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weight lifting and muscle

Deema Totah, Lauro Ojeda, Daniel D Johnson, Deanna Gates, Emily Mower Provost, Kira Barton
OBJECTIVE: Numerous devices have been designed to support the back during lifting tasks. To improve the utility of such devices, this research explores the use of preparatory muscle activity to classify muscle loading and initiate appropriate device activation. The goal of this study was to determine the earliest time window that enabled accurate load classification during a dynamic lifting task. METHODS: Nine subjects performed thirty symmetrical lifts, split evenly across three weight conditions (no-weight, 10-lbs and 24-lbs), while low-back muscle activity data was collected...
2018: PloS One
Yanhui Song, Susheng Zhou, Kaiyun Jin, Jian Qiao, Da Li, Chao Xu, Dongmei Hu, Jiangtao Di, Min Li, Zuoguang Zhang, Qingwen Li
Hybrid smart actuators fabricated using composites of carbon fibers and shape memory polymers have been extensively studied in recent years. However, relatively slow shape recovery has combined with the reset of shape deformation during cycles to restrict their practical use. An electrothermally reversible actuator based on carbon nanotube (CNT) composite yarn containing CNT fiber and thermoplastic polyurethane (TPU) resin with excellent shape memory was investigated in this paper. The combination of CNT yarn and TPU resin considerably amplified the contraction and stability...
February 12, 2018: Nanoscale
Alberto de Castro Pochini, Marcus de Souza Barbosa Rodrigues, Larissa Yamashita, Paulo Santoro Belangero, Carlos Vicente Andreoli, Benno Ejnisman
Objective: To assess the tendon reconstruction technique for total rupture of the pectoralis major muscle using an adjustable cortical button. Methods: Prospective study of 27 male patients with a mean age of 29.9 (SD = 5.3 years) and follow-up of 2.3 years. The procedure consisted of autologous grafts taken from the semitendinosus and gracilis tendons and an adjustable cortical button. Patients were evaluated functionally by the Bak criteria. Results: The surgical treatment of pectoralis major muscle tendon reconstruction was performed in the early stages (three weeks) in six patients (22...
January 2018: Revista Brasileira de Ortopedia
Kevin P Liles, Angelique F Greene, Mary K Danielson, Nathan D Colley, Andrew Wellen, Jeremy M Fisher, Jonathan C Barnes
The use of light to actuate materials is advantageous because it represents a cost-effective and operationally straightforward way to introduce energy into a stimuli-responsive system. Common strategies for photoinduced actuation of materials typically rely on light irradiation to isomerize azobenzene or spiropyran derivatives, or to induce unidirectional rotation of molecular motors incorporated into a 3D polymer network. Although interest in photoredox catalysis has risen exponentially in the past decade, there are far fewer examples where photoinduced electron transfer (PET) processes are employed to actuate materials...
January 24, 2018: Macromolecular Rapid Communications
Jiawen Chen, Franco King-Chi Leung, Marc C A Stuart, Takashi Kajitani, Takanori Fukushima, Erik van der Giessen, Ben L Feringa
A striking feature of living systems is their ability to produce motility by amplification of collective molecular motion from the nanoscale up to macroscopic dimensions. Some of nature's protein motors, such as myosin in muscle tissue, consist of a hierarchical supramolecular assembly of very large proteins, in which mechanical stress induces a coordinated movement. However, artificial molecular muscles have often relied on covalent polymer-based actuators. Here, we describe the macroscopic contractile muscle-like motion of a supramolecular system (comprising 95% water) formed by the hierarchical self-assembly of a photoresponsive amphiphilic molecular motor...
February 2018: Nature Chemistry
Sharon M H Tsang, Billy C L So, Rufina W L Lau, Jie Dai, Grace P Y Szeto
PURPOSE: This study compared the effects of "Ergomotor" intervention and conventional physiotherapy, on influencing the motor control in the neck-shoulder region in people with work-related neck-shoulder pain (WRNSP). METHODS: 101 patients (age range 20-54 years) diagnosed with chronic WRNSP were randomized into control (CO) group (n = 50) and Ergomotor (EM) group (n = 51). Each group received a 12-week intervention. Participants in CO group received treatment for pain relief and general exercises...
April 2018: European Journal of Applied Physiology
Arda Kotikian, Ryan L Truby, John William Boley, Timothy J White, Jennifer A Lewis
Liquid crystal elastomers (LCEs) are soft materials capable of large, reversible shape changes, which may find potential application as artificial muscles, soft robots, and dynamic functional architectures. Here, the design and additive manufacturing of LCE actuators (LCEAs) with spatially programed nematic order that exhibit large, reversible, and repeatable contraction with high specific work capacity are reported. First, a photopolymerizable, solvent-free, main-chain LCE ink is created via aza-Michael addition with the appropriate viscoelastic properties for 3D printing...
January 15, 2018: Advanced Materials
Anat Ratnovsky, Emanuel Kusayev, Sara Naftali
A flexible piezoelectric thin film sensor has been proposed recently in several studies for detection of muscle movements. The objective of this study was to investigate the ability of this sensor to assess skeletal muscle performance and fatigue under isokinetic contractions. Simultaneous noninvasive measurements of muscles activity were done using surface electromyography (EMG) electrodes and two thin film piezoelectric sensors. Measurements were taken from the biceps during slow and fast elbow flexion with and without strong grip, during different weight lifting and from the gastrocnemius during treadmill marching at speeds of 4 and of 10 kph...
January 5, 2018: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
Hoe-Song Yang
BACKGROUND: Patients suffering from low back pain (LBP) have been reported to alter muscle contraction strategies. OBJECTIVE: To compare activity and thickness of the trunk muscles (external oblique (EO), internal oblique (IO), transversus abdominis (TrA), and lumbar multifidus (LM)) during static stoop lift at different lifting loads between the subjects with and without LBP. METHODS: Twenty eight subjects with LBP and twenty healthy subjects were recruited...
December 29, 2017: Journal of Back and Musculoskeletal Rehabilitation
Fahed Mehyar, Marcio Santos, Sara E Wilson, Vincent S Staggs, Neena K Sharma
Objective: The purpose of this study was to investigate the effect of grade IV lumbar mobilization on the activity/contraction of erector spinae (ES) and lumbar multifidus (LM) muscles in healthy people. Methods: A randomized, repeated-measures design was used. Sixteen healthy subjects attended 3 testing sessions with a different intervention in each session (no intervention, grade IV central lumbar mobilization at L4, and placebo/light touch). Lying in a prone position, subjects lifted a light weight with their right arm while ultrasound images of LM and surface electromyography signals of ES were captured before and immediately after application of the intervention in the session...
December 2017: Journal of Chiropractic Medicine
Alycia S Gailey, Sasha Blue Godfrey, Ryan E Breighner, Karen L Andrews, Kristin D Zhao, Antonio Bicchi, Marco Santello
Current prosthetic hands are frequently rejected in part due to limited functionality and versatility. We assessed the feasibility of a novel prosthetic hand, the SoftHand Pro (SHP), whose design combines soft robotics and hand postural synergies. Able-bodied subjects ( ) tracked cursor motion by opening and closing the SHP and performed a grasp-lift-hold-release (GLHR) task with a sensorized cylindrical object of variable weight. The SHP control was driven by electromyographic (EMG) signals from two antagonistic muscles...
December 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Tarek M El-Gohary, Samiha M Abd Elkader, Hatem A Emara, Mahmoud I Ibrahim, Osama A Khaled, Mostafa S Ahmed
BACKGROUND: Spinal muscles endurance is fundamental for providing adequate trunk stability. OBJECTIVE: The purpose of this study was to compare the side bridge static endurance ability of the right versus left side. METHODS: Forty right hand dominant students, aged between 18 and 25 years, were recruited from Taibah University. Every participant had to lie down on his side and bear trunk weight on the arm with shoulder abducted to 90∘ and elbow flexed to 90∘...
November 17, 2017: Journal of Back and Musculoskeletal Rehabilitation
Guochuang Xu, Miao Zhang, Qinqin Zhou, Hongwu Chen, Tiantian Gao, Chun Li, Gaoquan Shi
A high-performance actuator should be able to deliver large-shape deformations, fast actuations and sensitive responses to multiple stimuli. Here, we report such an actuator constructed from one layer of polyvinylidene fluoride (PVDF) with a high coefficient of thermal expansion (CTE), and another layer of small sheets of graphene oxide (SGO) with a negative CTE. The opposite deformations of both actuation layers make the SGO/PVDF bilayer actuator highly sensitive to the temperature stimulus with a large bending sensitivity of 1...
November 16, 2017: Nanoscale
Z El Ouaaid, A Shirazi-Adl, A Plamondon
To reduce lifting and associated low back injuries, manual material handling operations often involve pulling-pushing of carts at different weights, orientations, and heights. The loads on spine and risk of injury however need to be investigated. The aim of this study was to evaluate muscle forces, spinal loads and trunk stability in pull-push tasks in sagittal-symmetric, static upright standing posture. Three hand-held load magnitudes (80, 120 and 160 N) at four elevations (0, 20, 40 and 60 cm to the L5-S1) and 24 force directions covering all pull/push orientations were considered...
October 25, 2017: Journal of Biomechanics
Kevin McCurdy, John Walker, Derrick Yuen
McCurdy, K, Walker, J, and Yuen, D. Gluteus maximus and hamstring activation during selected weight-bearing resistance exercises. J Strength Cond Res XX(X): 000-000, 2017-The purpose of this study was to compare the gluteus maximus (GM) and hamstring group (HG) electromyographic (EMG) activation levels among selected weight-bearing resistance exercises. Eighteen young adult females with previous resistance training experience completed the study. Strength was assessed on the bilateral squat (BS) (3 repetition maximum [RM]), modified single-leg squat (MSLS) (3RM), and stiff-leg deadlift (SLDL) (8RM) to determine an 8RM load for all lifts...
October 20, 2017: Journal of Strength and Conditioning Research
Safvet Ors
INTRODUCTION: Several factors, such as aging, pregnancy, and weight loss, reduce the elasticity of the breast tissue, and ptosis occurs. Due to aging and gravity, it is not possible to completely prevent breast ptosis. The goal is to delay the recurrence of ptosis as much as possible. PATIENTS AND METHODS: This study included 20 female patients aged 25-55 years. The patients who underwent surgery had different levels of ptosis. Although the patients wanted their breasts to be lifted and an increase in projection, they did not want implants to be used...
October 26, 2017: Aesthetic Plastic Surgery
Ronald L Moy, Lauren Moy
BACKGROUND: Patients who are aging, with weight gain, and increased skin laxity, request dermatologists to improve their neck area. Surgical and nonsurgical options are reviewed as well as benefits and side effects. This article will focus on how surgical techniques can be applied for male patients in particular. OBJECTIVE: To review surgical neck rejuvenation therapies available currently to find the best option for male patients. CONCLUSION: Surgical treatment of the male neck to improve mandibular contour and loose neck skin requires tightening of the platysmal muscle and usually skin removal in the postauricular sulcus and into the hairline...
November 2017: Dermatologic Surgery: Official Publication for American Society for Dermatologic Surgery [et Al.]
Ranjit K Mal
No abstract text is available yet for this article.
October 23, 2017: Scandinavian Journal of Medicine & Science in Sports
Melanie D Bussey, Marcelo Peduzzi de Castro, Daniela Aldabe, Jonathan Shemmell
The aim of this study was to assess the influence of sex on the kinetic, kinematic and neuromuscular correlates of anticipatory postural adjustments (APAs) during a single leg lift task performed by healthy participants. Fifty healthy age and body mass index matched participants (25 women and 25 men) performed 20 single leg lift task (hip flexion to 90 ° as quickly as possible) with their dominant and their non-dominant lower limbs. A force plate was used to determine the medial-lateral displacement of the center of pressure (COPML), and the initiation of weight shift (T0); kinematics was used to determine leg lift (T1); and electromyography was used to determine onset times from eight muscles: bilateral external oblique, internal oblique and lumbar multifidus, and unilateral (stance limb) gluteus maximus and biceps femoris...
October 17, 2017: Human Movement Science
Saman Madinei, Xiaopeng Ning
The performance of manual material handling tasks is one major cause of lower back injuries. In the current study, we investigated the influence of the weight configuration of hand loads on trunk muscle activities and the associated spinal stability. Thirteen volunteers each performed static weight holding tasks using two different 9 kg weight bars (with medial and lateral weight configurations) at two levels of heights (low and high) and one fixed horizontal distance (which resulted in constant spinal joint moment across conditions)...
October 2, 2017: Ergonomics
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