scholarly journals Development and Experimental Verification of an Ergonomic Backpack

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mohamed Z. Ramadan ◽  
Sultan N. Al-Tayyar
Keyword(s):  
Body Weight ◽  
Experimental Verification ◽  
Continuous Monitoring ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
The Body ◽  
Oblique Muscle ◽  
Independent Variables ◽  
Reducing Activity ◽  
Spinal Muscles

Carrying a heavy school backpack has extensively been reported as a prime cause of children’s body strain. It is suggested that the load should not exceed 10 percent of the child’s body weight; however, ensuring this requires continuous monitoring. The study explores how ergonomically designed school backpack based on the user anthropometric data (n=280) and ergonomic parameters help reduce force concentration on shoulders and back. It provides a validation process of the developed prototype by experimental verification. The developed design was assessed in a comparison experiment with a commercially available local school backpack. An experimental study was used which recruited thirty healthy college students (aged 19 to 23 years). Two independent variables evaluated were school backpack type (developed backpack versus commercial one) and load levels as a percentage of body weight. Three load levels were employed 10%, 15%, and 20%. These variables were measured on the responses: bag comfort scale and the percent of maximum voluntary contraction (%MVC) of six muscles (right and left of erector spine, right and left of external abdominal oblique muscle, and right and left of trapezius). The developed backpack provided astonishing performance at levels of 15% and 20% of body weight in terms of subjective measure and electromyography (EMG) responses. It also showed that increasing the carried weight more than 10% result in reducing activity on the erector spinal muscles, while it increases on abdominal oblique muscles. The developed backpack design confirmed the efficiency of its bases by distributing the carried weight among the trunk through side pockets, attached to the body through two upper and lower straps. It helped the body to distribute the carried weight and avoid concentrating pressure on specific areas.

scholarly journals Pre-Exercise Rehydration Attenuates Central Fatigability during 2-Min Maximum Voluntary Contraction in Hyperthermia

Medicina ◽  
2019 ◽  
Vol 55 (3) ◽  
pp. 66
Author(s):  
Kazys Vadopalas ◽  
Aivaras Ratkevičius ◽  
Albertas Skurvydas ◽  
Saulė Sipavičienė ◽  
Marius Brazaitis
Keyword(s):  
Body Weight ◽  
Physiological Stress ◽  
Maximum Voluntary Contraction ◽  
Thermal Strain ◽  
Plasma Osmolality ◽  
Voluntary Contraction ◽  
Whole Body ◽  
Knee Extensors ◽  
Lower Body ◽  
Whole Body Hyperthermia

Background and objectives: Hyperthermia with dehydration alters several brain structure volumes, mainly by changing plasma osmolality, thus strongly affecting neural functions (cognitive and motor). Here, we aimed to examine whether the prevention of significant dehydration caused by passively induced whole-body hyperthermia attenuates peripheral and/or central fatigability during a sustained 2-min isometric maximal voluntary contraction (MVC). Materials and Methods: Ten healthy and physically active adult men (21 ± 1 years of age) performed an isometric MVC of the knee extensors for 2 min (2-min MVC) under control (CON) conditions, after passive lower-body heating that induced severe whole-body hyperthermia (HT, Tre > 39 °C) with dehydration (HT-D) and after HT with rehydration (HT-RH). Results: In the HT-D trial, the subjects lost 0.94 ± 0.15 kg (1.33% ± 0.13%) of their body weight; in the HT-RH trial, their body weight increased by 0.1 ± 0.42 kg (0.1% ± 0.58%). After lower-body heating, the HT-RH trial (vs. HT-D trial) was accompanied by a significantly lower physiological stress index (6.77 ± 0.98 vs. 7.40 ± 1.46, respectively), heart rate (47.8 ± 9.8 vs. 60.8 ± 13.2 b min−1, respectively), and systolic blood pressure (−12.52 ± 5.1 vs. +2.3 ± 6.4, respectively). During 2-min MVC, hyperthermia (HT-D; HT-RH) resulted in greater central fatigability compared with the CON trial. The voluntary activation of exercising muscles was less depressed in the HT-RH trial compared with the HT-D trial. Over the exercise period, electrically (involuntary) induced torque decreased less in the HT-D trial than in the CON and HT-RH trials. Conclusions: Our results suggest that pre-exercise rehydration might have the immediate positive effect of reducing physiological thermal strain, thus attenuating central fatigability even when exercise is performed during severe (Tre > 39 °C) HT, induced by passive warming of the lower body.

Application of multiple regression analysis to morphometric characters obtained from Serranus cabrilla (linnaeus, 1758) by using stepwise method

2017 ◽  
Author(s):  
Levent Sangün ◽  
O. Ýnanç Güney
Keyword(s):  
Body Weight ◽  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
The Body ◽  
Stepwise Multiple Regression ◽  
Morphometric Characters ◽  
Independent Variables ◽  
Fisheries Science ◽  
Stepwise Method

In fisheries science, high number of morphometric measures (independent variables) taken from different parts of the fish complicates the estimation of the body weight (dependent variable). Therefore, the researchers are seeking for a solution facilitating the interpretation of the equations of correlation between the characteristics. One way to deal with this challenge is the dimension reduction by means of stepwise multiple regression analysis. The aim of this study is to explain total variation with the same accuracy by using fewer independent variables. To accomplish this, 12 morphometric measures from 210 individuals of Serranus cabrilla were measured to estimate the body weight. Firstly, the 95% of the variation was explained by means of multiple regression analysis by using all variables. Then, by step-wise method, the same results were achieved with fewer independent variables. Finally, the variables with inter-multicollinearity eliminated and with two remaining independent variables determination coefficients resulted as 95%. The result showed that using more variables does not create significant distinction for accuracy to estimate the body weight although; the total length and body dept was the most effective features for weight.

scholarly journals Assessment of Muscular Activity and Postural Load During Coffee Harvesting Activities – A Case Study

2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Sebastián Alberto Pelaez ◽  
Leonardo Augusto Quintana
Keyword(s):  
Maximum Voluntary Contraction ◽  
Muscular Activity ◽  
Voluntary Contraction ◽  
The Body ◽  
Repetitive Movement ◽  
Dynamic Activity ◽  
Activity Assessment ◽  
Lower Back ◽  
Postural Load

Objective: The goal of this case study was to analyze and evaluate the posture, force and repetitive movement risks associated with manual coffee harvesting activities. Materials and Methods: A self-discomfort report was administered to 28 participants, of whom 4 volunteered for an evaluation of postural load on muscular activity using electromyography and electrogoniometry. Eight upper limb muscles and the kinematics of the wrist and upper arm of the dominant arm were assessed. Results: The results of the self-discomfort report showed a greater demand, from the harvester’s perception, in areas such as the back, lower back, knees and feet during a period of one week of work. The outcomes of the muscular activity assessment showed that the extensor carpi ulnaris (ECR) was the muscle with the highest demand during the assessment. The dynamic activity of the muscle exceeded 20% of the maximum voluntary contraction (MVC), which classifies coffee harvesting as a threatening activity. The postural load on the body segments revealed that wrist deviation was critical due to an abnormal range of the wrists during the activity. Conclusions: It is necessary to improve the working conditions of the coffee harvesters.

scholarly journals Effect of kinesio taping in myoelectric activity in patients with shoulder impingement

2020 ◽  
pp. 1-7
Author(s):  
William Dhein ◽  
Marcelo La Torre ◽  
And Jefferson Fagundes Loss
Keyword(s):  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
The Body ◽  
Wilcoxon Test ◽  
Shoulder Abduction ◽  
Myoelectric Activity ◽  
Kinesio Taping ◽  
Upper Trapezius ◽  
Occupational Activities ◽  
Impact Syndrome

Introduction: The complex shoulder joint is equipped with the greater joint mobility of the body, however, is commonly injured in repetitive, sport or occupational activities. Shoulder Impact Syndrome (SIS) is one of the most common injuries affecting the shoulder, thus causing limitations in its functionality. Several strategies have been used by physiotherapy for prevention and rehabilitation of SIS, one of them is the Kinesio Taping (KT). However, even with its abundant use there is still no clear evidence of its benefits. Objective: The aim of the study was to examine the effect of KT on myoelectric activity and the level of pain in patients with SIS. Method: Seven women with SIS participated, which performed the flexion and shoulder abduction up to 90° with and without KT. During the gestures, the pain level and surface electromyography data of the upper trapezoid, middle deltoid and anterior serratus were acquired. The treatment of the electromyography data was performed in the BIOMEC-SAS software and presented as percentage values of the maximum voluntary contraction. To compare the myoelectric activity and pain levels, it was performed, respectively, one way ANOVA and the Wilcoxon test (α <0.05). Results: Pain reductions were observed and myoelectric activity of upper trapezius (46.0±34.4% MVIC to 35.6 ± 19.5% MVIC) and middle deltoid (39.0±11.5% MVIC to 35.2±12.5% MVIC) in motion abduction use of KT. No changes were observed in the signs during flexion movement. Conclusion: Finally, the KT generated a reduction in the level of pain and myoelectric activity of the middle deltoid and upper trapezius in the movement of abduction in patients with SIS.

scholarly journals Acute Effect of Sodium Bicarbonate Supplementation on Symptoms of Gastrointestinal Discomfort, Acid‐Base Balance, and Performance of Jiu‐Jitsu Athletes

2020 ◽  
Vol 75 (1) ◽  
pp. 85-93
Author(s):  
Luciano Ragone ◽  
João Guilherme Vieira ◽  
Mateus Camaroti Laterza ◽  
Luis Leitão ◽  
Jefferson da Silva Novaes ◽  
...  
Keyword(s):  
Body Weight ◽  
Sodium Bicarbonate ◽  
Isometric Contraction ◽  
Maximum Voluntary Contraction ◽  
Acute Effect ◽  
Voluntary Contraction ◽  
Acid Base Balance ◽  
Acid Base ◽  
Gastrointestinal Discomfort ◽  
Base Balance

Abstract The purpose of the present study was to verify the acute effect of sodium bicarbonate supplementation on symptoms of gastrointestinal discomfort, acid-base balance and intermittent isometric handgrip test performance in Jiu-Jitsu athletes. Ten male (22.2 ± 3.9 years; 174 ± 0.07 cm; 74.5 ± 8.9 kg) jiu-jitsu athletes participated in this counterbalanced double-blind crossover study. Two protocols, a) supplementation with 0.3 g.kg-1 of body weight of sodium bicarbonate, and b) supplementation with 0.045 g.kg-1 of body weight of placebo substance, were employed. Gastrointestinal tolerability was assessed by the questionnaire. Blood samples were collected at three time points (baseline, pre-ISO, and post-ISO) to determine the responses of potential hydrogenionic (pH), bicarbonate (HCO3- ), base excess (EB) and lactate concentrations. The maximum voluntary contraction test and the intermittent isometric contraction test were also performed. As a result, none of the athletes reported significant gastrointestinal discomfort (p > 0.05). HCO3- , pH, and EB at the pre-ISO and post-ISO moments were significantly higher for the sodium bicarbonate protocol. Lactate concentrations were significantly higher for both post-ISO protocols (p = 0.000). There was no significant difference in the performance of the maximum voluntary contraction test and the intermittent isometric contraction test (p > 0.05). Thus, we conclude that sodium bicarbonate supplementation does not generate adverse responses resulting in gastrointestinal discomfort, and does not benefit performance yet promotes a state of metabolic alkalosis.

Whole-Body Reaching Movements Formulated by Minimum Muscle-Tension Change Criterion

2016 ◽  
Vol 28 (5) ◽  
pp. 950-969 ◽  
Author(s):  
Naoki Kudo ◽  
Kyuheong Choi ◽  
Takahiro Kagawa ◽  
Yoji Uno
Keyword(s):  
Muscle Tension ◽  
Maximum Voluntary Contraction ◽  
Weighting Factor ◽  
Voluntary Contraction ◽  
The Body ◽  
Joint Torque ◽  
Reaching Movements ◽  
Whole Body ◽  
Hand Position ◽  
Tension Change

It is well known that planar reaching movements of the human shoulder and elbow joints have invariant features: roughly straight hand paths and bell-shaped velocity profiles. The optimal control models with the criteria of smoothness or precision, which determine a unique movement pattern, predict such features of hand trajectories. In this letter on expanding the research on simple arm reaching movements, we examine whether the smoothness criteria can be applied to whole-body reaching movements with many degrees of freedom. Determining a suitable joint trajectory in the whole-body reaching movement corresponds to the optimization problem with constraints, since body balance must be maintained during a motion task. First, we measured human joint trajectories and ground reaction forces during whole-body reaching movements, and confirmed that subjects formed similar movements with common characteristics in the trajectories of the hand position and body center of mass. Second, we calculated the optimal trajectories according to the criteria of torque and muscle-tension smoothness. While the minimum torque change trajectories were not consistent with the experimental data, the minimum muscle-tension change model was able to predict the stereotyped features of the measured trajectories. To explore the dominant effects of the extension from the torque change to the muscle-tension change, we introduced a weighted torque change cost function. Considering the maximum voluntary contraction (MVC) force of the muscle as the weighting factor of each joint torque, we formulated the weighted torque change cost as a simplified version of the minimum muscle-tension change cost. The trajectories owing to the minimum weighted torque change criterion also showed qualitative agreement with the common features of the measured data. Proper estimation of the MVC forces in the body joints is essential to reproduce human whole-body movements according to the minimum muscle-tension change criterion.

scholarly journals Environmental temperature and exercise modality independently impact central and muscle fatigue among people with multiple sclerosis

2017 ◽  
Vol 3 (4) ◽  
pp. 205521731774762 ◽  
Author(s):  
Geetika Grover ◽  
Michelle Ploughman ◽  
Devin T Philpott ◽  
Liam P Kelly ◽  
Augustine J Devasahayam ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Body Weight ◽  
Body Temperature ◽  
Aerobic Exercise ◽  
Muscle Fatigue ◽  
Room Temperature ◽  
Environmental Temperature ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Total Body

Background Heat sensitivity and fatigue limit the ability of multiple sclerosis patients to participate in exercise. Objective The purpose of this study was to determine the optimal aerobic exercise parameters (environmental temperature and exercise modality) to limit exercise-induced central and muscle fatigue among people with multiple sclerosis. Methods Fourteen people with multiple sclerosis with varying levels of disability completed four randomized exercise sessions at 65% of the maximal volume of oxygen: body-weight supported treadmill cool (16°C), body-weight supported treadmill room (21°C), total-body recumbent stepper cool and total-body recumbent stepper room. Maximum voluntary contraction, electromyography, and evoked contractile properties were collected from the more affected plantar flexors along with subjective levels of fatigue, body temperature and perceived level of exertion. Results Exercise in cooler room temperature increased maximum voluntary contraction force ( p = 0.010) and stabilized body temperature ( p = 0.011) compared to standard room temperature. People with multiple sclerosis experienced greater peak twitch torque ( p = 0.047), shorter time to peak twitch ( p = 0.035) and a longer half relaxation time ( p = 0.046) after total-body recumbent stepper suggestive of less muscle fatigue. Conclusion Cooling the exercise environment limits the negative effects of central fatigue during aerobic exercise and using total-body recumbent stepper (work distributed among four limbs) rather than body-weight supported treadmill lessens muscular fatigue. Therapists can titrate these two variables to help people with multiple sclerosis achieve sufficient exercise workloads.

scholarly journals Parylene-Based Flexible Microelectrode Arrays for the Electrical Recording of Muscles and the Effect of Electrode Size

2020 ◽  
Vol 10 (20) ◽  
pp. 7364
Author(s):  
Bong-Jun Choi ◽  
Ju-Hwan Kim ◽  
Woo-Jin Yang ◽  
Dong-Jun Han ◽  
Jaewon Park ◽  
...  
Keyword(s):  
Small Area ◽  
Microelectrode Array ◽  
Maximum Voluntary Contraction ◽  
Microelectrode Arrays ◽  
Specific Area ◽  
Skin Surface ◽  
Voluntary Contraction ◽  
The Body ◽  
Electrode Size ◽  
Semg Signals

Miniaturized flexible microelectrode arrays are desirable for small-area surface electromyography (sEMG) to detect the electrical activity generated by muscles in a specific area of the body. Here, we present a flexible 8-channel microelectrode array with electrodes of diameter 150–300 μm for small-area sEMG recordings. The microelectrode arrays based on a flexible Parylene C substrate recorded the sEMG signals from a curved skin surface with a maximum signal-to-noise ratio (SNR) of 21.4 dB. The sEMG signals recorded from a small area of 17671–59325 μm2 showed a clear distinction between the signal and noise. Further, the sEMG data were analyzed in the frequency domain by converting the signals via fast Fourier transform (FFT), and it was verified that the proposed microelectrode could reliably record multichannel sEMGs over a small area. Moreover, a maximum voluntary contraction (MVC) experiment was performed to confirm the recording capability of the microelectrode array, which showed consistency with the previous reports. Finally, we demonstrated the effects of the electrode size by comparing the results for two different electrode sizes. When the electrode size was increased 3.37 times, the root-mean-square value of the amplitude (Vrms) increased 2.64 times, consequently increasing the SNR from 16.9 to 21.4 dB. This study demonstrates the expanded utility of Parylene-based flexible microelectrode arrays.

L-Ascorbic Acid Addition to Chitosan Reduces Body Weight in Overweight Women

2014 ◽  
Vol 84 (1-2) ◽  
pp. 5-11 ◽  
Author(s):  
Eun Y. Jung ◽  
Sung C. Jun ◽  
Un J. Chang ◽  
Hyung J. Suh
Keyword(s):  
Ascorbic Acid ◽  
Body Weight ◽  
Fat Body ◽  
Body Weight Gain ◽  
Skinfold Thickness ◽  
The Body ◽  
Control Group ◽  
Percentage Body Fat ◽  
Overweight Women ◽  
Body Weights

Previously, we have found that the addition of L-ascorbic acid to chitosan enhanced the reduction in body weight gain in guinea pigs fed a high-fat diet. We hypothesized that the addition of L-ascorbic acid to chitosan would accelerate the reduction of body weight in humans, similar to the animal model. Overweight subjects administered chitosan with or without L-ascorbic acid for 8 weeks, were assigned to three groups: Control group (N = 26, placebo, vehicle only), Chito group (N = 27, 3 g/day chitosan), and Chito-vita group (N = 27, 3 g/day chitosan plus 2 g/day L-ascorbic acid). The body weights and body mass index (BMI) of the Chito and Chito-vita groups decreased significantly (p < 0.05) compared to the Control group. The BMI of the Chito-vita group decreased significantly compared to the Chito group (Chito: -1.0 kg/m2 vs. Chito-vita: -1.6 kg/m2, p < 0.05). The results showed that the chitosan enhanced reduction of body weight and BMI was accentuated by the addition of L-ascorbic acid. The fat mass, percentage body fat, body circumference, and skinfold thickness in the Chito and Chito-vita groups decreased more than the Control group; however, these parameters were not significantly different between the three groups. Chitosan combined with L-ascorbic acid may be useful for controlling body weight.

Hand-assisted laparoscopic nephrectomy in morbidly obese patients

2020 ◽  
Vol 99 (6) ◽  
pp. 271-276
Keyword(s):  
Body Weight ◽  
Surgical Technique ◽  
Blood Loss ◽  
Hospital Stay ◽  
Kidney Cancer ◽  
The Body ◽  
Laparoscopic Nephrectomy ◽  
Morbidly Obese ◽  
Obese Patients ◽  
Morbid Obese

Introduction: Prevalence of obesity is 30 % in the Czech Republic and is expected to increase further in the future. This disease complicates surgical procedures but also the postoperative period. The aim of our paper is to present the surgical technique called hand-assisted laparoscopic nephrectomy (HALS), used in surgical management of kidney cancer in morbid obese patients with BMI >40 kg/m2. Methods: The basic cohort of seven patients with BMI >40 undergoing HALS nephrectomy was retrospectively evaluated. Demographic data were analyzed (age, gender, body weight, height, BMI and comorbidities). The perioperative course (surgery time, blood loss, ICU time, hospital stay and early complications), tumor characteristics (histology, TNM classification, tumor size, removed kidney size) and postoperative follow-up were evaluated. Results: The patient age was 38−67 years; the cohort included 2 females and 5 males, the body weight was 117−155 kg and the BMI was 40.3−501 kg/m2. Surgery time was 73−98 minutes, blood loss was 20−450 ml, and hospital stay was 5−7 days; incisional hernia occurred in one patient. Kidney cancer was confirmed in all cases, 48–110 mm in diameter, and the largest removed specimen size was 210×140×130 mm. One patient died just 9 months after the surgery because of metastatic disease; the tumor-free period in the other patients currently varies between 1 and 5 years. Conclusion: HALS nephrectomy seems to be a suitable and safe surgical technique in complicated patients like these morbid obese patients. HALS nephrectomy provides acceptable surgical and oncological results.

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