate that in normal subjects, gender, independent of body size and physical fitness, is not an important determinant of cardiac output or left ventricular volume response to upright exercise.