Acute and Prolonged Effects of Stretching on Shear Modulus of the Pectoralis Minor Muscle

Abstract

Increased muscle stiffness of the pectoralis minor (PMi) could deteriorate shoulder function. Stretching is useful for maintaining and improving muscle stiffness in rehabilitation and sport practice. However, the acute and prolonged effect of stretching on the PMi muscle stiffness is unclear due to limited methodology for assessing individual muscle stiffness. Using shear wave elastography, we explored the responses of shear modulus to stretching in the PMi over time. The first experiment (n = 20) aimed to clarify the acute change in the shear modulus during stretching. The shear modulus was measured at intervals of 30 s × 10 sets. The second experiment (n = 16) aimed to observe and compare the prolonged effect of different durations of stretching on the shear modulus. Short and long stretching duration groups underwent 30s × 1 set and 30s × 10 sets, respectively. The assessments of shear modulus were conducted before, immediately after, and at 5, 10, and 15 min post-stretching. In experiment I, the shear modulus decreased immediately after a bout (30 s) of stretching (p < 0.001, change: -2.3 kPa, effect size: r = 0.72) and further decreased after 3 repetitions (i.e., 90 s) of stretching (p = 0.03, change: -1.0 kPa, effect size: r = 0.53). In experiment II, the change in the shear modulus after stretching was greater in the long duration group than in the short duration group (p = 0.013, group mean difference: -2.5 kPa, partial η2 = 0.36). The shear modulus of PMi decreased immediately after stretching, and stretching for a long duration was promising to maintain the decreased shear modulus. The acute and prolonged effects on the PMi shear modulus provide information relevant to minimum and persistent stretching time in rehabilitation and sport practice.

Local and Non-local Effects of Foam Rolling on Passive Soft Tissue Properties and Spinal Excitability

“…Shear elastic modulus of MG was measured by means of an ultrasonic shear wave elastography (SWE) imaging device (Aixplorer SuperSonic Imagine, Aix-en-Provence, France) with a linear probe (4-15 MHz, SuperLinear 15-4, Vermon, Tours, France) and using the SWE mode (musculoskeletal preset, penetration mode, smoothing level 5, persistence medium). SWE provides a two-dimensional map of the shear elastic modulus on the B-mode image of the target tissue at 1 Hz with a spatial resolution of 1 × 1 mm (Lacourpaille et al, 2012;Umehara et al, 2021). Measurements were obtained at a neutral ankle position and 20 • plantar flexion, which is similar to the positions of DF ROM measurements.…”

Effect of chest mobilization on intercostal muscle stiffness

“…During the procedure, we checked whether the participant was in pain and took care to avoid any pain. Based on previous studies on stretching of the skeletal muscles of the extremities ( Taniguchi et al, 2015 ; Umehara et al, 2021 ), one set was performed 10 times in 1 min for a total of 5 sets, with rest of approximately 10 s the between sets. Stretching techniques were performed by one physical therapist (licensed certified therapist of respiration in Japan) with four years of respiratory physiotherapy experience.…”

The effects of eccentric exercise on passive hamstring muscle stiffness: Comparison of shear-wave elastography and passive knee torque outcomes

“…Static stretching has been shown to decrease both passive joint torque and muscle shear modulus, and the magnitude of the effect seem to be dependent on factors such as intensity and volume of the stretching. 15 , 16 However, while dynamic stretching also decreases passive joint torque, 17 it seems to increase the muscle shear modulus. 14 While further studies are needed to clarify this difference, caution should be taken when comparing the assessments of both passive joint torque and muscle shear modulus after stretching interventions.…”