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PLoS One. 2016 May 31;11(5):e0156353. doi: 10.1371/journal.pone.0156353. eCollection 2016.

Effect of Chronic Athletic Activity on Brown Fat in Young Women.

Author information

1
Pediatric Endocrine Unit, Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts, United States of America.
2
Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America.
3
Division of Sports Medicine, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America.
4
Department of Biostatistics, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America.
5
Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America.
6
Diabetes, Endocrinology, and Obesity Branch, NIDDK, NIH, Bethesda, Maryland, United States of America.

Abstract

BACKGROUND:

The effect of chronic exercise activity on brown adipose tissue (BAT) is not clear, with some studies showing positive and others showing negative associations. Chronic exercise is associated with increased resting energy expenditure (REE) secondary to increased lean mass and a probable increase in BAT. Many athletes are in a state of relative energy deficit suggested by lower fat mass and hypothalamic amenorrhea. States of severe energy deficit such as anorexia nervosa are associated with reduced BAT. There are no data regarding the impact of chronic exercise activity on BAT volume or activity in young women and it is unclear whether relative energy deficiency modifies the effects of exercise on BAT.

PURPOSE:

We assessed cold induced BAT volume and activity in young female athletes compared with non-athletes, and further evaluated associations of BAT with measures of REE, body composition and menstrual status.

METHODS:

The protocol was approved by our Institutional Review Board. Written informed consent was obtained from all participants prior to study initiation. This was a cross-sectional study of 24 women (16 athletes and8 non-athletes) between 18-25 years of age. Athletes were either oligo-amenorrheic (n = 8) or eumenorrheic (n = 8).We used PET/CT scans to determine cold induced BAT activity, VMAX Encore 29 metabolic cart to obtain measures of REE, and DXA for body composition.

RESULTS:

Athletes and non-athletes did not differ for age or BMI. Compared with non-athletes, athletes had lower percent body fat (p = 0.002), higher percent lean mass (p = 0.01) and trended higher in REE (p = 0.09). BAT volume and activity in athletes trended lower than in non-athletes (p = 0.06; p = 0.07, respectively). We found negative associations of BAT activity with duration of amenorrhea (r = -0.46, p = 0.02).BAT volume correlated inversely with lean mass (r = -0.46, p = 0.02), and positively with percent body fat, irisin and thyroid hormones.

CONCLUSIONS:

Our study shows a trend for lower BAT in young female athletes compared with non-athletes, and shows associations of brown fat with menstrual status and body composition. Brown fat may undergo adaptive reductions with increasing energy deficit.

PMID:
27243823
PMCID:
PMC4886995
DOI:
10.1371/journal.pone.0156353
[Indexed for MEDLINE]
Free PMC Article

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