Factors such as range of motion (ROM),1 strength,2 scapular kinematics,3–5 joint laxity, and reposition sense6 in the shoulders of baseball players have been extensively examined. These studies have advanced the field's understanding of injury prevention and management of high-level throwing athletes. Although the shoulder complex receives much attention in baseball medicine literature, these athletes must rely on the entire kinetic chain to effectively throw a baseball. This reality has stimulated the study of numerous links in the kinetic chain, including the hip7–10 and trunk,11–16 regarding their roles in safe and efficient throwing. Like functional movement in other body regions, movement sequencing and force production of throwing a baseball rely heavily on the sensorimotor ability of the spine.16 This includes activation and control of dynamic restraints throughout the vertebral column, particularly in the thoracolumbar region.16
For individuals participating in sports like baseball where the spine undergoes repetitive and forceful movements, sensorimotor errors could result in the spine being malpositioned during movement and subsequently development of injury.17 Altered scapular kinematics, limited glenohumeral abduction ROM, and insufficient muscle force production can be consequences of malpositioning in the thoracolumbar spine.18 Thus, improper spinal positioning underlines several kinetic and kinematic variables leading to upper extremity dysfunction and demands further study.
The positioning of the trunk is also essential for optimal performance in baseball. Previous authors have examined positioning errors of the trunk and demonstrated that, while throwing, alterations in the athlete's lateral trunk lean,14 sagittal plane trunk tilt,15 and trunk rotation sequencing13 can affect ball velocity14,15 and forces at the elbow14,15 and shoulder.13,14 Thus, the relevance of the trunk's function in safe and effective throwing is clear and its sensorimotor ability should be considered.18
Previous literature has demonstrated the shoulders of symptomatic and asymptomatic individuals, particularly those whose shoulders undergo high stress demands from sport, have altered sensorimotor control.19–23 These findings support the hypothesis that baseball players may also have compromised sensorimotor control in their thoracolumbar spine because it contributes to the generation, transference, and sequencing of the throwing motion.13,16 Because of the high stress demands incurred by the thoracolumbar region while training and competing in baseball, its sensorimotor ability should be examined. To date, no studies have examined and documented normative ranges of position sense in the thoracolumbar spine among baseball players.
Therefore, the aims of this study were to (1) examine active repositioning error (ARE) of the thoracolumbar spine among collegiate baseball players, (2) compare ARE between pitchers and position players, and (3) compare thoracolumbar rotation and side-bending ARE bilaterally.
This study used a cross-sectional design. Two groups composed of asymptomatic collegiate pitchers and position players participated. Dependent variables included participants' ARE scores for thoracolumbar rotation toward the throwing arm side (TLRthrowing), thoracolumbar rotation toward the non-throwing arm side (TLRnon-throwing), thoracolumbar flexion (TLF), thoracolumbar side-bending toward the throwing arm side (Sidebendthrowing), and thoracolumbar side-bending toward the non-throwing arm side (Sidebendnon-throwing).
ARE scores for each variable conceptually represented participants' absolute error in their ability to reposition their thoracolumbar spine to the target position. An ARE score of 0° would indicate a participant repositioned their spine with 100% accuracy. However, an ARE score of 10° would indicate participants inaccurately repositioned their spine (in relation to the target position) by an average of 10°. In the current study, the target position was calculated as the halfway point of the participants' full baseline ROM in a given direction. ARE scores were calculated as the difference between the patient's target position (eg, the halfway point of his full baseline ROM in a given direction) and the mean of their three attempts (trials) to reposition themselves to that target position.
Asymptomatic National Collegiate Athletic Association (NCAA) Division I collegiate male baseball pitchers (n = 17, age = 20.2 ± 1.3 years, height = 188.7 ± 6.9 cm, mass = 95.5 ± 7.7 kg) and position players (n = 15, age = 20.5 ± 1.4 years, height = 185.4 ± 4.6 cm, mass = 90.2 ± 4.5 kg) volunteered to participate in this study.
Participant exclusion criteria were a history of spine or upper limb injury within the past 6 months or a history of surgery to the spine or upper extremity. Participants were also excluded if they were medically diagnosed as having balance disorders, neurologic disorders, or spinal abnormalities such as scoliosis or Scheuermann's disease.
All participants signed an institutional review board approved informed consent form prior to participation in the study. All participants completed one testing session in the Illinois State University sports medicine clinic. The same two examiners (JW and HH) measured the dependent variables for all participants and were blinded to participants' group membership.
The methodology used in this study was adapted from previous literature that assessed thoracolumbar spine motion in the sagittal,24,25 frontal,26 and transverse12 planes. All instruments and methods of measurement were chosen for their clinical utility. Intra-rater reliability coefficients, standard error of measurement (SEM), and minimal detectable change based on 95% confidence (MDC 95%) for measuring reposition sense in TLRthrowing, TLRnon-throwing, TLF, Sidebendthrowing, and Sidebendnon-throwing were .87 (SEM = 2.4°, MDC 95% = 6.6°), .76 (SEM = 2.7°, MDC 95% = 7.5°), .83 (SEM = 2.6°, MDC 95% = 7.2°), .87 (SEM = 1.6°, MDC 95% = 4.4°), and .85 (SEM = 1.5°, MDC 95% = 4.2°), respectively. The reliability coefficients in this study were consistent with similar measures used in previous examinations of the thoracolumbar spine in baseball players.12
All participants removed their shirts prior to testing, enabling examiners to palpate the C7 and S2 spinous processes. These landmarks were marked with a pen to standardize the placement of the bubble inclinometers. Prior to all measurements, participants were blindfolded to eliminate visual input assisting their reposition sense.24 Participants also wore noise-cancelling headphones during the three measurement trials for each dependent variable. The headphones prevented participants hearing the researchers communicate their bubble inclinometer readings to each other. This eliminated participants experiencing a training effect and adjusting subsequent attempts to move toward target ranges. Both examiners observed the participants for compensatory motions (eg, altered positioning of their lower limbs or trunk) during all measurements. If a compensatory motion occurred, the trial was stopped and performed again. A total of three trials were performed for each dependent variable.
Measuring ARE in Thoracolumbar Flexion. T.his measurement began with the participants in a seated position on top of a modified stool. The stool was modified, similar to that in a previous study,24 by fixing a flat wooden board to the top and rear portion of the stool's surface. The added board served as a standard reference point for positioning the participants' sacral bones and limited the region's contribution to movement of the thoracolumbar spine.
After being positioned properly on the stool, participants were instructed to assume an upright sitting position using the following standard description: “Please sit up straight with your rear-end maintaining contact with the stool and board. Keep your feet shoulder width apart and flat on the floor and rest your fingertips atop your shoulders.” When in this position, the bubble inclinometer (Fabrication Enterprise, Inc) was positioned in the sagittal plane on the pre-marked spinous processes and calibrated to zero to begin the measurement. Next, the participants were instructed to flex their trunk forward “as far as you can go.” Then the inclinometer was used to determine the full range of trunk flexion. After documenting the participants' full ROM, they underwent active-assisted range of motion (AAROM) to the target position, defined as 50% of their full ROM. Participants were instructed to remember the target position because they would be asked to reposition into the target position 10 seconds later.
After the 10-second rest period, the participants were instructed to reassume the upright sitting position, the bubble inclinometer was repositioned and calibrated to zero on their backs, and they were instructed to actively reposition into the previously identified target position (Figure 1A). They were given a 10-second rest period following this first trial and the process was repeated for a total of three trials.
Measuring thoracolumbar active repositioning error for (A) flexion, (B) side-bending, and (C) rotation.
Measuring ARE in Thoracolumbar Side-bending. Participants were seated on top of the modified stool with their feet shoulder width apart. They were instructed to assume the upright sitting position with their fingertips positioned on top of their ipsilateral shoulders. The bubble inclinometer was then positioned on the C7 spinous process in the frontal plane. The inclinometer was calibrated to zero and participants were instructed to “side-bend your trunk as far as you can go, and then return to your upright sitting position.” This total range of thoracolumbar side-bending was recorded. Participants then underwent AAROM to the target position of frontal plane motion, defined as 50% of their total frontal plane ROM. Participants were instructed to remember that target position so they could reposition into it 10 seconds later.
After resting for 10 seconds while remaining seated on the stool, the participants were instructed to reassume the upright sitting position, where the bubble inclinometer was repositioned on the C7 spinous process and calibrated to zero. Participants were then asked to actively reposition into the target position and this reposition measurement was recorded (Figure 1B). Participants were given a 10-second rest period following this first trial and the process was repeated for a total of three trials. Examiners observed the participants for compensatory motions (eg, altered positioning of their lower limbs or trunk) during the measurement. ARE into thoracolumbar side-bending was measured bilaterally toward the throwing and non-throwing arm sides on all participants.
Measuring ARE into Thoracolumbar Rotation. Participants were positioned standing with their feet shoulder width apart, knees flexed slightly, trunk flexed 90°, and fingertips touching contralateral acromion processes. Then bubble inclinometers were positioned on the C7 and S2 spinous processes and calibrated to zero. The participants were then instructed to “rotate your trunk as far as you can go, then return to your starting position.” This full range of thoracolumbar rotation ROM was recorded. The participants then underwent AAROM to their target position represented by 50% of their full thoracolumbar rotation ROM. Participants were instructed to remember that target position so they could reposition into it after a 10-second rest period.
After the 10-second rest period, participants were instructed to reassume the starting position and the bubble inclinometers were repositioned on their backs and calibrated to zero. The participants were instructed to actively reposition their trunk to the target position and that point was recorded (Figure 1C). They were given a 10-second rest period following the first trial, and the process was repeated for a total of three trials. The participants were observed by both examiners for compensatory motions during the measurement. Transverse plane ARE was measured bilaterally toward the throwing and non-throwing arm sides on all participants.
Data were analyzed using SPSS software (version 24; IBM Corporation). A Kolmogorov-Smirnov test was used to test for normality. Independent t tests were used to compare mean ARE scores in each plane of thoracolumbar motion (TLRthrowing, TLRnon-throwing, TLF, Sidebendthrowing, and Sidebendnon-throwing) between groups and to compare bilateral TLR and side-bending ARE scores within the groups (pitchers and position players). P values were set a priori at .05.
Results from the preliminary Kolmogorov-Smirnov test demonstrated normality for all variables where P values of TLRthrowing, TLRnon-throwing, TLF, Sidebendthrowing, and Sidebendnon-throwing were .19, .20, .20, .20, and .20, respectively. The normality assessment confirmed use of parametric statistical procedures.
Descriptive statistics for ARE scores into TLR, TLF, and side-bending between the groups are presented in Table 1.
Descriptive Statistics for Thoracolumbar ARE Scores
Results of independent t tests comparing ARE between pitchers and position players are listed in Table 2. There were no significant differences between the groups' ARE into TLRthrowing (t30 = 1.3, P = .21), TLRnon-throwing (t30 = .60, P = .56), TLF (t30 = −1.1, P = .29), Sidebendthrowing (t30 = −.72, P = .48), and Sidebendnon-throwing (t30 = −.14, P = .89).
ARE Between Pitchers and Position Players
Table 3 provides results of independent t tests comparing bilateral ARE within groups. There were no significant differences between the pitchers' ARE into TLRthrowing and TLRnon-throwing (t32 = .13, P = .90) or Sidebendthrowing and Sidebendnon-throwing (t32 = .13, P = .90). Position players also demonstrated no significant differences in ARE between TLRthrowing and TLRnon-throwing (t28 = −.65, P = .52) or Sidebendthrowing and Sidebendnon-throwing (t28 = −.07, P = .95).
Bilateral Comparison of ARE Within Pitchers and Position Players
Sensorimotor function has been extensively examined in the glenohumeral joint among baseball players,19,20,27,28 but this topic is absent in the literature for the thoracolumbar spine. Although sensorimotor errors in the spine could play a significant role in the development of injury,17 proper control may support safer and more optimal baseball performance. Thus, ARE in the thoracolumbar region should become a component in clinicians' physical examinations of symptomatic and asymptomatic athletes.
This study is the first of its kind to (1) report a descriptive profile of ARE in the thoracolumbar spines of baseball players; (2) compare ARE between pitchers and position players; and (3) bilaterally compare thoracolumbar rotation and side-bending ARE. The following sections will interpret our findings with regard to these aims.
Aim 1: Descriptive Profile of ARE in the Thoracolumbar Spine
By observing the widths of the confidence intervals in Table 1, a clinician working with an asymptomatic collegiate baseball player can be 95% confident that the athlete will accurately reposition his thoracolumbar spine to within approximately 4°, 5°, and 7.5° of the mean thoracolumbar rotation, flexion, and side-bending ARE scores reported in this study. These findings provide clinicians working in baseball medicine with a normative data profile to consider when estimating, measuring, and interpreting the thoracolumbar position sense of their athletes.
These confidence intervals also serve as measurements of precision and offer clinical meaningfulness to practitioners. Although a narrower range between the lower- and upper boundaries of a confidence interval represents more precision, a wider range indicates less precision. In the current study, the ranges between the lower and upper-boundaries of confidence intervals in the transverse, sagittal, and frontal planes ranged from approximately 4° to 7.5°. Interpreting the width of these confidence intervals against previous studies is difficult due to a lack of consistency in methods. For example, confidence intervals in previous studies have demonstrated widths as low as 0.60°29 and 0.68°.24 Previous studies have used different participant demographics, only examined sagittal plane movement of the spine, and used higher fidelity instrumentation that was laboratory based. We contend that these differences, and our smaller sample size, underlie the wider confidence intervals in the current study. Although we acknowledge making population estimates from the findings of the current study may be less precise than previous studies, our measurement procedure and instrumentation can be employed in a clinical setting with little economic and physical burden to the clinician and patient.
We maintain that the confidence intervals in the current study offer clinical meaning to readers by providing clinicians estimates of their patients' thoracolumbar ARE scores, if measured using the same technique. Additionally, the confidence intervals illustrate a need for continued study of the measurement technique.
Normal ARE in the transverse plane for the lumbar spine has been reported as 1.7°.30 In the current study, pitchers' ARE into TLRthrowing (.53 ± 5.8°) and TLRnon-throwing (.26 ± 6.1°) and position players' ARE into TLRthrowing (−2.0 ± 5.4°) and TLRnon-throwing (.87 ± 4.4°) were either much lower or near the 1.7° previously observed among lay people.30 Such findings demonstrate the pitchers and position players in the current study having consistent reposition acuity compared to the non-athletes studied in previous work.
Previously reported ARE into trunk flexion ranges from 1.26° to 6.53°.24,31–34 In comparison, findings in the current study demonstrated that pitchers had “normal” (5.4 ± 8.5°) ARE into flexion, whereas position players' (8.4 ± 7.0°) mean flexion ARE was greater than that observed among non-athletes.
Normal ARE in the frontal plane has ranged from 1.8° to 2.5°.30,31,35 Pitchers' ARE into Sidebendthrowing (.59 ± 3.5°) and Sidebendnon-throwing (.26 ± 4.3°) and position players' ARE into Sidebendthrowing (.37 ± 4.0°) and Sidebendnon-throwing (.47° ± 4.0) were much lower than the lower range observed among non-athletes.30,31,35
We speculate the variability between previous findings and ours are due to differences in participant demographics, measurement procedures, and instrumentation. Because the current study included a group of NCAA Division I baseball players, our participants were much different than those in previous studies, where the participants' age ranged from 7 to 52 years old, participants were non-athletes, and male and female participants were included.24,31,35 Additionally, previous studies used instruments ranging from wooden meter sticks24 to electromagnetic motion capture systems31 to measure repositioning error in the spine, whereas no studies employed the widely used and accessible clinical instrument used in the current study. The differences in participant demographics and methods may contribute to the variation in ARE findings between the current study and others and may make it inappropriate to draw inferences from the differences.
Aim 2: Pitchers Versus Position Players' ARE
Our data showed no statistical difference between pitchers' and position players' ARE scores in thoracolumbar rotation, flexion, and side-bending.
We believe our findings support that participation in different baseball positions has little influence on ARE of the thoracolumbar spine. An accumulation of microtrauma in soft-tissue restraints around a joint and subsequent changes in laxity of those structures tends to desensitize local mechanoreceptors and compromise sensorimotor ability.36 This represents the etiology underlying diminished sensorimotor ability in other body regions like the shoulder,36 and we suspected a similar pathomechanical cycle might occur in the thoracolumbar spine. Despite the thoracic and lumbar spine regions hosting numerous mechanoreceptors and proprioceptive nerve structures,37 our results suggest the function of those structures may not be compromised from the conceivably differing amounts of accumulated microtrauma in and around the spine from training and competing as a pitcher compared to as a position player.
Aim 3: Bilateral Comparison of ARE
Although the motions of throwing are forceful, repetitive, and asymmetrical, the baseball players demonstrated no differences in bilateral position sense in the transverse and frontal planes. This finding supports sensorimotor function in the spine may not be affected by the asymmetrical nature of baseball-related movements.
Instead, we suspect the previously noted pathomechanical cycle typically leading to compromised sensorimotor ability is superseded in these athletes by a high level of training effect on their sensorimotor faculties. In other words, although baseball players might pre-dispose mechanoreceptors in the thoracolumbar region to becoming damaged from the forceful and repetitive sports tasks, their years of ongoing proprioceptive training (eg, being coached and practicing various body mechanics) may contribute to overwhelmingly well integrated somatosensory and neuromuscular abilities resulting in heightened sensorimotor ability in the region. We believe this is possible because it is well accepted in clinical practice and in the literature that proprioceptive faculties are improved through exercise and motor-skill training.38
Like all research, the current study has limitations. Our results are limited to baseball players competing at the NCAA Division I level and should not be generalized to players at different skill levels and other overhead sport populations. We also acknowledge the need for ARE to be examined among larger sample sizes. In addition, we measured ARE during preseason before sanctioned baseball practices and conditioning commenced. The demands of the season and effects after a season may alter ARE. Finally, we employed our method of measuring ARE for its clinical utility. We acknowledge its inability to account for variables like ARE at specific vertebral levels or tension in static and dynamic restraints in and surrounding the thoracolumbar spine.
Future investigations should expand this work by examining ARE throughout different ranges of thoracolumbar ROM. In the current study, we only examined ARE in the participants' mid-ranges (relativized to the individual's full ROM), what we called the target position. Some authors hypothesize position sense is reduced near mid-ranges of joint motion because tension on static and dynamic restraints surrounding the joint are not sufficiently stimulating the mechanoreceptors and proprioceptors in the area.39 By examining ARE at different points throughout ROM, we gain a more comprehensive understanding of the presence and variation of spinal repositioning accuracy. This study would also substantiate the theory of position sense being influenced by changes in tension on static and dynamic soft-tissue restraints surrounding a joint region.23,40
Future studies should also explore ARE among injured baseball athletes. We used asymptomatic athletes with the understanding that sensorimotor alterations have been observed in other areas of the body among healthy participants. We hypothesized the same might have been observed in the spine. Nonetheless, it remains important to examine how various acute and chronic injuries throughout the kinetic chain may influence position sense of the spine.
We also encourage future research to explore how variables including fatigue, skill level, participation throughout and across competitive seasons, and flexibility of different links in the kinetic chain might influence ARE in the thoracolumbar spine.
Implications for Clinical Practice
Previous research has demonstrated a link between deficient sensorimotor function and injury in the shoulders of baseball players.19,21,27,28 These sensorimotor deficits are typically attributed to accumulated microtrauma in the surrounding soft tissues, thereby inhibiting function of the mechanoreceptors and proprioceptors in the area.36 It is well accepted that injury prevention and management demands clinicians' attention to the sensorimotor system because it is responsible for coordinating stable and safe movement throughout the kinetic chain.38 Therefore, having a normative profile of joint position sense acuity can support more advanced examination and assessment practices in sports medicine.
This study is the first to provide a normative profile of joint position sense in the thoracolumbar spine for clinicians to consider when measuring and interpreting sensorimotor function among baseball players. Although our findings demonstrated no differences in ARE between pitchers and position players, nor bilateral differences within the groups, we remain unsure whether other variables commonly experienced by baseball players (ie, training history, fatigue, injury, and movement adaptations) in adjacent joints would influence their position sense acuity. Therefore, we encourage clinicians to consider the normative data profile in this study during their comprehensive physical examinations of asymptomatic baseball players.
- Myers JB, Laudner KG, Pasquale MR, Bradley JP, Lephart SM. Glenohumeral range of motion deficits and posterior shoulder tightness in throwers with pathologic internal impingement. Am J Sports Med. 2006;34(3):385–391. doi:10.1177/0363546505281804 [CrossRef]
- Amin NH, Ryan J, Fening SD, Soloff L, Schickendantz MS, Jones M. The relationship between glenohumeral internal rotational deficits, total range of motion, and shoulder strength in professional baseball pitchers. J Am Acad Orthop Surg. 2015;23(12):789–796. doi:10.5435/JAAOS-D-15-00292 [CrossRef]
- Yu H-D, Park J-Y. Three-dimensional analysis of scapular kinematics during arm elevation in baseball players with scapular dyskinesis: comparison of dominant and non-dominant arms. Br J Sports Med. 2017;51(4):411–412. doi:10.1136/bjsports-2016-097372.323 [CrossRef]
- Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology. Part 1: pathoanatomy and biomechanics. Arthroscopy. 2003;19(4):404–420. doi:10.1053/jars.2003.50128 [CrossRef]
- Laudner KG, Myers JB, Pasquale MR, Bradley JP, Lephart SM. Scapular dysfunction in throwers with pathologic internal impingement. J Orthop Sports Phys Ther. 2006;36(7):485–494. doi:10.2519/jospt.2006.2146 [CrossRef]
- Laudner KG, Meister K, Kajiyama S, Noel B. The relationship between anterior glenohumeral laxity and proprioception in collegiate baseball players. Clin J Sport Med. 2012;22(6):478–482. doi:10.1097/JSM.0b013e31826903f5 [CrossRef]
- Robb AJ, Fleisig G, Wilk K, Macrina L, Bolt B, Pajaczkowski J. Passive ranges of motion of the hips and their relationship with pitching biomechanics and ball velocity in professional baseball pitchers. Am J Sports Med. 2010;38(12):2487–2493. doi:10.1177/0363546510375535 [CrossRef]
- Sauers EL, Huxel Bliven KC, Johnson MP, Falsone S, Walters S. Hip and glenohumeral rotational range of motion in healthy professional baseball pitchers and position players. Am J Sports Med. 2014;42(2):430–436. doi:10.1177/0363546513508537 [CrossRef]
- Laudner K, Wong R, Onuki T, Lynall R, Meister K. The relationship between clinically measured hip rotational motion and shoulder biomechanics during the pitching motion. J Sci Med Sport. 2015;18(5):581–584. doi:10.1016/j.jsams.2014.07.011 [CrossRef]
- Oliver GD, Keeley DW. Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers. J Strength Cond Res. 2010;24(12):3241–3246. doi:10.1519/JSC.0b013e3181cc22de [CrossRef]
- Young JL, Herring SA, Press JM, Casazza BA. The influence of the spine on the shoulder in the throwing athlete. J Back Musculoskeletal Rehabil. 1996;7(1):5–17. doi:10.3233/BMR-1996-7103 [CrossRef]
- Laudner K, Lynall R, Williams JG, Wong R, Onuki T, Meister K. Thoracolumbar range of motion in baseball pitchers and position players. Int J Sports Phys Ther. 2013;8(6):777–783.
- Oyama S, Yu B, Blackburn JT, Padua DA, Li L, Myers JB. Improper trunk rotation sequence is associated with increased maximal shoulder external rotation angle and shoulder joint force in high school baseball pitchers. Am J Sports Med. 2014;42(9):2089–2094. doi:10.1177/0363546514536871 [CrossRef]
- Solomito MJ, Garibay EJ, Woods JR, Õunpuu S, Nissen CW. Lateral trunk lean in pitchers affects both ball velocity and upper extremity joint moments. Am J Sports Med. 2015;43(5):1235–1240. doi:10.1177/0363546515574060 [CrossRef]
- Solomito MJ, Garibay EJ, Nissen CW. Sagittal plane trunk tilt is associated with upper extremity joint moments and ball velocity in collegiate baseball pitchers. Orthop J Sport Med. 2018;6(10): 2325967118800240. doi:10.1177/2325967118800240 [CrossRef]
- Aguinaldo AL, Buttermore J, Chambers H. Effects of upper trunk rotation on shoulder joint torque among baseball pitchers of various levels. J Appl Biomech. 2007;23(1):42–51. doi:10.1123/jab.23.1.42 [CrossRef]
- Fleisig GS, Hsu WK, Fortenbaugh D, Cordover A, Press JM. Trunk axial rotation in baseball pitching and batting. Sport Biomech. 2013; 12(4):324–333. doi:10.1080/14763141.2013.838693 [CrossRef]
- Kebaetse M, McClure P, Pratt NA. Thoracic position effect on shoulder range of motion, strength, and three-dimensional scapular kinematics. Arch Phys Med Rehabil. 1999;80(8):945–950. doi:10.1016/S0003-9993(99)90088-6 [CrossRef]
- Barden JM, Balyk R, Raso VJ, Moreau M, Bagnall K. Dynamic upper limb proprioception in multidirectional shoulder instability. Clin Orthop Relat Res. 2004;420:181–189. doi:10.1097/00003086-200403000-00025 [CrossRef]
- Myers JB, Ju YY, Hwang JH, McMahon PJ, Rodosky MW, Lephart SM. Reflexive muscle activation alterations in shoulders with anterior glenohumeral instability. Am J Sports Med. 2004;32(4):1013–1021. doi:10.1177/0363546503262190 [CrossRef]
- Lephart SM, Warner JJP, Borsa PA, Fu FH. Proprioception of the shoulder joint in healthy, unstable, and surgically repaired shoulders. J Shoulder Elbow Surg. 1994;3(6):371–380. doi:10.1016/S1058-2746(09)80022-0 [CrossRef]
- Dover GC, Kaminski TW, Meister K, Powers ME, Horodyski M. Assessment of shoulder proprioception in the female softball athlete. Am J Sports Med. 2003;31(3):431–437. doi:10.1177/03635465030310031801 [CrossRef]
- Allegrucci M, Whitney SL, Lephart SM, Irrgang JJ, Fu FH. Shoulder kinesthesia in healthy unilateral athletes participating in upper extremity sports. J Orthop Sports Phys Ther. 1995;21(4):220–226. doi:10.2519/jospt.1922.214.171.124 [CrossRef]
- Petersen CM, Zimmermann CL, Cope S, Bulow ME, Ewers-Panveno E. A new measurement method for spine reposition sense. J Neuroeng Rehabil. 2008;5(1):9. doi:10.1186/1743-0003-5-9 [CrossRef]
- Lewis JS, Valentine RE. Clinical measurement of the thoracic kyphosis: a study of the intra-rater reliability in subjects with and without shoulder pain. BMC Musculoskelet Disord. 2010;11(1):39. doi:10.1186/1471-2474-11-39 [CrossRef]
- Starkey C, Brown S. Examination of Orthopedic and Athletic Injuries, 4th ed. F.A. Davis Company; 2015.
- Warner JJP, Lephart S, Fu FH. Role of proprioception in pathoetiology of shoulder instability. Clin Orthop Relat Res. 1996;330:35–39. doi:10.1097/00003086-199609000-00005 [CrossRef]
- Smith RL, Brunolli J. Shoulder kinesthesia after anterior glenohumeral joint dislocation. Phys Ther. 1989;69(2):106–112. doi:10.1093/ptj/69.2.106 [CrossRef]
- Dolan KJ, Green A. Lumbar spine reposition sense: the effect of a ‘slouched’ posture. Man Ther. 2006;11(3):202–207. doi:10.1016/j.math.2006.03.003 [CrossRef]
- Lee AS, Cholewicki J, Reeves NP, Zazulak BT, Mysliwiec LW. Comparison of trunk proprioception between patients with low back pain and healthy controls. Arch Phys Med Rehabil. 2010;91(9):1327–1331. doi:10.1016/j.apmr.2010.06.004 [CrossRef]
- Swinkels A, Dolan P. Regional assessment of joint position sense in the spine. Spine. 1998;23(5):590–597. doi:10.1097/00007632-199803010-00012 [CrossRef]
- Swinkels A, Dolan P. Spinal position sense is independent of the magnitude of movement. Spine. 2000;25(1):98–104. doi:10.1097/00007632-200001010-00017 [CrossRef]
- Gill KP, Callaghan MJ. The measurement of lumbar proprioception in individuals with and without low back pain. Spine. 1998;23(3):371–377. doi:10.1097/00007632-199802010-00017 [CrossRef]
- Koumantakis GA, Winstanley J, Oldham JA. Thoracolumbar proprioception in individuals with and without low back pain: intra-tester reliability, clinical applicability, and validity. J Orthop Sport Phys Ther. 2002;32(7):327–335. doi:10.2519/jospt.2002.32.7.327 [CrossRef]
- Ashton-Miller JA, McGlashen KM, Schultz AB. Trunk positioning accuracy in children 7–18 years old. J Orthop Res. 1992;10(2):217–225. doi:10.1002/jor.1100100209 [CrossRef]
- Tibone JE, Fechter J, Kao JT. Evaluation of a proprioception pathway in patients with stable and unstable shoulders with somatosensory cortical evoked potentials. J Shoulder Elbow Surg. 1997;6(5):440–443. doi:10.1016/S1058-2746(97)70050-8 [CrossRef]
- McLain RF, Pickar JG. Mechanoreceptor endings in human thoracic and lumbar facet joints. Spine. 1998;23(2):168–173. doi:10.1097/00007632-199801150-00004 [CrossRef]
- Röijezon U, Clark NC, Treleaven J. Proprioception in musculo-skeletal rehabilitation. Part 1: basic science and principles of assessment and clinical interventions. Man Ther. 2015;20(3):368–377. doi:10.1016/j.math.2015.01.008 [CrossRef]
- Tripp BL, Uhl TL, Mattacola CG, Srinivasan C, Shapiro R. Functional multijoint position reproduction acuity in overhead-throwing athletes. J Athl Train. 2006;41(2):146–153.
- Janwantanakul P, Magarey ME, Jones MA, Dansie BR. Variation in shoulder position sense at mid and extreme range of motion. Arch Phys Med Rehabil. 2001;82(6):840–844. doi:10.1053/apmr.2001.21865 [CrossRef]
Descriptive Statistics for Thoracolumbar ARE Scoresa
|Parameter||N||Mean ± SD||95% CI|
| Pitchers||17||.53 ± 5.7||−2.2 to 3.3|
| Position players||15||−2.0 ± 5.4||−0.73 to 4.7|
| Pitchers||17||.26 ± 6.1||−2.6 to 3.2|
| Position players||15||−.87 ± 4.4||−1.4 to 3.1|
| Pitchers||17||5.4 ± 8.5||1.4 to 9.4|
| Position players||15||8.4 ± 7.0||4.9 to 11.9|
| Pitchers||17||−.59 ± 3.5||−1.1 to 2.3|
| Position players||15||.37 ± 4.0||−1.7 to 2.4|
| Pitchers||17||.26 ± 4.3||−1.8 to 2.3|
| Position players||15||.47 ± 4.0||−1.6 to 2.5|
ARE Between Pitchers and Position Players
|Direction of Movement||Pitchers' ARE (n = 17)||Position Players' ARE (n = 15)||Difference||t30Value||P|
|TLRThrowing||.53 ± 5.7°||−2.0 ± 5.4°||2.6°||1.3||.21|
|TLRNon-throwing||.26 ± 6.1°||−.87 ± 4.4°||1.1°||.60||.56|
|TLF||5.4 ± 8.5°||8.4 ± 7.0°||−3.0°||−1.1||.29|
|Side-bendingThrowing||−.59 ± 3.5°||.37 ± 4.0°||−.95°||−.72||.48|
|Side-bendingNon-throwing||.26 ± 4.3°||.47 ± 4.0°||−.20°||−.14||.89|
Bilateral Comparison of ARE Within Pitchers and Position Players
|Group and Movement||Toward Throwing Arm's Side||Toward Non-throwing Arm's Side||Difference||t28Value||P|
|Pitchers (n = 17)|
| TLR||.53 ± 5.7°||.26 ± 6.1°||.26°||.13||.90|
| Side-bending||−.59 ± 3.5°||.26 ± 4.3°||−.85°||−.64||.53|
|Position players (n = 15)|
| TLR||−2.0 ± 5.4°||−.87 ± 4.4°||−1.2°||−.65||.52|
| Side-bending||.37 ± 4.0°||.47 ± 4.0°||−.10°||−.07||.95|