Synergistic Dominance Induced by Hip Extension Exercise Alters Biomechanics and Muscular Activity During Sprinting and Suggests a Potential Link to Hamstring Strain.

Iguchi, J, Hojo, T, Fujisawa, Y, Kuzuhara, K, Yanase, K, Hirono, T, Koyama, Y, Tateuchi, H, and Ichihashi, N. Synergistic dominance induced by hip extension exercise alters biomechanics and muscular activity during sprinting and suggests a potential link to hamstring strain. J Strength Cond Res 37(9): 1770-1776, 2023-Hamstring strain is likely to occur during the late swing phase or the first half of the stance phase in sprinting.

Effects of shoulder position during static stretching on shear elastic modulus of biceps brachii muscle.

Biceps brachii muscle consists of a long head (BBL) and a short head (BBS). Shortening the BBL and BBS causes tendinopathy of the intertubercular groove and coracoid process. Therefore, it is necessary to stretch the BBL and BBS separately.

Acute changes in passive stiffness of the individual hamstring muscles induced by resistance exercise: effects of contraction mode and range of motion.

Purpose: Recent studies raise an interesting possibility that resistance exercise also decreases passive muscle stiffness, as does stretching exercise. However, little is known about how program variables of resistance exercise acutely influence muscle stiffness. We aimed to examine the acute changes in passive stiffness of the individual hamstring muscles after resistance exercises using different combinations of contraction modes and ranges of motion (ROMs).

Effective stretching position for the posterior deltoid muscle evaluated by shear wave elastography.

Background: Deteriorated extensibility of the posterior deltoid muscle is one of the factors of posterior shoulder tightness, and improvement in its extensibility is needed. However, no study has investigated which shoulder positions effectively stretch the posterior deltoid muscle in vivo. The aim of this study was to verify the effective stretching position of the posterior deltoid muscle in vivo by shear wave elastography.

Effective muscle elongation positions for the neck extensor muscles: An ultrasonic shear wave elastography study.

This study aimed to clarify the effective stretching positions for neck extensor muscles. Fifteen healthy men were measured shear moduli of the right neck extensor muscles using ultrasound shear wave elastography in following positions: rest (Rest), flexion (Flex), contralateral bending (Bend), flexion + contralateral bending (Flex → Bend), flexion + contralateral bending + contralateral rotation (Flex → Bend → ConRot), and flexion + contralateral bending + ipsilateral rotation (Flex → Bend → IpsRot). The increase in the shear modulus indicated a greater muscle elongation.

Epimuscular myofascial force transmission from biarticular rectus femoris elongation increases shear modulus of monoarticular quadriceps muscles.

This study aimed to examine the effect of rectus femoris (RF) elongation with passive hip angle change on the shear moduli of the vastus lateralis (VL) and medialis (VM) to verify whether Epimuscular myofascial force transmission (EMFT) occurs in the human quadriceps. Fourteen healthy men participated in this study. The shear moduli of the RF, VL, and VM were measured in four hip positions: flexion (Flex), extension and abduction (Ext-Abd), extension (Ext), and extension and adduction (Ext-Add).

Regional differential stretching of the pectoralis major muscle: An ultrasound elastography study.

Pectoralis major (PMa) muscle injuries are becoming more prevalent, and their incidence differs among the PMa regions, i.e., the clavicular, sternal, and abdominal regions.

Age-related changes in gait speeds and asymmetry during circular gait and straight-line gait in older individuals aged 60-79 years.

Aim: The present study aimed to investigate the age-related changes in gait speeds and asymmetry during circular and straight-line gaits among older adults aged 60-79 years.

Methods: The study included 391 community-dwelling older adults aged >60 years, who participated in the Nagahama cohort study. They were assigned to four age groups: 60-64 years (early 60s), 65-69 years (late 60s), 70-74 years (early 70s) and 75-79 years (late 70s).

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

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.

Differences in shear elastic modulus of the latissimus dorsi muscle during stretching among varied trunk positions.

The latissimus dorsi (LD) can be divided into the upper, middle, and lower parts, but the effective stretching positions for each part are unknown. In this study, we aimed to investigate effective trunk positions for stretching of the LD. A total of 14 healthy males participated in this study.

Association of Pain History and Current Pain With Sagittal Spinal Alignment and Muscle Stiffness and Muscle Mass of the Back Muscles in Middle-aged and Elderly Women.

Study Design: A cross-sectional study.

Objective: To investigate the association of low back pain history (LBPH) and LBP with sagittal spinal alignment, stiffness assessed using ultrasonic shear wave elastography, and mass of the back muscle in community-dwelling middle-aged and elderly women.

Summary Of Background Data: The association of LBPH and LBP with sagittal spinal alignment, stiffness, and mass of the back muscles remains unclear in middle-aged and elderly women.

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles, and sagittal spinal alignment in young and middle-aged medical workers.

Background: Muscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.

Methods: The study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group).

Ankle and toe muscle strength characteristics in runners with a history of medial tibial stress syndrome.

Background: A high proportion of flexor digitorum longus attachment is found at the posteromedial border of the tibia, which is the most common location of medial tibial stress syndrome (MTSS). Therefore, plantar flexion strength of the lesser toes could be related to MTSS; however, the relationship between MTSS and muscle strength of the hallux and lesser toes is not yet evaluated due to the lack of quantitative methods. This study investigated the muscle strength characteristics in runners with a history of MTSS by using a newly developed device to measure the muscle strength of the hallux, lesser toes, and ankle.

Improvement in muscle strength with low-load isotonic training depends on fascicle length but not joint angle.

Introduction: In this study we investigate whether low-load isotonic training will elicit greater improvement in muscle strength at the same fascicle length, rather than at the same joint angle.

Methods: Sixteen healthy men (24.1 ± 2.

Shoulder horizontal abduction stretching effectively increases shear elastic modulus of pectoralis minor muscle.

Background: Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography.

Effects of two stretching methods on shoulder range of motion and muscle stiffness in baseball players with posterior shoulder tightness: a randomized controlled trial.

Background: The cross-body stretch and sleeper stretch are widely used for improving flexibility of the posterior shoulder. These stretching methods were modified by Wilk. However, few quantitative data are available on the new, modified stretching methods.