Accurate prediction of cardiorespiratory fitness using cycle ergometry in minimally disabled persons with relapsing-remitting multiple sclerosis

Motl RW, Fernhall B. Accurate prediction of cardiorespiratory fitness using cycle ergometry in minimally disabled persons with relapsing-remitting multiple sclerosis.ObjectiveTo examine the accuracy of predicting peak oxygen consumption (Vo_2peak) primarily from peak work rate (WR_peak) recorded during a maximal, incremental exercise test on a cycle ergometer among persons with relapsing-remitting multiple sclerosis (RRMS) who had minimal disability.DesignCross-sectional study.SettingClinical research laboratory.ParticipantsWomen with RRMS (n=32) and sex-, age-, height-, and weight-matched healthy controls (n=16) completed an incremental exercise test on a cycle ergometer to volitional termination.InterventionNot applicable.Main Outcome MeasuresMeasured and predicted Vo_2peak and WR_peak.ResultsThere were strong, statistically significant associations between measured and predicted Vo_2peak in the overall sample (R²=.89, standard error of the estimate=127.4mL/min) and subsamples with (R²=.89, standard error of the estimate=131.3mL/min) and without (R²=.85, standard error of the estimate=126.8mL/min) multiple sclerosis (MS) based on the linear regression analyses. Based on the 95% confidence limits for worst-case errors, the equation predicted Vo_2peak within 10% of its true value in 95 of every 100 subjects with MS.ConclusionsPeak Vo₂ can be accurately predicted in persons with RRMS who have minimal disability as it is in controls by using established equations and WR_peak recorded from a maximal, incremental exercise test on a cycle ergometer.     

Assessment of V̇o2peak and Exercise Capacity After Stroke: A Validity Study of the Human Activity Profile Questionnaire

ObjectiveTo investigate the concurrent validity of the Human Activity Profile (HAP) in individuals after stroke to provide the peak oxygen uptake (V?o_2peak) and the construct validity of the HAP to assess exercise capacity, and to provide equations based on the HAP outcomes to estimate the distance covered in the Incremental Shuttle Walking Test (ISWT).DesignCross-sectional study.SettingUniversity laboratory.ParticipantsIndividuals (N=57) aged 54±11 years who have experienced stroke.InterventionNot applicable.Main Outcome MeasuresAgreement between the V?o_2peak provided by the HAP (lifestyle energy consumption [LEC] outcome, in mL/kg^?1/min^?1) and the criterion standard measure of the V?o_2peak (mL/kg^?1/min^?1), obtained through the symptom-limited Cardiopulmonary Exercise Test (CPET). Correlation between the HAP outcomes (LEC, maximum activity score [MAS], and adjusted activity score [AAS]) and the construct measure: the distance covered (in meters) in the ISWT. An equation to estimate the distance covered in the ISWT was determined.ResultsHigh magnitude agreement was found between the V?o_2peak, in mL/kg^?1/min^?1, obtained by the symptom-limited CPET and the value of V?o_2peak, in mL/kg^?1/min^?1, provided by the HAP (LEC) (intraclass correlation coefficient, 0.75; P<.001). Low to moderate magnitude correlations were found between the distance covered in the ISWT and the HAP (LEC/MAS/AAS) (0.34≤ρ≤0.58). The equation to estimate the distance covered in the ISWT explained 31% of the variability of the ISWT (ISWT_estimated, –361.91+(9.646xAAS)).ConclusionThe HAP questionnaire is a clinically applicable way to provide a valid value of V?o_2peak (in mL/kg^?1/min^?1) and to assess the exercise capacity of individuals after stroke. Furthermore, an equation to estimate the distance covered in the submaximal field exercise test (ISWT) based on the result of the AAS (in points) was provided.     

Prediction of peak oxygen consumption from the ratings of perceived exertion during a graded exercise test and ramp exercise test in able-bodied participants and paraplegic persons

Al-Rahamneh HQ, Eston RG. Prediction of peak oxygen consumption from the ratings of perceived exertion during a graded exercise test and ramp exercise test in able-bodied participants and paraplegic persons.

Objective

To assess the accuracy of predicting peak oxygen consumption (Vo₂peak) from a graded exercise test (GXT) and a ramp exercise test during arm exercise in able-bodied persons and persons with paraplegia using ratings of perceived exertion (RPEs).

Design

Each participant performed a GXT (started at 30W and increased by 15W every 2min) and a ramp exercise test (started at 0W and increased by 15W·min⁻¹).

Setting

Universities' laboratories.

Participants

Able-bodied men (n=13; mean ± SD, 27.2±4.3y) and men with paraplegia (n=12; 31.1±5.7y). Six of the persons with paraplegia had flaccid paralysis as a result of poliomyelitis infection. The other 6 persons had complete spinal cord injuries with neurologic levels at and below T6.

Intervention

Not applicable.

Main Outcome Measures

Prediction of Vo₂peak by extrapolating submaximal oxygen consumption (V?o₂) and RPE values to RPE 20 on the Borg 6 to 20 RPE scale.

Results

This study showed a very strong linear relationship between RPE and V?o₂ during the GXT and the ramp test for able-bodied persons (R²≥.95 and R²≥.96, respectively) and persons with paraplegia (R²≥.96 and R²≥.95, respectively). There was no significant difference between measured and predicted Vo₂peak from RPEs before and including RPE 13, 15, and 17 during the GXT for persons with paraplegia (P>.05). For the able-bodied participants, there was no significant difference between measured and predicted Vo₂peak from RPEs before and including RPE 15 and 17 during the ramp exercise test (P>.05).

Conclusion

The GXT provided acceptable predictions of Vo₂peak for persons with paraplegia, and the ramp test provided acceptable predictions of Vo₂peak for able-bodied persons.     

Ventilatory response and arterial potassium concentration during incremental exercise in patients with chronic airways obstruction

Summary. The relationship of ventilation response (V?_E) to arterial potassium concentration (K⁺) during ramp incremental exercise was assessed in nine patients with chronic obstructive pulmonary disease (COPD), and in 10 healthy subjects. For COPD patients the maximum oxygen uptake (VO_max) was 19.6±3.8 ml kg^-1 min^-1 (± SD), and percentage of forced expired volume at 1 s (% FEV₁) was 47.8 ± 10.4%. In healthy subjects, Vo₂max was 44.4±7.0 ml kg^-1 min^-1 and FEV₁, was 89.7 ± 7.4%. Breath-by-breath determinations for V?_E, oxygen uptake (V?o₂) and carbon dioxide output (V?co₂), as well as determinations for K⁺, partial pressure of oxygen (Po₂), partial pressure of carbon dioxide (Pco₂), pH and lactate in arterial blood were performed during a workout on an exercise bicycle at a ramp function work rate of 20 W min^-1, preceded by a 40 min warm-up period. The major findings in the present study are: (1) that there is a linear relation between ventilation and arterial K⁺ concentration during ramp exercise in both healthy subjects and COPD patients; (2) that the slope of the V?_E-K⁺ relationship is significantly lower in COPD patients (16.2 ± 7.31 min^-1 mM^-1) than in normal subjects (37.4 ± 6.91 min^-1 mM^-1, P<0.01); and, (3) that the slope of the V?_E-K⁺ relationship is significantly related to the ability to ventilate during maximal exercise in both healthy subjects and COPD patients (P<0.05). It is thought that the significantly reduced slope of the V?_E-K⁺ relationship in the COPD patients could be interpreted as a reduced sensitivity to the stimulus and/or as a mechanical impairment of the ventilation.     

Day‐to‐day variation in oxygen consumption at submaximal loads during ergometer cycling by adolescents

The day‐to‐day variation in oxygen consumption (V˙O₂) during ergometer cycling by 20 healthy adolescents, 10 females and 10 males, was measured using indirect calorimetry. The two sets of measurements were performed on two consecutive days. Great care was taken to minimize possible disturbing factors. Cycling started at 50 and 100 W for female and male adolescents, respectively. The load was increased at a rate of 5 W 30 s^?1. In order to reach steady state, the load was kept constant for 3·5 min twice during the cycling session, at 100 and 130 W for the females and at 130 and 160 W for the males. Cycling continued until exhaustion. The maximal loads were 196 W (mean) and 271 W (mean) for females and males, respectively. At the maximal loads the day‐to‐day variation (±2 SD) in oxygen consumption (V˙O₂) was ±330 ml min^?1 for females and 390 ml min^?1 for males. At the submaximal loads the day‐to‐day variation in heart rate (HR) was 9·3 beats min^?1 (±2 SD) (coefficient of variation, CV=3·4% at 130 W) for both sexes. The day‐to‐day variation in oxygen consumption (V˙O₂) was ±199 ml min^?1 (±2 SD) at the different submaximal loads and did not differ between female and male adolescents (CV=5·7% at 130 W). This natural day‐to‐day variation must be taken into consideration when using a submaximal ergometer cycling test for the evaluation of physical capacity in the two sexes.     

Can the Six-Minute Walk Test Predict Peak Oxygen Uptake in Men With Heart Transplant?

Doutreleau S, Di Marco P, Talha S, Charloux A, Piquard F, Geny B. Can the six-minute walk test predict peak oxygen uptake in men with heart transplant?

Objective

To determine whether the six-minute walk test (6MWT) might predict peak oxygen consumption (Vo₂peak) after heart transplantation.

Design

Case-control prospective study.

Setting

Public hospital.

Participants

Patients with heart transplant (n=22) and age-matched sedentary male subjects (n=13).

Interventions

Not applicable.

Main Outcome Measures

Exercise performance using a maximal exercise test, distance walked using the 6MWT, heart rate, and Vo₂peak.

Results

Compared with controls, exercise performance was decreased in patients with heart transplant with less distance ambulated (516±13m vs 592±13m; P<.001) and a decrease in mean Vo₂peak (23.3±1.3 vs 29.6±1mL·min⁻¹·kg⁻¹; P<.001). Patients with heart transplant showed an increased resting heart rate, a response delayed both at the onset of exercise and during recovery. However, the patient's heart rate at the end of the 6MWT was similar to that obtained at the ventilatory threshold. The formula did not predict measured V?o₂, with a weak correlation observed between the six-minute walk distance and both Vo₂peak (r=.53; P<.01) and ventilatory threshold (r=.53; P<.01) after heart transplantation. Interestingly, when body weight was considered, correlations coefficient increased to .74 and .77, respectively (P<.001).

Conclusions

In heart transplant recipients, the 6MWT is a safe, practical, and submaximal functional test. The distance-weight product can be used as an alternative method for assessing the functional capacity after heart transplantation but cannot totally replace maximal V?o₂ determination.     

Reference Fitness Values in the Untrained Spinal Cord Injury Population

ObjectiveEstablish reference values of cardiorespiratory fitness applicable to the general, untrained spinal cord injury (SCI) population.DesignData were retroactively obtained from 12 studies (May 2004 to May 2012).SettingAn institution-affiliated applied physiology research laboratory.ParticipantsA total of 153 men and 26 women (age, 18–55y) with chronic SCI (N=179) were included. Participants were not involved in training activities for 1 or more months before testing and were able to complete a progressive resistance exercise test to determine peak oxygen consumption (Vo₂peak).InterventionsNot applicable.Main Outcome MeasurePercentile ranking (poor<20%; fair; 20%–40%; average, 40%–60%; good, 60%–80%; excellent, 80%–100%) used to establish reference values.ResultsReference cardiorespiratory fitness values based on functional classification as paraplegic or tetraplegic were established (paraplegic: median, 16.0mL·kg⁻¹·min⁻¹; range, 1.4–35.2mL·kg⁻¹·min⁻¹; tetraplegic: median, 8.8mL·kg⁻¹·min⁻¹; range, 1.5–21.5mL·kg⁻¹·min⁻¹) for untrained men and women. For the primary outcome measure (Vo₂peak), persons with paraplegia had significantly higher values than did persons with tetraplegia (P<.001). Although men had higher values than did women, these differences did not reach significance (P=.256). Regression analysis revealed that motor level of injury was associated with 22.3% of the variability in Vo₂peak (P<.001), and an additional 8.7% was associated with body mass index (P<.001). No other measure accounted for additional significant variability.ConclusionsEstablished reference fitness values will allow investigators/clinicians to stratify the relative fitness of subjects/patients from the general SCI population. Key determinants are motor level of injury and body habitus, yet most variability in aerobic capacity is not associated with standard measures of SCI status or demographic characteristics.     

Maximal Cardiorespiratory Fitness Testing in Individuals With Chronic Stroke With Cognitive Impairment: Practice Test Effects and Test-Retest Reliability

Objectives

To evaluate, for individuals with chronic stroke with cognitive impairment, (1) the effects of a practice test on peak cardiorespiratory fitness test results; (2) cardiorespiratory fitness test-retest reliability; and (3) the relationship between individual practice test effects and cognitive impairment.

Design

Cross-sectional.

Setting

Rehabilitation center.

Participants

A convenience sample of 21 persons (men [n=12] and women [n=9]; age range, 48–81y; 44.9±36.2mo poststroke) with cognitive impairments who had sufficient lower limb function to perform the test.

Interventions

Not applicable.

Main Outcome Measure

Peak oxygen consumption (Vo₂peak, ml·kg⁻¹·min⁻¹).

Results

Test-retest reliability of Vo₂peak was excellent (intraclass correlation coefficient model 2,1 [ICC_2,1]=.94; 95% confidence interval [CI], .86–.98). A paired t test showed that there was no significant difference for the group for Vo₂peak obtained from 2 symptom-limited cardiorespiratory fitness tests performed 1 week apart on a semirecumbent cycle ergometer (test 2–test 1 difference, −.32ml·kg⁻¹·min⁻¹; 95% CI, −.69 to 1.33ml·kg⁻¹·min⁻¹; P=.512). Individual test-retest differences in Vo₂peak were, however, positively related to general cognitive function as measured by the Mini-Mental State Examination (ρ=.485; P<.026).

Conclusions

Vo₂peak can be reliably measured in this group without a practice test. General cognitive function, however, may influence the effect of a practice test in that those with lower general cognitive function appear to respond differently to a practice test than those with higher cognitive function.     

Predicting Exercise Capacity Through Submaximal Fitness Tests in Persons With Multiple Sclerosis

Kuspinar A, Andersen RE, Teng SY, Asano M, Mayo NE. Predicting exercise capacity through submaximal fitness tests in persons with multiple sclerosis.

Objective

To estimate, for persons with multiple sclerosis (MS), the extent to which peak oxygen consumption (Vo₂peak) can be predicted by the results on submaximal tests.

Design

Cross-sectional study.

Setting

Three MS clinics in the Greater Montreal region, Canada.

Participants

A center-stratified random sample of 135 women and 48 men was drawn (N=183). A subgroup of 59 subjects with MS, who were able to perform the step test, was selected from this sample to complete the maximal exercise test.

Interventions

Not applicable.

Main Outcome Measure

Vo₂peak.

Results

In this sample (mean age ± SD, 39 ± 9y; median Expanded Disability Status Scale=1.5), the mean Vo₂peak ± SD was 27.6 ± 7.3mL·kg⁻¹·min⁻¹. This value is considerably low when compared with healthy persons, ranking below the 25th percentile for both men and women. In a multivariate regression analysis, the step test and grip strength were identified as the only significant predictors of Vo₂peak. When combined with body weight, grip strength and the step test explained 74% of the variance in Vo₂peak.

Conclusions

Patients with MS with a mild degree of disability exhibit marked reductions in exercise capacity. Also, in persons with MS, submaximal tests are good predictors of exercise capacity. These measures may be used in clinical settings to help assess and monitor maximum oxygen consumption and in research to evaluate the effect of exercise-related interventions. Furthermore, they will allow people with MS to self-monitor their exercise capacity and be more actively engaged in taking charge of their fitness level.     

Is the Fear Avoidance Model Associated With the Reduced Level of Aerobic Fitness in Patients With Chronic Low Back Pain?

Smeets RJ, van Geel KD, Verbunt JA. Is the fear avoidance model associated with the reduced level of aerobic fitness in patients with chronic low back pain?

Objectives

To compare aerobic fitness of patients with chronic low back pain (CLBP) against healthy controls and to assess whether variables of the fear avoidance model are associated with loss of aerobic fitness.

Design

A case-comparison study.

Setting

Rehabilitation centers.

Participants

Patients with CLBP (n=223), and normative data from healthy subjects (n=18,082).

Interventions

Not applicable.

Main Outcome Measures

Maximal oxygen uptake (V?o₂max) was estimated on the basis of a modified submaximal Åstrand bicycle test performed by patients with CLBP (observed level of aerobic fitness) and compared with the normative data of healthy controls matched for age, sex, and level of sport activity (expected level of aerobic fitness). Pain (visual analog scale); disability (Roland Disability Questionnaire); pain-related fear (Tampa Scale for Kinesiophobia); depression (Beck Depression Inventory); catastrophizing (Pain Catastrophizing Scale); and the level of activity during sport, work/household, and leisure time (Baecke Physical Activity Questionnaire) were assessed. Multiple linear regression analysis was performed with the difference of the observed and expected level of aerobic fitness as dependent variable and putative influential factors including those of the fear avoidance model as independent variables.

Results

V?o₂max could be calculated in 175 (78%) of the patients. Both men and women with CLBP had significant lower V?o₂max than expected (10.3mL/kg lean body mass (LBM)×min⁻¹ and 6.5mL/kg LBM×min⁻¹, respectively; P<.001). The levels of activity during leisure time and work/household were significantly associated with this reduced level of aerobic fitness. However, the variables of the fear avoidance model were not.

Conclusions

Most patients with CLBP-associated disability have a lower level of aerobic fitness, but this is not associated with fear avoidance.     

An Equation With Clinical Applicability and Adequate Validity to Predict the Maximum Oxygen Consumption of Individuals Post-stroke

ObjectiveTo develop an equation with clinical applicability and adequate validity to predict the maximum oxygen consumption (V̇o_2max) of individuals post-stroke.DesignA cross-sectional study.SettingA university laboratory.ParticipantsIndividuals post-stroke in the chronic phase (at least 6 months post-stroke). Step-1 (equation development): n=50, aged 55±12 years; Step-2 (validity investigation): n=20, aged 58±8 years (N=50 [step 1], N=20 [step 2]).InterventionsNot applicable.Main Outcome Measure(s)Step-1 (equation development): multiple linear regression analysis was performed. Dependent variable: V̇o_2max (mL/kg^/min) in the cardiopulmonary exercise test. Independent variables: age (years), sex (1-women, 2-men), body mass index (BMI) (kg/m²), and distance (meters) in the Six-Minute Walk Test (6MWT) (6MWT-Equation) or in the Incremental Shuttle Walk Test (ISWT) (ISWT-Equation). Step-2 (validity investigation): agreement between the V̇o_2max measured and predicted was evaluated with the intraclass correlation coefficient (ICC) with 95% confidence interval (CI) and the Bland-Altman method (α=5%).ResultsIn step-1 (equation development), the 4 independent variables for each equation were retained (6MWT-Equation: R²=0.68, P<.001; ISWT-Equation: R²=0.58, P<.001). In step-2 (validity investigation), the 6MWT-Equation showed an ICC of 0.73 (95% CI=0.30, 0.89; P=.004) and a mean bias of 0.003 mL/kg/min; and the ISWT-Equation showed an imprecise ICC of 0.55 (95% CI=-0.12, 0.82; P=.045) and a mean bias of 0.971 mL/kg/min. 6MWT-Equation (V̇o_2max=22.239+0.02 × distance in the 6MWT+4.039 × sex-0.157 × age-0.265 × BMI) showed adequate validity.ConclusionsAn equation with clinical applicability and adequate validity in the investigated sample was developed to predict the V̇o_2max of individuals post-stroke in the chronic phase (6MWT-Equation). Future studies with larger sample should investigate its external validity.     

Effect of exercise training and detraining on gas exchange kinetics in patients with chronic obstructive pulmonary disease

Symptom-limited incremental exercise tests are used to estimate the training effect on patients with chronic obstructive pulmonary disease (COPD). However, there is a need for objective parameters for measurement on submaximal exercise testing. The purpose of this study was to assess the usefulness of measurement of oxygen uptake (V?O₂) kinetics during a constant work rate exercise test of patients with COPD after exercise training. Eleven patients with COPD performed exercise tests before and after cycle ergometer training on 3 days per week for 8 weeks; they then went without training for 5 months and performed the same tests. They performed an incremental exercise test to symptom-limited maximum and a constant work rate exercise test for 6 min on a cycle ergometer. The time constant of V?O₂ during the onset of constant work rate exercise was significantly decreased (from 63·5±7·8 s to 53·2±8·0 s) after exercise training (P=0·021), but was significantly increased (to 73·4±14·9 s) after 5 months without training (P=0·001). The oxygen pulse at steady state during constant work rate exercise testing was significantly increased after exercise training but decreased 5 months later. The change in blood lactate from rest to steady state during constant work rate exercise was significantly decreased after exercise training, but increased 5 months later. Measurement of the time constant of V?O₂ and oxygen pulse during constant work rate exercise are useful for the objective evaluation of the training effect of patients with COPD.     

Relationship Between Perceived Exertion and Physiologic Markers During Arm Exercise With Able-Bodied Participants and Participants With Poliomyelitis

Al-Rahamneh HQ, Faulkner JA, Byrne C, Eston RG. Relationship between perceived exertion and physiologic markers during arm exercise with able-bodied participants and participants with poliomyelitis.

Objective

To investigate the strength of the relationship between ratings of perceived exertion (RPE) and oxygen uptake (V?o₂), heart rate, ventilation (V?e) and power output (PO) during an arm-crank ramped exercise test to volitional exhaustion in men and women who differed in physical status.

Design

Each participant completed an arm-crank ramp exercise test to volitional exhaustion. PO was increased by 15W·min⁻¹ and 6W·min⁻¹ for men and women able-bodied participants, respectively; for the poliomyelitis participants, 9W·min⁻¹ and 6W·min⁻¹ increments were used for men and women, respectively.

Setting

Laboratory facilities at a university.

Participants

Able-bodied participants (n=16; 9 men, 7 women) and participants with poliomyelitis (n=15, 8 men, 7 women) volunteered for the study.

Main Outcome Measures

Strength of the relationship (R² values) between RPE and V?o₂, heart rate, V?e and PO.

Results

There were significantly higher values for maximum V?o₂ and maximum PO for able-bodied men compared with their counterparts with poliomyelitis (P<.05). However, when the data were controlled for age, there were no significant differences in these values (P>.05). Similar results were observed for the women who were able-bodied as well as for the women who had poliomyelitis (P>.05). The relationships between heart rate and RPE and V?e and RPE for able-bodied patients and patients with poliomyelitis were similar (R²>.87). The relationship between V?o₂ and RPE was stronger in the able-bodied participants compared wih the participants with poliomyelitis, regardless of sex (P<.05). However, when the data were controlled for age, there was no significant difference in the strength of this relationship between able-bodied participants and those with poliomyelitis, regardless of sex (P>.05).

Conclusions

RPE is strongly related to physiologic markers of exercise intensity during arm exercise, irrespective of sex or participant's poliomyelitis status.     

A Preliminary Study to Examine the Effects of Aerobic and Therapeutic (Nonaerobic) Exercise on Cardiorespiratory Fitness and Coronary Risk Reduction in Stroke Survivors

Rimmer JH, Rauworth AE, Wang EC, Nicola TL, Hill B. A preliminary study to examine the effects of aerobic and therapeutic (nonaerobic) exercise on cardiorespiratory fitness and coronary risk reduction in stroke survivors.

Objectives

To compare the effects of 3 different exercise training regimens on cardiorespiratory fitness and coronary risk factor reduction in subjects with unilateral stroke.

Design

A cluster assignment by residential location repeated-measures design.

Setting

University-based medical center.

Participants

Fifty-five subjects with unilateral ischemic stroke were assigned to the following groups: intensity (n=18), duration (n=19), and therapeutic exercise (n=18).

Intervention

A 14-week intervention with subjects randomized to 1 of 3 interventions: (1) moderate intensity, shorter duration (MISD) exercise (gradually increasing exercise intensity while keeping exercise duration constant at 30 min), (2) low-intensity, longer duration (LILD) exercise (gradually increasing duration to 60 min while keeping exercise intensity constant), or (3) conventional therapeutic exercise (TE) consisting mainly of strength, balance, and range of motion activities. All groups exercised 3 days per week.

Main Outcome Measures

Peak oxygen consumption (Vo₂peak), submaximal oxygen consumption (V?o₂), lipid panel, and resting blood pressure.

Results

The MISD group attained more favorable effects on systolic (P<.04) and diastolic blood pressure (P<.002) and total cholesterol (TC) (P<.036) compared with LILD and TE groups. Both MISD (P<.029) and LILD (P<.045) showed significant reductions in triglycerides compared with TE (P<.029). There was no significant change in Vo₂peak and submaximal V?o₂ in any of the groups.

Conclusions

Overall, both MISD and LILD conditions achieved greater clinical and significant gains in coronary risk reduction compared with TE.     

Improvement in aerobic fitness during rehabilitation after hip fracture

Mendelsohn ME, Overend TJ, Connelly DM, Petrella RJ. Improvement in aerobic fitness during rehabilitation after hip fracture.

Objective

To evaluate the effect of an upper-body exercise program on cardiorespiratory fitness in older adults with hip fracture during inpatient rehabilitation.

Design

Randomized controlled trial using a convenience sample.

Setting

An inpatient rehabilitation unit.

Participants

Twenty older patients (age, 81.3±7.2y; 14 women).

Intervention

Patients were randomly assigned to a control group (n=10) or a training group (n=10). Both groups attended physical and occupational therapy sessions 5 times a week during rehabilitation (mean length of stay, 32.9±5.3d). Patients in the training program used an arm crank ergometer 3 times a week for 4 weeks.

Main Outcome Measure

Peak oxygen consumption (Vo₂peak).

Results

Vo₂peak increased significantly in the training group (8.9±1.4 to 10.8±1.7mL·kg⁻¹·min⁻¹) and did not change in the control group (8.9±1.2 to 8.8±1.6mL·kg⁻¹·min⁻¹). At discharge, both groups were significantly improved in all functional outcome measures (Timed Up & Go [TUG] test, Berg Balance Scale [BBS], FIM instrument, two-minute walk test [2MWT], and ten-minute walk test [10MWT]). The training group performed significantly better in mobility (TUG, 2MWT, 10MWT) and balance (BBS) compared with the control group. There was a significant correlation between Vo₂peak and the 2MWT (r=.81) and 10MWT (r=.85) in the training group at discharge.

Conclusions

The upper-body exercise program had a significant effect on aerobic power. Our results suggest that aerobic endurance exercise should be integrated into standard rehabilitation to enhance patients’ aerobic fitness and mobility after hip fracture surgery.     

Predictive Equations Overestimate Resting Metabolic Rate in Survivors of Chronic Stroke

ObjectiveTo measure resting metabolic rate (RMR) in survivors of chronic (>3 months prior) stroke (mean ± SEM age, 61±7.5 years) and to compare to predicted RMR using predictive equations in adults without stroke.DesignCross-sectional study.SettingHospital.ParticipantsSurvivors of stroke (N=71).InterventionNot applicable.Main Outcome MeasuresRMR was measured by indirect calorimetry. Participants underwent a total body dual-energy x-ray absorptiometry scan and treadmill test for peak oxygen consumption (V?o₂peak). RMR was calculated using 9 established equations.ResultsRMR measured (1552±319 kcal/d) was significantly lower than 9 predicted RMR values (all P<.001), with the best being McArdle-Katch (1652±233 kcal/d), Livingston (1677±230 kcal/d), and Mifflin (1707±242 kcal/d). The Institute of Medicine of the National Academies (2437±386 kcal/d) had the largest discrepancy with measured RMR. Predicted RMR determined with 8 of 9 equations was between 9% and 18% greater than measured RMR. Appendicular lean mass (r=0.64, P<.001), total lean mass (r=0.64, P<.001), and V?o₂peak (r=0.41, P<.001) were associated with measured RMR.ConclusionsRMR predictive equations established in adults without stroke are not appropriate for the population with stroke population, indicating the need to measure RMR until a more accurate predictive equation is developed. This could support modifications to nutritional intake guidelines in patients with conditions of muscle atrophy. If measurement of RMR is not feasible, the Katch-McArdle equation should be used to estimate RMR in a patient with stroke because on average it provides the lowest percentage overestimate compared with other equations.     

Predictors of cardiometabolic risk among adults with cerebral palsy

Peterson MD, Haapala HJ, Hurvitz EA. Predictors of cardiometabolic risk among adults with cerebral palsy.ObjectiveTo examine the independent association between various anthropometric indicators and standard clinical markers of cardiometabolic health risk among adults with cerebral palsy (CP).DesignCross-sectional study.SettingClinical center for CP treatment and rehabilitation.ParticipantsAdults with CP (N=43) with a mean age ± SD of 37.3±13.2 years, and Gross Motor Function Classification System (GMFCS) levels of I?V.InterventionsNot applicable.Main Outcome MeasuresAdults with CP were assessed for body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR), waist-to-height ratio (WtHR), and serum lipid profiles. Data were analyzed with multiple regression analysis and general linear models, and are reported as means ± SDs.ResultsMean BMI was 29.1±7.8kg/m². BMI was not associated with any measures of cardiometabolic risk. Using GMFCS categories (2 groups: GMFCS levels I–III and IV–V), BMI was significantly lower among GMFCS levels IV–V (24.2±6.2kg/m²) versus GMFCS levels I–III (30.1±7.6kg/m²). WC and WtHR were not correlated with any cardiometabolic outcomes. Conversely, measures of WHR were independently associated with various indices of risk, including total cholesterol to high-density lipoprotein (HDL) cholesterol ratio (r=.45; P<.05), HDL cholesterol (r=–.51; P<.01), and triglycerides (r=.40; P<.05), suggesting that greater WHR was indicative of elevated risk.ConclusionsIt is likely that WHR represents a stronger predictor of risk, because this measure was robustly and independently associated with 3 primary clinical markers of cardiometabolic health in adults with CP.     

Anticipating maximal or submaximal exercise: no differences in cardiopulmonary responses

Background: Anticipation before the start of exercise may influence the cardiopulmonary responses during exercise. If anticipation influences the responses differently with maximal and submaximal exercises, normative values for submaximal responses will not be comparable unless exercise has been continued to the same end point. Methods: Twelve healthy subjects (five men) aged 18–27 years had a maximal exercise test and a submaximal exercise test on a cycle ergometer on different days and in random order. They were not aware of the specific purpose of the study and were informed 15 min before the tests whether it should be maximal or submaximal. Workload increased with 15 W min^?1 until exhaustion or to 80% of predicted maximal heart rate (HR). HR, oxygen uptake (VO₂), carbon dioxide production (VCO₂), minute ventilation (V_E) and tidal volume (V_T) were averaged over 20 s intervals. Linear regression of the HR–VO₂ relationship and quadratic regression of the V_T–V_E relationship were performed for each individual, and the regression coefficients for maximal and submaximal tests were compared. Results: The regression models described the V_T–V_E responses with a R² > 0·85 in 23 of 24 tests, and the HR‐VO₂ responses with a R² > 0·90 in all tests. The regression coefficients of the relationships were not significantly different with maximal and submaximal exercises. Conclusion: Anticipation appears not to influence the responses to progressive maximal and submaximal exercise tests with the same rate of increase in load. Normative values at submaximal exercise levels are not influenced by the targeted end point of exercise.     

Upper Limb Energy Demand During Unilateral Arm Crank Submaximal Exercise Testing in Individuals With Chronic Stroke

ObjectiveTo investigate upper limb (UL) energy demand during unilateral arm crank submaximal exercise testing in individuals with stroke compared with healthy controls and the relationship between UL energy demand and UL activity in individuals with stroke.DesignCross-sectional, observational study.SettingResearch laboratory.ParticipantsIndividuals with chronic stroke (n=14) and controls (n=12), matched for age, sex, and body mass index (N=26).InterventionsNot applicable.Main Outcome MeasuresUL energy demand was measured as peak oxygen consumption (V̇o₂)/peak load during unilateral arm crank submaximal exercise testing. UL activity was measured using the Box and Block Test (BBT) and Grooved Pegboard Test (GPT).ResultsThe energy demand of the paretic side compared with the nonparetic side of the stroke group was 0.43 mL/kg/min/W (95% confidence interval, 0.03-0.83, P=.005) greater than the dominant compared with the nondominant side of the control group. The median difference between sides in peak V̇o₂/peak load was 52% for the group with stroke compared with 11% for the control group. Positive correlations between the median percentage difference between the paretic and the nonparetic side of peak V̇o₂/peak load and BBT were 0.72 (P=.004) and of V̇o₂/peak load and GPT was 0.77 (P=.002).ConclusionsThe higher energy demand of the paretic UL during unilateral arm crank submaximal exercise testing than the nonparetic and both UL of the controls together with the strong relationship between energy demand and UL activity suggest that the energy demand of the paretic UL has the potential to affect real-life UL activity after stroke.