Stress Fractures and Energy Deficiency in Premenopausal Exercising Women
Open Access
- Author:
- Langue, Michael Aaron
- Area of Honors:
- Kinesiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Mary Jane De Souza, Thesis Supervisor
Jinger S. Gottschall, Thesis Honors Advisor - Keywords:
- Stress fracture
bone
premenopausal women
exercise
energy deficiency - Abstract:
- Stress fractures are a common injury among exercising women and often interrupt training and hinder athletic performance. Furthermore, the presence of a stress fracture may indicate other underlying health problems in female athletes such as an energy deficiency, menstrual disturbances, or low bone mass. An energy deficiency has been shown to impact hormone concentration and, in turn, bone health through suppressed bone formation or low bone mass. As such, the purpose of this paper is to determine whether exercising women with stress fractures have suppressed resting energy expenditure (REE) and metabolic hormones, such as total triiodothyronine (TT3) and insulin-like growth factor-1 (IGF-1). Exercising women with a lower limb stress injury (SFx) and healthy exercising controls (NSFx) were recruited. As indicators of energy status, resting energy expenditure was assessed using indirect calorimetry, and a blood sample was collected for measurement of circulating TT3 and IGF-1 concentrations. SFx (n=15) and NSFx (n=13) women aged 21.1 and 20.6 respectively, differed significantly in height and lean mass. Serum concentrations of TT3 and IGF-1 did not differ between groups. Similarly, REE and the ratio of REE/pREE were not different between the SFx and NSFx women. However, the SFx group demonstrated a trend toward a lower REE/kg LBM (p=0.083) and higher exercise volume (p=0.093) compared to the NSFx group. Assessment of exercise volume as high (cutoff) or normal (cutoff) revealed that a greater proportion of SFx women (73%) participated in a high volume of exercise compared to the NSFx women (23%). When categorizing the women based on exercise volume, the high exercise volume group (add in here the cutoff) demonstrated a higher concentration of IGF-1 (p<0.001) compared to the normal exercise volume group (add in cutoff). Energy status, as assessed by REE and circulating concentrations of IGF-1 and TT3, was unable to discriminate between exercising women with and without a lower limb bone injury. However, the high volume of exercise seen in the stress fracture group may mask the suppression of IGF-1 caused by an energy deficiency due to the stimulatory effect of exercise on IGF-1 production.