Study: regular exercise lowers oestrogen levels in postmenopausal women

A study on postmenopausal women has offered us some information regarding how our bodies process oestrogen, with exercise proving to lower oestrogen levels. This could be why regular exercise seems to lower breast cancer risk. The study was undertaken across a year examining the differences in women who exercised regularly and those who only stretched.

The study participants

  • Overweight/obese at the start of the trial
  • Sedentary
  • Postmenopausal
  • Women

The results of the postmenopausal-oestrogen exercise study

Within three months of starting to do exercise five days per week, serum oestrogen levels dropped significantly.

After a year of regular exercise, women who decreased body fat by over two per cent also had:

  • Reduction of 16.7 per cent free serum oestradiol
  • Reduction of 13.7 per cent serum oestradiol
  • Reduction of 11.9 per cent in serum oestrone (weaker form of oestrogen than oestradiol)
  • Increase in sex hormone binding globulin (SHBG)
  • Those women on low-fat diets reduced serum levels of oestradiol by 6.2 per cent
  • Active women on no dietary limitations reduced serum levels of oestradiol by another 10 per cent
  • Those who succeeded in the exercise routine lost only about three pounds during the study, but oestradiol levels were reduced by about one-sixth compared to pre-trial levels
  • No drop in bone density was observed

Understanding oestrone, oestradiol, and SHBG

Oestradiol is more potent than oestrone, which is a different form of oestrogen. Oestrone concentrations are typically equivalent to oestradiol levels prior to menopause, but usually increase after menopause.

SHBG is a protein that binds free oestrogen, so increases in this molecule mean lower levels of available oestrogens.

The exercises

The exercise group had a moderately intense workout aimed at aerobic activity whereby the women reached 40 per cent maximal heart rate for 16 minutes per session. The workload increased gradually up to 60-75 per cent maximal heart rate for 45 minutes per session.

Treadmills, stationary bicycles or outdoor walking were used for an average of 171 minutes of exercise per week in five sessions. These results have been repeated many times, with exercise proving to be a great way to ditch some of the oestrogens that can cause problems later in life.