Does Running Cause Saggy Breasts?

You might be surprised how much I have been asked this question. I know I am! Some of these women who do ask (no men have asked me yet) have unfortunately eliminated running or excessive walking from their daily routine, in fear of getting saggy breasts.

What Does the Research Say?

There is no current evidence to support the notion that running CAUSES sagging (ptosis) of the breasts. No studies have directly correlated breast sagging with running, or predicted breast sagging from running.

So, where does this presumption come from?
Most likely, it comes from the research on breast kinematics.

In Summary

Running can put excessive tension on the chest muscles, and Cooper's ligaments that help suspend the breasts. These ligaments have been found to extend or "creep" a little bit (2cm) during a short run.

As this finding might be where the saggy breast belief comes from, Cooper's ligaments only provide weak support of the breasts. The skin is actually the biggest supporter. So, thinning and decreased elasticity of the skin is the most feasible contributor to sagging breasts with age.

Breast Kinematics

Some really great research has come out regarding breast kinematics, especially as it relates to exercise-related breast pain (mastalgia) and bra design. Here are some other interesting tidbits from around the world breast kinematic research.

1. Running causes the breast to move in a figure-8 type or "butterfly" motion, across all three dimensions: up-down, side-side, front-back. Pain can then come from the breast moving out of synchrony with the body.
2. Breast size makes a difference. As breast size increases (cup size A to JJ), so does how far they move (in all directions), and how fast they move (velocity and acceleration) during bare-breasted running.
3. Your running style can make a difference. Your running style, including torso movement, can impact how and where your breasts move during a run.
4. Chest muscles (pectoralis major) and shoulder muscles (deltoid, trapezius) are less active when wearing a bra. Take the bra away, and these muscles are under more tension to respond to the increase breast movement – which is why running bare-breasted can be more painful.
5. For what it's worth, 82% of 1285 London marathon runners self-reported to wear a bra during moderate physical activity, and 91% wore one during vigorous physical activity. 71% and 86% said that wearing a bra was "essential" during moderate and vigorous physical activity, respectively.

Conclusion

Based on what we currently know, there is no evidence to support that running causes your breasts to sag. The skin is the main, natural contributor to breast support, so take care of your skin. Eat a healthy diet of whole foods (mostly plants), stay active, avoid excessive UV exposure, and don't smoke.

Breast support (i.e. sports bra) appears to be used to help prevent pain and excessive movement, and maintain breast health – especially as breast size increases. When needed, women can benefit from professional fittings.

Here is a great article on the sports bra from the experts at the University of Portsmouth.
Bouncing Breasts: The Science of the Sports Bra

References

1. Brown, N., White, J., Brasher, A., & Scurr, J. (2014). An investigation into breast support and sports bra use in female runners of the 2012 London Marathon. Journal of Sports Sciences, 32(9), 801-809.
2. Haake, S., Milligan, A., & Scurr, J. (2012). Can measures of strain and acceleration be used to predict breast discomfort during running? Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 227(3), 209-216.
3. Milligan, A., Mills, C., & Scurr, J. (2014). The effect of breast support on upper body muscle activity during 5km treadmill running. Human Movement Science, 38, 74-83.
4. Risius, D., Milligan, A., Mills, C., & Scurr, J. (2014). Multiplanar breast kinematics during different exercise modalities. European Journal of Sport Science, (ahead-of-print), 1-7.
5. Wood, L. E., White, J., Milligan, A., Ayres, B., Hedger, W., & Scurr, J. (2012). Predictors of three-dimensional breast kinematics during bare-breasted running. Medicine and Science in Sports and Exercise, 44(7), 1351-1357.