Effects of Jumping on Growing Bones
Condition: Osteoporosis
MeSH terms: Osteoporosis
Study type: Interventional
Phase: Phase 2

Summary: 
      In this study we will investigate the effects of a high-impact exercise program involving
      jumping on bone mass (the amount of bone) of the hip and backbone in the growing skeleton. We
      will also look at the effects of gradually stopping the jumping program on bone mass in the
      growing skeleton. A high-impact exercise program may build more bone during childhood, while
      the skeleton is still growing. This may help prevent broken bones due to loss of bone mass
      later in life.

      We will recruit 200 children aged 5-10 to participate in the study. For 6 months we will
      train the children in either a jumping or stretching program. We will then gradually reduce
      the amount of exercise over 6 months. We will measure bone mass in the hip and backbone at
      the start of the study, after jumping, and 6 months after the jumping program is stopped. We
      will compare the results in the jumping and stretching groups.
    

Detailed description: 
      Osteoporotic fractures are increasing at an alarming rate in this country and result in over
      13 billion dollars in health costs annually. Peak bone mass, that is, an individual's maximum
      bone mass at the completion of skeletal acquisition, is an important determinant of fracture
      risk. Thus, maximizing peak bone mass may provide an effective strategy for preventing
      osteopenia and osteoporosis.

      Various investigators have postulated that increasing bone mass by 3-5 percent would reduce
      fracture risk by 20-30 percent. Our data in collegiate female gymnasts demonstrate hip and
      spine bone mineral density values of up to 40 percent above values in normal age-matched
      controls and elite runners, despite menstrual irregularities. Further, we have observed the
      dynamic response of bone to high-impact forces in gymnasts over the training season as bone
      increases of 2-5 percent.

      This is a randomized, controlled exercise intervention designed to evaluate the effect of
      high-impact loading as a means to increase bone mass during development. It will determine
      bone mass accrual and bone geometry at the lumbar spine and proximal femur in prepubescent
      girls and boys. Further, this study will evaluate the bone response from withdrawal of the
      stimulus over 6 months.

      We will recruit 200 pre-pubescent children during two separate years and randomly assign them
      to a jumping or a stretching group. The jumping group will perform double leg jumps and the
      stretching group will act as a control. Outcome variables include bone mineral density (BMD)
      at the spine and hip, estimated bone volumetric density at the spine, and cross-sectional
      geometry of the femoral neck and diaphysis.

      Implementing a specific bone-loading program during childhood will potentially allow the bone
      to increase both its mass and mineralization at an earlier age and therefore provide a larger
      foundation of mineralization for further growth throughout adolescence until skeletal
      maturity is reached. We expect our findings to provide a basis for the design of strategies
      to build bone during growth and thereby reduce osteoporotic fractures.
    

Intervention name(s): Exercise intervention
Intervention type(s): Procedure
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Osteoporosis; Bone fractures; Bone mass; Bone mineral density (BMD); Ossification; Biomechanics; Exercise; Diet; Spine; Middle childhood (6-11)