Effect of load position on physiological and perceptual responses during load carriage with an internal frame backpack

The purpose of this study was to determine the effect of load position in an internal frame backpack on physiological and perceptual variables. Ten female participants walked on a level treadmill for 10?min carrying 25% of their body weight in a high, central, or low position. The variables measured included oxygen consumption (VO₂), heart rate (HR), respiratory exchange ratio (R), respiratory rate (RR), minute ventilation (VE), and rating of perceived exertion (RPE). VO₂, VE, and RPE were significantly lower in the high position (18.6?±?2.3?ml/kg/min, 31.7?±?5.0?l/min, 2.8?±?0.8, respectively) compared to the low position (22.2?±?3.0?ml/kg/min, 38.6?±?7.5?l/min, 3.7?±?1.0, respectively). HR, R, and RR did not change significantly as the load was moved from the high (129.8?±?16.8, 0.89?±?0.06, 30.3?±?4.2, respectively) to the low position (136.0?±?25.3, 0.92?±?0.04, 33.8?±?5.2, respectively). The results of this study suggest that load placement is an important factor in the physiological and perceptual responses to load carriage, and that packing heavy items high in the backpack may be the most energy efficient method of carrying a load on the back.     

The effects of load placement on the EMG activity of the low back muscles during load carrying by men and women

An electromyographic (EMG) study of the lumbar paraspinal muscles during load carrying was undertaken in a group of 24 healthy subjects, 12 male and 12 female. Two different magnitude loads (10% and 20% of the subject's body weight) and four different carrying positions were compared with walking without an external load. Results indicated changes in back muscle activity showing a significant interaction between load magnitude and carrying position. Compared to walking without an external load, lumbar paraspinal EMG activity showed slight decreases when loads were carried in a backpack position or in the hand ipsilateral to the muscle. EMG activity contralateral to the hand carrying the load was significantly increased. Significant increases occurred when loads were carried anterior to the chest with the arms and a significant difference was found between male and female subjects for this carrying position. These findings have implications for the selection of carrying methods.     

Effect of backpack fit on lung function

Carrying loads close to the trunk with a backpack causes a restrictive type of change in lung function in which Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1?s (FEV₁) are reduced without a corresponding decrement in the FEV₁.FVC^???1 %. It is not known whether this is due to the weight of the load acting on the chest or to the tightness of fit of the shoulder and chest straps and waist belt of the pack harness. This study examined FVC, FEV₁, FEV₁.FVC^???1 %, peak expiratory flow (PEF), forced expiratory flow between 0.2 and 1.2?s (FEF_0.2?–?1.2) after the start of expiration and between 25 and 75% of each FVC (FEF_25?–?75%) in 12 healthy males wearing a 15?kg backpack in which the shoulder and chest straps and hip belt were loosened by 3?cm from a ‘comfort fit’ to achieve a ‘loose pack’ fit (LPF) and tightened by 3?cm from CF to achieve a ‘tight pack’ fit (TPF). In comparison with the control condition of no pack, a loose pack fit significantly reduced FVC (by 3.6%, p?<?0.01), FEV₁ (by 4.3%, p?<?0.01) and FEF_25?–?75% (by 8.4%, p?<?0.01). A tight pack fit significantly reduced FVC (by 8.1%, p?<?0.01) and FEV₁ (by 9.1%, p?<?0.001). It also significantly reduced FEF_0.2?–?1.2 (by 7.3%, p?<?0.05) and FEF_25?–?75% (by 21%, p?<?0.01). In comparison with a loose pack fit, the tight pack fit was associated with a significantly lower FVC (by 4.6%, p?<?0.01), FEV₁ (by 5.0%, p?<?0.01), FEF_25?–?75% (by 13.8%, p?<?0.01) and a fall in FEF_0.2?–?1.2 (by 5.5%). The latter was approaching significance (p?=?0.077). There were no significant changes in FEV₁.FVC^???1% and PEF. It is concluded that tightening the fit of a backpack significantly affects lung function in a manner that is typical of a restrictive change in lung function and is very similar in pattern to that of wearing a loosely fitted loaded backpack. The effect of tightness of fit is additional to that due to the weight of the load alone and may also reduce expiratory flow at low lung volumes.     

Short-term effects of backpack load placement on spine deformation and repositioning error in schoolchildren

Backpack weight of 10–15% has been recommended as an acceptable limit for schoolchildren. However, there is still no clear guideline regarding where the backpack centre of gravity (CG) should be positioned. The changes of spinal curvature and repositioning error when carrying a backpack loaded at 15% of body weight at different CG locations (anterior or posterior at T7, T12 or L3) in schoolchildren were analysed. Both spinal curvature and repositioning error were found to be affected by backpack anterior–posterior position and CG level. A relatively smaller change was observed during anterior carriage with the least change when the backpack CG was positioned at T12. The results also suggested that alternative carriage by changing the backpack position occasionally between anterior and posterior positions might help to relieve the effects of backpack on spine. However, future study is recommended to further substantiate the beneficial effects of alternative carriage on children.

Statement of Relevance: Anteriorly carried backpack with centre of gravity positioned at T12 was shown to induce relatively less effect on spinal deformation and repositioning error in schoolchildren. Changing backpack carriage position occasionally may help to relieve its effects on spinal deformation. The findings are important for ergonomic schoolbag design and determining a proper load carriage method.     

Evaluation of the effect of backpack load and position during standing and walking using biomechanical,physiological and subjective measures

Recommendations on backpack loading advice restricting the load to 10% of body weight and carrying the load high on the spine. The effects of increasing load (0%–5%–10%–15% of body weight) and changing the placement of the load on the spine, thoracic vs. lumbar placement, during standing and gait were analysed in 20 college-aged students by studying physiological, biomechanical and subjective data. Significant changes were: (1) increased thorax flexion; (2) reduced activity of M. erector spinae vs. increased activation of abdominals; (3) increased heart rate and Borg scores for the heaviest loads. A trend towards increased spinal flexion, reduced pelvic anteversion and rectus abdominis muscle activity was observed for the lumbar placement. The subjective scores indicate a preference for the lumbar placement. These findings suggest that carrying loads of 10% of body weight and above should be avoided, since these loads induce significant changes in electromyography, kinematics and subjective scores. Conclusions on the benefits of the thoracic placement for backpack loads could not be drawn based on the parameter set studied.     

Effect of single and double strap backpacks on lung function

Carrying heavy and moderate military loads in backpacks or as body armour compresses the chest, causing a change in lung function that is typical of a restrictive ventilatory impairment. It is not known if a lighter backpack load of only 6?kg, such as is typical of loads carried by students, will have a similar effect on lung function. There have been no studies examining whether backpacks of different strapping styles have an effect on lung function. Several designs of student backpack have recently been introduced to the market. One of the most popular is a single-strap backpack. This study examined Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV₁), FEV₁.FVC^???1% and Peak Expiratory Flow (PEF) in 13 participants (4 males, 9 females) wearing each of two 6?kg backpacks, one with two shoulder straps (a Double Strap Backpack (DSB)) and the other with a single strap (a Single Strap Backpack (SSB)) worn across the shoulder and chest. In comparison with the control of no pack (N), SSB significantly reduced FVC (by 3.94%, p?=?0.006) but there were no significant differences in FEV₁, FEV₁. FVC^???1% and PEF. The DSB also significantly reduced FVC (by 1.97%, p?=?0.034) but no significant differences were found in FEV₁, FEV₁. FVC^???1% and PEF measures. In comparison with DSB, the SSB was associated with a significantly lower FVC (by 2.05%, p?=?0.049) and FEV₁ (by 1.88%, p?=?0.029) but there were no significant changes in FEV₁. FVC^???1% and PEF. It is concluded that a backpack load of 6?kg could produce a mild restrictive type of ventilatory impairment in lung function. This effect was greater for a single cross-chest strap than for a more conventional double strap harness.     

Effect of load mass on posture, heart rate and subjective responses of recreational female hikers to prolonged load carriage

Load carriage has been associated with a risk of upper and lower limb musculoskeletal disorders with women suffering significantly higher injury rates than their male counterparts. Despite this injury risk, there are limited evidence-based guidelines for recreational hikers, particularly female recreational hikers, regarding safe backpack loads. The purpose of the present study was to determine how variations in load mass affected the heart rate, posture and subjective responses of women during prolonged walking to provide evidence for a load mass limit for female recreational hikers. Heart rate (HR), posture and ratings of perceived exertion (RPE) and discomfort were collected for 15 female experienced recreational hikers (22.3 ± 3.9 years) while they hiked for 8 km at a self-selected pace under four different load conditions (0%, 20%, 30% and 40% of body weight (BW)). Although HR was not significantly affected by load mass or walking distance, increasing load mass and distance significantly affected posture, RPE and discomfort of the upper body. Carrying a 20% BW load induced significant changes in trunk posture, RPE and reported shoulder discomfort compared to the unloaded condition. The 20% BW load also resulted in a mean RPE rating of ‘fairly light’, which increased to ‘hard’ when carrying a 40% BW load. As load carriage distance increased participants reported significantly increased shoulder, neck and upper back discomfort. Based on the changes to posture, self-reported exertion and discomfort when carrying loads of 20%, 30% and 40% BW over 8 km, it was concluded that a backpack load limit of 30% BW should be recommended for female recreational hikers during prolonged walking.     

Wearing body armour and backpack loads increase the likelihood of expiratory flow limitation and respiratory muscle fatigue during marching

Abstract

The effect of load carriage on pulmonary function was investigated during a treadmill march of increasing intensity. 24 male infantry soldiers marched on six occasions wearing either: no load, 15?kg, 30?kg, 40?kg or 50?kg. Each loaded configuration included body armour which was worn as battle-fit or loose-fit (40?kg only). FVC and FEV₁ were reduced by 6 to 15% with load. Maximal mouth pressures were reduced post load carriage by up to 11% (inspiratory) and 17% (expiratory). Increased ventilatory demands associated with carrying increased mass were met by increases in breathing frequency (from 3 to 26 breaths·min^?1) with minimal changes to tidal volume. 72% of participants experienced expiratory flow limitation whilst wearing the heaviest load. Loosening the armour had minimal effects on pulmonary function. It was concluded that as mass and exercise intensity are increased, the degree of expiratory flow limitation also increases.

Practitioner Summary: This study investigated the effect of soldier load carriage on pulmonary function, to inform the trade-off between protection and burden. Load carriage caused an inefficient breathing pattern, respiratory muscle fatigue and expiratory flow limitation during marching. These effects were exacerbated by increases in mass carried and march intensity.     

Protocols used to determine the influence of backpack load on physiological variables. Systematic review

Professional mountain rescue mountain groups use backpack equipment in their professional activities. The velocity of ambulation, gradient, load and the participant's physical characteristics have been described in the scientific literature as influential factors on response to exercise. The purpose of the present systematic review is to assess the protocols used to investigate the effects of backpacks and their influence on physiological responses at laboratory. A total of 14 articles were included in the review. Most research studies indicated participants were not experienced with backpack carriage. We observed a certain threshold on physiological changes in response to exercise was between 20 and 40 kg of backpack load. In conclusion, there is a heterogeneity of protocols used at the laboratory, hampering the comparison between different results. Future research should focus on the design of protocols that reproduce real scenarios of targeted populations.Relevane to industryRescue groups, firefighters and military personnel carry load with backpack in emergency interventions. This review analyzes different types of methodological protocols that investigate the influence of backpack load on physiological responses during exercise. The result will help manufacturer design backpacks considering the physiological burden of backpack carriage.     

Effects of backpack and double pack loads on postural stability

Measurement of postural stability is crucial for identifying predictors of performance, determining the efficacy of physical training and rehabilitation techniques and evaluating and preventing injuries, particularly for heavy load carriage in hikers, mountain search and rescue personnel and soldiers. This study investigated the effect of load distribution on postural stability in an upright stance using backpack and double pack loads under conflicting or impaired somatosensory, visual and vestibular conditions. The sensory organisation tests were conducted on 20 young adults before and after a 10-min level walking exercise. Young adults’ ability to use inputs from somatosensory and visual systems to maintain postural stability was significantly reduced following a 10-min walking exercise with a heavy backpack (30% of body weight), whereas no significant changes were observed for double pack carriage. Thus, the distribution of heavy loads to the front and back provides superior balance control compared with back-only loading.

Practitioner summary: This study investigated the effects of heavy (30% of body weight) load distribution on postural stability after a 10-min walking exercise. Backpack carriage significantly reduced postural stability, whereas there was no significant effect under double pack loads. Distribution of heavy loads on the front-and-back is desirable for superior balance control.     

Effects of load carriage, load position, and walking speed on energy cost of walking

PURPOSE: The purpose of this study was to examine the effects of load, load position, and walking speed on the energy cost of walking per unit distance (Cw: ml/kg/m). METHODS: Eight young male subjects walked on a treadmill at various speeds with and without load in the hands, on the back, and on the legs. The Cw values were determined from the ratio of 2-min steady-state oxygen consumption (Vo2) above resting value (net Vo2) to the walking speed (v): Cw = net Vo2/v. RESULTS: An energy-saving phenomenon was observed when the load was carried on the back at slower speeds. This phenomenon diminished at faster speeds, particularly when walking faster than 90 m/min. It was also observed when the load was carried in the hands at slower speeds. CONCLUSIONS: These findings partly supported our hypothesis that an energy-saving phenomenon would be observed due to an interaction between rotative torque around the center of body mass and excessive burden on the lower muscles as a function of speed.     

Effects of backpack load on critical changes of trunk muscle activation and lumbar spine loading during walking

This study investigated the effects of carrying a backpack while walking. Critical changes featuring the disproportionality of increases in trunk muscle activation and lumbar joint loading between light and heavy backpack carriage weight may reveal the load-bearing strategy (LBS) of the lumbar spine. This was investigated using an integrated system equipped with a motion analysis, a force platform and a wireless surface electromyography (EMG) system to measure the trunk muscle EMG amplitudes and lumbar joint component forces. A predictive goal programming model was developed to determine the most critical changes in trunk muscle activation and lumbar joint loading. Results suggested that lightweight backpack carriage at approximately 3% of body weight (BW) might reduce the peak lumbosacral compression force by 3% during walking compared with no load condition. The most critical changes in both trunk muscle activation and lumbosacral joint loading were found at a backpack load of 10% of BW.

Practitioner Summary: This study investigated the effects of backpack load on the LBS of lumbar spine while walking. A backpack load of 3% of BW might reduce the peak lumbosacral compression force by 3 and 10% of BW induced the most critical changes in LBS of lumbar spine.     

The effect of load distribution within military load carriage systems on the kinetics of human gait

Military personnel carry their equipment in load carriage systems (LCS) which consists of webbing and a Bergen (aka backpack). In scientific terms it is most efficient to carry load as close to the body's centre of mass (CoM) as possible, this has been shown extensively with physiological studies. However, less is known regarding the kinetic effects of load distribution. Twelve experienced load carriers carried four different loads (8, 16, 24 and 32 kg) in three LCS (backpack, standard and AirMesh). The three LCS represented a gradual shift to a more even load distribution around the CoM. Results from the study suggest that shifting the CoM posteriorly by carrying load solely in a backpack significantly reduced the force produced at toe-off, whilst also decreasing stance time at the heavier loads. Conversely, distributing load evenly on the trunk significantly decreased the maximum braking force by 10%. No other interactions between LCS and kinetic parameters were observed. Despite this important findings were established, in particular the effect of heavy load carriage on maximum braking force. Although the total load carried is the major cause of changes to gait patterns, the scientific testing of, and development of, future LCS can modify these risks.     

Effects of natural posture imbalance on posture deviation caused by load carriage

PurposeThe purpose of this study was to explore posture deviation variability caused by load carriages depending on natural posture imbalance to provide information about a carrying habit exaggerating an individual's posture imbalance. All people exhibit some imbalance from the standard anatomical pose which assumes alignment with the frontal and median planes. In this study natural posture imbalance is the starting point for determining posture deviation which is posture imbalance resulting from an activity, carrying an item.MethodsSeventeen female participants, 19–37 years old, were recruited from university staff, faculty members, and students. Participants were each scanned wearing their own underwear (bra and panties) in: (a) the anatomical pose (P1) face forward and feet placed at shoulder width without carrying an item, (b) carrying a backpack (P2), (c) carrying a shoulder bag on the right shoulder (P3R) and the left shoulder (P3L), (d) carrying a bag cross-body with a strap placed on the left shoulder to place the weight at the hip level on the right side (P4R) and the strap and handbag placed in the opposite direction (P4L), and (e) carrying a bag with the right hand (P5R) and the left hand (P5L). The bag weight was approximately 10% of a participant's body weight. Five body angles were obtained in each scanning position (eight positions total) for all participants and statistical analyses were conducted for posture assessment. Three statistical test methods were used: (a) Paired t-test to determine posture changes in each loaded position compared to natural posture in P1. (b) Paired t-test to identify differences of the degree of posture changes between right-side load (R) and left-side load (L) positions to determine a posture deviation tendency with asymmetrical load carriages. (c) Bivariate (Pearson) correlation test to examine how natural posture imbalance and posture deviation co-vary.Results(a) Asymmetrical load positions exhibited greater changes on shoulder and spine posture than a symmetrical load position, exhibiting obvious changes in P3 and P4 rather than P5. (b) The degrees and directions of posture deviation resulting from an asymmetrical load carriage varied depending on those of an individual's natural posture imbalance. When a participant exhibited great posture imbalance in P1, significant differences of posture deviation on the shoulder and spine between R and L positions were observed in P3 and P4. (c) Significant correlations between natural posture imbalance and posture deviation resulting from load carriages were found for most body angles.ConclusionsPeople need to be aware of their natural posture imbalance and try to avoid carrying heavy handbags or any type of carriages making their posture imbalance worse to prevent possible further distortion.Relevance to IndustryAlthough this study used handbags and a backpack as the load carrying devices, the way a person carries a load of any type is relevant in many industries and in the military.     

Effects of backpack weight on the performance of basic short-term/working memory tasks during flat-surface standing

This study empirically investigated the effects of backpack weight on the performance of three basic short-term/working memory (STM/WM) tasks during flat-surface standing. Four levels of backpack weight were considered: 0, 15, 25 and 40% of the body weight. The three STM/WM tasks were the Corsi block, digit span and 3-back tasks, corresponding to the visuo-spatial sketchpad, phonological loop and central executive of WM, respectively. Thirty participants conducted the STM/WM tasks while standing with loaded backpack. Major study findings were that (1) increased backpack weight adversely affected the scores of all three STM/WM tasks; and, (2) the adverse effect of backpack weight was less pronounced for the phonological loop STM task than the other STM/WM tasks. The study findings may help understand and predict the impacts of body-worn equipment weight on the worker’s mental task performance for various work activities requiring simultaneous performance of mental and physical tasks.

Practitioner summary: The current study empirically examined the effects of backpack weight on the performance of three basic STM/WM tasks. The study findings entail that reduces the weight of body-worn equipment can positively impact the worker’s mental task performance in addition to reducing the worker's bodily stresses.

Abbreviations: ACC: anterior cingulate cortex; AP: anterior-posterior; BW: body weight; CoP: centre of pressure; C-S: central executive working memory task and standing; DLPFC: dorsolateral prefrontal cortex; HIP: human information processing; ML: medio-lateral; PMC: premotor cortex; P-S: phonological loop short-term memory task and standing; SMA: supplementary motor area; STM: short-term memory; VLPFC: ventrolateral prefrontal cortex; V-S: visuo-spatial short-term memory task and standing; WM: working memory     

The effect of load mass and its placement on postural sway

The purpose of this study was to investigate the effects of increasing load on postural sway in two different carrying positions: backpack and waist jacket. Potential differences between males and females were additionally evaluated. 60 young college students participated in this study, and were assigned to backpack and waist jacket groups. The loads in both groups were 12, 21 and 30 kg. Stabilometry was used to assess the amount of postural sway. The medio-lateral and antero-posterior mean sway, mean velocity, medio-lateral and antero-posterior path length and sway area of the centre of pressure position were calculated.In the backpack group all analyzed sway parameters linearly increased with additional load, the differences were significant at p < 0.001. However no significant change of the analyzed parameters was found when the subjects carried additional load in the waist jacket.Our results indicate that postural sway depends on the amount of the load carried in a backpack. Additionally, the position of the load is of significant importance. Carrying weight in a backpack increases postural sway with increasing weight whereas carrying weight in a waist jacket does not influence the amount of postural sway. There are no significant differences in the response to the amount and configuration of the load between male and female subjects.     

Subjective perceptions of load carriage on the head and back in Xhosa women

The purpose of this study was to compare the subjective perceptual responses to both head-loading and back-loading in a group of Xhosa women. Thirty two women were divided into three groups based on their experience of head-loading and walked on a treadmill on two occasions, head-loading and back-loading, at a self selected walking speed for 4 min with a variety of loads until pain or discomfort caused the test to be terminated or a load of 70% body mass was successfully carried. After each workload there was a 1 min rest period during which the women indicated feelings of pain or discomfort in particular areas of the body via visual analogue scales. At the end of each test the women were asked to complete further questionnaires relating to pain and discomfort and on completion of the second test were also asked to compare the two loading conditions. Finally the women were interviewed to establish their history of load carriage and associated pain and discomfort. The data indicate that whilst back-loading was generally associated with more areas of discomfort than head-loading, the pain and discomfort in the neck associated with head-loading was the predominant factor in the termination of tests and that this was independent of head-loading experience. This early termination meant that, on average, the women could carry greater loads on their backs than on their heads. The study suggests that further work needs to be carried out to establish viable alternatives to head-loading for rural dwellers in Africa.     

Effects of Depth Perception on Performance of Simulated Materials Handling Tasks

Abstract

A series of experiments were performed using ft laboratory simulation of a fork-lift truck setting task. In general, the same effects were observed as found in an another study using fork-lift trucks except that the direction of errors was reversed, showing a reversal of movement relationships in the simulator. The visual angle between the drivers' direction of motion and his line of sight to the target had a large effect on performance times and error rates. When this angle was less than 12°, both times and errors increased sharply. Performance times at different movement amplitudes and target widths were a linear function of an Index of Difficulty except for target widths of less than 2% of the amplitude. Subject age and experience of fork-lift truck driving had a significant effect of performance. Augmentation of vision using a closed circuit television display was beneficial to performance, reducing times by 14% and errors by 52% showing that this is an economic proposition for materials handling vehicles.     

The effect of backpack load on the gait of normal adolescent girls

Concerns regarding the effects of load carriage have led to recommendations that backpacks be limited to 10?–?15% of body weight, based on significant changes in physical performance. However, gait responses to backpack loads are not entirely consistent and there is a particular lack of data regarding load-bearing gait in adolescent females. Gait patterns of 22 normal adolescent girls were recorded at backpack loads of 0, 7.5, 10.0, 12.5 and 15.0% body weight. Temporal-distance, ground reaction force and joint kinematic, moment and power parameters were analysed by repeated measures ANOVA with factors of backpack load and side (left or right).

Walking speed and cadence decreased significantly with increasing backpack load, while double support time increased. Kinematic changes were most marked at the proximal joints, with a decreased pelvic motion but a significant increase in the hip sagittal plane motion. Increased moments and power at the hip, knee and ankle showed increasing demand with backpack load. Parameters showed different responses to increasing load, and those that suggested a critical load indicated this to be approximately 10% body weight. While this may be due to a change in gait due to increased demand, further work is required to verify this and also to examine the cumulative effects of backpack load on the musculoskeletal system, which may be more appropriate in determining recommended load limits.     

Effects of military load carriage on kinematics of gait

Manual load carriage is a universal activity and an inevitable part of the daily schedule of a soldier. Indian Infantry soldiers carry loads on the waist, back, shoulders and in the hands for a marching order. There is no reported study on the effects of load on gait in this population. It is important to evaluate their kinematic responses to existing load carriage operations and to provide guidelines towards the future design of heavy military backpacks (BPs) for optimising soldiers' performance. Kinematic changes of gait parameters in healthy male infantry soldiers whilst carrying no load (NL) and military loads of 4.2–17.5 kg (6.5–27.2% body weight) were investigated. All comparisons were conducted at a self-selected speed. Soldier characteristics were: mean (SD) age 23.3 (2.6) years; height 172.0 (3.8) cm; weight 64.3 (7.4) kg. Walk trials were collected using a 3-D Motion Analysis System. Results were subjected to one-way ANOVA followed by Dunnett post hoc test. There were increases in step length, stride length, cadence and midstance with the addition of a load compared to NL. These findings were resultant of an adaptive phenomenon within the individual to counterbalance load effect along with changes in speed. Ankle and hip ranges of motion (ROM) were significant. The ankle was more dorsiflexed, the knee and hip were more flexed during foot strike and helped in absorption of the load. The trunk showed more forward leaning with the addition of a load to adjust the centre of mass of the body and BP system back to the NL condition. Significant increases in ankle and hip ROM and trunk forward inclination (≥10°) with lighter loads, such as a BP (10.7 kg), BP with rifle (14.9 kg) and BP with a light machine gun (17.5 kg), may cause joint injuries. It is concluded that the existing BP needs design improvisation specifically for use in low intensity conflict environments.

Statement of Relevance:The present study evaluates spatial, temporal and angular changes at trunk and limb joints during military load carriage of relatively lighter magnitude. Studies on similar aspects on the specific population are limited. These data can be used for optimising load carriage and designing ensembles, especially a heavy BP, for military operations.