Semimembranosus muscle displacement is associated with movement of the superficial fascia: An in vivo ultrasound investigation

Is thoracolumbar fascia shear-wave modulus affected by active and passive knee flexion?

The purpose of this study was to examine the effect of passive and active knee flexion efforts on the stiffness of the thoracolumbar (TLF), semitendinosus (STF), and semimembranosus fascia (SMF). Fourteen young healthy males participated in this study. Using ultrasound shear-wave elastography, fascia elastic modulus was measured at rest (passive condition) and during submaximal isometric knee flexion efforts (active condition) with the hip at neutral position and the knee flexed at 0°, 45°, and 90°. Analysis of variance designs indicated that when the knee was passively extended from 90° to 0°, shear modulus of the TLF, SMF, and STF increased significantly (p < 0.05). Similarly, active knee flexion contractions caused a significant increase in TLF, SMF, and STF shear modulus (p < 0.001). Compared to hamstring fascia, the TLF showed greater thickness but a lower shear modulus (p < 0.05) while STF modulus was greater compared that to SMF during active contraction (p < 0.05). These results indicate that exercising the hamstring muscles can remotely influence the stiffness of the fascia which surrounds the lumbar area.

Epimuscular myofascial force transmission between the levator scapulae muscle and the upper fiber of the serratus anterior or rhomboid minor muscles

BACKGROUND

This study investigated the epimuscular myofascial force transmission between the levator scapulae, serratus anterior, and rhomboid minor muscles.

METHODS

The participants included 10 healthy males (a total of 20 shoulders). Differences in the shear moduli of the levator scapulae, serratus anterior, and rhomboid minor muscles were measured in the resting and levator scapulae stretching positions using shear wave elastography. The correlation between the rates of change for each muscle was also verified.

FINDINGS

The results demonstrated a notable increase in the shear modulus from the resting to stretching positions for levator scapulae (42.9 ± 17.6 kPa vs. 52.4 ± 15.2 kPa) and serratus anterior (32.8 ± 12.9 kPa vs. 58.4 ± 18.5 kPa) (P = 0.02, P < 0.01). However, there was no significant difference in the shear modulus for the rhomboid minor between the resting (44.0 ± 19.2 kPa) and stretching (41.0 ± 20.2 kPa) positions (P = 0.40). Moreover, a significant positive correlation was observed between rates of change for the levator scapulae and serratus anterior muscles (P = 0.04, r = 0.459).

INTERPRETATION

These findings indicate that the shear modulus of the serratus anterior increased with the stretching of the levator scapulae, suggesting the occurrence of epimuscular myofascial force transmission between these two muscles with different muscle insertions.

Soleus muscle and Achilles tendon compressive stiffness is related to knee and ankle positioning

Changes in fascicle length and tension of the soleus (SOL) muscle have been observed in humans using B-mode ultrasound to examine the knee from different angles. An alternative technique of assessing muscle and tendon stiffness is myometry, which is non-invasive, accessible, and easy to use. This study aimed to estimate the compressive stiffness of the distal SOL and Achilles tendon (AT) using myometry in various knee and ankle joint positions. Twenty-six healthy young males were recruited. The Myoton-PRO device was used to measure the compressive stiffness of the distal SOL and AT in the dominant leg. The knee was measured in two positions (90° of flexion and 0° of flexion) and the ankle joint in three positions (10° of dorsiflexion, neutral position, and 30° of plantar flexion) in random order. A three-way repeated-measures ANOVA test was performed. Significant interactions were found for structure × ankle position, structure × knee position, and structure × ankle position × knee position (p < 0.05). The AT and SOL showed significant increases in compressive stiffness with knee extension over knee flexion for all tested ankle positions (p < 0.05). Changes in stiffness relating to knee positioning were larger in the SOL than in the AT (p < 0.05). These results indicate that knee extension increases the compressive stiffness of the distal SOL and AT under various ankle joint positions, with a greater degree of change observed for the SOL. This study highlights the relevance of knee position in passive stiffness of the SOL and AT.

Gender difference in effects of proprioceptive neuromuscular facilitation stretching on flexibility and stiffness of hamstring muscle

Objective: This study investigated the acute effects of PNF stretching on hamstring flexibility and muscle stiffness of lower limbs between genders.

Methods: 15 male and 15 female university students without any injury histories on lower limbs in the past 3 months were included in this study were selected. All subjects were measured by MyotonPRO before and after stretching to determine the muscle stiffness of the biceps femoris muscle (BF), semitendinosus muscle (ST) of the hamstring and the medial gastrocnemius muscles (MG), lateral gastrocnemius muscles (LG), and the soleus (SOL) of the triceps surae muscles. Additionally, their flexibility was measured using the sit-and-reach test (the SR test) and passive hip range of motion (ROM). Differences based on time (pre-stretching vs. post-stretching) and sex (females vs. males) were assessed using 2 × 2 repeated measures AVONA.

Results: There was a significant decrease in the stiffness of the hamstring and triceps surae muscles after stretching (BF, MG, LG, and SOL: p < 0.001; ST: p = 0.003). The muscle stiffness of the hamstring and triceps surae muscles is larger in males than in females at all time points (p < 0.001). There was a significant increase in hip flexion angle and the SR test in males and females after PNF stretching (p < 0.001); However, there was no difference in the change in the muscle stiffness and the flexibility between genders (p > 0.05).

Conclusion: PNF stretching helped improve hamstring flexibility and decrease muscle stiffness. Stretching the hamstrings can also contribute to a decrease in the stiffness of the triceps surae muscles. The muscle stiffness of males before and after stretching is always greater than that of females. However, there was no difference in the change of improvement in stretching between genders.

Keeping It Local in Metabolic Disease: Adipose Tissue Paracrine Signaling and Insulin Resistance

Alterations in adipose tissue composition and function are associated with obesity and contribute to the development of type 2 diabetes. While the significance of this relationship has been cemented, our understanding of the multifaceted role of adipose tissue in metabolic heath and disease continues to evolve and expand. Heterogenous populations of cells that make up adipose tissue throughout the body generate diverse secretomes containing a mosaic of bioactive compounds with vast structural and signaling capabilities. While there are many reports highlighting the important role of adipose tissue endocrine signaling in insulin resistance and type 2 diabetes, the direct, local, paracrine effect of adipose tissue has received less attention. Recent studies have begun to underscore the importance of considering anatomically discrete adipose depots for their specific impact on local microenvironments and metabolic function in neighboring tissues as well as regulation of whole-body physiology. This article highlights the important role of adipose tissue paracrine signaling on metabolic function and insulin sensitivity in nearby tissues and organs, specifically focusing on visceral, pancreatic, subcutaneous, intermuscular, and perivascular adipose tissue depots.

Semimembranosus muscle displacement is associated with movement of the superficial fascia: An in vivo ultrasound investigation

The deep fascia enveloping the skeletal muscle has been shown to contribute to the mechanics of the locomotor system. However, less is known about the role of the superficial fascia (SF). This study aimed to describe the potential interaction between the Hamstring muscles and the SF. Local movement of the dorsal thigh's soft tissue was imposed making use of myofascial force transmission effects across the knee joint: In eleven healthy individuals (26.8 ± 4.3 years, six males), an isokinetic dynamometer moved the ankle into maximal passive dorsal extension (knee extended). Due to the morphological continuity between the gastrocnemius and the Hamstrings, stretching the calf led to soft tissue displacements in the dorsal thigh. Ultrasound recordings were made to dynamically visualize (a) the semimembranosus muscle and (b) the superficial fascia. Differences in and associations between horizontal movement amplitudes of the two structures, quantified via cross-correlation analyses, were calculated by means of the Mann-Whitney U test and Kendal's tau test, respectively. Mean horizontal movement was significantly higher in the muscle (5.70 mm) than in the SF (0.72 mm, p < 0.001, r = 0.82). However, a strong correlation between the tissue displacements in both locations was detected (p < 0.001, r = 0.91). A Direct mechanical relationship may exist between the SF and the skeletal muscle. Deep pathologies or altered muscle stiffness could thus have long-term consequences for rather superficial structures and vice versa.