Does Weightlifting Increase Testosterone?
Written by Oliver Greenwood: BSc(Hons) Applied Sport & Exercise Science.
--
Testosterone supression can affect any man, but particularly as they age. Therefore it is important to understand whether weight training can increase natural testosterone production.
This article will cover whether weightlifting can help to naturally stimulate testosterone production.
What will testosterone do for a man?
Classically, testosterone (androgen hormone/testoid) a hormone typically associated with one’s masculinity (Patel et al., 2019).
Testosterone is a pleiotropic hormone (Patel et al., 2019), which means the hormone has multiple functions such as modifying human behaviours (Neolife, 2018) various physiological roles and has even been shown to have the capacity to improve some symptoms of depression (Neolife, 2018).
With testosterone being commonly known for its actions on muscle growth, it comes as no surprise that low levels of testosterone are linked to a loss of muscle mass (Kelly and Jones, 2015).
This shows that there is a possibility that increasing muscle mass through exercises, such as weightlifting, could be beneficial towards increasing testosterone in the body (Kelly and Jones 2015).
Hypogonadism
However, testosterone deficiency is highly common among men impairing many day-to-day bodily functions for instance insulin resistance (Kelly and Jones, 2013).
This can cause a decrease in the stimulation of glucose transport along with decreasing insulins glucoses storage (Kahn and Flier, 2000). It has also been reported that testosterone deficiency is directly related to cardiovascular disease risk factors (Kelly and Jones, 2013).
The points made above will be the key areas of discussion throughout this article. Furthermore, it will be discussed the role ageing plays on testosterone levels, along with, what are the best exercises to produce optimal testosterone levels within the body.
Benefits of Testosterone
As reported above lower levels of testosterone can cause many unwanted complications within the body, so having a higher level of natural testosterone can be beneficial.
Can a lack of the androgenic hormone cause depression?
One major benefit of higher testosterone levels is its ability to be able to fight depression. Worldwide there is an issue regarding mental health.
With depression alone affecting more than 120 million people (Lepine and Bridley, 2011). Within this around 25% of the UK’s adult residents are suffering from Mental Health Issues (MHI) (Parker and Bailey, 2018).
Research conducted by Almeida et al., (2008) reported on 203 men who completed a self-report questionnaire and a 15-item geriatric depression scale. Participants then consumed the testosterone concentration (ranged between 20 to 1602 ng/dL).
The results showed there to be a negative relationship between testosterone levels and depressive symptoms. However, this was only a weak correlation (p= -0.07) meaning more research should be conducted within this area.
Body Fat and Testosterone
Another benefit testosterone brings to the table is its ability to decrease body fat (Traish, Saad, Guay, 2009).
This is because testosterone plays a vital part in the regulation of insulin, glucose and fat metabolism. As one’s testosterone levels decrease the body’s capability to regulate insulin decreases (Kahn and Flier, 2000). T
his in turn causes a decreased rate of glucose transport along with insulins glucoses storage decreasing (Kahn and Flier, 2000), resulting in adipose tissue to begin accumulating.
The accumulation of the adipose tissue contributes to further negative actions of decreased testosterone levels (Traish, Saad, Guay, 2009). I
n a study conducted by Kalinchenko et al., (2010) 184 men had their body composition evaluated after 30 weeks after ingesting 1000mg of testosterone. The results of this testing showed an average weight loss of 4.3kg.
This is also supported by a study from Svartberg et al., (2008) who found a 5.4kg reduction of fat body mass in men with testosterone levels over 11.0nmol/L when compared with men who had testosterone levels under 11.0nmol/L.
You can read more about testosterone and weight loss, here.
Can Testosterone Increase Size?
It’s a well-known fact that testosterone has the capacity to increase muscle mass, which is why there are testosterone booster supplements available.
But how does this happen? The more testosterone in the body increases the rate of protein synthesis within the muscle (Griggs et al., 1989). This is because of a small change that has a massive knock on effect.
Firstly, the muscle fibre diameter increases to allow enhanced blood flow, this leads to an increase in muscle protein synthesis in the sarcoplasm. Finally, this increases synthesis of non-muscular (blood vessels and erythrocytes) which contributes to protein synthesis within the muscle and in turn increases muscle mass (Griggs et al., 1989).
However, in a study conducted by Griggs et al., (1989) muscle mass had increased but muscular strength had not. It had also been reported that lower levels of testosterone had been related to loss of muscle mass Yuki et al., (2013). Yuki et al., (2013) stated that protein synthesis is stimulated by testosterone along with preventing protein degradation within muscle cells.
Furthermore, testosterone increases satellite cell replication and activation resulting in an increase in muscle mass. From these two articles above both reporting muscle mass is related to testosterone levels it shows these results are reliable.
Can the Andropause or Hypogonadism Cause Heart Problems?
As previously stated, testosterone can help reduce risk factors diseases such as; cardiovascular disease and coronary heart disease (Saad, 2012; Kelly and Jones, 2013).
One risk factor that testosterone help reduce are hypertension (high blood pressure) which occurs when a diet is extremely rich in carbohydrates, fats and alcohol (Jiang et al., 2016).
These poor diet choices produce triglycerides in the blood that add to the formation of atherosclerosis (Jiang et al., 2016). This results in fat being accumulated in branch vessels which in turn blocks the blood flow of large arteries (Jiang et al., 2016). Wang et al., (2011) reported that low testosterone levels were associated with hypertension.
This is supported by Webb et al., (1999) who stated that testosterone administration caused dilation of coronary arteries, resulting in there being less chance of coronary heart disease among individuals with higher testosterone levels.
In more recent times Jones (2010) also reported that there is an increased risk of hypertension when testosterone levels are low. This is because of a reduction of tissue plasminogen activator and increased fibrinogen and plasminogen activator, which increases clotting in the blood vessels and arteries (Jones, 2010).
Testosterone and Insulin
Another risk factor that testosterone lessons is insulin resistance which as recently reported above as vital as it regulates the majority of the aspects of adipocyte biology (Kahn and Flier, 2000).
Jones (2010) states that decreased testosterones levels increase body fat which in turn exacerbates insulin resistance. Yialamas et al., (2007) conducted a study on acute testosterone withdrawal. Testing was 2 weeks long and included fourteen men.
However, two participants couldn’t complete testing. The results of this testing showed insulin sensitivity had reduced due to the withdrawal of testosterone from the twelve men.
This suggests that lesser testosterone levels reduce insulin resistance. Thus, increasing body weight, which leads hypertension and finally, diseases like cardiovascular or heart.
Pitteloud et al., (2005) reported on 60 males and found that testosterone levels were positively correlated with insulin resistance (P = 0.005). this is further backing up that testosterone is vital for the body to function effectively.
As we can see from the above research the benefits of testosterone are vastly great and showcase how beneficial it is towards not only physical but also mental health.
Testosterone and age
As previously discussed, testosterone has many benefits but do testosterone levels start to decrease as we age?
The simple answer to this is yes.
However, there is a lot more too it than it just decreases. As people age there are many physiological changes that happen within the body (reduction in bone health, muscular strength and fat free mass) (Chin et al., 2012).
It is also now recognised that age is associated with the decline of testosterone in males (Chin et al., 2012).
One reason for this is the increase of the serum sex hormone binding globulin in men, which reduces testosterone availability even further (Feldman et al., 2002).
This decline of testosterone phenomenon is called ‘late onset hypogonadism’ (Wang et al., 2009) or ‘testosterone deficiency syndrome’ (Morales et al., 2006).
The ages between thirty five to forty it has been suggested that it isn’t uncommon for a man’s testosterone levels to decrease by one percent every year (Davis and Doerr, 2019).
One reason testosterone level’s start to decrease at the age is because of external factors in their life such as; work responsibilities, family responsibilities, injuries and weight gain.
These factors hinder the opportunity to be able exercise regularly or play once loved sports (Vingren et al., 2010). Another reason for this natural drop off is the increase the serum sex hormone binding globulin in men, which as already discussed above reduces testosterone availability even further (Feldman et al., 2002).
Hakkinen et al., (2000) conducted a 6-month strength training study on men aged 40. Results of this testing showed that there were no significant changes in testosterone concentration.
Chin et al., 2012 conducted a study into whether or not testosterone did decrease with age. However, no significant findings were found.
In light of this testing would need to be completed over a ten to twenty years time span to be able to collect viable results in this area. No significant findings were also found from testing by Trumble et al., (2013), Nguyen et al., (2015) and Resnick et al., (2017) showing that there is a need for this to be investigated in great depth.
Does weightlifting raise testosterone?
Weightlifting is most commonly known for its bulking and build-up of muscle mass. However, it has been recognised that there may be more benefits to weightlifting on health than just an increase in muscle mass.
Some of the of the perceived health benefits are as follows; improved posture, sleep, mood, energy levels, keeps bones strong and healthy, boosts metabolism and fat loss. Furthermore, weightlifting regulates insulin, lowers inflammation and reduces risks of injury (Chai, 2017).
One of the key benefits of weightlifting on health is its ability to reduce risk of injury. Kite, Lloyd and Hamill (2016) state that weightlifting is far superior to other types of resistance training in developing physical qualities.
The reason why this type of exercise reduces injury risk is because it strengthens bones, resulting in them being less likely to break or fracture.
Pierce et al., (2008) conducted a literature review on weightlifting and resistance training. The result supported that weightlifting does improve posture, sleep, mood, energy levels, bone strength, metabolism, fat loss and risk of injury.
Similarly, Hendrick and Wada (2008) found vast benefits of weightlifting on athletic performance with the reasons for this being a reduced injury risk and improved bone strength. These studies suggest good evidence to include weightlifting in everyday life to help improve one’s health.
Weightlifting also benefits testosterone.
There are four main factors that weightlifting effects.
Firstly, is weight. This is because the lower percentage of body fat the higher amount of testosterone levels.
Secondly, age has shown to decrease testosterone levels. So, weightlifting can in the short-term increase testosterone levels in aging males.
Thirdly, fitness levels affect the amount testosterone is released. This is because the body needs to time to adjust to the demands of the exercise. Meaning, lower fitness levels result in a higher testosterone release.
Finally, the time of day effects testosterone levels while weightlifting. This is because testosterone is at its highest in the mornings, which therefore, shows that training at the end of the day will give the biggest boost to testosterone levels (CP and R, 2018).
Evidence shows that aging does impact testosterone levels and that weightlifting may be the answer to these problems.
Bjornebekk et al., (2021) conducted a study on 118 males with an age range of 12-52. They completed testing on the weightlifting, testosterone and age. The results showed that weightlifting reduced the brain to actual age gap because of the higher concentration of testosterone in the body.
This is also supported by Juan (2019) who reported that aging does decrease testosterone levels. The study Juan (2019) conducted consisted of twelve males with a mean age of 39 years old.
The results found that after 30 minutes of moderate intensity weightlifting testosterone levels had risen. This shows the importance of weightlifting training on an aging body.
Why do Compound Exercises Increase Androgens?
A compound exercise is an exercise. This type of exercise works multiple muscle groups at the same time.
An example of this is a squat which works the calves, glutes and quadriceps. Also, compound exercises can be combined to target even more muscle groups, such as; a lunge with a bicep curl.
Compound exercise are different from isolation exercises are isolation exercise only work a single muscle group. An example of this is a traditional bicep curl (Chertoff and Bubnis, 2019).
Compound exercises have been shown to be beneficial for burning more calories, improve intramuscular coordination, elevating heart rate, improving flexibility, improving strength and gaining muscle mass (Chertoff and Bubnis, 2019).
Furthermore, compound exercises make efficient use of your time as you work more muscle groups in a shorter amount of time (Chertoff and Bubnis, 2019).
There is also evidence that shows that compound exercises do influence testosterone levels.
Simao et al., (2013) conducted a study on the upper body compound exercises and hormonal responses. Twenty male subjects completed two weightlifting sessions.
After testing was complete the results stated that after compound exercises there was an increase in testosterone levels in the body. The reason for this could be because the exercises were performed on a larger muscle group when compared isolation exercise.
Similarly, this is supported by Emami et al., (2016) who conducted a study on eighty-three males. The subjects completed a sixteen-week moderate intensity compound exercise training programme.
After the training programme had ended, testosterone levels had shown to increase. This result further backs up that compound exercises are most beneficial towards increasing testosterone levels.
Excessive Endurance Exercise and Testosterone
Endurance exercise has its many benefits towards health (Ruegsegger and Booth, 2018). One benefit is an improvement of cardiorespiratory fitness which is measured through a VO2max test. Myers et al., (2002) found an increase of 12% in the VO2max performance after an endurance training programme.
There are many other benefits such as; a reduced hypertension, obesity, osteoarthritis, bone fractures, metabolic syndrome etc (Ruegsegger and Booth, 2018).
However, excessive endurance exercise can have its negative effects on testosterone levels in the body (Ramos, 2019).
Piedmont Healthcare (2021) reported that high endurance athletes have a decrease in testosterone this is because of the higher levels of cortisol.
This means the more endurance exercise you do, the more muscle tissue you will break down. Hackney (1989) reported that since endurance training reduces testosterone levels it also reduces a male’s sperm count, resulting in males being less likely to reproduce.
Weightlifting and testosterone conclusion
Throughout this article key areas of testosterone had been discussed as stated in the introduction. From this article it is clear to see how testosterone benefits the body not only physically but also mentally.
This shows that testosterone upholds a great importance in the maintenance of day to day bodily functions.
The key points that have been brought to light from this article are testosterones ability to fight depression, reduce risk factors of diseases, the effect age has on testosterone levels, the impact weightlifting has on health (improves posture and reduces risk of injury), the impact weightlifting has on testosterone, how compound exercises effect testosterone levels and finally, the negative effects of endurance exercise.
Overall, testosterone is very beneficial towards the health of an individual and supplementation should be used to be able to meet the demands of life.
References:
Almeida, O.P. Yeap, B.B. Hankey, G.J. Jamrozik, K. and Flicker, L. (2008) Low free testosterone concentration as a potentially treatable cause of depressive symptoms in older men. Archives of general psychiatry, 65(3), pp.283-289. Available at: https://pubmed.ncbi.nlm.nih.gov/18316674/
Bjørnebekk, A. Kaufmann, T. Hauger, L.E. Klonteig, S. Hullstein, I.R. and Westlye, L.T. (2021) Long-term Anabolic–Androgenic Steroid Use Is Associated With Deviant Brain Aging. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 6(5), pp.579-589. Available at: https://www.sciencedirect.com/science/article/pii/S2451902221000197
Chai, C. (2017) 8 reasons why weight training is incredible for your health [Online] Available from: < https://globalnews.ca/news/3513498/8-reasons-why-weight-training-is-incredible-for-your-health/ > [Accessed 10 June 2017].
Chertoff, J. Bubnis, D. (2019) How to Add Compound Exercises to Your Workout Routine [Online] Available from: < https://www.healthline.com/health/fitness-exercise/compound-exercises > [Accessed 12 November 2019).
Chin, K.Y. Soelaiman, I.N. Naina Mohamed, I. Shahar, S. Teng, N.I.M.F. Suhana Mohd Ramli, E. Ahmad, F. Aminuddin, A. and Zurinah Wan Ngah, W. (2012) Testosterone is associated with age-related changes in bone health status, muscle strength and body composition in men. The Aging Male, 15(4), pp.240-245. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4363070/
CP and R (2018) The impact exercise has on testosterone levels in males and females [Online] Available from: < https://www.cpandr.co.uk/2018/08/22/the-impact-exercise-has-on-testosterone-levels-in-males-and-females/ > [Accessed 22 August 2018]
Davis, C. Doerr, S. (2019) High and Low Testosterone Levels in Men [Online] Available from: < https://www.medicinenet.com/high_and_low_testosterone_levels_in_men/views.htm > [Accessed 9 June 2019].
Emami, A. Nazem, M.R. Hedayati, M. and Karami, M. (2016) Four months of combined and compound morning training improves testosterone/cortisol ratio, adiponectin and insulin resistance in male students. Sport Sciences for Health, 12(2), pp.215-220.
Feldman, H.A. Longcope, C. Derby, C.A. Johannes, C.B. Araujo, A.B. Coviello, A.D. Bremner, W.J. and McKinlay, J.B. (2002) Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study. The Journal of Clinical Endocrinology & Metabolism, 87(2), pp.589-598. Available at: https://pubmed.ncbi.nlm.nih.gov/11836290/
Griggs, R.C. Kingston, W.I.L.L.I.A.M. Jozefowicz, R.F. Herr, B.E. Forbes, G.I.L.B.E.R.T. and Halliday, D.A.V.I.D. (1989) Effect of testosterone on muscle mass and muscle protein synthesis. Journal of Applied Physiology, 66(1), pp.498-503. Available at: https://journals.physiology.org/doi/abs/10.1152/jappl.1989.66.1.498?journalCode=jappl
Hakkinen, K. Pakarinen, A. Kraemer, W.J. Newton, R.U. and Alen, M. (2000) Basal concentrations and acute responses of serum hormones and strength development during heavy resistance training in middle-aged and elderly men and women. Journals of Gerontology-Biological Sciences and Medical Sciences, 55(2), p.B95. Available at: https://pubmed.ncbi.nlm.nih.gov/10737684/
Hackney, A.C. (1989) Endurance training and testosterone levels. Sports Medicine, 8(2), pp.117-127. Available at: https://pubmed.ncbi.nlm.nih.gov/2675257/
Hedrick, A. and Wada, H. (2008) Weightlifting movements: do the benefits outweigh the risks?. Strength & Conditioning Journal, 30(6), pp.26-35. Available at: https://journals.lww.com/nsca-scj/Fulltext/2008/12000/Weightlifting_Movements__Do_the_Benefits_Outweigh.3.aspx
Jiang, S.Z. Lu, W. Zong, X.F. Ruan, H.Y. and Liu, Y. (2016) Obesity and hypertension. Experimental and therapeutic medicine, 12(4), pp.2395-2399. Available at: https://pubmed.ncbi.nlm.nih.gov/27703502/
Kahn, B.B. and Flier, J.S. (2000) Obesity and insulin resistance. The Journal of clinical investigation, 106(4), pp.473-481. Available at: https://www.jci.org/articles/view/10842
Kalinchenko, S.Y. Tishova, Y.A. Mskhalaya, G.J. Gooren, L.J. Giltay, E.J. and Saad, F. (2010) Effects of testosterone supplementation on markers of the metabolic syndrome and inflammation in hypogonadal men with the metabolic syndrome: the double‐blinded placebo‐controlled Moscow study. Clinical endocrinology, 73(5), pp.602-612. Available at: https://pubmed.ncbi.nlm.nih.gov/20718771/
Kelly, D.M. and Jones, T.H. (2013) Testosterone: a metabolic hormone in health and disease. J Endocrinol, 217(3), pp.R25-45. Available at: https://pubmed.ncbi.nlm.nih.gov/23378050/
Kite, R. Lloyd, R. and Hamill, B. (2016) British weight lifting position statement; youth weightlifting. Available at:https://britishweightlifting.org/resources/youth-position-statement-270918145402.pdf
Kelly, D.M. and Jones, T.H. (2015) Testosterone and obesity. Obesity Reviews, 16(7), pp.581-606. Available at: https://onlinelibrary.wiley.com/doi/abs/10.1111/obr.12282
Lépine, J.P. and Briley, M. (2011) The increasing burden of depression. Neuropsychiatric disease and treatment. 7(Supply 1), p.3. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3131101/
Morales, A. Schulman, C.C. Tostain, J. and Wu, F.C. (2006) Testosterone deficiency syndrome (TDS) needs to be named appropriately–the importance of accurate terminology. Available at: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.623.2609&rep=rep1&type=pdf
Myers, J. Prakash, M. Froelicher, V. Do, D. Partington, S. and Atwood, J.E. (2002) Exercise capacity and mortality among men referred for exercise testing. New England journal of medicine, 346(11), pp.793-801. Available at: https://pubmed.ncbi.nlm.nih.gov/11893790/
Neolife (2018) Testosterone: the pleiotropic hormone [Online] Available from: < https://www.neolifesalud.com/blog/testosterone-the-pleiotropic-hormone/?lang=en > [Accessed 18 December 2018].
Nguyen, C.P. Hirsch, M.S. Moeny, D. Kaul, S. Mohamoud, M. and Joffe, H.V. (2015) Testosterone and “age-related hypogonadism”—FDA concerns. N Engl J Med, 373(8), pp.689-691. Available at: https://europepmc.org/article/med/26287846
Parker, A.G. and Bailey, A.P. (2018) Exercise for adolescents and young people with mental illness. Exercise-Based Interventions for Mental Illness, pp.149-167. Available at: https://www.elsevier.com/books/exercise-based-interventions-for-mental-illness/stubbs/978-0-12-812605-9
Patel, A.S. Leong, J.Y. Ramos, L. and Ramasamy, R. (2019) Testosterone is a contraceptive and should not be used in men who desire fertility. The world journal of men's health, 37(1), pp.45-54.
Piedmont Healthcare (2021) The best exercises to increase testosterone [Online] Available from: < https://www.piedmont.org/living-better/the-best-exercises-to-increase-testosterone > [Accessed 2021].
Pierce, K. Brewer, C. Ramsey, M. Byrd, R. Sands, W.A. Stone, M.E. and Stone, M.H. (2008) Youth resistance training. Profess Strength Cond, 10, pp.9-23. Available at: https://www.iscaustralia.edu.au/wp-content/uploads/woods-b-jasc-2703.pdf
Ruegsegger, G.N. and Booth, F.W. (2018) Health benefits of exercise. Cold Spring Harbor perspectives in medicine, 8(7), p.a029694. Available at: https://pubmed.ncbi.nlm.nih.gov/28507196/
Ramos, T. (2019) Testosterone is Important for Optimal Health. Power, 30(2020).
Saad, F. (2012) Androgen therapy in men with testosterone deficiency: can testosterone reduce the risk of cardiovascular disease?. Diabetes/metabolism research and reviews, 28, pp.52-59. Available at: https://onlinelibrary.wiley.com/doi/10.1002/dmrr.2354
Simão, R. Leite, R.D. Speretta, G.F.F. Maior, A.S. De Salles, B.F. de Souza Junior, T.P. Vingren, J.L. and Willardson, J.M. (2013) Influence of upper-body exercise order on hormonal responses in trained men. Applied Physiology, Nutrition, and Metabolism, 38(2), pp.177-181. Available at: https://www.cabdirect.org/globalhealth/abstract/20133103009
Svartberg, J. Agledahl, I. Figenschau, Y. Sildnes, T. and Jorde, R. (2008) Testosterone treatment in elderly men with subnormal testosterone levels improves body composition and BMD in the hip. International journal of impotence research, 20(4), pp.378-387. Available at: https://www.nature.com/articles/ijir200819
Trumble, B.C. Cummings, D.K. O’Connor, K.A. Holman, D.J. Smith, E.A. Kaplan, H.S. and Gurven, M.D. (2013) Age-independent increases in male salivary testosterone during horticultural activity among Tsimane forager-farmers. Evolution and Human Behavior, 34(5), pp.350-357. Available at: https://pubmed.ncbi.nlm.nih.gov/24187482/
Vingren, J.L. Kraemer, W.J. Ratamess, N.A. Anderson, J.M. Volek, J.S. and Maresh, C.M. (2010) Testosterone physiology in resistance exercise and training. Sports medicine, 40(12), pp.1037-1053. Available at: https://link.springer.com/article/10.2165%2F11536910-000000000-00000
Wang, C. Jackson, G. Jones, T.H. Matsumoto, A.M. Nehra, A. Perelman, M.A. Swerdloff, R.S. Traish, A. Zitzmann, M. and Cunningham, G. (2011) Low testosterone associated with obesity and the metabolic syndrome contributes to sexual dysfunction and cardiovascular disease risk in men with type 2 diabetes. Diabetes care, 34(7), pp.1669-1675. Available at: https://pubmed.ncbi.nlm.nih.gov/21709300/
Wang, C. Nieschlag, E. Swerdloff, R. Behre, H.M. Hellstrom, W.J. Gooren, L.J. Kaufman, J.M. Legros, J.J. Lunenfeld, B. Morales, A. and Morley, J.E. (2009) ISA, ISSAM, EAU, EAA and ASA recommendations: investigation, treatment and monitoring of late-onset hypogonadism in males. International journal of impotence research, 21(1), pp.1-8. Available at: https://pubmed.ncbi.nlm.nih.gov/18955511/
Webb, C.M. Adamson, D.L. de Zeigler, D. and Collins, P. (1999) Effect of acute testosterone on myocardial ischemia in men with coronary artery disease. American Journal of Cardiology, 83(3), pp.437-439. Available at: https://www.ahajournals.org/doi/10.1161/01.CIR.100.16.1690
Yuki, A. Otsuka, R. Kozakai, R. Kitamura, I. Okura, T. Ando, F. and Shimokata, H. (2013) Relationship between low free testosterone levels and loss of muscle mass. Scientific reports, 3(1), pp.1-5. Available at: https://www.nature.com/articles/srep01818