Comparison of Shoulder Muscle Activity During Reverse and Conventional Manual Wheelchair Propulsion in Persons with Paraplegia

Lisa Lighthall Haubert, Philip Requejo, Sara Mulroy, Somboon Maneekobkunwong, Diego Rodriguez and JoAnne Gronley
Pathokinesiology Lab, Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA

The RW with alternative rear wheel technology, allows forward propulsion by pulling back on the rim using larger posterior shoulder muscles vs. traditional push-phase muscles. This may substantially protect the subacromial structures from impingement to prevent injury and pain and preserve mobility, independence, and participation for individuals living with paraplegia. The significant reduction in infraspinatus activity suggests a reduction in the superior (impinging) force.
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Comparison of Temporal Spatial Characteristics and Shoulder Kinematics and Kinetics During Reverse and Conventional Manual Wheelchair Propulsion in Persons with Paraplegia

Lisa Lighthall Haubert, Philip Requejo, Sara Mulroy, Somboon Maneekobkunwong,Diego Rodriguez and JoAnne Gronley
Pathokinesiology Lab, Rancho Los Amigos National Rehabilitation Center, Downey, CA, USA

These results demonstrate that reverse propulsion requires an upward force applied to the pushrim which, combined with the weight of the arm, translates to a distraction force at the shoulder. In contrast, forward propulsion incorporates a downward pushrim force leading to a superior, potentially impinging shoulder joint force. Moreover, the overall demands on shoulder muscle groups are lower during the contact phase of pulling compared to forward pushing. Reverse propulsion may protect the subacromial structures and thereby prevent injury and pain and preserve mobility, independence, and participation for individuals living with paraplegia.
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Electromyographic Activities of Shoulder Muscles during Forward and Reverse Manual Wheelchair Propulsion

Diana Rincon, Shusheng Ye, Manuel Rodriguez, Salim Nasser
Biomechanics Laboratory, Department of Mechanical and Material Engineering,
FloridaInternational University, Miami, FL

Eight out of nine muscles were active during the propulsion phase in RWP, indicating that the technique is highly efficient as most of the muscle work is translated into propulsion work. On the other hand, high muscle activities during the recovery phase in FWP suggest that the process is wasteful and unstable. The triceps remained highly active during the propulsion phase in RWP (up to 50% into the propulsion cycle).

Both posterior and middle deltoids are highly active during RWP. The posterior deltoid is seen to provide propulsion torque, while middle deltoid activity corresponds to humerus abduction (upward movement of the humerus to the side) as the hand crossed the TDC of the wheel. M. deltoid contraction provided for both useful propulsion work, as well as maintaining shoulder stability (Ozkaya et al. 1999)

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Physiologic Comparison of Forward and Reverse Wheelchair Propulsion

Frank J. Salvi, MD, Martin D. Hoffman, AID, Sunil Sabharwal, MD, Philip S. Clifford, PhD. Archives of Physical Med Rehab 1998;79:36-40.

…Strike rates were significantly higher (p = .04) for forward wheeling than reverse wheeling (fig 6). There was a significant main effect increase (p = .003) in strike rate with increasing power outputs. A significant (p = .01) interaction effect between wheeling technique and power output indicates that there was a greater increase in strike rate across power outputs for forward wheeling than reverse wheeling.
…Finally, reverse wheeling might reduce the morbidity from overuse syndromes that develop from conventional forward wheelchair propulsion and might also serve as a tool for increasing

the function of what might otherwise be relatively underused muscles.

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Upper Body Posture Comparison between Reverse and Conventional Manual Wheelchair Propulsion

Diana Rincon, Shusheng Ye, Manuel Rodriguez, Salim Nasser
Biomechanics Laboratory, Department of Mechanical and Material Engineering,
Florida International University, Miami , FL

The RWP technique requires leaning of the torso to lesser degree when compared to FWP. Further, kyphosis is decreased when using RWP, which translates into an overall improved seating posture that provides the body with stability and can avoid harmful stresses. Slouching alters the biomechanics of the shoulder joint and can predispose the shoulder joint to impingement or dislocation problems. For wheelchair users, proper posture may be already compromised, but the benefits of a better posture are still unquestionable in the short and long term.

…Longer propulsion phases and cycle time also meant that stresses on the shoulder would be spread out over longer periods, thus reducing the effect of repeated impact as the hands strikes the hand rim.

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A Physiological Comparison of Forward vs Reverse Wheelchair Ergometry

ARIEL L. LINDEN, GEORGE J. HOLLAND, STEVEN F. LOY, and WILLIAM J. VINCENT
Exercise Physiology Laboratory, Department of Kinesiology
California State University, Northridge, CA 91330

…The reverse propulsion technique requires primary involvement of the large back muscles (shoulder extensors, spinal erectors etc.), as well as different limb and trunk movements.
In contrast, FOR propulsion relies predominately on the relatively small muscle groups of the chest and anterior shoulder (3,15).
…The nature of REV propulsion permits an application of force to the handrims over a longer distance, thereby enabling the individual to strike at the rims less frequently. This is evidenced by the significantly lower SPM for the REV, while maintaining the same RPM as the FOR mode (Fig. 3). In contrast, force application during the FOR exercise occurs in shorter “punching” motions, compelling the subject to strike at the hand-rims more times per minute in order to maintain a given PO level (2,13)
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