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Isotonic Contractions Might Be More Effective than Isokinetic Contractions in Developing Muscle Strength

Kenneth L Knight, Christopher D Ingersoll, and John Bartholomew

Problem:

Isokinetic contractions are thought to be superior to isotonic contractions for developing strength because resistance during them is greater. Because isokinetic resistance is accommodating, however, it decreases with fatigue. It is constant during multiple repetitions, so an aggressive isotonic procedure should produce more force as the muscle fatigues, which would be an advantage in strength development.

Purpose:

To compare force production in isokinetic and isotonic muscle contractions at the beginning and end of a set of fatiguing repetitions.

Methods:

Subjects performed 25 maximal-effort isokinetic knee extensions at 60°/s. After 25–72 hours, they performed maximal repetitions isotonically using 70% of the isokinetic peak torque with speed set at a maximum of 300°/s.

Results:

Peak force during the first 3 repetitions was greater isokinetically, but average force was similar. During the last 3 repetitions, isotonic force was higher than isokinetic force.

Conclusion:

Muscle is more active as it nears fatigue during an isotonic contraction. These data support the hypothesis that isotonic contractions recruit extra motor units at the point of fatigue.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 10 (2001): Issue 2 (Jan 2001)

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Single-Leg Landing Strategy after Knee-Joint Cryotherapy

Joseph M. Hart, Jamie L. Leonard, and Christopher D. Ingersoll

Context:

Despite recent findings regarding lower extremity function after cryotherapy, little is known of the neuromuscular, kinetic, and kinematic changes that might occur during functional tasks.

Objective:

To evaluate changes in ground-reaction forces, muscle activity, and knee-joint flexion during single-leg landings after 20-minute knee-joint cryotherapy.

Design:

1 × 4 repeated-measures, time-series design.

Setting:

Research laboratory.

Patients or Other Participants:

20 healthy male and female subjects.

Intervention:

Subjects performed 5 single-leg landings before, immediately after, and 15 and 30 minutes after knee-joint cryo-therapy.

Main Outcome Measures:

Ground-reaction force, knee-joint flexion, and muscle activity of the gastrocnemius, hamstrings, quadriceps, and gluteus medius.

Results:

Cryotherapy did not significantly (P > .05) change maximum knee-joint flexion, vertical ground-reaction force, or average muscle activity during a single-leg landing.

Conclusion:

Knee-joint cryotherapy might not place the lower extremity at risk for injury during landing.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 14 (2005): Issue 4 (Jan 2005)

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Facilitation of Hoffmann Reflexes of Ankle Muscles in Prone but Not Standing Positions by Focal Ankle-Joint Cooling

Kyung-Min Kim, Christopher D. Ingersoll, and Jay Hertel

Context:

Focal ankle-joint cooling (FAJC) has been shown to increase Hoffmann (H) reflex amplitudes of select leg muscles while subjects lie prone, but it is unknown whether the neurophysiological cooling effects persist in standing.

Objective:

To assess the effects of FAJC on H-reflexes of the soleus and fibularis longus during 3 body positions (prone, bipedal, and unipedal stances) in individuals with and without chronic ankle instability (CAI).

Design:

Crossover.

Setting:

Laboratory.

Participants:

15 young adults with CAI (9 male, 6 female) and 15 healthy controls.

Intervention:

All subjects received both FAJC and sham treatments on separate days in a randomized order. FAJC was accomplished by applying a 1.5-L plastic bag filled with crushed ice to the ankle for 20 min. Sham treatment involved room-temperature candy corn.

Main Outcome Measures:

Maximum amplitudes of H-reflexes and motor (M) waves were recorded while subjects lay prone and then stood in quiet bipedal and unipedal stances before and immediately after each treatment. Primary outcome measures were Hmax:Mmax ratios for the soleus and fibularis longus. Three-factor (group × treatment condition × time) repeated-measures ANOVAs and Fisher LSD tests were performed for statistical analyses.

Results:

Significant interactions of treatment condition by time for prone Hmax:Mmax ratios were found in the soleus (P = .001) and fibularis longus (P = .003). In both muscles, prone Hmax:Mmax ratios moderately increased after FAJC but not after sham treatment. The CAI and healthy groups responded similarly to FAJC. In contrast, there were no significant interactions or main effects in the bipedal and unipedal stances in either muscle (P > .05).

Conclusions:

FAJC moderately increased H-reflex amplitudes of the soleus and fibularis longus while subjects were prone but not during bipedal or unipedal standing. These results were not different between groups with and without CAI.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 24 (2015): Issue 2 (Jan 2015)

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Delayed-Onset Muscle Soreness Does Not Alter the Kinematics and Kinetics of the Squat-Lifting Technique

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.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 10 (2001): Issue 3 (Jan 2001)

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Lower Extremity EMG in Male and Female College Soccer Players during Single-Leg Landing

J. Craig Garrison, Joe M. Hart, Riann M. Palmieri, D. Casey Kerrigan, and Christopher D. Ingersoll

Context:

Gender differences in muscle activity during landing have been studied as a possible contributing factor to the greater incidence of anterior cruciate ligament injuries in women.

Objective:

To compare root-mean-square (RMS) electromyography (EMG) of selected lower extremity muscles at initial contact (IC) and at peak knee internal-rotation (IR) moment in men and women during landing.

Design:

Preexperimental design static-group comparison.

Setting:

Motion-analysis laboratory.

Participants:

16 varsity college soccer players (8 men, 8 women).

Main Outcome Measures:

EMG activity of the gluteus medius, lateral hamstrings, vastus lateralis, and rectus femoris during landing.

Results:

When RMS EMG of all muscles was considered simultaneously, no significant differences were detected between genders at IC or at peak knee IR moment.

Conclusion:

Male and female college soccer players display similar relative muscle activities of the lower extremity during landing. Gender landing-control parameters might vary depending on the technique used to analyze muscle activity.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 14 (2005): Issue 1 (Jan 2005)

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Comparison of Knee-Joint Moments in Male and Female College Soccer Players during a Single-Leg Landing

J. Craig Garrison, Joe M. Hart, Riann M. Palmieri, D. Casey Kerrigan, and Christopher D. Ingersoll

Context:

Although kinematic analyses are helpful in describing movement differences between genders, kinetic data might further explain the predisposing factors contributing to potential injury during athletic landing maneuvers.

Objective:

To determine whether there are differences in knee moments between male and female varsity college soccer players during a single-leg landing.

Design:

Preexperimental with static group comparison.

Setting:

Motion-analysis laboratory.

Participants:

16 varsity college soccer players (8 men, 8 women).

Intervention:

Subjects performed 5 single-leg landings from a height of 60 cm.

Main Outcome Measures:

Peak internal rotation, valgus, varus, and extension knee moments calculated from raw ground-reaction forces and kinematic data.

Results:

Significant gender differences were present (P = .020), with men exhibiting 31% greater mean peak knee-varus moments than women when landing on a single leg from 60 cm (P = .020).

Conclusions:

Male soccer players demonstrate greater knee-varus moments than female soccer players during single-leg landing. This might be valuable in designing clinical treatment and prevention programs for ACL injuries.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 14 (2005): Issue 4 (Jan 2005)

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Lower Extremity Joint Moments of Collegiate Soccer Players Differ between Genders during a Forward Jump

Joseph M. Hart, J. Craig Garrison, Riann Palmieri-Smith, D. Casey Kerrigan, and Christopher D. Ingersoll

Context:

Lower extremity kinetics while performing a single-leg forward jump landing may help explain gender biased risk for noncontact anterior cruciate ligament injury.

Objective:

Gender comparison of lower extremity joint angles and moments.

Design:

Static groups comparison.

Setting:

Motion analysis laboratory.

Patients or Other Participants:

8 male and 8 female varsity, collegiate soccer athletes.

Intervention:

5 single-leg landings from a 100cm forward jump.

Main Outcome Measures:

Peak and initial contact external joint moments and joint angles of the ankle, knee, and hip.

Results:

At initial heel contact, males exhibited a adduction moment whereas females exhibited a abduction moment at the hip. Females also had significantly less peak hip extension moment and significantly less peak hip internal rotation moment than males had. Females exhibited greater knee adduction and hip internal rotation angles than men did.

Conclusions:

When decelerating from a forward jump, gender differences exist in forces acting at the hip.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 17 (2008): Issue 2 (Jan 2008)

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Quadriceps Concentric EMG Activity Is Greater than Eccentric EMG Activity during the Lateral Step-Up Exercise

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.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 9 (2000): Issue 2 (Jan 2000)

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The Relationship of Ankle Temperature during Cooling and Rewarming to the Human Soleus H Reflex

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.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 9 (2000): Issue 3 (Jan 2000)

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Altered Plantar-Receptor Stimulation Impairs Postural Control in Those With Chronic Ankle Instability

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.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 21 (2012): Issue 1 (Jan 2012)