Clinical Study Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury

Objective. To study whether values for peak oxygen uptake (VO 2peak ) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO 2peak and peak power output (PO peak ) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO 2peak (mL⋅kg −1 ⋅min −1 ) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO 2-30W ) was significantly lower during WCE compared to ACE ( < 0.039). Mean (95% CI) PO peak (W) were 130 (111-138) and 100 (83-110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271

Neuromuscular performance of paretic versus non-paretic plantar flexors after stroke.

The objective of this study was to compare the neuromuscular function of the paretic and non-paretic plantar flexors (i.e. soleus, gastrocnemius medialis, lateralis) in chronic stroke patients. It was hypothesized that the contractile rate of force development (RFD) and neural activation, assessed by electromyogram (EMG) and V-waves normalized to the M-wave, and voluntary activation (twitch interpolation) would be reduced during plantar flexor maximum voluntary isometric contraction and that the evoked muscle twitch properties would be reduced in the paretic limb. Ten chronic stroke survivors completed the study. The main findings were that the paretic side showed deteriorated function compared to the non-paretic leg in terms of (1) RFD in all analyzed time windows from force onset to 250 ms, although relative RFD (i.e. normalized to maximum voluntary force) was similar; (2) fast neural activation (for most analyzed time windows), assessed by EMG activity in time windows from EMG onset to 250 ms; (3) V-wave responses (except for gastrocnemius medialis); (4) voluntary activation; (5) the evoked peak twitch force, although there was no evidence of intrinsic muscle slowing; (6) EMG activity obtained at maximal voluntary force. In conclusion, this study demonstrates considerable neuromuscular asymmetry of the plantar flexors in chronic stroke survivors. Effective rehabilitation regimes should be investigated

Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury

Objective. To study whether values for peak oxygen uptake (VO2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO2peak and peak power output (POpeak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO2peak (mL·kg−1·min−1) between ACE (27.3 +/- 3.2) and WCE (27.4 +/- 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO2-30W) was significantly lower during WCE compared to ACE (P peak (W) were 130 (111–138) and 100 (83–110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271

Oxygen uptake during functional activities after stroke-Reliability and validity of a portable ergospirometry system.

People with stroke have a low peak aerobic capacity and experience increased effort during performance of daily activities. The purpose of this study was to examine test-retest reliability of a portable ergospirometry system in people with stroke during performance of functional activities in a field-test. Secondary aims were to examine the proportion of oxygen consumed during the field-test in relation to the peak-test and to analyse the correlation between the oxygen uptake during the field-test and peak-test in order to support the validity of the field-test.With simultaneous measurement of oxygen consumption, participants performed a standardized field-test consisting of five activities; walking over ground, stair walking, stepping over obstacles, walking slalom between cones and from a standing position lifting objects from one height to another. All activities were performed in self-selected speed. Prior to the field-test, a peak aerobic capacity test was performed. The field-test was repeated minimum 2 and maximum 14 days between the tests. ICC2,1 and Bland Altman tests (Limits of Agreement, LoA) were used to analyse test-retest reliability.In total 31 participants (39% women, mean (SD) age 54.5 (12.7) years and 21.1 (14.3) months' post-stroke) were included. The ICC2,1 was ≥ 0.80 for absolute V̇O2, relative V̇O2, minute ventilation, CO2, respiratory exchange ratio, heart rate and Borgs rating of perceived exertion. ICC2,1 for total time to complete the field-test was 0.99. Mean difference in steady state V̇O2 during Test 1 and Test 2 was -0.40 (2.12) The LoAs were -3.75 and 4.51. Participants spent 60.7% of their V̇O2peak performing functional activities. Correlation between field-test and peak-test was 0.689, p = 0.001 for absolute and 0.733, p = 0.001 for relative V̇O2.This study presents first evidence on reliability of oxygen uptake during performance of functional activities after stroke, showing very good test-retest reliability. The secondary analysis showed that the amount of energy spent during the field-test relative to the peak-test was high and the correlation between the two test was good, supporting the validity of this method

Effect of lower extremity functional electrical stimulation pulsed isometric contractions on arm cycling peak oxygen uptake in spinal cord injured individuals

Objective - To compare peak oxygen uptake (VO2peak) between: (i) functional electrical stimulation lower extremity pulsed isometric muscle contractions combined with arm cycling (FES iso hybrid), (ii) functional electrical stimulation cycling combined with arm cycling (FES hybrid cycling), and (iii) arm cycling exercise (ACE) in individuals with spinal cord injury with level of injury above and below T6. Design - Cross-over repeated measures design. Methods/participants - Individuals with spinal cord injury (n = 15) with level of injury between C4 and T12, were divided into groups; above (spinal cord injury – high, n = 8) and below (spinal cord injury – low, n = 7) T6 level. On separate days, VO2peak was compared between: (i) ACE, (ii) FES iso hybrid, and (iii) FES hybrid cycling. Results - In the SCI–high group, FES iso hybrid increased VO2peak (17.6 (standard deviation (SD) 5.0) to 23.6 (SD 3.6) ml/kg/min; p = 0.001) and ventilation (50.4 (SD 20.8) to 58.2 (SD 20.7) l/min; p = 0.034) more than ACE. Furthermore, FES hybrid cycling resulted in a 6.8 ml/kg/min higher VO2peak (p = 0.001) and an 11.0 litres/minute (p = 0.001) higher ventilation. ACE peak workload was 10.5 W (p = 0.001) higher during FES hybrid cycling compared with ACE. In the spinal cord injury – low group, no significant differences were found between the modalities. Conclusion - VO2peak increased when ACE was combined with FES iso hybrid or FES hybrid cycling in persons with spinal cord injury above the T6 level. Portable FES may serve as a less resource-demanding alternative to stationary FES cycling, and may have important implications for exercise prescription for spinal cord injury

Effect of lower extremity functional electrical stimulation pulsed isometric contractions on arm cycling peak oxygen uptake in spinal cord injured individuals

Objective: To compare peak oxygen uptake (VO2peak) between: (i) functional electrical stimulation lower extremity pulsed isometric muscle contractions combined with arm cycling (FES iso hybrid), (ii) functional electrical stimulation cycling combined with arm cycling (FES hybrid cycling), and (iii) arm cycling exercise (ACE) in individuals with spinal cord injury with level of injury above and below T6. Design: Cross-over repeated measures design. Methods/participants: Individuals with spinal cord injury (n = 15) with level of injury between C4 and T12, were divided into groups; above (spinal cord injury – high, n = 8) and below (spinal cord injury – low, n = 7) T6 level. On separate days, VO2peak was compared between: (i) ACE, (ii) FES iso hybrid, and (iii) FES hybrid cycling. Results: In the SCI–high group, FES iso hybrid increased VO2peak (17.6 (standard deviation (SD) 5.0) to 23.6 (SD 3.6) ml/kg/min; p = 0.001) and ventilation (50.4 (SD 20.8) to 58.2 (SD 20.7) l/min; p = 0.034) more than ACE. Furthermore, FES hybrid cycling resulted in a 6.8 ml/kg/min higher VO2peak (p = 0.001) and an 11.0 litres/minute (p = 0.001) higher ventilation. ACE peak workload was 10.5 W (p = 0.001) higher during FES hybrid cycling compared with ACE. In the spinal cord injury – low group, no significant differences were found between the modalities. Conclusion: VO2peak increased when ACE was combined with FES iso hybrid or FES hybrid cycling in persons with spinal cord injury above the T6 level. Portable FES may serve as a less resource-demanding alternative to stationary FES cycling, and may have important implications for exercise prescription for spinal cord injury

Effect of lower extremity functional electrical stimulation pulsed isometric contractions on arm cycling peak oxygen uptake in spinal cord injured individuals

Objective: To compare peak oxygen uptake (VO2peak) between: (i) functional electrical stimulation lower extremity pulsed isometric muscle contractions combined with arm cycling (FES iso hybrid), (ii) functional electrical stimulation cycling combined with arm cycling (FES hybrid cycling), and (iii) arm cycling exercise (ACE) in individuals with spinal cord injury with level of injury above and below T6. Design: Cross-over repeated measures design. Methods/participants: Individuals with spinal cord injury (n = 15) with level of injury between C4 and T12, were divided into groups; above (spinal cord injury – high, n = 8) and below (spinal cord injury – low, n = 7) T6 level. On separate days, VO2peak was compared between: (i) ACE, (ii) FES iso hybrid, and (iii) FES hybrid cycling. Results: In the SCI–high group, FES iso hybrid increased VO2peak (17.6 (standard deviation (SD) 5.0) to 23.6 (SD 3.6) ml/kg/min; p = 0.001) and ventilation (50.4 (SD 20.8) to 58.2 (SD 20.7) l/min; p = 0.034) more than ACE. Furthermore, FES hybrid cycling resulted in a 6.8 ml/kg/min higher VO2peak (p = 0.001) and an 11.0 litres/minute (p = 0.001) higher ventilation. ACE peak workload was 10.5 W (p = 0.001) higher during FES hybrid cycling compared with ACE. In the spinal cord injury – low group, no significant differences were found between the modalities. Conclusion: VO2peak increased when ACE was combined with FES iso hybrid or FES hybrid cycling in persons with spinal cord injury above the T6 level. Portable FES may serve as a less resource-demanding alternative to stationary FES cycling, and may have important implications for exercise prescription for spinal cord injury

Bland-Altman plot of within subject change in VO₂ between Test 1 and Test 2 (mL/kg/min).

<p>Red horizontal line represents the mean difference between tests. Green horizontal lines are reference lines representing 5% and 95% confidence intervals (± 1.96 SD).</p

Reliability measures for the 6MWT (n = 31).

<p>Reliability measures for the 6MWT (n = 31).</p