Aromatase inhibitors help women react better to strength training


Women who have survived breast cancer and use aromatase inhibitors react surprisingly well to strength training. Researchers at Oregon Health and Science University discovered that the use of aromatase inhibitors can speed up the formation of new muscle mass in cancer survivors.

Cancer & the body
Women who survive breast cancer often pay a high price. Chemotherapy destroys the cancer but reduces bone and muscle mass – to say nothing of other side effects. Breast cancer survivors often become less active and as a result put on weight. The researchers wanted to know whether strength training could help fight the side effects.

The researchers used a training programme that they had developed to help fight osteoporosis in healthy women. The women trained their legs with wall sits, squats, deadlifts, and forward and sideward lunges. In addition the women trained their upper bodies with exercise machines including the row, chest press, lateral raise and push up machines. The researchers combined the strength training with plyometrics and got the women to jump wearing a weighted vest.

A workout consisted of 6 sets of jumps, 10 reps each, 2 sets of exercises for the upper body and 3-4 sets of exercises for the lower body. The women trained twice a week.
A control group did stretching exercises twice a week. [FLEX]

After a year the researchers concluded that the strength training [POWER] had stopped bone tissue degeneration [BMD] in the vertebrae [Lumbar spine] and the hip [Total hip].

In the strength-training group the bone-free lean mass had increased by 1.38 percent. The increase for the stretch group was 1.12 percent. The difference between those groups was not statistically significant. But this picture changed when the researchers also looked at the use of aromatase inhibitors and put together the figure shown above. Then they noticed that women who used aromatase inhibitors and trained with weights did build up significantly more bone-free lean mass.


“In our study, we found greater between group differences in lean body mass over 1 year among aromatase inhibitor users that suggest a potentiating influence of aromatase inhibitors on training-induced hypertrophy”, the researchers write.

“Recently, aromatase inhibitors use has been shown to increase free testosterone and lean mass in breast cancer survivors without concomitant changes in body fat. A possible synergistic effect of aromatase inhibitors and resistance training on lean mass in breast cancer survivors is an intriguing finding that is worth further study.”

Strength training stops bone loss and builds muscle in postmenopausal breast cancer survivors: a randomized, controlled trial.


Targeted exercise training could reduce risk factors for fracture and obesity-related diseases that increase from breast cancer treatment, but has not been sufficiently tested. We hypothesized that progressive, moderate-intensity resistance + impact training would increase or maintain hip and spine bone mass, lean mass and fat mass and reduce bone turnover compared to controls who participated in a low-intensity, non-weight bearing stretching program. We conducted a randomized, controlled trial in 106 women with early stage breast cancer who were >1 year post-radiation and/or chemotherapy, ? 50 years of age at diagnosis and postmenopausal, free from osteoporosis and medications for bone loss, resistance and impact exercise naïve, and cleared to exercise by a physician. Women were randomly assigned to participate in 1 year of thrice-weekly progressive, moderate-intensity resistance + impact (jump) exercise or in a similar frequency and length control program of progressive, low-intensity stretching. Primary endpoints were bone mineral density (BMD; g/cm²) of the hip and spine and whole body bone-free lean and fat mass (kg) determined by DXA and biomarkers of bone turnover-serum osteocalcin (ng/ml) and urinary deoxypyrodiniline cross-links (nmol/mmolCr). Women in the resistance + impact training program preserved BMD at the lumbar spine (0.47 vs. -2.13%; P = 0.001) compared to controls. The resistance + impact group had a smaller increase in osteocalcin (7.0 vs. 27%, P = 0.03) and a larger decrease in deoxypyrodinoline (-49.9 vs. -32.6%, P = 0.06) than controls. Increases in lean mass from resistance + impact training were greatest among women currently taking aromatase inhibitors compared to controls not on this therapy (P = 0.01). Our combined program of resistance + impact exercise reduced risk factors for fracture among postmenopausal breast cancer survivors (BCS) and may be particularly relevant for BCS on aromatase inhibitors (AIs) because of the additional benefit of exercise on muscle mass that could reduce falls.

PMID: 21424279 [PubMed – indexed for MEDLINE] PMCID: PMC3124708