Trunk muscle activity in different modes of carrying schoolbags

The daily load of carrying schoolbags is influenced by the mode of carriage. Electromyographic (EMG) activity from rectus abdominis and erector spinae was recorded bilaterally in five static conditions: no bag; shoulder bag; backpack; front pack; double pack. Nineteen students carried a load of 15% of their body weight. A double pack, with the load equally distributed in a front and a backpack, showed no significant differences in EMG activity compared with unloaded standing. The activity levels of erector spinae significantly decreased while carrying a backpack and increased with a shoulder bag and a front pack. Rectus abdominis revealed significantly higher EMG levels in the backpack trial. Asymmetrical activity between the right and the left part of the back muscles was clearly observed while carrying a shoulder bag with the weight at the right side of the body. The abdominal muscles revealed a slightly significant asymmetry for the shoulder bag and, surprisingly, also for the backpack. These findings suggest that the physical stresses associated with carrying book bags can be minimized by the design of a double pack. Asymmetry in muscle activity may indicate a failure of trunk stabilization and contribute to the development back pain.

[1]  M. Nordin,et al.  A 2-year prospective longitudinal study on low back pain in primary school children , 2002, European Spine Journal.

[2]  H. Kinoshita,et al.  Effects of different loads and carrying systems on selected biomechanical parameters describing walking gait. , 1985, Ergonomics.

[3]  Stefano Negrini,et al.  Backpack as a daily load for schoolchildren , 1999, The Lancet.

[4]  Susan Limon,et al.  Children at Risk: Risk Factors for Low Back Pain in the Elementary School Environment , 2004, Spine.

[5]  S. Forjuoh,et al.  Parental knowledge of school backpack weight and contents , 2003, Archives of disease in childhood.

[6]  J. Knapik,et al.  Soldier load carriage: historical, physiological, biomechanical, and medical aspects. , 2004, Military medicine.

[7]  Paul S Sung,et al.  A Possible Methodological Flaw in Comparing Dominant and Nondominant Sided Lumbar Spine Muscle Responses Without Simultaneously Considering Hand Dominance , 2004, Spine.

[8]  Stefano Negrini,et al.  Backpacks on! Schoolchildren’s Perceptions of Load, Associations With Back Pain and Factors Determining the Load , 2002, Spine.

[9]  R. Norman,et al.  Effects of load placement on back muscle activity in load carriage , 2004, European Journal of Applied Physiology and Occupational Physiology.

[10]  S J Legg,et al.  Comparison of five modes of carrying a load close to the trunk. , 1985, Ergonomics.

[11]  S J Legg.  Comparison of different methods of load carriage. , 1985, Ergonomics.

[12]  S. R. Datta,et al.  Ergonomic comparison of seven modes of carrying loads on the horizontal plane. , 1971, Ergonomics.

[13]  Joseph J. Knapik,et al.  785 Backpack Vs. Front-back Pack: Differential Effects Of Load On Walking Posture , 1994 .

[14]  J. Knapik,et al.  Symptoms during Load Carrying: Effects of Mass and Load Distribution during a 20-Km Road March , 1995, Perceptual and motor skills.

[15]  Large-Array Surface Electromyography in Low Back Pain: A Pilot Study , 2003, Spine.

[17]  Ann P. Woodhull-McNeal,et al.  Postural adjustments while standing with two types of loaded backpack , 1987 .

[18]  H. Ullum,et al.  NK cell response to physical activity: possible mechanisms of action. , 1994, Medicine and science in sports and exercise.

[19]  Sung Gyoo Park.  Medicine and Science in Sports and Exercise , 1981 .

[20]  S J Legg,et al.  The weight and use of schoolbags in New Zealand secondary schools , 2001, Ergonomics.

[21]  R. Lloyd,et al.  Kinetic changes associated with load carriage using two rucksack designs , 2000, Ergonomics.

[22]  K Grimmer,et al.  Gender-age environmental associates of adolescent low back pain. , 2000, Applied ergonomics.

[23]  S. Terver,et al.  Influence of the mode of load carriage on the static posture of the pelvic girdle and the thoracic and lumbar spine in vivo , 2001, Surgical and Radiologic Anatomy.

[24]  W. Johnson,et al.  Soldier performance and strenuous road marching: influence of load mass and load distribution. , 1997, Military medicine.

[25]  C. Richardson,et al.  Muscle fibre orientation of abdominal muscles and suggested surface EMG electrode positions. , 1998, Electromyography and clinical neurophysiology.

[26]  W. Forrest,et al.  Muscle fibre direction of longissimus, iliocostalis and multifidus: landmark-derived reference lines. , 1989, Journal of anatomy.

[27]  T. Cook,et al.  The effects of load placement on the EMG activity of the low back muscles during load carrying by men and women. , 1987, Ergonomics.

[28]  M. S. Malhotra,et al.  CARRYING OF SCHOOL BAGS BY CHILDREN , 1965 .

[29]  Ubon Pirunsan,et al.  BMC Musculoskeletal Disorders BioMed Central BMC 32002, Musculoskeletal , 2001 .

[30]  M. Rosenstein,et al.  The Effects On Gait Timing, Kinetics, And Muscle Activity Of Various Loads Carried On The Back: 774 , 1992 .

[31]  Y. T. Wang,et al.  Influence of carrying book bags on gait cycle and posture of youths. , 1997, Ergonomics.

[32]  R Lloyd,et al.  The oxygen consumption associated with unloaded walking and load carriage using two different backpack designs. , 2000, European journal of applied physiology.

[33]  C Marcelli,et al.  Nonspecific back pain in children. A search for associated factors in 14-year-old schoolchildren. , 1999, Revue du rhumatisme.