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Most exoskeletons designed to assist users in load-bearing tasks face a mechanical dilemma in their conception. Designers may find a compromise between stiff active actuators-based architectures which are powerful but bulky and compliant actuator-based designs which are much less assistive but less constraining for users. This article presents a new open-source simulation-based design tool and a human-centered method that lets orthosis designers explore different device configurations and evaluate some performance criteria. This framework was applied in three different young-adult subjects. The effects of design personalization on user morphology and gait were studied. First, an ankle–foot orthosis designed to support a 20 kg backpack was defined according to the user's height, weight, and walking speed. Then, a simulation of the subjects fitted with their customized design walking at a self-selected speed on flat ground carrying this additional load was performed. First, the results showed that the designed method inspired by natural joint stiffness behavior provided viable personalized mechanisms. Second, significant reductions in peak joint torque and mean joint activity were observed when comparing muscle-generated torques while the subject was wearing the 20 kg backpack with ankle–foot orthoses on both legs or without. Finally, it shows the value of an open-access tool for exploring the coupling of passive and active actuators to generate lighter and more compliant designs. [ABSTRACT FROM AUTHOR]

In this paper, a new application of State-Dependent Riccati Equation (SDRE) is proposed as a framework to design a robust controller for the system of multiple cooperative arms with parametric uncertainties. The cooperative arms are tracking a trajectory holding a mass. Transforming the complicated robust control design to a parallel auxiliary sub-optimal design leads to a considerable facility in design and extensive applicability specifically for complex systems. An auxiliary system with a modified performance criterion is first introduced. The modification in performance criterion is through the incorporation of uncertainties in upper bounds obtained from stability proof. Uncertain State-Dependent Coefficient (USDC) regarding joints' friction for the robotic system is utilized to obtain the auxiliary USDC structure. Two control policies are considered: independent control of each arm and simultaneous control of overall multiple manipulators. The sub-optimal problem for the auxiliary system is solved. The achieved optimal control input for the auxiliary system is the robust input for the equivalent uncertain system. Simulation results in both policies verify the effectiveness and satisfactory robustness (30%) of the proposed scheme in load carrying. Moreover, considering the same trajectory, payload, and design parameters controlling the overall robotic system is superior with respect to separately controlling each arm. Finally, a comparison study is presented for the proposed scheme and Mixed SDRE-SMC (MiSS) for the overall robotic system carrying the same payload through simulation results. [ABSTRACT FROM AUTHOR]

Background and Aim: Patellofemoral pain syndrome (PFPS) is a common musculoskeletal disorder with a high prevalence among military personnel. Changing the movement pattern and applying loads can lead to an increase in postural sway and contribute to the development of patellofemoral pain syndrome in military personnel. Therefore, the aim of the present study is to comparison of knee valgus angle and the effect of carrying a military backpack on postural sway in the military with and without patellofemoral pain syndrome. Methods: In this case-control study, 21 military personnel with patellofemoral pain syndrome participated voluntarily with Convenience Judgmental Sampling method and 21 healthy military personnel with the case group matching method. The indices of postural sway, including the path length, the standard deviation of medial-lateral sway (M-L), and the standard deviation of anterior-posterior sway (A-P) were measured using the Zebris pressure distribution device in two situations with and without carrying a military backpack. Also, the knee valgus angle was assessed during the single-leg squat test. To analyze the data, an independent t-test and paired sample t-test with a significance level of 0.05 were used in SPSS software version 23. Results: The results of the independent t-test showed that knee valgus angle, path length, SD(M-L), SD (AP), in both positions with and without carrying a military backpack showed a significant increase in patellofemoral pain syndrome group in comparison with the healthy military (P<0.05). Comparing the changes in the center of pressure variables during the static balance test, and static balance with carrying a military backpack, there were also significant changes between the two positions (P<0.05). Conclusion: According to the results, military with patellofemoral pain syndrome who had an increase in knee valgus angle had more postural sway and changes in postural sway indices compared to the healthy military, which could be caused by changing posture control strategies and changing the movement pattern of the military with patellofemoral pain syndrome. It is necessary to pay attention to these changes in providing an appropriate treatment plan for preventing re-injury and secondary changes in military suffering from patellofemoral pain syndrome. [ABSTRACT FROM AUTHOR]

The increasing necessity of load-carrying activities has led to greater human musculoskeletal damage and an increased metabolic cost. With the rise of exoskeleton technology, researchers have begun exploring different approaches to developing wearable robots to augment human load-carrying ability. However, there is a lack of systematic discussion on biomechanics, mechanical designs, and augmentation performance. To achieve this, extensive studies have been reviewed and 108 references are selected mainly from 2013 to 2022 to address the most recent development. Other earlier 20 studies are selected to present the origin of different design principles. In terms of the way to achieve load-carrying augmentation, the exoskeletons reviewed in this paper are sorted by four categories based on the design principles, namely load-suspended backpacks, lower-limb exoskeletons providing joint torques, exoskeletons transferring load to the ground and exoskeletons transferring load between body segments. Specifically, the driving modes of active and passive, the structure of rigid and flexible, the conflict between assistive performance and the mass penalty of the exoskeleton, and the autonomy are discussed in detail in each section to illustrate the advances, challenges, and future trends of exoskeletons designed to carry loads. [ABSTRACT FROM AUTHOR]

Cantilever is a structural form that extends horizontally and is supported by one end and free on the other while the load is distributed equally, initiated by the use of bridges and balconies in the buildings. The power of Cantilevers with its different designs is spreading throughout the world via various perspectives since it increases the ability of design creativity and gives proper solutions. However, from that point forward, a research gap that has been found missing relating the structural challenges and how it affects the design and the decisions taken by the clients/ owners paying budgets on such type of structural additions that may not achieve the 100% building safety. Lack of knowing the proper building technologies may lead to reduce limits of innovation, that resulted in building repetitive traditional prototype without remarkable decisions. This paper therefore aims to detect the new building technologies that enable architects to design a cantilever in their projects, helping the design and the load carrying problems and highlight the exceptional designs that challenges the attractive force and establish a flying structure. In order to achieve the mentioned aim, the paper will start presenting a literature review based on a desk research theories and methods of construction were used to clearly explains our topic "the power of cantilevers in contemporary arch." Supported with diverse analysis of Frank Lloyd Wright, Zaha Hadid, and Knight Architects. [ABSTRACT FROM AUTHOR]

Reinforced concrete structure systems are usually designed as frame or shear wall-frame systems. It is possible to reduce the deformation and displacement in the system by increasing the structural stiffness. Besides, large displacements on the floors caused by horizontal load are damped by the cracks in these walls. The present paper aims to examine the effects of materials used in the wall construction as well as thickness of the plaster on the behavior of infill walls under cyclic loads. In order to investigate the above mentioned effects, three Infill walls that were produced from three different materials namely, horizontal hollow bricks, pumice blocks and aerated concrete blocks were tested in three setups (without plaster, with 1 cm plaster and 2.5 cm plaster on it). In order to determine pure wall contribution, the infill walls were placed in a steel frame test set-up which was hinged from all four corners and were then exposed to cyclic loads taking into account the displacement controlled loading protocol proposed in FEMA 461. Right after applying the plaster to the infill walls, load carrying and energy dissipation capacities of the walls were examined comparatively. Loaddisplacement, backbone curve and cumulative dissipated energy curves of each infill walls are generated using the data collected from the experiments and the infill walls behaviors are graphically explained. Test results showed that existence and thickness of plaster significantly affected cyclic behavior of the test walls by increasing energy dissipation capacities and load carrying capacities. [ABSTRACT FROM AUTHOR]

Abstract: Allostatic load describes the interplay between energetic demand and availability and is highly context dependent, varying between seasons and life‐history stages. When energy demands exceed physiological set points modulated by glucocorticoid hormones, individuals may experience allostatic overload and transition between stages in sub‐optimal physiological states. Corticosterone, the major glucocorticoid hormone regulating energy expenditure in birds, is incorporated into growing feathers (CORTf), and it has been suggested that CORTf reflects long‐term records of allostatic load during feather growth. However, relationships between allostatic load and CORTf have not been adequately evaluated. If such relationships exist, the use of CORTf to investigate cross‐seasonal effects could provide novel insights into impacts of past allostatic load and/or overload events. We tested whether experimental increases in daily workload during two adjacent life‐history stages would be reflected in CORTf levels, and examined if CORTf levels reflected either current energetic demand or allostatic load prior to feather growth. Daily workloads in female mallard Anas platyrhynchos ducklings were increased over a 6‐week period using physical obstacles and/or carrying back‐mounted weights. We measured daily energy expenditure, growth, body mass, and CORTf in growing ducklings. Then, we induced feather moult and reapplied combinations of workload treatments for an additional 6 weeks to investigate whether effects of past energetic demands would be detected in future CORTf levels. Ducklings confronted with higher workloads during development had reduced body mass, growth rates and consequently higher daily energy expenditure and CORTf values compared to controls. When ducklings were fully developed, CORTf patterns in birds re‐exposed to workload treatments reflected only current, rather than past, energetic demands. However, under allostatic overload conditions, past levels of CORTf were positively associated with CORTf in the subsequent moult. Our study confirms the previously untested assumption that CORTf reflects energetic demand during the period of feather growth in a precocial bird. We show that allostatic overload conditions early in life, which temporarily suppress growth, can be detected using CORTf, an event potentially missed in studies which rely solely on measures of body condition alone. We suggest that CORTf can provide a valuable biomarker of allostatic load and overload conditions during the period of feather growth, but highlight how context should be considered for studies using CORTf to investigate influences of carryover effects. Our study contributes to building a physiological foundation to inform interpretations of ecological patterns using CORTf. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

In the Everest valley of Nepal, because of the rugged mountain terrain, roads are nothing more than dirt paths and all material must be conveyed on foot. The Nepalese porters routinely carry headsupported loads, which often exceed their body mass, over long distances up and down the steep mountain footpaths. In Africa, women transport their loads economically thanks to an energy-saving gait adaptation. We hypothesized that the Nepalese porters may have developed a corresponding mechanism. To investigate this proposition, we measured the mechanical work done during level walking in Nepalese porters while carrying different loads at several speeds. Our results show that the Nepalese porters do not use an equivalent mechanism as the African women to reduce work. In contrast, the Nepalese porters develop an equal amount of total mechanical work as Western control subjects while carrying loads of 0 to 120% of their body mass at all speeds measured (0.5- 1.7 m s−1), making even more impressive their ability to carry loads without any apparent mechanically determined tricks. Nevertheless, our results show that the Nepalese porters have a higher efficiency, at least at slow speeds and high loads. [ABSTRACT FROM AUTHOR]

This study investigates whether a flexible pole can be used as an energy-saving method for humans carrying loads. We model the carrier and pole system as a driven damped harmonic oscillator and predict that the energy expended by the carrier is affected by the compliance of the pole and the ratio between the pole's natural frequency and the carrier's step frequency. We tested the model by measuring oxygen consumption in 16 previously untrained male participants walking on a treadmill at four step frequencies using two loaded poles: one made of bamboo and one of steel. We found that when the bamboo pole was carried at a step frequency 20% greater than its natural frequency, the motions of the centers of mass of the load and carrier were approximately equal in amplitude and opposite in phase, which we predicted would save energy for the carrier. Carrying the steel pole, however, resulted in the carrier and loads oscillating in phase and with roughly equal amplitude. Although participants were less economical using poles than predicted costs using conventional fixed-load techniques (such as backpacks), the bamboo pole was on average 5.0% less costly than the steel pole. When allowed to select their cadence, participants also preferred to carry the bamboo pole at step frequencies of ~2.0 Hz. This frequency, which is significantly higher than the preferred unloaded step frequency, is most economical. These experiments suggest that pole carriers can intuitively adjust their gaits, or choose poles with appropriate compliance, to increase energetic savings. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate the effects of load on the net moment response at the L5/S1 joint during simulated slip events. Six young individuals were instructed to take one step with a handheld load. Sudden floor movement was randomly introduced to simulate unexpected slips. Different loads conditions (0%, 10%, 20%, 30% of body weight) were introduced at random. Three-dimensional net moments at the L5/S1 joint were computed via downward inverse dynamic model. Peak joint moment generated at 30% load level was found to be significantly higher compared to no-load condition. No peak moment differences were found among no-load, 10% or 20% load levels. Additionally, the findings from this study indicated a flexiondominant net L5/S1 joint moment pattern during motion phase associated with slip-induced falls. [ABSTRACT FROM AUTHOR]

ABSTRACT Nano-calcium borate (NCB) with an average particle size of about 70 nm was synthesised via ethanol supercritical fluid drying technique, and the morphology and microstructures of as-prepared particles were characterised by means of scanning electron microscope (SEM, JEOL LTD., Tokyo, Japan) and X-ray powder diffraction. The friction and wear behaviour of the NCB as additive in lithium grease were evaluated with an Optimol-SRV IV (Optimol Instruments Prüftechnik GmbH, Munich, Germany) oscillating friction and wear tester (SRV tester). The morphology and surface composition of the worn surfaces of lower discs after SRV test were analysed by SEM and X-ray photoelectron spectroscopy (XPS, Physical Electronics, Inc., USA). The result demonstrated that the anti-wear and load-carrying capacities of the lithium grease were significantly improved, and the friction coefficient of the lithium grease decreased with the addition of NCB additive. The analytical results of XPS indicate that the good tribological performance of NCB is attributable to the formation of a boundary lubrication film composed of deposited NCB and the tribochemical reaction products such as B2O3, CaO and iron oxides on the rubbing surface. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of the experiment was to evaluate the effect of 4-h load carrying (packing) on donkeys administered with ascorbic acid (AA) during the harmattan season. Six donkeys administered orally with ascorbic acid (200 mg/kg) and subjected to packing served as experimental animals, while six others given only distilled water served as control animals. The rectal temperature (RT) of each donkey and dry-bulb temperature (DBT) and relative humidity (RH) of the research pen were recorded at 0600 hours pre-packing; while post-packing, the values were obtained at 1430, 1600 and 1800 hours. The DBT values (ranges) recorded before, during and after packing were 13.7 ± 1.3 °C (11-15 °C), 28.4 ± 1.0 °C (22.7-30.3 °C) and 30.6 ± 3.0 °C (19.8-45 °C), respectively. The highest temperature-humidity index (THI) of 83.4 ± 6.9 was obtained at 1430 hours after packing, and the value decreased to 64.2 ± 5.8 at 1800 hours. The thermal environmental conditions were outside the thermoneutral zone for the donkeys. The RT values recorded immediately after packing did not differ ( P > 0.05) in experimental and control donkeys; but at 1600 and 1800 hours, values obtained in control donkeys (38.48 ± 0.12 and 38.12 ± 0.12 °C, respectively) were significantly higher ( P < 0.05) than those recorded in experimental donkeys (38.16 ± 0.14 and 37.85 ± 0.14 °C, respectively). In conclusion, administration of ascorbic acid reduced the rise in RT due to packing and may be of value in the amelioration of adverse effects of heat stress associated with work in donkeys. [ABSTRACT FROM AUTHOR]

This cross-sectional study investigated the use of schoolbags and the prevalence of musculoskeletal symptoms among a sample of 307 Iranian primary school children aged 7–12 years. The average load carried by the children was 2.9 kg (representing on average 10.1% of the child's body weight). Most children chose to carry the schoolbag across two shoulders, although significant numbers also carried it on one shoulder or in the hand. Although the amount of load carried by school children was within the currently suggested load limit of 10% to 15% of the child's body weight, the prevalence of musculoskeletal problems was very high among the study population. Multiple logistic regression models indicated that the method of carrying the schoolbag was significantly associated with hand/wrist and shoulder symptoms, and that the time spent carrying a schoolbag was associated with hand/wrist and upper back symptoms. Schoolbag weight (expressed as a percentage of body weight) was only associated with hand/wrist symptoms. The results suggest that the current recommended weight limit may not be appropriate for school children in primary school, and that guidelines ought to consider factors other than relative schoolbag weight that influence the use of schoolbags among this age group. Practitioner Summary:The carrying of schoolbags by primary school children and their musculoskeletal symptoms were investigated. The results provide evidence that the current weight limit may not be appropriate for younger school children, and that such guidelines should consider a broader combination of the factors that influence the use of schoolbags. [ABSTRACT FROM PUBLISHER]

Different from conventional generation, the renewable resource, such as wind or solar generation, is energy limited and intermittent. It is challenging to identify the capacity credit of renewable generation. A new method has been proposed in this paper to determine the capacity credit for renewable resource in the framework of resource adequacy. An optimization model is developed first to calculate the minimum resource procurement based on the system loss of load expectation criterion. Then, renewable generation is added into the generation portfolio to identify the new resource procurement. The capacity credit of the renewable generation is the reduction in the procurement requirement for the conventional resource. The proposed model and method are demonstrated on the IEEE Reliability Test System system. [ABSTRACT FROM AUTHOR]

"Limit Cycle Walking" is a relatively new paradigm for the design and control of two-legged walking robots. It states that achieving stable periodic gait is possible without locally stabilizing the walking trajectory at every instant in time, as is traditionally done in most walking robots. Well-known examples of Limit Cycle Walkers are the Passive Dynamic Walkers, but recently there are also many actuated Limit Cycle Walkers. Limit Cycle Walkers generally use less energy than other existing bipeds, but thus far they have not been as versatile. This paper focuses on one aspect of versatility: walking speed. We study how walking speed can be varied, which way is energetically beneficial and how walking speed affects a walker's ability to handle disturbances (that is, disturbance rejection). The study is performed using one prototype and one simulation model. The speed of these two walkers is adapted by changing three parameters: the amount of ankle push-off, upper body pitch and step length. The study has resulted in four conclusions. (1) Steady-state speeds between 0.24 and 0.68 m s-1 (for a 0.6 m leg length) were obtained, with loss of stability determining the lower limit and actuation limits determining the upper limit. This result shows the applicability of Limit Cycle Walking for versatile walking machines. (2) For any speed, powering the gait by leaning the body forward costs less energy than using ankle push-off. (3) In contrast to the apparent tradeoff between speed and stability in traditional walking robots, in Limit Cycle Walking we find that increasing the walking speed, independent of how this is done, automatically results in an increasing disturbance rejection. (4) A combination of feedforward actuation adjustment and step-to-step feedback from walking speed shows that it is possible to change walking speed in only a few steps and maintain a desired speed when performing tasks such as carrying loads and walking on slopes. In particular, this fourth conclusion underlines the applicability of the concept of Limit Cycle Walking for versatile two-legged walking machines. [ABSTRACT FROM AUTHOR]

Slip resistance measurements of shoes and floors are used to evaluate the potential for slip and fall injuries. These measurements are believed to have increased validity when they more closely reflect actual heelstrike biomechanics during locomotion. The purpose of this study was to describe heelstrike kinematics during load carrying to provide data towards improved slip resistance testing. Foot kinematics during load carrying (unladen and carrying from 0 to 13.5 kg) at various cadences (70, 90, 100 steps/min) was recorded. Measures before, during and after heelstrike were analysed. Cadence was an important predictor for all variables measured, associated with changes from 13% to over 100%. The load carried was an important predictor for only the heel slip distance after heelstrike, but this effect needs to be investigated further. These results can be used to improve the fidelity of slip resistance measurements, which is critical to reduce slip and fall injuries in the workplace or during activities of daily living. [ABSTRACT FROM AUTHOR]

We examined the changes in muscle energy use in guinea fowl running at 1.5 m s-1 either unloaded, or carrying trunk loads equal to 23% of body mass, or loads on their distal legs equal to a total of S % of body mass. We estimated muscle energy use by measuring blood flow to all of the leg muscles using injected microspheres. Total blood flow to the leg muscles increased by approximately 15% under both loading conditions, which matched the percentage increase in net organismal metabolic rate. Significant increases in energy use (inferred from blood flow) above that found in unloaded birds were found in 12 muscles in trunk-loaded birds, with most of the increases restricted to stance-phase muscles, as predicted. Just three of these muscles, the femerotibialis, the iliotibialis lateralis pars postacetabularis and the fibularis longus accounted for 70% of the increased energy use. Noticeably absent from the group of muscles that increased energy use during trunk loading were several large biarticular muscles that have extensor actions at the hip or ankle, but flexor actions at the knee. We concluded that the low energetic cost of carrying trunk loads in guinea fowl may rely on the activation of a group of muscles that together provide support and propulsion across all the major joints, without producing opposing moments at other joints that could potentially waste energy. The specific leg muscles responsible for the increase in metabolism during trunk loading also suggest that the energy cost of producing mechanical work may be an important determinant of the cost of carrying extra mass on the trunk. During distal-limb loading, eleven leg muscles had significant increases in energy use, but unlike during trunk loading, both stance- and swing-phase muscles had large increases in energy use. This distribution of energy use between stance and swing agrees with the prediction that increased mechanical work determines the cost of limb loading, because a substantial fraction of the increased segmental work during distal-limb loading in guinea fowl has been found to occur during stance. [ABSTRACT FROM AUTHOR]

It is well established that the energy cost per unit distance traveled is minimal at an intermediate walking speed in humans, defining an energetically optimal walking speed. However, little is known about the optimal walking speed while carrying a load. In this work, we studied the effect of speed and load on the energy expenditure of walking. The O2 consumption and CO2 production were measured in ten subjects while standing or walking at different speeds from 0.5 to 1.7 m s-1 with loads from 0 to 75% of their body mass (Mb). The loads were carried in typical trekker’s backpacks with hip support. Our results show that the mass-specific gross metabolic power increases curvilinearly with speed and is directly proportional to the load at any speed. For all loading conditions, the gross metabolic energy cost (J kg-1 m-1) presents a U-shaped curve with a minimum at around 1.3 m s-1. At that optimal speed, a load up to 1/4Mb seems appropriate for long-distance walks. In addition, the optimal speed for net cost minimization is around 1.06 m s-1 and is independent of load. [ABSTRACT FROM AUTHOR]

The complex human processes involved in balance maintenance and fall prevention during normal locomotion are further complicated by load carrying and/or the presence of slippery floors. The goal of this study was to investigate the effect of carrying loads (2-handed method) on gait biomechanics relevant to slips/falls. Participants walked down surfaces of varying inclinations (0°, 5&deg and 10°), while ground reaction forces and body/foot motion were recorded. Three load conditions (no load, 2.3 and 6.8 kg) were included. Load carrying was associated with increases in the peak normal ground reaction force and in the rate of the normal loading phase on the leading foot. Shear ground reaction forces were not affected by load carrying. Changes in the ground reaction forces recorded during load carrying led to reduced required coefficient of friction (RCOF) values, a variable used to rate slip potential. This RCOF reduction is partly due to postural adaptations such as increased knee and hip flexion adopted during load carrying. Furthermore, load carrying was accompanied by slower heel contact heel velocity in the direction of motion. Finally, moments generated at the hip and knee joints were significantly biased towards the extensor and flexor direction, respectively. [ABSTRACT FROM AUTHOR]

Porters in different age groups, 20-29 yr, 30-39 yr, 40-49 yr and 50 yr and above, carried loads of 0,20,30,40,50 and 60 kg, within the range carried by them in their daily work, at a fixed speed of 5 km h−1, the average normal speed of walking with loads. The range of energy expenditure relative to measured maximum oxygen uptake ([Vdot]O2 max) suggests that the maximum permissible loads to be carried at 5kmh−1 by subjects in these age groups are 41,23,21 and 11 kg, respectively. [ABSTRACT FROM PUBLISHER]

In order to determine the effect of loads worn or carried on walking mechanics, 11 men and 11 women were filmed using high speed cinematography as they performed overground walking at 1·78 m/s under five load conditions. The loads included a baseline condition in which subjects carried no added load, and additional loads of approximately 9, 17, 29 and 36 kg consisting of standard military items. The latter two loads were added in the form of a framed rucksack system. Values for several variables frequently used to described temporal and kinematic characteristics of walking were quantified from the film. These included stride length, stride rate, single leg support time, double-support time, swing time and the forward inclination of the trunk. The results of the study demonstrated that the males and females displayed significantly different gait patterns under all load conditions. Not unexpectedly, the females required a higher rate of stepping than the males because of their shorter stride lengths. The results also demonstrated that the walking patterns of both the male and female subjects were affected by the increases in carried load. In general, stride length and swing time decreased while stride rate and double-support time increased with increases in load. There was also an increased forward inclination of the trunk but only for the two heaviest loads which were carried in a rucksack. While the changes in gait characteristics were relatively small for the male subjects, the females were affected to a greater extent thereby demonstrating a greater sensitivity to load magnitude. It was concluded that careful consideration must be given to the absolute loads carried by males and females. Not only is it important for load requirements to be lower for females because of the physiological implications but also because of biomechanical implications and the associated mechanical stresses which must be endured during locomotion. While this study was directed primarily towards military applications, the results should also have implications for load carrying in a variety of situations and environments, including industrial and recreational applications. [ABSTRACT FROM PUBLISHER]

Ninety-three young Chinese men selected at random were involved in the load carrying experiments. They marched at 5 km h−1 carrying loads of 0,15,20,25 and 31 kg for 7 h per day. At this speed the acceptable load to be carried was 20 kg. Under this load 95% of the men had heart rates below 120 btmin"’ while marching and energy metabolism was in balance. Nevertheless, 10-15% of the men were fatigued and felt tired. [ABSTRACT FROM PUBLISHER]

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