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Patrick O. McKeon, Alex J. Stein, Christopher D. Ingersoll, and Jay Hertel

Context:

Postural control as assessed via time-to-boundary (TTB) measures has been shown to be impaired in those with chronic ankle instability (CAI). Foot orthotics have been shown to improve postural control, although it is not clear if this is via mechanical or sensorimotor mechanisms.

Objective:

To assess the effect of textured shoe inserts that provide no mechanical support on postural control as assessed by TTB measures in subjects with CAI.

Design:

A crossover design to examine the effects of a textured insole on postural control in individuals with unilateral CAI. The independent variables were vision (eyes open, eyes closed) and texture (textured insole, sham insole, control).

Setting:

Laboratory.

Participants:

20 physically active individuals, 12 men, 8 women, age 18–45 y (21.5 ± 5.51) with self-reported CAI.

Intervention:

Each subject balanced in shod single-limb stance with eyes open and eyes closed under 3 conditions (control, sham, and textured insole). The order of testing under the 3 shoe conditions and 2 vision conditions was counterbalanced.

Main Outcome Measures:

The mean of TTB minima and the standard deviation of TTB minima in the mediolateral (ML) and anteroposterior directions.

Results:

There were significant reductions in TTB ML magnitude and variability found in the textured condition compared with the control and sham conditions. In the textured condition, subjects failed significantly more trials than any other condition.

Conclusions:

Stimulating the plantar surface of the foot, via a textured insole, has an effect in the broad spectrum of postural-control maintenance in individuals with CAI.

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Jihong Park, Terry L. Grindstaff, Joe M. Hart, Jay N. Hertel, and Christopher D. Ingersoll

Context:

Weight-bearing (WB) and non-weight-bearing (NWB) exercises are commonly used in rehabilitation programs for patients with anterior knee pain (AKP).

Objective:

To determine the immediate effects of isolated WB or NWB knee-extension exercises on quadriceps torque output and activation in individuals with AKP.

Design:

A single-blind randomized controlled trial.

Setting:

Laboratory.

Participants:

30 subjects with self-reported AKP.

Interventions:

Subjects performed a maximal voluntary isometric contraction (MVIC) of the quadriceps (knee at 90°). Maximal voluntary quadriceps activation was quantified using the central activation ratio (CAR): CAR = MVIC/(MVIC + superimposed burst torque). After baseline testing, subjects were randomized to 1 of 3 intervention groups: WB knee extension, NWB knee extension, or control. WB knee-extension exercise was performed as a sling-based exercise, and NWB knee-extension exercise was performed on the Biodex dynamometer. Exercises were performed in 3 sets of 5 repetitions at approximately 55% MVIC. Measurements were obtained at 4 times: baseline and immediately and 15 and 30 min postexercise.

Main Outcome Measures:

Quadriceps torque output (MVIC: N·m/Kg) and quadriceps activation (CAR).

Results:

No significant differences in the maximal voluntary quadriceps torque output (F 2,27 = 0.592, P = .56) or activation (F 2,27 = 0.069, P = .93) were observed among the 3 treatment groups.

Conclusions:

WB and NWB knee-extension exercises did not acutely change quadriceps torque output or activation. It may be necessary to perform exercises over a number of sessions and incorporate other disinhibitory interventions (eg, cryotherapy) to observe acute changes in quadriceps torque and activation.

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Rebecca J. Guthrie, Terry L. Grindstaff, Theodore Croy, Christopher D. Ingersoll, and Susan A. Saliba

Context:

Individuals with low back pain (LBP) are thought to benefit from interventions that improve motor control of the lumbopelvic region. It is unknown if therapeutic exercise can acutely facilitate activation of lateral abdominal musculature.

Objective:

To investigate the ability of 2 types of bridging-exercise progressions to facilitate lateral abdominal muscles during an abdominal drawing-in maneuver (ADIM) in individuals with LBP.

Design:

Randomized control trial.

Setting:

University research laboratory.

Participants:

51 adults (mean ± SD age 23.1 ± 6.0 y, height 173.6 ± 10.5 cm, mass 74.7 ± 14.5 kg, and 64.7% female) with LBP. All participants met 3 of 4 criteria for stabilization-classification LBP or at least 6 best-fit criteria for stabilization classification.

Interventions:

Participants were randomly assigned to either traditional-bridge progression or suspension-exercise-bridge progression, each with 4 levels of progressive difficulty. They performed 5 repetitions at each level and were progressed based on specific criteria.

Main Outcome Measures:

Muscle thickness of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) was measured during an ADIM using ultrasound imaging preintervention and postintervention. A contraction ratio (contracted thickness:resting thickness) of the EO, IO, and TrA was used to quantify changes in muscle thickness.

Results:

There was not a significant increase in EO (F 1,47 = 0.44, P = .51) or IO (F 1,47 = .30, P = .59) contraction ratios after the exercise progression. There was a significant (F 1,47 = 4.05, P = .05) group-by-time interaction wherein the traditional-bridge progression (pre = 1.55 ± 0.22; post = 1.65 ± 0.21) resulted in greater (P = .03) TrA contraction ratio after exercise than the suspension-exercise-bridge progression (pre = 1.61 ± 0.31; post = 1.58 ± 0.28).

Conclusion:

A single exercise progression did not acutely improve muscle thickness of the EO and IO. The magnitude of change in TrA muscle thickness after the traditional-bridging progression was less than the minimal detectable change, thus not clinically significant.

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Riann M. Palmieri, Christopher D. Ingersoll, Marcus B. Stone, and B. Andrew Krause

Objective:

To define the numerous center-of-pressure derivatives used in the assessment of postural control and discuss what value each might provide in the assessment of balance.

Data Sources:

MEDLINE and SPORTDiscus were searched with the terms balance, postural control, postural sway, and center of pressure. The remaining citations were collected from references of similar papers. A total of 67 references were studied.

Conclusions:

Understanding what is represented by each parameter used to assess postural control is crucial. At the present time the literature has failed to demonstrate how the variables reflect changes made by the postural-control system. Until it can be shown that the center of pressure and its derivatives actually reveal changes in the postural-control system, the value of using these measures to assess deficits in postural control is minimized.

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Phillip O. Burr, Timothy J. Demchak, Mitchell L. Cordova, Christopher D. Ingersoll, and Marcus B. Stone

Context:

It has been suggested that to obtain optimal physiological effects of heating, musculoskeletal temperature (TEMP) should be elevated 3 °C above baseline and maintained for at least 5 min.

Objective:

To identify a multi-intensity ultrasound protocol that will achieve optimal heating.

Design:

1 × 2 between-subjects.

Setting:

Sports-injury research laboratory.

Participants:

20 healthy volunteers.

Interventions:

A 2.5-min treatment at 2.4 W/cm2 immediately followed by a 7.5-min treatment at 1.0 W/cm2 (T1) and a 10-min treatment at 1.5 W/cm2 (T2).

Outcome Measures:

TEMP change during the first 2.5 min of ultrasound treatment (°C), time the TEMP was ≥3 °C above baseline during and after the treatment.

Results:

T1 increased TEMP during the first 2.5 min of the ultrasound treatment (3.22 ± 1.25 °C) more than T2 did (1.68 ± 0.72 °C). No difference was found for the remaining measures.

Conclusions:

The multi-intensity protocol (2.4 W/cm2 and 1.0 W/cm2) did not result in optimal heating.

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Angie Selseth, Marilyn Dayton, Mitchell L. Cordova, Christopher D. Ingersoll, and Mark A. Merrick

Purpose:

To analyze vastus medialis obliquus (VMO) and vastus lateralis (VL) muscle activity during the concentric and eccentric phases of a lateral step-up exercise.

Design:

Repeated-measures. Dependent variable: the integrated electromyogram measured as a percentage of the maximal voluntary isometric contraction of the VMO and VL muscles. Independent variable: muscle contraction with 2 levels (concentric and eccentric).

Subjects:

Twenty-three volunteers with no previous history of knee surgery or anterior knee pain.

Methods:

Surface electrodes were positioned over the VMO and VL, and electromyographic data were collected during the exercise.

Results:

The 2 muscle phases of contraction were different when both dependent variables were considered simultaneously (F 2,7 = 33.2, P < .001). Concentric contractions produced greater muscle activity for VL (P < .05) and VMO (P < .05).

Conclusions:

Because concentric contractions produce greater activity than eccentric contractions do during the lateral step-up exercise, they provide a stronger stimulus for muscle activation, which might result in greater muscle strength gains.

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B. Andrew Krause., J. Ty Hopkins, Christopher D. Ingersoll, Mitchell L. Cordova, and Jeffrey E. Edwards

Objective:

Correlate skin temperature and motoneuron-pool recruitment during cooling and rewarming.

Design:

Within-subjects, correlational analysis. H reflex was correlated to ankle-skin temperature over time using a Pearson product-moment correlation coefficient and a coefficient of determination (R2).

Subjects:

Ten healthy, physically active college students.

Measurements:

Soleus H reflex and ankle-skin interface temperature were measured during ice application and rewarming. Electrical stimulation was delivered to produce 75% of each subject's maximum H reflex.

Results:

Ankle cooling (r = −.95, P < .05) exhibited a strong inverse relationship with soleus H reflex. A positive correlation was observed between rewarming (r = .74, P < .05) and soleus H reflex.

Conclusions:

Temperature accounts for nearly 90% (R2 = .90) of the variability in the soleus H reflex during cooling and 55% (R2 = .55) during rewarming, suggesting that more motoneurons are recruited as temperature decreases. These interactions appear to involve both local and central nervous system functions.

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Lindsay K. Drewes, Patrick O. McKeon, Gabriele Paolini, Patrick Riley, D. Casey Kerrigan, Christopher D. Ingersoll, and Jay Hertel

Context:

Kinematic patterns during gait have not been extensively studied in relation to chronic ankle instability (CAI).

Objective:

To determine whether individuals with CAI demonstrate altered ankle kinematics and shank-rear-foot coupling compared with controls during walking and jogging.

Design:

Case control.

Setting:

Motion-analysis laboratory.

Participants:

7 participants (3 men, 4 women) suffering from CAI (age 24.6 ± 4.2 y, height 172.6 ± 9.4 cm, mass 70.9 ± 8.1 kg) and 7 (3 men, 4 women) healthy, matched controls (age 24.7 ± 4.5 y, height 168.2 ± 5.9 cm, mass 66.5 ± 9.8 kg).

Interventions:

Subjects walked and jogged on a treadmill while 3-dimensional kinematics of the lower extremities were captured.

Main Outcome Measures:

The positions of rear-foot inversion–eversion and shank rotation were calculated throughout the gait cycle. Continuous relative-phase angles between these segments were calculated to assess coupling.

Results:

The CAI group demonstrated more rear-foot inversion and shank external rotation during walking and jogging. There were differences between groups in shank-rear-foot coupling during terminal swing at both speeds.

Conclusions:

Altered ankle kinematics and joint coupling during the terminal-swing phase of gait may predispose a population with CAI to ankle-inversion injuries. Less coordinated movement during gait may be an indication of altered neuromuscular recruitment of the musculature surrounding the ankle as the foot is being positioned for initial contact.

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Michael G. Dolan, Brian G. Pietrosimone, J. Ty Hopkins, and Christopher D. Ingersoll

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John McCleve, Luke Donovan, Christopher D. Ingersoll, Charles Armstrong, and Neal R. Glaviano

Altered arthrokinematics are present in individuals with chronic ankle instability, which may influence their walking biomechanics. The objective of this study was to determine if fibular reposition tape (FRT) has any effect on lower extremity kinematics, kinetics, and vertical ground reaction forces (vGRFs) during gait in individuals with chronic ankle instability (CAI). Twenty active individuals with bilateral CAI received three conditions: FRT, sham FRT, and no tape. Ten trials of walking were collected for each condition to evaluate lower extremity kinematics, kinetics, and vGRF. Curve analyses were used to compare conditions by plotting group means and 90% confidence intervals. There were no significant differences in lower extremity biomechanics between any tape conditions. Application of FRT did not have any effect on triplanar kinematics, kinetics, or vGRF during gait in individuals with CAI.