Similarly to complex training, contrast loading relies upon the enhanced activation of the nervous system and increased muscle fibre recruitment from the heavy set, to allow the lighter set to be performed more powerfully. Such a physiological effect is commonly referred to as post-activation potentiation, or the PAP effect. Contrast loading can effectively demonstrate the PAP effect: if a light weight is lifted, and then a heavy weight is lifted, and then the same light weight is lifted again, then the light weight will feel lighter the second time it has been lifted. This is due to the enhanced PAP effect which occurs as a result of the heavy lift being utilised in the subsequent lighter lift; thus making the weight feel lighter and allowing the lift to be performed more powerfully.
At the end of the day, yes, strength training does impact your metabolism, but any boost you get will be minimal and completely secondary to all of the other health benefits of strength training. Any change in metabolism or increase in calorie burn will vary widely from person to person, and depends on so many factors: your genetics, eating habits, health conditions, what workout you do that day, how much sleep you’re getting, and even how stressed you are on any given day. But incorporating a couple of strength training sessions into your fitness routine is worth doing no matter what—you’ll feel yourself get stronger, and put yourself in a position to say healthier throughout life. Those are the best, most promising benefits to work for.
Some of these athletes take it to an unhealthy — and in some cases illegal — extreme with anabolic steroids, prohormones, diuretics, and potentially harmful substances. In addition to their potential performance-enhancing attributes, many of these substances also can have serious and significant side effects. A telling example of this is the story of ephedra — a once widely-used supplement for bodybuilding that has since been banned and removed from the market due to multiple reports of life-threatening side effects and death after its use.
While testosterone stimulates a man’s sex drive, it also aids in achieving and maintaining an erection. Testosterone alone doesn’t cause an erection, but it stimulates receptors in the brain to produce nitric oxide. Nitric oxide is a molecule that helps trigger a series of chemical reactions necessary for an erection to occur. When testosterone levels are too low, a man may have difficulty achieving an erection prior to sex or having spontaneous erections (for example, during sleep).
He pointed to data sets in Mayo Clinic Proceedings that found resistance training reduced the risk of developing metabolic syndrome or hypercholesterolemia. “If you build muscle, even if you’re not aerobically active, you burn more energy because you have more muscle. This also helps prevent obesity and provide long-term benefits on various health outcomes.”
Creatine kinase enzymes (of which there are numerous isozymes) exist in both the mitochondria and the cytosol of the cell. 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.
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.
Although muscle stimulation occurs in the gym (or home gym) when lifting weights, muscle growth occurs afterward during rest periods. Without adequate rest and sleep (6 to 8 hours), muscles do not have an opportunity to recover and grow. Additionally, many athletes find that a daytime nap further increases their body's ability to recover from training and build muscles. Some bodybuilders add a massage at the end of each workout to their routine as a method of recovering.
In addition to improving athletic performance and muscle strength, creatine is taken by mouth for creatine deficiency syndromes that affect the brain, aging, bone density, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), depression, diabetes, exercise tolerance, fibromyalgia, Huntington's disease, disease that cause inflammation in the muscles (idiopathic inflammatory myopathies), Parkinson's disease, diseases of the muscles and nerves, multiple sclerosis, muscle atrophy, muscle cramps, breathing problems in infants while sleeping, head trauma, Rett syndrome, an eye disease called gyrate atrophy, inherited disorders that affect the senses and movement, schizophrenia, muscle breakdown in the spine, and recovery from surgery. It is also taken by mouth to slow the worsening of amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), osteoarthritis, rheumatoid arthritis, McArdle's disease, and for various muscular dystrophies.
The gluteus maximus arises from the posterior gluteal line of the inner upper ilium, and the rough portion of bone including the crest, immediately above and behind it; from the posterior surface of the lower part of the sacrum and the side of the coccyx; from the aponeurosis of the erector spinae (lumbodorsal fascia), the sacrotuberous ligament, and the fascia covering the gluteus medius. The fibers are directed obliquely downward and lateralward; The muscle has two insertions: Those forming the upper and larger portion of the muscle, together with the superficial fibers of the lower portion, end in a thick tendinous lamina, which passes across the greater trochanter, and inserts into the iliotibial band of the fascia lata; and the deeper fibers of the lower portion of the muscle are inserted into the gluteal tuberosity between the vastus lateralis and adductor magnus. Its action is to extend and to laterally rotate the hip, and also to extend the trunk.
Focus on form. Good form means you can reap all of the benefits of your workout and avoid injuries at the same time. To maintain proper form, pay attention to your posture (stand tall with chest lifted and abs held tight), move slowly (this ensures you're relying on muscles, not momentum, to do the lifting), and remember to breathe. Many people hold their breath while exerting, but exhaling during the hardest part of the exercise helps fuel the movement.