Are Athletes Seeing Red-S?

IN THE FIRST OF A TWO-PART SERIES, JESSICA PIASECKI SHEDS LIGHT ON THE FEMALE ATHLETE TRIAD – BONE LOSS, DISORDERED EATING AND AMENORRHEA

RECENTLY there has been extensive media coverage of female athletes’ menstrual cycles and the new term RED-S (Relative Energy Deficiency in Sport). However, there seems to be some confusion as to the correct term – has RED-S replaced triad? And why is the menstrual cycle impacting the physiological processes so much?

Monthly cycles

THE monthly menstrual cycle is a natural process for females and is essential to maintain bone health and fertility. It can start from the age of 12 and continue until the onset of menopause around the age of 49-52.

During the 28-day-cycle the hormones oestrogen, follicle stimulating hormone, luteinizing hormone and progesterone fluctuate at different time points. Without oestrogen, more bone would be broken down (resorption) opposed to new bone forming.

This makes the menstrual cycle an essential tool in maintaining bone structure.

The constant turnover of bone is controlled by two types of cells – osteoblasts and osteoclasts (Fig 1). Osteoblasts are involved in bone formation and osteoclasts are involved i bone resorption. Balance between these two cells is vital to maintain a steady state of bone health.

Bone resorption occurs at a much higher rate than formation – the former takes just 30 days whereas the bone remodelling cycle takes four months. Therefore, a slight imbalance can lead very quickly to a bone fracture.

Bone also responds to physical activity and impact. Mechanical strain on bone, caused by muscle forces during muscular action, activates the surface osteoblasts which begin the process of forming new bone. Continued activity causes an increase in bone mass, size and strength.