The Best Things in Life are Free. Especially Testosterone!

You’ve heard of testosterone by now, but did you know that there is such a thing as free testosterone? Many substances in your blood are carried by proteins, and testosterone is frequently bound by a substance called Sex Hormone Binding Globulin. When testosterone is unbound from proteins, it has more biological activity to promote growth of muscles, provide energy, improve mood, and have a biological effect.

Testosterone levels tend to decline as men age, and sex hormone binding globulin tends to rise, causing a decrease in the levels of free testosterone, and reduced activity of our sex hormones.¹ This reduction in hormones is commonly called Andropause.

A Scottish study published in The Aging Male indicated that men who were previously not active in any organized exercise programs saw improvements in total testosterone levels after 6 weeks of training with walking, jogging and cycling at progressively higher intensity bursts of activity. Sex Hormone Binding Globulin (SHBG), the carrier that binds testosterone in the body, also went up.² This means that the bioavailable form of testosterone, free testosterone, was not increased due to the rise in SHBG.

So what do we make of a study like this? An important thing to remember is that total testosterone matters, but free testosterone is a more potent driver of testosterone’s ability to make you feel fantastic. One thing is certain: It is clear from numerous studies that men who exercise should see benefits in their overall testosterone levels.

We do not have complete knowledge of the role of SHBG bound testosterone yet, but we do know this bound testosterone can still leave the larger arteries in the blood stream and saturate your tissues. But what is this bound testosterone doing? We aren’t totally sure, but it doesn’t have the same pro-growth, anti-depressant, male virility effects. The important thing to consider in a study that shows Testosterone benefit is whether it is providing a boost in both free and total testosterone. Your provider should also be looking at these levels when they assess your response to hormone therapies.

A lot has been made of newer high intensity interval training (HIIT) regimens. Another Scottish study from the same group examined the testosterone and SHBG (Sex Hormone Binding Globulin) responses to training in previously sedentary men. These men participated in high intensity interval training with a warm up phase of 150 minutes of aerobic conditioning per week for 6 weeks, followed by a second phase of HIIT sessions every 5 days. The workouts consisted of 6 x 30 second sprints with 3 minutes of recovery between sprints. Total testosterone and sex hormone binding globulin increased even after the preconditioning phase, but after the high intensity phase, the free (available) testosterone levels increased in small but significant amounts in these men as well. This means that the active form of the hormone had increased after the high intensity activity.³

This information suggests that not only can interval training raise total testosterone, but it can also raise the free, active forms of the hormone. The most substantial piece of information in this study was the increase in total testosterone of 17% among the study participants after preconditioning and HIIT. This represents a significant increase and suggests that interval training could really help boost your male hormone profile.

There is one other important message from these studies to consider. Both of these studies showed clear benefits to testosterone from vigorous exercise. These men did not need to use injections or creams to increase their levels of testosterone. Testosterone prescriptions are not for everyone, and exercise may be an important addition to your lifestyle if you cannot use testosterone medicines (you should make sure you check with your doctor whether exercise is safe for you). If you’re not currently exercising at least 150 minutes per week, you should start as soon as possible, provided that it’s safe.

If you’re interested in knowing about your levels of testosterone, how to improve your virility, and the natural and prescription options for boosting testosterone levels, call Full Circle Care today to learn more.


¹ Stanworth RD, Jones TH. Testosterone for the aging male; current evidence and recommended practice. Clin Interv Aging. 2008;3(1):25-44.

² Hayes L, Sculthorpe N, Herbert P, Baker J, Reed D, Kilduff L, Grace F. Testosterone in Older Men. Medicine & Science in Sports & Exercise. 2015;47:26. doi:10.1249/01.mss.0000476465.62871.19.

³ Hayes L, Herbert P, Schulthorpe N, Grace F. Exercise Training Improves Free Testosterone in Lifelong Sedentary Aging Men. Endocrine Connections 2017:EC-17-0082. doi:10.1530/ec-17-0082.


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