Search Results

You are looking at 1 - 10 of 12 items for

  • Author: Mitchell L. Cordova x
Clear All Modify Search
Restricted access

Mitchell L. Cordova

Restricted access

Mitchell L. Cordova, Lisa S. Jutte and J. Ty Hopkins

Many types of rehabilitation exercises are used to reestablish lower extremity neuromuscular function and strength following ankle injuries. It has not been established which exercise induces the greatest leg muscle activity, which might allow patients to recover more quickly from their injuries. The purpose of this investigation was to establish which exercises induce the most muscle activity in the medial gastrocnemius (MG), peroneus longus (PL), and tibialis anterior (TA), as measured by integrated electromyography (I-EMG). Participants (N = 24, age = 22 ± .59, mass = 63.5 ± 2.1 kg, ht = 165.7 ± 1.2 cm) conducted five repetitions of each of four exercise conditions for 30 s: one-legged stance (OLS), OLS on trampoline (OLST), T-Band kicks (TBK), and OLS perturbations (OLSP). It was found that the TBK exercise induces greater I-EMG in all three muscles, the OLST exercise stimulates more I-EMG activity in the MG and TA, and the OLSP exercise induces greater I-EMG activity in the TA.

Restricted access

Mitchell L. Cordova, Yosuke Takahashi, Gregory M. Kress, Jody B. Brucker and Alfred E. Finch

Objective:

To investigate the effects of external ankle support (EAS) on lower extremity joint mechanics and vertical ground-reaction forces (VGRF) during drop landings.

Design:

A 1 × 3 repeated-measures, crossover design.

Setting:

Biomechanics research laboratory.

Patients:

13 male recreationally active basketball players (age 22.3 ± 2.2 y, height 177.5 ± 7.5 cm, mass 72.2 ± 11.4 kg) free from lower extremity pathology for the 12 mo before the study.

Interventions:

Subjects performed a 1-legged drop landing from a standardized height under 3 different ankle-support conditions.

Main Outcome Measures:

Hip, knee, and ankle angular displacement along with specific temporal (TGRFz1, TGRFz2; s) and spatial (GRFz1, GRFz2; body-weight units [BW]) characteristics of the VGRF vector were measured during a drop landing.

Results:

The tape condition (1.08 ± 0.09 BW) demonstrated less GRFz1 than the control (1.28 ± 0.16 BW) and semirigid conditions (1.28 ± 0.21 BW; P < .0001), and GRFz2 was unaffected. For TGRFz1, no-support displayed slower time (0.017 ± 0.004 s) than the semirigid (0.014 ± 0.001 s) and tape conditions (0.014 ± 0.002 s; P < .05). For TGRFz2, no-support displayed slower time (0.054 ±.006 s) than the semirigid (0.050 ± 0.006 s) and tape conditions (0.045 ± 0.004 s; P < .05). Semirigid bracing was slower than the tape condition, as well (P < .05). Ankle-joint displacement was less in the tape (34.6° ± 7.7°) and semirigid (36.8° ± 9.3°) conditions than in no-support (45.7° ± 7.3°; P < .05). Knee-joint displacement was larger in the no-support (45.1° ± 9.0°) than in the semirigid (42.6° ± 6.8°; P < .05) condition. Tape support (43.8° ± 8.7°) did not differ from the semirigid condition (P > .05). Hip angular displacement was not affected by EAS (F 2,24 = 1.47, P = .25).

Conclusions:

EAS reduces ankle- and knee-joint displacement, which appear to influence the spatial and temporal characteristics of GRFz1 during drop landings.

Restricted access

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.

Restricted access

Charlie A. Hicks-Little, Richard D. Peindl, Tricia J. Hubbard-Turner and Mitchell L. Cordova

Context:

Knee osteoarthritis (OA) is a debilitating disease that affects an estimated 27 million Americans. Changes in lowerextremity alignment and joint laxity have been found to redistribute the medial and/or lateral loads at the joint. However, the effect that changes in anteroposterior knee-joint laxity have on lower-extremity alignment and function in individuals with knee OA remains unclear.

Objective:

To examine anteroposterior knee-joint laxity, lower-extremity alignment, and subjective pain, stiffness, and function scores in individuals with early-stage knee OA and matched controls and to determine if a relationship exists among these measures.

Design:

Case control.

Setting:

Sports-medicine research laboratory.

Participants:

18 participants with knee OA and 18 healthy matched controls.

Intervention:

Participants completed the Western Ontario McMaster (WOMAC) osteoarthritis questionnaire and were tested for total anteroposterior knee-joint laxity (A-P) and knee-joint alignment (ALIGN).

Main Outcome Measures:

WOMAC scores, A-P (mm), and ALIGN (°).

Results:

A significant multivariate main effect for group (Wilks’ Λ = 0.30, F 7,26 = 8.58, P < .0001) was found. Knee-OA participants differed in WOMAC scores (P < .0001) but did not differ from healthy controls on ALIGN (P = .49) or total A-P (P = .66). No significant relationships were identified among main outcome measures.

Conclusion:

These data demonstrate that participants with early-stage knee OA had worse pain, stiffness, and functional outcome scores than the matched controls; however, ALIGN and A-P were no different. There was no association identified among participants’ subjective scores, ALIGN, or A-P measures in this study.

Restricted access

Nicole M. Livecchi, Charles W. Armstrong, Mitchell L. Cordova, Mark A. Merrick and James M. Rankin

Objective:

To compare average electromyogram (EMG) activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) during straight-leg raise (SLR) and knee extension (KE) with the hip in neutral and lateral rotation.

Design:

1 × 4 factorial repeated-measures.

Setting:

Laboratory.

Participants:

13 male college students.

Intervention:

SLR with hip flexed at 40°, in neutral position, and maximally laterally rotated and KE with hip in neutral and maximally laterally rotated.

Main Outcome Measure:

Average EMG activity during each of the 4 conditions, normalized against peak muscle activity during that trial.

Results:

No differences were observed between exercises in VMO activity (F 3,36 = 0.646, P > .05), VL activity (F 3,36 = 1.08, P > .05), or VMO:VL ratio (F 3,36 = 0.598, P > .05).

Conclusions:

Electrical activity of the VMO or VL and VMO:VL ratio do not change with hip position or exercise.

Restricted access

Benjamin D. Armstrong, Mitchell L. Cordova, Christopher D. Ingersoll and Nancy F. Lawrence

Context:

Little research has been done evaluating the effects of muscle soreness on a lifting task.

Objective:

To examine the effects of delayed-onset muscle soreness (DOMS) in the thigh musculature on kinematic and kinetic variables associated with the squat-lifting technique.

Design:

Pretest–posttest repeated measures, with treatment as the independent variable (DOMS and no DOMS of the thigh musculature).

Setting:

Research laboratory.

Participants:

Twenty healthy college students.

Intervention:

Subjects were videotaped lifting a 157-N crate before and after DOMS inducement.

Main Outcome Measures:

A 2-dimensional sagittal-plane video analysis was used to calculate 7 kinematic and kinetic variables.

Results:

DOMS had no effect on L5/S1 torque and shear or compression, hip torque and range of motion, or knee torque and range of motion during lifting.

Conclusions:

DOMS does not appear to alter kinematic and kinetic variables associated with the squat-lifting technique.

Restricted access

Stephen J. Kinzey, Mitchell L. Cordova, Kevin J. Gallen, Jason C. Smith and Justin B. Moore

Objective:

To determine whether a standard 20-min ice-bath (10°C) immersion of the leg alters vertical ground-reaction-force components during a 1 -legged vertical jump.

Design:

A 1 × 5 factorial repeated-measures model was used.

Setting:

The Applied Biomechanics Laboratory at The University of Mississippi.

Participants:

Fifteen healthy and physically active subjects (age = 22.3 ± 2.1 years, height = 177.3 ± 12.2 cm, mass = 76.3 ± 19.1 kg) participated.

Intervention:

Subjects performed 25 one-legged vertical jumps with their preferred extremity before (5 jumps) and after (20 jumps) a 20-min cold whirlpool to the leg. The 25 jumps were reduced into 5 sets of average trials.

Main Outcome Measures:

Normalized peak and average vertical ground-reaction forces, as well as vertical impulse obtained using an instrumented force platform.

Results:

Immediately after cryotherapy (sets 2 and 3), vertical impulse decreased (P = .01); peak vertical ground-reaction force increased (set 2) but then decreased toward baseline measures (P= .02). Average vertical ground-reaction force remained unchanged (P >.05).

Conclusions:

The authors advocate waiting approximately 15 min before engaging in activities that require the production of weight-bearing explosive strength or power.

Restricted access

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.