Effects of repeated isometric and eccentric contractions on active muscle stiffness.

Background: Joint stiffness endurance is considered essential in many sports events. We previously reported that reduced joint stiffness due to repetitive hopping was associated with reduced active muscle stiffness. However, the determinants of active muscle stiffness endurance were unknown.

Influence of preconditioning on morphological and mechanical properties of human Achilles tendon in vivo.

The present study aimed 1) to verify whether the effect of preconditioning was observed in the measured variables during the measurement of the human tendon in vivo (i.e., repeated contractions with breaks between trials) and 2) to determine the changes in tendon properties and their mechanisms due to submaximal repetitive contractions.

Effects of Static Stretching on the Blood Circulation of Human Tendon In Vivo.

The purpose of this study is to compare the effects of 2- and 5 min of static stretching protocols on the changes in blood circulation of tendon (as well as muscle) and heart rate. Twelve healthy males (age: 26.2 ± 9.

Effects of muscular endurance and tendon extensibility on endurance of joint stiffness.

In some sporting events (e.g., long-distance running), the ability to maintain joint stiffness is considered an essential physical ability.

Effects of tendon elastic energy and electromyographic activity pattern on jumping height and pre-stretch augmentation during jumps with different pre-stretch intensity.

The present study aimed to investigate the effects of tendon elastic energy and electromyographic activity patterns (ratio of pre-landing to concentric: mEMG PLA/CON; ratio of eccentric to concentric; mEMG ECC/CON) on jump performance. Twenty-nine males performed five kinds of unilateral jumps using only ankle joint (no-countermovement jump: noCMJ; countermovement jump: CMJ; drop jumps at 10, 20 and 30 cm drop height: DJ10, DJ20 and DJ30). Jumping height, pre-stretch augmentation and electromyographic activity of the plantar flexor muscles were measured.

Effect of Professional Denture Cleaning on Surface Roughness of Silicone or Acrylic Soft Relining Materials.

The aim of this study was to investigate the effects of combining mechanical (ultrasonic) and chemical cleaning (using denture cleaners) on the surface roughness of silicone or acrylic soft relining materials. The silicone soft relining material with the lowest Shore A hardness and a acrylic soft relining material routinely used in Japan were selected. Four groups were established based on type of treatment: immersion in water (W); ultrasonic cleaning in tap water (U); ultrasonic cleaning in a hypochlorous acid denture cleanser (HU); or ultrasonic cleaning in an acidic denture cleanser (AU).

Effects of acupuncture and acupressure of the acupoint compared to the tendon on the blood circulation of human tendon in vivo.

Purpose: The purpose of this study was to compare the effects of acupuncture and acupressure of acupoints on tendon blood circulation with those of both types of stimulation of tendon itself.

Methods: Before, during (except for acupressure), and after acupuncture and acupressure of the tendon and acupoint, blood circulation of the Achilles tendon was measured using red laser lights.

Results: The blood volume of the treated and non-treated tendons increased after acupuncture of the tendon (effect of time p = 0.

Determinants of joint stiffness and jumping height during drop jump.

The present study aimed to examine the effects of muscle-tendon mechanical properties and electromyographic activity on joint stiffness and jumping height and to explore the determinants of joint stiffness and jumping height. Twenty-nine males performed unilateral drop jumps at three drop heights (10, 20, and 30 cm) using only the ankle joint on the sledge apparatus. Ankle joint stiffness, jumping height, and electromyographic activity of the plantar flexor muscles were measured during drop jumps.

Effect of relaxation time on hysteresis of human tendon .

Objectives: The purpose of this study was to investigate the effect of relaxation time on tendon hysteresis.

Methods: Subjects exerted isometric plantar flexion torque from rest to maximal voluntary isometric contractions within around 0.5 s, followed by relaxation with six different times (0.

Maximal fascicle shortening velocity measurements in human medial gastrocnemius muscle in vivo.

This study evaluated the maximal fascicle shortening velocity under near-no-load conditions. In addition, we determined whether the rate of torque development during ballistic contraction was related to maximal fascicle shortening velocity. Under passive and active conditions, the medial gastrocnemius muscle fascicle shortening velocity was measured using ultrasonography at 300, 400, 500, 600, 700, 800, 900, and 1000 ° s .

Androgen receptor suppresses β-adrenoceptor-mediated CREB activation and thermogenesis in brown adipose tissue of male mice.

Thermoregulation is a process by which core body temperature is maintained in mammals. Males typically have a lower body temperature than females. However, the effects of androgens, which show higher levels in males, on adrenergic receptor-mediated thermogenesis remain unclear.

Rapid endothermal development of juvenile pacific bluefin tuna.

An important trait of Pacific bluefin tuna (PBT) is their ability to maintain their body temperature above the ambient temperature, which allows them to occupy a wider ecological niche. However, the size at which this ability in nature develops is unclear. Therefore, this study aimed to clarify this point by monitoring the body temperature and the surrounding ambient temperature as the fish grew.

Relationship between short latency stretch reflex and fascicle behavior in the soleus muscle .

Objectives: Stretch reflex responses were considered to be affected by the velocity of muscle fiber lengthening and angular velocity. However, the results of previous studies and are inconsistent in this regard. The purpose of the present study was to investigate the effects of the velocity of fascicle lengthening on the amplitude of the stretch reflex for each trial with a high angular velocity and wide range of motion.

Changes in tendon blood circulation and heart rate variability after intermittent compression to patellar and Achilles tendons.

Background: The purpose of this study was to compare changes in tendon blood circulation and heart rate variability after intermittent compression to the patellar and Achilles tendons.

Methods: Before the intermittent compression to tendons (3 min) and the recovery period (40 min), the blood volume and oxygen saturation of the patellar and Achilles tendons were measured using red laser lights. In addition, heart rate and ratio of low-frequency to high-frequency components of heart rate variability were measured.

Effect of short latency stretch reflex on passive and active muscle stiffness in the soleus muscle in vivo.

Purpose: The purpose of the present study was to determine the effect of the short latency stretch reflex on passive and active muscle stiffness in the soleus muscle.

Methods: Fourteen males participated in this study. Passive muscle stiffness was calculated from passive muscle force and fascicle length during passive lengthening at four different angular velocities (5, 50, 100, and 200 deg s).

Mechanical properties of muscles and tendon structures in middle-aged and young men.

The purpose of this study was to compare the mechanical properties of muscles and tendon structures for plantar flexor muscles at various strain rates and jump performances using single joint between middle-aged and young men in order to clarify the mechanisms of age-related decline in power output during vertical jump of middle-aged people previously reported. Passive muscle stiffness of the medial gastrocnemius muscle was determined based on passive muscle force and fascicle length during passive stretching at four angular velocities. Active muscle stiffness was calculated based on changes in muscle force and fascicle length during stretching at five angular velocities after submaximal isometric contractions.

Effects of plyometric training on muscle-tendon mechanical properties and behavior of fascicles during jumping.

The purpose of this study was to investigate the effects of plyometric training on the muscle-tendon mechanical properties and behavior of fascicles during jumping in order to elucidate the mechanisms of improved jump performance due to plyometric training. Eleven subjects completed a 12-week unilateral training program for plantar flexors. Active muscle stiffness with (100°·s ) and without (250°·s ) stretch reflex were calculated according to changes in muscle force and fascicle length during fast stretching after submaximal isometric contractions.

Mechanical properties of muscle and tendon at high strain rate in sprinters.

The aim of the present study was to compare the mechanical properties of muscles and tendons at high strain rates between sprinters and untrained men. Fifteen sprinters and 18 untrained men participated in this study. Active muscle stiffness of the medial gastrocnemius muscle was calculated according to changes in the estimated muscle force and fascicle length during fast stretching at five different angular velocities (100, 200, 300, 500, and 600 deg·s ) after submaximal isometric contractions.

Effect of angular velocity on active muscle stiffness in vivo.

We previously reported that active muscle stiffness could be evaluated in vivo. However, we were not able to investigate active muscle stiffness as more than 250 deg·s due to the limitation of the torque motor of dynamometer. The aim of the present study was to investigate the effect of angular velocities (including higher angular velocities of more than 250 deg·s) on active muscle stiffness.

Changes in Blood Circulation of the Tendons and Heart Rate Variability During and After Acupuncture.

The purpose of this study was to investigate the changes in blood circulation of tendons and heart rate variability (HRV) during and after acupuncture in order to elucidate the mechanisms of acupuncture-induced changes in tendon blood circulation. During 10 minutes of acupuncture treatment and a recovery period of 40 minutes, blood volume (THb) and oxygen saturation (StO) of treated and nontreated tendons were measured using red laser lights. In addition, HRV was also measured during the experimental period.

Effects of 4, 8, and 12 Repetition Maximum Resistance Training Protocols on Muscle Volume and Strength.

Kubo, K, Ikebukuro, T, and Yata, H. Effects of 4, 8, and 12 repetition maximum resistance training protocols on muscle volume and strength. J Strength Cond Res 35(4): 879-885, 2021-The purpose of this study was to determine skeletal muscle adaptations (strength and hypertrophy) in response to volume-equated resistance training with divergent repetition strategies.

Acupuncture- and Intermittent Compression-Induced Changes in Blood Circulation of Tendon.

The purpose of this study was to compare changes in blood circulation (blood volume and oxygen saturation [StO]) of tendon by acupuncture (insertion depth of the needle was 4 mm) and intermittent compression. Thirteen healthy volunteers (12 males and 1 female; age: 26.9 ± 9.

Comparison of adhesiveness of chewing gum to hard and soft denture base materials.

Purpose: The purpose of this study was to compare the adhesiveness of chewing gum to hard and soft denture base materials to investigate food retention associated with the basal surface of the denture.

Methods: Test specimens were fabricated using acrylic resin[Re], cobalt-chromium alloy[Co], zirconia[Zr], silicone soft relining material[SS], and acrylic soft relining material[AS]. Samples were set on a top-and-bottom pair lifting platform equipped with a digital force gauge.