Osteogenic Quantification, Autoregulation and Reliability of the Modified Push Up Drop Exercise in Premenopausal Women

Background: While lower body exercises have been well quantified for bone health programs, upper body exercises lack quantification. Purpose: This study aimed to quantify and assess the reliability of a modified push up drop exercise at different rates of perceived exertion (RPE) in premenopausal women. Methods: Twenty-two women (Mean ± SD: 33.1 ±10.0 years; 64.6 ±9.2kg; 163.8 ±5.9cm) performed modified push up drops on VALD ForceDecks at RPEs of 4, 7, and 10. To assess between-session reliability, testing was repeated 3-days later. Results: The modified push up drop exceeded the previously determined osteogenic rate of force threshold (43BW·s-1) in all RPE conditions (101.7 to 225.7BW·s-1), but only the RPE 10 condition (2.81BW’s) approached the previously determined magnitude of force threshold (3BW’s). Significant main effects (p<0.001) were observed for peak vertical force and peak rate of force development across the RPE conditions. Within-session reliability was moderate to good (ICC 0.5 to 0.76) for all RPE conditions, except for RPE 10, which showed excellent reliability for peak vertical force (ICC 0.9). Between-session reliability was poor (ICC -0.37 to 0.38) for all RPE conditions, except for RPE 4, which showed moderate reliability for peak vertical force (ICC 0.46 and 0.55). Conclusions: The modified push up drop exercise meets osteogenic thresholds necessary for bone growth in premenopausal women and can be reliably autoregulated within sessions. Longitudinal studies are needed to establish upper body thresholds associated with bone remodelling.