Experimental approach to the problem
Based on a previous study by Mullaney and considering a type 1 error of 0.05, power of 80%, 2-sided test, at least 18 participants were required [7]. We enrolled 20 participants for the current investigation. Eligible participants were individuals who were experienced in baseball, aged more than 20 years, and capable of throwing 100 pitches per game. The exclusion criteria included participants with preexisting dominant shoulder pain before pitching, those diagnosed with rotator cuff tendinopathies via sonography, or those unable to throw 100 pitches.
Subjects
Participants were recruited from an amateur college male baseball team at Taipei Medical University between October 2020 and February 2022. All participants provided signed informed consent forms, and the protocol received approval from the Taipei Medical University Joint Institutional Review Board. All research procedures were conducted in accordance with relevant guidelines and regulations. The study was registered on Clinicaltrials.gov (NCT04504929, 07/08/2020). This study was supported by a grant from Taipei Medical University – Wan Fang Hospital (Grant No. 109TMU-WFH-20), and there were no competing interests.
Procedures
A physician evaluated participants for inclusion, arranged testing dates, and was responsible for tape application. The dominant shoulder of each participant was assessed using sonography (minisono L3-12 linear transducer, Alpinion Medical Systems, Korea) by the same physician, who held Registered in Musculoskeletal® (RMSK®) sonography certification, to exclude rotator cuff tendinopathy before the commencement of the first test session [21]. All participants underwent two separate tests, each consisting of 5 innings and 20 pitch counts per inning. The interval between the two tests exceeded one week to ensure complete resolution of postpitching soreness and pain. A 10-min warm-up preceded each game. Due to varying biomechanics and unfamiliarity with off-speed pitches, we instructed all participants to throw only 4-seam fastballs at maximal effort for each pitch [9]. Participants rested for 15 min between innings and less than 10 s for setting, mirroring typical game conditions. This ensured realistic assessment of Dynamic Tape’s effects on shoulder fatigue and pitching performance. Before the second test, any postpitching shoulder pain following the first test must have completely subsided.
Participants received either sham taping (elastic adhesive tape, 3 M, USA) in one game and Dynamic taping (Dynamic Tape Global®) in the other, following a crossover design, with the order determined by an investigator using computer randomization. The internal rotation support taping method was applied in both the sham and Dynamic taping groups. The dominant upper limb was initially positioned at 90 degrees shoulder abduction in the sagittal plane with the elbow flexed at 90 degrees. Participants were then instructed to perform maximal internal rotation without scapula elevation. The physician applied tape to the lateral part of the arm proximal to the elbow. Subsequently, the tape was applied superiorly at a 45-degree angle to create a spiral effect from a posterior direction over the posterior glenohumeral joint, continuing across the chest [17] (Fig. 1). The tape length was recorded at maximal internal rotation and maximal external rotation. Following the testing, we recorded the taping force. A new piece of tape was cut according to the measured length at maximal internal rotation. The tape was then stretched to the maximal external rotation length, and the generated force was measured using a digital algometer (Force Ten FDX Force Gage, Wagner Instruments, USA) to determine the internal force exerted by the tape [22, 23].
Tape-to-internal rotation support
During the tests, the velocity and spin rate were recorded for every pitch. The velocity was measured using a Bushnell velocity speed gun capable of tracking ball speeds from 10 feet to 110 miles per hour (MPH) with ±1.0 MPH accuracy. The spin rate was measured using a scientific baseball training system (STRIKE Smart Baseball, Jingletek, Taiwan), which measures the spin rate of a baseball from 100 revolutions per minute (RPM) to 4000 RPM with ±85 RPM 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 [24]. At the end of the entire testing process, the participants were asked to guess which taping session utilized Dynamic tape.
Bilateral shoulder range of motion (ROM) and strength were assessed both before and immediately after the game, with participants seated and their spines in a neutral position. Tape was not applied during these assessments. ROM was measured using a clinical goniometer, while strength was evaluated using a handheld dynamometer (JAMAR Plus, Patterson Medical, Canada) with a sensitivity of 0.01 kg and calibrated according to the manufacturer’s recommendations. A handheld dynamometer, validated [25] and demonstrating good test-retest reliability by our examiner (Pearson correlation coefficient=0.96 for external rotation and 0.95 for internal rotation), was used. Shoulder fatigue was defined as a decrease in strength of maximal voluntary force [6, 7].
During the ROM tests, the participants were instructed to perform maximal active movements in shoulder flexion, extension, abduction, internal rotation, and external rotation. Shoulder flexion, extension, and abduction ROM were measured with the elbow in full extension, while internal rotation and external rotation ROM were measured with the shoulder abducted to 90 degrees in the coronal/frontal plane and the elbow flexed to 90 degrees.
The order of strength measurements was as follows: shoulder flexion, extension, abduction, internal rotation, and external rotation. Shoulder flexion and extension strength were both assessed with the shoulder at 0 degrees of flexion and the elbow in full extension. Abduction strength was assessed with the shoulder abducted to 30 degrees. The internal rotation and external rotation strength were tested with the elbow flexed to 90 degrees and the shoulder abducted to 90 degrees. After pitching, participants were asked for recording their dominant shoulder pain by numerical rating scale every day for one week.
An investigator, blinded to group assignment, was tasked with measuring shoulder ROM, shoulder strength, pitching speed, spin rate, and tape-generated force.
Statistical analyses
Pre-pitching and post-pitching shoulder ROM, strength, and strength decreases in both the dominant and non-dominant shoulders were compared between the dynamic and sham tape groups using independent t-tests. Within each shoulder (dominant or non-dominant), comparisons of pre-pitching and post-pitching ROM and shoulder strength were conducted using paired t-tests.
Pitching speed and spin rate were averaged for each inning. The differences in pitching speed and spin rates between the sham and dynamic taping groups were analyzed using two-way ANOVA. A significance level of p < 0.05 was used.
Post-pitching pain from days 2 through 7 was compared to pain on day 1 using paired t-tests.
At the conclusion of the test, tape force was compared between the dynamic and sham tape groups using independent t-tests. Participants’ ability to correctly identify the tape used was assessed, and the percentage of correct identifications was calculated. The magnitude of the differences between Dynamic tape and sham tape for outcome variables was determined using Cohen’s d (effect size [ES]) [26]. When the ES was <0.2, 0.2~0.5, 0.5~0.8, or >0.8, the differences were considered trivial, small, moderate, or large, respectively [27].
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