Jump-In: Building Better Bones

University of Arizona

Status: Completed

Conditions: Adolescent Development

Treatments: Other: Skeletal loading

Study type: Interventional

Funder types: Other

Identifiers

NCT00729378

HD050775

Details and patient eligibility

About

The Jump-In study will prospectively assess the effects of impact exercise on skeletal development in young girls, including bone mass, bone mineral density, and bone geometry. We hypothesize that girls who regularly participate in impact loading exercise will accrue greater skeletal mass, increase bone density and undergo structural adaptations that in combination will improve bone strength compared to girls who do not participate in impact exercise.

Full description

Jump-In is a school-based, block-randomized, trial of the effects of impact-loading exercise on skeletal development in prepubescent and early pubescent girls. Fourth (n=~200) and sixth (n=~200) grade girls in 14 Tucson (Arizona) schools with no contraindication to physical exercise will be enrolled. Girls in intervention schools will participate in impact activities 3 times per week at school, progressively increasing the number (up to 40) of jumps and their height (from 6 inches to 18 inches per repetition) over the initial 2 months. Thereafter, new activities will be introduced approximately every 2-3 months to maintain interest and motivation, and continually stress the skeleton in novel ways, over 2 years of intervention. Physical and behavioral assessments will be done in both intervention and control groups at baseline, end of the initial school year, and yearly thereafter for 5 years. Assessments include height and weight, selected skeletal lengths, fat, lean soft tissue, bone mineral content and areal density from dual energy x-ray absorptiometry (DXA), and bone geometry (e.g., cortical thickness, periosteal circumference and cortical and trabecular density) and muscle area from peripheral quantitative computed tomography (pQCT). Also, maturation will be assessed via the Tanner Stage (self-assessment against standardized drawings of stages of physical development), diet from the Harvard Youth Food Frequency Questionnaire, and physical activity using pedometers and standardized questionnaires. We hypothesize that girls in intervention schools will demonstrate enhanced skeletal development, including greater mineral mass and density, and enhanced bone geometry, leading to greater bone strength compared to girls in control schools. We further hypothesize that younger (Tanner Stage 1) girls will experience greater adaptations than older girls (Tanner 2 and 3), and that positive adaptations will be maintained throughout the 3-year follow-up period.

Enrollment: 509 patients

Sex: Female

Ages: 9 to 12 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

female; entering 4th or 6th grade at enrollment; and willing and able to undergo all of the testing requirements; no physical conditions that limit participation in physical activity/exercise; able to read and write English.

Exclusion criteria

Girls with severe learning disabilities (identified by schools), who are unable to complete questionnaires or otherwise comply with assessment protocols will be excluded. Any subjects (or potential subjects) suffering from medical conditions and/or disabilities that would limit their participation in exercise will be excluded from the study, following the American Academy of Pediatrics (AAP) guidelines. Further, any volunteers who are taking medications that would limit exercise and/or alter bone mineral accrual will also be excluded from the study. Girls with a positive pregnancy screening test at the time of the lab visit before DXA scanning will be excluded.

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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509 participants in 2 patient groups

Exercise Intervention

Experimental group

Description:

Implementation of intervention program designed to provide skeletal loading through high impact activities. All activities performed by subjects in exercise intervention arm will be assessed by physical activity questionnaire and use of pedometer. Have baseline anthropometric measurements, total body DXA scans and peripheral quantitative computed tomography (pQCT) scans of the tibia and femur.

Treatment:

Other: Skeletal loading

Control

No Intervention group

Description:

Participants in this arm will not take part in exercise intervention. All activities performed by subjects in control arm will be assessed by physical activity questionnaire and use of pedometer. Have baseline anthropometric measurements, total body DXA scans and peripheral quantitative computed tomography (pQCT) scans of the tibia and femur.