The overall aim of this study is to test the hypothesis that vibration exercise can induce higher than normal bone strains and strain rates than are experienced during habitual locomotor activities.

The investigators plan to study healthy young volunteers to:

1. Determine the relationship between tibial bone strain and

   • the frequency and amplitude of vibration therapy
   • a range of habitual locomotor activities;

2. Determine the transmission of vibrations during vibration therapy, in terms of

   • amplitude attenuation and phase shift of positional coordinates and accelerations at anatomic landmarks along the lower leg and other skeletal sites
   • the relationship between these and different frequencies and amplitudes of vibration therapy;

3. Determine the muscle power in the lower limb associated with various habitual locomotor activities and its relationship to the measured tibial bone strain.

The investigators subsequently hope to use the data captured in this experiment to develop a QCT-based finite element (FE) model of the human lower limb (tibia, fibula and foot). The investigators will then validate this model in relation to the characteristics (amplitude and phase shift) of the measured tibial bone strain and transmission of vibrations to the different anatomical landmarks during vibration therapy.

Inclusion Criteria:

• Male or female volunteers, ages 18 to 50 years
• Generally healthy, as determined by review of medical history and physical exam
• Ambulatory
• Willing and physically able to undergo all study procedures
• BMD (measured by DXA) at the lumbar spine and hip within ± 2 SD of the young normal range
• BMI < 30

Exclusion Criteria:

• Previous diagnosis of osteoporosis

• History of fracture of the spine, pelvis, leg or foot

• History of bone or joint disorders affecting the shoulders, spine, pelvis, legs or feet (e.g. arthritis, congenital hip dislocation, spinal spondylolisthesis)

• Ongoing conditions or diseases known to cause secondary osteoporosis

• Malabsorption syndromes (e.g. coeliac or Crohn's disease)

• Known disorders of calcium metabolism

• Known history of thyroid disease

• Osteomalacia

• Paget's disease

• Diabetes

• History of cancer within the previous 5 years

• Epilepsy

• Ongoing conditions or use of medications that may impair vision or balance

• Use of the following medications within the previous 2 years

  • Bisphosphonates
  • Fluoride (except use for oral hygiene)
  • Strontium
  • Teriparatide
  • Other bone agents (e.g. SERMs, isoflavones, HRT, calcitonin etc)
  • Steroids

• Alcohol abuse or illicit drug use

• Pregnancy or currently trying to conceive (women only)

• Inability to give informed consent

• Known hypersensitivity to the antibiotic penicillin or cephalosporins

• Known hypersensitivity to the local anaesthetic lignocaine.