The Effect of Backpack Carriage in Different Weights and Gradients on Ground Reaction Force Parameters of 10-12 Year Old Schoolchildren’s Gait in Tehran, Iran

Document Type : Original Articles


1 Department of Biomechanics and Sports Injuries, School of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran

2 Assistant Professor, Department of Biomechanics and Sports Injuries, School of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran



Introduction: Schoolchildren have to carry their backpacks every day on routes with different characteristics and slopes. However, the knowledge available on its effects on walking biomechanics is very limited. Therefore, this study aims to evaluate the effects of backpack carriage in different weights and gradients on the kinetics of schoolchildren’s gait.Materials and Methods: 18 primary schoolchildren living in Tehran City, Iran, with age range of 10-12 years completed 7 randomized trials of walking on a treadmill (three tasks on a flat surface, including without a backpack and with backpacks with 10% and 15% of body weight load as the control group, two tasks on a 15% positive gradient, and two tasks on a 15% negative gradient). The values of the vertical ground reaction force parameters including the first force peak, second force peak, mid support force, loading rate, push-off rate, and time-to-peak (TTP) were extracted.Results: The results of analysis of variance (ANOVA) showed that the effect of gradient on the first and second peaks, loading rate, rate of push-off, and TTP of gait was significant (P ≤ 0.001), but the effect of backpack weights on the kinetics was not significantConclusion: Carrying backpacks downhill will has more impacts on the children’s motor system, so that it seemed to have a different motor control strategy. The modification of backpack carriage methods can be one of the leading strategies to reduce the negative effects of stress on the musculoskeletal system of children.


  1. Daneshmandi H, Hoseini SH. A study of backpack carriage in iranian male students. Studies in Sport Medicine 2012; 3(10): 13-32. [In Persian].
  2. Birrell SA, Haslam RA. The effect of load distribution within military load carriage systems on the kinetics of human gait. Appl Ergon 2010; 41(4): 585-90.
  3. Birrell SA, Hooper RH, Haslam RA. The effect of military load carriage on ground reaction forces. Gait Posture 2007; 26(4): 611-4.
  4. Mosaad DM, Abdel-Aziem AA. Backpack carriage effect on head posture and ground reaction forces in school children. Work 2015; 52(1): 203-9.
  5. Dames KD, Smith JD. Effects of load carriage and footwear on spatiotemporal parameters, kinematics, and metabolic cost of walking. Gait Posture 2015; 42(2): 122-6.
  6. Chow DH, Kwok ML, Au-Yang AC, Holmes AD, Cheng JC, Yao FY, et al. The effect of backpack load on the gait of normal adolescent girls. Ergonomics 2005; 48(6): 642-56.
  7. Cottalorda J, Rahmani A, Diop M, Gautheron V, Ebermeyer E, Belli A. Influence of school bag carrying on gait kinetics. J Pediatr Orthop B 2003; 12(6): 357-64.
  8. Kellis E, Arampatzi F. Effects of sex and mode of carrying schoolbags on ground reaction forces and temporal characteristics of gait. J Pediatr Orthop B 2009; 18(5): 275-82.
  9. Kinoshita H. Effects of different loads and carrying systems on selected biomechanical parameters describing walking gait. Ergonomics 1985; 28(9): 1347-62.
  10. Liew B, Morris S, Netto K. The effect of backpack carriage on the biomechanics of walking: A systematic review and preliminary meta-analysis. J Appl Biomech 2016; 32(6): 614-29.
  11. Beurskens R, Muehlbauer T, Grabow L, Kliegl R, Granacher U. Effects of backpack carriage on dual-task performance in children during standing and walking. J Mot Behav 2016; 48(6): 500-8.
  12. Singh T, Koh M. Effects of backpack load position on spatiotemporal parameters and trunk forward lean. Gait Posture 2009; 29(1): 49-53.
  13. Orantes-Gonzalez E, Heredia-Jimenez J, Beneck GJ. Children require less gait kinematic adaptations to pull a trolley than to carry a backpack. Gait Posture 2017; 52: 189-93.
  14. Connolly BH, Cook B, Hunter S, Laughter M, Mills A, Nordtvedt N, et al. Effects of backpack carriage on gait parameters in children. Pediatr Phys Ther 2008; 20(4): 347-55.
  15. Leroux A, Fung J, Barbeau H. Postural adaptation to walking on inclined surfaces: I. Normal strategies. Gait Posture 2002; 15(1): 64-74.
  16. McIntosh AS, Beatty KT, Dwan LN, Vickers DR. Gait dynamics on an inclined walkway. J Biomech 2006; 39(13): 2491-502.
  17. Kuster M, Sakurai S, Wood GA. Kinematic and kinetic comparison of downhill and level walking. Clin Biomech (Bristol, Avon) 1995; 10(2): 79-84.
  18. Lay AN, Hass CJ, Gregor RJ. The effects of sloped surfaces on locomotion: A kinematic and kinetic analysis. J Biomech 2006; 39(9): 1621-8.
  19. Franz JR, Lyddon NE, Kram R. Mechanical work performed by the individual legs during uphill and downhill walking. J Biomech 2012; 45(2): 257-62.
  20. Tulchin K, Orendurff M, Karol L. The effects of surface slope on multi-segment foot kinematics in healthy adults. Gait Posture 2010; 32(4): 446-50.
  21. Hong SW, Leu TH, Li JD, Wang TM, Ho WP, Lu TW. Influence of inclination angles on intra- and inter-limb load-sharing during uphill walking. Gait Posture 2014; 39(1): 29-34.
  22. Lee J, Yoon YJ, Shin CS. The effect of backpack load carriage on the kinetics and kinematics of ankle and knee joints during uphill walking. J Appl Biomech 2017; 33(6): 397-405.
  23. da Rosa RG, Gomenuka NA, Oliveira HB, Peyre-Tartaruga LA. Inclined weight-loaded walking at different speeds: pelvis-shoulder coordination, trunk movements and cost of transport. J Mot Behav 2018; 50(1): 73-9.
  24. Hinde K, Lloyd R, Low C, Cooke C. The effect of temperature, gradient, and load carriage on oxygen consumption, posture, and gait characteristics. Eur J Appl Physiol 2017; 117(3): 417-30.
  25. Brackley HM, Stevenson JM. Are children's backpack weight limits enough? A critical review of the relevant literature. Spine (Phila Pa 1976) 2004; 29(19): 2184-90.
  26. Abdullah AM, McDonald R, Jaberzadeh S. The effectsof backpack load and placement on postural deviation in healthy students: A systematic review. Int J Eng Res Appl 2012; 2(6): 466-81.
  27. Janakiraman B, Ravichandran H, Demeke S, Fasika S. Reported influences of backpack loads on postural deviation among school children: A systematic review. J Educ Health Promot 2017; 6: 41.
  28. Stansfield BW, Hillman SJ, Hazlewood ME, Lawson AM, Mann AM, Loudon IR, et al. Normalisation of gait data in children. Gait Posture 2003; 17(1): 81-7.
  29. Dahl KD, Wang H, Popp JK, Dickin DC. Load distribution and postural changes in young adults when wearing a traditional backpack versus the BackTpack. Gait Posture 2016; 45: 90-6.
  30. Sinitski EH, Herbert-Copley AG, Lemaire ED, Doyle SS, Besemann M, Dudek NL. Center of pressure and total force analyses for amputees walking with a backpack load over four surfaces. Appl Ergon 2016; 52: 169-76.