Ice-induced anesthesia is often used to permit pain-free activity. However, icing before a skilled performance may distort the ability to acknowledge sensory stimuli and may thereby mask certain protective mechanisms. Inadequate peripheral feedback regarding position of a limb in space could expose the joint to injury. This study was designed to determine the effect of ice immersion on ankle joint position sense. Three different pretest conditions of no ice immersion, 5 min of ice immersion, and 20 min of ice immersion were administered to 31 subjects prior to joint angle replication testing with an electrogoniometer. Subjects completed eight repositioning trials (four at each of two test angles) following each condition. An analysis of variance (ANOVA) revealed no statistically significant difference between conditions, trials, or angles. The results suggest that joint position receptors in the ankle are resilient to this type of ice treatment, or that the affected receptors (i.e., skin and muscle) were adequately compensated for by other sensors such as joint receptors.
Jane LaRiviere and Louis R. Osternig
James C. Radcliffe and Louis R. Osternig
Seventy subjects were tested for (a) percent body weight controlled (lowered and raised) by the lower extremities via parallel squat exercise, (b) maximum vertical jump-reach, and (c) maximal depth jump-reach from six heights ranging from 0.30 to 1.05 m. The results suggest that maximum parallel squat performance represents a small proportion (8%) of the variance contributing to controlling increasing depth jump heights and that specific improvement in jumping performance may be achieved by relatively small amplitude prestretch movements rather than large depth jump heights. The implications of the present findings for the use of depth jumping in conditioning and rehabilitative protocols are that (a) extreme care must be exercised in selecting jump heights, as there is considerable variability in individual tolerance to a given height, and (b) depth jumping should be contraindicated in cases where high impulse loads can disrupt healing tissue and, if it is used in postinjury situations, should be reserved for the end phase of rehabilitation.
Rod A. Harter, Louis R. Osternig and Kenneth M. Singer
This study evaluated knee joint position sense in the ACL-reconstructed and contralateral normal knees of 48 male and female subjects (M age 27.6 ± 6.9 yrs). Subjects were blindfolded and tested on their ability to actively reproduce five passively placed knee positions at 5° intervals between 35 and 15° of knee flexion. Mean algebraic target angle error and mean absolute error values were measured in degrees. The grand mean absolute error for the postsurgical knees at all positions was 5.4 ± 3.2°, compared with 5.2 ± 2.7° for the normal contralateral knees. There were no significant differences in knee joint position sense between the postsurgical and normal contralateral limbs at any of the five positions tested. Pivot shift, anterolateral rotatory instability, and Lachman test results were poorly correlated with knee joint position sense. The results suggest that if knee joint position sense was indeed disrupted by ACL injury and reconstructive surgery, related sensory mechanisms compensated for any proprioceptive loss prior to the minimum 2-yr postsurgical follow-up period employed in our study.
James J. Hannigan, Louis R. Osternig and Li-Shan Chou
Weak hip muscle strength and excessive hip motion during running have been suggested as potential risk factors for developing patellofemoral pain syndrome (PFPS) in females, but not males. There is conflicting evidence on the relationship between hip strength and hip kinematics, which may be partly due to sex differences in the relationship between these parameters. Hip, pelvis, and trunk kinematics were collected while 60 healthy, habitual runners (23 females, 37 males) ran overground, and isometric hip abduction and external rotation strengths were measured bilaterally. Pearson correlation coefficients quantified sex-specific correlations between hip strength and kinematics, and unpaired t tests assessed sex differences in hip strength and kinematics. Hip abduction strength was moderately and inversely correlated to hip adduction excursion in females, and pelvic internal rotation excursion in males. Hip external rotation strength was moderately and inversely correlated to trunk flexion excursion in females. Finally, females displayed less hip external rotation strength and greater excursion at the hip and trunk during running compared to males. Despite the significant correlations, the relatively low r 2 values suggest that additional factors outside of strength contribute to a substantial portion of the variance in trunk, pelvis, and hip kinematics.