['Energy restriction causes bone loss, increasing stress fracture risk. The impact of exercise during energy restriction on bone and endocrine factors is examined. Exercise with energy restriction did not influence endocrine factors, but did mitigate some bone loss seen with energy restriction in sedentary rats.', 'Chronic dietary energy restriction (ER) leads to bone loss and increased fracture risk. Strictly controlled trials of long-term ER with and without vigorous exercise are required to determine whether exercise loading can counterbalance ER-induced bone loss. The aim of this current project is to elucidate the impact of exercise and ER on bone mass, estrogen status, and metabolic hormones.', 'Twenty-four virgin female Sprague-Dawley rats (n\u2009=\u20098/group) were divided into three groups-ad libitum fed\u2009+\u2009exercise (Adlib\u2009+\u2009EX), 40\xa0% energy restricted\u2009+\u2009exercise (ER\u2009+\u2009EX), and 40\xa0% energy restricted\u2009+\u2009sedentary (ER\u2009+\u2009SED). Energy availability between ER groups was equal. Treadmill running was performed 4\xa0days/week at 70\xa0% VO2max for 12\xa0weeks.', 'Fat and lean mass and areal bone mineral density (aBMD) were lower after 12\xa0weeks (p\u2009<\u20090.05) for ER\u2009+\u2009EX vs Adlib\u2009+\u2009EX, but ER\u2009+\u2009EX aBMD was higher than ER\u2009+\u2009SED (p\u2009<\u20090.0001). Serum leptin and a urinary estrogen metabolite, estrone-1-glucuronide (E1G), were lower at week 12 (p\u2009=\u20090.0002) with ER, with no impact of exercise. Serum insulin-like growth factor I (IGF-I) declined (p\u2009=\u20090.02) from baseline to week 12 in both ER groups. ER\u2009+\u2009EX exhibited higher cortical volumetric bone mineral density (vBMD) at the midshaft tibia (p\u2009=\u20090.006) vs ER\u2009+\u2009SED.'] Does exercise during energy restriction mitigate bone loss but not alterations in estrogen status or metabolic hormones?