Time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching

Objectives The purpose of this study was to examine the time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching. Methods Fourteen healthy men (20.9 ± 0.7 years, 169.1 ± 7.5cm, 61.6 ± 6.5kg) received static stretching for 60 seconds at two different intensities based on the point of discomfort (100%POD and 120%POD) of each participant, in random order. To evaluate the time course of changes in the flexibility of the hamstrings, the knee extension range of motion (ROM), passive torque at end ROM, and muscle-tendon unit stiffness were measured pre-stretching, post-stretching, and at both 10 and 20 minutes after static stretching. Results For both intensities, ROM and passive torque at pre-stretching were significantly smaller than those at post-stretching (p < 0.01 in both intensities), 10 minutes (p < 0.01 in both intensities), and 20 minutes (p < 0.01 in both intensities). The muscle-tendon unit stiffness at pre-stretching was significantly higher than that at post-stretching (p < 0.01), 10 minutes (p < 0.01), and 20 minutes (p < 0.01) only in the 120%POD, but it showed no change in the 100%POD. Conclusion The results showed that ROM and passive torque increased in both intensities, and the effects continued for at least 20 minutes after stretching regardless of stretching intensity. However, the muscle-tendon unit stiffness of the hamstrings decreased only after static stretching at the intensity of 120%POD, and the effects continued for at least 20 minutes after stretching.

High-Intensity Static Stretching in Quadriceps Is Affected More by Its Intensity Than Its Duration

A previous study reported that 3-min of high-intensity static stretching at an intensity of 120% of range of motion (ROM) did not change the muscle stiffness of the rectus femoris, because of the overly high stress of the stretching. The purpose of this study was to examine the effects of high-intensity static stretching of a shorter duration or lower intensity on the flexibility of the rectus femoris than that of the previous study. Two experiments were conducted (Experiment 1 and 2). In Experiment 1, eleven healthy men underwent static stretching at the intensity of 120% of ROM for two different durations (1 and 3 min). In Experiment 2, fifteen healthy men underwent 3-min of static stretching at the intensity of 110% of ROM. The shear elastic modulus of the quadriceps were measured. In Experiment 1, ROM increased in both interventions (p &lt; 0.01), but the shear elastic modulus of the rectus femoris was not changed. In Experiment 2, ROM significantly increased (p &lt; 0.01), and the shear elastic modulus of the rectus femoris significantly decreased (p &lt; 0.05). It was suggested that the stretching intensity (110%) is more important than stretching duration to decrease the muscle stiffness of the rectus femoris.

The Relationship between Stretching Intensity and Changes in Passive Properties of Gastrocnemius Muscle-Tendon Unit after Static Stretching

This study aimed to investigate the relationship between relative or absolute intensity and changes in range of motion and passive stiffness after static stretching. A total of 65 healthy young adults voluntarily participated in this study and performed static stretching of the plantar flexor-muscle for 120 s. Dorsiflexion range of motion and passive torque during passive dorsiflexion before and after stretching were assessed. We measured the passive torque at a given angle when the minimum angle was recorded before and after stretching. The angle during stretching was defined as the absolute intensity. Dorsiflexion range of motion before stretching was defined as 100%, and the ratio (%) of the angle during stretching was defined as the relative intensity. A significant correlation was found between absolute intensity and change in passive torque at a given angle (r = −0.342), but relative intensity and range of motion (r = 0.444) and passive torque at dorsiflexion range of motion (r = 0.259). A higher absolute intensity of stretching might be effective in changing the passive properties of the muscle-tendon unit. In contrast, a higher relative intensity might be effective in changing the range of motion, which could be contributed by stretch tolerance.

FT-IR Spectroscopic Characteristics of Ganoderma lucidum Secondary Metabolites

Ganoderma lucidum is an important medicinal mushroom widely used in pharmaceuticals for their antiviral, antibacterial, antifungal, anticancer and immunoregulatory properties and also used in agriculture as an antiviral and antibacterial agent. Fourier Transform Infrared (FT-IR) spectroscopy is a tool widely used in the researches for the identification of organic compounds in the organism. In our study, we used FT-IR Spectroscopy for determination the chemical nature of Ganoderma lucidum, and their standards Squalene and Ganoderic acid A. In the FT-IR spectrum for the G. lucidum obtained in the region of 3782.69 cm-1 to 568.898 cm-1 the absorptions peak represents the alcohols, halogens, silicon and phosphorus groups present in the sample. In the squalene standard, ketones, amides, and guanidine, nitrile and azine stretches were found in the wavelength 1655-1550 cm-1. In the Ganoderic acid A sulfur compounds with weak stretching intensity were obtained in the wavelength 500-400 cm-1. We have concluded that FT-IR spectroscopy is an effective method to analyze the chemical nature of the organic groups present in the samples.

Static Stretching Intensity Does Not Influence Acute Range of Motion, Passive Torque, and Muscle Architecture

Context: Although stretching exercises are commonly used in clinical and athletic practice, there is a lack of evidence regarding the methodological variables that guide the prescription of stretching programs, such as intensity. Objective: To investigate the acute effects of different stretching intensities on the range of motion (ROM), passive torque, and muscle architecture. Design: Two-group pretest–posttest design. Setting: Laboratory. Participants: Twenty untrained men were allocated into the low- or high-intensity group. Main Outcome Measures: Subjects were evaluated for initial (ROMinitial) and maximum (ROMmax) discomfort angle, stiffness, viscoelastic stress relaxation, muscle fascicle length, and pennation angle. Results: The ROM assessments showed significant changes, in both groups, in the preintervention and postintervention measures both for the ROMinitial (P < .01) and ROMmax angle (P = .02). There were no significant differences for stiffness and viscoelastic stress relaxation variables. The pennation angle and muscle fascicle length were different between the groups, but there was no significant interaction. Conclusion: Performing stretching exercises at high or low intensity acutely promotes similar gains in flexibility, that is, there are short-term/immediate gains in ROM but does not modify passive torque and muscle architecture.

Analysis of Woven Fabric at the Place of the Sewn Seam

Key importance and the role of sewn seam in the woven fabric are presented. Fabric properties in the places joined with the sewn seam on which garment durability, applicability, appearance and quality depend are highlighted. Seam location is usually the weakest spot on the garment, especially when the great loads are present at these places. Mechanical properties of the sewn fabrics were investigated in different test conditions. The influence of the load on the sewn seam is analyzed in time intervals. Sample with seam have approximately 70% lower breaking properties (breaking force and elongation at break) than the sample without seam. By preloading the seam fabrics with 30%, 50% and 70% of elongation at break, for a 3-h period, the effect on mechanical properties were tested and the differences in pre-stretching intensity were observed. By conducting such test, it is expected that the fabric experience further degradation and that breaking properties further reduce, but the exact opposite occurred (breaking properties, by increasing the preload, increase even more), because of various material properties (structural fabric properties, raw material characteristics, seam characteristics).

Role of polydimethylsiloxane in properties of ternary materials based on polyimides containing zeolite Y

Mixed matrix materials, containing poly(dimethylsiloxane), phosphine oxide-based polyimide, and zeolite Y were prepared by means of blending hybridisation. The thermal stability of the materials and the hydrophobic properties were enhanced. The decrease in the glass transition temperature of the materials with the increase in poly(dimethylsiloxane) content supported the polymer-chain flexibility. The pristine polyimide and the zeolite-filled polyimide exhibited the highest transparency. Fourier transform infrared (FTIR) spectroscopy confirmed that the increase in the amount of the lowest molecular mass poly(dimethylsiloxane) ingredient indicated strong alkyl and Si—O—Si stretching modes, whilst the alkyl and Si—O—Si stretching intensity decreased in the presence of the highest amount of and the highest molecular mass poly(dimethylsiloxane). The hydrophobic poly(dimethylsiloxane) moiety created an inverse relationship between the porosity of the materials (surface roughness) and the hydrophilicity. The nanocrystallite domain, identified by X-ray diffraction analysis (XRD) and possessing an exotherm crystallisation peak, occurred in the lowest amount of poly(dimethylsiloxane) with the highest molecular mass-based hybrid material. The nanocrystallite enhanced the storage modulus as determined by the dynamic mechanical analyser (DMA). The nanocrystalline formation resulted in a slight increase in the alkyl stretching and the Si—O—Si stretching of the lowest amount of and the highest molecular mass poly(dimethylsiloxane)-containing material over those of the lowest molecular mass poly(dimethylsiloxane) in the same amounts of material involved.