Question: In order to reduce the risk of injury, how many hours of equestrian experience must be accrued?
About the article "Equestrianism", section "Health issues".

Candidate passages:
Types of stunt effects.
Practical effects.
One of the most-frequently used practical stunts is stage combat.
Although contact is normally avoided, many elements of stage combat, such as sword fighting, martial arts, and acrobatics required contact between performers in order to facilitate the creation of a particular effect, such as noise or physical interaction.
Stunt performances are highly choreographed and may be rigorously rehearsed for hours, days and sometimes weeks before a performance.
Seasoned professionals will commonly treat a performance as if they have never done it before, since the risks in stunt work are high, every move and position must be correct to reduce risk of injury from accidents. 
Handling, riding, and driving horses has a number of health risks.
Riding has some inherent risks, as when mounted, the rider's head may be up to from the ground, and the horse may travel at a speed of up to .
The injuries observed range from very minor injuries to fatalities.
A recent study in Germany reported that the relative risk of injury from riding a horse, compared to riding a bicycle, was 9 times higher for adolescents and 5.6 times higher for younger children, but that riding a horse was less risky than riding a moped.
In Victoria, Australia, a search of state records found that equestrian sports had the third highest incidence of serious injury, after motor sports and power boating.
In Greece, an analysis of a national registry estimated the incidence of equestrian injury to be 21 per 100,000 person-years for farming and equestrian sports combined, and 160 times higher for horse racing personnel.
Other findings were that use of spurs may contribute to ankle fractures and dislocations, and helmets likely prevent traumatic brain injuries.
In the United States each year an estimated 30 million people ride horses, resulting in 50,000 emergency room visits (1 visit per 600 riders per year).
A survey of 679 equestrians in Oregon, Washington, and Idaho estimated that at some time in their equestrian career one in five will be seriously injured, resulting in hospitalization, surgery, or long-term disability.
Among survey respondents, novice equestrians had an incidence of any injury that was threefold over intermediates, fivefold over advanced equestrians, and nearly eightfold over professionals.
Approximately 100 hours of experience are required to achieve a substantial decline in the risk of injury.
The survey authors conclude that efforts to prevent equestrian injury should focus on novice equestrians.
Two things are required in order to compensate for an injury.
First, the brain must receive signals from the balance organs.
This means that movements must not be avoided, because movements create the signals the brain needs to compensate for the injury.
Secondly, the balance areas of the brain must be capable of change.
During the early stages of dizziness, many physicians counsel their patients to avoid quick movements and reduce their activities.
Most patients will be prescribed anti-dizziness medications such as Antivert (meclizine), Valium (diazepam), Xanax, Phenergan, or Compazine.
This is fine during the acute stages of a dizziness problem in order to reduce the dizziness symptoms that persist for hours or days even when the patient is not moving.
However, once the acute phase is past, inactivity and medications can interfere with the long-term compensation process.
Any medication that makes the brain sleepy, including all of the anti-dizziness medications, can slow down or stop the process of compensation, so they are often not appropriate for long-term use.
Most patients who fail to compensate are found to either be strictly avoiding certain movements, using anti-dizziness medications daily, or both.
Treatment includes VRT, gradual reduction, and eventual elimination of these medications. 
For regular training and practice sessions, gymnasts generally wear whatever they choose.
Some gymnastics schools have specific regulation attire; however, this is not usually the case.
Sleeveless workout leotards are greatly preferred, and are frequently paired with shorts, leggings, T-shirts, tank tops or bicycle shorts.
As in competition, gymnasts must tie their hair back.
Attire usually must fit close to the body in order to reduce risk of injury. 
Health claim #2.
"A healthy diet with adequate calcium and vitamin D may reduce the risk of osteoporosis".
In order to make the health claim "A healthy diet adequate in calcium and vitamin D, and regular physical activity, help to achieve strong bones and may reduce the risk of osteoporosis, the food must be:high or very high in calcium,may also be very high in Vitamin D,cannot have more Phosphorus than Calcium,must be limited in Alcoholand must have more than 40 kcal (unless it is a fruit or vegetable.