Steph Davies, Physiotherapist
These days the message is conveyed to us loud and clear: Exercise is good for you. Weight bearing exercise, combined with a diet rich in calcium and potassium, plus a little bit of sunshine inducing vitamin D reduces the risk of osteoporosis (thinning, brittle bones). This happens because weight bearing exercise stimulates the bone-producing cells to lay down stronger, healthier bones.
But how much is too much?
Here’s the latest:
Irregular or absent periods
‘Oligomenorrhea’ (less than 6 periods a year) or ‘amenorrhea’ (completely absent periods) can sometimes occur as a direct result of high intensity training amongst competitive athletes. Research shows that up to 50% of competitive distance runners experience this, compared to 10-20% of competitive athletes and just 5% in the general sedentary population. The physiology behind why this happens is complex; but it is thought that a hormone imbalance occurs as a result of reduced calorie intake compared with calorie expenditure; resulting in a very low body fat count. However, there is no critical level across the board and it varies from individual to individual. There have been reports of elite athletes resuming menstruation when increasing their body fat percentage and reducing training.
The effects on bones
So why is it a problem? Bone density is affected by the hormone imbalances associated with oligo or amenorrhea. It can cause ‘osteopenia’ (decreased bone density that is not yet as severe as osteoporosis). There is therefore an increased risk of sustaining stress fractures – feet, shins and hips being the most common sites that affect runners. There is then also the risk of developing osteoporosis in later life, particularly after the menopause.
Eat sufficient calories for your workout
Unless you are actively trying to lose weight, make sure you eat enough high energy food to supply the high levels of training that you do.
A nutritious diet
Eat plenty of calcium-rich food e.g. dairy products, green leafy vegetables, canned fish and sesame seeds.
If in doubt, seek nutritional advice from a qualified dietician or nutritionist.
Get enough rest
Rest is required for regeneration and strengthening of muscle and bone, so recovery days are important. Try to factor in at least 1, if not 2 rest days per week.
Seek medical advice
If you have any symptoms or stress fractures it is a good idea to seek advice from a GP, preferably one with a special interest in Sports Medicine. It may be that you need a DEXA bone scan to assess your bone density.