Ingestion of 400mg Caffeine Before a Workout Can Prevent Delayed Onset Muscle Soreness in Resistance Trained Men

Too many side-laterals without coffee?

Still having DOMS despite Alex Leaf's article on "DOMS - Delayed Onset Muscle Soreness: What Is DOMS & How Can It Be Managed? Science, Strategies, Supplements" (read more)?

In that case you are probably not a great fan of pre-workout products, coffee or energy drinks, because if you were, it is not unlikely that you had - instinctively, if you will - done everything right by consuming a hefty dose of the world's #1 OTC drug, caffeine, before each of your workouts.

400mg is plenty, but it does the trick

In case you have no clue what I am talking about, I'd suggest you take a look at the results of a recent paper by Hurley, Hatfield, and Riebe in the Journal of Strength and Conditioning Research (Hurley. 2013). In a series of tests that involved a strenuous biceps workout 4 sets of 10 bicep curls on a preacher bench, followed by a fifth set in which subjects completed as many repetitions as possible. The workout that was performed twice, with a one-week "wash-out" period - once with and once without the ingestion of 5mg/kg of caffeine 1h before the training session.

When the scientists compared the performance, perceived exertion and post-workout muscle soreness parameters they found that the ingestion of 5mg/kg caffeine ...

• had a beneficial effects on the perception of muscle soreness, 
• reduced the levels of perceived exertion, and
• lead to significant increases in performance

As you can see in Figure 1 the equivalent of ~2-3 cups of coffee did nut just ameliorate the pain on day 2 after the workout (that's usually when DOMS hits you hard). It did also speed up the "regeneration", or rather the reduction of pain.

Figure 1: Soreness values expressed relative to baseline testing (left) CK levels after the training session and number of repetitions on the all-out set (right; Hurley. 2013)

I have to admit, I was tempted to write that caffeine sped up the recovery process, but if you read part II of Alex' two-part series on DOMS, you will be aware that it is not warranted to use DOMS as a marker of regeneration ("DOMS - Delayed Onset Muscle Soreness: No Pain, No Gain? Is DOMS Necessary to Build Muscle?" | learn more).
The non-existent effects on the creatine kinase (CK) levels of the the 12 healthy resistance-trained men (age 18–25 years) supports Alex' assessment that the link between CK and DOMS is a temporary one: While the peak values of DOMS and CK occur at the same time, a high CK level does neither predict a high degree of delayed onset muscle soreness, nor vice versa.

So what's the mechanism here

In view of the fact that the continuous provision of caffeine throughout the recovery phase did not lead to similar / increased reduction in DOMS, it appears certain that the effects of caffeine are acute. This means it works only, if it is ingested 1h before the workout and will thus achieve it's peak value when you are actually working out (depending on the dosage and delivery method, the caffeine levels peak after 40-60 min).

As Hurley et al. point out, the effect could be brought about by a partial blockade of the natural increase in muscular adenosine concentrations that have been observed to increase in the working muscle and blood after high-intensity exercise in previous studies (Tarnopolsky, 2000; Davis. 2003; Motl. 2006). It would also stand in line with the (unsurprising) observation that the subjects’ perceived exertion was significantly lower with caffeine in the final 3 sets of exercise - an effect that has also been attributed to the adenosine-inhibiting effects of caffeine (Davis. 2003):

"This response is attributed to the role of caffeine as a CNS stimulant and inhibiting adenosine receptor activity. Caffeine stimulates the CNS by secreting serotonin into the cerebral cortex, which results in mood improvements, increased mental awareness, and decreased fatigue and tiredness. This is all a result of inhibited adenosine activity thus reducing perception of pain, which could increase ability to perform more repetitions." (Hurley. 2013)

In view of the fact that the adenosine levels have not been accessed, the authors are eventually still stuck for an answer with respect to the exact underlying mechanism of the anti-DOMS effects of caffeine. Adenosine is a likely candidate, though, and before I would do a follow up study on this, I would rather take some money to find out whether 400mg of caffeine taken before a PM workout won't be doing more harm than good by having profound negative effect on your sleep quality.
References:

• Astorino TA, Rohmann RL, Firth K, Kelly S. Caffeine-induced changes in cardiovascular function during resistance training. Int J Sport Nutr Exerc Metab. 2007 Oct;17(5):468-77.
• Davis JM, Zhao Z, Stock HS, Mehl KA, Buggy J, Hand GA. Central nervous system effects of caffeine and adenosine on fatigue. Am J Physiol Regul Integr Comp Physiol. 2003 Feb;284(2):R399-404. Epub 2002 Oct 24.
• Hurley CF, Hatfield DL, Riebe DA. The effect of caffeine ingestion on delayed onset muscle soreness. J Strength Cond Res. 2013 Nov;27(11):3101-9.
• Motl RW, O'connor PJ, Tubandt L, Puetz T, Ely MR. Effect of caffeine on leg muscle pain during cycling exercise among females. Med Sci Sports Exerc. 2006 Mar;38(3):598-604.
• Tarnopolsky M, Cupido C. Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumers. J Appl Physiol (1985). 2000 Nov;89(5):1719-24.