Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history

Kristin L. Popp, William McDermott, Julie M. Hughes, Stephanie A. Baxter, Steven D Stovitz, Moira A. Petit

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Purpose To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. Methods We recruited 32 competitive distance runners aged 18–35, with (SFX, n = 16) or without (NSFX, n = 16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm3), total (ToA) and cortical (CtA) bone areas (mm2), and estimated compressive bone strength (bone strength index; BSI, mg/mm4) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm3 and strength strain index; SSIp, mm3) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm2/N ∗ kg− 1) at all cortical sites. Results SSIp and Zp were 9–11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11–17% lower bone strength relative to mean pkZ GRFs (p < 0.05). Conclusion These findings indicate that estimated bone strength at the mid-tibia and mean pkZ GRFs are lower in runners with a history of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture.

Original languageEnglish (US)
Pages (from-to)22-28
Number of pages7
StatePublished - Jan 1 2017

Bibliographical note

Publisher Copyright:
© 2016


  • Cortical area
  • Female
  • Peripheral quantitative computed tomography (pQCT)
  • Running mechanics
  • Volumetric bone mineral density (vBMD)


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