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The effects of a lumbopelvic-hip strengthening intervention program on functional testing in collegiate female tennis players.

INTRODUCTION

Coordinated movement is produced from sequential muscle activation proximal to distal throughout the kinetic chain (29). The kinetic chain is the body's arrangement of segmental links that allow for both coordinated and efficient movement. The efficiency of the kinetic chain is based on sequential muscle activation from the proximal aspect or lower extremity and torso musculature to the more distal upper extremity musculature. The synergistic muscle activation from proximal to distal allows for postural awareness that can control and correct disturbances in equilibrium (5,14,32). It is coordinated movements of the lumbopelvic-hip complex (LPHC) that provide the ability to maintain or resume torso positioning, or postural awareness after static and dynamic muscular contractions (33). The lumbopelvic-hip complex is composed of the hip, pelvis, and trunk segments, including the musculature either originating from or attaching on the hip, pelvis, and trunk. Thus, it is vital to have efficient functioning of the LPHC during all forms of segmental movement (1,16,29,30).

By virtue of the kinetic chain, the importance of the LPHC in coordinated movements is invaluable. However, in addition to coordinated movements, the effectiveness of the LPHC plays a vital role in injury prevention (4,14,16,31). If the LPHC is unstable, then there is postural collapse (27,31). Biomechanically, postural collapse does not allow for efficient segmental movement and ultimately predisposes one to injury (6,16,31,33). Knee injuries are commonly associated with decreased neuromuscular control of the lumbopelvic-hip complex (LPHC) resulting in alterations of hip and trunk positioning (33). Lack of neuromuscular awareness of the LPHC has been associated with increased hip varus, hip flexion, and knee valgus during jumping or landing activities, which has ultimately led to high-risk knee injury positions (15).

Hewett and colleagues (9) have shown that insufficient neuromuscular control of lower extremity biomechanics leads to potential patterns for high-risk injury. In addition, others have examined neuromuscular control at the hip and described neuromuscular insufficiencies resulting in dynamic knee valgus thus creating high-risk injury potential patterns (13,33). Much of the high-risk patterns involve increased hip adduction contributing to dynamic knee valgus (13,8).

Chimera, Swanik, Swanik, & Straub, (3) have described plyometrics as training not only musculature strength and function, but also enhancing neuromuscular stimulation. Training that targets neural pathways tasked with coordinated movement is thought to affect the feed forward and feedback mechanisms that allow for regulation of movement by the brain. The basis of the feed forward mechanism is neural control during the landing phase of the jump. It is thought that the feed forward mechanism prepares the body for the impact based on the expectations of the brain. The brain takes into account past experience, height, and velocity of jump and activates the musculature accordingly (3). Understanding the neural responses associated plyometric training will allow for safe and efficient plyometric training.

There have been numerous studies examining intervention programs and injury reduction (9,17,19-23), with the most successful programs incorporating plyometric and neuromuscular technique training (10,17,25,26). Ideally the training is sport-specific and facilitates proprioceptive adaptions (19). Recently, focus has been on providing clinicians a 'user-friendly' assessment tool to screen injury susceptibility through identifying landing technique flaws by means of a Tuck Jump Assessment (19). The Tuck Jump Assessment examines five modifiable risk factors: (1) ligament dominance; (2) quadriceps dominance; (3) leg dominance or residual injury deficits; (4) trunk dominance (LPHC dysfunction); and (4) technique perfection. This assessment tool has shown a high intra-rater reliability (R=0.83) in the ability to adequately identify landing technique flaws (24). In addition to utilizing the Tuck Jump Assessment as a predictor of injury susceptibility through high-risk landing mechanics, it is also used to improve neuromuscular control during difficult jump and landing sequences. The neuromuscular assessment in the tuck jump are those that are utilized in most plyometric programs that are utilized in most sporting activities; those activities or sport that are jump dominant and even non jump dominant activities.

With the importance of neuromuscular control of lower extremity biomechanics during dynamic movements as well as the integral magnitude of the LPHC in dynamic movements, it was the purpose of this study to examine a LPHC conditioning program and its effects on Tuck Jump Assessment scores in National Collegiate Athletic Associate Division I female tennis athletes. It was hypothesized that Tuck Jump Assessment Scores would improve after the LPHC intervention.

METHODS

Study Design

A convenient sample was utilized to examine pre and post effects of a 16-week LPHC intervention program on functional performance as measured by the Tuck Jump Assessment. The Tuck Jump Assessment (24) was conducted on the first day and the last day of the intervention program. All measurements were collected by the primary investigator, a certified athletic trainer with experience in assessing the Tuck Jump, and recorded by an athletic training student.

Participants

Participants were selected from a convenience sample of seven National Collegiate Athletic Association Division I female tennis athletes (19.7 [+ or -] .95 years; 167.3 [+ or -] 7.4 cm; and 60.72 kg [+ or -] 6.71 kg). Participants were excluded if they had a history of any type of lower extremity or lumbopelvic-hip complex injury at the time of data collection. In addition, all participants had to be injury free for the past six months. The University of Arkansas Institutional Review Board approved all testing protocols used in the current study. Prior to participant participation, the approved procedures, risks, and benefits were explained to all participants. Informed consent was obtained from the participant, and the rights of the participants were protected according to the guidelines of the University's Institutional Review Board.

Procedure

Prior to the LPHC intervention, all participants performed the Tuck Jump Assessment. The Tuck Jump Assessment was utilized to assess landing techniques during the plyometric activity of jumping (24). The Tuck Jump Assessment was performed in the athletic training room and recorded by a series of still frame photographs. Prior to the assessment, participants were instructed to start in the athletic position with feet shoulder width apart, jump with a slight crouch downward and extend arms behind. Then swing arms forward while simultaneously jumping straight up and pull knees up as high as possible and pull thighs parallel to ground. Then upon landing immediately begin the next jump. Participants were encouraged to land softly and in same footprint for each jump. They were instructed to perform the series of tuck jumps for 10 seconds. Participants were evaluated on ten characteristics: (1) lower extremity valgus at landing; (2) thighs parallel at peak of jump; (3) thighs equal side-to-side; (4) foot placement shoulder width apart; (5) parallel foot placement; (6) equal timing of foot contact; (7) excessive contact noise; and (8) pauses between jumps (24). If the participant presented with any of the 10 characteristics within her tuck jump testing, she was given a point. One point was awarded for each flaw present for a total of 10 points.

Lumbopelvic-hip Complex Intervention Program

The LPHC intervention program consisted of six minutes of five body weight exercises prior to every organized team practice during the course of the pre-season and competitive season (16 weeks) and directly supervised by the team's certified athletic trainer (ATC). The intervention program consisted of a total of 10 exercises (Figures 1-10) that were randomly alternated throughout the treatment days so that five exercises were performed every day of the intervention. All participants were compliant with the LPHC program and were monitored throughout the duration of the intervention by their ATC.

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Statistical Analysis

A paired sample t-test was used to evaluate the differences in Tuck Jump scores prior to the LPHC intervention and immediately following. Alpha was set a priori < 0.05.

RESULTS

Descriptive statistics revealed that pre-test scores were 8.7 [+ or -] 1.5 while post-test scores were 6.7 [+ or -] 1.1 for the Tuck Jump Assessment. Statistical analyses were performed using SPSS 15.0 (Chicago, IL, USA). The paired sample t-test revealed there was a significant improvement in the Tuck Jump scores following the LPHC intervention program (p = .004) (See Figure 11).

DISCUSSION

Female athletes have a four-to-six times greater risk of sustaining a lower extremity injury than their male counterparts (11). One explanation for the discrepancy in injury rates is increased dynamic knee valgus caused by neuromuscular imbalances. It has been suggested that female athletes have decreased activation of the LPHC, a muscle group that is necessary to control the forces transmitted through the body in order to maximize efficiency of all upper and lower body movements (15). Fortunately, dynamic knee valgus can be improved with neuromuscular training that focuses on activation of the LPHC (2,25). Therefore, the purpose of this study was to determine if implementing a LPHC conditioning program improved neuromuscular deficiencies.

Though there was statistical significance in Tuck Jump Assessment score improvements, the clinical significance of this study is colossal. All participants improved their Tuck Jump Assessment scores. It should be noted that throughout the intervention program there was no jump landing type of training. Participants were active in their competitive tennis season and performed the LPHC intervention prior to all organized practices. Therefore, improvements could have been the result of adopting new muscle recruitment patterns that helped subjects deal with the stresses of landing. One would believe such recruitment patterns would involve activation of the lumbopelvic hip complex. This idea is supported by Hewett et al. (12) who suggested athletes can learn new movement patterns and "preprogram" them in order to execute safer and more efficient movement patterns. Preprogramming of such movement patterns may be beneficial in decreasing injury risk (12). Hence, the LPHC conditioning program could have had a positive effect on muscle recruitment patterns that allowed the participants to improve their Tuck Jump Assessment scores.

Since proximal stability allows for more efficient movements distally (18), it would seem that the participants who improved in lumbopelvic hip activation would also improve in landing techniques. So, whether the improvement was a result of the LPHC conditioning program or not, the participants demonstrated beneficial improvements that could contribute to improved neuromuscular efficiency (24).

CONCLUSION

In conclusion, the fact that all participants were able to improve their Tuck Jump Assessment scores is both statistically and clinically significant. Most participants were able to improve on their neuromuscular efficiency as evident by their corrected asymmetries during take-off, flight, and landing phases of the tuck jump. Such improvements could be the result of correcting neuromuscular deficits that may be indicative of increased dynamic knee joint control (7).

REFERENCES

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(a) Katie Roling MS, ATC, (b) Gretchen Oliver PhD, FACSM, ATC, (c) Stephen Dittmore PhD, & (c) Merry Moiseichik, Re.D., J.D. (a) Assistant Athletic Trainer, University of Arkansas, Fayetteville, AR. (b) Sport Biomechanics Group, University of Arkansas, Fayetteville, AR. (c) Recreation and Sport Management, University of Arkansas, Fayetteville, AR.

AUTHOR CORRESPONDENCE:

Gretchen Oliver

326b HPER 1

University of Arkansas

Fayetteville, AR 72701

phone: 479-575-4670;

fax: 479-575-5778;

e-mail: goliver@uark.edu
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Author:Roling, Katie; Oliver, Gretchen; Dittmore, Stephen; Moiseichik, Merry
Publication:Clinical Kinesiology: Journal of the American Kinesiotherapy Association
Article Type:Report
Geographic Code:1USA
Date:Mar 22, 2012
Words:2778
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