Physical Activity for Bone Health: How Much and/or How Hard?

Area of Science:

• Exercise physiology and bone health research.
• Longitudinal studies on adolescent and young adult development.

Background:

• Physical activity's role in bone health is established, with high-impact activities showing significant associations.
• However, the specific contributions of activity volume and intensity, particularly lower-intensity activities, require further investigation during critical developmental periods.

Purpose of the Study:

• To determine the relative importance of physical activity volume and intensity during late adolescence for bone health at age 23.
• To provide clear interpretations of how activity patterns influence bone outcomes.

Main Methods:

• Secondary analysis of the Iowa Bone Development Study, a longitudinal cohort.
• Activity volume (average acceleration) and intensity (intensity gradient) were calculated from ActiGraph data at ages 17, 19, 21, and 23.
• Hip areal bone mineral density (aBMD), total body bone mineral content (BMC), and hip structural geometry were assessed at age 23 in 220 participants.

Main Results:

• Additive associations were found between activity volume and intensity and hip aBMD and total body BMC.
• For males, spine aBMD intensity was independently associated with bone outcomes.
• Activity volume was independently associated with hip structural geometry, irrespective of intensity.

Conclusions:

• Optimal bone health at age 23 is associated with a profile of high-intensity and high-volume physical activity during late adolescence.
• Physical activity intensity appears critical for bone mineral density and content.
• High volumes of lower-intensity activity may specifically benefit hip structural geometry.