Exercise testing protocol using a roller system for manual wheelchair users with spinal cord injury

Objective: Determine the validity and reliability of an exercise testing protocol to evaluate cardiorespiratory measures in manual wheelchair users (MWUs) with spinal cord injury (SCI) using a roller-based (RS) wheelchair system.

Design: Repeated measures within-subject design.

Setting: Community-based research laboratory.

Participants: Ten adults with SCI requiring the use of a manual wheelchair.

Interventions: Not applicable.

Outcome measures: Cardiorespiratory measures (peak oxygen consumption [VO₂peak], respiratory exchange ratio [RER], pulmonary ventilation [VE], energy expenditure [EE], heart rate [HR], accumulated kilocalories [AcKcal]) and perceived exertion (RPE) were measured during three separate maximal exercise tests using an arm crank ergometer (ACE) and an RS.

Results: At maximal exertion, there were no significant differences in variables between groups, with moderate-to-strong correlations (P?<?0.05, r?=?0.79–0.90) for VO₂, HR, RPE, AcKcal, and rate of EE between RS and ACE trials. Significant moderate-to-strong correlations existed between RS trials for VO₂, AcKcal, rate of EE, and peak power output (P?<?0.01, r?=?0.77–0.97).

Conclusions: VO_2peak was highly correlated between ACE and RS trials and between the two RS trials, indicating the RS protocol to be reliable and valid for MWUs with SCI. Differences in perceived exertion and efficiency at submaximal workloads and maximal pulmonary ventilation at peak workloads indicated potential advantages to using the RS.     

Longitudinal relationship between wheelchair exercise capacity and life satisfaction in patients with spinal cord injury: A cohort study in the Netherlands

Abstract

Objective

To examine the relationship between wheelchair exercise capacity and life satisfaction in persons with spinal cord injury from the start of active inpatient rehabilitation up to 5 years after discharge.

Design

Prospective cohort study.

Subjects

Persons with spinal cord injury, aged 18–65 years, and wheelchair dependent at least for long distances.

Method

Measurements at the start of active rehabilitation, after 3 months, at discharge from inpatient rehabilitation, and 1 and 5 years after discharge. A peak wheelchair exercise test was performed to record peak oxygen uptake (VO_2peak) and peak power output (PO_peak). Life satisfaction was measured as current life satisfaction and change of life satisfaction in comparison with life after spinal cord injury. Relationships between (changes in) exercise capacity and (changes in) life satisfaction were analyzed random coefficient analysis, corrected for possible confounders (age, gender, level of lesion, functional status, secondary impairments, pain, and sports activity) if necessary.

Results

Of 225 persons included, 130 attended two or more peak exercise tests, who were include in the analyses. Mean age at start was 39 years, 75% were male, 73% had paraplegia, and 76% had a traumatic lesion. Mean PO_peak increased during the study from 32.9 to 55.9 Watts, mean VO_2peak from 1.02 to 1.38 l/minute, and mean life satisfaction from 5.7 to 7.8. An increase of PO_peak with 10 W was associated with a 0.3-point increase of life satisfaction (P = 0.01). An increase of VO_2peak with 0.1 l/minute was associated with a 0.1-point increase of life satisfaction (P = 0.049).

Conclusion

High(er) wheelchair exercise capacity is related to high(er) life satisfaction in spinal cord injury patients.     

Assessment of Cardiorespiratory and Metabolic Responses in Women with Obesity After Surgically Induced Weight Loss: Results from a Pilot Study

Purpose

Bariatric surgery is effective in controlling severe obesity. However, studies investigating the impact of surgically induced weight loss on cardiorespiratory and metabolic responses during maximal effort are controversial. The aim of this study was to assess cardiorespiratory and metabolic responses in women with obesity after bariatric surgery.

Materials and Methods

We performed a secondary analysis on data from a pilot study with women with obesity submitted to bariatric surgery and who did not participate in a controlled physical training program. Anthropometry, pulmonary function (spirometry), and cardiorespiratory fitness (cardiopulmonary exercise testing [CPX]) were assessed before and after bariatric surgery.

Results

Thirty-four women were included (38.7 ± 9.6 years, body mass index = 44.1 ± 6.3 kg/m²). Postoperative assessment was conducted 9.4 ± 2.7 months after surgery. After surgery, we observed a reduction in all anthropometric measurements (mean loss of 28.6 kg, p < 0.001), and improvement in spirometry values (p < 0.001). Relative VO_2peak (mL/kg/min) increased slightly (Δ = 1.7; p = 0.06); however, absolute VO_2peak (L/min) reduced significantly (Δ =  − 0.398; p < 0.001). We also observed an increase of 1.3 min (p < 0.001) in CPX duration, a reduction of 11.3 bpm (p < 0.001) in resting heart rate, and a decrease of systolic (p = 0.02) and diastolic (p < 0.001) blood pressures at peak effort.

Conclusion

Surgically induced weight loss without exercise training improved cardiac reserve, ventilatory response, blood pressure, and resting heart rate. Cardiorespiratory fitness reflected by relative VO_2peak increased slightly, despite increased tolerance to CPX.

Graphical abstract

     

Test-retest reliability,minimal detectable change and minimal clinically important differences in modified shuttle walk test in children and adolescents with cystic fibrosis

BackgroundIn youths with cystic fibrosis (CF) the modified shuttle walk test (MSWT) has been shown to be useful for assessing exercise tolerance; however, no studies to date have evaluated the reliability of MSWT, the minimal detectable change (MDC) and the minimal clinically important differences (MCID) for the MSWT distance for children and adolescents with CF.MethodsTest-retest reliability: 35 CF patients and 34 healthy controls performed two MSWTs (separated by 2–4 days). MCID: 33 patients were invited to participate in a 6-week home-based exercise program consisting of 30–60-min sessions, 5 days a week.ResultsThe test-retest reliability of the MSWT distance for children and adolescents with CF was excellent, obtaining a MDC₉₀ and MDC₉₅ of 97.08 m and 115.32 m, respectively. The test-retest reliability also was excellent in healthy controls, founding a MDC₉₀ and MDC₉₅ of 69.12 m and 82.11 m, respectively. The ROC curve analysis established (with a sensitivity of 82% and specificity of 76%) that a change of 60 m represented MCID.ConclusionsThe MSWT is a reliable tool to measure of exercise tolerance in children/adolescents with CF and those without CF. We propose a change in the score of at least 97.08 m (MDC₉₀) as the most appropriate value for assessing the exercise response of children and adolescents with CF, given that this value exceeds the MCID based on the children's perception.     

Test-retest reliability at the item level and total score level of the Norwegian version of the Spinal Cord Injury Falls Concern Scale (SCI-FCS)

Objectives: Translation of the Spinal Cord Injury Falls Concern Scale (SCI-FCS), and investigation of test-retest reliability on item-level and total-score-level.

Design: Translation, adaptation and test-retest study.

Setting: A specialized rehabilitation setting in Norway.

Participants: Fifty-four wheelchair users with a spinal cord injury. The median age of the cohort was 49 years, and the median number of years after injury was 13.

Interventions/measurements: The SCI-FCS was translated and back-translated according to guidelines. Individuals answered the SCI-FCS twice over the course of one week. We investigated item-level test-retest reliability using Svensson's rank-based statistical method for disagreement analysis of paired ordinal data. For relative reliability, we analyzed the total-score-level test-retest reliability with intraclass correlation coefficients (ICC_2.1), the standard error of measurement (SEM), and the smallest detectable change (SDC) for absolute reliability/measurement-error assessment and Cronbach's alpha for internal consistency.

Results: All items showed satisfactory percentage agreement (≥69%) between test and retest. There were small but non-negligible systematic disagreements among three items; we recovered an 11–13% higher chance for a lower second score. There was no disagreement due to random variance. The test-retest agreement (ICC_2.1) was excellent (0.83). The SEM was 2.6 (12%), and the SDC was 7.1 (32%). The Cronbach's alpha was high (0.88).

Conclusion: The Norwegian SCI-FCS is highly reliable for wheelchair users with chronic spinal cord injuries.     

Cardiovascular response to peak voluntary exercise in males with cervical spinal cord injury

Context/Objective: Traumatic damage to the cervical spinal cord is usually associated with a disruption of the autonomic nervous system (ANS) and impaired cardiovascular control both during and following exercise. The magnitude of the cardiovascular dysfunction remains unclear. The aim of the current study was to compare cardiovascular responses to peak voluntary exercise in individuals with tetraplegia and able-bodied participants.

Design: A case-control study.

Subjects: Twenty males with cervical spinal cord injury (SCI) as the Tetra group and 27 able-bodied males as the Control group were included in the study.

Outcome Measures: Blood pressure (BP) response one minute after the peak exercise, peak heart rate (HR_peak), and peak oxygen consumption (VO_2peak) on an arm crank ergometer were measured. In the second part of the study, 17 individuals of the Control group completed the Tetra group's workload protocol with the same parameters recorded.

Results: There was no increase in BP in response to the exercise in the Tetra group. Able-bodied individuals exhibited significantly increased post-exercise systolic BP after the maximal graded exercise test (123±16%) and after completion of the Tetra group's workload protocol (114±11%) as compared to pre-exercise. The Tetra group VO_2peak was 59% and the HR_peak was 73% of the Control group VO_2peak and HR_peak, respectively.

Conclusions: BP did not increase following maximal arm crank exercise in males with a cervical SCI unlike the increases observed in the Control group. Some males in the Tetra group appeared to be at risk of severe hypotension following high intensity exercise, which can limit the ability to progressive increase and maintain high intensity exercise.     

Reliability Of Arm Wingate Anaerobic Testing In Persons With Complete Paraplegia

Abstract

Background: Accurate, reliable assessment of upper extremity muscular power in persons with paraplegia caused by spinal cord injury (SCI) would provide an objective indication of their ability to generate the forces necessary for the performance of daily activities. Wingate Anaerobic Testing (WAnT) consists of a 30-second sprint test on a cycle ergometer and has been used widely in both athletic and research settings.

Purpose: To examine test-retest reliability of arm WAnT performance in persons with complete SCI and paraplegia.

Methods: Forty-three participants with thoracic-level paraplegia (T2 through T12) performed 2 trials of arm WAnT with 2 to 7 days between each trial. Testing was performed using a Monarch 834E ergometer with participants seated in their wheelchairs. Participants were directed to crank at maximal pace for 30 seconds against a resistance load equivalent to 3.5% of their body mass. The SMI OptoSensor 2000 system was used to determine values of peak power (P_peak), mean power (P_mean), minimum power, and rate of fatigue, which were compared between trials using 1-way analysis of variance for repeated measures. Coeffi cients of determination (r₂) were calculated between trials for P_peak and P_mean.

Results: No significant diffe rence was found between trials for any of the power output variables. Regression analysis ind icat ed that P_peak and P_mean were closely associated between the 2 trials (r₂= 0.92 and 0.94, respectively).

Conclusion: Arm WAnT is a reliable measurement tool for the assessment of upper extremity muscular power in persons with complete paraplegia.     

Physiological Responses to Exergaming After Spinal Cord Injury

Purpose:

To investigate whether exergaming satisfies guideline-based intensity standards for exercise conditioning (40%/50% oxygen uptake reserve [VO₂R] or heart rate reserve (HRR), or 64%/70% of peak heart rate [HR_peak]) in persons with paraplegia.

Methods:

Nine men and women (18-65 years old) with chronic paraplegia (T1-L1, AIS A-C) underwent intensity-graded arm cycle exercise (AE) to evaluate VO2_peak and HR_peak. On 2 randomized nonconsecutive days, participants underwent graded exercise using a custom arm cycle ergometer that controls the video display of a Nintendo Gamecube (GameCycle; Three Rivers Holdings LLC, Mesa, AZ) or 15 minutes of incrementally wrist-weighted tennis gameplay against a televised opponent (XaviX Tennis System; SSD Co Ltd, Kusatsu, Japan).

Results:

GameCycle exergaming (GCE) resistance settings ≥0.88 Nm evoked on average ≥50% VO₂R. During XaviX Tennis System exergaming (XTSE) with wrist weights ≥2 lbs, average VO₂ reached a plateau of ~40% VO₂R. Measurements of HR were highly variable and reached average values ≥50% HRR during GCE at resistance settings ≥0.88 Nm. During XTSE, average HR did not reach threshold levels based on HRR for any wrist weight (20%-35% HRR).

Conclusions:

On average, intensity responses to GCE at resistance setting ≥0.88 Nm were sufficient to elicit exercise intensities needed to promote cardiorespiratory fitness in individuals with SCI. The ability of XTSE to elicit cardiorespiratory fitness benefits is most likely limited to individuals with very low fitness levels and may become subminimal with time if used as a conditioning stimulus.     

Cardiorespiratory fitness is a marker of cardiovascular health in renal transplanted children

Children with renal transplants (TX) are at increased risk of cardiovascular (CV) disease. Study objectives were to assess the level of cardiorespiratory fitness (CR fitness) and daily physical activity (PA) in renal TX children and adolescents in relation to traditional cardiovascular risk factors. Laboratory testing included assessment of CR fitness by treadmill exercise testing (VO_2peak), 24-h ambulatory blood-pressure (ABPM) measurement, oral glucose tolerance test (OGTT), anthropometrics and measurement of lipid levels. PA was self-reported by questionnaire. Twenty-two TX patients with a median (range) age 14.5 (9–18) years were tested. Median V0_2peak was 66% (36–97) of the expected values compared with controls. Nineteen (86%) children reported <60 min of daily moderate to vigorous physical activity (MVPA). Sixteen (73%) were hypertensive and 8 (34%) were overweight or obese. Four children fulfilled the criteria for a metabolic syndrome. Children with at least 2 of the 3 metabolic risk factors (hypertension, overweight, and glucose intolerance, n = 7) achieved significantly lower VO_2peak compared with those with one or none of these factors (median V0_2peak 45% and 73% of the expected values respectively, p = 0.003). Renal TX children and adolescents have severely impaired CR fitness and PA. Reduced CR fitness was associated with the clustering of CV risk factors. Routine counseling for increased PA is strongly recommended.     

Reliability and Validity of Physiological Data Obtained Within a Cycle-Run Transition Test in Age-Group Triathletes

This study examined the validity and reliability of a sequential “Run-Bike-Run” test (RBR) in age-group triathletes. Eight Olympic distance (OD) specialists (age 30.0 ± 2.0 years, mass 75.6 ± 1.6 kg, run VO_2max 63.8 ± 1.9 ml· kg^-1· min^-1, cycle VO_2peak 56.7 ± 5.1 ml· kg^-1· min^-1) performed four trials over 10 days. Trial 1 (TRVO_2max) was an incremental treadmill running test. Trials 2 and 3 (RBR₁ and RBR₂) involved: 1) a 7-min run at 15 km· h^-1 (R₁) plus a 1-min transition to 2) cycling to fatigue (2 W· kg^-1 body mass then 30 W each 3 min); 3) 10-min cycling at 3 W· kg^-1 (B_submax); another 1-min transition and 4) a second 7-min run at 15 km· h^-1 (R₂). Trial 4 (TT) was a 30-min cycle - 20-min run time trial. No significant differences in absolute oxygen uptake (VO₂), heart rate (HR), or blood lactate concentration ([BLA]) were evidenced between RBR₁ and RBR₂. For all measured physiological variables, the limits of agreement were similar, and the mean differences were physiologically unimportant, between trials. Low levels of test-retest error (i.e. ICC <0.8, CV<10%) were observed for most (logged) measurements. However [BLA] post R₁ (ICC 0.87, CV 25.1%), [BLA] post B_submax (ICC 0.99, CV 16.31) and [BLA] post R₂ (ICC 0.51, CV 22.9%) were least reliable. These error ranges may help coaches detect real changes in training status over time. Moreover, RBR test variables can be used to predict discipline specific and overall TT performance. Cycle VO_2peak, cycle peak power output, and the change between R₁ and R₂ (deltaR₁R₂) in [BLA] were most highly related to overall TT distance (r = 0.89, p < 0. 01; r = 0.94, p < 0.02; r = 0.86, p < 0.05, respectively). The percentage of TR VO_2max at 15 km· h^-1, and deltaR₁R₂ HR, were also related to run TT distance (r = -0.83 and 0.86, both p < 0.05).

Key points

• It is extremely important to ensure that the measurements made as part of research or athlete support work are adequately reliable and valid.
• The modified Millet triathlete “Run-Bike-Run” (RBR) test allows both for important physiological variables that are normally obtained from isolated tests (such as cycle VO_2peak and peak power output) to be determined, and for measurement of the extent to which an athlete adapts to a cycle-run transition (T2).
• The data reported in this paper regarding the test-retest reliability of the modified RBR, and its validity relative to cycle-run time-trial performance in male age-group triathletes, may help coaches determine the extent to which changes on test measures are likely due to training adaptation rather than to measurement error.

Key words: Multi-discipline, reproducibility, time-trial, test, adaptation     

Clinical utility of the oxygen uptake efficiency slope in cystic fibrosis patients

BackgroundThe present study investigated the validity and the reliability of the oxygen uptake efficiency slope (OUES) as a determinant of exercise tolerance in adults with cystic fibrosis (CF).Methods31 CF patients and 34 healthy controls performed a maximal incremental cycle test with respiratory gas-exchange measurements. OUES was calculated from data taken from different percentages of the entire exercise duration, including 80% (OUES₈₀) and 100% (OUES₁₀₀). Peak oxygen uptake (VO_2peak) and gas exchange threshold (GET) were also determined. The agreement between submaximal parameters and VO_2peak was assessed using Bland Altman plots. Test retest reliability was evaluated in CF patients using absolute (SEM) and relative indices (ICC).ResultsOn the contrary to the GET, which was undetectable in 16% of the CF patients, the OUES was easily determined in all patients. Among all the submaximal variables, OUES₈₀ had the best reliability (ICC = 0.94, SEM = 7.3%) and agreement with VO_2peak (r² = 0.83, P < 0.01; limits of agreement: ± 365 mL min^− 1) and did not differ from OUES₁₀₀.ConclusionsOUES₈₀ is a reliable and more useful submaximal parameter than the GET and may find use in the interpretation of exercise studies in CF patients who are unable to perform maximal exercise.     

Development and evaluation of a gyroscope-based wheel rotation monitor for manual wheelchair users

Abstract

Objective

To develop and evaluate a wireless gyroscope-based wheel rotation monitor (G-WRM) that can estimate speeds and distances traveled by wheelchair users during regular wheelchair propulsion as well as wheelchair sports such as handcycling, and provide users with real-time feedback through a smartphone application.

Methods

The speeds and the distances estimated by the G-WRM were compared with the criterion measures by calculating absolute difference, mean difference, and percentage errors during a series of laboratory-based tests. Intraclass correlations (ICC) and the Bland–Altman plots were also used to assess the agreements between the G-WRM and the criterion measures. In addition, battery life and wireless data transmission tests under a number of usage conditions were performed.

Results

The percentage errors for the angular velocities, speeds, and distances obtained from three prototype G-WRMs were less than 3% for all the test trials. The high ICC values (ICC (3,1) > 0.94) and the Bland–Altman plots indicate excellent agreement between the estimated speeds and distances by the G-WRMs and the criterion measures. The battery life tests showed that the device could last for 35 hours in wireless mode and 139 hours in secure digital card mode. The wireless data transmission tests indicated less than 0.3% of data loss.

Conclusion

The results indicate that the G-WRM is an appropriate tool for tracking a spectrum of wheelchair-related activities from regular wheelchair propulsion to wheelchair sports such as handcycling. The real-time feedback provided by the G-WRM can help wheelchair users self-monitor their everyday activities.     

Longitudinal relationship between wheelchair exercise capacity and life satisfaction in patients with spinal cord injury: A cohort study in the Netherlands

Objective

To examine the relationship between wheelchair exercise capacity and life satisfaction in persons with spinal cord injury from the start of active inpatient rehabilitation up to 5 years after discharge.

Design

Prospective cohort study.

Subjects

Persons with spinal cord injury, aged 18–65 years, and wheelchair dependent at least for long distances.

Method

Measurements at the start of active rehabilitation, after 3 months, at discharge from inpatient rehabilitation, and 1 and 5 years after discharge. A peak wheelchair exercise test was performed to record peak oxygen uptake (VO_2peak) and peak power output (PO_peak). Life satisfaction was measured as current life satisfaction and change of life satisfaction in comparison with life after spinal cord injury. Relationships between (changes in) exercise capacity and (changes in) life satisfaction were analyzed random coefficient analysis, corrected for possible confounders (age, gender, level of lesion, functional status, secondary impairments, pain, and sports activity) if necessary.

Results

Of 225 persons included, 130 attended two or more peak exercise tests, who were include in the analyses. Mean age at start was 39 years, 75% were male, 73% had paraplegia, and 76% had a traumatic lesion. Mean PO_peak increased during the study from 32.9 to 55.9 Watts, mean VO_2peak from 1.02  to 1.38 l/minute, and mean life satisfaction from 5.7 to 7.8. An increase of PO_peak with 10 W was associated with a 0.3-point increase of life satisfaction (P = 0.01). An increase of VO_2peak with 0.1 l/minute was associated with a 0.1-point increase of life satisfaction (P = 0.049).

Conclusion

High(er) wheelchair exercise capacity is related to high(er) life satisfaction in spinal cord injury patients.     

Adaptation to reduced lung function in children and young people with spinal deformity

BackgroundSevere scoliosis can affect respiratory function in growing patients and produce cardiopulmonary complications, leading to significant morbidity. The development of spinal deformity may impact on young patients’ level of function and reported quality of life (QOL). The aim of this study was to investigate the relationship between lung function, exercise capacity and quality of life in young patients with spinal deformity.MethodsThis is a retrospective analysis of 104 patients (31% male, 69% female with mean age 14.9yrs). 77% of patients had an adolescent idiopathic scoliosis, with the remainder having other scoliosis diagnoses or Scheuermann’s kyphosis. Principal outcomes included Spirometry [FEV₁, FVC], Whole Body Plethysmography, Cardiopulmonary Exercise Testing [CPET] and patient outcome questionnaires (with SRS-22). CPET measures included maximal exercise capacity [VO_2peak] as well as VO₂ at ventilatory threshold [VT] expressed as %predicted VO_2max-a measure of physical conditioning, and minute ventilation [V_E] from which breathing reserve [BR] could be calculated.ResultsMean (±SD) main thoracic scoliosis was 59.9⁰ (±15.2⁰), and mean kyphosis in those with Scheuermann’s condition was 95.3⁰ (±11.5⁰). No correlation was elicited between FEV₁ or FVC (%predicted) and VO_2peak (%predicted) in this patient cohort. Greater thoracic curves were associated with lower FEV₁ (%predicted), r = −0.343, p = 0.001, FVC (%predicted), r = −0.307, p = 0.003 and BR (%) at the end of exercise (r = −0.-0.459, p < 0.001). The patient cohort had a mean (sd) VO₂peak of 98(17) %predicted, with greater VO₂peak levels recorded in female subjects, those of younger age and those with higher scoliosis angles. Those with better lung function [FEV₁ (%predicted)] had better BR (%) at the end of exercise (r = 0.483, p < 0.001). SRS-22 scores correlated significantly with VO_2peak (%predicted) (total SRS-22 versus VO_2peak (%predicted), r = 0.336, p = 0.002).ConclusionLarger thoracic scoliotic curves are associated with poorer lung function but better exercise capacity, likely related to higher levels of physical conditioning. Higher QOL scores were recorded in patients who had greater VO_2peak levels, suggesting that exercise capacity may be a protective factor for emotional well-being in patients with spinal deformity.     

Aquatic,deep water peak VO2 testing for individuals with spinal cord injury

Objective: To determine the reliability of peak VO₂ testing for individuals with spinal cord injury (SCI) in deep water and on land; and to examine the relationship between these two testing conditions.

Design: Reliability study.

Setting: Comprehensive rehabilitation center in Baltimore, MD, USA.

Participants: 17 participants (13 men, 4 women) with motor complete and incomplete SCI. Participants were randomized into either aquatic or arm cycle ergometer first measurements.

Intervention: Pilot study to assess peak VO₂.

Outcome measures: Peak VO₂ measured with metabolic cart in supported deep water with the addition of Aquatrainer® connection, and on land with arm cycle ergometer. Two trials were conducted for each condition with 48?h separating each test.

Results: Peak oxygen consumption reliability was statistically significant for both conditions, aquatic (r?=?0.93, P?<?0.001) and arm cycle ergometry (r?=?0.96, P?<?0.001). Additionally, aquatic and arm cycle peak VO₂ correlation existed (r?=?0.72, P?<?0.001). For these 17 participants, lower extremity motor score influenced supported, deep water peak VO₂, B?=?0.57, P?<?0.02, whereas age, sex, and weight did not impact deep water or ergometer values.

Conclusion: Determining peak VO₂ for individuals with SCI is highly reproducible for arm cycle ergometry and in deep water assessment. Additionally, aquatic, deep water peak VO₂ testing is valid when compared to arm cycle ergometry. Although the peak VO₂ relationship between deep water and arm cycle ergometry is high, variance in the two conditions does exist. Therefore, it is important to assess peak VO₂ via the same exercise modality utilized in the treatment intervention.     

Relationship between Fat Oxidation and Lactate Threshold in Athletes and Obese Women and Men

The first aim of this study was to determine the exercise intensity that elicited the highest rate of fat oxidation in sedentary, obese subjects (OB; n=10 men, n=10 women) compared with endurance athletes (AT; n=10 men, n=10 women). The second aim was to investigate the relationship between VO₂ at the intensity eliciting the highest rate of fat oxidation and the corresponding VO₂ at the lactate threshold. Peak oxygen consumption (VO_2peak) was determined in 20 AT and 20 OB using an incremental exercise protocol on a cycle ergometer. Based on their VO_2peak values, subjects completed a protocol requiring them to exercise for 20 min at three different workloads (55, 65 and 75% VO_2peak), randomly assigned on two separate occasions. The oxidation rates of fat and carbohydrate were measured by indirect calorimetry. The highest rates of fat oxidation were at 75 % VO_2peak (AT), and at 65 % VO_2peak (OB). The rate of fat oxidation was significantly higher in AT (18.2 ± 6.1) compared with OB women (10.6 ± 4.5 kJ min^-1·kg^-1) (p < 0.01). There was no significant difference in the rate of fat oxidation for the men (AT 19.7 ± 8.1 vs. OB 17.6 ± 8.2 kJ min^-1·kg^-1). AT reached LT at a significantly (p < 0.01) higher exercise intensity expressed in VO_2peak than obese subjects (AT women 76.4 ± 0.1, men 77.3 ± 0.1 vs. OB women, 49.7 ± 0.1, men 49.5 ± 0.1% VO_2peak). A significant correlation was found between VO₂ at LT and VO₂ (L·min^-1) eliciting the maximal rate of fat oxidation in athletes (women; r = 0.67; p = 0.03; men: r = 0.75; p = 0.01) but not in the obese. In summary, we observed higher rates of fat oxidation at higher relative work rates in AT compared with OB. A significant correlation was found between LT and the exercise intensity eliciting a high rate of fat oxidation in AT (r=0.89; p < 0.01) but not in OB. Cardiorespiratory fitness, defined as VO_2peak, seems to be important in defining the relationship between a high rate of fat oxidation and LT.

Key Points

• Within the tested intensities of 55, 65 and 75% VO_2peak athletes reached higher rates of fat oxidation at higher relative work rates compared with obese subjects.
• We found in obese women and men the intensity of the highest rate of fat oxidation at 65% VO_2peak.
• Between the lactate threshold and the intensity eliciting a high rate of fat oxidation a significant correlation was found in athletes but not in obese subjects.

Key words: Exercise intensity, substrate utilization, obesity, lactate threshold     

Acute Cardiorespiratory and Metabolic Responses During Exoskeleton-Assisted Walking Overground Among Persons with Chronic Spinal Cord Injury

Background:

Lower extremity robotic exoskeleton technology is being developed with the promise of affording people with spinal cord injury (SCI) the opportunity to stand and walk. The mobility benefits of exoskeleton-assisted walking can be realized immediately, however the cardiorespiratory and metabolic benefits of this technology have not been thoroughly investigated.

Objective:

The purpose of this pilot study was to evaluate the acute cardiorespiratory and metabolic responses associated with exoskeleton-assisted walking overground and to determine the degree to which these responses change at differing walking speeds.

Methods:

Five subjects (4 male, 1 female) with chronic SCI (AIS A) volunteered for the study. Expired gases were collected during maximal graded exercise testing and two, 6-minute bouts of exoskeleton-assisted walking overground. Outcome measures included peak oxygen consumption (V̇O_2peak), average oxygen consumption (V̇O_2avg), peak heart rate (HR_peak), walking economy, metabolic equivalent of tasks for SCI (METs_sci), walk speed, and walk distance.

Results:

Significant differences were observed between walk-1 and walk-2 for walk speed, total walk distance, V̇O_2avg, and METs_sci. Exoskeleton-assisted walking resulted in %V̇O_2peak range of 51.5% to 63.2%. The metabolic cost of exoskeleton-assisted walking ranged from 3.5 to 4.3 METs_sci.

Conclusion:

Persons with motor-complete SCI may be limited in their capacity to perform physical exercise to the extent needed to improve health and fitness. Based on preliminary data, cardiorespiratory and metabolic demands of exoskeleton-assisted walking are consistent with activities performed at a moderate intensity.     

Good validity and reliability of the forgotten joint score in evaluating the outcome of total knee arthroplasty: A retrospective cross-sectional survey-based study

Background and purpose — When evaluating the outcome after total knee arthroplasty (TKA), increasing emphasis has been put on patient satisfaction and ability to perform activities of daily living. To address this, the forgotten joint score (FJS) for assessment of knee awareness has been developed. We investigated the validity and reliability of the FJS.

Patients and methods — A Danish version of the FJS questionnaire was created according to internationally accepted standards. 360 participants who underwent primary TKA were invited to participate in the study. Of these, 315 were included in a validity study and 150 in a reliability study. Correlation between the Oxford knee score (OKS) and the FJS was examined and test-retest evaluation was performed. A ceiling effect was defined as participants reaching a score within 15% of the maximum achievable score.

Results — The validity study revealed a strong correlation between the FJS and the OKS (intraclass correlation coefficient (ICC)?=?0.81, 95% CI: 0.77–0.85; p < 0.001). The test-retest evaluation showed almost perfect reliability for the FJS total score (ICC = 0.91, 95% CI: 0.88–0.94) and substantial reliability or better for individual items of the FJS (ICC? 0.79). We found a high level of internal consistency (Cronbach’s? = 0.96). The ceiling effect for the FJS was 16%, as compared to 37% for the OKS.

Interpretation — The FJS showed good construct validity and test-retest reliability. It had a lower ceiling effect than the OKS. The FJS appears to be a promising tool for evaluation of small differences in knee performance in groups of patients with good clinical results after TKA.     

Assessing Minimal Detectable Changes and Test-Retest Reliability of the Timed Up and Go Test and the 2-Minute Walk Test in Patients With Total Knee Arthroplasty

Background

Two-minute walk test (2MWT) and the Timed Up and Go test (TUG) are simple, quick, and can be applied in a short time as part of the routine medical examination. They were shown to be reliable and valid tests in many patient groups. The aims of the present study were: (1) to determine test-retest reliability of data for the TUG and 2MWT and (2) to determine minimal detectable change (MDC) scores for the TUG and 2MWT in patients with TKA.

Evaluation of activity monitors in manual wheelchair users with paraplegia

Abstract

Objective: The aim of this study was to evaluate the performance of SenseWear^® (SW) and RT3 activity monitors (AMs) in estimating energy expenditure (EE) in manual wheelchair users (MWUs) with paraplegia for a variety of physical activities.

Methods: Twenty-four subjects completed four activities including resting, wheelchair propulsion, arm-ergometry exercise, and deskwork. The criterion EE was measured by a K4b2 portable metabolic cart. The EE estimated by the SW and RT3 were compared with the criterion EE by the absolute differences and absolute percentage errors. Intraclass correlations and the Bland and Altman plots were also used to assess the agreements between the two AMs and the metabolic cart. Correlations between the criterion EE and the estimated EE and sensors data from the AMs were evaluated.

Results: The EE estimation errors for the AMs varied from 24.4 to 125.8% for the SW and from 22.0 to 52.8% for the RT3. The intraclass correlation coefficients (ICCs) between the criterion EE and the EE estimated by the two AMs for each activity and all activities as a whole were considered poor with all the ICCs smaller than 0.75. Except for deskwork, the EE from the SW was more correlated to the criterion EE than the EE from the RT3.

Conclusion: The results indicate that neither of the AMs is an appropriate tool for quantifying physical activity in MWUs with paraplegia. However, the accuracy of EE estimation could be potentially improved by building new regression models based on wheelchair-related activities.