Increased Testosterone, Lower Cortisol Within 5-8 Days of Creatine Supplementation - Plus: Many Creatine Products Contain Creatinine & Other Impurities You Don't Want

Ok, I have to admit, eating, socializing, and sleeping may be more important, but I guess creatine monohydrate supplementation ranks 5th in the "things you got to do to get stronger and more muscular" algorithm ;-)

I know, acute hormonal changes in response to resistance training don't matter..., well at least as long as you compare one individual to another! If you take a look at intra-personal variations, a previous study I've written about at length here at the SuppVersity appears to indicate that there may be a link between the T-response to a workout and it's ability to promote muscle and strength gains (see goo.gl/T3sX1G). Be that as it may, the study at hand measured the resting testosterone concentrations which is why you can hardly argue that the following observation researchers from the University of Guilan in Iran made in their most recent study were not another convincing argument that anyone striving to build strength and size who passes on creatine supplementation must be an idiot.
The purpose of this study was to examine the effects of 3, 5 and 7 days of creatine loading coupled with resistance exercise on resting testosterone and cortisol concentrations, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate and rate pressure product (RPP).

Twenty physical active males volunteered with informed consent to participate in this study, which had been approved by the ethic committee of the Center of Sport and Health Sciences at the University. Volunteers were free from musculoskeletal injury and had not taken any dietary supple ment within the past 12 months. The volunteers were randomly assigned in a double-blind manner to

• a control or placebo group (Pl, n = 10; age 20 ± 1.1 y; weight 74.2 ± 4.8 kg; height 1.81 ± 0.07 m) where the subjects received a fake loading dose of 4x5g/day dextrose in pill form and 
• a creatine investigation group (Cr, n = 10; age 21.5 ± 1.1 y; weight 74.6 ± 4.2 kg; height 1.78 ± 0.08 m) where the subjects were given identically looking pills with 4x5g/day of creatine in them.

Volunteers were on their ordinary diet, not permitted to use nutritional supplementation, and did not consume anabolic steroids or any other anabolic agents known to increase performance.

Double Your Gains With Plain Creatine Monohydrate: Up to 2.6x Greater Strength Gains on the Bench With 5g of Plain Creatine Monohydrate per Day in Trained Rookies | read more

"One week prior to initiation of study, each participant was familiarized with the testing and resistance exercise pro cedures. Researchers clearly explained the purpose and procedures of the study to the participants who volunteered for the study. During this session, age (yr), height (m) and weight (kg) were determined. One week later, each par ticipant was required to attend the laboratory on eight separate occasions, with the first visit for measurement of blood pressure and heart rate, testosterone and cortisol con centrations, respectively, and then six visits for completion of the main experimental conditions; 3 sessions resistance exercises (day 3, 5 and 7) and 3 sessions testing (day 4, 6 and 8).

At the first visit, all participants given 4 × 5 g.d−1 dose of creatine or dextrose and maintained for seven days. All testing or exercise sessions began after approximately 12 hours overnight fast and 8 hours sleep. The temperature the laboratory was maintained at 21 C°."

During the seven days supplementation period, participants were prescribed a 4 × 5 g.d−1 dose of dextrose (placebo; Pl) or creatine (Cr) (Creatine Fuel, Twin Laboratories, Inc., Hauppauge, NY). Each supplement was measured using elec tronically calibrated scales and placed in identical coded airtight bags. Participants were instructed to consume the supplements, dissolved in approximately 300 mL of grape juice for better dissolution of creatine and ingested the solution with morning, mid-day, afternoon, and before sleep. Self-reported compliance to supplementation across the group was 100%. All participants were encouraged to adhere to their normal and similar dietary patterns through out the study. Volunteers were also asked to maintain their normal level of daily activity during the investigation.
Under the direction of professional fitness instructors, all resistance exercise sessions took placed in a weight training room. Participants performed resistance exercises at day 3, 5, and 7. During each session, subjects performed 3 × 10-rep of 9 exercises that included: Bench press, shoulder press, lat-pull down, arm curl, squats, leg press, leg extension, leg curl, and abdominal crunches. The intensity of program was determined at 75 or 85% of one repetition maximum. A minute break between sets of exercise was allowed for rest. The subjects were not allowed to increase the lifting load during exercises.

Figure 1: Relative changes in testosterone and cortisol at rest vs. baseline (Arazi. 2015).

As the data in Figure 1 tells you, the combined resistance training + supplementation regimen lead to significant changes in resting testosterone and cortisol concentrations from baseline to 5 and 7 days
supplementation in Cr group (P < 0.05). In addition, Cr group had significant higher resting testosterone concentration compared to Pl group after 5 and 7 days of creatine loading (P < 0.05).

As it was to be expected creatine did not lead to unwanted increases in systolic or diastolic blood pressure , mess with the heart rate, mean arterial pressure or rate pressure product as some fearmonegerish laypress articles would have it.
References:

• Arazi, H., et al. "Effects of short term creatine supplementation and resistance exercises on resting hormonal and cardiovascular responses." Science & Sports (2015).
• Hall, Matthew, and Thomas H. Trojian. "Creatine supplementation." Current sports medicine reports 12.4 (2013): 240-244.
• MacLaren, Don. "Chapter 18-Supplements for high intensity exercise: Creatine and other ergogenic aids: Chapter taken from Drugs in Sport ISBN: 978-0-203-87382-3." Routledge Online Studies on the Olympic and Paralympic Games 1.43 (2012): 247-261.
• Moret, Sabrina, Annalisa Prevarin, and Franco Tubaro. "Levels of creatine, organic contaminants and heavy metals in creatine dietary supplements." Food Chemistry 126.3 (2011): 1232-1238.
• Rawson, Eric S., et al. "Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain." Nutrition 27.4 (2011): 451-455.