Senior cricket fast bowlers (FB) have high lumbar spine bone mineral, particularly on the contralateral side to their bowling arm. It is thought that bone possesses its greatest ability to adapt to loading during adolescence but is unknown at what age asymmetry develops in FB and how adaptation develops with age.
PURPOSE: To determine how lumbar bone mineral and geometrical properties differ according to age in FB.
METHODS: With NHS and institutional ethics approval, 107 elite adolescent and senior male FB aged 14 to 35 years received a single AP lumbar spine DXA scan (GE Lunar iDXA, GE Healthcare, USA). Bone mineral density (BMD) and bone mineral content (BMC) were derived for each vertebra, along with average vertebral height and width, area and Z-score (Lunar enCore v17, GE Healthcare, USA). Custom regions of interest derived the bone mineral in the lateral third of the non-dominant (ND) and dominant (D) sides of the vertebral body (respective to bowling arm). FB were split into 14-15 (n=27), 16-17 (n=28), 18-19 (n=22), 20-24 (n=16), and 25+ (n=14) age groups. ANOVAs were used to compare the age group means for each variable, with FFM as covariate.
RESULTS: Lumbar spine BMD, BMC, Z-score, area, width and height significantly differed between age groups at all vertebral levels (P<0.01), but differences in area and height were no longer significant with FFM included as a covariate (P≥0.38). Mean BMD (± SD) L1-L4 Z-scores increased progressively with age from +0.83 ± 1.24 at age 14-15 to +2.69 ± 1.17 at age 25+. BMD and BMC on the ND and D sides significantly differed with age (P≤0.04) and side (P<0.01), and by age on each side (P≤0.04) as highlighted at L3 in figure 1.
CONCLUSIONS: Adaptation to fast bowling, in terms of whole vertebra and site-specific bone mineral, substantially increases with age particularly on the ND side.