Testosterone is observed in most vertebrates. Testosterone and the classical nuclear androgen receptor first appeared in gnathostomes (jawed vertebrates). Agnathans (jawless vertebrates) such as lampreys do not produce testosterone but instead use androstenedione as a male sex hormone. Fish make a slightly different form called 11-ketotestosterone. Its counterpart in insects is ecdysone. The presence of these ubiquitous steroids in a wide range of animals suggest that sex hormones have an ancient evolutionary history.
^ Jump up to: a b Wallimann T, Wyss M, Brdiczka D, Nicolay K, Eppenberger HM (January 1992). "Intracellular compartmentation, structure and function of creatine kinase isoenzymes in tissues with high and fluctuating energy demands: the 'phosphocreatine circuit' for cellular energy homeostasis". The Biochemical Journal. 281 ( Pt 1) (Pt 1): 21–40. doi:10.1042/bj2810021. PMC 1130636. PMID 1731757.
Lie on your back with knees bent and feet flat on the floor. Lift your hips to come into a bridge position. Lift your left leg off the ground and extend it in front of you, keeping your pelvis level. Inhale as you slowly lower your hips toward the ground. Exhale as you drive your right heel into the ground and lift your hips. Do 10-12 reps. Switch sides.
Creatine pyruvate (also known as creatine 2-oxopropanoate) in an isomolar dose relative to creatine monohydrate has been shown to produce higher plasma levels of creatine (peak and AUC) with no discernible differences in absorption or excretion values. The same study noted increased performance from creatine pyruvate at low (4.4g creatine equivalence) doses relative to citrate and monohydrate, possibly due to the pyruvate group.
The doctor regularly measured my levels to be sure they were within the normal range for a male my age. In other words, I wasn’t taking ‘roids to get big; I was getting control of hormones that were not functioning well. This is how you should look at testosterone therapy – it is a gentle nudge to help you be in normal ranges, not a big push to get you huuu-yge. If you’re like me, you want “normal ranges” of a 27-year-old, not of a 60-year-old. It’s my plan to keep my testosterone where it is now (around 700) no matter what it takes. Right now, the Bulletproof Diet and the other biohacks I’ve written about do that! I’m 43.
Testicular diseases which may cause low T include inherited conditions such as undescended testis, Klinefelter’s syndrome, and acquired conditions such as Mump’s orchitis, trauma to the testicles, and damage caused by cancer treatment. Conditions which may affect the regulatory functions of the hypothalamus and pituitary gland include medications such as opioid pain medications and steroids, kidney failure, tumors, tuberculosis, sarcoidosis, HIV/AIDS, obesity, and physical or emotional stress.
All muscles of the legs are more likely to become overused when repetitive movements are performed; this can be one behavior tied to overtraining, especially without proper rest or when not enough stretching is performed between workouts. Injuries of the gluteus maximus are most commonly due to repetitive movements of the legs that require motion in only one direction or plane.
There are many potential reasons, but I am going to keep it simple and give you just two. The first and most common reason people suffer from underactive glutes or “glute amnesia” is due to lifestyle. Even when people train hard every day, if they spend the majority of the remainder of the day sitting down, then they are simply not using their glutes. And remember the old saying - if you don’t use it, you lose it. Unfortunately, this is just what happens with your glutes.
There is a nuclear receptor known as TIS1 (orphan receptor, since there are no known endogeouns targets at this time) which positively influences transcription of new creatine transporters and, in C2C12 myotubes, seems to be responsive to cAMP or adenyl cyclase stimulation from forskolin (from Coleus Forskohlii) with peak activation at 20µM.
Makes You Healthier: If you’re looking for a workout in which you get the biggest bang for your buck, strength training is it. Strength training increases bone density, builds a stronger heart, reduces your resting blood pressure, improves blood flow, halts muscle loss, helps control blood sugar, improves cholesterol levels, and improves your balance and coordination (turning you from this, to this).
In general, muscle content of creatine tends to be elevated to 15-20% above baseline (more than 20mM increase) in response to oral supplementation. People who get a sufficiently high influx of creatine are known as responders. A phenomena known as “creatine nonresponse” occurs when people have less than a 10mM influx of creatine into muscle after prolonged supplementation. Quasi-responders (10-20mM increase) also exist. Nonresponse is thought to explain instances where people do not benefit from creatine supplementation in trials, since some trials that find no significant effect do find one when only investigating people with high creatine responsiveness. There are clear differences between those who respond and those who do not, in regard to physical performance. People who are creatine responsive tend to be younger, have higher muscle mass and type II muscle fiber content, but this has no correlation with dietary protein intake.
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.
Cooke et al  observed positive effects of a prior (0.3 g/d kg BW) loading and a post maintenance protocol (0.1 g/d kg BW) to attenuate the loss of strength and muscle damage after an acute supramaximal (3 set x 10 rep with 120% 1RM) eccentric resistance training session in young males. The authors speculate that creatine ingestion prior to exercise may enhance calcium buffering capacity of the muscle and reduce calcium-activated proteases which in turn minimize sarcolemma and further influxes of calcium into the muscle. In addition creatine ingestion post exercise would enhance regenerative responses, favoring a more anabolic environment to avoid severe muscle damage and improve the recovery process. In addition, in vitro studies have demonstrated the antioxidant effects of creatine to remove superoxide anion radicals and peroxinitrite radicals . This antioxidant effect of creatine has been associated with the presence of Arginine in its molecule. Arginine is also a substrate for nitric oxide synthesis and can increase the production of nitric oxide which has higher vasodilatation properties, and acts as a free radical that modulates metabolism, contractibility and glucose uptake in skeletal muscle. Other amino acids contained in the creatine molecule such as glycine and methinine may be especially susceptible to free radical oxidation because of sulfhydryl groups . A more recent in vitro study showed that creatine exerts direct antioxidant activity via a scavenging mechanism in oxidatively injured cultured mammalian cells . In a recent in vivo study Rhaini et al  showed a positive effect of 7 days of creatine supplementation (4 x 5 g CM 20 g total) on 27 recreational resistance trained males to attenuate the oxidation of DNA and lipid peroxidation after a strenuous resistance training protocol.
^ Jump up to: a b c d Brosnan ME, Brosnan JT (August 2016). "The role of dietary creatine". Amino Acids. 48 (8): 1785–91. doi:10.1007/s00726-016-2188-1. PMID 26874700. The daily requirement of a 70-kg male for creatine is about 2 g; up to half of this may be obtained from a typical omnivorous diet, with the remainder being synthesized in the body ... More than 90% of the body’s creatine and phosphocreatine is present in muscle (Brosnan and Brosnan 2007), with some of the remainder being found in the brain (Braissant et al. 2011). ... Creatine synthesized in liver must be secreted into the bloodstream by an unknown mechanism (Da Silva et al. 2014a)
^ Jump up to: a b Lazaridis I, Charalampopoulos I, Alexaki VI, Avlonitis N, Pediaditakis I, Efstathopoulos P, Calogeropoulou T, Castanas E, Gravanis A (2011). "Neurosteroid dehydroepiandrosterone interacts with nerve growth factor (NGF) receptors, preventing neuronal apoptosis". PLoS Biol. 9 (4): e1001051. doi:10.1371/journal.pbio.1001051. PMC 3082517. PMID 21541365.