title: Relationship Between Hand Contact Angle and Shoulder Loading During Manual Wheelchair Propulsion by Individuals with Paraplegia.
abstract: BACKGROUND
  Shoulder loading during manual wheelchair propulsion (WCP) contributes to the development of shoulder pain in individuals with spinal cord injury (SCI).
  
  
  OBJECTIVE
  To use regression analysis to investigate the relationships between the hand contact angle (location of the hand on the pushrim at initial contact and release during the push phase of the WCP cycle) with propulsion characteristics, pushrim forces, and shoulder kinetics during WCP in individuals with paraplegia.
  
  
  METHODS
  Biomechanical data were collected from 222 individuals (198 men and 24 women) with paraplegia from SCI during WCP on a stationary ergometer at a self-selected speed. The average age of participants was 34.7 years (±9.3), mean time since SCI was 9.3 years (±6.1), and average body weight was 74.4 kg (±15.9). The majority (n = 127; 56%) of participants had lower level paraplegia (T8 to L5) and 95 (42%) had high paraplegia (T2 to T7).
  
  
  RESULTS
  Increased push arc (mean = 75.3°) was associated with greater velocity (R = 0.384, P < .001) and cycle distance (R = 0.658, P < .001) and reduced cadence (R = -0.419, P <.001). Initial contact angle and hand release angles were equally associated with cycle distance and cadence, whereas a more anterior release angle was associated with greater velocity (R = 0.372, P < .001). When controlling for body weight, a more posterior initial contact angle was associated with greater posterior shoulder net joint force (R = 0.229, P = .001) and greater flexor net joint moment (R = 0.204, P = .002), whereas a more anterior hand release angle was significantly associated with increased vertical (R = 0.270, P < .001) and greater lateral (R = .293, P < .001) pushrim forces; greater shoulder net joint forces in all 3 planes - posterior (R = 0.164, P = .015), superior (R = 0.176, P = .009), and medial (R = 0.284, P < .001); and greater external rotator (R = 0.176, P = .009) and adductor (R = 0.259, P = .001) net joint moments.
  
  
  CONCLUSIONS
  Current clinical practice guidelines recommend using long, smooth strokes during manual WCP to reduce peak shoulder forces and to prevent shoulder pain development. The position of the hand at both initial contact and hand release must be considered in WCP training. It is recommended that participants should reach back to initiate contact with the pushrim to maximize push arc but avoid a more anterior hand position at release, because this could increase shoulder load during the push phase of WCP.
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.|Rehabilitation Engineering, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Philip Santos
authors.initials: PS
authors.lastname: Requejo
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Mulroy
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Puja
authors.initials: P
authors.lastname: Ruparel
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Hatchett
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Lisa Lighthall
authors.initials: LL
authors.lastname: Haubert
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Eberly
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, California.
authors.forename: JoAnne K
authors.initials: JK
authors.lastname: Gronley
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D016552:Ergometry; D005260:Female; D006225:Hand; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D009068:Movement; D009132:Muscles / Q000502:physiology*; D010264:Paraplegia / Q000209:etiology; D012782:Shoulder; D012785:Shoulder Joint; D020069:Shoulder Pain / Q000209:etiology / Q000517:prevention & control*; D013119:Spinal Cord Injuries / Q000150:complications; D014910:Wheelchairs; D055815:Young Adult
keywords: biomechanics; manual wheelchair propulsion; paraplegia; shoulder; spinal cord injury