These terms combine the prefix iso- (meaning "same") with tonic ("strength") and plio- ("more") with metric ("distance"). In "isotonic" exercises the force applied to the muscle does not change (while the length of the muscle decreases or increases) while in "plyometric" exercises the length of the muscle stretches and contracts rapidly to increase the power output of a muscle.
Testosterone levels generally peak during adolescence and early adulthood. As you get older, your testosterone level gradually declines — typically about 1 percent a year after age 30 or 40. It is important to determine in older men if a low testosterone level is simply due to the decline of normal aging or if it is due to a disease (hypogonadism).
Whenever you hear the word, “bodybuilding”, your mind usually flashes you images of bulging muscles, steel, sweat, the shouts of weightlifters, and ripped, muscular bodies of men and women in skimpy spandex. Your mind instantly takes you to the gym followed by wishful thinking that you can have a sexy body and bigger muscles. However, it takes more than just
The largest determiner of your metabolic rate is actually your total body mass. “The more cells, even fat cells, in your body, the more furnaces you have burning at any given time,” Dr. Church says. Think of it this way: It takes more juice to charge your tablet than it does to charge your phone. People who are taller and have a larger bone structure, therefore, will have a higher BMR than people who are shorter and have a slimmer build. While you can control your body mass to some extent by gaining or losing weight, you can’t change your height or your bone structure. All in all, most of a person’s BMR is determined by genetic factors, Dr. Church says.
In people whose kidneys don’t function optimally, supplemental creatine seems to be safe, too.[513][518][313][528] However, studies in people with suboptimal kidney function are fewer than in healthy people, and they are short-term. People with kidney dysfunction, or at risk for developing kidney dysfunction (e.g., people with diabetes, high blood pressure, or family history of kidney disease; people over sixty; and non-Hispanic blacks), might wish to forgo creatine, or otherwise take only the lowest effective dose (3 g/day)[527] after talking to their doctor.
If you’re a beginner, you should train with three full-body workouts per week. In each one, do a compound pushing movement (like a bench press), a compound pulling movement (like a chinup), and a compound lower-body exercise (squat, trap-bar deadlift, for example). If you want to add in 1–2 other exercises like loaded carries or kettlebell swings as a finisher, that’s fine, but three exercises is enough to work the whole body.
This is why I never understand why girls who don’t want to “get bulky” are told by trainers to do 3 sets of 10-12 (or 5 sets of 1,000 reps of bicep curls with a 1 lb pink dumbbell). While it’s difficult for women to gain any sort of size lifting in ANY rep range, if we were trying to gain muscle size, that’s EXACTLY what we would want to do (as it would be causing sarcoplasmic hypertrophy).
Testosterone is the primary sex hormone in men, and it is responsible for the development of many of the physical characteristics that are considered typically male. Women also produce the hormone in much smaller amounts. Testosterone, part of a hormone class known as androgens, is produced by the testicles after stimulation by the pituitary gland, which is located near the base of the brain, and it sends signals to a male's testicles (or to a woman's ovaries) that spark feelings of sexual desire. (1)
Testosterone may prove to be an effective treatment in female sexual arousal disorders,[52] and is available as a dermal patch. There is no FDA approved androgen preparation for the treatment of androgen insufficiency; however, it has been used off-label to treat low libido and sexual dysfunction in older women. Testosterone may be a treatment for postmenopausal women as long as they are effectively estrogenized.[52]
So, for example, with the moves above you'd do 15 squats followed by 15 push-ups. Take a little breather then repeat that two more times. Then you move on to your walking lunges and lat pull-downs (and repeat those three times total, too). You can really do anywhere from eight reps to 15 (and even just two sets, if you don't have time for three), but "it’s not a bad idea for beginners to start with a 15-rep range to get comfortable with the exercises," says Davis. And while there's some debate over whether three sets of an exercise is really best, "it’s a great beginner model," says Davis. Don't overcomplicate things when you're just getting started.
The maximum amount of creatine the body can store is about 0.3 gram per kilogram of body weight [6]. The creatine content of skeletal (voluntary) muscles averages 125 millimoles per kilogram of dry matter (mmol/kg/dm) and ranges from about 60 to 160 mmol/kg/dm. Approximately 60% of muscle creatine is in the form of PCr. Human muscle seems to have an upper limit of creatine storage of 150 to 160 mmol/kg/dm. Athletes with high creatine stores don't appear to benefit from supplementation, whereas individuals with the lowest levels, such as vegetarians, have the most pronounced increases following supplementation. Without supplementation, the body can replenish muscle creatine at the rate of about 2 g/day [7].
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.
How much weight? Start with a pair of light dumbbell hand weights (2 to 3 pounds for women and 5 to 8 pounds for men). If you can’t do 12 repetitions (or reps are the number of times you do the exercise) the weight is too heavy. If your muscles don’t feel tired after 12 reps, it’s too light. Adjustable weights that can be strapped to wrists or ankles may be convenient if you have arthritis in your hands. You can also use home or gym weight machines, or resistance bands.
When endothelial cells have a higher creatine concentration, they appear to be mildly less permeable when incubated with 0.5-5mM creatine, while the higher concentration (5mM) is able to fully ablate TNF-α-induced neutrophil adhesion and both E-selectin and ICAM-1 expression.[316] This effect was prevented with ZM241385, an A2A (adenosine) receptor antagonist,[316] and since adenosine released by this receptor is known to be protective of endothelial cells,[317][318] it is thought that creatine works vicariously through this receptor and adenosine release, thought to be due to releasing ATP (occurs in response to stress[319][320]) which protects the cell via the A2A signaling system.[316]
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.
You've figured out the exercises you should be doing, but what about the number of sets and repetitions? Your decision should be based on your goals. The American College of Sports Medicine recommends 4 to 6 reps for strength and hypertrophy, 8 to 12 reps for muscular strength and 10 to 15 reps for muscular endurance. They also recommend at least one set of each exercise to fatigue although you'll find that most people perform about 2 to 3 sets of each exercise. In general:

It was later noted that creatine was able to nonsignificantly augment various proinflammatory cytokines (CCL2, iNOS, ICAM-1, TGF-β, TIMP-1) and the presence of eosinophils in lung tissue, as well as to per se cause lung infiltration of these immune cells without requiring the presence of the allergen.[442] Neutrophils and macrophages were unaffected,[442] reflecting the past study of no influence on macrophages,[440] but the only instance where creatine appeared to either significantly add to ovalbumin or to per se induce statistically significant increases were in IL-5 secretion and goblet cell infiltration, although VCAM-1 expression was close. While creatine per se increased nF-κB activity, it suppressed the ovalbumin-induced increase.[442]

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.

Different forms of creatine in combination with other sports supplements as well as varying doses and supplementation methodology should continue to be researched in an attempt to understand further application of creatine to increase sports and exercise performance of varying disciplines. It is important to remain impartial when evaluating the safety of creatine ingested as a natural supplement. The available evidence indicates that creatine consumption is safe. This perception of safety cannot be guaranteed especially that of the long term safety of creatine supplementation and the various forms of creatine which are administered to different populations (athletes, sedentary, patient, active, young or elderly) throughout the globe.

How to do it: Use just your bodyweight, dumbbells, or a resistance band around the top of your knee to activate your glute medius, Reames says. Assume the same setup of a basic squat, feet shoulder-width apart and knees neutral. Squat down, knees bent at 90° angles, and step to the side. Continue repeating this side-step motion down and return to your starting position. 
Researchers described the study as one of the first to examine how strength training can reduce the risk of cardiovascular disease, separate from the effects of aerobic activity like running or long walks. The point: for those who are not meeting recommended guidelines for aerobic activity—perhaps because they lack the time—bursts of weight training can be enough.
Having a strong butt will get you far—literally. Our glutes are responsible for powering us through everything from long runs to tough strength workouts to a simple jaunt up a flight of stairs. Strong glutes that can take on the brunt of the work can help us avoid overcompensating with smaller muscles during lower-body exercises. Plus, beyond just helping us move, the glutes play an important role in "stabilizing our entire lumbo-pelvic-hip complex," says Cori Lefkowith, NASM-certified personal trainer and owner of Redefining Strength in Costa Mesa, California. That translates to better form, more efficient movement, and a reduced risk of straining your lower back and hips.
If you touch your phone between exercise sets, it better be to set its timer to 30 to 90 seconds. When lifting for hypertrophy, rest periods of 30 to 90 seconds encourage a quick release in muscle-building hormones (including testosterone and human growth hormone) while also making sure that you really, truly fatigue your muscles, according to Fitzgerald.
Another supplement that’s ideal to take pre-workout is protein. Depending on your goals and your workout time, taking protein before your workout can help you keep your energy levels elevated while working out. Make sure you give yourself at least an hour between the time you take your protein and your workout time so that your body has time to digest.
When lifting to complete fatigue, it takes an average of two to five minutes for your muscles to rest for the next set. When using lighter weight and more repetitions, it takes between 30 seconds and a minute for your muscles to rest. For beginners, working to fatigue isn't necessary, and starting out too strong can lead to too much post-exercise soreness.
Creatine supplementation in the under 18 population has not received a great deal of attention, especially in regards to sports/exercise performance. Despite this, creatine is being supplemented in young, <18 years old, athletes [52,53]. In a 2001 report [52] conducted on pupils from middle and high school (aged 10 – 18) in Westchester County (USA) 62 of the 1103 pupils surveyed were using creatine. The authors found this concerning for 2 main reasons: firstly, the safety of creatine supplementation is not established for this age group and is therefore not recommended. Secondly, it was speculated that taking creatine would lead on to more dangerous performance enhancing products such as anabolic steroids. It is important to point out that this potential escalation is speculation. Furthermore, a questionnaire was used to determine creatine use amongst this age group and does not necessarily reflect the truth.
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.
Low back pain — The glutes help the body properly perform multiplanar movements that can stress the back, such as bending over or squatting down. By helping the torso, pelvis, hips and legs remain evenly balanced and stable, the body can move in dynamic ways without over-straining or rounding one specific area of the spine due to the pull of gravity. (5)
Creatine also speeds recovery from exercise, enhancing adaptations such as strength and skeletal muscle hypertrophy. This has repeatedly been shown in teenagers, young adults, and the elderly alike. Accelerated recovery not only results from enhanced ATP restoration, for creatine also bolsters repletion of muscle carbohydrate stores, which may be related to protection against exercise-induced muscle damage. Such effects are especially germane to people undergoing short-term periods in which exercise training loads are substantially increased (“overreaching”). 

Over time, we naturally lose muscle mass in a process called sarcopenia. On average, men lose about 30% of their muscle mass during their lives. Usually, this begins in your 30s and progresses slowly as you age. But, don’t despair. You can rebuild and maintain muscle mass even as you age. Often, diet and exercise are enough. But, sometimes, if the above hormones play a role, your doctor may recommend medications and additional treatments (4).

Brain injury. Early research shows that taking creatine by mouth daily for 7 days increases the ability to exercise by increasing lung function in people with a spinal cord injury. However, other research shows that creatine does not improve wrist muscle or hand function. Early research also shows that taking creatine by mouth daily for 6 months reduces amnesia following a traumatic brain injury in children.

How much weight? Start with a pair of light dumbbell hand weights (2 to 3 pounds for women and 5 to 8 pounds for men). If you can’t do 12 repetitions (or reps are the number of times you do the exercise) the weight is too heavy. If your muscles don’t feel tired after 12 reps, it’s too light. Adjustable weights that can be strapped to wrists or ankles may be convenient if you have arthritis in your hands. You can also use home or gym weight machines, or resistance bands.