Effects of different frequencies of percussion massage therapy on pain, range of motion, functionality, joint position sense, and quality of life in individuals with rotator cuff tears: a randomized controlled trial

Abstract

Background

Rotator cuff tears often cause persistent pain, limited mobility, impaired proprioception, and functional decline. While conventional physiotherapy (CT) is the standard treatment, percussion massage therapy (PMT) has emerged as a vibration-based modality that may enhance neuromuscular activation and sensorimotor function. However, optimal PMT frequency parameters remain unclear. This randomized controlled trial examined the effects of two PMT frequencies (16.7 Hz and 33 Hz), combined with CT, on pain, range of motion (ROM), joint position sense (JPS), functionality, and quality of life in individuals with partial rotator cuff tears.

Methods

Forty-eight adults with supraspinatus partial tears were screened, and 45 were randomized into three groups: CT (n = 15), PMT at 16.7 Hz + CT (n = 15), and PMT at 33 Hz + CT (n = 15). Interventions were applied for three weeks. Primary outcomes included JPS (60° flexion and abduction). Secondary outcomes included Visual Analog Scale (VAS) for resting and activity-related pain, active ROM in all planes, Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and Rotator Cuff Quality of Life (RC-QoL). Assessments were conducted pre- and post-intervention.

Results

All groups showed significant improvements (p < 0.05), but both PMT groups demonstrated substantially greater gains than CT alone. The 33 Hz group showed the largest improvements, including + 71.7° flexion, + 77.0° abduction, and marked reductions in VAS-activity (r = − 0.89) and DASH (d = − 2.59). The 16.7 Hz group also improved significantly (flexion + 65.0°, abduction + 72.0°; DASH d = − 2.10). No between-group differences were observed in JPS, although all groups improved meaningfully.

Conclusions

PMT at both 16.7 Hz and 33 Hz, when added to CT, significantly improved pain, ROM, functional disability, and quality of life in individuals with rotator cuff tears, outperforming CT alone. Frequency-specific differences were not evident for proprioception, suggesting that additional sensorimotor training may be needed to optimize JPS recovery. PMT appears to be a safe and effective adjunct in shoulder rehabilitation.

Trial registration

Prospectively registered in the ClinicalTrials.gov registry (NCT06899945) on 21/03/2025.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13102-026-01581-4.

Background

Rotator cuff injuries are progressive pathologies that typically begin with acute tendinitis and may advance to partial or full-thickness tears due to ongoing degeneration [1]. Among the most common symptoms of partial rotator cuff tears are pain, reduced shoulder range of motion, impaired proprioception, and difficulty performing functional upper extremity activities [2]. Rotator cuff tears represent one of the most prevalent musculoskeletal disorders in industrialized countries, contributing to substantial direct and indirect healthcare costs. The prevalence ranges from 5 to 10% in individuals under the age of 20 to as high as 60% in those over the age of 80 [3]. Repetitive overhead activities, participation in strenuous sports, and trauma to the shoulder region are considered primary contributing factors. Management strategies for rotator cuff injuries include physiotherapy, pharmacological interventions, and surgical procedures [4]. However, conservative treatment approaches are frequently preferred, particularly in cases of partial tears. These approaches typically encompass range of motion exercises, strengthening and stretching routines, electrotherapy modalities, and manual therapy techniques [2, 5].

In recent years, vibration therapy has emerged as an increasingly utilized modality in the field of rehabilitation. This therapeutic approach is based on the principle of delivering mechanical oscillations directly to muscles or tendons via whole-body vibration platforms or local vibration devices [6]. Vibration therapy is thought to enhance central nervous system activation by stimulating joint mechanoreceptors, muscle spindles, cutaneous receptors, and vestibular structures, thereby inducing multilevel physiological changes within the musculoskeletal system [7]. Despite its growing use in both sports and rehabilitation settings, scientific evidence supporting the effectiveness of vibration-based interventions remains limited, particularly in clinical populations. In this context, the literature exhibits considerable heterogeneity regarding optimal application parameters, especially stimulation frequency. Lower-frequency percussive applications are predominantly used for pain modulation, presumably through the regulation of nociceptive input. In contrast, moderate-frequency applications are more commonly preferred for interventions targeting improvements in myofascial mobility and range of motion (ROM). Nevertheless, despite the widespread clinical adoption of these frequency-dependent approaches, studies directly comparing their differential effects on clinical outcomes particularly in symptomatic musculoskeletal populations remain scarce. This gap highlights the need for well-controlled clinical trials that systematically investigate the frequency-specific effects of percussion massage therapy (PMT) [8].

PMT is a novel intervention that integrates elements of traditional massage and vibration therapy. In recent years, handheld devices used for PMT have gained popularity due to their potential performance-enhancing benefits [9]. PMT has become one of the frequently used myofascial interventions aimed at reducing pain in both superficial and deep tissues, enhancing blood circulation, improving scar tissue healing, lowering lactate levels and muscle spasms, increasing lymphatic flow, inhibiting the golgi tendon reflex, and restoring normal joint range of motion [10]. There are various models of percussion massage devices with adjustable settings, including different speeds/frequencies (e.g., 17–53 Hz), amplitudes, and applicator heads (e.g., large and small balls, flat heads, pointed tips, fork attachments) [9].

Most existing studies in the literature have investigated the acute effects of PMT, reporting short-term improvements in joint range of motion, muscle strength, and pain. However, research exploring its effects on sensory and neuromuscular functions, such as proprioception, remains quite limited [11–13]. In a study conducted on healthy individuals, a five-minute PMT application to the posterior rotator cuff muscles led to increases in passive joint range of motion and muscle strength, along with a decrease in teres minor muscle thickness. These findings suggest that PMT may serve as a potential adjunctive treatment to enhance rotator cuff function [14].

Although PMT has gained considerable popularity among healthcare professionals in recent years, there is still no consensus regarding its optimal application protocols or effective frequency ranges. The scarcity of high-quality evidence and the lack of standardized, evidence-based guidelines create a notable gap between clinical practice and research. Consequently, many practitioners rely on personal experience or peer recommendations when determining treatment parameters. This variability in key factors such as duration, speed, and frequency makes it challenging to compare clinical outcomes and to achieve standardization in PMT applications [9]. Most studies on PMT have focused on its acute effects in healthy individuals, primarily targeting the lower extremities. Research investigating its effects on upper extremity pathologies is limited. Studies on lower extremity muscles have shown that PMT can acutely improve range of motion in muscles such as the gastrocnemius and hamstrings. Nevertheless, the findings in the literature remain inconsistent, and further research is needed to clarify its effectiveness, particularly in the upper extremities [15, 16].

Therefore, the aim of this study was to investigate the effects of PMT at different frequencies (33 Hz and 16.7 Hz), applied in addition to conventional physiotherapy, on pain, range of motion, functionality, joint position sense, and quality of life in individuals with rotator cuff tears. It was hypothesized that PMT at both frequencies, when used as an adjunct to conventional physiotherapy, would be more effective than conventional physiotherapy alone in improving pain, ROM, functionality, joint position sense (JPS), and quality of life in individuals with rotator cuff tears; however, no significant difference was expected between the two frequencies.

Methods

Study design and participants

This study was designed as a parallel-group, double-blind randomized controlled trial (blinding applied to participants and outcome assessors) with an equal allocation ratio of 1:1:1. The research was conducted at Istanbul Medipol University Hospital and received approval from the Non-Interventional Research Ethics Committee of Istanbul Medipol University (Approval No: E-10840098-202.3.3.3.02–1958). Written and verbal informed consent was obtained from all participants prior to enrollment. The study was carried out in accordance with the ethical principles outlined in the Declaration of Helsinki. Additionally, the trial was prospectively registered at ClinicalTrials.gov (Identifier: NCT06899945) to ensure methodological transparency. This randomized controlled trial was conducted and reported in accordance with the CONSORT (Consolidated Standards of Reporting Trials) guidelines. A completed CONSORT checklist is provided as an additional file.

Eligible participants were adults aged 30–60 years who had been diagnosed with chronic shoulder pain resulting from a partial tear of the supraspinatus muscle (rotator cuff), as confirmed by a physical medicine and rehabilitation physician through radiological imaging. All participants were recreationally active individuals and none were professional or competitive athletes, nor did they regularly participate in structured resistance training or overhead sports activities during the preceding six months. Participants with a history of shoulder surgery or concomitant orthopedic or cardiac comorbidities were excluded. Other exclusion criteria included the presence of systemic musculoskeletal or neurological disorders, engagement in a physiotherapy program within the past three months, and inability or unwillingness to comply with the study protocol.

During the recruitment period, 66 individuals diagnosed with partial rotator cuff tears were screened for eligibility. Of these, nine were excluded for not meeting the inclusion criteria. Among the remaining candidates, four declined participation in favor of alternative treatments, two withdrew due to personal reasons, one discontinued because of transportation issues, and two were excluded due to language barriers. As a result, 48 participants met the eligibility criteria and were randomly assigned to one of three intervention groups: Conventional Therapy (CT), PMT at 33 Hz, or PMT at 16.7 Hz, with 16 participants in each group. One participant from each group discontinued the intervention during the follow-up phase, yielding a final sample of 45 participants (n = 15 per group) for statistical analysis (Fig. 1).

Fig. 1.

Flow diagram of the study design

Randomization and blinding

Randomization was performed using a computer-generated sequence created via randomizer.org by an independent researcher who was not involved in participant enrollment, intervention delivery, or outcome assessments. Participants were equally allocated (1:1:1) to the three intervention arms CT, PMT (16.7 Hz), and PMT (33 Hz) through simple randomization without stratification. Allocation concealment was maintained using sequentially numbered, opaque, sealed envelopes prepared by the independent investigator.

In the interventions, participants were not informed about which specific treatment protocol they received; they were only told that they would participate in one of several validated physiotherapy protocols. This approach was used to minimize the risk of performance bias.

All interventions (CT and both PMT frequencies) were administered by the same licensed physiotherapist, who had over four years of clinical experience in musculoskeletal rehabilitation and specialized certification in vibration therapy. This ensured consistency and standardization across all treatment sessions. Outcome measures were assessed by an independent physiotherapist with ten years of experience in clinical and research settings, who remained blinded to group allocation. All statistical procedures and outcome interpretations were carried out by a biostatistician blinded to group allocation to ensure methodological rigor.

Conventional physiotherapy group

Participants in the CT group received a structured three-week rehabilitation protocol, administered five days per week under the supervision of a licensed physiotherapist. Each session lasted approximately 30 min. Exercise intensity was individually tailored and adjusted according to participants’ pain levels, functional capacity, and tolerance.

Sessions began with transcutaneous electrical nerve stimulation (TENS) applied to the painful area for 20 min at a frequency of 100 Hz. This was followed by a series of therapeutic exercises: wand exercises for shoulder flexion, abduction, extension, internal rotation, and external rotation (10 repetitions per set); Codman’s pendulum exercises performed passively in flexion, abduction, and circular motions (10 repetitions per set); both active and passive stretching exercises targeting flexion, abduction, and internal/external rotation (10 repetitions per set, with each stretch held for approximately 20 s); and finger ladder exercises for functional mobility enhancement in flexion and abduction. Strengthening exercises with elastic resistance bands were included for flexion, abduction, internal rotation, external rotation, and extension, with resistance levels progressively increased by modifying theraband tension and range of motion. All strengthening exercises were performed for 10 repetitions per set.

This CT protocol was uniformly applied across all groups to ensure a standardized comparator for evaluating additional interventions.

Percussion massage therapy (33 Hz) group

In addition to the CT protocol described above, participants in the PMT (33 Hz) group also received the full CT protocol along with moderate-intensity percussion massage therapy. The same Hypervolt device and standardized procedures were used. The device operated at level 2 (frequency: 33 Hz) and the flat head attachment was again used for uniform application. Massage was applied longitudinally to the same muscle groups (deltoid, supraspinatus, infraspinatus, and teres minor) with each session involving three minutes of treatment per muscle group and five-second strokes in both directions [17, 18]. The interventions were administered three times per week over a three-week period to minimize the risk of excessive tissue loading due to the mechanical nature of the intervention.

Percussion massage therapy (16.7 Hz) group

Similarly, participants in the PMT (16.7 Hz) group received low-intensity PMT using a Hypervolt device (Hyperice, CA, USA). The intervention was delivered by the same physiotherapist to ensure methodological consistency across sessions. The massage was applied along the anatomical course from the origin to the insertion of the deltoid, supraspinatus, infraspinatus, and teres minor muscles. The device was set to level 1 (frequency: 16.7 Hz) and equipped with a flat head attachment to ensure safe and consistent stimulation. Each muscle group was treated for three minutes with strokes applied longitudinally in both proximal-to-distal and distal-to-proximal directions, each lasting approximately five seconds [17, 18]. The intervention was administered three times per week for three consecutive weeks (Fig. 2).

Fig. 2.

Vibration therapy applied with percussion massage device

Outcome measures

Outcome assessments for all participants were conducted both prior to the initiation of the intervention and following the completion of the three-week treatment period.

Joint position sense

JPS was evaluated using the Becure Extremity ROM system. The Becure system is based on a motion-capture technology that utilizes the Microsoft Kinect sensor. The assessment focused on two specific shoulder movements: 60° of flexion and 60° of abduction. Participants were first asked to actively raise their arm to the target angle (60°) with their eyes open in order to perceive and memorize the position. They were then instructed to return to the starting position and reproduce the same movement with their eyes closed, relying solely on proprioceptive memory. The shoulder angle reached during the eyes-closed trial was recorded using the Becure application.

The absolute angular error, defined as the difference between the reference angle (eyes open) and the reproduced angle (eyes closed), was used to quantitatively assess the accuracy of JPS. For each movement direction, participants reached the target angle first with visual feedback and then without it. The angular deviation between these two positions was calculated as the joint position error. Lower error values indicated greater proprioceptive acuity [19, 20].

Secondary outcomes

Pain

Pain intensity was assessed using the Visual Analog Scale (VAS), a 10-centimeter horizontal line anchored by two descriptors: “0” representing no pain and “10” indicating the worst imaginable pain. Participants were instructed to mark the point on the line that best reflected their current pain intensity. The pain score was then determined by measuring the distance in centimeters from the left endpoint to the participant’s mark using a standard ruler [21].

Assessment of range of motion

Range of motion (ROM) was assessed using the Becure Extremity ROM system. This system enables objective measurement of joint mobility by detecting reference points during extremity movements through its integrated camera and sensors. In the Becure Extremity ROM setup, participants are instructed to stand in front of the camera and perform the specific movement to be measured. In the present study, shoulder joint ROM (including flexion, abduction, internal rotation, and external rotation) was evaluated in degrees using the Becure Extremity ROM system [22, 23].

Functionality

To evaluate shoulder function and disability, the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire developed by Hudak et al. was utilized. This instrument evaluates both the physical capabilities and symptom severity of individuals with upper limb musculoskeletal conditions [24]. It consists of 30 items in total, including 6 items related to symptoms and 24 items addressing functional performance. Participants respond to each item using a 5-point Likert scale. The total score ranges from 0 to 100, with higher scores reflecting a greater level of disability [25].

Quality of life

Quality of life was assessed using the Rotator Cuff Quality of Life (RC-QoL) questionnaire. The RC-QoL consists of 34 items distributed across five subdomains: physical symptoms, work-related activities, activities of daily living, social well-being, and emotional well-being. Each item is scored on a scale from 0 to 100, and the total score is expressed as a percentage. Higher scores indicate better quality of life [26].

Statistical analysis

An a priori power analysis was conducted using G*Power software (version 3.1.9.7) to determine the required sample size for detecting statistically significant differences in the primary outcome, shoulder JPS, measured as absolute angular error. A one-way analysis of variance (ANOVA) was planned to compare three independent groups. The expected effect size (ES) was set at f = 0.40, which corresponds to a moderate-to-large magnitude, based on previously published values of Cohen’s d ranging from 0.51 to 0.84 as reported by Alfaya et al. [27]. With a significance level (α) of 0.05 and a power (1–β) of 0.80, the minimum required sample size was calculated as 45 participants (15 per group). To account for potential attrition, 48 participants were initially enrolled.

All statistical analyses were conducted using IBM SPSS Statistics (version 22.0; IBM Corp., Armonk, NY, USA), with the overall level of statistical significance set at p < 0.05. Data distribution and suitability for parametric analyses were examined prior to statistical testing, and appropriate tests were applied accordingly. The normality of continuous variables was tested using the Shapiro–Wilk test. Based on distributional characteristics, either parametric or non-parametric methods were employed.

Descriptive statistics were presented as means and standard deviations (mean ± SD) for continuous variables and frequencies and percentages (n, %) for categorical variables. For baseline comparisons between the three groups one-way ANOVA was used for normally distributed variables, the Kruskal–Wallis test was used for non-normally distributed variables, and the chi-square test was used for categorical variables such as gender, dominant side, and injured shoulder. Within-group comparisons between pre- and post-treatment data were performed using paired samples t-tests for normally distributed variables and Wilcoxon signed-rank tests for non-normally distributed variables. Between-group comparisons of post-intervention outcomes were conducted using one-way ANOVA or Kruskal–Wallis tests, based on data distribution. When significant differences were observed among the three groups, pairwise comparisons were conducted using Tukey’s Honestly Significant Difference (HSD) test. To reduce the risk of Type I error due to multiple testing, Bonferroni correction was applied, adjusting the significance threshold to p < 0.017.

ESs were calculated to determine the magnitude of change within and between groups. For parametric data, Cohen’s d values were calculated using pooled SDs and were interpreted as small (0.20–0.49), medium (0.50–0.79), and large (≥ 0.80). For non-parametric data, the rank-biserial correlation coefficient (r = Z/√N) was used and interpreted as small (0.10–0.29), medium (0.30–0.49), and large (≥ 0.50) [28, 29].

In addition to statistical significance, minimal clinically important difference (MCID) values were considered to evaluate the clinical importance of changes. Based on prior research, the MCID thresholds for shoulder-related conditions were defined as follows: a reduction of ≥ 10.2 points for DASH [30], a decrease of 1.4–2.0 cm on the VAS for pain [31], and an increase of 10°–15° for shoulder ROM in flexion and abduction [32]. Although no universally accepted MCID exists for the RC-QoL questionnaire, a change of at least 13 points was suggested to represent meaningful improvement [33]. All MCID thresholds were used as interpretative references to determine whether statistically significant outcomes were also clinically meaningful.

Results

All participant groups were comparable in terms of demographic and clinical characteristics. No statistically significant differences were observed between the PMT (33 Hz), PMT (16.7 Hz), and CT groups in terms of age, sex distribution, dominant or affected side, symptom duration, pain level (VAS at rest and during activity), shoulder ROM (flexion, abduction, internal and external rotation), JPS in flexion and abduction, functional disability (DASH), or quality of life (RC-QoL) scores (p > 0.05). These findings indicate baseline homogeneity between the groups (Table 1). All three groups showed statistically significant improvements in all outcome measures between pre- and post-intervention (p < 0.05), although the magnitude of change differed between groups. In the PMT (33 Hz) group, significant increases were observed in ROM/flexion (+ 71.7°) and ROM/abduction (+ 77.0°), with very large ESs (Cohen’s d = 6.22 and 7.96, respectively). Internal and external rotation also improved (d = 3.02 and 0.88). Significant reductions were observed in VAS-resting (d = − 1.95), VAS-activity (r = − 0.86), and DASH scores (d = − 2.59), alongside an increase in RC-QoL (d = 2.63). In the PMT (16.7 Hz) group, all parameters also showed significant improvements. ROM/flexion and abduction increased by + 65.0° and + 72.0°, respectively, with very large ESs (d = 6.57 and 6.89). Other ROM variables, DASH, and RC-QoL scores also improved significantly (DASH: d = − 2.10; RC-QoL: d = 2.06). In the CT group, more limited improvements were observed. ROM/flexion increased by approximately 26°, with a moderate ES (d = 1.64). Other measures such as DASH (d = − 0.80) and JPS showed statistically significant but smaller changes. These findings indicate that natural recovery contributed partially to functional gains (Table 2). Statistically significant differences were found between groups in VAS-resting, VAS-activity, all ROM directions (flexion, abduction, internal and external rotation), DASH, and RC-QoL scores (p < 0.001) (Table 3). No significant differences were observed between groups in JPS/flexion and JPS/abduction (p > 0.05). The PMT (33 Hz) group demonstrated the highest improvements in all parameters, with very large effect sizes compared to the CT group. ROM/flexion and abduction increased by 71.7° and 77.0°, respectively (d = 3.08 and 2.71), VAS-activity significantly decreased (r = − 0.89), and greater improvements were observed in VAS-resting (d = − 0.85). In the PMT (16.7 Hz) group, improvements were lower than in the PMT (33 Hz) group but remained clinically relevant. Large effect sizes were observed in ROM/flexion (d = 2.99), ROM/abduction (d = 2.46), and DASH (d = − 1.87). No statistically significant differences were found between the PMT (33 Hz) and PMT (16.7 Hz) groups (p > 0.05). However, some variables such as ROM/internal rotation (d = 0.66) and VAS-resting (d = − 0.61) showed moderate-to-large ESs. Although JPS scores did not differ significantly between groups, within-group improvements were observed in both intervention groups. DASH and RC-QoL scores were significantly better in both vibration groups compared to the CT group, with the greatest improvement in the PMT (33 Hz) group (DASH: d = − 2.02; RC-QoL: d = 1.31). To assess the clinical significance of these findings, minimal clinically important difference (MCID) thresholds were considered. For the DASH, changes exceeding 10.2 points are considered clinically meaningful, and the reduction observed particularly in the PMT (33 Hz) group (–43.33 points) far surpassed this threshold [34]. For the VAS, reductions of 1.4–2.0 cm are regarded as clinically important; the decreases observed in the present study were substantially greater than these values [31, 35]. Improvements in ROM clearly exceeded the MDC values reported for shoulder flexion and abduction, which typically range from 10° to 15° [36]. For the RC-QoL, increases greater than 13 points have been suggested as clinically meaningful [37] and this threshold was exceeded across all three groups. ESs are reported alongside p-values to facilitate interpretation of the magnitude and clinical relevance of the observed changes.

Table 1.

Baseline demographic and clinical characteristics of participants across intervention groups

Variables	PMT (33 Hz) (n = 15) (mean ± SD)	PMT (16,7 Hz) (n = 15) (mean ± SD)	CT (n = 15) (mean ± SD)	p
Age (years)	44.73 ± 7.96	48.00 ± 7.43	46.67 ± 6.22	0.468a
Gender, F/M (F%)	7/15 (46.7%)	5/15 (33.3%)	8/15 (53.3%)	0.533b
Dominant side, R/L (R%)	11/15 (73.3%)	13/15 (86.7%)	11/15 (73.3%)	0.598b
Injured side, R/L (R%)	8/15 (53.3%)	10/15 (66.7%)	8/15 (53.3%)	0.695b
Duration (months)	2.33 ± 1.28	2.37 ± 1.20	2.17 ± 1.22	0.893c
VAS-resting	3.73 ± 2.12	2.67 ± 1.35	3.67 ± 1.95	0.216a
VAS-activity	7.07 ± 1.91	6.13 ± 1.41	6.73 ± 1.49	0.259c
ROM/Flexion	106.33 ± 15.64	112.67 ± 13.21	110.47 ± 17.98	0.539a
ROM/Abduction	92.67 ± 10.67	96.33 ± 12.17	94.20 ± 18.46	0.778a
ROM/IR	45.67 ± 10.15	50.00 ± 11.02	45.87 ± 17.18	0.599a
ROM/ER	42.00 ± 6.21	45.00 ± 8.02	43.47 ± 13.79	0.382c
JPS/Flexion	9.00 ± 2.07	9.00 ± 2.07	9.67 ± 2.58	0.325c
JPS/Abduction	9.67 ± 3.99	10.33 ± 4.42	9.13 ± 2.29	0.868c
DASH	54.44 ± 20.82	52.16 ± 22.52	59.36 ± 12.15	0.575a
RC-QoL	46.47 ± 19.71	49.13 ± 21.65	47.50 ± 8.26	0.916a

PMT Percussion massage therapy, CT Conventional Therapy, SD Standart deviation, F Female, M Male, R Right, L Left, VAS Visual analog scale, ROM Range of motion, IR Internal rotation, ER External rotation, JPS Joint position sense, DASH Disabilities of the Arm, Shoulder, and Hand Questionnaire, RC-QoL Rotator Cuff Quality of Life

^aOne-way analysis of variance (ANOVA), ^bChi-square Test, ^cKruskal–Wallis Test, p < 0.05

Table 2.

Comparison of the values pre-treatment and post-treatment within the group

Variable	Pre- PMT (33 Hz) (Mean ± SD) 95% CI (Lower/Upper)	Post- PMT (33 Hz) (Mean ± SD) 95% CI (Lower/Upper)	pa, b	ES	Pre- PMT (16.7 Hz) (Mean ± SD) 95% CI (Lower/Upper)	Post- PMT (16.7 Hz) (Mean ± SD) 95% CI (Lower/Upper)	pa, b	ES	Pre-CT (Mean ± SD) 95% CI (Lower/Upper)	Post-CT (Mean ± SD) 95% CI (Lower/Upper)	pa, b	ES
VAS-resting	3.73 ± 2.12	0.67 ± 0.62	< 0.001a	−1.95	2.67 ± 1.35	0.60 ± 0.51	< 0.001a	−2.02	3.67 ± 1.95	1.93 ± 1.58	< 0.001a	−0.98
	(2.56/4.91)	(0.32/1.01)			(1.92/3.41)	(0.32/0.88)			(2.59/4.75)	(1.06/2.81)
VAS-activity	7.07 ± 1.91	2.07 ± 0.88	0.001b	−0.86	6.13 ± 1.41	2.07 ± 1.03	0.001b	−0.85	6.73 ± 1.49	4.80 ± 1.66	0.001b	−0.52
	(6.01/8.12)	(1.58/2.56)			(5.35/6.91)	(1.49/2.64)			(5.91/7.56)	(3.88/5.72)
ROM/Flexion	106.33 ± 15.64	178.00 ± 4.55	< 0.001a	6.22	112.67 ± 13.21	177.67 ± 4.58	< 0.001a	6.57	110.47 ± 17.98	136.47 ± 13.19	< 0.001a	1.64
	(97.67/114.99)	(175.48/180.52)			(105.35/119.98)	(175.13/180.20)			(100.51/120.42)	(129.16/143.77)
ROM/Abduction	92.67 ± 10.67	169.67 ± 8.55	< 0.001a	7.96	96.33 ± 12.17	168.33 ± 8.38	< 0.001a	6.89	94.20 ± 18.46	126.00 ± 28.25	< 0.001a	1.33
	(86.76/98.57)	(164.93/174.40)			(89.59/103.07)	(163.69/172.97)			(83.98/104.42)	(110.35/141.65)
ROM/IR	45.67 ± 10.15	78.33 ± 11.44	< 0.001a	3.02	50.00 ± 11.02	76.00 ± 11.53	< 0.001a	2.30	45.87 ± 17.18	56.40 ± 16.66	< 0.001a	0.62
	(40.04/51.29)	(72.00/84.67)			(43.90/56.10)	(69.62/82.38)			(36.35/55.38)	(47.17/65.63)
ROM/ER	42.00 ± 6.21	77.33 ± 11.93	0.001b	0.88	45.00 ± 8.02	75.67 ± 11.16	0.001b	0.84	43.47 ± 13.79	55.67 ± 14.41	0.001b	0.39
	(38.56/45.44)	(70.73/83.94)			(40.56/49.44)	(69.49/81.85)			(35.83/51.10)	(47.69/63.64)
JPS/Flexion	9.00 ± 2.07	6.00 ± 3.38	0.007b	−0.47	9.00 ± 2.07	6.00 ± 3.87	0.007b	−0.43	9.67 ± 2.58	7.67 ± 3.44	0.007b	−0.31
	(7.85/10.15)	(4.13/7.87)			(7.85/10.15)	(3.86/8.14)			(8.24/11.10)	(5.76/9.57)
JPS/Abduction	9.67 ± 3.99	6.33 ± 4.42	0.031b	−0.36	10.33 ± 4.42	7.33 ± 5.30	0.021b	−0.29	9.13 ± 2.29	7.53 ± 2.61	0.004b	−0.31
	(7.45/11.88)	(3.89/8.78)			(7.89/12.78)	(4.40/10.27)			(7.86/10.40)	(6.09/8.98)
DASH	54.44 ± 20.82	11.11 ± 11.06	< 0.001a	−2.59	52.16 ± 22.52	13.61 ± 12.72	< 0.001a	−2.10	59.36 ± 12.15	49.22 ± 12.99	< 0.001a	−0.80
	(42.91/65.97)	(4.98/17.24)			(39.69/64.63)	(6.56/20.65)			(52.63/66.09)	(42.03/56.41)
RC-QoL	46.47 ± 19.71	88.47 ± 10.99	< 0.001a	2.63	49.13 ± 21.65	85.07 ± 11.70	< 0.001a	2.06	47.50 ± 8.26	68.50 ± 10.55	< 0.001a	2.21
	(35.55/57.38)	(82.38/94.55)			(37.14/61.12)	(78.59/91.54)			(42.93/52.08)	(62.66/74.34)

PMT Percussion massage therapy, CT Conventional Therapy, SD Standart deviation, F Female, M Male, R Right, L Left, VAS Visual analog scale, ROM Range of motion, IR Internal rotation, ER External rotation, JPS Joint position sense, DASH Disabilities of the Arm, Shoulder, and Hand Questionnaire, RC-QoL Rotator Cuff Quality of Life, CI Confidence Interval, ES Effect Size

Paired sample t-test (a) was used for normally distributed variables, and Wilcoxon signed-rank test (b) for non-normally distributed variables. ESs were calculated using Cohen’s d (based on pooled standard deviation) for parametric variables and rank-biserial correlation (r = Z/√N) for non-parametric variables. Negative ES values in VAS, DASH, and JPS represent clinically favorable improvements due to score reductions. Bold values indicate statistically significant differences (p < 0.05)

Table 3.

Intra-group differences in values pre-treatment and post-treatment, and comparison of differences between groups

Variable	PMT (33 Hz) (Mean ± SD) 95% CI (Lower/Upper)	PMT (16.7 Hz) (Mean ± SD) 95% CI (Lower/Upper)	CT (Mean ± SD) 95% CI (Lower/Upper)	Diff p	p (CT- PMT 33 Hz)	ES	p (CT- PMT 16.7 Hz)	ES	p (PMT 33 Hz- PMT 16.7 Hz)	ES
VAS-resting	−3.07 ± 1.87 (−4.10/−2.03)	−2.07 ± 1.33 (−2.81/−1.33)	−1.73 ± 1.16 (−2.38/−1.09)	0.001a	0.026	−0.85	0.471	−0.26	0.102	−0.61
VAS-activity	−5.00 ± 1.69 (−5.94/−4.06)	−4.07 ± 1.22 (−4.74/−3.39)	−1.93 ± 1.03 (−2.51/−1.36)	< 0.001b	< 0.001	−0.89	< 0.001	−0.84	0.138	−0.31
ROM/Flexion	71.67 ± 16.00 (62.81/80.53)	65.00 ± 12.54 (58.06/71.94)	26.00 ± 13.46 (18.54/33.46)	< 0.001a	< 0.001	3.08	< 0.001	2.99	0.214	0.46
ROM/Abduction	77.00 ± 13.07 (69.76/84.24)	72.00 ± 12.22 (65.23/78.77)	31.80 ± 19.53 (20.98/42.62)	< 0.001a	< 0.001	2.71	< 0.001	2.46	0.288	0.39
ROM/IR	32.67 ± 9.80 (27.24/38.09)	26.00 ± 10.21 (20.34/31.66)	10.53 ± 6.55 (6.91/14.16)	< 0.001a	< 0.001	2.65	< 0.001	1.80	0.078	0.66
ROM/ER	35.33 ± 9.54 (30.05/40.61)	30.67 ± 10.67 (24.76/36.57)	12.20 ± 6.67 (8.51/15.89)	< 0.001b	< 0.001	0.95	< 0.001	0.90	0.224	0.25
JPS/Flexion	−3.00 ± 3.16 (−4.75/−1.25)	−3.00 ± 3.16 (−4.75/−1.25)	−2.00 ± 1.93 (−3.07/−0.93)	0.416b	---	---	---	---	---	---
JPS/Abduction	−3.33 ± 5.23 (−6.23/−0.44)	−3.00 ± 4.14 (−5.29/−0.71)	−1.60 ± 1.40 (−2.38/−0.82)	0.662b	---	---	---	---	---	---
DASH	−43.33 ± 22.51 (−55.80/−30.87)	−38.55 ± 20.76 (−50.05/−27.06)	−10.15 ± 5.32 (−13.09/−7.20)	< 0.001a	< 0.001	−2.02	< 0.001	−1.87	0.550	−0.22
RC-QoL	42.00 ± 21.57 (30.06/53.94)	35.93 ± 19.68 (25.03/46.83)	20.87 ± 6.96 (17.01/24.72)	< 0.001a	0.001	1.31	0.009	1.02	0.427	0.29

PMT Percussion massage therapy, CT Conventional Therapy, SD Standart deviation, F Female, M Male, R Right, L Left, VAS Visual analog scale, ROM Range of motion, IR Internal rotation, ER External rotation, JPS Joint position sense, DASH Disabilities of the Arm, Shoulder, and Hand Questionnaire, RC-QoL Rotator Cuff Quality of Life, CI Confidence Interval, ES Effect Size, diff difference

One-way ANOVA (a) was used for normally distributed variables, and the Kruskal–Wallis test (b) for non-normally distributed variables. ESs were calculated using Cohen’s d for parametric variables and rank-biserial correlation (r = Z/√N) for non-parametric variables. Negative ES values in VAS, DASH, and JPS indicate clinically meaningful improvements due to score reductions. Post-hoc comparisons were conducted only when overall group differences were statistically significant (p < 0.017). Bold values indicate statistically significant differences. In certain cases, ES values were reported regardless of statistical significance to reflect potential clinical relevance

Discussion

This randomized controlled trial investigated the effects of PMT applied at two different frequencies (16.7 Hz and 33 Hz), in addition to conventional physiotherapy, on pain, ROM, functionality, JPS, and quality of life in individuals with rotator cuff tears. The findings indicated that PMT at both frequencies was associated with statistically significant improvements in pain, ROM, functionality, and quality of life compared with conventional physiotherapy alone, demonstrating the additional therapeutic benefits of PMT; however, no significant differences were observed between the groups in terms of JPS. Moreover, no statistically significant differences were identified between the two PMT frequencies. These findings suggest that PMT may contribute to neuromuscular and sensorimotor improvement when used as an adjunct to conventional physiotherapy. Within the tested mid-frequency range (approximately 17–33 Hz), both frequencies demonstrated comparable clinical effectiveness, implying that the observed benefits are more likely attributable to the application of vibration therapy itself than to small frequency variations. Accordingly, while the findings partially support our hypothesis that adjunctive PMT may enhance rehabilitation outcomes compared with standard treatment alone, they do not provide evidence of frequency-specific clinical superiority. The absence of frequency-dependent differences challenges the notion that “higher vibration equals better results” and underscores the need to consider individual variability in treatment responses. While conventional physiotherapy alone achieved clinically meaningful improvements exceeding MCID thresholds, adjunctive PMT resulted in greater between-group differences at the post-intervention level, supporting its role as an additive intervention rather than a replacement for standard care. Any apparent differences between the 16.7 Hz and 33 Hz conditions observed in effect size estimates should therefore be interpreted as exploratory and descriptive, rather than as evidence of frequency-specific clinical efficacy, given the absence of statistically significant between-group differences.

Our findings are consistent with several studies investigating the effectiveness of vibration and PMT in musculoskeletal rehabilitation. Although the current evidence base for the use of vibration therapy and PMT in shoulder pathologies remains limited, several studies conducted in other musculoskeletal conditions support the analgesic and mobility-enhancing effects of such modalities. For instance, a six-week percussive massage therapy intervention significantly reduced thoracolumbar fascia echo-intensity, alleviated low back pain, and improved disability in firefighters with chronic non-specific low back pain [38]. Seju and Rajput demonstrated that 2 weeks of thrice-weekly PMT treatment for upper trapezius myalgia led to greater pain relief and cervical ROM gains than electrical stimulation or no treatment [39]. Furthermore, a systematic review by Ferreira et al. concluded that massage guns offer short-term benefits in terms of increased flexibility and reduced muscle soreness [40]. Collectively, these findings align with the functional gains observed in our study and provide indirect support for the therapeutic value of PMT in shoulder rehabilitation. That review noted multiple studies where localized vibration at ~ 30–50 Hz acutely increased joint ROM or muscle performance, which aligns with our findings of functional gains. Taken together, the literature corroborates that vibration-based interventions are effective adjuncts in musculoskeletal rehab, including for shoulder pathologies, by reducing pain, improving ROM, and even modestly enhancing proprioception and strength. Jung and Ha demonstrated that a single session of local vibration significantly increased shoulder internal rotation and horizontal adduction ROM in individuals with posterior shoulder tightness [41]. In another randomized controlled trial, a 5-minute application of PMT to the shoulder muscles was shown to enhance proprioceptive acuity and improve functional test scores, even surpassing the effects of dynamic stretching and kinesiotaping [20]. This study supports our findings and suggests that PMT positively influences both sensorimotor function and overall functionality. Although very large within-group effect sizes were observed for shoulder ROM outcomes, these estimates warrant cautious interpretation. They primarily reflect substantial absolute pre–post improvements combined with reduced post-intervention variability, rather than an overestimation of treatment effects. Accordingly, effect sizes were reported to describe within-group responsiveness, while between-group comparisons and MCID thresholds were prioritized for clinical interpretation. Although many studies in this field have reported positive outcomes, it is important to acknowledge that not all findings have been consistent. For example, one study conducted in postoperative rotator cuff patients indicated that daily application of low-amplitude vibration at a high frequency (80 Hz) did not produce significant improvements in pain reduction or recovery when compared to placebo. This suggests that excessively high frequencies or application during the early postoperative period may limit the therapeutic efficacy of vibration therapy [42]. In contrast, our study demonstrated meaningful improvements in individuals with chronic rotator cuff syndrome using moderate frequencies (16.7–33 Hz), implying that both optimal frequency and appropriate timing of application may be critical determinants of therapeutic effectiveness.

Some evidence suggests that lower frequencies may be more effective for specific outcomes. For instance, one study reported that recovery from fatigue improved more consistently at 36 Hz, whereas this effect diminished at 53 Hz. This may help explain why the 33 Hz frequency in our study did not offer additional benefits over 16.7 Hz. Both frequencies fall within the moderate range and may have exceeded the threshold necessary to elicit therapeutic effects, while higher frequencies may trigger different physiological responses. Overall, our findings support the beneficial effects of vibration therapy on pain and function, and offer a novel perspective suggesting that frequency variations within the 17–33 Hz range do not significantly alter clinical outcomes [40].

In our study, all groups demonstrated significant improvements in JPS following the intervention. However, no statistically significant differences were observed between the groups in terms of JPS changes. This suggests that all three interventions may be effective in enhancing proprioceptive sensitivity, but none showed a clear superiority over the others. Several possible explanations may account for these findings. First, both PMT applications (16.7 Hz and 33 Hz) and conventional exercise therapy may have provided sufficient afferent stimulation to induce short-term improvements in JPS. Both vibration frequencies fall within a moderate range capable of activating slowly adapting mechanoreceptors and muscle spindles, potentially exceeding the physiological threshold required for proprioceptive gains. Meanwhile, conventional exercises—by involving active movement and motor control may have also contributed to proprioceptive improvements. Second, more pronounced enhancement of proprioception may require longer-term and task-specific sensorimotor training. Since PMT is a passive intervention and the duration of our study was relatively short, it is likely that the improvement in JPS remained limited. Additionally, reductions in pain may have indirectly enhanced proprioceptive acuity, as pain is known to impair proprioception [43]. Indeed, significant pain reduction was observed in all groups, which may have contributed to the improvements in JPS. In conclusion, our findings indicate that both PMT and conventional exercises are effective in improving JPS, but neither the frequency of vibration nor the type of intervention conferred a distinct advantage in the short term. From a clinical perspective, these results suggest that incorporating PMT into rehabilitation protocols may be a safe and beneficial strategy for enhancing proprioception. However, for optimal outcomes, it may be necessary to integrate additional active proprioceptive training into the treatment regimen. Supporting this, Maenhout et al. have reported that shoulder proprioception may not fully normalize without targeted neuromuscular rehabilitation interventions [44].

Another possible explanation is related to the stimulation parameters used in the present study. In the literature, the proprioception-enhancing effects of PMT have typically been reported with longer application durations (> 5 min) and higher vibration frequencies ranging between 30 and 50 Hz. In our study, however, PMT was applied at relatively lower frequencies (16.7 and 33 Hz) and for shorter durations (3 min per muscle group). These parameters might have been below the optimal proprioceptive stimulation threshold required to induce sufficient activation of muscle spindles and joint mechanoreceptors. Consequently, the lack of frequency-dependent differences and the modest improvements observed in JPS could be partly attributed to subthreshold mechanical stimulation intensity. Future research should incorporate longer intervention periods and include extended follow-up assessments to evaluate the sustainability of gains achieved through PMT. Additionally, studies are needed to identify optimal stimulation parameters such as frequency, amplitude, duration, and applied pressure to maximize proprioceptive and functional outcomes. Comparing PMT with other neuromodulatory interventions, including vibration platforms, tactile stimulation, or neuromuscular electrical stimulation, may further clarify its relative clinical effectiveness. Moreover, investigating the potential synergistic effects of combining PMT with active proprioceptive training would provide valuable insights into enhancing sensorimotor recovery.

There are several limitations that should be considered when interpreting the findings of this study. First, the relatively short duration of the intervention (three weeks) may have limited the development of long-term neuromuscular and proprioceptive adaptations typically associated with sensorimotor training. Although clinically meaningful improvements were observed, the absence of a long-term follow-up prevents drawing conclusions about the durability of PMT-related gains. Second, the PMT parameters specifically the 3-minute application per muscle group and the moderate frequencies used (16.7 and 33 Hz) may have been below the optimal thresholds reported in previous studies aiming to enhance proprioception. Longer application durations or higher-intensity protocols might produce different outcomes, particularly with respect to JPS. Third, JPS was assessed only at a single target angle (60°) during shoulder flexion and abduction, which limits the evaluation of angle-specific proprioceptive performance and restricts the generalizability of the findings to other joint positions. Although PMT was applied less frequently than conventional therapy, it was implemented strictly as an adjunct to an identical CT protocol; therefore, any potential influence of treatment frequency asymmetry is more likely related to the additive effect of PMT rather than differences in overall rehabilitation dosage. Finally, although all participants had partial rotator cuff tears, tear size was not quantitatively assessed; therefore, the presence of small-sized partial tears cannot be excluded. Given that smaller partial tears are generally associated with better preservation of range of motion and more favorable responses to conservative treatment, this factor may have partially contributed to the magnitude of the observed ROM improvements.

Conclusion

In conclusion, this randomized controlled trial suggests that PMT applied at either 16.7–33 Hz, when used in addition to conventional physiotherapy, is associated with meaningful improvements in pain, shoulder ROM, functional status, and quality of life in individuals with rotator cuff injuries. Both PMT frequencies showed comparable short-term effects and were associated with greater improvements than conventional therapy alone under the conditions tested, suggesting that the therapeutic benefits arise from the application of vibration itself rather than specific frequency differences within this range. Although proprioception improved across all groups, no frequency-dependent differences were observed, indicating that PMT alone may be insufficient to elicit distinct proprioceptive advantages without additional targeted sensorimotor training. Overall, PMT appears to be a safe, accessible, and clinically valuable adjunctive modality in the rehabilitation of rotator cuff dysfunction. Nevertheless, larger-scale studies including diverse clinical populations, optimized treatment parameters, and long-term follow-up are required to confirm the generalizability and durability of these findings.

Authors’ contributions

ED: Supervision, Conceptualization, Methodology, Writing – original draft, BM: Conceptualization, Investigation, Methodology, Writing – review & editing, BNE: Conceptualization, Investigation, MYM: Writing – review & editing.

Funding

This research received no external funding.

Data availability

The data supporting this study’s findings are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

All participants signed written informed consent forms, and the study was conducted according to the principles of the Declaration of Helsinki. The study protocol received approval from the non-interventional ethics committee at Istanbul Medipol University (File number: E-10840098-202.3.02-1958). All participants provided written informed consent.

Consent for publication

Written consent for publication has been obtained from the patient shown in Fig. 2.

Competing interests

The authors declare no competing interests.