Affiliations: Simmons College, Boston, MA, USA | MSPT, BOACES, Scotia, NY, USA | MSPT, Shrewbury, MA, USA | MSPT, Mount Auburn Hospital, Cambridge, MA,
USA | MSPT, Lowell, MA, USA
Note: [] Address for correspondence: Dr. Shelley Goodgold, Graduate
Program in Physical Therapy, Simmons College, 300 The Fenway, Boston, MA 02115,
USA
Abstract: Trunk forward lean (TFL) has been identified as a postural
adaptation to increases in backpack load, and spinal forces have been presumed
based on TFL. This pilot project examined the combined effects of increasing
backpack load and task demand on TFL. Two boys with typical development, aged
11 and 9, were participants. Peak5 Motion Analysis Videography was used to
gather 2D kinematic data under three levels of backpack load (0%, levels of
task demand (stand, walk and run). Passive reflective markers were placed on
anatomical landmarks, and TFL was calculated by the angle formed by a line
joining the right acromion and right greater trochanter and a vertical
reference line. Descriptive statistics were performed to compare TFL under the
nine experimental conditions. Although TFL most often increased with increases
in backpack load and task demand, TFL was not dose dependent. Postural patterns
varied between participants, and the findings supported a ceiling effect. In
conclusion, to compensate for changes in inertia and center of gravity when
wearing a backpack, TFL represents a dynamic emergent strategy that varies
based on task demand and characteristics of the individual. Further research on
TFL is warranted, and clinicians should be cautious when recommending safe
carrying loads for children based on posture.
Keywords: posture, trunk forward lean, backpacks, school-aged children
