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Download Regular Verbs Simple Present and Simple Past Tenses and more Exams Business Accounting in PDF only on Docsity! See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/261800767 Adductor Longus Activation During Common Hip Exercises Article  in  Journal of Sport Rehabilitation · May 2014 DOI: 10.1123/JSR.2012-0046 · Source: PubMed CITATIONS 6 READS 3,570 3 authors, including: Kevin Laudner Illinois State University 90 PUBLICATIONS   1,964 CITATIONS    SEE PROFILE Michael Torry Illinois State University 133 PUBLICATIONS   4,536 CITATIONS    SEE PROFILE All content following this page was uploaded by Kevin Laudner on 03 August 2015. The user has requested enhancement of the downloaded file. 79 www.JSR-Journal.com ORIGINAL RESEARCH REPORT Journal of Sport Rehabilitation, 2014, 23, 79-87 http://dx.doi.org/10.1123/JSR.2012-0046 © 2014 Human Kinetics, Inc. The authors are with the School of Kinesiology and Recreation, Illinois State University, Normal, IL. Adductor Longus Activation During Common Hip Exercises Robert J. Delmore, Kevin G. Laudner, and Michael R. Torry Context: Hip-adductor strains are among the most common lower-extremity injuries sustained in athletics. Treatment of these injuries involves a variety of exercises used to target the hip adductors. Objective: To identify the varying activation levels of the adductor longus during common hip-adductor exercises. Design: Descriptive study. Setting: Laboratory. Participants: 24 physically active, college-age students. Intervention: None. Main Measurement Outcomes: Peak and average electromyographic (EMG) activity of the adductor longus muscle during the following 6 hip-adductor rehabilitation exercises: side-lying hip adduction, ball squeezes, rotational squats, sumo squats, standing hip adduction on a Swiss ball, and side lunges. Results: The side-lying hip-adduction exercise produced more peak and average activation than any other exercise (P < .001). Ball squeezes produced more peak and average activation than rotational squats, sumo squats, and standing adduction on a Swiss ball (P < .001). Ball squeezes had more average activation than side lunges (P = .001). All other variables for peak activation during the exercises were not statistically significant (P > .08). These results allowed the authors to provide an overall ranking system (highest to lowest muscle activation): side-lying hip adduction, ball squeezes, side lunges, standing adduction on a Swiss ball, rotational squats, and sumo squats. Conclusion: The study provides a ranking system on the activation levels of the adductor longus muscle for 6 common hip-adductor rehabilitation exercises, with the side-lying hip-adduction and ball-squeeze exercises displaying the highest overall activation. Keywords: therapeutic, rehabilitation, adductor strains Adductor strains are among the most common lower-extremity injuries seen in athletics.1–3 A common mechanism of this injury is when the adductors attempt to decelerate an extending, abducting leg by using an eccentric contraction to adduct and flex the hip.4 With the forceful eccentric contraction, the adductors may not be strong enough to withstand the force, and injury can occur. The injury may also occur during a forceful concentric contraction of the muscle. Lower-extremity athletes such as ice hockey and soccer players are natu- rally more prone to this pathology due to the importance of the hip adductors in lower-extremity performance.4 Research has reported that 10% of all ice hockey injuries sustained are hip-adductor strains.1 Other research has found that 43% of all muscle strains over the course of a hockey season are diagnosed as hip-adductor strains.2 Another investigation looking solely at adductor/ abdominal-strain incidence in all U.S. National Hockey League teams over 6 competitive seasons reported that out of 7050 ice hockey players, 617 adductor/abdominal strains were reported, with adductor strains being the most common compared with abdominal strains.3 Soccer athletes also frequently sustain hip-adductor muscle injuries, with 12% to 18% of all soccer-related injuries being diagnosed as adductor strains.5,6 Sixty percent of these injuries are due to overuse, while the other 40% are caused by acute trauma.5 Experience level has also been shown to increase the incidence of adduc- tor strains in soccer, with athletes in higher experience levels reporting more adductor strains.6 In the adductor muscle group, the adductor longus has been shown to be most susceptible to injury when the leg is transitioning from hip extension to hip flexion during a soccer kick.7 This is a common action not only in soccer but also in any sport requiring forceful hip flexion and extension. Hockey players perform a similar motion while skating, making the mechanism of hip-adductor injury common in both soccer and hockey. The adductor longus muscle has been found to be the most frequently injured of the adductor group, with 62% of adductor injuries occurring to the musculotendinous junction of the adductor longus.8 With adductor strains being such a common injury among different athletes, understanding how the adductor longus muscle specifi- cally functions during different exercises becomes a key component in the prevention and treatment of such inju- ries. With the occurrence of hip-adductor strains being 17 times more likely when hip-adductor strength is 80% or less than the strength of the abductors,9 this makes 82 Delmore, Laudner, and Torry aspects of both knees (Figure 3). The participant was asked to adduct his hips, thereby squeezing the ball, and then return to the starting position. The participant was instructed to squeeze the ball at submaximal intensity, enough to indent the ball slightly. Rotational squats were performed by having the participant stand with his feet shoulder width apart and knees slightly flexed. A circular resistance band (Thera- Band, red: medium resistance, 28 in) was placed around both knees, just proximal to the joint (Figure 4). The Figure 3 — Ball squeeze. Figure 4 — Rotational squat. Black arrow indicates direction of force of the participant. Adductor Longus Activation During Exercises 83 participant was asked to rotate his trunk approximately 80° to 90° while externally rotating the hip 80° to 90° away from the midline of the body, so the test foot was pointing at a 90° angle from the nontest foot. While turn- ing, the participant was asked to simultaneously squat by flexing at the knees and then extend to return to the start position with both feet facing forward. Sumo squats began with the feet shoulder width apart and rotated away from the midline of the body at approximately a 45° angle. In this position, the participant was then asked to flex at the hips and knees into a squat- ting position (to approximately 90°) and then return to the starting position by extending both legs (Figure 5). Standing hip adduction on a Swiss ball began with the test knee flexed and resting on a 75-cm Swiss ball (TheraBand, Akron, OH). The participant was then asked to move the test leg away from the midline of the body by rolling the Swiss ball out and then bring the test leg back toward the midline of the body to the starting posi- tion (Figure 6). Side lunges were performed by having the participant step to the side while facing forward, allowing both knees to flex to 90° and keeping the back straight (Figure 7). The step was double the length of the distance between the feet when they are shoulder width apart. The participants alternated stepping to the right and then to the left to keep close proximity to the EMG equipment. Figure 5 — Sumo squat. Black arrow indicates direction of force of the participant. Figure 6 — Standing hip adduction on a Swiss ball. Black arrow indicates direction of force of the participant. Figure 7 — Side lunge. Black arrow indicates direction of force of the participant. 84 Delmore, Laudner, and Torry Statistical Methods The MVIC raw signal was full-wave rectified and pro- cessed using a root-mean-square of 100 milliseconds. For the MVICs, the average of the highest peak activation of 3 of 5 trials was used for trial data normalization. Trial data were processed for peak and average activation. After the raw signal was rectified and smoothed, it was divided by the respective MVIC value to yield percentage activation values. Peak %MVIC activation trials were processed by taking the highest value in each repetition of each exercise. Average %MVIC activation trials were processed by averaging all the activity for each repetition for each exercise. Using PASW version 18 (PASW Inc, Chicago, IL), a 1-way repeated-measures analyses of variance (ANOVA) was conducted to compare average and peak EMG-signal amplitude between the exercises. A Bonferroni correction was used to protect against type I error caused by mul- tiple tests (P < .05/6, or P < .008). To ensure that EMG values were consistent within each exercise and during the MVICs, reliability analyses were also conducted using intraclass correlation coefficients (ICC3,1). The rank of the exercises was determined by rank of highest peak and average amplitude and then viewed as an overall rank. When a discrepancy existed between exercises in regard to the order of peak rank and average rank, the sum of the peak and average rank was determined and used to determine the placement of the exercise within the ranking system. Results The side-lying hip-adduction exercise produced more peak %MVIC activation than ball squeezes (24.1%, P = .001), side lunges (33.4%, P = .001), standing adduc- tion on a Swiss ball (42.8%, P = .001), rotational squats (44.3%, P = .001), and sumo squats (46.4%, P = .001). Ball squeezes produced more peak %MVIC activation than standing adduction on a Swiss ball (18.7%, P = .001), rotational squats (20.2%, P = .001), and sumo squats (22.3%, P = .001). All other variables for peak %MVIC activation during the exercises were not statisti- cally significant (P > .08). Side-lying hip adduction produced more average %MVIC activation than ball squeezes (8.1%, P = .001), side lunges (13.9%, P = .001), rotational squats (15.3%, P = .001), standing adduction on a Swiss ball (16.0%, P = .001), and sumo squats (16.4%, P = .001). Ball squeezes produced more average %MVIC activation than side lunges (5.8%, P = .001), rotational squats (7.2%, P = .001), standing adduction on a Swiss ball (7.9%, P = .001), and sumo squats (8.3%, P = .001). The percentages in the parentheses represent the difference in percentage activation between exercises. All other variables for average %MVIC activation during the exercises were not statistically significant (P > .42). Peak and average %MVIC activation of adductor longus across all exercises are displayed in Table 1. Reliability analysis revealed ICC3,1 values of .98 to .99 when assessing all 5 repetitions of each exercise. When we assessed reliability between the 3 MVIC repeti- tions, the ICC value was found to be .93. These values are displayed in Table 2 and suggest there was strong reliability within subjects throughout each exercise and the MVIC trials. The means and standard deviations for all normalized peak and average amplitude data can be viewed in Table 1. Based on these data each exercise was ranked from highest to lowest muscle activity of the adductor longus (Table 3). Table 1 Peak and Average EMG Amplitudes (as %MVIC) of Adductor Longus Across 6 Exercises Exercise % peak amplitude MVIC (SD) % average amplitude MVIC (SD) Side-lying hip adduction 60.1 (16.2)* 22.4 (5.5)† Ball squeezes 36.0 (18.0)+ 14.3 (6.0)‡ Rotational squats 15.8 (10.7) 7.1 (4.3) Sumo squats 13.7 (7.6) 6.0 (3.0) Standing hip adduction on Swiss ball 17.3 (9.7) 6.4 (3.1) Side lunges 26.7 (13.1) 8.5 (3.9) Abbreviations: EMG, electromyography; MVIC, maximum voluntary isometric contraction. Significance was set at P = .001, with a symbol indi- cating significance. *Side-lying hip adduction produced more peak activation than ball squeezes, rotational squats, sumo squats, standing adduction on Swiss ball, and side lunges. +Ball squeezes produced more peak activation than rotational squats, sumo squats, and standing adduction on Swiss ball. †Side-lying hip adduction produced more average activation than ball squeezes, rotational squats, sumo squats, standing adduction on Swiss ball, and side lunges. ‡Ball squeezes produced more average activation than rotational squats, sumo squats, standing adduction on Swiss ball, and side lunges.