Maughan RJ, King DS, Lea T. Dietary supplements. J Sports Sci. 2004 Jan;22(1):95-113.Kreider RB. Dietary supplements and the promotion of muscle growth with resistance exercise. Sports Med. 1999 Feb;27(2):97-110.Kerksick CM, Rasmussen CJ, Lancaster SL, et al. The effects of protein and amino acid supplementation on performance and training adaptations during ten weeks of resistance training. J Strength Cond Res. 2006 Aug;20(3):643-53.Update of Cochrane Database Syst Rev. 2001;(1):CD002946. Glucosamine therapy for treating osteoarthritis. Cochrane Database Syst Rev. 2005 Apr 18;(2):CD002946.AIS Sports Nutrition - AIS Sports Supplement Program 2007.

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.

Take time to rest. To give your muscles time to recover, rest one full day between exercising each specific muscle group. You might choose to work the major muscle groups at a single session two or three times a week, or plan daily sessions for specific muscle groups. For example, on Monday work your arms and shoulders, on Tuesday work your legs, and so on.
The reasons for differences in the effect of creatine on testosterone vs. DHT across studies are not clear, but also not mutually exclusive. A measured increase in DHT could indicate that testosterone levels were increased by creatine, but rapidly converted to DHT through a homeostatic mechanism. Differences in study subject populations, methodology, or the presence and type of concurrent exercise could also be contributing factors. At any rate, the literature collectively suggests that creatine has the general ability to cause a modest increase in androgen levels in men.
In isolated striatal cells (expressing creatine kinase), seven day incubation of 5mM creatine (maximal effective dose) appears to increase the density of GABAergic neurons and DARPP-32 (biomarker for spiny neurons[225]) with only a minor overall trend for all cells[226] and showed increased GABA uptake into these cells, as well as providing protection against oxygen and glucose deprivation.[226]
The general strategy adopted by most present-day competitive bodybuilders is to make muscle gains for most of the year (known as the "off-season") and, approximately 12–14 weeks from competition, lose a maximum of body fat (referred to as "cutting") while preserving as much muscular mass as possible. The bulking phase entails remaining in a net positive energy balance (calorie surplus). The amount of a surplus in which a person remains is based on the person's goals, as a bigger surplus and longer bulking phase will create more fat tissue. The surplus of calories relative to one's energy balance will ensure that muscles remain in a state of anabolism.
Kilduff, L. P., Georgiades, E., James, N., Minnion, R. H., Mitchell, M., Kingsmore, D., Hadjicharlambous, M., and Pitsiladis, Y. P. The effects of creatine supplementation on cardiovascular, metabolic, and thermoregulatory responses during exercise in the heat in endurance-trained humans. Int J Sport Nutr Exerc Metab 2004;14:443-460. View abstract.
Most experts recommend starting with your larger muscle groups and then proceeding to the smaller ones. The most demanding exercises are those performed by your large muscle groups, and you will need your smaller muscles to get the most out of these exercises. But don't feel limited by that. You can do your exercises in any order you like, and changing the order is a great way to challenge yourself in different ways.

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]
Some bodybuilders use drugs such as anabolic steroids and precursor substances such as prohormones to increase muscle hypertrophy. Anabolic steroids cause hypertrophy of both types (I and II) of muscle fibers, likely caused by an increased synthesis of muscle proteins. They also provoke undesired side effects including hepatotoxicity, gynecomastia, acne, the early onset of male pattern baldness and a decline in the body's own testosterone production, which can cause testicular atrophy.[42][43][44] Other performance-enhancing substances used by competitive bodybuilders include human growth hormone (HGH), which can cause acromegaly.
Negative regulators of the creatine transporter (CrT) are those that, when activated, reduce the activity of the CrT and overall creatine uptake into cells. As noted above, CrT activity is positively regulated by mTOR.[158] Consistent with the well-known role of AMPK as a suppressor mTOR signaling,[177] CrT activity has also been shown to be inhibited in response to AMPK activation in kidney epithelial cells.[178] Since AMPK suppresses mTOR via upstream TSC2 activation,[179] the negative regulation of AMPK on CrT activity in these cells appears to occur through an indirect mechanism. Although indirect, activation of AMPK has been noted to reduce the Vmax of the CrT without altering creatine binding, and is involved in internalizing the receptors.[178] This pathway seems to max out at around 30% suppression, with no combination of mTOR antagonists and AMPK inducers further suppressing creatine uptake.[178]

While most of these muscle building supplements can be taken at any time of the day, some are best to include in your pre-workout routine. Citrulline malate, in particular, is one that should be taken about an hour ahead of your workout. Because this supplement boosts performance, taking it ahead of your workout will maximize its effect, making sure you get the most out of the supplement.
Han:SPRD‐cy rats (human polycystic kidney disease model[514][515]) have pre-existing renal damage, which is accelerated upon ingestion of creatine supplementation at 0.3% of the diet for five days and 0.03-0.05% for the next 35 days (equivalent to human loading and maintenance).[516] During this particular disease state, renal water content and size progressively increases.[514][515] Since creatine supplementation furthered the increase by an additional 2.1%, it was thought that this property of creatine explained the 23% increased cyst scores seen relative to control.[516]
The specific mechanism of intestinal uptake for creatine is not clear, although transporters have been identified in rat jujenum, and confirmed at the mRNA level in humans.[129][130] The observation that creatine can be absorbed against a concentration gradient to a max ratio of 8:1 (8 times more creatine in the intestinal cell post absorption, relative to the lumen) supports transporter-mediated uptake, and the dependence on sodium and chloride implicate SLC6A8 (Creatine Transporter 1) as the operative transporter.[102]

In addition to the HIIT sessions, it’s always a good idea to go for a 30–60-minute walk as many days per week as you can. I recommend getting a minimum of 10,000 steps every day. Use a phone app to track them. If you’re into jogging, swimming, hiking, or some other form of long-duration, fairly low-intensity cardio, that is fine to do as well, and as often as you like.

You've got your equipment ready, now it's time to choose about eight to 10 exercises, which comes out to about one exercise per muscle group. Use the list below to choose at least one exercise per muscle group to start. For the larger muscles, like the chest, back, and legs, you can usually do more than one exercise. These involve a variety of equipment, so you can choose based on what you have available.

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]

Carducci, C., Birarelli, M., Leuzzi, V., Carducci, C., Battini, R., Cioni, G., and Antonozzi, I. Guanidinoacetate and creatine plus creatinine assessment in physiologic fluids: an effective diagnostic tool for the biochemical diagnosis of arginine:glycine amidinotransferase and guanidinoacetate methyltransferase deficiencies. Clin Chem 2002;48(10):1772-1778. View abstract.
Rheumatoid arthritis. Early research shows that taking creatine by mouth daily increases lean muscle mass and may improve muscle strength, but does not improve physical functioning in adults with rheumatoid arthritis. In children, taking a specific supplement containing creatine and fatty acids twice daily for 30 days might reduce pain and swelling. But the effects of creatine alone are not clear.
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).
That soreness you feel post-strength session may seem like a setback. Yet over time, you’ll come to acknowledge that it signifies you’re getting stronger. “You think, ‘I’ve done something worthwhile. My body is telling me I’ve had a workout.’ You look forward to the fatigue and interpret it in a positive way,” says John Spence, PhD, professor of physical education and recreation at the University of Alberta in Canada, who wrote a review on the effect of exercise on self-esteem. (Wondering how sore is too sore to work out? Here’s your answer.)

It can be hard to know where to start when beginning strength training. There are countless exercises you can do, some of which work some muscles, but not others. There are safety concerns to beware of, a wide variety of sometimes confusing equipment to help you in your efforts, and so on. With some familiarity of the basics of getting started with strength training, actually doing so can become far less daunting, and you can begin to craft a routine that is targeted toward helping you achieve your personal goals.