In addition to its role as a natural hormone, testosterone is used as a medication, for instance in the treatment of low testosterone levels in men and breast cancer in women.[10] Since testosterone levels decrease as men age, testosterone is sometimes used in older men to counteract this deficiency. It is also used illicitly to enhance physique and performance, for instance in athletes.
How to do it: From your hands and knees, move your hands out from under your shoulders so your arms are extended at roughly a 45° angle. Tuck your toes under your feet. As you exhale, straighten your legs and lift your butt and midsection toward the ceiling. Your knees should be slightly bent, and you should be up on your toes. Now drop your head between your arms, straighten your arms and legs, and push back on your feet. Press your heels into the floor, or as far as you can go. Hold for two seconds.
Kornblum, C., Schroder, R., Muller, K., Vorgerd, M., Eggers, J., Bogdanow, M., Papassotiropoulos, A., Fabian, K., Klockgether, T., and Zange, J. Creatine has no beneficial effect on skeletal muscle energy metabolism in patients with single mitochondrial DNA deletions: a placebo-controlled, double-blind 31P-MRS crossover study. Eur J Neurol 2005;12:300-309. View abstract.

Bodybuilding is the use of progressive resistance exercise to control and develop one's musculature for aesthetic purposes.[1] An individual who engages in this activity is referred to as a bodybuilder. In professional bodybuilding, bodybuilders appear in lineups and perform specified poses (and later individual posing routines) for a panel of judges who rank the competitors based on criteria such as symmetry, muscularity, and conditioning. Bodybuilders prepare for competitions through the elimination of nonessential body fat, enhanced at the last stage by a combination of intentional dehydration and carbohydrate loading, to achieve maximum muscular definition and vascularity, as well as tanning to accentuate the contrast of the skin under the spotlights. Bodybuilders may use anabolic steroids and other performance enhancing drugs to build muscles.
Studies conducted in rats have indicated that their degree of sexual arousal is sensitive to reductions in testosterone. When testosterone-deprived rats were given medium levels of testosterone, their sexual behaviors (copulation, partner preference, etc.) resumed, but not when given low amounts of the same hormone. Therefore, these mammals may provide a model for studying clinical populations among humans suffering from sexual arousal deficits such as hypoactive sexual desire disorder.[37]
This content is strictly the opinion of Dr. Josh Axe and is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Axe nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.
Testosterone is available in different forms including patches, injections, and a topical gel which the body absorbs through your skin. The skin patch is applied once every 24 hours, usually in the evening, and it releases some amount of the hormone into the skin. The oral forms are usually attached to the gum or inner cheek twice daily from where it is absorbed into the bloodstream. After applying the topical gel over the body, it is important to wash your hands thoroughly to avoid exposing others to testosterone. The injections are usually administered every seven to 14 days depending on the formulation and the degree of deficiency of testosterone.
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T.[118] The T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.
Without supplementation, creatine is formed primarily in the liver, with minor contributions from the pancreas and kidneys. The two amino acids, glycine and arginine, combine via the enzyme Arginine:Glycine amidinotransferase (AGAT) to form ornithine and guanidoacetate. This is the first of two steps in creatine synthesis, and although rare, any deficiency of this enzyme can result in mild mental retardation and muscular weakness.[28] AGAT is also the primary regulatory step, and an excess of dietary creatine can suppress activity of AGAT to reduce creatine synthesis[29] by reducing AGAT mRNA levels, rather than resulting in competitive inhibition.[30]
Furthermore, because creatine can help restore ATP levels, increasing energy, it can lead to reduced amounts of heart muscle stress. More energy in your life will result in less pain, stress, and boost morale in everyday life which has a significant role in improving heart health. The increased capacity to exercise is also crucial in maintaining and improving heart health.
Don’t get us wrong—cardio is important for keeping your body fat down and keeping your heart health in check. (Bonus points if you run or bike, since outdoor exercise is linked to better energy and improved mental health.) But when it comes to building muscle, hitting the treadmill won't help you much. “Every component of exercise, minus cardio, can help with muscle hypertrophy,” which is the scientific term for muscle building, says Michelle Lovitt, an exercise physiologist and trainer in Los Angeles. “Cardio tends to burn calories and puts your body in a deficit, which is great for leaning out, but not building mass.”

While the number of reps you do per set is important, of equal importance is the total number of reps you do per muscle group. The National Strength and Conditioning Association has determined that, to maximize growth, you need approximately 20–70 total reps per muscle group. Depending on which end of a rep range you’re working, this can be done in one session or over a few days (a training week, for instance), but that’s the spread you need to cover to see gains.

Parashos, S. A., Swearingen, C. J., Biglan, K. M., Bodis-Wollner, I., Liang, G. S., Ross, G. W., Tilley, B. C., and Shulman, L. M. Determinants of the timing of symptomatic treatment in early Parkinson disease: The National Institutes of Health Exploratory Trials in Parkinson Disease (NET-PD) Experience. Arch Neurol. 2009;66(9):1099-1104. View abstract.

Without supplementation, approximately 14.6mmol (2g) of creatinine, creatine’s urinary metabolite, is lost on a daily basis in a standard 70kg male ages 20-39. The value is slightly lower in females and the elderly due to a presence of less muscle mass.[35] This amount is considered necessary to obtain in either food or supplemental form to avoid creatine deficiency. Requirements may be increased in people with higher than normal lean mass.[35][198] Creatine excretion rates on a daily basis are correlated with muscle mass, and the value of 2g a day is derived from the aforementioned male population with about 120g creatine storage capacity.[35] Specifically, the rate of daily creatine losses is about 1.6%[199]-1.7%,[25] and mean losses for women are approximately 80% that of men due to less average lean mass.[35] For weight-matched elderly men (70kg, 70-79 years of age) the rate of loss of 7.8mmol/day,[49] or about half (53%) that of younger men.


The gluteus maximus (also known collectively with the gluteus medius and minimus, as the gluteal muscles, and sometimes referred to informally as the "glutes") is the main extensor muscle of the hip. It is the largest and most superficial of the three gluteal muscles and makes up a large portion of the shape and appearance of each side of the hips. Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the buttocks.
The shortest and most preliminary study noted that, over the short term, creatine delivers on its expected improvement in physical strength. However, longer studies that measure the rate of loss for muscle function (deterioration of muscular capacity that is known to occur with ALS) have repeatedly failed to find a benefit with creatine supplementation.
The NitroSurge pre-workout supplement by Jacked Factory aims to get you pumped and focused before a gym session. Besides L-Citrulline, this supplement also contains performance-enhancing betaine anhydrous and beta alanine. It also contains L-theanine which has shown to inhibit nerve cell damage in one study.  For energy-boosting benefits, the NitroSurge is also equipped with caffeine and AstraGin for energy metabolism. Before you buy, consider if you fall under the following circumstances in which this pre-workout would be beneficial to you:

Perform bent over rows to work your back. Stand with your feet shoulder-width apart, about 6 to 10 inches (15–25 cm) behind the barbell or two dumbbells. Bend slightly at the knees but keep your shins vertical. Bend forward at the waist with your spine and head straight. Lift the weight with an overhand grip up to your lower chest or upper abdomen. Lower slowly until your arms are nearly extended, without touching the ground. 3 x 8.[5]


Standing with your feet hips distance apart, hold a barbell or free weights at shoulder height (either the barbell resting above your shoulder blades on your back, or free weights resting on top of your shoulder muscles held in front of you). Keeping your spine in a neutral position move into the squat by retracting your hips and pulling them backward. Hinging at your hips, bend your knees until your thighs come almost parallel to the ground (knees should be directly over your feet). Then push back up until your back is straight and repeat 5–10 times depending on the weight you’re using.
The winner of the annual IFBB Mr. Olympia contest is generally recognized as the world's top male professional bodybuilder. The winner of the Women's Physique portion of the competition is widely regarded as the world's top female professional bodybuilder. The title is currently held by Juliana Malacarne, who has won every year since 2014. Since 1950, the NABBA Universe Championships have been considered the top amateur bodybuilding contests, with notable winners such as Reg Park, Lee Priest, Steve Reeves, and Arnold Schwarzenegger. Winners generally go on to become professional athletes.
^ Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL (2017-06-13). "International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine". Journal of the International Society of Sports Nutrition. 14: 18. doi:10.1186/s12970-017-0173-z. PMC 5469049. PMID 28615996.
In 1912, Harvard University researchers Otto Folin and Willey Glover Denis found evidence that ingesting creatine can dramatically boost the creatine content of the muscle.[5][non-primary source needed] In the late 1920s, after finding that the intramuscular stores of creatine can be increased by ingesting creatine in larger than normal amounts, scientists discovered creatine phosphate, and determined that creatine is a key player in the metabolism of skeletal muscle. The substance creatine is naturally formed in vertebrates.[6]
It is regularly reported that creatine supplementation, when combined with heavy resistance training leads to enhanced physical performance, fat free mass, and muscle morphology [18-22]. A 2003 meta analysis [8] showed individuals ingesting creatine, combined with resistance training, obtain on average +8% and +14% more performance on maximum (1RM) or endurance strength (maximal repetitions at a given percent of 1RM) respectively than the placebo groups. However, contradicting studies have reported no effects of creatine supplementation on strength performance. Jakobi et al [23] found no effects of a short term creatine loading protocol upon isometric elbow flexion force, muscle activation, and recovery process. However, this study did not clearly state if creatine supplementation was administered concurrent with resistance training. Bemben et al [24] have shown no additional benefits of creatine alone or combined with whey protein for improving strength and muscle mass after a progressive 14 weeks (3 days per week) resistance training program in older men. These conflicting results can be explained by the possibility that the supplemented groups were formed by a greater amount of non-responders or even because creatine supplementation was administered on the training days only (3 times a week). This strategy has not been adequately tested as effective in middle aged and older men for maintaining post loading elevated creatine stores [5].

In a later study, it was found that biologically relevant concentrations (10-30mM) of creatine bind synthetic membranes with lipid compositions mimicking the inner mitochondrial membrane or plasma membrane in a concentration-dependent manner. This also conferred a degree of protection, increasing membrane stability in response to challenge from a number of destabilizing agents. Phosphocreatine was more effective than creatine in this context, although both were able to bind and stabilize membranes.[119]
D-aspartic acid can also help to reduce cortisol levels. Cortisol is known as the “stress” hormone because its production increases during stressful situations. High cortisol levels can have many negative side effects, such as weight gain, muscle tissue breakdown, or increased blood sugar. Taking a supplement that includes cortisol can reduce stress and prevent excess fat storage or muscle loss.
The other two, the medius and minimus, work together to aid your gluteus maximus in raising your leg to the side. Plus, those smaller glute muscles help rotate your thigh outwards when your leg is straight, and inwards when your hips are bent. Talk about a dream team! (To learn more about the workings of your glutes, check out The Women's Health Big Book of Exercises!)
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Creatine supplementation often causes weight gain that can be mistaken for increase in muscle mass. Increasing intracellular creatine may cause an osmotic influx of water into the cell because creatine is an osmotically active substance [10]. It is possible that the weight gained is water retention and not increased muscle. The retention of water may be connected to reports of muscle cramps, dehydration, and heat intolerance when taking creatine supplements. It would be prudent to encourage proper hydration for creatine users. Further research is needed to investigate these and other possible side effects.
To succeed and thrive as a bodybuilder, it takes more than overwhelming muscular strength or athletic prowess. Judges select bodybuilding champions based on muscle mass, definition, proportion, symmetry, and an athlete’s stage presence. Given the criteria, it is no surprise that most serious bodybuilders consider supplementation to be an essential component of their training regimen.
Once training is resumed under these conditions, there may be little in the way of caloric support to ensure that protein synthesis and muscle growth occurs. Muscle may even begin to cannibalize itself as the body enters into a catabolic state. Even with the best of diets this can sometimes happen if training demands override the nutritional balance or imbalance.
"A lot of the symptoms are mirrored by other medical problems," Hedges says. "And for a long time, we were not attributing them to low testosterone, but to diabetes, depression, high blood pressure, and coronary artery disease. But awareness and appreciation of low testosterone has risen. We recognize now that low testosterone may be at the root of problems."
Extracellular creatine (creatine outside of a cell) appears to influence creatine uptake into a cell. It seems that prolonged and excessive levels of creatine actually suppress uptake (a form of negative regulation to prevent excessive influx).[180] In vitro studies in rat muscle cells have shown that including 1mM creatine into cell culture medium substantially reduces creatine uptake into cells. The inhibitory effect was partially negated by protein synthesis inhibitors, suggesting that high levels of creatine induce the expression of a protein that suppresses creatine transporter activity.[180] Similar findings were reported in a later study in cultured mouse myoblasts, which noted a 2.4-fold increase in intracellular creatine levels in the presence of the protein synthesis inhibitor cyclohexamide.[174]
At the end of the day, you have to focus on how you feel. “Listen to your body,” says Davis. “It tells you when it needs a day off.” As a rule of thumb, take a rest day if your perceived pain is above a seven on a scale of 10, Davis advises. Or, focus on a different body part (say, if your legs are sore, focus on upper-body moves). Can't stop, won't stop—at least, till your next rest day.

Of course, cardio is an important part of fitness too, but the benefits of strength training are major. Strength training helps build muscle, and lean muscle is better at burning calories when the body is at rest, which is important whether you're trying to lose weight or maintain it. It also helps strengthens joints and bones, avoid injury, improve your muscular endurance, and will help you give it your all during your other workouts, whether that means setting a new PR if you're a runner or pushing (and pulling) a little harder with your legs during your favorite indoor cycling class.
It is possible that females could benefit more than males due to a combined lower creatine kinase activity as well as having altered purine metabolism during depression,[257] but no human comparative studies have been conducted yet. One rat study noted that creatine monohydrate at 2-4% of feed had 4% creatine able to exert anti-depressive and anxiolytic effects in female rats only.[228]
When splitting a sample into exercisers and non-exercisers, it appears that exercise as a pre-requisite precedes a higher range of activity. Inactive people tend to be on the lower end of creatine kinase activity and relatively clustered in magnitude, while exercise generally increases activity, but also introduces a larger range of possible activity.[56]
Don’t make the mistake of trying to bulk up when you should be on a diet. While you might have muscle on your mind, most people need to get leaner first. If you’re fat and you start eating for size, you’re only going to get fatter. Get rid of the excess blubber first, to the point where you can see some abs, and then worry about getting big. You should be as low as 12% body fat before you change your diet up to focus on mass gain. That will ensure that your insulin sensitivity is high. When it is, you can eat more carbs and your body won’t store them as fat.
In regard to practical interventions, concurrent glycogen loading has been noted to increase creatine stores by 37-46% regardless of whether the tissue was exercised prior to loading phase.[176] It is important to note, however, that creatine levels in response to the creatine loading protocol were compared in one glycogen-depleted leg to the contralateral control leg, which was not exercised.[176] This does not rule out a possible systemic exercise-driven increase in creatine uptake, and the increase in creatine noted above[176] was larger than typically seen with a loading protocol (usually in the 20-25% range). Consistent with an exercise-effect, others have reported that exercise itself increases creatine uptake into muscle, reporting 68% greater creatine uptake in an exercised limb, relative to 14% without exercise.[153]
If you'’re looking to add muscle mass to your frame, hitting the weights hard is a given. Quality time in the gym begins a cascade of changes that will stimulate your muscles to grow bigger in response to the challenges you throw their way. It'’s tempting to think that'’s all it takes to add muscle to your body. After all, you can actually feel your biceps growing after an intense set of curls.
Testosterone was first used as a clinical drug as early as 1937, but with little understanding of its mechanisms. The hormone is now widely prescribed to men whose bodies naturally produce low levels. But the levels at which testosterone deficiency become medically relevant still aren’t well understood. Normal testosterone production varies widely in men, so it’s difficult to know what levels have medical significance. The hormone’s mechanisms of action are also unclear.

Creatine supplementation at 300mg/kg for one week (loading with no maintenance) in youth subject to six repeated 35m sprints (10s rest, known as the Running-based Anaerobic Sprint Test or RAST) noted that the increased average and peak power output seen in creatine was not met with a reduction in fatigue, although there was an attenuation in inflammation from exercise (TNFα and CRP).[299]


Studies of so-called "smart drugs" have also been taken out of context. Some "smart" nutrients, available over the counter, are marketed as a way to "increase mental focus and concentration during training." The problem is that the studies they're based upon involved either animals or people with brain pathology. In normal people the effects of smart drugs remain unproven, except anecdotally.
Drink plenty of water throughout the day, especially in the hours leading up to your workout. This can help you feel full and reduce hunger pangs. During training, drink about 8 ounces every 15-20 minutes, more when it's hot and humid. The reason is simple: Your performance quickly begins to suffer when the body is dehydrated just 1%-–2%. And if you wait till you feel thirsty, you've waited too long. A flavorful, low-calorie sports drink is a great way to hydrate. Try drinking fluids stored at cooler temperatures; studies show that people consume more when the liquid is colder.
Neurological and cognitive function has also been shown to be improved by creatine supplementation [47,48]. Rawson and Venezia [49] review the effects of creatine supplementation on cognitive function highlighting that higher brain creatine has been associated with improved neuropsychological performance. Creatine supplementation protocols have been shown to increase brain creatine and phosphocreatine contents. Cognitive processing hindered due to sleep deprivation and natural impairment due to aging can be improved by creatine supplementation. This review also highlights other possible benefits of creatine ingestion to older adults, such as improvements in: fatigue resistance, strength, muscle mass, bone mineral density, and performance of activities of daily living. Some of these benefits occur without concurrent exercise. The authors inform that discrepancies between studies do exist and are hard to explain but may be possibly due to differences in diet, race and/or supplementation protocols. However, the ideal dose of creatine to maximize brain uptake is not known. Patients have been supplemented with 40 g while in healthy adults positive results have been reported with around 20 g per day [49].

Three additional studies suggest that creatine supplementation may not be beneficial for running velocity, sprint swimming performance, or a maximal cycling effort [7]. Short bouts of repeated anaerobic activity have shown some potential benefits with creatine supplementation use in a laboratory setting. However, creatine supplementation has not been shown to enhance single-event performance such as stationary cycling [16-19]. Taken together, these studies do not support creatine supplementation to enhance aerobic activities such as distance running.
After all, you’ve probably seen the countless workouts, diets, supplements, programs, products and people claiming that super fast muscle growth is possible. You’ve probably also seen the click-bait headlines (“How To Build 20lbs Of Muscle In Just 6 Weeks!”) and the unbelievable transformations of supposedly “natural” people (bodybuilders, celebrities, athletes, fitness gurus on social media, etc.) that clearly prove it can happen faster than this.
The majority of creatine in the human body is in two forms, either the phosphorylated form making up 60% of the stores or in the free form which makes up 40% of the stores. The average 70 kg young male has a creatine pool of around 120-140 g which varies between individuals [10,11] depending on the skeletal muscle fiber type [1] and quantity of muscle mass [11]. The endogenous production and dietary intake matches the rate of creatinine production from the degradation of phosphocreatine and creatine at 2.6% and 1.1%/d respectively. In general, oral creatine supplementation leads to an increase of creatine levels within the body. Creatine can be cleared from the blood by saturation into various organs and cells or by renal filtration [1].

As we all adjust to the time change, it’s worthwhile to consider how other aspects of our lives can sway our circadian rhythms. Circadian clocks govern the rhythms of sleep and activity in virtually all animals and are responsive to a variety of stimuli like light and stress. Research is starting to suggest that our eating patterns – specifically when we eat – can also have a pervasive impact.

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