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Stephen F. Figoni, Richard A. Boileau, Benjamin H. Massey and Joseph R. Larsen

The purpose of this study was to compare quadriplegic and able-bodied men on selected cardiovascular and metabolic responses to arm-crank ergometry at the same rate of oxygen consumption (V̇O2). Subjects included 11 untrained, spinal cord-injured, C5–C7 complete quadriplegic men and 11 untrained, able-bodied men of similar age (27 years), height (177 cm), and mass (65 kg). Measurement techniques included open-circuit spirometry, impedance cardiography, and electrocardiography. Compared with the able-bodied group, at the V̇O2 of 0.5 L/min, the quadriplegics displayed a significantly higher mean heart rate and arteriovenous O2 difference, lower stroke volume and cardiac output, and similar myocardial contractility. These results suggest that quadriplegic men achieve an exercise-induced V̇O2 of 0.5 L/min through different central cardiovascular adjustments than do able-bodied men. Quadriplegics deliver less O2 from the heart toward the tissues but extract more O2 from the blood. Tachycardia may contribute to low cardiac preload and low stroke volume, while paradoxically tending to compensate for low stroke volume by minimizing reduction of cardiac output.

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Stamatis Agiovlasitis, Kenneth H. Pitetti, Myriam Guerra and Bo Fernhall

This study examined whether 20-m shuttle-run performance, sex, body mass index (BMI), age, height, and weight are associated with peak oxygen uptake (VO2peak) in youth with Down syndrome (DS; n = 53; 25 women, age 8–20 years) and whether these variables can be used to develop an equation to predict VO2peak. BMI, 20-m shuttle-run performance, and sex were significantly associated with VO2peak in youth with DS, whereas age, height, and weight were not. A regression model included only shuttle-run performance as a significant predictor of VO2peak; however, the developed prediction equation had low individual predictability. Therefore, 20-m shuttle-run performance alone does not provide valid prediction of VO2peak in youth with DS. Sex, BMI, age, height, and weight do not improve the prediction of VO2peak.

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Paul M. Vanderburgh

Previously there existed no efficacious maximal effort, VO2peak prediction test for subjects who, because of injury, can exercise at high intensity only on a device such as a cycle ergometer. This study's purpose was to develop and validate such a test, a 12-Minute Stationary Cycle Ergometer Test (12MSCET), for college-age physically active men and women. For 60 college-age men and women, and a gender-based resistance setting, the total work done on the 12MSCET and body weight were found to be highly predictive of VO2peak, measured via open circuit spirometry. Furthermore, the torques required for such a test are, for this sample, approximately 50% of those required in other predictive protocols. To date, the 12MSCET has been used for VO2peak assessment of over 300 military cadets who, because of injury, found cycling their only efficacious high-intensity aerobic modality.

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Mário A.M. Simim, Marco Túlio de Mello, Bruno V.C. Silva, Dayane F. Rodrigues, João Paulo P. Rosa, Bruno Pena Couto and Andressa da Silva

3 ± 2 hr/week Two visits to laboratory (first = incremental test and VO 2 peak test; second = 20-min exercise tests—50% and 70% of VO 2peak ) TRA VO 2 %VO 2peak HR %HR peak [Lac] RPE HR monitors Lactate Pro handbike Borg scale 6–20 PPO Handbike Barfield et al. ( 2010 ) 9 WR SCI (C6–C7) 12 ± 7 9 ± 6

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Andreas Schuchert and Thomas Meinertz

Context:

It is more feasible to assess functional capacity with an exercise test than to measure peak-exercise VO2.

Objective:

To assess whether maximal workload reliably predicts peak VO2.

Patients:

Thirty-six patients after aortic-valve replacement during routine follow-up.

Design:

Incremental symptom-limited cycle exercise test in the upright position with increments of 20 W/min.

Setting:

Out-clinic patients, university hospital.

Main Outcome Measures:

Maximal workload, ventilatory threshold, and peak VO2.

Results:

Maximal workload was 151 ± 39 W, and peak VO2, 1649 ± 486 ml/min. The correlation coefficient between maximal workload and peak VO2 was r = .92 (P < .0001). The regression equation for the estimation of peak VO2 was y = 11.7 (maximal workload in watts) – 110.7. Peak VO2 calculated with this equation was 1657 ± 451 ml/min.

Conclusions:

Maximal workload during ergometry in the upright position reliably predicted peak VO2.

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Martin Švehlík, Kryštof Slabý, Tomáš Trc̆ and Jir̆í Radvanský

The aim of the study is to investigate whether the net nondimensional oxygen utilization scheme is able to detect postoperative improvement in the energy cost of walking in children with cerebral palsy and to compare it with a body mass normalization scheme. We evaluated 10 children with spastic cerebral palsy before and 9 months after equinus deformity surgery. Participants walked at a given speed of 2 km/hr and 3 km/hr on a treadmill. Oxygen utilization was measured, and mass relative VO2 and net nondimensional VO2 were calculated. Coefficient of variation was used for the description of variability among subjects. Postoperatively, gait kinematics normalized and the mass relative VO2 and net nondimensional VO2 showed significant improvement. Net nondimensional VO2 is able to detect postoperative improvement with smaller variability among subjects than body mass related normalization in children with cerebral palsy.

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John A. Mercer, Janet S. Dufek and Barry T. Bates

Objective:

To compare peak oxygen consumption (VO2) and heart rate (HR) during treadmill (TM) running and exercise on an elliptical trainer (ET).

Design:

A graded exercise test (GXT) during TM running and ET exercise.

Participants:

Physically active college students (N = 14; 25 ± 4.6 years). Each completed a TM GXT and ET GXT on separate days.

Results:

There were no differences in either VO2peak or peak HR between TM (53.0 ± 7.7 ml · kg–1 · min–1, 193.4 ± 9.4 bpm) and ET (51.6 ± 10.7 ml · kg–1 · min–1, 191.2 ± 11.5 bpm; P > .05). Correlations between HR and VO2 data for all stages of exercise for all subjects were similar between machines (ET: r = .88; TM: r = .95; P > .05).

Conclusion:

No adjustments to the target HR used during TM running are necessary when using the ET.

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Jerry Mayo, Brian Lyons, Kendal Honea, John Alvarez and Richard Byrum

Context:

Rehabilitation specialists should understand cardiovascular responses to different movement patterns.

Objective:

To investigate physiological responses to forward- (FM), backward- (BM), and lateral-motion (LM) exercise at self-selected intensities.

Design:

Within-subjects design to test independent variable, movement pattern; repeated-measures ANOVA to analyze oxygen consumption (VO2), heart rate (HR), respiratory-exchange ratio (RER), and ratings of perceived exertion (RPE).

Participants:

10 healthy women.

Results:

VO2 and HR were significantly higher during LM than during FM and BM exercise. The respective VO2 (ml · kg · min–1) and HR (beats/min) values for each condition were FM 25.19 ± 3.6, 142 ± 11; BM 24.24 ± 2.7, 145 ± 12; and LM 30.5 ± 4.6, 160 ± 13. No differences were observed for RER or RPE.

Conclusions:

At self-selected intensities all 3 modes met criteria for maintaining cardiovascular fitness. Practitioners can use these results to develop rehabilitation programs based on clients’ perception and level of discomfort

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Stamatis Agiovlasitis, Jeffrey A. McCubbin, Joonkoo Yun, Michael J. Pavol and Jeffrey J. Widrick

This study examined whether the net rate of oxygen uptake (VO2net) and the net oxygen uptake per kilometer (VO2net/km) are affected during walking in adults with Down syndrome (DS) and whether their preferred walking speed (PWS) minimizes the VO2net/km. Respiratory gases were collected as 14 adults with DS and 15 adults without DS completed a series of treadmill walking trials. PWS was measured over 15 meters in a hallway. The VO2net and the VO2net/km were higher in adults with DS than adults without DS. The overground PWS normalized for leg length was the same for both groups and did not appear to minimize the VO2net/km. Thus, adults with DS are less economical during walking than adults without DS. The overground PWS does not minimize the metabolic cost during treadmill walking.

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Eadric Bressel, Gerald Smith, Andrew Miller and Dennis Dolny

Context: Quantification of the magnitudes of fluid resistance provided by water jets (currents) and their effect on energy expenditure during aquatic-treadmill walking is lacking in the scientific literature. Objective: To quantify the effect of water-jet intensity on jet velocity, drag force, and oxygen uptake (VO2) during aquatic-treadmill walking. Design: Descriptive and repeated measures. Setting: Athletic training facility. Participants, Interventions, and Measures: Water-jet velocities were measured using an electromagnetic flow meter at 9 different jet intensities (0-80% maximum). Drag forces on 3 healthy subjects with a range of frontal areas (600, 880, and 1250 cm2) were measured at each jet intensity with a force transducer and line attached to the subject, who was suspended in water. Five healthy participants (age 37.2 ± 11.3 y, weight 611 ± 96 N) subsequently walked (~1.03 m/s or 2.3 miles/h) on an aquatic treadmill at the 9 different jet intensities while expired gases were collected to estimate VO2. Results: For the range of jet intensities, water-jet velocities and drag forces were 0-1.2 m/s and 0-47 N, respectively. VO2 increased nonlinearly, with values ranging from 11.4 ± 1.0 to 22.2 ± 3.8 mL × kg-1 × min-1 for 0-80% of jet maximum, respectively. Conclusions: This study presented methodology for quantifying water-jet flow velocities and drag forces in an aquatic-treadmill environment and examined how different jet intensities influenced VO2 during walking. Quantification of these variables provides a fundamental understanding of aquatic-jet use and its effect on VO2. In practice, these results indicate that VO2 may be substantially increased on an aquatic treadmill while maintaining a relatively slow walking speed.