Dual-Energy X-Ray Absorptiometry Measurements Are Sufficiently Reliable for Assessing Rib Bone Mineral Density in Rowers and Optimizing Region-Specific Analysis

Rib stress injury is a significant concern in elite rowing, disrupting training and competition. This study aimed to assess the reliability of dual-energy X-ray absorptiometry-derived bone mineral density (BMD) measurements in elite rowers across total body and rib-specific regions of interest (ROIs). It further sought to identify the most ecologically valid rib ROI for detecting sport-specific adaptations in rowers by comparing region-specific BMD patterns across sports with contracting loading patterns (collision sports and lower body endurance). The study comprised three parts: Part A assessed intrarater reliability in 35 rowers via test-retest scans 24 hr apart; Part B evaluated interrater reliability between trained technicians in 35 nonathletes; and Part C compared rib BMD patterns across 60 elite athletes of different sport types (rowing = mechanical strain, rugby = collision, and endurance track athletes = no loading). Four rib ROIs were analyzed: standard, mod-standard, supraclavicular, and subclavicular. Reliability was determined using coefficient of variation (CV%), typical error of measurement, and intraclass correlation coefficients. Rib ROIs demonstrated excellent intrarater reliability (CV%: 0.78%-2.00%; intraclass correlation coefficients: .963-.995) and minimal interrater error (CV%: 0.34%-0.50%). Cross-sectional comparisons showed that female rowers and rugby players exhibited similar rib-to-total-body BMD patterns, as did male rowers and track athletes (p > .05). Notably, rowers displayed significantly lower relative subclavicular rib BMD compared with rugby players (p < .05). Rib BMD is reliably measurable across technicians in high-performance settings. The subclavicular ROI may be best suited for monitoring rib BMD in rowers, but further investigation is required.