The Relationship between Running and Bone Health in Women
BY Siobhan Bottomley
Physiotherapist at Kings Park Medicine Centre
Female runners are twice as likely to suffer a bone stress injury than their male counterparts, why is this?
Women generally have lower bone density than men, making them more susceptible to stress fractures and other bone-related health issues. Additionally, female runners may be more prone to hormonal imbalances, such as low estrogen levels, which can further impact bone health and increase the risk of injuries.
Regular running has been shown to have positive effects on bone health in women. Weight-bearing exercises like running help to increase bone density and strength, which is important for preventing osteoporosis and reducing the risk of fractures. Bone strength is determined by a number of factors including loading, hormonal variations and nutritional sufficiency.
Mechanical loading plays an important role in maintaining bone health. Correct loading stimulates the repair and regeneration of bone. Repetitive loading activities, such as running, result in an accumulation of micro-trauma to our bones. Bone has to continuously recycle itself and form new bone in response to this loading to maintain, repair or increase bone strength. The entire adult skeleton is completely regenerated approximately every 10 years through this process.
Overloading / over-training causes an accumulation of micro-trauma faster than our body can repair it and progressively weakens our bones until they fail (fracture). Overloading is often combined with under fueling and this is the leading cause of stress fractures, one of the most prevalent running related injuries in women. It is essential that female runners maintain the structural integrity of their bones by gradually increasing their training load to provide an appropriate increase in bone strength as this can prevent exercise induced degeneration. It is suggested that the optimal loading strategy is to increase your weekly training load by a maximum of 30% of the average distance run in the last 4 weeks.
Women are much more likely to under fuel during training or partake in some kind of dietary restriction and are thus twice as likely to obtain a stress fracture when compared to men. The Female Athlete Triad (FAT) describes the impact of low energy availability acquired from restricted eating on the female reproductive system and the subsequent loss of bone mineral density in female athletes. When there is an imbalance between the energy supplied to the body and the energy expended, we create an energy deficit. During this state of energy deficit, energy supply is reserved for only the essential functions of the body, which does not include the female reproductive system. If this state of energy deficit is prolonged, we may start to see signs such as irregular menstruation or amenorrhea as the body is unable to supply the reproductive system with sufficient energy to function correctly. There is a high prevalence of this condition in women participating in endurance sports such as long-distance running.Â
Exercise alone does not negatively impact reproductive health, but when coupled with low energy availability we start to see a decrease in the level of estrogen and other important reproductive hormones being produced. Estrogen plays an important role in regulating and promoting the formation of new bone. A decrease in estrogen leads to the loss of the normal repair mechanisms for the micro-trauma we acquire in our bones as a result of exercise. Without this repair process we start to see a decrease in bone mineral density and bone strength that greatly increases the risk of bony stress fractures. It is important to note the FAT does not only affect elite female athletes but can affect recreational sports women too.
In a study conducted in 2021, 24% of recreational female runners reported having some knowledge of this condition, but only 5% could accurately describe it. The same study showed that these female runners had shorter menstrual cycles than non-runners and suggests that this is the first symptom preluding the menstrual dysfunction associated with FAT. It has been shown that up to 30% of female runners suffer from menstrual disorders and have little to no knowledge of the impact of this on their bone health. These menstrual disorders are most likely the result of dietary restrictions combined with over-training causing low energy availability.
A similar process occurs when female runners enter menopause. Menopause results in a decreased production of estrogen within the body, which directly impacts the body's ability to repair the micro-damage in our bones efficiently and can contribute to the development of osteoporosis. Osteoporosis is a condition characterized by chronic low bone mineral density that results in brittle bones that fracture easily. It is vital that female runners educate themselves on these disorders and supplement as required to prevent low bone mineral density and stress fractures.
Tips for preventing bone stress injuries
Make sure you are loading your bones correctly by gradually increasing your total weekly training distance. It is recommended that you increase your total weekly distance by no more than 30% of the average distance you've run over the last 4 weeks.
Allow for adequate rest and recovery between training sessions by incorporating rest days and making sure you get enough sleep. Remember, rest is part of training.
Ensure you are eating enough before, during and after training sessions to prevent energy deficit.
Speak to a dietitian about what supplements may be appropriate to help you reach your micro-nutrient intake and support your endocrine system.
In conclusion, female runners, with their naturally lower bone density and high prevalence of hormonal imbalances, are more susceptible to the development of bone health issues such as stress fractures and osteoporosis. Running is a great tool for supporting bone health in women if it is done correctly. However, if coupled with factors such as overloading and under fueling, symptoms of the Female Athlete Triad may develop and result in a subsequent loss of bone density and strength. With proper knowledge, awareness, and proactive measures, female runners can take steps to mitigate these risks and promote optimal health. Gradually increasing training load, prioritizing rest and recovery, maintaining a balanced diet, seeking professional guidance in nutrition and supplementation and understanding the impact of conditions like the Female Athlete Triad and menopause on bone health are crucial steps in preventing bone stress injuries and safeguarding their long-term bone health.
*For more information contact Siobhan Bottomley at:
Kings Park Sports Medicine Centre
892 Umgeni Road, Morningside Durban
031 303 3874
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