Bone mineral density and content of collegiate throwers: influence of maximum strength.
OBJECTIVE
Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.).


METHODS
Seven throwers (4 males; 3 females) who were 19.0 + or - 0.9 years had their BMD compared to an age matched control group (n = 14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs.


RESULTS
Generally, throwers had denser bones with male throwers tending to have a greater total BMD (P < or = 0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P < or = 0.05). Furthermore, total body BMD was related to PF (r = 0.68, r(2) = 0.46) and PFa (r = 0.56, r(2) = 0.31).


CONCLUSIONS
Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.
Whittington
J
J
Sports Performance Enhancement Consortium, East Tennessee State University, Johnson City, TN, USA.
Schoen
E
E
Labounty
L L
LL
Hamdy
R
R
Ramsey
M W
MW
Stone
M E
ME
Sands
W A
WA
Haff
G G
GG
Stone
M H
MH
D015502:Absorptiometry, Photon; D000704:Analysis of Variance; D015519:Bone Density / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D057185:Sedentary Behavior; D013223:Statistics as Topic; D014142:Track and Field / Q000502:physiology*; D055815:Young Adult