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  • Author: Craig R. Denegar x
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Craig R. Denegar, Andrew P. Yoho, Alex J. Borowicz and Nancy Bifulco

The efficacy of low-volt, microamperage stimulation (LVMAS) in the treatment of wounds and fractures has been demonstrated. Although these devices are also commonly used to treat musculoskeletal conditions, the efficacy of this practice has not been demonstrated. In this study, delayed onset muscle soreness (DOMS) served as a model for musculoskeletal injury to compare daily treatment with LVMAS and static stretching to a placebo treatment and static stretching. DOMS was induced in the elbow flexor muscle group in 16 subjects, who were evaluated for pain, elbow flexor muscle group strength, and elbow extension range of motion. These data were collected before the eccentric exercise bout, before and after treatment 24, 48, 72, and 96 hours following the exercise bout, and again 196 hours after the exercise bout. No significant differences were found between LVMAS and placebo treatments on any of the variables across the duration of the study, but the LVMAS did provide a transient analgesic effect 24 and 48 hours following the eccentric exercise.

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Alan Peppard and Craig R. Denegar

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Jay Hertel, Craig R. Denegar, Phil D. Johnson, Sheri A. Hale and W.E. Buckley

Two studies were performed to estimate the reliability of the Cybex Reactor in assessing agility tasks. In Study 1, participants (n =13) underwent identical testing sessions twice in 1 week. In Study 2, participants (n = 13) underwent identical testing sessions twice in 1 week, once 3 weeks later, and once 6 weeks later. Testing sessions consisted of four identical agility tasks requiring participants to react to cues shown on a video monitor. In Study 1, intraclass correlation coefficients (ICC) were .47 for Day 1 and .75 for Day 2 for time to complete each task. Participants performed faster on Day 2 (p < .05). In Study 2, ICC ranged from .58 to .83. ICC between sessions ranged from .59 to .73. Participants performed significantly faster each successive session except between Weeks 3 and 6 (p < .05). The Reactor appears to be reliable in assessing agility tasks with test–retest intervals of up to 6 weeks.

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Craig R. Denegar and Alan Peppard

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Jay Hertel, Craig R. Denegar, W.E. Buckley, Neil A. Sharkey and Wayne L. Stokes

Objective:

To identify changes in sagittal- and frontal-plane center of pressure (COP) excursion length and velocity during single-leg stance under 6 orthotic conditions.

Design:

1 × 6 repeated-measures.

Setting:

University biomechanics laboratory.

Participants:

Fifteen healthy young adults without excessive forefoot, arch, or rear-foot malalignments.

Measurements:

Selected variables of COP length and velocity were calculated in both the frontal and sagittal planes during three 5-second trials of quiet unilateral stance.

Methods:

Postural control was assessed under 6 conditions: shoe only and 5 orthotics.

Results:

The medially posted orthotic caused the least frontal COP length and velocity, and the Cramer Sprained Ankle Orthotic® caused the greatest frontal-plane sway. No significant differences were found between the different orthotic conditions in sagittal-plane measures.

Conclusions:

Differently posted rear-foot orthotics had various effects on frontal-plane postural control in healthy participants. Further research is needed on pathological populations.

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Phillip A. Gribble, Richard H. Robinson, Jay Hertel and Craig R. Denegar

Context:

Deficits in static postural control related to fatigue have been investigated previously, but there is little evidence to link fatigue to performance measures of dynamic postural control.

Objective:

To investigate the effects of fatigue and gender on performance measures of the Star Excursion Balance Test (SEBT).

Design:

Mixed-model design.

Setting:

Research laboratory.

Participants:

16 healthy young adults.

Intervention:

Subjects performed the SEBT before and after 4 different fatiguing conditions.

Main Outcome Measures:

The normalized reach distances and sagittal-plane kinematics of the knee and hip were recorded.

Results:

Fatigue produced deficits in normalized reach distances and decreased knee flexion in all 3 reaching directions. Overall, women were able to reach farther than men while simultaneously demonstrating a greater amount of knee flexion.

Conclusions:

Gender differences were observed during performance of the SEBT, with women demonstrating greater reach distances and knee flexion, and fatigue amplified these differences.

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Thomas P. Dompier, Craig R. Denegar, W.E. Buckley, S. John Miller, Jay Hertel and Wayne J. Sebastianelli

Context:

Flexibility is promoted as essential to physical fitness, but the mechanisms limiting it are not fully understood.

Objective:

To investigate the effects of general anesthesia on hamstring extensibility.

Design:

Repeated measures.

Setting:

Hospital operating room.

Subjects:

Eight volunteers undergoing orthopedic surgeries unrelated to the tested limb.

Measurement:

Three measurements of passive knee extension (PKE) taken before and after administration of general anesthesia. The force applied during the measurements was consistent between trials.

Results:

Mean PKE range of motion (ROM) was significantly greater before anesthesia (75.0° ± 11.8°) than after (53.3° ± 17°; t = 5.6, P < .001). Pearson product correlation revealed a significant correlation between the mean difference in PKE ROM between treatment conditions and subjects’ body weight (r = .91, P < .05).

Conclusions:

The findings might be attributable to diminished neural drive to the antagonist muscle groups and suggest a more complex neural control of flexibility than simply neural drive to an agonist muscle.

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Craig R. Denegar, William A. Pitney and Gary B. Wilkerson

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Craig R. Denegar and Giovanni M. Ciriani

Edited by Joe J. Piccininni

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Michael F. Joseph, Katherine Histen, Julia Arntsen, Lauren L’Hereux, Carmine Defeo, Derek Lockwood, Todd Scheer and Craig R. Denegar

Context:

Achilles tendons (ATs) adapt to increased loading generated by long-term adoption of a minimalist shoe running style. There may be difference in the chronology and extent of adaptation between the sexes.

Objective:

To learn the chronology of AT adaptations in female and male runners who transitioned to a minimalist running style through a planned, progressive 12-wk transition program.

Design:

Prospective cohort study of well-trained, traditionally shod runners who transitioned to minimalist shoe running.

Setting:

Repeated laboratory assessment at baseline and 3, 12, and 24 wk after initiating transition program.

Participants:

Fifteen women and 7 men (of 29 enrolled) completed the study.

Main Outcome Measures:

The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force elongation curve and its derivatives at each time point.

Results:

Greater adaptations were observed in men than in women, with men generating more force and having greater increases in CSA, stiffness, and Young’s modulus and less elongation after 12 wk of training.

Conclusion:

Men demonstrated changes in AT properties that were consistent with increased loading of the triceps surae during exercise. The women demonstrated far smaller changes. Further investigation is warranted to understand when adaptations may occur in women and the implications of altered AT mechanical properties for performance and injury risk.