Peak Aerobic Exercise Research Articles

Acute Respiratory Muscle Fatigue in Patients with Obesity Following Peak Aerobic Exercise

IntroductionRespiratory muscle (RM) performance has been theorized to contribute to exercise‐induced dyspnea, exercise intolerance, and low exercise capacity in patients with obesity. However, the impact of acute impairments in RM performance on exercise intolerance and exercise capacity in patients with obesity remains uncertain. We hypothesized, that following peak aerobic exercise, impairments in RM performance would be observed in patients with obesity.MethodsWe prospectively recruited 7 participants (recruitment is ongoing; 1 male, 6 female, Age: 42 ± 9 yrs; BMI: 47.7 ± 5.9 kg/m2; Waist Circumference: 126 ± 12.04 cm; Body Fat [%]: 50.91 ± 3.6). Diaphragm Thickness at expiration and Thickening Ratio (thickness at end‐inspiration – thickness at end‐expiration)/thickness at end‐expiration) were assessed via B‐mode ultrasound at the right 8th intercostal space while patients were in a semi‐recumbent position elevated 30 degrees from supine. Participants performed a cardiopulmonary exercise test (CPET) using a ramp treadmill protocol to peak exercise capacity. Measurements of RM performance were measured at baseline and repeated at 0‐minutes and 5‐minutes following CPET; which included Maximal Inspiratory Pressure (MIP), Sustained Maximal Inspiratory Pressure (SMIP), Inspiratory Duration (ID), Slope of the SMIP Plot (SMIP Slope), and Maximal Expiratory Pressure (MEP). Two‐Sided Paired T‐Tests were used to compare RM performance data before and after testing; statistical significance was set at p<0.05.ResultsMean CPET Results: VO2peak: 19.37 ± 2.4 mL/kg/min; RER: 1.01 ± 0.11; Age Predicted Heart Rate Max [%] 87.57 ± 0.14; Ventilatory Reserve [%] 25.25 ± 18.32; VE/VCO2 Slope: 28.84 ± 4.50. Diaphragm Thickness: 2.8 ± 0.24 mm and Thickening Ratio: [%]: 75.47 ± 25.97. When comparing Baseline to 0‐minues following CPET significant reductions in MIP, SMIP, and MEP were observed: MIP (94.57 ± 25.01 cmH2O vs. 72.29 ± 22.09 cmH2O p = 0.02); SMIP (524.14 ± 198.85 PTU vs. 418.43 PTU p = 0.04); MEP (73.71 ± 17.10 cmH2O vs. 62.29 ± 12.83 cmH2O p= 0.02). A reduction in ID (10.6 ± 2.30 vs 8.99 sec p= 0.06) and an increase in SMIP Slope (9.2 ± 3.39 vs. 9.74 ± 3.30 p= 0.74) were observed at 0‐minutes following CPET compared to baseline but were not significant. At 5‐minutes following CPET, significant reductions in MIP (67.3 cmH2O ± 12.6 p= 0.01) and MEP (62.57 ± 14.47 cm H2O p= 0.01) were observed but not for other measures of RM performance.ConclusionOur results suggest that patients with obesity demonstrate significant reductions in RM performance following peak aerobic exercise which may persist even after recovery. Interestingly, at baseline, the patients with obesity in this study demonstrated relatively normal RM performance, diaphragm thickness and thickening ratio. Acute fatigue of the respiratory muscles may contribute to the exercise induced dyspnea, exercise intolerance and low exercise capacity observed in patients with obesity.

Relationship between cardiorespiratory fitness and preoperative evaluation findings in patients with morbid obesity undergoing sleeve gastrectomy: A cross-sectional study.

Evaluating various parameters, including preoperative cardiorespiratory fitness markers, is critical for patients with morbid obesity. Also, clinicians should prescribe suitable exercise and lifestyle guideline based on the tested parameters. Therefore, we investigated cardiorespiratory fitness and its correlation with preoperative evaluation in patients with morbid obesity scheduled for laparoscopic sleeve gastrectomy.A retrospective cross-sectional study was conducted with 38 patients (13 men and 25 women; mean age, 34.9 ± 10.9 years) scheduled for laparoscopic sleeve gastrectomy. Cardiopulmonary exercise stress tests were also performed. Measured cardiopulmonary responses included peak values of oxygen consumption (VO2), metabolic equivalents (METs), respiratory exchange ratio, heart rate (HR), and rate pressure product. Body composition variables were analyzed using bioimpedance analysis, laboratory parameters (hemoglobin A1c, lipid profile, inflammatory markers), and comorbidities. In addition, self-reported questionnaires were administered, including the Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HDRS), Short-Form Health Survey (SF-36), and Moorehead-Ardelt Quality of Life Questionnaire (MAQOL).The average body mass index (BMI) and percent body fat were 39.8 ± 5.7 kg/m−2 and 46.2 ± 6.1%, respectively. The VO2peak/kg, METs, RERpeak, HRpeak, RPPpeak, age-predicted HR percentage, and VO2peak percentage were 18.6 ± 3.8 mL/min−1/kg−1, 5.3 ± 1.1, 1.1 ± 0.1, 158.5 ± 19.8, 32,414.4 ± 6,695.8 mm Hg/min−1, 85.2 ± 8.8%, and 76.1 ± 14.8%, respectively. BMI (P = .026), percent body fat (P = .001), HRpeak (P = .018), erythrocyte sedimentation rate (P = .007), total BDI (P = .043), HDRS (P = .025), SF-36 (P = .006), and MAQOL (P = .007) scores were significantly associated with VO2peak/kg. Body fat percentage (P < .001) and total SF-36 score (P < .001) remained significant in the multiple linear regression analysis.Various cardiorespiratory fitness markers were investigated in patients with morbid obesity who underwent the sleeve gastrectomy. Peak aerobic exercise capacity was significantly associated with preoperative parameters such as body fat composition and self-reported quality of life in these patients. These results could be utilized for preoperative and/or postoperative exercise strategies in patients with morbid obesity scheduled for laparoscopic sleeve gastrectomy.

Prolonged Elevation of Arterial Stiffness Following Peak Aerobic Exercise in Individuals With Chronic Stroke.

BackgroundStroke is a highly disabling condition and is the second leading cause of death globally. Engaging in aerobic exercise is important for the prevention of a recurrent stroke through improving markers of cardiovascular health such as blood pressure and arterial stiffness. While higher intensities of aerobic exercise generally elicit greater cardioprotective effects, little is known about the acute cardiovascular effects of a single session of high intensity aerobic exercise in people with stroke. The objective of this study was to model the recovery of arterial stiffness (carotid-femoral pulse wave velocity, cfPWV), heart rate and blood pressure following peak intensity aerobic exercise in individuals with chronic stroke.MethodsTen participants with chronic stroke (mean ± SD age = 56.9 ± 11.8 years, median [IQR] years post-stroke = 2.9 [1.9]) performed a symptom-limited cardiopulmonary exercise test (CPET) on a recumbent stepper. Before the CPET, resting cfPWV, heart rate and blood pressure were measured. Immediately following the CPET, all outcomes were measured again continuously for 20 min to use all available observations (n = 245 observations) and capture any potential non-linear changes. Mixed model analyses were then applied to model post-exercise changes of cfPWV, heart rate and blood pressure.ResultsCarotid-femoral pulse wave velocity was increased from rest following the CPET (9.0 ± 0.53 to 9.9 ± 0.52 m/s, p < 0.001) and remained elevated for 20 min into post-exercise recovery, independent of heart rate (p = 0.001). Heart rate also increased from baseline (71.2 ± 3.2 to 77.4 ± 3.1 bpm, p < 0.001) and remained elevated for 10 min post-exercise (p < 0.001). Finger systolic blood pressure was reduced from rest (117.3 ± 4.7 to 111.8 ± 4.6 mmHg, p < 0.001) and remained reduced for 15 min after exercise (p < 0.001). There were no significant differences in finger diastolic or mean arterial pressures from rest.ConclusionThis was the first study to capture continuous changes in cfPWV following peak aerobic exercise in any clinical population. The present study revealed that cfPWV is elevated for 20 min after peak aerobic exercise in individuals with stroke, which was independent of heart rate. These findings suggest there may be autonomic imbalances in large arteries following peak intensity aerobic exercise in individuals with stroke.

Investigation of the Relationship Between Peak Vertical Accelerations and Aerobic Exercise Intensity During Graded Walking and Running in Postmenopausal Women

How exercise intensity targets, calibrated according to oxygen consumption, relate to vertical impacts during weight-bearing exercise is currently unknown. The authors investigated the relationship between vertical peaks (VPs) and metabolic equivalents (METs) of oxygen consumption in 82 women during walking and running. The magnitude of VPs, measured using a hip-worn triaxial accelerometer, was derived from recommended aerobic exercise intensity targets. VPs were 0.63 ± 0.18g at the lower recommended absolute exercise intensity target (3 METs) but >1.5g at the upper end of moderate-intensity activities (1.90 ± 1.13g at 6 METs). Multilevel linear regression analyses identified speed and type of locomotion as the strongest independent predictors of VPs, explaining 54% and 11% of variance, respectively. The authors conclude that, in contrast to lower intensities, exercising close to or above the 6-MET threshold generates VPs of osteogenic potential, suggesting this could provide simultaneous benefits to decrease all-cause mortality and osteoporosis risk.

Periodicity, time constants of drainage, and the mechanical determinants of peak cardiac output during exercise.

To analyze mechanical adaptations that must occur in the cardiovascular system to reach the high cardiac outputs known to occur at peak aerobic performance, we adapted a computational model of the circulation by adding a second parallel venous compartment as proposed by August Krogh in 1912. One venous compartment has a large compliance and slow time constant of emptying; it is representative of the splanchnic circulation. The other has a low compliance and fast time constant of emptying and is representative of muscle beds. Fractional distribution between the two compartments is an important determinant of cardiac output. Parameters in the model were based on values from animal and human studies normalized to a 70 kg male. The baseline cardiac output was set at 5 L/min, and we aimed for 25 L/min at peak exercise with a fractional flow to the peripheral-muscle region of 90%. Finally, we added the equivalent of a muscle pump. Adjustments in circuit and cardiac parameters alone increased cardiac output to only 15.6 L/min because volume accumulated in the muscle compartment and limited a higher cardiac output. Addition of muscle contractions decompressed the muscle region and allowed cardiac output to increase to 23.4 L/min. The pulsatility of blood flow imposes important constraints on the adaptations of cardiac and circulatory functions because it fixes the times for filling and emptying. Flow is further limited by the limits of cardiac filling on each beat. Muscle contractions play a key role by decompressing volume that would otherwise accumulate in the muscle vasculature and by decreasing the time for stroke return to the right ventricle.NEW & NOTEWORTHY We used a computational model of the circulation and previous human and animal data to model mechanical changes in the heart and circulation that are needed to reach the known high cardiac output at peak aerobic exercise. Key points are that time constants of drainage of circulatory compartments put limits on peak flow in a pulsatile system. Muscle contractions increase the rate of return to the heart and by doing so prevent accumulation of volume in the muscle compartment and greatly increase circulatory capacity.

Skeletal Muscle Dysfunction and Exercise Intolerance in Children Treated with Haematopoietic Stem Cell Transplant-A Pilot Feasibility Study.

Haematopoietic stem cell transplant (HSCT) is an intensive therapy for some pediatric hematological illnesses. Survivors are at risk for adverse effects including exercise intolerance. Peripheral tissue dysfunction may contribute to exercise intolerance; therefore, we examined the feasibility of a magnetic resonance spectroscopy (MRS) protocol to evaluate skeletal muscle metabolism in children post-HSCT. We measured demographic characteristics, aerobic exercise capacity (YMCA protocol), and skeletal muscle function in response to exercise (MRS; Siemens 3T MRI) in five children post-allogeneic HSCT and five age/body mass index-matched healthy controls (HCs). The mean age (± standard deviation) of the HSCT group and HC group were 11 ± 1.2 and 12.8 ± 2.4 years, respectively. Children post-HSCT had a lower peak aerobic exercise capacity compared to HCs (27.8 ± 3.4 vs. 40.3 ± 8.1 mL kg−1 min−1, respectively; p = 0.015). Exercise MRS testing protocols were successfully completed by all HSCT and HC participants; however, MRS-derived skeletal muscle metabolism variables were not different between the two groups. In conclusion, the use of exercise protocols in conjunction with MRS to assess peripheral skeletal muscle metabolism was achievable in children post-HSCT. In the future, larger studies should determine if skeletal muscle function is associated with exercise capacity in children post-HSCT.

Relationship between wheelchair skills scores and peak aerobic exercise capacity of manual wheelchair users with spinal cord injury: a cross-sectional study

Purpose: Although both wheelchair skills and fitness are important and probably inter-related, the extent and nature of the relationship between them are not well understood. The objective of this study was to test the hypothesis that there are significant relationships between wheelchair skills scores and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Materials and methods: We studied 26 participants, recording Wheelchair Skills Test Questionnaire scores and peak power output from graded aerobic wheelchair exercise testing on a motorized treadmill.Results: The median Wheelchair Skills Test Questionnaire capacity, confidence, and performance scores were 83.3%, 81.5%, and 76.7% and the median peak power output was 58.2 W. On regression analysis, there were significant relationships between the total Wheelchair Skills Test Questionnaire capacity, confidence, and performance scores and peak power output (R2 0.270–0.709, odds ratios 1.043–1.150, p < 0.05).Conclusions: Significant relationships exist between the wheelchair skills capacity, confidence, and performance scores and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury. These findings suggest that both wheelchair skills training and exercise training may be useful during the rehabilitation of people with spinal cord injury.Implications for rehabilitationModerate positive relationships exist between wheelchair skills capacity and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Moderate positive relationships exist between wheelchair skills confidence and the peak exercise capacity of community-dwelling manual wheelchair users with spinal cord injury.Although further research is needed, these findings suggest that clinicians should address both wheelchair skills training and exercise training during the rehabilitation of people with spinal cord injury and not assume that either alone is sufficient.

Effect of Losartan on Right Ventricular Dysfunction: Results From the Double-Blind, Randomized REDEFINE Trial (Right Ventricular Dysfunction in Tetralogy of Fallot: Inhibition of the Renin-Angiotensin-Aldosterone System) in Adults With Repaired Tetralogy of Fallot.

The effect of angiotensin II receptor blockers on right ventricular (RV) function is still unknown. Angiotensin II receptor blockers are beneficial in patients with acquired left ventricular dysfunction, and recent findings have suggested a favorable effect in symptomatic patients with systemic RV dysfunction. The current study aimed to determine the effect of losartan, an angiotensin II receptor blocker, on subpulmonary RV dysfunction in adults after repaired tetralogy of Fallot. The REDEFINE trial (Right Ventricular Dysfunction in Tetralogy of Fallot: Inhibition of the Renin-Angiotensin-Aldosterone System) is an investigator-initiated, multicenter, prospective, 1:1 randomized, double-blind, placebo-controlled study. Adults with repaired tetralogy of Fallot and RV dysfunction (RV ejection fraction [EF] <50%) but without severe valvular dysfunction were eligible. Patients were randomly assigned between losartan (150 mg daily) and placebo with target treatment duration between 18 and 24 months. The primary outcome was RV EF change, determined by cardiovascular MRI in intention-to-treat analysis. Of 95 included patients, 47 patients received 150 mg losartan daily (age, 38.0±12.4 years; 74% male), and 48 patients received placebo (age, 40.6±11.4 years; 63% male). Overall, RV EF did not change in patients allocated to losartan (n=42) (44.4±5.1% to 45.2±5.0%) and placebo (n=46) (43.2±6.3% to 43.6±6.9%). Losartan did not significantly improve RV EF in comparison with placebo (+0.51%; 95% confidence interval, -1.0 to +2.0; P=0.50). No significant treatment effects were found on secondary outcomes: left ventricular EF, peak aerobic exercise capacity, and N-terminal pro-brain natriuretic peptide (P>0.30 for all). In predefined subgroup analyses, losartan did not have a statistically significant impact on RV EF in subgroups with symptoms, restrictive RV, RV EF<40%, pulmonary valve replacement, or QRS fragmentation. However, in a post hoc analysis, losartan was associated with improved RV EF in a subgroup (n=30) with nonrestrictive RV and incomplete remodeling (QRS fragmentation and previous pulmonary valve replacement) (+2.7%; 95% confidence interval, +0.1 to +5.4; P=0.045). Losartan had no significant effect on RV dysfunction or secondary outcome parameters in repaired tetralogy of Fallot. Future larger studies may determine whether there might be a role for losartan in specific vulnerable subgroups. URL: https://www.clinicaltrials.gov. Unique identifier: NCT02010905.

The effects of increasing thoracic load carriage, using a backpack and body-armour ensemble, on peak aerobic power and exercise tolerance

The effects of increasing thoracic load carriage, using a backpack and body-armour ensemble, on peak aerobic power and exercise tolerance

Impaired myocardial relaxation with exercise determines peak aerobic exercise capacity in heart failure with preserved ejection fraction.

BackgroundHeart failure with preserved ejection fraction (HFpEF) is a clinical syndrome characterized by impaired exercise capacity due to shortness of breath and/or fatigue. Assessment of diastolic dysfunction at rest and with exercise may provide insight into the pathophysiology of exercise intolerance in HFpEF.AimsTo measure echocardio‐Doppler‐derived parameters of diastolic function as they relate to various indices of aerobic exercise capacity in HFpEF.MethodsWe selected 16 subjects with clinically stable HFpEF, no evidence of volume overload, but impaired functional capacity by cardiopulmonary exercise testing [peak oxygen consumption (VO2)]. We measured the transmitral E and A flow velocities, E/A ratio, and E deceleration time (DT) and tissue Doppler E′ velocity. We also indexed the E′ to the DT, as additional measure of impaired relaxation (E′DT), and calculated the diastolic functional reserve index (DFRI), as the product of E′ at rest and change in E′ with exercise.ResultsE′ velocity, at rest and peak exercise, as well as the DFRI positively correlated with peak VO2, whereas DT, E′DT, and E/E′ with exercise inversely correlated with peak VO2. Of note, the E′DT at rest also significantly predicted E′ velocity at peak exercise (R = +0.81, P < 0.001). Exercise E′ was the only independent predictor of peak VO2 at multivariable analysis (R = +0.67, P = 0.005).ConclusionsThe E′ velocity at peak exercise is a strong and independent predictor of aerobic exercise capacity as measured by peak VO2 in patients with HFpEF, providing the link between abnormal myocardial relaxation with exercise and impaired aerobic exercise capacity in HFpEF.

What Maintains the Metabolic Cost at Peak Aerobic Exercise in End Stage Renal Disease Patients?

Background: End-stage renal disease (ESRD) reduces performance of cardiopulmonary function and peak oxygen uptake (VO2 peak). The possible roles of oxygen delivery and oxygen extraction as limiting factors of exercise tolerance in ESRD patients were assessed.Methods: A cross-sectional study was conducted with twenty-two ESRD patients who underwent a peak cardiopulmonary and echocardiograph exercise test via leg cycle ergometry.Results: During exercise, elevated lactic acid occurred at a mean workload of 68.6 ± 5.7 Watts, corresponding to 78% of their respective peak work capacity. At peak exercise, in all measured variables except for systolic blood pressure, ESRD patients did not achieve normally predicted values. Heart rate, left ventricular end diastolic and systolic volumes, stroke volume, cardiac output, VO2 peak, arteriovenous oxygen difference, and workload were below normal values, while diastolic blood pressure, mean blood pressure and total peripheral resistance were above normal values.Conclusions: In ESRD patients, values for both oxygen delivery and extraction were far below the recorded values in normal. This suggests diminished central cardiopulmonary responses as well as reduced peripheral capacity to extract oxygen at the muscle level. Findings support the concept and possible importance of exercise rehabilitation programs in the approach for treatment of ESRD patients.

Coronary microvascular function, insulin sensitivity and body composition in predicting exercise capacity in overweight patients with coronary artery disease.

BackgroundCoronary artery disease (CAD) has a negative impact on exercise capacity. The aim of this study was to determine how coronary microvascular function, glucose metabolism and body composition contribute to exercise capacity in overweight patients with CAD and without diabetes.MethodsSixty-five non-diabetic, overweight patients with stable CAD, BMI 28–40 kg/m2 and left ventricular ejection fraction (LVEF) above 35 % were recruited. A 3-hour oral glucose tolerance test was used to evaluate glucose metabolism. Peak aerobic exercise capacity (VO2peak) was assessed by a cardiopulmonary exercise test. Body composition was determined by whole body dual-energy X-ray absorptiometry scan and magnetic resonance imaging. Coronary flow reserve (CFR) assessed by transthoracic Doppler echocardiography was used as a measure of microvascular function.ResultsMedian BMI was 31.3 and 72 % had impaired glucose tolerance or impaired fasting glucose. VO2peak adjusted for fat free mass was correlated with CFR (r = 0.41, p = 0.0007), LVEF (r = 0.33, p = 0.008) and left ventricular end-diastolic volume (EDV) (r = 0.32, p = 0.01) while it was only weakly linked to measures of glucose metabolism and body composition. CFR, EDV and LVEF remained independent predictors of VO2peak in multivariable regression analysis.ConclusionThe study established CFR, EDV and LVEF as independent predictors of VO2peak in overweight CAD patients with no or only mild functional symptoms and a LVEF > 35 %. Glucose metabolism and body composition had minor impact on VO2peak. The findings suggest that central hemodynamic factors are important in limiting exercise capacity in overweight non-diabetic CAD patients.

Heat acclimatization does not improve VO2max or cycling performance in a cool climate in trained cyclists.

This study investigated if well-trained cyclists improve V ˙ O 2 m a x and performance in cool conditions following heat acclimatization through natural outdoor training in hot conditions. Eighteen trained male cyclists were tested for physiological adaptations, V ˙ O 2 m a x , peak aerobic power output, exercise efficiency, and outdoor time trial (TT) performance (43.4 km in cool environment, ∼5-13 °C) before and after 2 weeks of training in a cool (CON, n = 9) or hot (∼35 °C, HA, n = 9) environment. After heat acclimatization, TT performance in the heat was improved by 16%; however, there was no change in the HA group in V ˙ O 2 m a x (4.79 ± 0.21 L/min vs 4.82 ± 0.35 L/min), peak aerobic power output (417 ± 16 W vs 422 ± 17 W), and outdoor TT performance in cool conditions (300 ± 14 W/69 ± 3 min vs 302 ± 9 W/69 ± 4 min). The present study shows that 2 weeks of heat acclimatization was associated with marked improvements in TT performance in the heat. However, for the well-trained endurance athletes, this did not transfer to an improved aerobic exercise capacity or outdoor TT performance in cool conditions.

Exercise training improves aerobic capacity, muscle strength, and quality of life in renal transplant recipients.

Renal transplant recipients (RTR) have reduced peak aerobic capacity, muscle strength, arterial function and an unfavorable cardiovascular disease risk (CVD) profile. This study compared the effects of 12 weeks of supervised endurance and strength training (EST, n = 16) versus usual care (UC, n = 15) on peak aerobic capicity, cardiovascular and skeletal muscle function, CVD risk profile, and quality of life (QOL) in RTR (55 ± 13 years). Peak aerobic capacity and exercise hemodynamics, arterial compliance, 24-h blood pressure, muscle strength, lean body mass, CVD risk score, and QOL were assessed before and after 12 weeks. The change in peak aerobic capacity (EST: 2.6 ± 3.1 vs. UC: -0.5 ± 2.5 mL/(kg·min)), cardiac output (EST: 1.7 ± 2.6 vs. UC: -0.01 ± 0.8 L/min), leg press (EST: 48.7 ± 34.1 vs. UC: -10.5 ± 37.7 kg) and leg extension strength (EST: 9.5 ± 10.3 vs. UC: 0.65 ± 5.5 kg) improved significantly after EST compared with UC. The overall change in QOL improved significantly after 12 weeks of EST compared with UC. No significant difference was found between groups for lean body mass, arterial compliance, 24-h blood pressure or CVD risk score. Supervised EST is an effective intervention to improve peak exercise aerobic capacity and cardiac output, muscle strength and QOL in clinically stable RTR.

Acute Exercise Effects on Measures of Attention and Impulsivity in Children with Attention Deficit/Hyperactivity Disorder

This study examined the effect of a single bout of exercise on measures of attention and impulsivity in children with attention deficit/hyperactivity disorder (ADHD). Children with ADHD (n = 21, 11.3 ± 1.8 yrs) and children without ADHD (n = 21, 11.6 ± 1.9 yrs) participated in the study. After performing an initial exercise test to measure peak aerobic exercise capacity, the children reported to the laboratory for 2 additional trials. For children with ADHD one trial was performed off medication and the other trial occurred on medication. During each testing session the Connor’s Continuous Performance Test II (CCPT II) was performed immediately before and after 20 minutes of intermittent exercise (30 sec exercise/30 sec rest) at 90% of peak aerobic work rate. Errors of omission, errors of commission, and reaction time (t-scores) were assessed from the CCPT II. The data were analyzed with a 3-way (group x trial x time) MANOVA. There was a significant increase in the error of omission t-score over time (pre to post exercise). There were no significant findings for the error of commission t-score. In the ADHD group the reaction time score was significantly higher than children without ADHD, significantly decreased with medication, and significantly increased over time. No other interaction or main effects were observed. Further research identifying the optimal exercise intensity and duration that can improve behavior, neurocognitive function, and academic performance is warranted.

Prior Eccentric Exercise Reduces V[Combining Dot Above]O2peak and Ventilatory Threshold but Does Not Alter Movement Economy During Cycling Exercise

Exercise-induced muscle damage (EIMD) has been shown to reduce force production and result in delayed-onset soreness and pain in the damaged muscle(s). Cycling in the presence of EIMD reduces peak power output and time-trial performance. However, its effect on peak aerobic capacity has not been widely studied. The purpose of this study was to examine the impact of EIMD targeted specifically to the quadriceps muscle group on peak oxygen consumption (V[Combining Dot Above]O2peak) during cycling. Ten participants (4 men, 6 women) completed a V[Combining Dot Above]O2peak test on a cycle ergometer before and 48 hours after performing 24 eccentric contractions with their right and left quadriceps with a weight equal to 120% of 1-repetition maximal concentric strength (1RM). The EIMD was assessed using 1RM, and muscle soreness was assessed using a 100-mm visual analog scale. The presence of EIMD was confirmed by a 9% reduction in 1RM (p = 0.0001) and increased ratings of soreness from 2.4 ± 2.1 to 24.6 ± 10.8 mm (p = 0.001). The V[Combining Dot Above]O2peak was reduced from 46.2 ± 9.7 to 41.8 ± 10.7 ml·kg·min (10%; p = 0.01) with participants terminating exercise at lower heart rates 191 ± 9 vs. 186 ± 10 b·min (p = 0.02) and power output 248 ± 79 vs. 238 ± 81 W (p = 0.02) after EIMD. Additionally, ventilatory threshold decreased from 34.2 ± 7.8 to 30.5 ± 8.5 ml·kg·min (11%; p = 0.031). Despite the reduction in V[Combining Dot Above]O2peak, cycling economy (p = 0.17) did not differ pre-EIMD and post-EIMD. These findings indicate that EIMD reduced peak aerobic exercise capacity to an extent that could result in meaningful reductions in exercise performance. The reduction is likely attributable to a combination of reduced strength, earlier accumulation of lactic acid, and heightened muscle pain during exercise.

Validity of predicting left ventricular end systolic pressure changes following an acute bout of exercise

ObjectivesLeft ventricular end systolic pressure (LV ESP) is important in assessing left ventricular performance and is usually derived from prediction equations. It is unknown whether these equations are accurate at rest or following exercise in a young, healthy population. DesignMeasured LV ESP vs. LV ESP values from the prediction equations were compared at rest, 15min and 30min following peak aerobic exercise in 60 participants. MethodsLV ESP was obtained by applanation tonometry at rest, 15min post and 30min post peak cycle exercise. ResultsMeasured LV ESP was significantly lower (p<0.05) at all time points in comparison to the two calculated values. Measured LV ESP decreased significantly from rest at both the post15 and post30 time points (p<0.05) and changed differently in comparison to the calculated values (significant interaction; p<0.05). The two LV ESP equations were also significantly different from each other (p<0.05) and changed differently over time (significant interaction; p<0.05). ConclusionsThe two commonly used prediction equations did not accurately predict either resting or post exercise LV ESP in a young, healthy population. Thus, LV ESP needs to be individually determined in young, healthy participants. Non-invasive measurement through applanation tonometry appears to allow for a more accurate determination of LV ESP.

Feasibility and Validity of a Graded One-Legged Cycle Exercise Test to Determine Peak Aerobic Capacity in Older People With a Lower-Limb Amputation

Information concerning exercise tolerance and aerobic capacity is imperative for generating effective and safe exercise programs. However, for older people with a lower-limb amputation, a standard exercise test is not available. The primary aim of the present study was to determine whether a graded 1-legged peak exercise test is feasible and provides a valid assessment of peak aerobic capacity in older people walking with a lower-limb prosthesis. This was a quasi-experimental case-control study. A total of 36 older people with a lower-limb prosthesis and 21 people who were able-bodied (controls) (overall mean age=61.7 years, SD=6.1) performed a discontinuous graded 1-legged exercise test. The peak respiratory exchange ratio was used as an indicator of maximal effort. The controls performed an additional 2-legged exercise test to provide insight into differences between the testing modes. All participants were able to perform the exercise test. Electrocardiographic tracings and blood pressure were adequately monitored. The controls and the people with a lower-limb amputation were able to stress the cardiovascular system to a similar extent. Analyses of construct validity revealed that the peak aerobic capacity measured with the 1-legged exercise test was able to distinguish between participants on the basis of age, body mass index, and sex to a similar extent as the conventional 2-legged exercise test. The results can be generalized only to people who are able to ambulate with their prosthesis. The graded 1-legged exercise test was feasible and provided a valid assessment of peak aerobic capacity and exercise tolerance in older people walking with a lower-limb prosthesis.

Factors defining oxygen uptake at peak exercise in aged people

Maximum oxygen uptake (VO2max) is defined as the highest rates at which oxygen can be taken up and utilized by the body during severe exercise indicating the cardiopulmonary fitness of the individual. It is one of the main variables in the field of exercise physiology and is frequently used to indicate the cardio-respiratory fitness of an individual [1]. Consequently, there has been great interest in identifying the physiological factors that limit VO2max and determining the role of this variable in endurance and anaerobic performances. Today, it is universally accepted that there is a physiological upper limit to the body's ability to consume oxygen. In the scientific literature, an increase in VO2max is the most common method of demonstrating a training effect. In addition, VO2max is frequently used in the development of an exercise prescription in health and disease. Given these applications of VO2max, there has been great interest in identifying the physiological factors that limit VO2max and determining the role of this variable in endurance performance. Aging-related changes occur mainly in the cardiopulmonary and skeletal muscles, bringing about a reduction in physical performance [7]. Such myocardial and peripheral functional changes include a decline in the maximum heart rate, stroke volume, and contractility, and an increase in peripheral vascular resistance. Consequently, the maximal VO2max decreases. The primary aging process, itself genetically associated, occurs both independently of lifestyle and in the absence of disease [4]. Accordingly, one may expect maximal cardiac output to decrease with aging irrespective of lifestyle because of genetic factors. Reduced arteriovenous oxygen difference at maximal effort [6] is the second factor associated with decrease with aging of VO2max. Incremental exercise is characterized by exposing the subjects to a high degree of load which may alter the left ventricular contractility and function [5]. This has the effect of placing a large load on the left ventricular which might have significant effects on oxygen delivery to the working muscles. Thus, oxygen delivery to the working muscle may be reduced, and since metabolic demand during incremental exercise is increased over time to maximum, elderly subjects may maintain the energy supply due to the balance between O2 delivery and extraction. Untrained and trained elderly can increase the response of the central factors i.e., cardiopulmonary without a significant reduction in peripheral ability to extract oxygen at the muscle level. It was found that in elderly subjects, skeletal muscle mitochondrial capacity, tissue blood flow capacity, and oxygen exchange capacity appear to be wellmatched. It seems that intrinsic mitochondrial function and regulation are not altered significantly. Values for cardiac output at peak aerobic exercise are low in the untrained compared to the trained at maximal aerobic exercise. The lower cardiac output in the untrained elderly at peak exercise is related to the limited heart rate reserve, stroke volume, contractility, and to the inappropriate adjustment of the circulation [3, 5]. The augmentation in maximal oxygen uptake in the trained elderly in response to M. Sagiv (*) :D. Ben-Sira : R. Amir Sports Medicine and Rehabilitation Division, Zinman College of Physical Education and Sport Sciences Wingate, Netany, Israel 42902 e-mail: sagiv-moran@wincol.ac.il

What Maintains Energy Supply at Peak Aerobic Exercise in Trained and Untrained Older Men?

Background: Aging-related changes occur mainly in the cardiopulmonary system and skeletal muscles, bringing about a reduction in physical performance. Consequently, maximal oxygen uptake (VO₂max) decreases. Objectives: The current study investigated exercise oxygen utilization during maximal aerobic exercise in trained and untrained elderly. Methods: Fifteen trained (59.3 ± 1.1 years) and 15 untrained (60.1 ± 1.1 years) elderly underwent a peak cardiopulmonary exercise test on a bicycle ergometer. Arterial O₂was defined from echocardiograph and venous oxygen content. Results: At rest, trained compared to untrained elderly had significantly (p < 0.05) higher values of end diastolic volume (108.1 ± 5.8 and 100.7 ± 6.2 ml, respectively) and stroke volume (68.1 ± 4.3 and 57.3 ± 6.5 ml, respectively), while heart rate (68.7 ± 9.3 and 81.3 ± 8.2 beats · min^–1, respectively), and mean arterial blood pressure (90.6 ± 6.9 and 95.4 ± 7.2 mm Hg, respectively) were significantly lower. At peak aerobic test, the trained elderly, compared to the untrained subjects, achieved significantly (p < 0.05) higher values of end diastolic volume (156.1 ± 8.2 and 134.1 ± 7.6 ml, respectively), stroke volume (123.0 ± 7.9 and 96.0 ± 4.8 ml, respectively), cardiac output (20.2 ± 1.5 and 15.0 ± 1.3 liters·min^–1, respectively) and oxygen uptake (42.1 ± 2.1 and 31.1 ± 2.4 ml·kg^–1·min^–1, respectively), while diastolic blood pressure (70.3 ± 5.6 and 77.5 ± 4.2 mm Hg, respectively) and total peripheral resistance [4.3 ± 0.8 and 5.9 ± 1.41 (dyn·s^–1·cm^–5)·10^–1, respectively], were significantly (p < 0.05) lower. Conclusions: The present study suggests that the differences between trained and untrained elderly in absolute oxygen uptake of the working muscles and peak power output at maximal exercise test are due to physical activity status. The higher aerobic capacity in the trained elderly is related to increased cardiovascular function and to a lesser extent to increased muscle mitochondria concentration and capillarity. Although untrained elderly have reduced maximal oxygen uptake at peak aerobic exercise, intrinsic regulation of mitochondrial function does not seem to be significantly altered because of aging associated physical inactivity. Therefore, untrained elderly can partially compensate for their lower cardiac output by increasing oxygen extraction to levels comparable with those of trained elderly.