Testosterone and You
If you’re a regular reader of my columns, you are more than likely well versed in the benefits of healthy testosterone levels. In this column, I plan to breakdown some research on naturally boosting your testosterone levels. First, for those who need a little refresher, we will go over the physiology and relative importance of boosting testosterone. Then we will review the various ways that exercise, diet, and nutritional supplementation can boost testosterone and improve your performance.
Testosterone is a steroid hormone made from cholesterol in the testes and is released in a circadian fashion. The term “circadian” refers to the daily rise and fall of testosterone with the highest levels generally occurring in the morning and lowest at bedtime; hence morning erections. This must be kept in mind when assessing your own testosterone with blood work. Be consistent in the time at which you have your levels drawn in a lab. Moreover, if you notice that your morning erections are getting soft or not at all, get your morning testosterone levels checked as you are likely deficient.
Women, we aren’t forgetting you here! If you are having a hard time getting in shape, have low libido, or just feel sluggish get your testosterone checked. If you are over 40, check your levels regardless!
Testosterone production and release is controlled by the hypothalamus. The hypothalamus has intricate connections to higher brain functions which make it sensitive to environmental stress and stimuli. Many events in your world can effect testosterone production such as driving a fast car, seeing a sexy person, jumping out of a plane, or squatting 400lbs. The hypothalamus releases luteinizing hormone-releasing hormone (LHRH) which acts directly on the pituitary gland to stimulate release of luteinizing hormone (LH). LH then reaches the testes where it stimulates testosterone production and release. In women, the ovaries and adrenal glands act as sources of testosterone.
Testosterone is carried through the blood on proteins. In particular, the protein sex hormone-binding globulin (SHBG) carries up to 60% of your testosterone. The rest is bound to serum albumin and a small fraction, usually around 2% is free or unbound. The “free” fraction is the most active form of the hormone. The free testosterone interacts with receptors inside your cells that act directly on DNA to make specific proteins to promote its agenda. Testosterone can also act through derivatives dihydrotestosterone (DHT) made by 5α-reductase and estrogen made by aromatase.
Testosterone’s agenda is to make you a man, or give a woman vitality, albeit in smaller amounts. Testosterone plays a vital role in development from the point of conception and well into old age. The development of male sexual characteristics is a result testosterone’s anabolic (muscle building) and androgenic (body hair, sex drive, etc) activity rising during critical phases in development like puberty. Aging beyond 35-40 years is associated with a 1-3% decline per year in circulating testosterone concentration in men (1).
MUSCULAR DEVELOPMENT AND FAT
When testosterone acts on a muscle cell it has multiple actions that increase muscle protein content. First, it stimulates the uptake of amino acids into muscle cells and promotes the synthesis of muscle proteins. Second, testosterone has anti-catabolic properties, which is to say that it prevents the breakdown of muscle. It does this by limiting muscle glycogen breakdown and blocking the effect of the hormone cortisol. Cortisol is released as a result of external environmental stress which leads to a need for the mobilization of carbohydrates and consumption of muscle proteins for vital functions; it is the quintessential catabolic hormone.
Free testosterone levels correlate well with muscle strength, bone mineral density, and lower levels of body fat in elderly men. Obesity is associated with physiological changes in circulating sex steroid levels. Obese men have more aromatase activity which is an enzyme that converts testosterone to estrogens in peripheral tissues such as fat. Circulating levels of testosterone lower than 230ng/dL are associated with severe impairments in body composition and glucose metabolism. Many correlations can be made between low testosterone and the “metabolic syndrome” of insulin resistance, abnormal cholesterol, high blood pressure, and abdominal obesity.
Thus, maintaining and improving testosterone levels has been a topic of great interest to doctors and athletes alike ever since its discovery. As levels of testosterone drop with age men in their 40s to 50s may relate to feelings of fatigue, depression, loss of vitality, decreased libido, and loss of strength and muscle mass. Some think it really isn’t so much where your testosterone levels are at, but more where they are going. As we said earlier there is quite a significant variation in testosterone levels throughout the day so it takes relatively large drops or rises to break a threshold that results in symptoms or improvements muscle, respectively.
When we examine rises and falls in testosterone as a result of exercise or nutritional supplements we must keep this threshold in mind. Small changes in testosterone throughout the day are unlikely to have a large impact on muscle growth and recovery. Anyone who has taken testosterone injections will tell you that unless you’re taking 300mg or more per week you are not going to get a significant bodybuilding response. This type of dosing can bring someone easily from a level of 400 to 1200 or a 300% rise in your levels. So we must be cautious when we look at nutritional supplement studies that raise measured testosterone by 20 or even 40% and jump to conclusions that this will lead to significant body composition changes. In fact, the best way to experience a rise in testosterone AND experience body composition changes is to raise your levels with proper exercise and nutrition.
EXERCISE, REST, AND TESTOSTERONE LEVELS
As we discussed, testosterone builds muscle and so does exercise. There is a definite correlation between elevated testosterone and muscle growth. Weight training stimulates muscle strength and hypertrophy (growth) which is in part due to increases in testosterone.
Most bodybuilders understand that there is a constant battle in the body between catabolic cortisol and anabolic testosterone. Some believe that doing concurrent strength training with aerobic conditioning puts these hormones in competition with one another. Plenty of research shows that overtraining or long distance endurance training results in significant elevations is cortisol and these are sustained elevations over weeks of training.
Weight training can cause a cortisol stress response but the body quickly adapts and the levels drop for the same intensity of training as testosterone elevates or stays the same. The cortisol response may be even more pronounced in women (2). However, research supports that strength training can restore the anabolic balance to moderate endurance training. Better yet, high intensity interval endurance training supports healthy testosterone increases by 60 to 97% (5). Evidence also confirms that changes in testosterone or cortisol concentrations can support neuromuscular performance through various short-term mechanisms (e.g. second messengers, lipid/protein pathways, neuronal activity, behavior, cognition, motor-system function, muscle properties and energy metabolism) (4).
Loebel and Kraemer explained the testosterone response to exercise succinctly (3). There are many variables to weight training programs, and they can affect the endocrine response to that training. Varying the exercises, order of exercise, sets, rest between sets, reps and weight can all affect testosterone levels. Kraemer showed that training for muscle growth with 10 rep maximums for multiple exercises with 1 min rests produced a greater magnitude of increase in testosterone than a 5 rep maximum load with 3 min rest. Overall the testosterone response post-exercise is fairly consistent with many variations in volume and intensity of weight training for mass. However, looking at the numbers closely we are talking about a rise in levels of testosterone on a magnitude of 15-20% on average or maximally 90-100% with HIIT. Although this is better than a drop seen with many forms of lengthy endurance exercise, this is very small when you consider the effects of supplemental testosterone which can increase levels by 300 to 500% from baseline. Nonetheless, even short-term rises above baseline have beneficial effects on exercise physiology as supported by literature.
Most importantly and left for last, rest and recovery are of great importance in maintaining healthy testosterone levels. Overtraining, regardless of the type of exercise performed increases cortisol levels and depresses testosterone levels. Many of the recuperative effects controlled by anabolic hormones are affected by sleep. Hormones such as testosterone and growth hormone rise after a good night of sleep. Remember, what you do outside the gym is often as important or more important than what you do inside the gym. That’s why we call it a bodybuilding LIFESTYLE.
NUTRITION, SUPPLEMENTS, AND TESTOSTERONE LEVELS
There are many studies, old and new, that support the effects that diet can have on endocrine responses in humans and animals. On the extremes, such as a vegetarian diet or very low calorie diets, we know that these can be detrimental to testosterone levels (6, 7). High fiber and low cholesterol or diets severely restricted in fat reduce the availability of the precursors of testosterone synthesis and can potentially decrease testosterone levels. Additionally, diets with protein providing more that 40% of calories vs. 15% protein calories have higher testosterone levels in some studies but the effects of macronutrient composition on endocrine function is inconsistent and controversial.
Recent animal studies on prostate cancer looked into the effects of high omega-6 fatty acid diets (like much of the western world) and changing the diet to one that was high in omega-3 fatty acids like fish oil (9). Mice fed a high omega-3 diet had slightly lower plasma testosterone level at 24 and 40 weeks, significantly lower estrogen levels at 40 weeks and significantly less expressed androgen receptors in the prostate at 40 weeks. Interesting research nonetheless, but I always hesitate to extrapolate effects on rodents to potential effects on humans. The research presented just SUGGESTS a correlation between omega-3 fatty acids and hormone levels and supports a need for further research.
Along similar lines recent studies have suggested that conjugated linoleic acid (CLA) may affect testosterone production (8). CLA supplementation to animals and overweight people significantly reduces body fat mass although this response is attenuated in well trained individuals. Since testosterone is well known to have similar actions in supporting lean body mass, researchers explored a correlation between CLA and testosterone production. Filippo Macaluso et al. demonstrated a direct effect of CLA on testosterone producing cells in culture, but failed to demonstrate significant elevations after supplementation in humans. This research shows some promise and perhaps through variations in the research protocol further correlations may surface.
When you go to your favorite online store, you will find all sorts of supplements that claim to raise your testosterone levels. There are many different herbs and plant derived compounds that can affect your testosterone levels, but most of the research is quite superficial, inconsistent and heavily biased by manufacturers. That being said there are a few compounds that are worth noting as they have some relatively stronger research backing. Also I must note that even though these compounds have been shown to have modest effects on testosterone levels (mostly in animals), often this has not been correlated to improved physiques or strength.
Tribulus terrestris (TT) is a flowering plant found in the temperate and tropical regions of Southern Asia, Africa, and Australia. It has long been described as a treatment for male sexual dysfunction and was popularized by research from a Bulgarian pharmaceutical company with Tribestan suggesting it could increase testosterone. However, these studies aren’t available for scrutiny. Multiple studies have been performed in rodents and have demonstrated an increase in testosterone levels with TT feeding. Conversely human trials of isolated TT extract supplementation have failed to show consistent rises in testosterone and/or accretion of lean body mass without having significant industry bias (10, 11, 12). If you’re looking for a boost in libido, this may be the main benefit here.
D-Aspartic Acid (DAA) is an amino acid found concentrated in the testes, hypothalamus, and pituitary. Italian scientists published a study in 2009 which brought DAA to the forefront in testosterone boosters (13). Feeding DAA to rats is capable of eliciting the release of the gonadotropin-releasing hormone (GnRH) from the hypothalamus, the luteinizing hormone (LH) and the growth hormone (GH) from the pituitary gland, and testosterone from the testes. Furthermore, supplementing humans with 12 days of 3.12g of DAA resulted in nearly a 30% increase in serum testosterone levels. The “however” is that DAA can accumulate in tissues and it is not clear how safe this is so I would recommend limiting the dose to 1g per day for a maximum of 8 weeks until further testing can be done.
Astaxanthin + Saw Palmetto is an herbal combination that in-vitro studies demonstrated a significantly greater inhibition of the enzyme 5α reductase (converts T to DHT) and aromatase (converts T to E) (14). This herbal combination produced significant increases in serum testosterone levels up to 60% while decreasing estrogen and DHT. A dose of 800 and 2000mg were shown to equally raise testosterone levels, while 2000mg further increased the drop in estrogen. BIAS ALERT: the study was funded by the company that made the product.
Fenugreek, Trigonella foenum graecum, commonly used as a spice in Middle Eastern countries and widely used in south Asia and Europe, are known to have anti-diabetic properties and an ability to boost testosterone levels. Interestingly it contains an unusual amino acid 4-hydroxyisoleucine, so far found only in fenugreek, which has anti-diabetic properties of enhancing insulin secretion under hyperglycaemic conditions, and increasing insulin sensitivity (15, 16). Its ability to raise testosterone levels and improve insulin action explains its ability to produce an anabolic effect in humans and rats (16). In addition to doubling testosterone levels, Fenugreek has even been shown at a dose of 500mg to significantly impact both upper- and lower-body strength and body composition in comparison to placebo in a double blind controlled trial (17). Despite some good research, further evaluation of Fenugreek extract in resistance-trained males showed only a significant decrease in DHT levels and without a boost in testosterone (18).
Two other herbals are supported by human clinical studies to increase testosterone both at a dose of 5g/d: Macuna Pruriens and Withania Somnifera (19, 20). These can significantly increase serum testosterone levels but in relatively high dosing and after 3 to 5 months of use. With such high dosing using these compounds may be a little impractical until exercise related studies show them to be beneficial.
In conclusion, testosterone plays a critical role in muscle anabolism and making you a healthy man. You should have your levels checked, especially if you are symptomatic of LowT. If you plan to focus your diet or supplement routine on boosting testosterone levels don’t go at it blindly. Just like watching your poundage’s on the bench or your weight on the scale you should check your baseline morning testosterone level. If you take any of the above supplements, recheck your levels in a month or 2. If your levels go up and see improvements in the gym you can record your own statistical significance.
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