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Thresholds for bone loss with energy restriction change with exercise status
Author(s) -
Swift Sibyl,
Greene Elizabeth S,
De Souza Mary Jane,
Bloomfield Susan A
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.720.9
Subject(s) - cancellous bone , sed , bone mineral , medicine , endocrinology , weight loss , lean body mass , chemistry , thermogenesis , osteoporosis , body weight , surgery , adipose tissue , obesity
Dietary energy deficits leading to weight loss can induce loss of bone. We sought to elucidate whether endurance exercise can mitigate bone loss in virgin female rats subjected to graded energy deficits. After acclimation, 72 rats (5‐mo‐old) were randomized to control groups (ADLIB‐EX & ADLIB‐SED) were fed AIN‐93M ad lib. Energy restricted, exercised groups (ER20‐EX & ER40‐EX) and sedentary energy‐restricted groups (ER20‐SED & ER40‐SED) were fed modified AIN93M with 10%, 30%, 20% and 40% less energy respectively, with 100% of all other nutrients provided. Treadmill running in EX rats increased weekly energy expenditure by 10%. At wks 0 and 12, peripheral quantitative tomography scans assessed volumetric bone mineral density or bone mineral content (BMC) at the midshaft and proximal tibia (PT). DEXA scans assessed changes in body composition and total body BMC. After 12 wk only ER40‐SED rats lost body mass (‐15%), lean mass (‐4%) and total body BMC (‐6%). Fat mass in both ER‐40 groups decreased dramatically (‐68%). The cancellous bone site (PT) was selectively affected by ER, with significant declines in both 40% ER groups. Cort. BMC at mid‐tibia was unaffected by ER. In summary, 20% ER had no negative effect on bone parameters, whereas 40% ER negatively affects cancellous bone in both EX & SED animals. There appears to be a threshold for ER effects on cancellous bone, but total body BMC loss with 40% ER is prevented by exercise. Grant Funding Source Dept. of Defense #WSIXWH‐06‐1‐0479