Lower extremity kinematics and ground reaction forces after prophylactic lace-up ankle bracing

J Athl Train. 2008 May-Jun;43(3):234-41. doi: 10.4085/1062-6050-43.3.234.

Abstract

Context: Long-term effects of ankle bracing on lower extremity kinematics and kinetics are unknown. Ankle motion restriction may negatively affect the body's ability to attenuate ground reaction forces (GRFs).

Objective: To evaluate the immediate and long-term effects of ankle bracing on lower extremity kinematics and GRFs during a jump landing.

Design: Experimental mixed model (2 [group] x 2 [brace] x 2 [time]) with repeated measures.

Setting: Sports medicine research laboratory.

Patients or other participants: A total of 37 healthy subjects were assigned randomly to either the intervention (n = 11 men, 8 women; age = 19.63 +/- 0.72 years, height = 176.05 +/- 10.58 cm, mass = 71.50 +/- 13.15 kg) or control group (n = 11 men, 7 women; age = 19.94 +/- 1.44 years, height = 179.15 +/- 8.81 cm, mass = 74.10 +/- 10.33 kg).

Intervention(s): The intervention group wore braces on both ankles and the control group did not wear braces during all recreational activities for an 8-week period.

Main outcome measure(s): Initial ground contact angles, maximum joint angles, time to reach maximum joint angles, and joint range of motion for sagittal-plane knee and ankle motion were measured during a jump-landing task. Peak vertical GRF and the time to reach peak vertical GRF were assessed also.

Results: While participants were wearing the brace, ankle plantar flexion at initial ground contact (brace = 35 degrees +/- 13 degrees , no brace = 38 degrees +/- 15 degrees , P = .024), maximum dorsiflexion (brace = 21 degrees +/- 7 degrees , no brace = 22 degrees +/- 6 degrees , P = .04), dorsiflexion range of motion (brace = 56 degrees +/- 14 degrees , no brace = 59 degrees +/- 16 degrees , P = .001), and knee flexion range of motion (brace = 79 degrees +/- 16 degrees , no brace = 82 degrees +/- 16 degrees , P = .036) decreased, whereas knee flexion at initial ground contact increased (brace = 12 degrees +/- 9 degrees , no brace = 9 degrees +/- 9 degrees , P = .0001). Wearing the brace for 8 weeks did not affect any of the outcome measures, and the brace caused no changes in vertical GRFs (P > .05).

Conclusions: Although ankle sagittal-plane motion was restricted with the brace, knee flexion upon landing increased and peak vertical GRF did not change. The type of lace-up brace used in this study appeared to restrict ankle motion without increasing knee extension or vertical GRFs and without changing kinematics or kinetics over time.

Keywords: braces, external ankle supports; injury prevention; landings; prophylactic.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ankle Injuries / prevention & control*
  • Biomechanical Phenomena
  • Braces*
  • Female
  • Humans
  • Lower Extremity*
  • Male
  • Range of Motion, Articular
  • Sports Medicine
  • Time Factors