Richard H. Robinson

Support for a Reduction in the Number of Trials Needed for the Star Excursion Balance Test

UNLABELLED Robinson RH, Gribble PA. Support for a reduction in the number of trials needed for the Star Excursion Balance Test. OBJECTIVE To determine the number of trials necessary to achieve stability in excursion distance and stance leg angular displacement for the 8 directions of the Star Excursion Balance Test (SEBT). DESIGN One-way repeated-measures analysis of variance. SETTING Athletic training laboratory. PARTICIPANTS Twenty participants (10 men, 10 women) without any known musculoskeletal injuries or neurologic deficits that could have negatively affected their dynamic balance volunteered for the study. INTERVENTION Participants completed 6 practice and 3 test trials in each of the 8 reach directions of the SEBT. MAIN OUTCOME MEASURES Excursion distances of the reaching leg normalized to leg length and angular displacement at the hip and knee of the stance leg in all 3 planes of movement were determined. RESULTS There were significant increases in excursion distance, hip flexion, and knee flexion for 7, 4, and 5 of the 8 reach directions, respectively. CONCLUSIONS For the majority of the reach directions, maximum excursion distances and stance leg angular displacement values achieved stability within the first 4 practice trials, thus justifying a reduction in the recommended number of practice trials from 6 to 4 and supporting the trend toward simplifying SEBT administration.

Alterations in Knee Kinematics and Dynamic Stability Associated With Chronic Ankle Instability

CONTEXT Chronic ankle instability (CAI) has been previously and separately associated with deficits in dynamic stability and proximal joint neuromuscular alterations, but how the 2 factors relate is unclear. OBJECTIVE To examine the contributions of lower extremity kinematics during an assessment of dynamic stability in participants with CAI. DESIGN Repeated-measures case-control design. SETTING Research laboratory. PATIENTS OR OTHER PARTICIPANTS Thirty-eight volunteers were categorized into groups of those with unilateral CAI (10 men, 9 women; age = 20.3 +/- 2.9 years, height = 1.77 +/- 0.1 m, mass = 76.19 +/- 13.19 kg) and those without (10 men, 9 women; age = 23.1 +/- 3.9 years, height = 1.72 +/- 0.1 m, mass = 72.67 +/- 16.0 kg). INTERVENTION(S) Participants performed 10 jump landings on each limb with a rest period between test limbs. MAIN OUTCOME MEASURE(S) Ankle plantar flexion, knee flexion, and hip flexion were captured with an electromagnetic tracking device at the point of ground impact. Ground reaction force data were used to calculate time to stabilization in the anteroposterior and mediolateral planes. RESULTS For the anteroposterior plane, we found a group-by-side interaction (P = .003), with the injured side of the CAI group demonstrating reduced dynamic stability. For knee flexion, a group main effect (P = .008) showed that the CAI group landed with less knee flexion than the control group. CONCLUSIONS Diminished dynamic stability and decreased knee flexion angle at initial contact were apparent in the CAI group and may play a role in contributing to CAI. This altered kinematic pattern may influence preventive and therapeutic interventions for those with CAI.

An Examination of Ankle, Knee, and Hip Torque Production in Individuals With Chronic Ankle Instability

Gribble, PA and Robinson, RH. An examination of ankle, knee, and hip torque production in individuals with chronic ankle instability. J Strength Cond Res 23(2): 395-400, 2009-There is some debate in the literature as to whether strength deficits exist at the ankle in individuals with chronic ankle instability (CAI). Additionally, there is evidence to suggest that knee and hip performance is altered in those with CAI. Therefore, the purpose of this study was to determine whether CAI is associated with deficits in ankle, knee, and hip torque. Fifteen subjects with unilateral CAI and fifteen subjects with healthy ankles participated. Subjects reported to the laboratory for one session during which the torque production of ankle plantar flexion/dorsiflexion, knee flexion/extension, and hip flexion/extension were measured with an isokinetic device. Subjects performed 5 maximum-effort repetitions of a concentric/concentric protocol at 60°·s−1 for both extremities. Average peak torque (APT) values were calculated. The subjects with CAI demonstrated significantly less APT production for knee flexion (F1,28 = 5.40; p = 0.03) and extension (F1,28 = 5.34; p = 0.03). Subjects with CAI exhibited significantly less APT for ankle plantar flexion in the injured limb compared with their noninjured limb (F1,28 = 6.51; p = 0.02). No significant difference in ankle dorsiflexion or hip flexion/extension APT production existed between the 2 groups. Individuals with CAI, in addition to deficits in ankle plantar flexion torque, had deficits in knee flexor and extensor torque, suggesting that distal joint instability may lead to knee joint neuromuscular adaptations. There were no similar deficits at the hip. Future research should determine what implications this has for prevention and rehabilitation of lower-extremity injury. Clinicians may need to consider including rehabilitation efforts to address these deficits when rehabilitating patients with CAI.