IJSPT
ORIGINAL RESEARCH
BILATERAL DIFFERENCES IN THE UPPER QUARTER FUNCTION OF HIGH SCHOOL AGED BASEBALL AND SOFTBALL PLAYERS Robert J. Butler, DPT, PhD1,2,7 Heather S. Myers, PT, LAT, ATC2 Douglass Black DPT, LAT, ATC3 Kyle B. Kiesel PT, PhD, ATC4,5 Phillip J. Plisky, PT, DSc, ATC4,5 Claude T. Moorman 3rd, MD6 Robin M. Queen, PhD7
ABSTRACT Purpose/Background: The Upper Quarter Y Balance Test (YBT-UQ) was developed as a way to identify upper extremity and trunk mobility in the open kinetic chain in the reaching limb as well as midrange limitations and asymmetries of upper extremity and core stability in the closed kinetic chain on the stabilizing limb. Performance on the YBT-UQ is similar between genders and between limbs; however, this has not been examined in athletes who participate in sports that result in upper extremity asymmetries. The primary purpose of this study is to determine if differences exist between the throwing vs. non-throwing sides in high-school baseball and softball athletes on the YBT-UQ. Methods: In order to complete this forty-eight male high school baseball players and seventeen female high school softball players were tested on the YBT-UQ. Reach distances were normalized to arm length (% AL). Comparisons were made between the throwing (T) and non-throwing (NT) arm for each direction as well as the composite score. Results: No significant differences were observed between the T and NT arm for the medial (NT: 98.4 ± 8.6 %AL, T: 99.1 ± 8.6 %AL, p=0.42), inferolateral (NT: 90.8 ± 11.8 %AL, T: 90.3 ± 11.5 %AL, p =0.61), superolateral (NT: 70.6 ± 10.9 %AL, T: 70.4 ± 11.1 % AL, p=0.91) reaches, or the composite score (NT: 87.2 ± 8.9 % AL, T: 86.6 ± 8.1 %AL, p=0.72). Similarly, no differences were observed between the male baseball and female softball players (p=0.30-0.90). Conclusions: Based on these findings, it was concluded that there was no difference in performance on the YBT-UQ between throwing and non-throwing limbs in high school baseball and softball players. Level of Evidence: 3 Key Words: Functional testing, movement, screening, stabilization
1
Doctor Division of Physical Therapy, Duke University, Durham, NC 2 Duke Health Systems Physical Therapy Sports Medicine Division, Durham, NC 3 Katterbach US Army Health Clinic, Katterbach, Bavaria, Germany 4 Department of Physical Therapy, University of Evansville, Evansville, IN 5 ProRehab PC, Evansville, IN 6 Department of Orthopaedics, Division of Sports Medicine, Duke University, Durham, NC 7 Department of Orthopaedics, Michael W. Krzyzewski Human Performance Research Laboratory, Duke University, Durham, NC Disclaimer: The view(s) expressed herein are those of the author(s) and do not reflect the official policy or position of the U.S. Army Public Health Command, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, Department of Defense, or the U.S. Government.
CORRESPONDING AUTHOR Robert J. Butler, PT, PhD Doctor of Physical Therapy Division Duke University DUMC 104002 Durham, NC 27705 Phone: 919.681.7225 Fax: 919.684.1846 E-mail: [email protected]
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 518
INTRODUCTION Shoulder injuries have been estimated to occur at a rate of 2.27 per 10000 to athlete exposures across high school sports.1 High school baseball and softball athletes exhibited some of the highest injury rates (4.5 per 1000 athlete exposures) with the majority of these injuries being overuse in nature.1,2 In high school baseball players, the throwing shoulder is the most common site of injury with a rate of 17%. 3 Pitching accounts for 13% of the injuries in this group.3 These injuries have been associated with elevated pitch counts and limited range of motion in the shoulder complex.4-6 During the rehabilitation of these injuries it is suggested that the injured tissues are progressively loaded while integrating in local joint specific rehabilitation components with body region movements, core stabilizing exercises/activities, and eventually, functional patterns.7 The role of anatomical variation of the humerus on normal arthrokinematic changes and it’s relationship to shoulder biomechanics has been extensively reported upon in the literature, however there is less reported on basic closed kinetic chain tests of the upper extremity that may have relevance in progressing a patient during rehabilitation who participates in throwing sports.8-21 There are currently few tests that assess closed chain upper quarter function, as opposed to sports specific tests, and only one prior study has examined throwing athletes. The primary non-sport specific tests of basic closed chain upper extremity function are the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), the One-arm Hop Test, and the Upper Quarter Y Balance test (YBT-UQ).22-24 The CKCUEST scores how often an individual can tap the floor past the contralateral hand while maintaining an upright pushup position with their feet and stabilizing hand in contact with the ground while keeping their hands 36 inches apart. In comparison, the One-arm Hop test measures a more powerful movement by recording how long it takes an individual to hop with their hand onto a 10.2 cm step 5 times from a 3-point plank position (contralateral hand placed behind back). Finally, the YBT-UQ examines how far an individual can reach with one hand in the medial, inferolateral and superolateral directions while maintaining a 3point plank position on the opposite hand. Isolating unilateral closed chain function may be beneficial
in identifying unilateral upper quarter performance limitations in order to optimize intervention strategies during rehabilitation of athletes who participate in movement activities where left and right upper extremities serve different roles. Based on expected performance requirements alone, it is likely that a continuum of testing exists that would suggest examining basic stability with the CKCUEST prior to testing a relatively low speed closed kinetic chain task (YBT-UQ) before finally examining a more powerful closed kinetic chain task (One Arm Hop). Utilization of the YBT-UQ may have a broader application in the adolescent and youth setting due to the reduced need of upper quarter power to perform the test. Research on all of the aforementioned tests has suggested that performance does not differentiate between sides; however, the subjects during the study did not participate in sports that result in the large upper extremity asymmetries associated with throwing activities.22,24,25 Reliability on all of the aforementioned tests has been established, however, the inherent validity of these tests is still being established. The primary benefit of these data is to provide an understanding of normal asymmetry on tests of upper quarter function, however, none of the aforementioned studies have examined a cohort that participates in activities that promote upper quarter asymmetry, such as baseball and softball, thus research in this area is beneficial. It may be that these glenohumeral adaptations associated with participating in baseball and softball may bias performance on a unilateral basic test of shoulder complex closed chain function. Previous research on upper extremity symmetry supports the concept of side-to-side differences, however, to date little is known about bilateral differences in scores of basic closed-chain shoulder function in baseball and softball athletes. As a result, the primary purpose of this study is to determine if differences exist between the throwing vs. non-throwing sides in high-school baseball and softball athletes on the YBT-UQ. A second purpose of this study is to examine performance differences between male baseball and female softball athletes scores of the YBT-UQ. Based on previous research it is not expected that differences will exist between throwing and nonthrowing sides or across genders.24,25
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 519
METHODS Sample size estimates for the current study were developed by using an α = 0.05, β = 0.20 and a meaningful difference of 10% using previously published work.24 Sample size estimates across the multiple reach directions were calculated manually and revealed that 2842 subjects would be needed to adequately power the study. As a result the research team aimed to obtain data from 50 baseball and softball players in order to count for potential dropout. Athletes at two high schools completed the testing as part of their standard pre-participation physical testing (n = 48, 15 pitchers, age: 15.8 +/- 1.2 years) and softball (n = 17, 4 pitchers, age: 15.2 +/- 1.1 years). Any athlete who was currently painful (has pain but was participating in normal training), exhibited pain during the testing, or was currently injured (currently not participating do to injury) was excluded from the study. All other athletes who were currently participating in full team activities were included in the study. The data were entered into a centralized database from which de-identified data were extracted and analyzed. The research protocol was approved by the institutional review board prior to data analysis. Forty-eight high school baseball players and seventeen high school softball players comprised the final sample, upon whom testing was performed during pre-season physicals. The average age of the baseball players was 15.8 +/- 1.2 years and the average age of the softball players was 15.1 +/- 1.1 years. The average upper limb length of the athletes was 90.8 +/- 4.0 cm for the baseball players and 83.7 +/- 4.2 cm for the softball players. Procedures The YBT-UQ test was utilized in order to examine upper quarter closed chain function in the high school baseball and softball players. The YBT-UQ has previously been established as a reliable functional test of the upper quarter and it has been determined that gender or bilateral differences do not exist in an active adult population.24,25 Previous research on the YBT-UQ has suggested that performance on the test exhibits moderate correlation with established shoulder and core stability measures.25 Reliability measures for the research team were established across the testers in order to maximize testing validity (Inter-rater ICC: 0.99-1.00, Inter-session ICC: 0.92-0.95). Prior to the testing, the upper quarter limb length of each athlete
was measured with the athlete standing with their feet together and their shoulder in 90 degrees of abduction in the frontal plane per protocol. In this position, a cloth tape measure was used to determine the distance (cm) from the spinous process of the 7th cervical vertebrae to the tip of the right middle finger. The YBT-UQ examines the ability of an individual to perform a unilateral activity while maintaining a three-point plank position (one hand and two feet in contact with the ground) with the feet shoulder width apart. During the test, the athlete reaches in the three reach directions (medial, inferolateral, and superolateral [cm]) in a systematic order. Each trial of the YBT-UQ consisted of the athlete reaching in the three reach directions (cm) then subsequently returning to the starting position in a controlled manner (Figure 1). In order for the trial to be acceptable the following criteria had to be maintained: 1) three points of contact had to be maintained between the floor and the hand and feet, 2) the athlete could not use momentum to move the reach box (i.e. push the box), 3) the athlete could not let the reach hand touch the ground during the trial, 4) the athlete could not use the top of the reach box or the testing equipment to help stabilize their body. In order to orient the athlete to the testing procedure, two practice trials were completed on the right side followed by two practice trials on the left side. The tested side was named based on which hand was providing support during the trial. After the practice trials were completed three performance trials were completed for each side, right followed by left. All of the athletes were asked if pain was present during the practice and performance trials. A Y Balance Test Kit (Move2Perform, Evansville, IN) and the YBT-UQ protocol was used during the testing sessions.24 The primary variables of interest for the study were the maximum reach in the medial, superolateral, and inferolateral directions for the throwing and the non-throwing sides as well as the symmetry between the throwing and non-throwing sides for each independent reach direction. In order to complete this analysis the maximum score for each reach direction was extracted to represent the end range of each individual’s performance. The average maximum normalized reach across the three directions was calculated for each side in order to record a composite score for each subject.
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 520
for each of the independent reach directions. Meanwhile, the gender differences were analyzed using an independent samples t-test. All statistically significant differences were identified at p
ORIGINAL RESEARCH
BILATERAL DIFFERENCES IN THE UPPER QUARTER FUNCTION OF HIGH SCHOOL AGED BASEBALL AND SOFTBALL PLAYERS Robert J. Butler, DPT, PhD1,2,7 Heather S. Myers, PT, LAT, ATC2 Douglass Black DPT, LAT, ATC3 Kyle B. Kiesel PT, PhD, ATC4,5 Phillip J. Plisky, PT, DSc, ATC4,5 Claude T. Moorman 3rd, MD6 Robin M. Queen, PhD7
ABSTRACT Purpose/Background: The Upper Quarter Y Balance Test (YBT-UQ) was developed as a way to identify upper extremity and trunk mobility in the open kinetic chain in the reaching limb as well as midrange limitations and asymmetries of upper extremity and core stability in the closed kinetic chain on the stabilizing limb. Performance on the YBT-UQ is similar between genders and between limbs; however, this has not been examined in athletes who participate in sports that result in upper extremity asymmetries. The primary purpose of this study is to determine if differences exist between the throwing vs. non-throwing sides in high-school baseball and softball athletes on the YBT-UQ. Methods: In order to complete this forty-eight male high school baseball players and seventeen female high school softball players were tested on the YBT-UQ. Reach distances were normalized to arm length (% AL). Comparisons were made between the throwing (T) and non-throwing (NT) arm for each direction as well as the composite score. Results: No significant differences were observed between the T and NT arm for the medial (NT: 98.4 ± 8.6 %AL, T: 99.1 ± 8.6 %AL, p=0.42), inferolateral (NT: 90.8 ± 11.8 %AL, T: 90.3 ± 11.5 %AL, p =0.61), superolateral (NT: 70.6 ± 10.9 %AL, T: 70.4 ± 11.1 % AL, p=0.91) reaches, or the composite score (NT: 87.2 ± 8.9 % AL, T: 86.6 ± 8.1 %AL, p=0.72). Similarly, no differences were observed between the male baseball and female softball players (p=0.30-0.90). Conclusions: Based on these findings, it was concluded that there was no difference in performance on the YBT-UQ between throwing and non-throwing limbs in high school baseball and softball players. Level of Evidence: 3 Key Words: Functional testing, movement, screening, stabilization
1
Doctor Division of Physical Therapy, Duke University, Durham, NC 2 Duke Health Systems Physical Therapy Sports Medicine Division, Durham, NC 3 Katterbach US Army Health Clinic, Katterbach, Bavaria, Germany 4 Department of Physical Therapy, University of Evansville, Evansville, IN 5 ProRehab PC, Evansville, IN 6 Department of Orthopaedics, Division of Sports Medicine, Duke University, Durham, NC 7 Department of Orthopaedics, Michael W. Krzyzewski Human Performance Research Laboratory, Duke University, Durham, NC Disclaimer: The view(s) expressed herein are those of the author(s) and do not reflect the official policy or position of the U.S. Army Public Health Command, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, Department of Defense, or the U.S. Government.
CORRESPONDING AUTHOR Robert J. Butler, PT, PhD Doctor of Physical Therapy Division Duke University DUMC 104002 Durham, NC 27705 Phone: 919.681.7225 Fax: 919.684.1846 E-mail: [email protected]
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 518
INTRODUCTION Shoulder injuries have been estimated to occur at a rate of 2.27 per 10000 to athlete exposures across high school sports.1 High school baseball and softball athletes exhibited some of the highest injury rates (4.5 per 1000 athlete exposures) with the majority of these injuries being overuse in nature.1,2 In high school baseball players, the throwing shoulder is the most common site of injury with a rate of 17%. 3 Pitching accounts for 13% of the injuries in this group.3 These injuries have been associated with elevated pitch counts and limited range of motion in the shoulder complex.4-6 During the rehabilitation of these injuries it is suggested that the injured tissues are progressively loaded while integrating in local joint specific rehabilitation components with body region movements, core stabilizing exercises/activities, and eventually, functional patterns.7 The role of anatomical variation of the humerus on normal arthrokinematic changes and it’s relationship to shoulder biomechanics has been extensively reported upon in the literature, however there is less reported on basic closed kinetic chain tests of the upper extremity that may have relevance in progressing a patient during rehabilitation who participates in throwing sports.8-21 There are currently few tests that assess closed chain upper quarter function, as opposed to sports specific tests, and only one prior study has examined throwing athletes. The primary non-sport specific tests of basic closed chain upper extremity function are the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), the One-arm Hop Test, and the Upper Quarter Y Balance test (YBT-UQ).22-24 The CKCUEST scores how often an individual can tap the floor past the contralateral hand while maintaining an upright pushup position with their feet and stabilizing hand in contact with the ground while keeping their hands 36 inches apart. In comparison, the One-arm Hop test measures a more powerful movement by recording how long it takes an individual to hop with their hand onto a 10.2 cm step 5 times from a 3-point plank position (contralateral hand placed behind back). Finally, the YBT-UQ examines how far an individual can reach with one hand in the medial, inferolateral and superolateral directions while maintaining a 3point plank position on the opposite hand. Isolating unilateral closed chain function may be beneficial
in identifying unilateral upper quarter performance limitations in order to optimize intervention strategies during rehabilitation of athletes who participate in movement activities where left and right upper extremities serve different roles. Based on expected performance requirements alone, it is likely that a continuum of testing exists that would suggest examining basic stability with the CKCUEST prior to testing a relatively low speed closed kinetic chain task (YBT-UQ) before finally examining a more powerful closed kinetic chain task (One Arm Hop). Utilization of the YBT-UQ may have a broader application in the adolescent and youth setting due to the reduced need of upper quarter power to perform the test. Research on all of the aforementioned tests has suggested that performance does not differentiate between sides; however, the subjects during the study did not participate in sports that result in the large upper extremity asymmetries associated with throwing activities.22,24,25 Reliability on all of the aforementioned tests has been established, however, the inherent validity of these tests is still being established. The primary benefit of these data is to provide an understanding of normal asymmetry on tests of upper quarter function, however, none of the aforementioned studies have examined a cohort that participates in activities that promote upper quarter asymmetry, such as baseball and softball, thus research in this area is beneficial. It may be that these glenohumeral adaptations associated with participating in baseball and softball may bias performance on a unilateral basic test of shoulder complex closed chain function. Previous research on upper extremity symmetry supports the concept of side-to-side differences, however, to date little is known about bilateral differences in scores of basic closed-chain shoulder function in baseball and softball athletes. As a result, the primary purpose of this study is to determine if differences exist between the throwing vs. non-throwing sides in high-school baseball and softball athletes on the YBT-UQ. A second purpose of this study is to examine performance differences between male baseball and female softball athletes scores of the YBT-UQ. Based on previous research it is not expected that differences will exist between throwing and nonthrowing sides or across genders.24,25
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 519
METHODS Sample size estimates for the current study were developed by using an α = 0.05, β = 0.20 and a meaningful difference of 10% using previously published work.24 Sample size estimates across the multiple reach directions were calculated manually and revealed that 2842 subjects would be needed to adequately power the study. As a result the research team aimed to obtain data from 50 baseball and softball players in order to count for potential dropout. Athletes at two high schools completed the testing as part of their standard pre-participation physical testing (n = 48, 15 pitchers, age: 15.8 +/- 1.2 years) and softball (n = 17, 4 pitchers, age: 15.2 +/- 1.1 years). Any athlete who was currently painful (has pain but was participating in normal training), exhibited pain during the testing, or was currently injured (currently not participating do to injury) was excluded from the study. All other athletes who were currently participating in full team activities were included in the study. The data were entered into a centralized database from which de-identified data were extracted and analyzed. The research protocol was approved by the institutional review board prior to data analysis. Forty-eight high school baseball players and seventeen high school softball players comprised the final sample, upon whom testing was performed during pre-season physicals. The average age of the baseball players was 15.8 +/- 1.2 years and the average age of the softball players was 15.1 +/- 1.1 years. The average upper limb length of the athletes was 90.8 +/- 4.0 cm for the baseball players and 83.7 +/- 4.2 cm for the softball players. Procedures The YBT-UQ test was utilized in order to examine upper quarter closed chain function in the high school baseball and softball players. The YBT-UQ has previously been established as a reliable functional test of the upper quarter and it has been determined that gender or bilateral differences do not exist in an active adult population.24,25 Previous research on the YBT-UQ has suggested that performance on the test exhibits moderate correlation with established shoulder and core stability measures.25 Reliability measures for the research team were established across the testers in order to maximize testing validity (Inter-rater ICC: 0.99-1.00, Inter-session ICC: 0.92-0.95). Prior to the testing, the upper quarter limb length of each athlete
was measured with the athlete standing with their feet together and their shoulder in 90 degrees of abduction in the frontal plane per protocol. In this position, a cloth tape measure was used to determine the distance (cm) from the spinous process of the 7th cervical vertebrae to the tip of the right middle finger. The YBT-UQ examines the ability of an individual to perform a unilateral activity while maintaining a three-point plank position (one hand and two feet in contact with the ground) with the feet shoulder width apart. During the test, the athlete reaches in the three reach directions (medial, inferolateral, and superolateral [cm]) in a systematic order. Each trial of the YBT-UQ consisted of the athlete reaching in the three reach directions (cm) then subsequently returning to the starting position in a controlled manner (Figure 1). In order for the trial to be acceptable the following criteria had to be maintained: 1) three points of contact had to be maintained between the floor and the hand and feet, 2) the athlete could not use momentum to move the reach box (i.e. push the box), 3) the athlete could not let the reach hand touch the ground during the trial, 4) the athlete could not use the top of the reach box or the testing equipment to help stabilize their body. In order to orient the athlete to the testing procedure, two practice trials were completed on the right side followed by two practice trials on the left side. The tested side was named based on which hand was providing support during the trial. After the practice trials were completed three performance trials were completed for each side, right followed by left. All of the athletes were asked if pain was present during the practice and performance trials. A Y Balance Test Kit (Move2Perform, Evansville, IN) and the YBT-UQ protocol was used during the testing sessions.24 The primary variables of interest for the study were the maximum reach in the medial, superolateral, and inferolateral directions for the throwing and the non-throwing sides as well as the symmetry between the throwing and non-throwing sides for each independent reach direction. In order to complete this analysis the maximum score for each reach direction was extracted to represent the end range of each individual’s performance. The average maximum normalized reach across the three directions was calculated for each side in order to record a composite score for each subject.
The International Journal of Sports Physical Therapy | Volume 9, Number 4 | August 2014 | Page 520
for each of the independent reach directions. Meanwhile, the gender differences were analyzed using an independent samples t-test. All statistically significant differences were identified at p
