Limits...
Trunk and shoulder kinematic and kinetic and electromyographic adaptations to slope increase during motorized treadmill propulsion among manual wheelchair users with a spinal cord injury.

Gagnon D, Babineau AC, Champagne A, Desroches G, Aissaoui R - Biomed Res Int (2015)

Bottom Line: To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions.Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper.The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

View Article: PubMed Central - PubMed

Affiliation: School of Rehabilitation, Université de Montréal, Montreal, QC, Canada H3C 3J7 ; Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Institut de Réadaptation Gingras-Lindsay-de-Montréal, 6300 Darlington, Montreal, QC, Canada H3S 2J4.

ABSTRACT
The main objective was to quantify the effects of five different slopes on trunk and shoulder kinematics as well as shoulder kinetic and muscular demands during manual wheelchair (MWC) propulsion on a motorized treadmill. Eighteen participants with spinal cord injury propelled their MWC at a self-selected constant speed on a motorized treadmill set at different slopes (0°, 2.7°, 3.6°, 4.8°, and 7.1°). Trunk and upper limb movements were recorded with a motion analysis system. Net shoulder joint moments were computed with the forces applied to the handrims measured with an instrumented wheel. To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions. Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper. The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

Show MeSH

Related in: MedlinePlus

Illustration of three slopes tested during motorized treadmill MWC propulsion: (a) 0° slope, (b) 3.6° slope, and (c) 7.1° slope.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4352451&req=5

fig1: Illustration of three slopes tested during motorized treadmill MWC propulsion: (a) 0° slope, (b) 3.6° slope, and (c) 7.1° slope.

Mentions: At the start of the laboratory assessment, each participant was given a five-minute familiarization period of motorized treadmill propulsion at various slopes that differed from those investigated in the present study during which rest periods were allowed to avoid fatigue. The motorized dual belt instrumented treadmill (Bertec Corporation, Columbus, Ohio, United States) (width = 0.84 m; length = 1.84 m) was adapted for safe MWC propulsion. The MWC was anchored with elastic bands to a bilateral frictionless gliding safety system preventing excessive antero-posterior and rotational movements of the MWC (Figure 1). The imposed speed of the treadmill was adjusted for each participant to mimic the self-selected natural propulsion speed measured during a timed performance-based 20 meter MWC propulsion test. This last test was performed three times with a two-minute rest taken between trials to compute the self-selected natural propulsion speed. Thereafter, each participant first propelled their own MWC on the motorized treadmill with a level ground (0°) and then randomly at four different slopes: 2.7°, 3.6°, 4.8°, and 7.1°, reflecting an increase from one unit of height to 20, 16, 12, and 8 units of length, respectively. For each angle tested, two trials lasting a maximum of one minute (i.e., 20 consecutive pushes) and separated by a two-minute rest period were recorded. During each trial, the last 10 complete consecutive propulsion cycles recorded were used to compute the measurements of interest (i.e., trunk and shoulder kinematics, shoulder kinetics, and shoulder muscular demand) and were essential to confirm the successful completion for each slope tested (i.e., two trials/slope). This study design was selected to minimize systematic errors related to the testing (e.g., learning) and temporary maturation effects (e.g., fatigue) associated with the experimental protocol and to conclude that the findings of the present study do not result from these potential threats to internal validity. Participants rated their perceived nondominant localized U/L effort using a 10 cm visual analog scale ranging from “no effort” (0 cm) to “maximum effort” (10 cm) during the rest periods.


Trunk and shoulder kinematic and kinetic and electromyographic adaptations to slope increase during motorized treadmill propulsion among manual wheelchair users with a spinal cord injury.

Gagnon D, Babineau AC, Champagne A, Desroches G, Aissaoui R - Biomed Res Int (2015)

Illustration of three slopes tested during motorized treadmill MWC propulsion: (a) 0° slope, (b) 3.6° slope, and (c) 7.1° slope.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4352451&req=5

fig1: Illustration of three slopes tested during motorized treadmill MWC propulsion: (a) 0° slope, (b) 3.6° slope, and (c) 7.1° slope.
Mentions: At the start of the laboratory assessment, each participant was given a five-minute familiarization period of motorized treadmill propulsion at various slopes that differed from those investigated in the present study during which rest periods were allowed to avoid fatigue. The motorized dual belt instrumented treadmill (Bertec Corporation, Columbus, Ohio, United States) (width = 0.84 m; length = 1.84 m) was adapted for safe MWC propulsion. The MWC was anchored with elastic bands to a bilateral frictionless gliding safety system preventing excessive antero-posterior and rotational movements of the MWC (Figure 1). The imposed speed of the treadmill was adjusted for each participant to mimic the self-selected natural propulsion speed measured during a timed performance-based 20 meter MWC propulsion test. This last test was performed three times with a two-minute rest taken between trials to compute the self-selected natural propulsion speed. Thereafter, each participant first propelled their own MWC on the motorized treadmill with a level ground (0°) and then randomly at four different slopes: 2.7°, 3.6°, 4.8°, and 7.1°, reflecting an increase from one unit of height to 20, 16, 12, and 8 units of length, respectively. For each angle tested, two trials lasting a maximum of one minute (i.e., 20 consecutive pushes) and separated by a two-minute rest period were recorded. During each trial, the last 10 complete consecutive propulsion cycles recorded were used to compute the measurements of interest (i.e., trunk and shoulder kinematics, shoulder kinetics, and shoulder muscular demand) and were essential to confirm the successful completion for each slope tested (i.e., two trials/slope). This study design was selected to minimize systematic errors related to the testing (e.g., learning) and temporary maturation effects (e.g., fatigue) associated with the experimental protocol and to conclude that the findings of the present study do not result from these potential threats to internal validity. Participants rated their perceived nondominant localized U/L effort using a 10 cm visual analog scale ranging from “no effort” (0 cm) to “maximum effort” (10 cm) during the rest periods.

Bottom Line: To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions.Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper.The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

View Article: PubMed Central - PubMed

Affiliation: School of Rehabilitation, Université de Montréal, Montreal, QC, Canada H3C 3J7 ; Pathokinesiology Laboratory, Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, Institut de Réadaptation Gingras-Lindsay-de-Montréal, 6300 Darlington, Montreal, QC, Canada H3S 2J4.

ABSTRACT
The main objective was to quantify the effects of five different slopes on trunk and shoulder kinematics as well as shoulder kinetic and muscular demands during manual wheelchair (MWC) propulsion on a motorized treadmill. Eighteen participants with spinal cord injury propelled their MWC at a self-selected constant speed on a motorized treadmill set at different slopes (0°, 2.7°, 3.6°, 4.8°, and 7.1°). Trunk and upper limb movements were recorded with a motion analysis system. Net shoulder joint moments were computed with the forces applied to the handrims measured with an instrumented wheel. To quantify muscular demand, the electromyographic activity (EMG) of the pectoralis major (clavicular and sternal portions) and deltoid (anterior and posterior fibers) was recorded during the experimental tasks and normalized against maximum EMG values obtained during static contractions. Overall, forward trunk flexion and shoulder flexion increased as the slope became steeper, whereas shoulder flexion, adduction, and internal rotation moments along with the muscular demand also increased as the slope became steeper. The results confirm that forward trunk flexion and shoulder flexion movement amplitudes, along with shoulder mechanical and muscular demands, generally increase when the slope of the treadmill increases despite some similarities between the 2.7° to 3.6° and 3.6° to 4.8° slope increments.

Show MeSH
Related in: MedlinePlus