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71 Does an activity modification strategy for adolescents with Patellofemoral pain and Osgood-Schlatter affect sedentary time? An ancillary analysis
  1. Magnus Bye Blumenfeld1,2,
  2. Christian Lund Nørgaard Straszek1,2,
  3. Sinead Holden1,2,4,
  4. Kristian Thorborg3,
  5. Michael Skovdal Rathleff1,2
  1. 1Center for General Practice, Department of Clinical Medicine, Aalborg University, Fyrkildevej 7, Denmark
  2. 2Department of Health Science and Technology, Faculty of Medicine, Aalborg University, , Fredrik Bajers Vej 7D, Denmark
  3. 3Department of Orthopedic Surgery, Sports Orthopedic Research Center, Copenhagen, Copenhagen University Hospital, Kettegård Allé 30, Denmark
  4. 4School of Medicine, University College Dublin, Dubling 4, Ireland


Introduction Two clinical trials tested a new management strategy for adolescents with Patellofemoral Pain (PFP) and Osgood-Schlatter Disease (OSD). The strategy consisted of activity modification (a 4-week break from sport followed by progressive return to sport), education, and exercises. This strategy appeared to improve self-reported symptoms and reduce vigorous physical activity, but it is unclear if this had detrimental effects on adolescents’ sedentary behavior. The aim of this study was to investigate the changes in sedentary behavior during an activity modification management strategy for PFP and OSD.

Materials and Methods This ancillary analysis included data from two single arm trials of activity modification, education, and exercises of 177 adolescents’ with PFP or OSD. ActiGraph GT3X+ measured physical activity and sedentary time before and during the trial (at four weeks follow-up) when adolescents were instructed to modify sports participation. Data was only included if they had a valid week which consisted of at least 4 days with 10 hours of wear-time. Time spent in consecutive sedentary bouts of ≥10 minutes was used to calculate the average daily sedentary time.

Results Baseline sedentary time for adolescents with PFP and OSD were 344 (±74) and 349 (±39) min/day, respectively. For adolescents with PFP the mean change in sedentary time was 14 min/day (95% CI, -3 to 30min) and 8 min/day (95% CI, -7 to 24) for OSD during activity modification.

Conclusion A management strategy focusing on activity modification, education, and exercises was associated with none or only small changes in sedentary time.

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