Commonly, M. PhD. 2004). Keeping in mind

Commonly, backpacks are considered to be thefundamental medium of load carrying      equipments (Ismalia 2017) and this form of load carriage differs personto person based on the purpose they are carrying for. Students from differentage groups use backpack for carrying books, notebooks, other stationeries and evenlaptop while hikers use backpacks for carrying their hiking supplies liketents, fast aids, torches, water bottles etc. Variation in heaviness andduration of usage depends on the ways backpacks are used (Al-Khabbaz et. Al.2008). Carrying heavy load in the backpack hasbeen one of the primary reasons for short term and/or long term musculoskeletaldisorders for persons from different age groups.  A close relationship of different musculoskeletaldisorders with the heavy backpack carriage exists in growing school children(Shamsoddini et al.

2010). Improper and heavy carriage of backpack can leadto long term musculoskeletal disorders on neck, shoulder and back in schoolgoing children (Dolls JJ et al. 2003). Even walking for a short periodof time with backpack can significantly change the spinal curvature (Orloff andRapp, 2004). Increased loading on spinal tissue and negative effect on adolescentspinal responses are found due to inappropriate and prolonged load carriage(Grimmer et al. 2000).

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 Each year,around 13000 severe injuries are reported associated with backpacks in the USaccording to the U.S. Consumer Product Safety Commission (2015). Significant amountof researches have been done by researchers all over the world to find out thesafe weight limit to be carried. Almost all of the researchers found out ajustified weight limit between 10%-15% body weight depending onepidemiological, physiological and biomechanical approaches (Brackley, HeatherM. MSc; and Stevenson, Joan M. PhD.

2004).  Keeping in mind that number of backpack strapscan also be a contributor in instigating musculoskeletal discomfort and gaitcycle, a study in young adults was conducted considering the number of straps as a factor. But it came out to be insignificantinfluencing the parameters of gate cycle, however, in both cases increased perceivedexertion was noticed (Abaraogu et al. 2016). Improper distribution in weightscauses abnormal postures from a biomechanical perspective (Gong et al.2010).

There have been a substantial amount of researches done for school goingchildren, military personnel and hikers who walk a significant amount of timecarrying their respective backpacks. But a very few researches have been donefor the young adults carrying backpacks.   In this particular study, the outcomevariables that will be analyzed for potential injury causative and performancedeterioration while walking with backpack carriage include spatio-temporalparameters, kinetics parameters, kinematics parameters and electromyography.  Carrying backpack directly affects some of thegait parameters of a person compared to walking without backpack (Cottalordaet al. 2003). But Abaraogu et al. found no significant difference ingait parameters under three test conditions (without backpack, with one starpand with two straps). However, in a recent study, Abaraogu et al.

(2017)found a significant decrease in stride time and cadence while young adults walk fast with a load up to 10% of bodyweight.  Singh et al. (2009) observedthat a lower load configuration (at L20) with 20% body weight results in areduction in gate velocity and cadence and an increase in double support time. Astudy conducted by Xingda Qu and JooChuanYeo (2011) showed a significantincrease in step width with heavy backpack carriage that suggested “risk of fallswill increase with fatigue”. Chow et al. (2007) conducted a study that showed significantdecrease in walking speed and cadence and an increase in double support time. Barbaraet al. (2008) examined no significant differences in gait parameters in schoolgoing children while walking with backpack compared to walking withoutbackapack.

 Similarly, a study conductedby Pau et al.(2015) on 218 Italian school girls aging from 6-15 with 0%, 5%,10%and 15% body weight as backpack load showed no affect on gait parameters. Hong etal. (2003) considered backpack load condition (0, 10%, 15%, and 20% of BW)and walking distance as factors to observe any alteration of gait parameters ofchildren. However, no significant difference was found on stride and othertemporal parameters.

ON the contrary, Deepti et al.(2010) found significantincreases in stride length, step length , cadence and mid-stance of Indian infantrysoldiers with loads of  6.5% to 27.2% ofbody weight compared to no load. A very unique study with suspended-loadbackpack proved to be different than the results of conventional backpacks. Basically,the motion of this type of load has an influence of gait biomechanics because ofthe push off force (Xu et al. 2009).Therefore, a lot of inconsistencies among theresults of the available studies are apparent and most of the studies wereconducted on children.

So, in this study, the gait parameters will be taken intoconsiderations as outcome variables due to backpack load carriage among youngadults.Different findings showed significant effecton ground reactions forces due to increased load carriage. Wendy et al. (2008),during her study on ten college students with backpack load of 20% body weightwhile stair descent , found significant increase of 29.

5% in vertical groundreaction force during stance phase and an increase of 15.38% duringtoe-off  phase compared to no load.  A study on military personnel with threedifferent load carriage system ( backpack, standard and AirMesh) suggest that theshifting of centre of mass of the backpack load posteriorly reduce force at toeoff as well as decrease the stance time at heavier loads significantly (Birellet al. 2010).  A significant increasein vertical ground reaction forces with increased load while conducting a studyon Indian infantry soldiers (Deepti et al. 2013). Increased absolute GRFwas found with backpack carriage by Castro et al.

(2013) but a decreasein absolute GRF was observed by De Castro et al. (2014). In addition,ground reaction force reduced with backpack carriage while normalized to totalweight (Castro et al. 2013) but remain unchanged in the experiment on Indian infantry soldiers done by Majumder et. al (2013).

Therefore, apparently someinconsistencies were observed regarding the impact of backpack carriage onground reaction forces.Quesada et. al (1996) conducted a studyon 12 military personnel walking with backpack loads of 0%, 10%, 15% and 30% ofbody weight. The knee flexion moment increased by about 82% and 151% duringstance phase at 15% and 30% of BW load, respectively.

The dorsiflexion momentat ankle, during the same phase increased by about 14% and 28% at 15% and 30%BW load, respectively. Rebecca et al.(2015) found increased knee extensorand ankle plantar flexion moment but unchanged hip extensor moment; whereas, Quesadaet. al (2010) observed increased hip extension moment with increasingbackpack carriage. On a different study increased knee and hip extension wasassociated with backpack carriage but unchanged ankle plantar flexion moment(Wang et al. 2013).   Inconsistencies among the kinematics variablessuch as joint angles of hip flexion/extension, ankle flexion/plantar flexionand knee flexion/extension have been seen on the studies conducted to the date.Backpack carriage had different effects on hip, knee and ankle on differentstages of a gait cycle.

During the gate phase, increased hip flexionangle was reported by a study (Wang et al. 2013) between the initialcontact and loading response (at heel strike), whereas no significant changewas resulted in another study on Indian infantry soldiers (Majumdaret al 2010). Studies also show irregularity in ankle dorsi flexion angle withincreased backpack carriage. Wang et.

al (2013) and Majumder et. al (2012)found no changes in the ankle dorsi flexion with increased backpack carriage.However, Kinoshita H.

(1985) observed a reduced ankle dorsi flexion. In case ofKnee flexion, Majumder et al (2010) observed no significant change in kneeflexion angle with increased load carriage. However, studies by  Wang et al (2013) and Simpson et al.(2012)showed statistically significant increase in knee flexion during walking withincreased backpack load. Different studies could not even confer to thepoint of joint angles during early to mid-stance phase of gait cycle. Increasedknee flexion angle during this phase due to backpack carriage was observed byQuesada et al.

(2000) and Simpson et al (2012), but no significant affect wasfound by Majumder et al. (2010). Increased ankle dorsi flexion wasreported by Majumdar et al.(2010) between early to mid-stance. Increased hip extension was experimentedbetween terminal to pre-swing with increased backpack carriage (Majumder et al.

2010). On the other hand Caron RR et al.(2013) reduced hip extension anglesduring treadmill walking. During this phase (terminal-preswing) of a gait cycle,Kinoshita H. (1985) a reduction in knee flexion angle, whereas, Simpson et al.found no significant effect of backpack carriage on knee flexion angle. Most ofthe studies have consistency on ankle plantar flexion during this particularphase; no significant affect was observed by increased load carriage.

An increase in trunk flexion or forwardlean angle was consistent while walking with backpack.      

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