Quantifying cardiorespiratory responses resulting from speed and slope increments during motorized treadmill propulsion among manual wheelchair users

Relationship between rolling resistance, preferred speed, and manual wheelchair propulsion mechanics in non-disabled adults

PURPOSE

To characterize the relationship among rolling resistance (RR), preferred speed, and propulsion mechanics.

METHODS

N = 11 non-disabled individuals (mean (SD)); Age 24 years (2), BMI 23.8 kg/m2 (4.3) completed a submaximal graded wheelchair exercise test (GXTsubmax, fixed speed, terminated at Rating of Perceived Effort (RPE)=8 (0-10 scale)) and a single-blind, within-subject repeated measures wheelchair propulsion experiment (RME). RR at RPE = 10 (estimated maximum workload, Maxestimated) was estimated from the GXTsubmax RPE-RR relationship. RME consisted of N = 19 1-minute trials (self-selected speed) each followed by 2-minutes rest. The trials included N = 16 unique RR between 25-100% of Maxestimated. Averages of all pushes in N = 16 unique 1-minute trials were computed for average RR (N), speed (m/s), peak force (Fpeak (N)), force rate of rise (Fror (N/s)), push frequency (PF (pushes/min)), and push length (PL (deg)).

RESULTS

Repeated measures correlation assessed relationships among outcome variables (α = 0.05). RR was associated with decreased speed (r=-0.81, p < 0.001), increased Fpeak (r = 0.92), Fror (r = 0.26), and PL (r = 0.32) (all p > 0.001), and unrelated to PF (r = 0.02, p = 0.848). Increased speed was associated with increased Fror (r = 0.23, p = 0.003) and PF (r = 0.27, p < 0.001) and decreased Fpeak (r=-0.66, p < 0.001) and PL (r=-0.25, p < 0.001).

CONCLUSION

Increasing RR increases Fpeak despite reducing self-selected speed. RR and speed were strongly and moderately related to Fpeak, respectively, but weakly related to other propulsion mechanics. These results suggest that reducing user-system RR may confer dual benefits of improved mobility and decreased upper extremity loading. Further testing among wheelchair users is required. Clinical trial registration number: NCT04987177.

Accuracy and Precision of Actigraphy and SMARTwheels for Measuring Push Counts Across a Series of Wheelchair Propulsion Trials in Non-disabled Young Adults

Background: There has been a growing interest in “Lifestyle Physical Activity” (LPA) among wheelchair users. LPA can be quantified via “pushes” as an outcome metric. This study examined the accuracy and precision of research-grade devices for counting pushes across a series of wheelchair propulsion trials. Methods: Eleven non-disabled, young adults completed 19, 1-minute wheelchair propulsion trials at self-selected speeds with a wheelchair equipped with a SMARTwheel (SW) device while being video recorded. Participants also wore 2 ActiGraph accelerometers, one on the wrist and one on the upper arm. Video footage enabled manual counting of the number of pushes (gold standard). Total pushes were averaged across 16 workloads (3 trials of repeated workloads were excluded) for each device and compared to manually counted pushes. Results: Compared to manually counted pushes, SW demonstrated the greatest accuracy (mean difference [MD] compared to video of 2.3 pushes [4.5% error]) and precision (standard deviation of the mean difference [SDMD]) compared to video of 4 pushes, (Coefficient of Variation [CV] =.04), followed by the upper arm-worn accelerometer (MD of 4.4 pushes [10.4% error] and SDMD of 10, [CV= .06]) and the wrist-worn accelerometer (MD of 12.6 pushes [27.8% error] and SDMD of 13 [CV=.15]). Conclusions: SW demonstrated greater accuracy and precision than ActiGraph accelerometers placed on the upper arm and wrist. The accelerometer placed on the upper arm was more accurate and precise than the accelerometer placed on the wrist. Future investigations should be conducted to identify the source(s) of inaccuracy among wearable push counters.

Test-Retest Reliability of Physiological Variables During Submaximal Seated Upper-Body Poling in Able-Bodied Participants

Purpose: To investigate the test–retest reliability of physiological variables across four different test days and four different submaximal exercise intensities during seated upper-body poling (UBP).

Methods: Thirteen abled-bodied, upper-body trained men (age 29±3years; body mass 84±12kg; height 183±5cm) performed four submaximal 4-min stages of seated UBP on four separate test days. The four submaximal stages were set at individual power outputs corresponding to a rating of perceived exertion of 9, 11, 13, and 15. The absolute reliability for pairwise test-day comparisons of the physiological variables was investigated with the smallest detectable change percentage (%SDC) and the relative reliability with the interclass correlation coefficient (ICC).

Results: Absolute and relative reliability across test-day comparisons and submaximal stages were moderate to excellent for all variables investigated (V̇O₂ – %SDC range: 5–13%, ICC range: 0.93–0.99; HR – %SDC range: 6–9%, ICC range: 0.91–0.97) other than blood lactate, for which absolute reliability was poor and relative reliability highly variable (%SDC range: 26–69%, ICC range: 0.44–0.92). Furthermore, absolute and relative reliability were consistent across the low-to-moderate exercise intensity spectrum and across test days.

Conclusion: Absolute and relative test–retest reliability were acceptable for all investigated physiological variables but blood lactate. The consistent test–retest reliability across the exercise intensity spectrum and across test days indicates that a familiarization period to the specific exercise modality may not be necessary. For generalizability, these findings need to be confirmed in athletes with a disability by future large-scale studies.

Changes to Biceps and Supraspinatus Tendons in Response to a Progressive Maximal Treadmill-Based Propulsion Aerobic Fitness Test in Manual Wheelchair Users: A Quantitative Musculoskeletal Ultrasound Study

Objective

To investigate if the completion of a recently developed treadmill-based wheelchair propulsion maximal progressive workload incremental test alters the integrity of the long head of the biceps and supraspinatus tendons using musculoskeletal ultrasound imaging biomarkers.

Method

Fifteen manual wheelchair users completed the incremental test. Ultrasound images of the long head of the biceps and supraspinatus tendons were recorded before, immediately after, and 48 hours after the completion of the test using a standardized protocol. Geometric, composition, and texture-related ultrasound biomarkers characterized tendon integrity.

Results

Participants propelled during 10.2 ± 2.9 minutes with the majority (N = 13/15) having reached at least the eighth stage of the test (speed = 0.8 m/s; slope = 3.6°). All ultrasound biomarkers characterizing tendon integrity, measured in the longitudinal and transversal planes for both tendons, were similar (p = 0.063 to 1.000) across measurement times.

Conclusion

The performance of the motorized treadmill wheelchair propulsion test to assess aerobic fitness produced no changes to ultrasound biomarkers of the biceps or supraspinatus tendons. Hence, there was no ultrasound imaging evidence of a maladaptive response due to overstimulation in these tendons immediately after and 48 hours after the performance of the test.

Effects of different increments in workload and duration on peak physiological responses during seated upper-body poling

PURPOSE

To compare the effects of test protocols with different increments in workload and duration on peak oxygen uptake ([Formula: see text]O_2peak), and related physiological parameters during seated upper-body poling (UBP).

METHODS

Thirteen upper-body trained, male individuals completed four UBP test protocols with increments in workload until volitional exhaustion in a counterbalanced order: 20 W increase/every 30 s, 20 W/60 s, 10 W/30 s and 10 W/60 s. Cardio-respiratory parameters and power output were measured throughout the duration of each test. Peak blood lactate concentration (bLa_peak) was measured after each test.

RESULTS

The mixed model analysis revealed no overall effect of test protocol on [Formula: see text]O_2peak, peak minute ventilation (VE_peak), peak heart rate (HR_peak), bLa_peak (all p ≥ 0.350), whereas an overall effect of test protocol was found on peak power output (PO_peak) (p = 0.0001), respiratory exchange ratio (RER) (p = 0.024) and test duration (p < 0.001). There was no difference in PO_peak between the 20 W/60 s (175 ± 25 W) and 10 W/30 s test (169 ± 27 W; p = 0.092), whereas PO_peak was lower in the 10 W/60 s test (152 ± 21 W) and higher in the 20 W/30 s test (189 ± 30 W) compared to the other tests (all p = 0.001). In addition, RER was 9.9% higher in the 20 W/30 s compared to the 10 W/60 s test protocol (p = 0.003).

CONCLUSIONS

The UBP test protocols with different increments in workload and duration did not influence [Formula: see text]O_2peak, and can therefore be used interchangeably when [Formula: see text]O_2peak is the primary outcome. However, PO_peak and RER depend upon the test protocol applied and the UBP test protocols can, therefore, not be used interchangeably when the latter is the primary outcome parameter.

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.

Reliability and minimal detectable change of a new treadmill-based progressive workload incremental test to measure cardiorespiratory fitness in manual wheelchair users

BACKGROUND

Cardiorespiratory fitness training is commonly provided to manual wheelchair users (MWUs) in rehabilitation and physical activity programs, emphasizing the need for a reliable task-specific incremental wheelchair propulsion test.

OBJECTIVE

Quantifying test-retest reliability and minimal detectable change (MDC) of key cardiorespiratory fitness measures following performance of a newly developed continuous treadmill-based wheelchair propulsion test (WPT_Treadmill).

METHODS

Twenty-five MWUs completed the WPT_Treadmill on two separate occasions within one week. During these tests, participants continuously propelled their wheelchair on a motorized treadmill while the exercise intensity was gradually increased every minute until exhaustion by changing the slope and/or speed according to a standardized protocol. Peak oxygen consumption (VO_2peak), carbon dioxide production (VCO_2peak), respiratory exchange ratio (RER_peak), minute ventilation (VE_peak) and heart rate (HR_peak) were computed. Time to exhaustion (TTE) and number of increments completed were also measured. Intra-class correlation coefficients (ICC) were calculated to determine test-retest reliability. Standard error of measurement (SEM) and MDC_90% values were calculated.

RESULTS

Excellent test-retest reliability was reached for almost all outcome measures (ICC=0.91-0.76), except for RER_peak (ICC=0.58), which reached good reliability. TTE (ICC=0.89) and number of increments (ICC=0.91) also reached excellent test-retest reliability. For the main outcome measures (VO_2peak and TTE), absolute SEM was 2.27 mL/kg/min and 0.76 minutes, respectively and absolute MDC_90% was 5.30 mL/kg/min and 1.77 minutes, respectively.

CONCLUSION

The WPT_Treadmill is a reliable test to assess cardiorespiratory fitness among MWUs. TTE and number of increments could be used as reliable outcome measures when VO₂ measurement is not possible.