Purpose: To investigate the effect of a six-month teacher-led osteogenic physical activity program, vs. a self-led activity program, on ultrasound measurements of bone in inactive teenage girls.
Methods: Ninety sedentary girls [mean (SD) age 16.3 (.6) years] were identified from 300 assessed for physical activity across five schools in southeast Ireland. Schools were matched and randomly assigned to a teacher-led physical activity (TLPA) program, a self-led physical activity (SLPA) program, or a control group. Broadband ultrasound attenuation (BUA), speed of sound (SOS), and os calcis stiffness index (OCSI) were measured using a portable ultrasound machine. Anthropometry, aerobic fitness, calcium intake, and physical activity were assessed, and focus groups held one month after program completion. Descriptive statistics, paired t-tests, and analysis of variance were used to analyze the data.
Results: Both intervention groups demonstrated significant improvements (p < .05) in BUA, SOS, OCSI and aerobic fitness, i.e., TLPA: +14.9%, +21.9%, + 15.9%, and +8.5%, respectively, and SLPA: +10.6%, +30.3%, + 15.6%, and +5.1%, respectively, with no change in controls. Differences between intervention groups and controls were significant for BUA and OCSI (p < .05). TLPA and SLPA groups engaged in an average of 4.5 and 3.4 hours/week of physical activity, respectively, over the intervention period. The SLPA group continued to exercise after the intervention had ceased, whereas the TLPA group did not.
Conclusions: Previously inactive teenage girls can adhere to an osteogenic activity program whether supervised or directing their own activity. Longer-term, sustainable initiatives with this age group are needed and might focus on developing personal skills for physical activity.