Article Text

Download PDFPDF
Sex differences in force attenuation: a clinical assessment of single-leg hop performance on a portable force plate
  1. A D Harrison1,2,
  2. K R Ford1,
  3. G D Myer1,
  4. T E Hewett1,3
  1. 1Division of Occupational and Physical Therapy, The Sports Medicine Biodynamics Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
  2. 2Department of Health Sciences, College of Mount Saint Joseph, Cincinnati, Ohio, USA
  3. 3Departments of Pediatrics and Orthopaedic Surgery, College of Medicine and Department of Biomedical Engineering, College of Engineering, University of Cincinnati, Cincinnati, Ohio, USA
  1. Correspondence to T E Hewett, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC 10001, Cincinnati, OH 45229-3039, USA; tim.hewett{at}


Objective Impaired biomechanics and neuromuscular control have been suggested as probable links to female sex bias in the onset of patellofemoral pain syndrome. There are limited objective, clinical measures for assessment of impaired biomechanics and neuromuscular control. The primary objective of this investigation was to examine sex differences in vertical ground reaction force (vGRF) and force loading rate in young athletes performing maximum, repeated vertical single-leg hops (RVSHs). The authors hypothesised that females would demonstrate greater vGRF and force loading rate than males and show interlimb differences in force attenuation.

Design Cross-sectional study.

Setting Paediatric sports medicine clinic.

Participants 109 Healthy high school, soccer and basketball athletes.

Assessment of risk factors Participants performed RVSHs for 15 seconds on a portable force plate with a sampling rate of 400 Hz (Accupower; AMTI, Watertown, Massachusetts, USA).

Main outcome measurements Raw vGRF was filtered with a generalised cross-validation spline using a 50-Hz cutoff frequency and then normalised to potential energy. Force loading rate was calculated by dividing normalised vGRF by time-to-peak force. Group means were compared using analysis of variance.

Results The females demonstrated significantly greater normalised vGRF (p<0.001) and force loading rate (p<0.001) during landing than their male counterparts. Neither sex demonstrated significant interlimb differences in force attenuation (p>0.05).

Conclusions The female athletes may have altered force attenuation capability during RVSHs as identified by increased vGRF and force loading rate compared with the male athletes. Portable force plates may be potential tools to identify altered force attenuation in clinical settings.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Funding This study was funded by the National Institutes of Health.

  • Competing interest None.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the institutional review board committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.