Search Results

You are looking at 1 - 7 of 7 items for

  • Author: James W. Youdas x
Clear All Modify Search
Restricted access

James W. Youdas, Erica F. Loder, Jody L. Moldenhauer, Christine R. Paulsen and John H. Hollman

Context:

Hip-abductor weakness is associated with many lower extremity injuries. A simple procedure to assess hip-abductor performance is necessary in patient populations.

Objective:

To describe the change in pelvic-on-femoral position of the stance limb before and after 45 seconds of resisted sidestepping.

Design:

Cross-sectional comparative.

Setting:

Laboratory.

Participants:

24 healthy women (24.6 ± 3.5 years) and 14 healthy men (24.5 ± 3.0 years).

Main Outcome Measures:

Pelvic-on-femoral position in degrees in single-leg stance before and after 45 seconds of resisted sidestepping.

Results:

The difference between the baseline and postexercise measurements for both men and women was significant (P < .05). The effect of the resisted-sidestepping exercise on the hip abductors was not statistically different between men and women.

Conclusions:

Forty-five seconds of resisted sidestepping using an elastic band produced a change in pelvic-on-femoral position in healthy adults. This test might be useful to detect impaired performance in hip abductors of patients with injury elsewhere in the musculoskeletal system.

Restricted access

James W. Youdas, Sara T. Mraz, Barbara J. Norstad, Jennifer J. Schinke and John H. Hollman

Context:

Hip abductor muscle weakness is related to many lower extremity injuries. A simple procedure, the Trendelenburg test, may be used to assess hip abductor performance in patient populations.

Objective:

To describe the minimal detectable change (MDC) in pelvic-on-femoral (P-O-F) position of the stance limb during the Trendelenburg test.

Setting:

Laboratory.

Participants:

45 healthy women (28 ± 8 years) and 45 healthy men (33 ± 11 years).

Main Outcome Measures:

P-O-F position in degrees in single-leg stance. Results: Baseline P-O-F position (hip adduction) was 83° ± 3° with a range from 76° to 94°. The intratester reliability (ICC3,1 for measurement of P-O-F position using a universal goniometer was 0.58 with a standard error of measurement (SEM) of 2°. The minimal detectable change (MDC) was calculated to be 4°.

Conclusions:

If a person’s P-O-F position changes less than 4° between measurements, then the P-O-F position is within measurement error and it can be determined that there has been no change in the performance of the hip abductor muscles when examined by the Trendelenburg test.

Restricted access

James W. Youdas, Timothy J. McLean, David A. Krause and John H. Hollman

Context:

Posterior calf stretching is believed to improve active ankle dorsiflexion range of motion (AADFROM) after acute ankle-inversion sprain.

Objective:

To describe AADFROM at baseline (postinjury) and at 2-wk time periods for 6 wk after acute inversion sprain.

Design:

Randomized trial.

Setting:

Sports clinic.

Participants:

11 men and 11 women (age range 11–54 y) with acute inversion sprain.

Intervention:

Standardized home exercise program for acute inversion sprain.

Main Outcome Measure:

AADFROM with the knee extended.

Results:

Time main effect on AADFROM was significant (F 3,57 = 108, P < .001). At baseline, mean active sagittal-plane motion of the ankle was 6° of plantar flexion, whereas at 2, 4, and 6 wk AADFROM was 7°, 11°, and 11°, respectively.

Conclusions:

AADFROM increased significantly from baseline to week 2 and from week 2 to week 4. Normal AADFROM was restored within 4 wk after acute inversion sprain.

Restricted access

James W. Youdas, Hannah E. Baartman, Brian J. Gahlon, Tyler J. Kohnen, Robert J. Sparling and John H. Hollman

Context: Suspension training devices use body weight resistance and unstable support surfaces that may facilitate muscle recruitment during push-up exercises. Objective: The authors examined muscle recruitment with surface electromyography on 4 shoulder and 4 torso muscles during (1) standard push-ups, (2) feet-suspended push-ups, (3) hands-suspended push-ups, and (4) dual-instability push-ups in which feet were suspended and hands were on unstable surfaces. Design: Cross-sectional design with repeated measures. Setting: Biomechanics laboratory. Participants: Thirty-two healthy men and women (mean age, 24.3 y; mean body mass index, 24.6 kg·m−2) participated. Intervention: Participants were tested while performing 2 repetitions each of 4 variations of push-ups. Main Outcome Measures: Muscle recruitment, normalized to maximum voluntary isometric contraction, was measured in 4 prime movers (anterior deltoid, pectoralis major, serratus anterior, and triceps brachii) and 4 torso stabilizers (external oblique, internal oblique, rectus abdominis, and upper erector spinae). Results: Muscle recruitment in the anterior deltoid, pectoralis major, and serratus anterior during suspended exercises was no greater than during standard push-ups. In contrast, torso stabilizer recruitment was significantly greater in the external oblique, internal oblique, and rectus abdominis during all 3 suspended exercises compared with standard push-ups. Suspended exercises under a dual-instability condition did not generate greater levels of muscle activation compared with conditions of single instability. Conclusions: Push-ups performed with suspension training systems may provide benefit if one’s goal is to enhance torso muscle training. One unstable surface may be sufficiently challenging for the client or athlete when performing push-up exercises with a suspension training device.

Restricted access

James W. Youdas, Kady E. Adams, John E. Bertucci, Koel J. Brooks, Meghan M. Nelson and John H. Hollman

Context:

No published studies have compared muscle activation levels simultaneously for the gluteus maximus and medius muscles of stance and moving limbs during standing hip-joint strengthening while using elastic-tubing resistance.

Objective:

To quantify activation levels bilaterally of the gluteus maximus and medius during resisted lower-extremity standing exercises using elastic tubing for the cross-over, reverse cross-over, front-pull, and back-pull exercise conditions.

Design:

Repeated measures.

Setting:

Laboratory.

Participants:

26 active and healthy people, 13 men (25 ± 3 y) and 13 women (24 ± 1 y).

Intervention:

Subjects completed 3 consecutive repetitions of lower-extremity exercises in random order.

Main Outcome Measures:

Surface electromyographic (EMG) signals were normalized to peak activity in the maximum voluntary isometric contraction (MVIC) trial and expressed as a percentage. Magnitudes of EMG recruitment were analyzed with a 2 × 4 repeated-measures ANOVA for each muscle (α = .05).

Results:

For the gluteus maximus an interaction between exercise and limb factor was significant (F 3,75 = 21.5; P < .001). The moving-limb gluteus maximus was activated more than the stance limb's during the back-pull exercise (P < .001), and moving-limb gluteus maximus muscle recruitment was greater for the back-pull exercise than for the cross-over, reverse cross-over, and front-pull exercises (P < .001). For the gluteus medius an interaction between exercise and limb factor was significant (F 3,75 = 3.7; P < .03). Gluteus medius muscle recruitment (% MVIC) was greater in the stance limb than moving limb when performing the front-pull exercise (P < .001). Moving-limb gluteus medius muscle recruitment was greater for the reverse cross-over exercise than for the cross-over, front-pull, and back-pull exercises (P < .001).

Conclusions:

From a clinical standpoint there is no therapeutic benefit to selectively activate the gluteus maximus and gluteus medius muscles on the stance limb by resisting sagittal- and frontal-plane hip movements on the moving limb using resistance supplied by elastic tubing.

Restricted access

John H. Hollman, Tyler A. Berling, Ellen O. Crum, Kelsie M. Miller, Brent T. Simmons and James W. Youdas

Context: Hip extension with hamstring-dominant rather than gluteus maximus-dominant recruitment may increase anterior femoracetabular forces and contribute to conditions that cause hip pain. Cueing methods during hip extension exercises may facilitate greater gluteus maximus recruitment. Objective: We examined whether specific verbal and tactile cues facilitate gluteus maximus recruitment while inhibiting hamstring recruitment during a bridging exercise. Design: Randomized controlled trial. Setting: Biomechanics laboratory. Participants: 30 young adult women (age 24 [3] y; BMI 22.2 [2.4] kg/m2). Intervention: Participants were tested over 2 sessions, 1 week apart, while performing 5 repetitions of a bridging exercise. At their second visit, participants in the experimental group received verbal and tactile cues intended to facilitate gluteus maximus recruitment and inhibit hamstring recruitment. Control group participants received no additional cues beyond original instructions. Main Outcome Measures: Gluteus maximus and hamstring recruitment were measured with surface electromyography, normalized to maximal voluntary isometric contractions (MVICs). Results: Gluteus maximus recruitment was unchanged in the control group and increased from 16.8 to 33.0% MVIC in the cueing group (F = 33.369, P < .001). Hamstring recruitment was unchanged in the control group but also increased from 16.5 to 29.8% MVIC in the cueing group (F = 6.400, P = .02). The effect size of the change in gluteus maximus recruitment in the cueing group (Cohen’s d = 1.5, 95% CI = 0.9 to 2.2) was not significantly greater than the effect size in hamstring recruitment (Cohen’s d = 0.8, 95% CI = 0.1 to 1.5). Conclusions: Verbal and tactile cues hypothesized to facilitate gluteus maximus recruitment yielded comparable increases in both gluteus maximus and hamstring recruitment. If one intends to promote hip extension by facilitating gluteus maximus recruitment while inhibiting hamstring recruitment during bridging exercises, the cueing methods employed in this study may not produce desired effects.

Restricted access

John H. Hollman, Barbara E. Ginos, Jakub Kozuchowski, Amanda S. Vaughn, David A. Krause and James W. Youdas

Context:

Reduced strength and activation of hip muscles might correlate with increased weight-bearing knee valgus.

Objective:

To describe relationships among frontal-plane hip and knee angles, hip-muscle strength, and electromyographic (EMG) recruitment in women during a step-down.

Design:

Exploratory study.

Setting:

Laboratory.

Participants:

20 healthy women 20 to 30 years of age.

Interventions:

Frontal-plane hip and knee angles were measured. Gluteus maximus and medius recruitment were examined with surface EMG. Hip-abduction and -external-rotation strength were quantified with handheld dynamometry.

Main Outcome Measurements:

The authors analyzed correlation coefficients between knee and hip angles, gluteus maximus and medius EMG, and hip-abduction and -external-rotation strength.

Results:

Hip-adduction angles (r = .755, P = .001), gluteus maximus EMG (r = −.451, P = .026), and hip-abduction strength (r = .455, P = .022) correlated with frontal-plane projections of knee valgus.

Conclusions:

Gluteus maximus recruitment might have greater association with reduced knee valgus in women than does external-rotation strength during step-down tasks. Gluteus medius strength might be associated with increased knee valgus.