scholarly journals Load carriage, human performance, and employment standards

2016 ◽  
Vol 41 (6 (Suppl. 2)) ◽  
pp. S131-S147 ◽  
Author(s):  
Nigel A.S. Taylor ◽  
Gregory E. Peoples ◽  
Stewart R. Petersen
Keyword(s):  
Work Performance ◽  
Human Performance ◽  
Performance Testing ◽  
The Body ◽  
Load Carriage ◽  
Physical Endurance ◽  
Physiological Strain ◽  
Employment Standards ◽  
Heavy Loads ◽  
External Loads

The focus of this review is on the physiological considerations necessary for developing employment standards within occupations that have a heavy reliance on load carriage. Employees within military, fire fighting, law enforcement, and search and rescue occupations regularly work with heavy loads. For example, soldiers often carry loads >50 kg, whilst structural firefighters wear 20–25 kg of protective clothing and equipment, in addition to carrying external loads. It has long been known that heavy loads modify gait, mobility, metabolic rate, and efficiency, while concurrently elevating the risk of muscle fatigue and injury. In addition, load carriage often occurs within environmentally stressful conditions, with protective ensembles adding to the thermal burden of the workplace. Indeed, physiological strain relates not just to the mass and dimensions of carried objects, but to how those loads are positioned on and around the body. Yet heavy loads must be borne by men and women of varying body size, and with the expectation that operational capability will not be impinged. This presents a recruitment conundrum. How do employers identify capable and injury-resistant individuals while simultaneously avoiding discriminatory selection practices? In this communication, the relevant metabolic, cardiopulmonary, and thermoregulatory consequences of loaded work are reviewed, along with concomitant impediments to physical endurance and mobility. Also emphasised is the importance of including occupation-specific clothing, protective equipment, and loads during work-performance testing. Finally, recommendations are presented for how to address these issues when evaluating readiness for duty.

Design of Compliant Bamboo Poles for Carrying Loads

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Karna Potwar ◽  
Jeffrey Ackerman ◽  
Justin Seipel
Keyword(s):  
Low Cost ◽  
Material Design ◽  
The Body ◽  
Load Carriage ◽  
Design Parameters ◽  
Beam Model ◽  
Load Carrying ◽  
Predictive Design ◽  
Force Reduction ◽  
Heavy Loads

Carriage of heavy loads is common in developing countries and can impart large repetitive forces on the body that could lead to musculoskeletal fatigue and injury. Compliant bamboo poles have been used to carry heavy loads in Asia for generations and could be a low-cost, sustainable, and culturally acceptable way to minimize the forces acting on the body during load carriage. Experimental evidence of running with a 15 kg load suspended from a pair of compliant poly(vinyl chloride), or PVC, poles shows that the poles act as a vibration-isolating suspension, which can reduce the peak forces on the body during locomotion. However, it is currently not well-understood how to design and optimize poles for load carrying such that the peak forces on the body are minimized during carrying. Further, current users of bamboo poles do not have a reliable way to measure forces on the body and so cannot empirically optimize their poles for force reduction. Our objective is to determine the geometric and material design parameters that optimize bamboo poles for load carriage and to develop recommendations that could make it easier for load carriers to fabricate well-suited poles. Our approach is to synthesize a predictive model of walking and running from the field of biomechanics, which can predict the peak forces on the body as a function of pole stiffness, with a bending beam model of the bamboo pole that relates pole geometry and material to the effective pole stiffness. We first check our model's ability to predict the experimental results from a well-established study with PVC poles. We then extend the predictive design study to include a wider range of stiffness values and pole geometries that may be more effective and realistic for practical load carrying situations. Based on stiffness, deflection, strength, and pole mass design constraints, we specify an appropriate range of dimensions for selecting bamboo poles to carry a 15 kg load. The design methodology presented could simplify the selection and design of bamboo carrying poles in order to reduce the likelihood of musculoskeletal injury.

scholarly journals The Evolution of Blood Flow Restricted Exercise

2021 ◽  
Vol 12 ◽  
Author(s):  
Eduardo D. S. Freitas ◽  
Murat Karabulut ◽  
Michael G. Bemben
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Flow Restriction ◽  
Alternative Approach ◽  
Safe Technique ◽  
Mechanisms Of Adaptation ◽  
Artery Disease ◽  
Heavy Loads ◽  
And Function ◽  
External Loads

The use of blood flow restricted (BFR) exercise has become an accepted alternative approach to improve skeletal muscle mass and function and improve cardiovascular function in individuals that are not able to or do not wish to use traditional exercise protocols that rely on heavy loads and high training volumes. BFR exercise involves the reduction of blood flow to working skeletal muscle by applying a flexible cuff to the most proximal portions of a person’s arms or legs that results in decreased arterial flow to the exercising muscle and occluded venous return back to the central circulation. Safety concerns, especially related to the cardiovascular system, have not been consistently reported with a few exceptions; however, most researchers agree that BFR exercise can be a relatively safe technique for most people that are free from serious cardiovascular disease, as well as those with coronary artery disease, and also for people suffering from chronic conditions, such as multiple sclerosis, Parkinson’s, and osteoarthritis. Potential mechanisms to explain the benefits of BFR exercise are still mostly speculative and may require more invasive studies or the use of animal models to fully explore mechanisms of adaptation. The setting of absolute resistive pressures has evolved, from being based on an individual’s systolic blood pressure to a relative measure that is based on various percentages of the pressures needed to totally occlude blood flow in the exercising limb. However, since several other issues remain unresolved, such as the actual external loads used in combination with BFR, the type of cuff used to induce the blood flow restriction, and whether the restriction is continuous or intermittent, this paper will attempt to address these additional concerns.

Body Vibrations of a Legged Walking Machine

1992 ◽  
Author(s):  
Xiaochun Gao ◽  
Shin-Min Song
Keyword(s):  
The Body ◽  
Robotic Systems ◽  
Force Distribution ◽  
Walking Machine ◽  
Foot Force ◽  
Robot Hands ◽  
Machine Systems ◽  
External Loads ◽  
Wheeled Vehicles ◽  
Quadrupedal Walking

Abstract Unlike in wheeled vehicles, compliance in walking machine systems changes due to the variation of leg geometry, as its body proceeds. This variation in compliance will cause vibration, even if external loads remain constant. A theory is thus developed to predict the body vibrations of a walking machine during walking. On the other hand, dynamic foot forces under body vibrations can be computed by application of the existing numerical methods. As an example, the body vibrations of a quadrupedal walking chair under different walking conditions are simulated in terms of the developed theory. The results show that the influence of body vibrations on the foot force distribution is essential and, in some cases, the walking chair may lose its stability due to its body vibrations, even though it is identified to be stable in a quasi-static analysis. The developed theory can also be extended to other similar multi-limbed robotic systems, such as multi-fingered robot hands.

Regulating and manipulating the corporeal functions of women academics through political rationality

2019 ◽  
Vol 11 (4) ◽  
pp. 698-718 ◽  
Author(s):  
Nurdiana Gaus
Keyword(s):  
Higher Education ◽  
Public Management ◽  
Work Performance ◽  
New Public Management ◽  
The Body ◽  
Control Mechanisms ◽  
Women Academics ◽  
Content Type ◽  
Audit Culture ◽  
The Government

Purpose The purpose of this paper is to examine the impacts of the politicisation of women academics body in higher education as a result of the implementation of audit culture of new public management. Design/methodology/approach The research was conducted in Indonesian universities, by conducting interviews to collect data from 20 women academics from two universities in eastern regions of Indonesia. Findings The impacts of audit culture on women academics’ body in this study can be understood from the constraints told by them, reflected on the creation of several types of bodies. Research limitations/implications This paper, though, has some limitations in terms of the inclusion of only women academics, exclusion of male academics and of their limitations of addressing important constructs to elaborate the politicisation of the women body, such as culture, religion, patriarchy, and academic tribes and territories. Practical implications The results of this study are important for the policy maker of Indonesia to take into account “gender perspective” on research productivity and publication policy to effectively obtain the political objectives of the government. For higher education in Indonesia, the result of this study may give an indication of the importance to establish different and distinctive standards of work performance evaluation on research and publication for female and male academics. Originality/value The analysis of this issue is framed within the bipolar diagram of power that seeks to gain political-economic function of the body (bio-power), via a set of control mechanisms of sovereign power to regulate and manipulate the population (bio-politics), developed by Foucault (1984).

Effect of Load Carriage on the Backpack Vibration System

2012 ◽  
Vol 165 ◽  
pp. 295-299 ◽  
Author(s):  
Sharifah Alwiah Abdul Rahman ◽  
Azmin Sham Rambely ◽  
Rokiah Rozita Ahmad
Keyword(s):  
Body Weight ◽  
Fourier Series ◽  
The Body ◽  
Load Carriage ◽  
Spring Stiffness ◽  
Vibration System ◽  
Trunk Motion ◽  
Spring System ◽  
And Performance ◽  
Mass Spring

Vibration causes many problems in human health, comfort and performance. While walking with a backpack, movement of the backpack relative to the body causes a vibration which behaves like a spring that moves up and down following the motion of the body. In order to analyse the backpacks response to trunk motion, a backpack vibration system has been developed in this study. A model of a backpack-human trunk system, which is represented by a mass-spring system with a damper, and a Fourier series as an external force, is used to describe the motion of the vibration system. The vibration system was analysed using constant values of damping and spring stiffness (c=1 andk= 5) but with different values of the mass of the backpack. Increasing the mass of the backpack from 10% of body weight to 15 and 20% of body weight increased the amplitude of both the displacement and velocity of the backpack vibration system. However, the frequencies of the vibration system decreased as the mass of the backpack increased.

How to Carry Loads Economically: Analysis Based on a Predictive Biped Model

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Tong Li ◽  
Qingguo Li ◽  
Tao Liu ◽  
Jingang Yi
Keyword(s):  
Relative Motion ◽  
Energy Cost ◽  
Interaction Force ◽  
The Body ◽  
Additional Energy ◽  
Load Carrying ◽  
Walking Motion ◽  
Carrier Interaction ◽  
Heavy Loads ◽  
And Control

Abstract Carrying heavy loads costs additional energy during walking and leads to fatigue of the user. Conventionally, the load is fixed on the body. Some recent studies showed energy cost reduction when the relative motion of the load with respect to the body was allowed. However, the influences of the load's relative motion on the user are still not fully understood. We employed an optimization-based biped model, which can generate human-like walking motion to study the load–carrier interaction. The relative motion can be achieved by a passive mechanism (such as springs) or a powered mechanism (such as actuators), and the relative motion can occur in the vertical or fore-aft directions. The connection between the load and body is added to the biped model in four scenarios (two types × two directions). The optimization results indicate that the stiffness values affect energy cost differently and the same stiffness value in different directions may have opposite effects. Powered relative motion in either direction can potentially reduce energy cost but the vertical relative motion can achieve a higher reduction than fore-aft relative motion. Surprisingly, powered relative motion only performs marginally better than the passive conditions at similar peak interaction force levels. This work provides insights into developing more economical load-carrying methods and the model presented may be applied to the design and control of wearable load-carrying devices.

scholarly journals Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Javier Zaragoza ◽  
Grant Tinsley ◽  
Stacie Urbina ◽  
Katelyn Villa ◽  
Emily Santos ◽  
...  
Keyword(s):  
Physical Performance ◽  
Linear Models ◽  
Dynamic Testing ◽  
Collegiate Athletes ◽  
Performance Testing ◽  
The Body ◽  
Double Blind ◽  
Movement Accuracy ◽  
Beneficial Effects ◽  
Before And After

Abstract Background A limited amount of research has demonstrated beneficial effects of caffeine and theanine supplementation for enhancement of mental performance. The purpose of this investigation was to determine whether the acute ingestion of a supplement containing caffeine, theanine and tyrosine improves mental and physical performance in athletes. Methods Twenty current or former male collegiate athletes (age: 20.5 ± 1.4 y; height: 1.82 ± 0.08 m; weight: 83.9 ± 12.6 kg; body fat: 13.8 ± 5.6%) completed this randomized, double-blind, placebo-controlled crossover trial. After familiarization, each participant completed two identical testing sessions with provision of a proprietary dietary supplement (SUP) containing caffeine theanine and tyrosine or a placebo (PL). Within each testing session, participants completed assessments of mental and physical performance before and after provision of SUP or PL, as well as after two rounds of exercise. Assessments were performed using a performance testing device (Makoto Arena) that evaluated multiple aspects of mental and physical performance in response to auditory and visual stimuli. Testing was performed both with the body in a static position and during dynamic movement. General linear models were used to evaluate the effects of SUP and PL on performance. Results Changes in movement accuracy during performance assessment were greater following SUP ingestion as compared to PL for both static and dynamic testing (SUP: + 0.4 to 7.5%; PL: − 1.4 to 1.4% on average; p < 0.05). For dynamic testing, the change in number of targets hit was higher and the change in average hit time was lower with SUP as compared to PL (p < 0.05). However, there were no differences between conditions for the changes in number of targets hit or average hit time during static testing. There were no differences in changes of subjective variables during either condition, and performance measures during the two rounds of exercise did not differ between conditions (p > 0.05). Discussion The present results indicate that a combination of a low-dose of caffeine with theanine and tyrosine may improve athletes’ movement accuracy surrounding bouts of exhaustive exercise without altering subjective variables. Based on this finding, supplementation with caffeine, theanine and tyrosine could potentially hold ergogenic value for athletes in sports requiring rapid and accurate movements. Trial registration NCT03019523. Registered 24 January 2017.

Employee learning stimulated by manager-as-coach

2020 ◽  
Vol 32 (8) ◽  
pp. 627-640
Author(s):  
Paul Lyons ◽  
Randall Bandura
Keyword(s):  
Work Performance ◽  
Relevant Literature ◽  
Growth Mindset ◽  
The Body ◽  
Theory And Practice ◽  
Individual Development ◽  
Learning Orientation ◽  
Content Type ◽  
Motivational Support ◽  
Employee Learning

Purpose The purpose of this paper is to explore the ways a manager in a coaching role may influence employees to embrace a learning orientation based upon the growth mindset. Conceptual in nature, this paper uses recent research, interpretations, explanations and suggestions to propose how manager-as-coach can informally and formally apply basic interventions to assist employee learning and change. Design/methodology/approach Based upon a review of relevant literature of theory and practice using several search tools, the authors have isolated a few critical areas to explore to include role of the coach, performance appraisal – the stimulus for manager-as-coach interaction with an employee, feedback orientation and environment, the growth mindset and learning orientation and the dynamics of self-regulated learning. Information from these areas is integrated to inform practitioners of approaches to take in a manager-as-coach role. Findings Included for each of the main segments presented are specific, practitioner “Commitment advice/action agendas” for manager-as-coach to stimulate and guide employee learning. These agendas contribute sound, practical information to the body of information concerned with manager-as-coach. Originality/value A contribution this work makes is to propose how learning orientation and the growth mindset are intertwined to the extent they assist the manager-as-coach supply the motivational support for employee learning. The resultant learning may lead to one or more of: improved work performance, individual development, attitudes toward learning and increased employee commitment or engagement.

DYNAMIC LOADS ON THE DRIVE SHAFT BEARINGS OF A SWASH PLATE AXIAL PISTON PUMP WITH CONICAL CYLINDER BLOCK

2004 ◽  
Vol 27 (4) ◽  
pp. 309-318
Author(s):  
M.K. Bahr Khalil ◽  
J.V. Svoboda ◽  
R.B. Bhat
Keyword(s):  
The Body ◽  
Drive Shaft ◽  
Dynamic Loads ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Static And Dynamic Characteristics ◽  
Swash Plate ◽  
Variable Displacement ◽  
Heavy Loads ◽  
Axial Piston

Variable displacement swash plate pumps are invariably used under conditions that involve heavy loads with variable flow demands. Swash plate pumps with conical cylinder blocks are now widely used in view of their good static and dynamic characteristics. However, drive shafts of these pumps experience dynamic loads due to the pressure forces transmitted through the body of the conical cylinder block to the supporting bearings. Dynamics of such rotating mechanism are quite interesting and should be considered in the design process of the drive shaft and the supporting bearings. A mathematical model is formulated for a 9-piston swash plate pump with conical cylinder block in order to evaluate the dynamic loads on the drive shaft. Results are presented and discussed.

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