Dose Response Effect of Drop Jumps on Bone Characteristics

There are few studies that attempt to identify optimal exercises for bone health with specific loading variables being quantified. The identification of an osteogenic threshold during single or multiple activity bouts would allow us to understand the optimal volume/magnitude of exercise/loading that causes an osteogenic response. Understanding the optimal exercise characteristics for osteogenesis will subsequently allow specific bone enhancing exercise to be prescribed. Currently, ambiguity exists as in the guidance for optimising bone health through exercise, for example, a recently published position statement on increasing peak bone mass in adolescents recommends that 5-6 months of vigorous physical activity should be performed but does not quantify the specific speed or intensity of activity required.

pQCT and DXA will be used to measure bone characteristics. Both methods are a common way of obtaining data detailing bone architecture and geometry within established research establishments including universities and National Health Service (NHS) trusts. Through pQCT, bone geometry, both cortical and trabecular bone can be measured and as a result, bone quality can be assessed. Bone measurement via pQCT is widely used in research and is a non-invasive method of imaging bone to provide estimates of bone strength in the peripheral skeleton to differentiate cortical from trabecular bone and assess bone geometry and density. DXA is the gold standard method of measuring bone mineral density and is commonly used to assess osteoporosis risk.

In addition, body composition (which will be derived from the DXA) may be associated with bone characteristics due to body mass and composition relating to bone loading and muscle acting on bone to produce bone strain.

Inclusion criteria

• 18 to 25 years old
• Have a low physical activity status defined as partaking in physical training activities no more than 2x per week.
• No current regular participation (more than once per week) in exercise programmes known to influence bone inc. gymnastics, dance, court sports, ball sports or racquet sports.
• Be able to travel to the laboratory using a vehicle or public transport
• Have the ability to comprehend and understand communication and instruction in English in order to consent and safely participate in study.
• Have no current unresolved cardiovascular complaints to avoid any cardiovascular complications when performing activities of daily living.

Exclusion criteria

• Prescribed medication that influences bone metabolism such as corticosteroids, anticancer drugs, and diabetes related Drugs
• Joint replacement or prostheses
• Currently or recently injured
• Medical conditions adversely affected by exposure to ionising radiation.
• History of high levels of ionising radiation exposure (e.g., medical treatment).
• Breastfeeding women, pregnant women and women trying to become pregnant
• Females who are on any form of contraception that may influence changes in bone
• Females who have current or previous history of an endocrine disorder