Ⅰ. Introduction
Hypertonicity of the upper trapezius muscle is a prevalent musculoskeletal issue in modern populations, largely attributable to occupational and lifestyle changes. Prolonged use of computers and smart devices increases upper trapezius activation, leading to chronic tension and pain that adversely affects daily function and quality of life (Ko & Jeun, 2020; Li et al., 2024; Taş et al., 2018; Umair et al., 2024). Additionally, previous research indicates that upper trapezius hypertonicity may influence the physical properties of the middle trapezius, altering its tension and stiffness, which further exacerbates postural imbalance and functional limitation (Gillani et al., 2020; Li et al., 2024).
Sustained upper trapezius hypertonicity is closely associated with chronic cervical imbalance, leading to neck dysfunction, restricted mobility, and impaired shoulder movement (Sasaki & Miyamoto, 2024; Taş et al., 2018). Prolonged muscular stiffness in the upper trapezius further increases the risk of musculoskeletal injuries through excessive mechanical loading (Cai et al., 2023). Moreover, studies have reported altered muscle activation patterns in individuals with subacromial pain, including reduced serratus anterior activity and compensatory overactivation of the upper trapezius (Camargo & Neumann, 2019; Huang et al., 2022; Kawabuchi et al., 2024). These findings underscore the biomechanical significance of the upper trapezius in maintaining movement efficiency and postural stability.
Given these biomechanical implications, researchers have explored various intervention strategies. Among these, stretching exercises are a commonly used and effective method for relieving upper trapezius hypertonicity. Stretching has been widely recognized for its role in improving cervical mobility and reducing muscle stiffness (Park et al., 2013). It induces changes in muscle viscoelasticity, neuromuscular activation, and connective tissue remodeling, which can lead to long-term improvements in flexibility and functional mobility (Arntz et al., 2023; Freitas et al., 2018; Fukaya et al., 2022). Recent studies suggest that stretching interventions may contribute to long-term neuromuscular adaptation, enhancing both rehabilitation outcomes and athletic performance (Arntz et al., 2023; Behm & Chaouachi, 2011; Guissard & Duchateau, 2004).
Upper trapezius stretching has been shown to enhance cervical range of motion (ROM) and minimize compensatory movement patterns in patients experiencing unilateral neck pain (Gillani et al., 2020). Extended static stretching has been reported to significantly enhance muscle elasticity, reduce stiffness, and improve joint mobility (Takeuchi et al., 2021a). A study by Park et al. (2013) compared the immediate effects of upper trapezius stretching performed in a more tensed position (MTP) and a less tensed position (LTP) on cervical ROM in patients with unilateral neck pain. The results demonstrated that MTP stretching was significantly more effective than LTP stretching in increasing cervical ROM and reducing compensatory cervical extension at end-range rotation. While MTP stretching showed superior effects, recent studies have highlighted that stretching intensity, duration, and individual muscle responses are key factors influencing its effectiveness (Häkkinen et al., 2007; Park et al., 2013; Takeuchi et al., 2021a; Ylinen, 2007).
Among these factors, this study focuses on the intensity of stretching. As a preliminary investigation, this study aimed to examine how variations in stretching posture influence the intensity of the intervention before applying these methods to patients with neck pain or restricted cervical mobility. By maximizing the anatomical length of the muscle, the intensity can be increased, potentially leading to greater improvements in flexibility and neuromuscular adaptation. MTP stretching involves deep cervical flexion, ipsilateral rotation, and contralateral lateral bending, placing greater tension on the upper trapezius compared with conventional LTP stretching, which only involves contralateral lateral bending (Ylinen, 2007). Given that this study emphasizes stretching intensity as a key variable, MTP stretching provides a unique model for examining how increased tension influences neuromuscular adaptation.
However, despite its advantages, MTP stretching is limited in the application of cervical rotation. The KEMA approach, an advanced stretching technique developed by the KEMA Academy, utilizes maximal cervical rotation to enhance upper trapezius elongation and neuromuscular adaptation. Unlike MTP stretching, the KEMA approach maximizes cervical rotation, which may offer superior neuromuscular adaptation and upper trapezius elongation. Because cervical rotation plays a critical role in the effectiveness of upper trapezius stretching, a direct comparison between MTP stretching and the KEMA approach has, to our knowledge, not been systematically examined. Therefore, this study aims to compare MTP stretching with the KEMA approach, which incorporates maximal cervical rotation, to determine which method more effectively improves cervical ROM, reduces muscle stiffness, and increases pain threshold. By identifying the superior technique, this study seeks to refine clinical recommendations for managing upper trapezius hypertonicity and improving functional mobility in patients with neck dysfunction.
Ⅱ. Methods
1. Participants
This study recruited healthy adults in their 20s from B University in Busan who had no shoulder or neck discomfort and no history of trauma or surgery within the previous six months. Individuals with musculoskeletal or neurological disorders, or those who had visited a hospital within the previous three months, were excluded. Thirty-four participants who received an explanation of the study aims and procedures provided written informed consent and were randomly assigned to an experimental group (n= 17) or a control group (n= 17). The study protocol was approved by the Daegu University Institutional Review Board (1040621-202503-HR-024). The participants’ general characteristics are presented in Table 1.
Table 1. General characteristic of subjects
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
2. Measurement methods
1) MyotonPRO
The MyotonPRO (Myoton AS, Estonia) is a handheld device with high reliability and validity (Koterba & Saulicz, 2025). It delivers brief, low-force mechanical impulses via a lightweight probe to induce damped oscillations in the muscle, which are recorded with an accelerometer. On the dominant side upper trapezius, we measured muscle tone (frequency), stiffness, decrement, relaxation time, and creep (Li et al., 2024).
The measurement site was standardized to the mid-belly of the upper trapezius, operationalized as the midpoint of the distance from the C1~C7 spinous processes to the acromioclavicular joint. Participants adopted a comfortable supine position, and the probe was applied perpendicularly to the skin (Wendt & Waszak, 2024) (Fig 1). In automatic mode, three repeated measurements were obtained; the mean of the three trials was used for analysis. A 30s rest was provided between measurements.
Fig 1. MyotonPRO
2) Pressure pain threshold (PPT)
PPT (ZP-500N, BAOSHISHAN, China) over the upper trapezius was assessed using a digital algometer. With participants seated comfortably, the probe was placed on the mid-belly of the dominant upper trapezius, and pressure was increased at a constant rate until the participant verbally reported “pain,” at which point the value was recorded (Zamani et al., 2017) (Fig 2). Three trials were performed, the mean of the three values was analyzed, and a 30s rest was provided between trials.
Fig 2. PPT
3) Cervical range of motion (CROM)
CROM was measured using a CROM device (Performance Attainment Associates, Roseville, USA), which provides reliable and valid assessment of six movements: extension, flexion, bilateral rotation, and bilateral lateral flexion (Audette et al., 2010). A chair was positioned 1.5 m from a wall, and participants sat comfortably. To standardize the neutral (0 °) position, height-indexed targets were placed on the wall at eye level. With the CROM device fitted around the neck, cervical extension, contralateral lateral flexion, and ipsilateral rotation of the cervical spine corresponding to the dominant-side upper trapezius were each measured once per trial, for three trials total; the mean of three trials was analyzed (Fig 3). Post-intervention measurements were obtained using the same procedures. All measurement orders were randomized to minimize anticipation effects. A 30s rest was provided between all measurements.
Fig 3. CROM
3. Stretching intervention
Participants rested in a comfortable seated position beginning 5 minutes prior to pre-intervention assessment to stabilize baseline muscle tone. Ambient temperature, lighting, and noise were kept constant throughout testing. The stretching intensity in this study was established through modifications of the protocols described by Hanney et al. (2017) and Park et al. (2013), incorporating positional adjustments to account for variations in stretch loading across different postures.
Experimental group. To apply a higher-intensity stretch to the dominant-side upper trapezius, participants assumed a prone position and performed an ipsilateral cervical rotation stretch to the maximal available range. A 1.5 ㎝ support was placed under the zygomatic region to help maintain maximal rotation. The stretch was held for 30s, followed by 30s of rest in a prone, neutral head position supported by a cushion on the forehead. Four cycles were completed, after which participants rested supine for 3 min (Hanney et al., 2017; Magdič et al., 2025).
Control group. The control condition adopted the intervention described in a prior study (Park et al., 2013). Seated at the edge of a bed, participants lightly grasped the bed with the dominant hand and leaned the trunk toward the non-dominant side. They then performed contralateral lateral flexion, cervical flexion, and ipsilateral rotation, after which the non-dominant hand was placed on the occiput to apply a gentle overpressure. The stretch was held for 30s, followed by 30s of rest in a neutral seated position. Four cycles were completed, followed by a 3 min supine rest (Hanney et al., 2017) (Fig 4). The stretching interventions consisted of four cycles of 30s stretching followed by 30s rest, resulting in a total of 120s of stretching and 120s of rest. After completing all intervention cycles, participants rested comfortably in a supine position for 3 min before outcome measurements were initiated.
Fig 4. Stretching (a; experimental group, b; control group)
4. Statistical analysis
All analyses were performed using SPSS version 22.0 (IBM, Armonk, USA). Data are presented as mean±standard deviation. Normality was examined using the Shapiro–Wilk test (p>.05). Within-group pre-to-post changes were analyzed using paired t-tests. Between-group differences were examined using independent t-tests. The significance level was set at α= .05.
Ⅲ. Results
1. Upper trapezius muscle function according to stretching intensity
In the within-group comparisons (Table 2), the experimental group showed a significant change in frequency (p<.05), whereas the control group showed significant changes in frequency, stiffness, and relaxation time (p<.05). In the between-group comparisons (Table 3), none of the five MyotonPRO variables differed significantly between groups (p>.05).
Table 2. Within-group comparison using MyotonPRO measurements
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
Table 3. Between-group comparison of MyotonPRO measurements
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
2. Pressure pain threshold according to stretching intensity
In the within-group comparisons (Table 4), the control group demonstrated a significant change in PPT (p<.05). In the between-group comparisons (Table 5), no significant differences were observed (p>.05).
Table 4. Within-group comparison of pain measurements
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
Table 5. Between-group comparison of pain measurements
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
3. Cervical range of motion according to stretching intensity
In the within-group comparisons (Table 6), the experimental group exhibited significant increases in extension and ipsilateral rotation (p<.05), whereas the control group showed significant increases in extension, contralateral lateral flexion, and ipsilateral rotation (p<.05). In the between-group comparisons (Table 7), no significant differences were identified for any CROM variables (p>.05).
Table 6. Within-group comparison of cervical range of motion measurements (unit: °)
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
Table 7. Between-group comparison of cervical range of motion measurements (unit: °)
Experimental group; maximum rotation in prone position, control group; maximum rotation in sitting position
Ⅳ. Discussion
This study investigated the immediate effects of upper trapezius stretching intensity on muscle mechanical properties, pressure pain threshold, and cervical range of motion in healthy adults, as a preliminary step toward developing evidence-based clinical guidelines for patients with cervical mobility limitations.
Stretching is a widely applied clinical intervention intended to increase range of motion by influencing the elastic components of the muscle–tendon unit, neural factors, and connective tissue (Andrade et al., 2020; Behm et al., 2016; 2021b; Blazevich et al., 2014; Takeuchi et al., 2021b). In individuals with temporomandibular disorders, interventions including stretching reduced upper trapezius frequency by approximately 7.65 %, interpreted as post-intervention muscle relaxation (Magdič et al., 2025). Muscle relaxation is also accompanied by reductions in creep-that is, the progressive lengthening of muscle under sustained external load (Matsuo et al., 2025). Resistance training has been associated with decreased creep, whereas massage targeting relaxation has been associated with increased creep (Kablan et al., 2021). Magdič et al. (2025) further reported a 1.78 % increase in upper trapezius relaxation time following exercise. Increases in relaxation time indicate a longer return to the structural baseline (Park & Hwang, 2024), suggesting that exercise interventions including stretching may promote upper trapezius relaxation. In another study, ischemic compression for pain reduction in the gastrocnemius increased both range of motion and relaxation time (Pérez-Bellmunt et al., 2022), implying that trigger-point–focused interventions can alter biomechanical and viscoelastic muscle properties (Magdič et al., 2025).
In the present study, within-group MyotonPRO comparisons of the upper trapezius showed a significant decrease in frequency in the experimental group (-0.30±0.41 ㎐, p<.05). In the control group, frequency (-0.26±0.40 ㎐), stiffness (-7.43±12.32 N/m), and relaxation time (0.83±1.14 ㎳) changed significantly (p<.05). These findings likely reflect muscle relaxation induced by upper trapezius stretching and consequent alterations in biomechanical and viscoelastic properties.
In healthy adults, high-intensity stretching of the biceps femoris increased knee range of motion by 11.2 % (≈14 °) and musculotendinous length by 13.7 % (≈12 ㎜) (Freitas & Mil-Homens, 2015). Such effects have been attributed not to direct changes in contractile force production, but to mechanotransduction-driven modifications in the physiological, structural, and contractile behavior of muscle fibers via cellular signaling and gene expression (Panidi et al., 2023). In our CROM analysis, the experimental group showed significant increases in extension (4.43±6.05 °) and ipsilateral rotation (6.24±6.29 °) (p<.05), while the control group showed significant increases in extension (3.14±4.85 °), contralateral lateral flexion (3.33±4.61 °), and ipsilateral rotation (5.96±5.17 °) (p<.05). These results suggest that both stretching protocols likely modified upper trapezius muscle–tendon unit flexibility, connective tissue behavior, and contractile properties. Matsuo et al. (2025) reported that a 30s stretch is sufficient to relax and elongate the viscoelastic elements of the muscle–tendon unit, a phenomenon referred to as creep. In this context, the sustained force applied during stretching may increase range of motion safely by lengthening muscle without placing additional stress on the joint capsule (Núñez et al., 2023). In individuals with unilateral neck pain characterized by increased passive tension and shortened muscle length in the upper trapezius, even brief interventions–when applied with the muscle held at a lengthened position–reduced passive tension, preserved optimal actin–myosin alignment, and increased sarcomere number, thereby improving cervical range of motion, particularly in the experimental condition (Park et al., 2013).
In participants with myofascial pain, stretching of the upper trapezius and levator scapulae produced significant immediate and 2-h changes in tenderness (Mansoori et al., 2020). This has been attributed to reduced pain perception via acute ischemic compression occurring during stretching (Hanten et al., 2000). In our study, only the control group showed a significant PPT increase (0.56±0.85 ㎏, p<.05), although the experimental group also exhibited a numerical increase (0.72±1.41 ㎏). These findings likely reflect decreased pain perception secondary to altered local blood flow during stretching. In an immediate-effects comparison of high-velocity low-amplitude thrust to the cervical/thoracic spine versus upper trapezius stretching in healthy adults, PPT increased significantly in the left upper trapezius in both groups, and the stretching group also improved on the right side. CROM increased significantly for left lateral flexion in both groups (Hanney et al., 2017). A meta-analysis of 19 studies (n= 467) reported that, in healthy individuals, static stretching produced minimal increases in resting muscle length but small increases in muscle length during stretching (Panidi et al., 2023). Although short-term significance is not consistently demonstrated, multiple studies suggest that immediate post-stretch changes in range of motion or pain threshold may reflect increased psychosomatic tolerance to stretch-induced discomfort (Honoré et al., 2018; Lemeunier et al., 2018; Walton et al., 2011).
The most salient finding of the present study is that no between-group differences were observed for MyotonPRO variables, PPT, or CROM. Practically, this suggests that, when stretching the upper trapezius, a prone position focusing on ipsilateral head rotation to emphasize the target muscle (experimental condition) may yield effects comparable to a seated protocol combining contralateral lateral flexion, ipsilateral rotation, and cervical flexion with gentle overpressure (control condition). However, both groups consisted of healthy adults with relatively low passive tension and minimal baseline shortening of the upper trapezius. The absence of between-group differences may therefore relate to the “immediate-effect” paradigm, as well as to the specific dose (time and intensity) used.
In sum, time under stretch should be considered when aiming to induce morphological change (Behm et al., 2021a). Given the healthy sample, adjustments to stretching volume and intensity may also be warranted (Moltubakk et al., 2021). Generalizability is limited for three reasons: (1) a modest sample of healthy adults; (2) the lack of systematic control over stretching volume or duration, as well as the absence of objective assessment through electromyographic activity or muscle length measurements; and (3) a short intervention period focusing solely on acute neuromuscular responses. Addressing these limitations in future work may enable a more objective delineation of how stretching intensity influences upper trapezius MyotonPRO parameters, pain, and cervical range of motion.
Ⅴ. Conclusion
Based on the present findings, a rotation-focused upper trapezius stretch performed in the prone position produced immediate effects comparable to those achieved with a conventional stretch intended to place the muscle in its most lengthened position. Clinically, when individuals cannot assume the position that maximally lengthens the upper trapezius, a rotation-focused stretch may provide a reasonable alternative for eliciting similar immediate responses in healthy adults. Therefore, based on this preliminary study, further research is warranted to determine effective stretching approaches in individuals with cervical pain or mobility limitations.
References
- Andrade RJ, Freitas SR, Hug F, et al(2020). Chronic effects of muscle and nerve-directed stretching on tissue mechanics. J Appl Physiol (1985), 129(5), 1011-1023. DOI: 10.1152/japplphysiol.00239.2019
- Arntz F, Markov A, Behm DG, et al(2023). Chronic effects of static stretching exercises on muscle strength and power in healthy individuals across the lifespan: a systematic review with multi-level meta-analysis. Sports Med, 53(3), 723-745. DOI: 10.1007/s40279-022-01806-9
- Audette I, Dumas JP, Côté JN, et al(2010). Validity and between-day reliability of the cervical range of motion (CROM) device. J Orthop Sports Phys Ther, 40(5), 318-323. DOI: 10.2519/jospt.2010.3180
- Behm DG, Alizadeh S, Anvar SH, et al(2021a). Non-local acute passive stretching effects on range of motion in healthy adults: a systematic review with meta-analysis. Sports Med, 51(5), 945-959. DOI: 10.1007/s40279-020-01422-5
- Behm DG, Blazevich AJ, Kay AD, et al(2016). Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab, 41(1), 1-11. DOI: 10.1139/apnm-2015-0235
- Behm DG, Chaouachi A(2011). A review of the acute effects of static and dynamic stretching on performance. Eur J Appl Physiol, 111(11), 2633-2651. DOI: 10.1007/s00421-011-1879-2
- Behm DG, Kay AD, Trajano GS(2021b). Effects of stretching on injury risk reduction and balance. J Clin Exerc Physiol, 10(3), 106–116. DOI: 10.31189/2165-6193-10.3.106
- Blazevich AJ, Cannavan D, Waugh CM, et al(2014). Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans. J Appl Physiol (1985), 117(5), 452-462. DOI: 10.1152/japplphysiol.00204.2014
- Cai P, Liu L, Li H(2023). Dynamic and static stretching on hamstring flexibility and stiffness: a systematic review and meta-analysis. Heliyon, 9(8), Printed Online. DOI: 10.1016/j.heliyon.2023.e18795
- Camargo PR, Neumann DA(2019). Kinesiologic considerations for targeting activation of scapulothoracic muscles–part 2: trapezius. Braz J Phys Ther, 23(6), 467-475. DOI: 10.1016/j.bjpt.2019.01.011
- Freitas SR, Mendes B, Sant GL, et al(2018). Can chronic stretching change the muscle‐tendon mechanical properties? a review. Scand J Med Sci Sports, 28(3), 794-806. DOI: 10.1111/sms.12957
- Freitas SR, Mil-Homens P(2015). Effect of 8-week high-intensity stretching training on biceps femoris architecture. J Strength Cond Res, 29(6), 1737-1740. DOI: 10.1519/JSC.0000000000000800
- Fukaya T, Sato S, Yahata K, et al(2022). Effects of stretching intensity on range of motion and muscle stiffness: a narrative review. J Bodyw Mov Ther, 32, 68-76. DOI: 10.1016/j.jbmt.2022.04.011
- Gillani SN, Rehman SU, Masood T, et al(2020). Effects of eccentric muscle energy technique versus static stretching exercises in the management of cervical dysfunction in upper cross syndrome: a randomized control trial. J Pak Med Assoc, 70(3), 394-398. DOI: 10.5455/JPMA.300417
- Guissard N, Duchateau J(2004). Effect of static stretch training on neural and mechanical properties of the human plantar‐flexor muscles. Muscle Nerve, 29(2), 248-255. DOI: 10.1002/mus.10549
- Häkkinen A, Salo P, Tarvainen U, et al(2007). Effect of manual therapy and stretching on neck muscle strength and mobility in chronic neck pain. J Rehabil Med, 39(7), 575-579. DOI: 10.2340/16501977-0094
- Hanney WJ, Puentedura EJ, Kolber MJ, et al(2017). The immediate effects of manual stretching and cervicothoracic junction manipulation on cervical range of motion and upper trapezius pressure pain thresholds. J Back Musculoskelet Rehabil, 30(5), 1005-1013. DOI: 10.3233/BMR-169573
- Hanten WP, Olson SL, Butts NL, et al(2000). Effectiveness of a home program of ischemic pressure followed by sus- tained stretch for treatment of myofascial trigger points. Phys Ther, 80(10), 997–1003.
- Honoré M, Leboeuf-Yde C, Gagey O(2018). The regional effect of spinal manipulation on the pressure pain threshold in asymptomatic subjects: a systematic literature review. Chiropr Man Therap, 26, Printed Online. DOI: 10.1186/s12998-018-0181-3
- Huang LL, Huang TS, Lin YH, et al(2022). Effects of upper trapezius myofascial trigger points on scapular kinematics and muscle activation in overhead athletes. J Hum Kinet, 84, 32-42. DOI: 10.2478/hukin-2022-000079
- Kablan N, Alaca N, Tatar Y(2021). Comparison of the immediate effect of petrissage massage and manual lymph drainage following exercise on biomechanical and viscoelastic properties of the rectus femoris muscle in women. J Sport Rehabil, 30(5), 725–730. DOI: 10.1123/jsr.2020-0276
- Kawabuchi K, Yamane K, Maniwa S, et al(2024). Epimuscular myofascial force transmission between the levator scapulae muscle and the upper fiber of the serratus anterior or rhomboid minor muscles. Clin Biomech, 112, Printed Online. DOI: 10.1016/j.clinbiomech.2024.106194
- Ko MG, Jeun YJ(2020). The effect of stretching to muscle stiffness in hospital office employees. Journal of the Korea Society of Computer and Information, 25(1), 125-130. DOI: 10.9708/jksci.2020.25.01.125
- Koterba J, Saulicz E(2025). Reliability of measurement of neck and back muscle mechanical properties using MyotonPRO: a systematic review. J Bodyw Mov Ther, 44, 616-624.
- Lemeunier N, Jeoun EB, Suri M, et al(2018). Reliability and validity of clinical tests to assess posture, pain location, and cervical spine mobility in adults with neck pain and its associated disorders: Part 4. a systematic review from the cervical assessment and diagnosis research evaluation (CADRE) collaboration. Musculoskelet Sci Pract, 38, 128-147. DOI: 10.1016/j.msksp.2018.09.013
- Li G, Liu D, Yang D, et al(2024). The impact of different muscle relaxation techniques on the upper trapezius and its relationship with the middle trapezius. J Physiol Investig, 67(4), 225-232. DOI: 10.4103/ejpi.EJPI-D-24-00041
- Magdič M, Kalc M, Vogrin M(2025). Acute myotonometric changes in the masseter and upper trapezius muscles after upper body quarter stretching and coordination exercises or chewing. Appl Sci, 15(1), Printed Online. DOI: 10.3390/app15010344
- Mansoori SS, Moustafa IM, Ahbouch A, et al(2020). Optimal duration of stretching exercise in patients with chronic myofascial pain syndrome: a randomized controlled trial. J Rehabil Med, 53(1), Printed Online. DOI: 10.2340/16501977-2781
- Matsuo S, Takeuchi K, Nakamura M, et al(2025). Acute effects of dynamic and ballistic stretching on flexibility: a systematic review and meta-analysis. J Sports Sci Med, 24(2), 463-474. DOI: 10.52082/jssm.2025.463
- Moltubakk MM, Villars FO, Magulas MM, et al(2021). Altered triceps surae muscle-tendon unit properties after six months of static stretching. Med Sci Sports Exerc, 53(9), 1975–1986. DOI: 10.1249/MSS.0000000000002671
- Núñez FJ, Martínez JC, Overberg JA, et al(2023). Hamstring muscle architecture and myotonometer measurements in elite professional football players with a prior strained hamstring. Biol Sport, 40(1), 93-101. DOI: 10.5114/biolsport.2023.112092
- Panidi I, Donti O, Konrad A, et al(2023). Muscle architecture adaptations to static stretching training: a systematic review with meta-analysis. Sports Med Open, 9(1), Printed Online. DOI: 10.1186/s40798-023-00591-7
- Park HK, Hwang BH(2024). Immediate effects of hamstring exercises using a reformer, sling, and foam roller on knee joint angles and MyotonPRO measurements in healthy adults in their 20s. J Korean Soc Integr Med, 12(4), 147-158. DOI: 10.15268/ksim.2024.12.4.147
- Park KN, Ha SM, Kim SH, et al(2013). Immediate effects of upper trapezius stretching in more and less tensed positions on the range of neck rotation in patients with unilateral neck pain. Phys Ther Korea, 20(1), 47-54. DOI: 10.12674/ptk.2013.20.1.047
- Pérez-Bellmunt A, Simon M, López-de-Celis C, et al (2022). Effects on neuromuscular function after ischemic compression in latent trigger points in the gastrocnemius muscles: a randomized within-participant clinical trial. J Manipulative Physiol Ther, 45(7), 490–496. DOI: 10.1016/j.jmpt.2020.07.015
- Sasaki K, Miyamoto N(2024). Intramuscular stiffness distribution in anterior and posterior upper trapezius muscles in healthy young males. Front Sports Act Living, 6, Printed Online. DOI: 10.3389/fspor.2024.1507207
- Takeuchi K, Akizuki K, Nakamura M(2021a). Time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching. Plos One, 16(9), Printed Online. DOI: 10.1371/journal.pone.0257367
- Takeuchi K, Sato S, Kiyono R, et al(2021b). High-intensity static stretching in quadriceps is affected more by its intensity than its duration. Front Physiol, 12, Printed Online. DOI: 10.3389/fphys.2021.709655
- Taş S, Korkusuz F, Erden Z(2018). Neck muscle stiffness in participants with and without chronic neck pain: a shear-wave elastography study. J Manipulative Physiol Ther, 41(7), 580-588. DOI: 10.1016/j.jmpt.2018.01.007
- Umair A, Ghafoor I, Malik S, et al(2024). Effectiveness of manual compression and stretching for the myofascial trigger points in upper trapezius and levator scapulae in office workers. J Health Rehabil Res, 4(2), 1301-1306. DOI: 10.61919/jhrr.v4i2.1082
- Walton D, MacDermid J, Nielson W, et al(2011). A descriptive study of pressure pain threshold at 2 standardized sites in people with acute or subacute neck pain. J Orthop Sports Phys Ther, 41(9), 651-657. DOI:10.2519/jospt.2011.3667
- Wendt M, Waszak M(2024). Assessment of the stiffness of the upper trapezius muscle in a group of asymptomatic people with cervical spine rotation asymmetry. PLoS One, 19(2), Printed Online. DOI: 10.1371/journal.pone.0298544
- Ylinen J(2007). Physical exercises and functional rehabilitation for the management of chronic neck pain. Eura Medicophys, 43(1), 119-132.
- Zamani S, Okhovatian F, Naimi SS, et al(2017). Intra-examiner and between-day reliability of algometer for pressure pain threshold and pain sensitivity in upper trapezius muscle in asymptomatic young adult women. Journal of Clinical Physiotherapy Research, 2(1), 15-20.