Put Up or Shut Up! How Effective is Caffeine for Gymrats, Self-Proclaimed Bodybuilders & Lifting Weights, in General?

Let's be honest: The authors exaggerate when they call the subjects 'bodybuilders'

Yes, there are dozens, no, I guess hundreds of studies investigating the effects of caffeine in (a) various groups of people (from the obese sedentary slob to the Olympian gold medallist) and (b) a vast range of contexts from the sit-to-stand test in the elderly to the effects of repeated caffeine consumption on high intensity performance (the results are interesting, by the way | learn more). What is surprisingly hard to find, however, are studies that deal with bodybuilding and caffeine which are not case reports of how some bro poisoned himself with an overdose of straight caffeine or caffeine-containing fat burners.
In this regard, a recent study by Hamid Arazi, Nazanin Dehlavinejad, and Roghayyeh Gholizadeh sticks out. Published late 2016 in the Turkish Journal of Kinesiology (Arazi. 2016), even though it is obviously not the only study evaluating the effects of caffeine or, and those studies are more frequent, the effects of caffeine + a plethora of other ingredients in kitchen-sink "pump" or "pre-workout" supplement in gymrats. Since a comparison of these results is (a) not necessary bodybuilding-specific and will yield conflicting results, the authors decided to conduct a

"[...] study aimed to investigate the acute effect of moderate amount of consumption of caffeine 6 mg per kg of body weight on maximal strength, repetition sustainability and training volume in the upper and lower body of novice bodybuilders" (Arazi. 2016).

Fifteen males' healthy gymrats - I guess eventually we have to admit that these "novice bodybuilders" are not Mr. Olympia, yet - who had resistance training between 6 months to a year participated voluntarily in this study.

Figure 1: Subject characteristics - note: while the study calls them "novice bodybuilders" (Arazi. 2016), we should be honest and admit that we are more or less talking about the average gymrat or "total beginner bodybuilder", here.

Subjects' characteristics are presented in Table 1. All were healthy non-smokers and did neither suffer from diseases nor consume products that would mess with the results of the study.
After 24h of caffeine abstinence, the subjects reported to the lab, where they ingested were randomized (double-blind method) to consume

• caffeine (gelatin capsules containing 6mg/kg) supplements or 
• placebo (maltodextrin) supplements,

each with 200 ml of water. To ensure that the caffeine levels would peak, the authors had their subjects wait an hour before the actual test was performed (that's somewhat debatable, because the athletes reported to the lab fasted, so that peak levels may have been reached earlier, but alas | learn more):

"Subjects performed special warm-up activities for 15 minutes. Then, they did one repetition maximum test (1RM) in bench press (as especial upper body exercise) and leg press (as original lower body exercise) with 3-minute rest intervals in the range of 3 to 5 attempts. After 5 minutes of rest, subjects carried out bench press and leg press 5 times with 80% of one repetition maximum with maximum possible repeat until exhaustion with 3 minutes' rest between sets" (Arazi. 2016). 

This testing procedure was repeated twice separated by an interval of one week and the analysis of the results is quite telling.This cannot be the only study on so-called "bodybuilders"! Well, if we are talking "caffeine, only," it is. There is yet an interesting paper on ephedrine + caffeine by Haghagi, et al. (Haghagi. 2014), which found that, in 12 male bodybuilders (mean age: 24.41±4.42 years, height: 174.83±3.61 cm and weight: 75.67±8.05 kg) training without a supplement (Con), Ephedrine ((E), 0.8 mg/kg); caffeine ((C), 6 mg/kg), a combination of E + C (0.8 mg/kg + 6 mg/kg), or placebo all yielded significant increases in lower body strength (P<0.05) and upper body endurance (P<0.05). Since the FT is not available online, I cannot tell you how large the inter-group differences were - with no differences being reported in the sloppily written abstract, they were presumably not sign., though.

Figure 1: Relative changes in strength and # reps to failure on bench and leg press w/ and w/out caffeine (Arazi. 2016).

As you can see in Figure 1, the t-test confirms that the subjects'bench press and leg press muscle strength significantly increased in the caffeine condition compared to placebo. Furthermore, all the depicted changes in strength and strength endurance (as evidenced by the increased repetition sustainability in the fourth and fifth set) reached statistical significance.

Table 2: Work volume from the first to the fifth (mean ± SD; *=sign. adv. for caffeine | Arazi. 2016)

It is thus not exactly surprising that the work volume was higher for the two last sets; that it was also higher for the initial sets (see Table 2), on the other hand, shows that the, seen as an average, not exactly impressive 4-6% strength increase is pronounced enough to allow for a significantly enhanced training volume, of which the latest reviews (e.g. Schoenfeld et al. 2016) show that it may, within certain limits, be the main determinant of your gains.
References:

• Arazi, Hamid, Nazanin Dehlavinejad, and Roghayyeh Gholizadeh. "The acute effect of caffeine supplementation on strength, repetition sustainability and work volume of novice bodybuilders." Turkish Journal of Kinesiology 2.3 (2016): 43-48.
• Astorino, T. A., et al. "Effect of acute caffeine ingestion on EPOC after intense resistance training." J Sports Med Phys Fitness 51.1 (2011): 11-7.
• Bangsbo, Jens, et al. "Acute and habitual caffeine ingestion and metabolic responses to steady-state exercise." Journal of Applied Physiology 72.4 (1992): 1297-1303.
• Duncan, Michael J., Mark Lyons, and Joanne Hankey. "Placebo effects of caffeine on short-term resistance exercise to failure." Int J Sports Phys Perf 4 (2009): 244-253.
• Fisher, S. M., et al. "Influence of caffeine on exercise performance in habitual caffeine users." International journal of sports medicine 7.05 (1986): 276-280.
• Goldstein, Erica, et al. "Caffeine enhances upper body strength in resistance-trained women." Journal of the International Society of Sports Nutrition 7.1 (2010): 1.
• Haghighi, Amirhosein, Kia Ali Heshmati, and Kakhak Seyed Alireza Hosseini. "The Effect Of Caffeine and Ephedrine Supplement and Their Combination on Maximal Strength and Muscular Endurance In Male Bodybuilders." (2014): 89-107.
• Hudson, Geoffrey M., et al. "Effects of caffeine and aspirin on light resistance training performance, perceived exertion, and pain perception." The Journal of Strength & Conditioning Research 22.6 (2008): 1950-1957.
• Schoenfeld, Brad J., Dan Ogborn, and James W. Krieger. "Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis." Journal of Sports Sciences (2016): 1-10.
• Sinclair, C. J. D., and J. D. Geiger. "Caffeine use in sports: a pharmacological review." Journal of Sports Medicine and Physical Fitness 40.1 (2000): 71.
• Tarnopolsky, Mark, and Cynthia Cupido. "Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumers." Journal of applied physiology 89.5 (2000): 1719-1724.