Walking, jogging, and running are all weight-bearing
activities often recommended to improve bone health,
but the magnitude of loads (stress) (and the resulting
deformations (strain)) imparted on bones from these
activities typically ranges from 1.2 to 4.0 times body
weight depending on the speed of movement [84].
Consequently, the effects of these activities on BMD are
mixed, although there are some cross-sectional reports
that BMD at the hip, spine, and lower extremities are 5%
to 10% greater compared to nonathletic individuals [85–
88]. Progressive resistance training (PRT) (also known as
weight lifting or strength training) is one activity associated
with high compressive and bending forces that can
increase BMD as well as muscle mass, size, and strength
[89]. Indeed, cross-sectional studies of adolescent [90,91]
and adult weightlifters [92,93], bodybuilders [94] and
those engaged in recreational weight training [95,96]
have been reported to have 10% to 33% higher BMD at
both appendicular and axial sites than nonlifters. In contrast,
athletes involved in nonweight-bearing activities
that incorporate forceful muscular contractions, such
as swimming and cycling, do not have greater BMD at
clinically relevant sites; indeed hip and spine BMD has
been reported to be up to 10% lower in these athletes
compared to nonathletes