A dose of 5g daily has strong evidence supporting it not causing any adverse side effects[605] and 10g has been used daily for 310 days in older adults (aged 57+/-11.1) with no significant differences from placebo.[519] Such a dose has also been demonstrated for long-term safety for people with Parkinson’s disease,[606] and at least one small retrospective study in athletes (surverying people taking creatine for up to or over a year) failed to find any significant differences in a battery of serum health parameters.[502] Other studies measuring serum parameters have also failed to find abnormalities outside the normal range.[607]
Total levels of testosterone in the body are 264 to 916 ng/dL in men age 19 to 39 years,[169] while mean testosterone levels in adult men have been reported as 630 ng/dL.[170] Levels of testosterone in men decline with age.[169] In women, mean levels of total testosterone have been reported to be 32.6 ng/dL.[171][172] In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.[171][172]
This suppression of creatine synthesis is thought to actually be beneficial, since creatine synthesis requires s-adenosyl methionine as a cofactor and may use up to 40-50% of SAMe for methylation[35][36][122] (initially thought to be above 70%, but this has since been re-evaluated[122]) though the expected preservation of SAMe may not occur with supplementation.[487] Reduced creatine synthesis, via preserving methyl groups and trimethylglycine (which would normally be used up to synthesize SAMe), is also thought to suppress homocysteine levels in serum,[37] but this may also not occur to a practical level following supplementation.[487]
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]
For many people in rehabilitation or with an acquired disability, such as following stroke or orthopaedic surgery, strength training for weak muscles is a key factor to optimise recovery.[35] For people with such a health condition, their strength training is likely to need to be designed by an appropriate health professional, such as a physiotherapist.
Three amino acids (glycine, arginine and methionine) and three enzymes (L-arginine:glycine amidinotransferase, guanidinoacetate methyltransferase and methionine adenosyltransferase) are required for creatine synthesis. The impact creatine synthesis has on glycine metabolism in adults is low, however the demand is more appreciable on the metabolism of arginine and methionine [11].
Testosterone is only one of many factors that influence aggression and the effects of previous experience and environmental stimuli have been found to correlate more strongly. A few studies indicate that the testosterone derivative estradiol (one form of estrogen) might play an important role in male aggression.[66][71][72][73] Studies have also found that testosterone facilitates aggression by modulating vasopressin receptors in the hypothalamus.[74]
Sally has a Bachelor's Degree in Biomedical Sciences (B.Sc.). She is a specialist in reviewing and summarising the latest findings across all areas of medicine covered in major, high-impact, world-leading international medical journals, international press conferences and bulletins from governmental agencies and regulatory bodies. At News-Medical, Sally generates daily news features, life science articles and interview coverage.
Few supplements have the solid scientific foundation that creatine has. Studies show that it's effective for 80 percent of those who use it. Since creatine is found naturally in meat, the more meat you eat, the less likely you'll need creatine supplementation. Vegetarians or those who rarely eat meat, however, can get huge boosts from most creatine supplements.
Stand lunge-length in front of a bench making sure your knee does not extend past your toes. Hold a dumbbell in each hand and rest the top of your left foot on the bench behind you. Lower your body until your rear knee nearly touches the floor and your front thigh is parallel to the floor. Then push through the heel of your front foot to return to standing, keeping the back foot on the bench. Repeat for required reps then switch legs.

Although creatine is a natural component of food, the amount of food required to supersaturate the muscle with PCr may not be feasible. For example, it could require 22 pounds of meat daily [8]. If creatine monohydrate is proven to be a safe and effective ergogenic aid, creatine supplementation may be the simplest way to increasing muscle stores. It may be beneficial to avoid caffeine if taking creatine supplements. One study showed that caffeine diminished strength gains seen with creatine use [9].
According to the two meta-analyses on the topic, creatine significantly increases power when supplemented in both sexes over a period of time up to 8 weeks, during which improvement over placebo is maintained, rather than being enhanced further. The rate at which power is derived from a resistance training regimen appears to be up to 78.5% greater with creatine relative to placebo, and in active trained men who are naive to creatine, this can be quantified at about 7kg for the bench press and 10kg for the squat over 8 weeks.
The largest amounts of testosterone (>95%) are produced by the testes in men,[2] while the adrenal glands account for most of the remainder. Testosterone is also synthesized in far smaller total quantities in women by the adrenal glands, thecal cells of the ovaries, and, during pregnancy, by the placenta.[130] In the testes, testosterone is produced by the Leydig cells.[131] The male generative glands also contain Sertoli cells, which require testosterone for spermatogenesis. Like most hormones, testosterone is supplied to target tissues in the blood where much of it is transported bound to a specific plasma protein, sex hormone-binding globulin (SHBG).
Testosterone is included in the World Health Organization's list of essential medicines, which are the most important medications needed in a basic health system.[111] It is available as a generic medication.[10] The price depends on the form of testosterone used.[112] It can be administered as a cream or transdermal patch that is applied to the skin, by injection into a muscle, as a tablet that is placed in the cheek, or by ingestion.[10]
But muscle can’t turn into fat, just like mud can’t turn into gold. If you quit lifting, your muscles mass will decrease over time because there’s no training to stimulate your body to keep it. And your body-fat level will increase if you don’t start eating less (since you burn less). The obvious solution when you stop lifting is to also stop eating so much.
Bodybuilders do cardio training such as running and using a StairMaster StepMill to burn fat and make their muscles more visible. “Do cardio throughout the year at least three days a week for at least 30-40 minutes, whether it be first thing in the morning on an empty stomach or after a post-workout protein shake,” says Heath. “Cardio won’t kill your gains as much as you think, you’ll see how much muscle you really have.” Break a sweat to stay lean ’round the clock.

In otherwise healthy adults subject to leg immobilization for two weeks while taking 20g creatine daily during immobilization and then 5g daily during eight weeks of rehabilitation, it was noted that the creatine group failed to reduce atrophy during the immobilization (10% reduction in cross sectional area and 22-25% reduction in force output) despite preventing a decrease in phosphocreatine, yet experienced a significantly enhanced rate of regrowth and power recovery.[358] A similarly structured and dosed study has also noted greater expression of skeletal muscle, GLUT4 expression, and a 12% increase in muscle phosphocreatine content.[330]

Recommended dose: The fastest way to increase muscle creatine stores is to follow the loading method of 20 grams per day for 5-7 days, followed by the standard maintenance dose of 5 grams per day. However, a lower dose of 5 grams for 28 days will also increase creatine stores without causing the 2-4 pound weight gain typically seen with a loading protocol.
For the best results, do the glute exercises and stretches listed below about three to four times per week. You can either aim for a specific number of reps (such as 10–20 reps per set, depending on your fitness level) or do the exercises in a circuit, performing each exercise for 45–60 seconds with a 15-second break between. For beginners, perform two sets or two rounds in total. And for advanced exercisers aim, for three to four sets/rounds in total.
Besides the high-quality protein content of casein/whey, the newer formulations have little or no lactose (i.e., milk sugar), which some people have negative reactions to. The native milk proteins also provide a host of smaller proteins called peptides, many of which, such as lactoferrin, have vital health benefits. The rich cysteine content of whey acts as a precursor of glutathione, a primary endogenous antioxidant and liver detoxifier in the body.
Due to this relative deficiency-state in vegetarians and vegans, some aspects of creatine supplementation are seen as more akin to normalizing a deficiency, rather than providing the benefits of supplementation. In young vegetarians, but not omnivores, creatine supplementation can enhance cognition.[60][61] The increased gain in lean mass may be more significant in vegetarians, relative to omnivores.[59] Supplementation of creatine in vegetarians appears to normalize the gap in storage between vegetarians and omnivores.[62] This is possibly related to a correlation seen in survey research, where vegetarianism and veganism appear to be more commonly affected by some mental disorders like anxiety and depression.[63]
1. Train each muscle group twice per week. To maximize muscle growth, plan to train every major muscle group at least twice per week. According to a 2016 Sports Medicine review, even if you don't work that muscle any harder or longer, by simply dividing your chest, leg or back workout into two days, you'll spur more muscle growth. While the jury is still out on whether training each muscle group three days per week is better than two at spurring hypertrophy, it is likely better suited toward experienced lifters than beginners, Matheny says.
In muscle cells, the creatine transporter is predominantly localized to the sarcolemmal membrane. Western blot analysis of creatine transporter expression revealed the presence of two distinc protein bands, migrating at 55kDa and 70kDa on reducing SDS-PAGE gels.[147][148] The 73kDa band has been reported to be the predominant band in humans, with no differences based on gender.[148] A more recent report demonstrated that the 55kDa creatine transporter variant is glycosylated, forming the 73 kDa protein. Therefore, the 55 and 75kDa protein bands are actually immature and mature/processed forms of the creatine transporter protein, respectively.[149]

There is a dirty little secret about testosterone cream that almost no one knows, and I’m going to share it here. Please don’t abuse it. If you take a vanishingly small dose of testosterone cream and apply it to your labia and the vulva (or your partner’s), you will witness a form of vasodilation rarely seen no matter how good you are in bed. It has a profound local effect and will produce a night you won’t forget for years.

When combined with an appropriate exercise program, dietary supplementation with β-hydroxy β-methylbutyrate (HMB) has been shown to dose-dependently augment gains in muscle hypertrophy (i.e., the size of a muscle),[38][39] muscle strength,[38][40][41] and lean body mass,[38][40][41] reduce exercise-induced skeletal muscle damage,[note 1][38][39][41] and expedite recovery from high-intensity exercise.[38][42] HMB is believed to produce these effects by increasing muscle protein synthesis and decreasing muscle protein breakdown by various mechanisms, including activation of the mechanistic target of rapamycin (mTOR) and inhibition of the proteasome in skeletal muscles.[40][43]


Bodybuilders often split their food intake for the day into 5 to 7 meals of roughly equal nutritional content and attempt to eat at regular intervals (e.g. every 2 to 3 hours). This method can serve two purposes: to limit overindulging in the cutting phase, and to physically allow for the consumption of large volumes of food during the bulking phase. Contrary to popular belief, eating more frequently does not increase basal metabolic rate when compared to the traditional 3 meals a day. While food does have a metabolic cost to digest, absorb, and store, called the thermic effect of food, it depends on the quantity and type of food, not how the food is spread across the meals of the day. Well-controlled studies using whole-body calorimetry and doubly labeled water have demonstrated that there is no metabolic advantage to eating more frequently.[38][39][40]


Why it made the list: Whey tops the list of mass-gain supplements because it's the most crucial for pushing protein synthesis. Whey is a milk protein that has a high level of branched-chain amino acids (BCAAs, No. 4 on our list). Bottom line: Whey takes the crown because it digests fast and gets to your muscles rapidly to start building muscle. Whey also contains peptides (small proteins) that increase blood flow to the muscles. This is why we always recommend consuming whey protein immediately after training.
It is hard to know how many men among us have TD, although data suggest that overall about 2.1% (about 2 men in every 100) may have TD. As few as 1% of younger men may have TD, while as many as 50% of men over 80 years old may have TD. People who study the condition often use different cut-off points for the numbers, so you may hear different numbers being stated.
Now that you've got the training part down, it's time to stretch it out. (Can you say ahhh?) Stretching while your muscles are warm can help improve your flexibility, says Davis, not to mention it just feels phenomenal after you've pushed yourself hard. A light cool-down is also great for calming the nervous system. While dynamic stretches should be your go-to during a warm-up, the cool-down is where static stretching comes in—this means holding a stretch for 20-30 seconds. These four passive stretches will do nicely.
She describes how to change oneAEs mindset, including psychology-related misconceptions about getting results, why itAEs important to not rush the process, and how to embrace sustainable methods, as well as accepting mistakes and being around supportive people; nutrition aspects, including the basics, guidelines, and moderation; movement patterns of strength training, as well as cardio and glute circuits; and building a better body and gauging and monitoring progress to become oneAEs own lifelong coach.
While many of the claims are based on scientifically based physiological or biochemical processes, their use in bodybuilding parlance is often heavily colored by bodybuilding lore and industry marketing and as such may deviate considerably from traditional scientific usages of the terms. In addition, ingredients listed have been found at times to be different from the contents. In 2015, Consumer Reports reported unsafe levels of arsenic, cadmium, lead and mercury in several of the protein powders that were tested.[7]

Finally, starvation (nutrient deprivation for four days) appears to increase activity of the creatine transporter secondary to decreasing serine phosphorylation (SGK target)[173] with no influence on tyrosine phosphorylation (c-Src target).[173] Starvation-induced increases in creatine influx do not necessarily mean more phosphocreatine, however, due to a depleted cellular energy state.[173]
I bought this for my husband since he recently started lifting again. I knew that he wanted to gain as much muscle mass as possible and this looked like a pretty good product. It comes in a nice black bottle with good labeling. The bottle contains 90 capsules, which is about a month and a half worth of supplements. He has been taking 2 capsules before bed each night and for the past few weeks and has had no negative side effects. It's also really easy to remember since you take the both at the same time instead of spread throughout the day. He says that he has noticed a difference most of all in his muscle tone and just an overall feeling of being refreshed.
Arginine mainly benefits the body in two ways. The first of these is by producing nitric oxide. When arginine enters the body, some of it gets converted into nitric oxide. Nitric oxide is important for regulating blood pressure, as it can enlarge the blood vessels. Larger blood vessels allow the body to increase blood flow throughout the body, bringing extra nutrients and oxygen to the muscles during exercise.
Creatine has been shown to influence androgen levels. Three weeks of creatine supplementation has been shown to increase dihydrotestosterone (DHT) levels, as well as the DHT:testosterone ratio with no effects on testosterone levels.[430] In contrast, creatine supplementation has been shown to increase testosterone levels when taken alongside a 10-week resistance training program.[431] A study in male amateur swimmers also noted that a creatine loading phase (20g daily for six days) was able to increase testosterone levels by around 15% relative to baseline.[397] 
Several review studies assessing the safety of creatine supplementation tend to make note of increases in formaldehyde and possible carcinogenic results.[451][452] Specifically, creatine is metabolized into an intermediate called methylamine, which can be converted to formaldehyde by the SSAO enzyme.[453] An increase in urinary formaldehyde has been noted in youth given 21g of creatine for one week, during which both methylamine (820% increase) and formaldehyde (350%) were increased, relative to control.[454] However, a more prolonged study using 300mg/kg (loading dose of around 20g) in adults for ten weeks failed to replicate these effects.[455]
“Reg Park’s theory was that first you have to build the mass and then chisel it down to get the quality; you work on your body the way a sculptor would work on a piece of clay or wood or steel. You rough it out””the more carefully, the more thoroughly, the better”” then you start to cut and define. You work it down gradually until it’s ready to be rubbed and polished. And that’s when you really know about the foundation. Then all the faults of poor early training stand out as hopeless, almost irreparable flaws. [..]
Parameters of lung function (main cause of death in ALS is declining respiratory function) have not benefited after creatine supplementation, and when quality of life is measured, there is no benefit either. Despite one study failing to find any significant differences in mortality risk, two other studies have suggested that creatine may reduce the risk. The results were nonsignificant, but due to all treatments being well tolerated it is thought that creatine may still play a role as an adjuvant.
You should be keeping whichever program you are doing to no more than 1 hour of duration. Be sure that you are focusing on keeping the intensity high rather than making the workout drag on. Plus, there's no research that says marathon training sessions are better for muscle growth. Focus on keeping your rest periods under a minute and limit the small talk with other gym members.
In your body, you can only store enough ATP for about 10 seconds of maximum exercise, this means that after those storages are depleted, it is up to your body to produce ATP to reach the demand your body is placing. [5] Creatine helps in the body by increasing stores of phosphocreatine which is the main ingredient used to create new ATP during intense exercise. By just supplementing creatine for 6 days, you can double your levels of creatine in your muscle storages, resulting in a higher capacity to create energy. [5]
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]

Escolar, D. M., Buyse, G., Henricson, E., Leshner, R., Florence, J., Mayhew, J., Tesi-Rocha, C., Gorni, K., Pasquali, L., Patel, K. M., McCarter, R., Huang, J., Mayhew, T., Bertorini, T., Carlo, J., Connolly, A. M., Clemens, P. R., Goemans, N., Iannaccone, S. T., Igarashi, M., Nevo, Y., Pestronk, A., Subramony, S. H., Vedanarayanan, V. V., and Wessel, H. CINRG randomized controlled trial of creatine and glutamine in Duchenne muscular dystrophy. Ann Neurol 2005;58(1):151-155. View abstract.
Cornelissen, V. A., Defoor, J. G., Stevens, A., Schepers, D., Hespel, P., Decramer, M., Mortelmans, L., Dobbels, F., Vanhaecke, J., Fagard, R. H., and Vanhees, L. Effect of creatine supplementation as a potential adjuvant therapy to exercise training in cardiac patients: a randomized controlled trial. Clin.Rehabil. 2010;24(11):988-999. View abstract.
Holding a kettlebell in your left hand, stand on your right foot and lift your left foot off the ground.. Keeping your weight in your midfoot to heel, inhale as you hinge at your hips and slightly bend your knee to push your butt backward. Keep your shin vertical and hips squared forward. Exhale as you drive through your heel to return to standing. Do 10-12 reps. Switch sides.
Objective: Are you getting stronger? Increasing either weight or reps? If you're measuring individual markers on a daily basis like vertical jump, grip strength, or resting heart rate then what sort of trends are you noticing in these variables? If they're staying the same while your strength is increasing, then you're recovering well. If they're decreasing and you find yourself weaker over time then you're not recovering well.

Some of these medications that can harm the kidneys include cyclosporine (Neoral, Sandimmune); aminoglycosides including amikacin (Amikin), gentamicin (Garamycin, Gentak, others), and tobramycin (Nebcin, others); nonsteroidal anti-inflammatory drugs (NSAIDs) including ibuprofen (Advil, Motrin, Nuprin, others), indomethacin (Indocin), naproxen (Aleve, Anaprox, Naprelan, Naprosyn), piroxicam (Feldene); and numerous others.
Jason Ferruggia is a highly sought after, world renowned strength & conditioning specialist and muscle building expert. Over the last 17 years he has personally trained more than 700 athletes from over 90 different NCAA, NFL, NHL and MLB organizations. He has also worked extensively with firefighters, police officers, military personnel, Hollywood stars and entertainers. Most importantly, Jason has helped over 53,000 skinny guys and hard gainers in 126 different countries build muscle and gain weight faster than they every thought possible.
If there are any benefits for swimming performance from creatine supplementation, they appear to be limited to a 50 meter sprint or a handful of 50 meter sprints with short intermissions. Excessive sprinting (over six sprints with short breaks) or too long of a break (five minutes rather than two) seem to not be associated with the benefits of creatine supplementation.
The muscle endurance objective is pursued when you want your muscles to be able to perform the same motions over an extended period of time or in other words when you want your muscles to be strong and not become tired rapidly. You'll want to use at least 4 sets from which at least 16 repetitions are performed. The muscle endurance objective is often used for muscles in your lower body, such as those located in your legs or your buttocks.
Creatine kinase enzymes (of which there are numerous isozymes) exist in both the mitochondria and the cytosol of the cell.[45][40] The four isozymes of creatine kinase include the Muscle Creatine Kinase (MCK), present in contractile muscle and cardiac muscle, and the Brain Creatine Kinase (BCK), expressed in neuron and glial cells and several other non-muscle cells. These two creatine kinases are met with Sarcolemmic Mitochondrial Creatine Kinase (sMitCK), expressed alongside MCK, and the ubiquitous Mitochondrial Creatine Kinase (uMitCK), which is expressed alongside BCK everywhere else.[25][39]
Back in the 1970s, scientists discovered that taking creatine in supplement form might enhance physical performance. In the 1990s, athletes started to catch on, and creatine became a popular sports supplement. The supplement is particularly popular among high school, college, and professional athletes, especially football and hockey players, wrestlers, and gymnasts. 
Weight training also provides functional benefits. Stronger muscles improve posture, provide better support for joints, and reduce the risk of injury from everyday activities. Older people who take up weight training can prevent some of the loss of muscle tissue that normally accompanies aging—and even regain some functional strength—and by doing so, become less frail.[33] They may be able to avoid some types of physical disability. Weight-bearing exercise also helps to prevent osteoporosis.[34] The benefits of weight training for older people have been confirmed by studies of people who began engaging in it even in their eighties and nineties.
Even if you have a schedule that allows for a 5-day workout split, many people (I’d even call it the majority) simply don’t have the recovery capacity needed to make that work. This could be due to genetics, age, injury history, various lifestyle factors (sleep, stress, etc.) and more. In these cases, better results would be seen with 3-4 workouts per week instead.
A simple blood test can determine testosterone levels. There is a wide range of “normal” or healthy level of testosterone circulating in the bloodstream. The normal range of testosterone for men is between 250 and 1100 ng/dL for adult males, and between 8 and 60 ng/dL for adult females, according to the Mayo Clinic. Ask your doctor to test your testosterone levels if you have concerns about low testosterone (low T).

Perhaps 1 to 2% of intramuscular creatine is degraded into creatinine each day, which is excreted in urine. Therefore, approximately 1 to 3 g of creatine needs replenishing daily to maintain basal levels. Some of this replacement is fulfilled by the liver and kidneys, which can use the amino acids arginine and glycine to synthesize creatine. A tiny minority of people has gene mutations that result in impaired creatine synthesis or transport. These unfortunate people experience severe neurodevelopmental problems beginning early in life and benefit from consuming more creatine in their diets.
A previous meta-analysis [28] reported an overall creatine supplementation effect size (ES) of 0.24 ± 0.02 for activities lasting ≤30 s. (primarily using the ATP- phosphocreatine energy system). For this short high-intensity exercise, creatine supplementation resulted in a 7.5 ± 0.7% increase from base line which was greater than the 4.3 ± 0.6% improvement observed for placebo groups. When looking at the individual selected measures for anaerobic performance the greatest effect of creatine supplementation was observed on the number of repetitions which showed an ES of 0.64 ± 0.18. Furthermore, an increase from base line of 45.4 ± 7.2% compared to 22.9 ± 7.3% for the placebo group was observed. The second greatest ES was on the weight lifted at 0.51 ± 0.16 with an increase from base line of 13.4 ± 2.7% for the placebo group and 24.7 ± 3.9% for the creatine group. Other measures improved by creatine with a mean ES greater than 0 were for the amount of work accomplished, weight lifted, time, force production, cycle ergometer revolutions/min and power. The possible effect of creatine supplementation on multiple high intensity short duration bouts (<30 s) have shown an ES not statistically significant from 0. This would indicate that creatine supplementation might be useful to attenuate fatigue symptoms over multiple bouts of high-intensity, short duration exercise. The ES of creatine on anaerobic endurance exercise (>30 – 150s), primarily using the anaerobic glycolysis energy system, was 0.19 ± 0.05 with an improvement from baseline of 4.9 ± 1.5 % for creatine and -2.0 ± 0.6% for the placebo. The specific aspects of anaerobic endurance performance improved by creatine supplementation were work and power, both of which had a mean ES greater than 0. From the findings of this previous meta-analysis [28] it would appear that creatine supplementation has the most pronounced effect on short duration (<30s) high intensity intermittent exercises.
Because the distribution of muscle strength is unique to each there is no short answer to this question. A personal trainer simply cannot tell all his/her customers to perform a bench press using 100 pounds because it will be too difficult for some and too easy for others. Rather the idea here is to use the right amount of weight that will make you successful in accomplishing the objective set previously (muscle power, strength or endurance).

Even human studies can be misinterpreted or manipulated. A few years ago a then-esoteric trace mineral called boron was found to increase testosterone, but only in older women, as it turned out. When boron was tested in young men engaged in weight training, it proved worthless for increasing testosterone. That doesn't mean boron is useless; it helps the body use the minerals calcium and magnesium, and it appears to increase mental alertness.
The rise in testosterone levels during competition predicted aggression in males but not in females.[90] Subjects who interacted with hand guns and an experimental game showed rise in testosterone and aggression.[91] Natural selection might have evolved males to be more sensitive to competitive and status challenge situations and that the interacting roles of testosterone are the essential ingredient for aggressive behaviour in these situations.[92] Testosterone produces aggression by activating subcortical areas in the brain, which may also be inhibited or suppressed by social norms or familial situations while still manifesting in diverse intensities and ways through thoughts, anger, verbal aggression, competition, dominance and physical violence.[93] Testosterone mediates attraction to cruel and violent cues in men by promoting extended viewing of violent stimuli.[94] Testosterone specific structural brain characteristic can predict aggressive behaviour in individuals.[95] 
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