Application of the predicted biomechanics approach in assessing work-related musculoskeletal discomfort among female brickfield workers in West Bengal, India.

BACKGROUND: Manual brick manufacturing units in West Bengal, India are mostly unorganized sectors employing many migrant female workers in manual material handling tasks as brick moulders and brick carriers. OBJECTIVE: The study estimated the biomechanical postural stress developed due to manual load handling, carriage and brick transportation. METHODS: Body Part Discomfort Scale was used to assess the subjective pain felt by 18 adult female brick moulders and 12 brick carriers during work. Video recordings were taken during the actual field work and the images were analyzed for two-dimensional prediction kinetics and kinematics. RESULTS: Results show that the horizontal distance of the load from the body was 59.95±3.74 cm during the initial lifting of bricks by the brick carriers and so their biomechanical trunk angle inclination was significantly detrimental. The bending moment at the lumbosacral disc was much higher during the squatting posture while initial brick lifting. Moreover, the trunk and the neck pain of the brick carriers were caused by carrying 18% of body weight load. CONCLUSIONS: The brick carriers were the more vulnerable group in terms of work-related musculoskeletal disorders. Therefore, ergonomic interventions such as relay brick carrying and pole supported balanced brick carrying, may be implemented to reduce the prevalence of pain. This study is the first of its kind that validates the extent or the prevalence of work-related musculoskeletal disorders among the female brickfield workers through approaches of predicted biomechanics.

A Temporal Study on Learning and Memory at High Altitude in Two Ethnic Groups.

Introduction: Cognitive function has been compromised during high-altitude (HA) exposure due to slowing of mental processing. Materials and Methods: A total of 20 Indian and 20 Kyrgyz soldiers were studied at 4111 m to assess cognitive function in two different ethnic groups. Paired associate learning, pattern recognition memory, spatial span (SSP), spatial working memory (SWM), choice reaction time (CRT), and simple reaction time (SRT) were evaluated at sea level and on days 3, 7, 14, and 21 of HA stay and on day 3 of deinduction. Results: All the parameters were significantly affected at HA. Indian soldiers were acclimatized by 7 days but Kyrgyz soldiers required 21 days for acclimatization. A slow impairment in SWM, CRT, and SRT was observed in Kyrgyz soldiers than in Indian soldiers and it continues throughout 21 days of HA stay, but for Indian soldiers the deterioration was maximum on day 7 and improvement in SWM, CRT, and SRT was observed on day 14 and close to baseline value on day 21. After deinduction, although Indian soldiers attained the normal value, Kyrgyz soldiers had higher value than baseline in SSP, SWM, CRT, and SRT. Conclusion: Difference in the cognitive performances of Indian and Kyrgyz soldiers may be due to the ethnogenetic diversity of these two groups.

Correction to: Effect of heavy load carriage on cardiorespiratory responses with varying gradients and modes of carriage.

.

Effect of heavy load carriage on cardiorespiratory responses with varying gradients and modes of carriage.

BACKGROUND: The present study was undertaken to determine the effect of different uphill and downhill gradients on cardiorespiratory and metabolic responses of soldiers while carrying heavy military loads in two different modes. METHODS: Eight physically fit male soldiers with a mean age 32.0 ± 2.0 years, a mean height of 169.5 ± 4.9 cm, and a mean weight of 63.8 ± 8.4 kg volunteered for this study. Each volunteer completed treadmill walking trials at a speed of 3.5 km/h while carrying no external load, 31.4 kg load in a distributed mode (existing load carriage ensembles) and compact mode (new back pack) over 5 different downhill and uphill gradients (- 5, - 10%, 0, 5, 10%) for 6 min at each gradient. During the walking trials, heart rate (HR), oxygen uptake (VO2), respiratory frequency (RF) and energy expenditure (EE) were determined by the process of breath-by-breath gas analysis using a K4b2 system. The average of the last 2 min data from each 6 min walking trial for each individual was subjected to statistical analysis. RESULTS: All parameters (HR, VO2, RF, and EE) gradually increased with the change in gradient from downhill to level to uphill. The distributed mode showed higher values compared to compact mode for all gradients, e.g., for VO2, there was a 10.7, 7.4, 5.1, 28.2 and 18.7% increase in the distributed mode across the 5 different gradients. CONCLUSION: It can be concluded from the present study that the compact mode of load carriage is more beneficial than the distributed mode in terms of cardiorespiratory responses while walking on downhill and uphill surfaces with a 31.4 kg load.

Effect of load carriage and natural terrain conditions on cognitive performance in desert environments.

BACKGROUND: Correct decision making is a critical component of cognitive performance of a soldier, which may be influenced by the load carriage and terrain conditions during their deployment in desert environment. PURPOSE: The present study was aimed to investigate the effects of loads and terrain conditions on the cognitive performance in a group of twelve healthy heat acclimatized infantry soldiers under natural desert environment. METHODS: The soldiers participated in a 10min walking trial during carrying no load and also carrying 10.7, 21.4 and 30kg at two terrain conditions viz., sandy and hard. We studied attention, memory and executive function, which are having immense functional importance in military operations. Standardized cognitive test battery was applied to the participants after carrying each magnitude of load at each terrain. Baseline cognitive performance was recorded on a separate day and was compared with the performances recorded after the load carriage trials. An attempt was made to reveal the relationship between physiological workload (relative workload) and cognitive performance at the point of completion of load carriage trials. RESULTS: Load, terrains and load×terrain interaction did not produce any significant effect (p>0.05) on the cognitive performance. Attention and relative workload were found significantly correlated at hard terrain under no load, 21.4kg and 30kg. Significant correlation was found between executive function and relative workload at hard terrain under no load. CONCLUSION: Carrying upto 30kg load for 10min at 3.5-4kmph walking speed resulted in improvement in attention at sandy terrain, decrement in memory at both sandy and hard terrains and improvement in executive function at sandy terrain.

Soldiers' load carriage performance in high mountains: a physiological study.

BACKGROUND: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined. METHODS: Twelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5 km/h and 3.5 km/h speeds during carrying no loads and three magnitudes of load (10.7 kg, 21.4kg, 30 kg) at both altitudes. Physiological parameters such as oxygen consumption, energy expenditure, heart rate, and ventilation were recorded for each breath using a gas analyzer. The rating of perceived exertion was also noted after each load carriage session. Maximal oxygen consumption (VO2max) was measured at sea level and the two high altitudes, and respective relative workloads (% of VO2max) were calculated from oxygen consumption. Repeated measure ANOVA was applied to reveal the significant effects of the independent variables. RESULTS: The participants had significant reductions in VO2max with rising altitude. Marked increases in almost all physiological parameters were observed with increasing load, altitude, and speed. The soldiers expressed heavy perceived exertion levels with higher loads at 3.5 km/h at the two high altitudes. CONCLUSIONS: Considering the physiological responses, expressions of perceived exertion and changes in relative work load at both of the high altitudes Indian soldiers are advised to walk slowly with adequate rest in between their schedules and to carry not more than 32% of their body weight.

Effect of uphill walking with varying grade and speed during load carriage on muscle activity.

Indian soldiers, while guarding the mountainous border areas, often carry loads in steep uphill gradients. This activity may predispose the risk of muscle injury. The present study aimed to examine the effects of an increasing load, speed and gradient during incremental uphill treadmill walking on different muscles. Twelve infantry soldiers walked on a treadmill at two speeds (2.5 and 4 km/h) with no load, and carrying 10.7, 17 and 21.4 kg loads at 0, 5, 10, 15, 20, 25% gradients. Electromyographic responses of erector spinae (>240%) and vastus medialis (>240%) were mostly affected, followed by soleus (>125%) and gastrocnemius medialis (>100%) at maximum speed, load and gradient combination compared to 0% gradient. Carrying 10.7 kg at 15% gradient and above was found to be highly strenuous and fatiguing with the risk of muscle injury. Uphill load carriage in slower speed is recommended for the maintenance of combat fitness of the individual at higher gradients. Practitioner Summary: The present article has evaluated the stress encountered by soldiers during load carriage at incremental uphill gradients while walking at different speeds by recording the muscular activities. Load carriage in steep uphill gradients is highly strenuous and may lead to muscle injury thus compromising the combat fitness.

Cardiorespiratory changes with compact backpack system and distributed mode of load carriage.

In Indian Army, soldiers normally carry 21.4 kg in backpack (BP), haversack, and web distributed in different parts of the body and rifle in hand. This load distribution is unequal, may involve excess energy expenditure, mostly uncomfortable, and restricts the normal movement of the hand carrying rifle. A new BP has been developed which accommodates the rifle on sides leaving the hands free. Physiological evaluation of load carriage [21.4 kg in the existing Load Carriage ensembles (LCe) and in the new BP] and without load was carried out on a group of Indian Army soldiers (n = 8) to understand the efficacy of the new BP vis-á-vis the existing one at 4.5 km/h speed at level ground and at 5% gradient on a treadmill in controlled laboratory environment. Heart rate, oxygen consumption, relative work load and energy expenditure were determined and one-way repeated measure ANOVA was applied to compare the results. All the physiological parameters showed higher responses in distributed mode in comparison to compact mode. However, the differences were not significant. The study may be carried out on a larger sample size to find out the better efficacy of compact mode of load carriage over the distributed mode.