Ground reaction forces, bone characteristics, and tibial stress fracture in male runners
cross-sectional study, all male runners.
conflicting findings regarding GRF values between stress fracture and non-injured groups:
- Grimston et al 1991 Bone mass, external laods, and stress fractures in female runners - Grimston et al 1994 external loads throughout a 45 minute run in stress fracture and non-stress fracture runners
in military recruits: wider tibia associated with less stress fractures (citations 13 14 24 25), but no clue about athletes
low bone mineral density could theoretically contribute to stress fracture incidence (#9-11), but inconclusive (#3 5 6 13 15). Most of these studies are either in military populations or female athletes. present study looks at male athletes.
46 men age 18-42: half had a history of a healed tibial stress fracture within 5 years (mean 2yr), other half were matched based on age, height, weight, years running, weekly training volume, competitive distance, and performance (a lot of training partners of the injured).
- ran across force plate with their regular running shoes at 4.0 m/s +/- 10%
- 10 trials per leg
- measured: ** impact peak, time-to-impact, active peak, time-to-active peak, peak horiz, and time-to-peak horiz.
- also DXA scans of both legs.
- also most got CT scans in the middle third of tibia (r leg only)
- no difference between groups for peak forces or time-to-peak forces for impact, active, or horizontal.
- no difference betweeen groups for mineral content or mineral density for adjusted tibial area but if total body mass and height were covariates, then tibial none area was smaller in stress fracture group (narrower tibia).
- when body mass and height were covariates, stress fracture group had smaller total cross area.
Folks with smaller bones are at greater risk than those with big bones. Bone geometry important (ref 3 13 24 - military). Expect differences in cross-sectional area of 4.4 (milgrom et al) - 10.6 (beck et al). THis study found 8.4% difference. However, different methods of measuring will influence differences. The present study didn’t have to use radiographs.
Suggest tibia might be better to model tibia as a triangle with an elipse hole, not two elipses. Lot of variation though.
Bennell 12 month prospective study on 49 male track and field athletes also found no difference in mineral content or density between groups. In order to compare bone density between groups, you must match for body weight because it’s a huge predictor. BUT bone mineral density seems to be a good predictor in female athletes (ref 6 and 26). Likely due to the role of female sex hormones on bone density.
- Lafortune 1991: Three dimensional acceleration of the tibia during walking and running.
- Grimston et al 1991 Bone mass, external laods, and stress fractures in female runners
- Grimston et al 1994 external loads throughout a 45 minute run in stress fracture and non-stress fracture runners
- Scott & Winter 1990 internal forces at chronic running injury sites