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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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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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Central Activation Ratio Is a Reliable Measure for Gluteal Neuromuscular Function

Daniel Gilfeather, Grant Norte, Christopher D. Ingersoll, and Neal R. Glaviano

Context: Central activation ratio (CAR) is a common outcome measure used to quantify gross neuromuscular function of the quadriceps using the superimposed burst technique, yet this outcome measure has not been validated in the gluteal musculature. Objective: To quantify gluteus medius (GMed) and gluteus maximus (GMax) CAR in a healthy population and evaluate its validity and reliability over a 1-week period. Design: Descriptive. Setting: Laboratory. Patients or Other Participants: A total of 20 healthy participants (9 males and 11 females; age 22.2 [1.4] y, height 173.4 [11.1] cm, mass 84.8 [25.8] kg) were enrolled in this study. Interventions: Participants were assessed at 2 sessions, separated by 1 week. Progressive electrical stimuli (25%, 50%, 75%, and 100%) were delivered to the GMed and GMax at rest, and 100% stimuli were delivered during progressive hip abduction and extension contractions (25%, 50%, 75%, and 100% maximal voluntary isometric contraction). Main Outcome Measures: GMed and GMax CAR, and hip abduction and hip extension maximal voluntary isometric contraction torque. Line of best fit and coefficient of determination (r 2) were used to assess the relationship between torque output and CAR at varying levels of stimuli. Intraclass correlation coefficients, ICCs(3,k), were used to assess the between-session reliability. Results: GMed CAR was 96.1% (3.4%) and 96.6% (3.2%), on visits 1 and 2, respectively, whereas GMax CAR was 86.5% (7.5%) and 87.2% (10.7%) over the 2 sessions. A third-order polynomial demonstrated the best line of fit between varying superimposed burst intensities at rest for both GMed (r 2 = .156) and GMax (r 2 = .602). Linear relationships were observed in the CAR during progressive contractions with a maximal superimposed burst, GMed (r 2 = .409) and GMax (r 2 = .639). Between-session reliability was excellent for GMed CAR, ICC(3,k) = .911, and moderate for GMax CAR, ICC(3,k) = .704. Conclusion: CAR appears to be an acceptable measure of GMed and GMax neuromuscular function in healthy individuals. Gluteal CAR measurements are reliable measures over a 1-week test period.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 29 (2020): Issue 7 (Sep 2020)

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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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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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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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Effects of Altering Intensity during 1-MHz Ultrasound Treatment on Increasing Triceps Surae Temperature

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.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 13 (2004): Issue 4 (Jan 2004)

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Anterior Shoulder Laxity Is Not Correlated with Medial Elbow Laxity in High School Baseball Players

Brian A. Friscia, Robert R. Hammill, Brian A. McGuire, Jay N. Hertel, and Christopher D. Ingersoll

Context:

Uninjured baseball players have been shown to have increased anterior glenohumeral joint laxity, which may result in adaptive changes at the medial elbow.

Objective:

To determine the relationship between anterior shoulder laxity and medial elbow laxity in both arms of baseball and nonbaseball high school athletes and compare the laxity of dominant and nondominant shoulders and elbows of high school baseball and nonbaseball players.

Design:

Cohort design.

Setting:

Local high schools.

Participants:

Thirty healthy high school male athletes.

Outcome Measures:

Anterior shoulder and medial elbow laxity measurements were taken bilaterally with the Ligmaster™.

Results:

Dominant and nondominant shoulder laxity was significantly greater in the nonbaseball players than the baseball players. No other significant relationships existed.

Conclusions:

High school baseball players exhibit less anterior shoulder laxity than do nonbaseball players. No relationship exists between anterior shoulder and medial elbow laxity in high school baseball players.

Cover Journal of Sport Rehabilitation

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

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The Effect of Textured Insoles on Postural Control in Double and Single Limb Stance

Dawn M. Corbin, Joseph M. Hart, Patrick O. McKeon, Christopher D. Ingersoll, and Jay Hertel

Context:

Increased plantar cutaneous afferent information may improve postural control.

Objective:

To compare postural control measures between balance conditions with and without textured insoles.

Design:

crossover trial.

Setting:

Research Laboratory.

Patients or Other Participants:

33 healthy subjects (27.4 ± 9.1yrs, 172.6 ± 10.3 cm, 75.4 ± 16.4 kg).

Intervention(s):

Subjects performed 24, 10-second bipedal and unilateral stance balance trials with eyes opened and eyes closed, with and without a textured insole in subjects’ shoes.

Main Outcome Measures:

Average velocity and area of center of pressure (COP) excursions.

Results:

We observed an interaction among balance conditions during bilateral stance, but not during unilateral stance. On average, subjects exhibited greater area and velocity of COP excursions with eyes closed compared to eyes opened. Significant differences in area and velocity of COP excursions were observed during bilateral stance only when subjects were not wearing textured insoles. There were no significant differences while subjects balanced in bilateral stance with textured insoles.

Conclusions:

Increased afferent information from textured insoles improves postural control in bilateral stance.

Cover Journal of Sport Rehabilitation

In Journal of Sport Rehabilitation Volume 16 (2007): Issue 4 (Jan 2007)