Caffeinated Curiosity Part Three: Caffeine vs. Coffee ~ The Battle of the Heavyweights
As we have previously eluded to, you can ingest caffeine from a variety of dietary sources, the most prevalent of which being coffee. But will they all result in the same ergogenic effect?
Interestingly few studies, however, have shown a positive effect of coffee on exercise performance.
Coffee has been documented to improve performance in some (Costill et al, 1978; Wiles et al, 1992; McLellan & Bell, 2004), but not all studies (Graham et al, 1998; Butts, 1985) – This may seem surprising as reports have shown that coffee is the most concentrated dietary source of caffeine, as well as being one of the largest sources of caffeine used by athletes prior to competition (Desbrow & Leveritt, 2006).
Amongst the current studies, only two investigations have actually used coffee rather than decaffeinated coffee plus anhydrous caffeine (McLellan & Bell, 2004; Graham et al, 1998), with only one of these studies showing an ergogenic effect of coffee (McLellan & Bell, 2004) – further identifying the variable evidence surrounding the performance enhancing effects of coffee. Work by Graham et al (1998), supports the aforementioned variability, documenting that running time to exhaustion (85% VO2 max) was only improved when runners ingested pure caffeine (4.5 mg CAF/kg BW), prior to exercise, but not when they ingested either regular coffee (4.5 mg CAF/kg BW), decaffeinated coffee plus caffeine (4.5 mg CAF/kg BW), decaffeinated coffee and a placebo control.
Graham and colleagues (1998) suggested that other components in coffee known as chlorogenic acids might have antagonised the physiological responses of caffeine. However, chlorogenic acids in the coffee or in the plasma were not measured in their study.
Chlorogenic acids are a group of phenolic compounds that possess a quinic acid ester of hydroxycinnamic acid (Desbrow & Leveritt, 2006). The consumption of chlorogenic acids varies significantly in coffee ranging from 20-675 mg per serving (Desbrow & Leveritt, 2006). It has previously been shown in vitro that chlorogenic acids antagonize adenosine receptor binding of caffeine (de Paulis et al, 2002) and cause blunting to heart rate, blood pressure and cause a dose-dependent relaxation of smooth muscle (Tse, 1992).
It is still unclear what role chlorogenic acids have on the physiologic and metabolic effects of coffee and caffeine during exercise in humans, partly due to the large variation of chlorogenic acids concentrations between coffee beverages.
Recent work by Hodgson et al (2013) set out to investigate whether the acute intake of coffee (5 mg CAF/kg BW) and anhydrous caffeine (5 mg CAF/kg BW) were ergogenic to cycling performance when compared to decaffeinated coffee or placebo beverages, using a validated 45-minute time trial performance test. In addition, participants completed a steady state exercise bout prior to the time trial, providing an opportunity to also investigate the effect of acute anhydrous caffeine or coffee intake on substrate oxidation and plasma metabolite responses. Hodgson et al (2013), interestingly, showed that coffee improved performance to the same extent as caffeine when compared to decaf coffee and placebo; 4.7% and 4.3% respectively, becoming the first study to date to demonstrate that coffee consumed 1 h prior to exercise, at a high caffeine dose (5 mg CAF/kg BW), is equally as effective as caffeine at improving endurance exercise performance.
Differences in methodological protocols between Graham et al (1998) and Hodgson et al (2013) may account for the differential effects of stimulatory beverages. Time to exhaustion tests have been shown to be highly variable from day to day, with large coefficient of variations (CV) documented; it is possible that this large variability may have contributed to the lack of performance effects found by Graham et al (1998). Hodgson et al (2013) used a time trial performance measure, which has previously been shown to be highly reproducible (CV ~ 3%), allowing for greater sensitivity to smaller differences in performance (Jeukendrup et al, 1996). The data analysis of Graham et al (1998) resulted in a statistical power that was smaller than Hodgson et al (2013); perhaps the reason similar changes in performance following caffeine and coffee intake (5%) were detected.
But what about the chlorogenic acid concentration?!
As coffee is only ~2% caffeine; the remainder composed of chlorogenic acids, ferulic acid, caffeic acid, nicotinic acid as well as other unidentifiable compounds (Desbrow & Leveritt, 2006). The composition and preparation of coffee in each study may also explain ergogenic discrepancies.
The source of coffee beans, roasting, storage and preparation (brewing and filtering) dramatically alters the caffeine and chlorogenic acid content of the coffee (Desbrow & Leveritt, 2006).
Graham et al (1998) speculated that chlorogenic acids found in coffee may have blunted the physiological effects of caffeine, preventing an improvement in exercise performance. However the authors did not report measurements of chlorogenic acids in coffee or in plasma to support this speculation. Despite the compounds present in coffee, the authors reported that the bioavailability of plasma caffeine and paraxanthines did not differ to caffeine (1998). In-vitro studies suggest that chlorogenic acids antagonize adenosine receptor binding of caffeine (de Paulis et al, 2002) and cause blunted heart rate and blood pressure in rats (Tse, 1992). However, in-vivo there is no evidence to suggest that chlorogenic acids, especially at low nanomolar concentrations impact the mechanisms of caffeine that lead to the ergogenic effects: regular coffee (1.1 mg/kg/BW) consumed prior to the ingestion of different doses of caffeine (37 mg/kg/BW) has been shown not to affect the ergogenic effects of caffeine (McLellan & Bell, 2004).
Data derived from Hodgson et al (2103) does not support the hypothesis that chlorogenic acids found in coffee impair the ergogenic effects of caffeine. Although the compounds found in coffee may alter the metabolic effects, it is yet to be determined if lower doses of caffeine, when ingested as coffee, offer the same ergogenic effects.
This would offer an applicable, realistic nutritional strategy for athletes pre-competition or to induce specific targeted training adaptations via manipulating stimulus.
So For Now Drink Coffee…. and lotsssss of it? – Ermmmmmm … Kind of!Â
Butts N, D C (1985) Effect of caffeine ingestion on cardiorespiratory endurance in men and women. Res Q Exerc Sport 56: 301-305.
Costill DL, Dalsky GP, Fink WJ (1978) Effects of caffeine ingestion on â€¨metabolism and exercise performance. Med Sci Sports 10: 155-158.
de Paulis T, Schmidt DE, Bruchey AK, Kirby MT, McDonald MP, et al. (2002) Dicinnamoylquinides in roasted coffee inhibit the human adenosine transporter. European journal of pharmacology 442: 215-223.
Desbrow B, Leveritt M (2006) Awareness and use of caffeine by athletes competing at the 2005 Ironman Triathlon World Championships. International journal of sport nutrition and exercise metabolism 16: 545-558.
Graham TE, Hibbert E, Sathasivam P (1998) Metabolic and exercise endurance effects of coffee and caffeine ingestion. J Appl Physiol 85: 883-889.
Hodgson AB, Randell RK, Jeukendrup AE (2013) The Metabolic and Performance Effects of Caffeine Compared to Coffee during Endurance Exercise. PLoS ONE 8(4): e59561. doi:10.1371/journal.pone.0059561
Jeukendrup A, Saris WH, Brouns F, Kester AD (1996) A new validated endurance performance test. Med Sci Sports Exerc 28: 266-270.
McLellan TM, Bell DG (2004) The impact of prior coffee consumption on the subsequent ergogenic effect of anhydrous caffeine. International journal of sport nutrition and exercise metabolism 14: 698-708.
Tse SY (1992) Cholinomimetic compound distinct from caffeine contained in â€¨coffee. II: Muscarinic actions. Journal of pharmaceutical sciences 81: 449-452.
Wiles JD, Bird SR, Hopkins J, Riley M (1992) Effect of caffeinated coffee on running speed, respiratory factors, blood lactate and perceived exertion during 1500-m treadmill running. Br J Sports Med 26: 116-120.