Experimental Approach to the Problem
Based on a previous study3, we recruit 20 participants for the present study. Participants familiar with baseball, over the age of 20, and could throw 100 pitches per game were included. Participants with dominant shoulder pain before pitching, sonographically diagnosed rotator cuff tendinopathy, or could not throw 100 pitches were excluded.
Subjects
Participants were recruited from an amateur college male baseball team at Taipei Medical University between October 2020 to February 2022. All participants signed informed consent forms and the protocol was approved by the Taipei Medical University Joint Institutional Review Board and all research was performed in accordance with relevant guidelines and regulations. The study was registered on Clinicaltrails.gov (NCT04504929, 07/08/2020).
Procedures
A physician evaluated participants for inclusion, arranged testing dates, and was responsible for tape application. The dominant shoulder of each participant was evaluated by sonography (minisono L3-12 linear transducer, Alpinion medical systems, Korea) by the same physician with Registered in Musculoskeletal® (RMSK®) sonography certification to exclude rotator cuff tendinopathy before starting the first test session.12 All participants underwent 2 separate tests consisting of 5 innings and 20 pitch counts in each inning. The interval between the 2 tests is longer than 1 week to insure post-exercise soreness and pain completely subsided. There is a 10-minute warm-up before each game. The pitch type is limited to 4-seam fast ball only, and participants were informed to pitch at maximal effort every pitch. The participants rested for 15 minutes between innings and less than 10 seconds between pitches. Before the second test, any post-exercise shoulder pain after first test must have completely subsided.
Participants received sham taping (elastic adhesive tape, 3M, USA) in 1 game and Dynamic taping in the other in a crossover design, the order of which was determined by an assessor using computer randomization. Internal rotation support taping method was applied in both sham and Dynamic taping. The dominant upper limb was first positioned in 90 degrees shoulder abduction in sagittal plane with elbow in 90 degrees flexion. The subjects were then asked to perform maximal internal rotation without scapula elevation. The physician applied tape to lateral part of arm proximal to elbow. The tape was then applied superiorly at a 45 degree angle to create a spiral effect from a posterior direction over the posterior glenohumeral joint and continued across the chest.10 (Fig. 1) The tape length is recorded in maximal internal rotation and maximal external rotation. After testing, a new piece of tape was cut according to the measured length at maximal internal rotation. The tape was then stretched to maximal external rotation length, and the generated force was measured by a digital algometer (Force Ten FDX Force Gage, Wagner Instruments, USA) to determine the internal force generated by the tape.13,14
During the tests, velocity and spin rate were recorded every pitch. Velocity was measured by Bushnell velocity speed gun which could track the speed of ball from 10 feet away up to 110 miles per hour(MPH) with ± 1.0MPH accuracy. Spin rate was measure by a scientific baseball training system (STRIKE smart baseball, Jingletek, Taiwan) which could measure the spin rate of a baseball from 100 rate per minute(RPM) to 4000 RPM with ± 85RPM accuracy. After pitching, participants recorded the severity of their shoulder soreness daily for one week using the visual analog scale to monitor delayed onset muscle soreness.15 At the end of the whole testing process, participants were asked to guess which taping session was done using the Dynamic tape.
Bilateral shoulder range of motion(ROM) and strength were measured just before game and immediately after game in sitting position with spine in neutral position. Tapes were not in place during the process. ROM was measured by protractor and strength measured by handheld dynamometer (JAMAR Plus, Patterson Medical, Canada) with a sensitivity of 0.01kg and calibrated according to the manufacturer’s recommendation. The handheld dynamometer is valid16 and has good test-retest reliability by our examiner (Pearson correlation coefficient = 0.96 in external rotation and 0.95 in internal rotation). Shoulder fatigue is defined as a strength decline. For ROM tests, participants were asked to perform maximal active movement in shoulder flexion, extension, abduction, internal rotation, and external rotation. Shoulder flexion, extension and abduction ROM were measured with elbow in full extension. Internal rotation and external rotation ROM were measured with shoulder in 90 degrees abduction in coronal/frontal plane and elbow in 90 degrees flexion. The shoulder flexion strength was first measured, followed by extension, abduction, internal rotation, and external rotation. Abduction strength was measured with shoulder in 30 degrees abduction. Internal rotation and external rotation were tested in 90 degrees elbow flexion and 90 degrees shoulder abduction.
An assessor blinded to group assignment was responsible for shoulder ROM, shoulder strength, pitching speed, spin rate, and tape generated force measurements.
Statistical Analyses
Pre-exercise shoulder ROM and strengths in dominant and non-dominant shoulder were compared by paired t tests in both Dynamic and sham tape groups. The post-exercise decrease of strength and percentage of strength decrease was calculated in both groups and bilateral shoulders. In both Dynamic and sham tape groups, the percent of shoulder strength decrease in the dominant versus nondominant shoulder was compared using paired t tests. Pitching speed and spin rate were averaged in every inning. Significant differences of pitching speed and spin rate between Dynamic tape and sham test were tested by paired t tests in every inning. Pitching speed and spin rates in the second, third, fourth and fifth innings were compared to first inning in both groups by one-sample t tests. The between group post exercise pain was compared by paired t test. A p-value of < .05 was deemed significant. At the end of test, the percentage of correct dynamic tape session recognition by participants was calculated. The magnitude of the differences between dynamic tape and sham tape was determined for outcome variables using the Cohen’s d (ie, effect size[ES]).17 ES of < 0.2, 0.2 ~ 0.5, 0.5 ~ 0.8, and > 0.8, differences were respectively considered trivial, small, moderate, and large.18