Electrical Stimulation to the Infraspinatus on Hypertrophy and Strength of the Shoulder.

The purpose of this study was to determine the effects of six weeks of electrical muscle stimulation (EMS) on the strength and muscle mass of the infraspinatus muscle. Twenty non-athletes (age: 24±3.4 years, height: 171.5±5.6 cm, mass: 65.2±8.1 kg) were randomly classified into two groups, an electrical muscle stimulation group (EMS group) and a control group (CON group). The EMS group completed a total of 18 20- min EMS sessions, three times per week over a period of six weeks, while the CON group received no intervention. The muscle thicknesses of both the infraspinatus and the deltoid muscles, the cross-sectional area (CSA) of the whole infraspinatus muscle, and the isometric and isokinetic peak torques of shoulder external rotations were measured before and after intervention. It was found that the muscle thickness of the superior infraspinatus (Pre 0.92±0.19 cm2, Post 0.99±0.16 cm2, p=0.02) and the CSA (Pre 10.99±1.32 cm2, Post 11.99±1.02 cm2, p=0.03) significantly increased in the EMS group. This study demonstrated that EMS of the infraspinatus muscle over a period of six weeks resulted in hypertrophy of the infraspinatus muscle.

Association of Activities of Daily Living With Load During Step Ascent Motion in Nursing Home-Residing Elderly Individuals: An Observational Study.

OBJECTIVE: This study aimed to examine the association of independence in activities of daily living with the loads during step ascent motion and other motor functions in 32 nursing home-residing elderly individuals. DESIGN: Independence in activities of daily living was assessed by using the Functional Independence Measure. The loads at the upper (i.e., pulling up) and lower (i.e., pushing up) levels during the step ascent task was measured on a step ascent platform. Hip extensor, knee extensor, plantar flexor muscle, and quadriceps setting strengths; lower extremity agility using the stepping test; and hip and knee joint pain severities were measured. One-legged stance and functional reach distance for balance and maximal walking speed, timed up-and-go time, five-chair-stand time, and step ascent time were also measured to assess mobility. RESULTS: Stepwise regression analysis revealed that the load at pushing up during step ascent motion and timed up-and-go time were significant and independent determinants of Functional Independence Measure score. Functional Independence Measure score decreased with decreased load at pushing up and increased timed up-and-go time. CONCLUSIONS: The study results suggest that depending on task specificity, both one step up task's push-up peak load during step ascent motion and timed up-and-go can partially explain activities of daily living's Functional Independence Measure score in nursing home-residing elderly individuals. Lower extremity muscle strength, agility, pain, or balance measures did not add to the prediction.

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 ± 2.5 years of age) were randomly divided into intervention and control groups. Pre- and posttraining maximum isometric and isokinetic strengths and fascicle lengths of the medial gastrocnemius muscle were measured. Isotonic resistance training at 15 ° to 30 ° ankle plantarflexion at low intensity was conducted for 4 weeks. RESULTS: The maximum isometric and isokinetic strength of the intervention group increased significantly only at 15 ° dorsiflexion and 8 ° to 12 ° dorsiflexion. Fascicle length during maximum voluntary contraction at 15 ° dorsiflexion to 0 ° was similar to fascicle length under training conditions. DISCUSSION: It is possible that the improvement in muscle strength with low-load training depends on fascicle length rather than joint angle. Muscle Nerve 57: 83-89, 2018.

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. METHODS: Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver-angle combinations. RESULTS: The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°. CONCLUSIONS: This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo.

Association between physical function and the load pattern during stepping-up motion in community-dwelling elderly women.

OBJECTIVE: Stepping-up motion is challenging task for elderly people in daily life. The present study investigated the relationship between the load pattern during stepping-up motion at maximum speed and physical function in elderly women. METHODS: The subjects comprised 109 community-dwelling elderly women (age 72.5±5.3years). The load pattern (maximum load, rate of load production, and stepping-up time) during ascending a 30cm step at maximum speed was measured, using a step up platform that measures the load at the lower and upper level. Physical function, including hip and knee extensor strength and performance on the vertical jump test, one-legged stance test, timed "Up & Go" (TUG) test, and stepping test were measured. RESULTS: Pearson's correlation analysis showed that stepping-up time was correlated with the maximum load at the lower level (r=-0.51), but not with the maximum load at the upper level. A multiple regression analysis showed that hip extensor strength and performance on the vertical jump, TUG, and stepping tests were significant determinants of the load pattern during stepping-up motion in the elderly women. CONCLUSIONS: Our study revealed that rapid stepping-up ability was more closely related to the maximum load during push-off at the lower level rather than that during weight loading on the upper level, and that the load pattern during stepping-up motion in elderly women was associated with various physical functions such as the hip extensor strength, leg muscle power, dynamic balance function, and agility.

Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.