Menstrual Irregularity, Bone Mineral Density and Rib Injuries in Current and Retired Female Lightweight Rowers

Abstract

Chest wall injury, particularly rib stress fracture, is common in female rowers. A possible role of menstrual irregularity and reduced BMD in the aetiology of rib stress fracture has been speculated but remains unclear. Recovery of menstrual function and BMD in female athletes after retiring from sport is an area lacking in research. PURPOSE: To examine the relationship between menstrual irregularity, BMD and history of rib / chest wall injury in current (CR) and retired (RT) female lightweight rowers. METHODS: 22 female lightweight rowers (CR: n=12; RT: n=10), mean (±SD) age 30.9 ±7.7 years, height 169 ±5.2cm, weight 61.4 ±3.6Kg, BMI 21.4 ±2.1Kg.m−2 volunteered to participate in this study. Their competitive levels were: International n=7, National squad trials n=6, Elite n=7, Club n=3. BMD was measured using Dual Energy X-ray Absorptiometry at the lumbar spine (LS), neck of femur (NOF), and total body (TB). Subjects completed questionnaires on medical history, training, injury and menstrual history. Results were statistically analysed using t-tests. RESULTS: 73% (CR: n=10, RT: n=6) of subjects reported a history of oligo/ amenorrhea (0-9 menses per year). Their BMD at all sites was within the normal range (WHO criteria), but they had significantly lower LS (−15.4%, p=0.0002) and TB (−4.9%, p=0.03) BMD than those with no history of menstrual problems. Retired rowers had recovery of menses but their BMD remained significantly lower in the LS (−22.6%, p=0.0002) and TB (−9.2%, p=0.004) than those with no history of menstrual irregularity. No subjects had radiographic confirmation of rib stress fracture but subjects with history of rib / chest wall injury (n = 7, 32%) had significantly lower TB BMD (−5%, p=0.02) than those with no history of rib / chest wall injury. CONCLUSIONS:Oligo/amenorrhea was common in female lightweight rowers and was associated with significant reduction in TB and LS BMD compared to eumenorrheic lightweight rowers. Retired rowers had resumption of menses but BMD remained low compared with eumenorrheic rowers, suggesting that the effects of menstrual irregularity on BMD may be irreversible. Rib / chest wall injury was associated with reduction in TB BMD, suggesting a possible role for menstrual irregularity and reduced BMD in the aetiology of rib / chest wall injuries in female lightweight rowers.