A study published in the Journal of the International Society of Sports Nutrition found that ingesting caffeinated chewing gum had no performance enhancing effects on the Special Judo Fitness Test (SJFT) among elite judo athletes.
Previous studies have reported positive effects of caffeine on sport performance. Caffeinated chewing gum, which allows caffeine to be absorbed directly into the bloodstream, has been found to improve performance in sports such as endurance running and cycling. However, its efficacy had not yet been tested in combat sports.
Aleksandra Filip-Stachnik and colleagues recruited nine male healthy elite judoists, who were all black-belt members of the Polish national team. While athletes had previous experience performing the SJFT (achieving at least “good” level), none had previously used caffeinated chewing gum.
Participants “underwent a randomized, double-blind, placebo controlled, crossover experiment where each participant acted as his own control.” They participated in three identical trials that involved ingesting two chewing gums, and various performance measures specific to judo. There were seven days between trials to allow for complete caffeine wash-out and recovery. The trials differed in terms of the type of gum that was ingested: 1) two non-caffeinated placebo chewing gums, 2) a caffeinated chewing gum (200 mg of caffeine) and a placebo chewing gum, and 3) two caffeinated chewing gums (400 mg of caffeine in total).
Participants’ blood sample was obtained to assess their blood lactate concentration at baseline. They began trials by wearing their judogis and ingesting the first chewing gum; they chewed the gum for 5 minutes and were required to dispose of it in a container afterwards. Participants proceeded to perform a 15 minute warm-up. Next, they performed the first SJFT, which involves “ippon seoi nage” (or one-armed shoulder) throws on two partners.
Afterward, the researchers obtained blood lactate concentration, a self-report rating of perceived exertion, and monitored heart rate. Following 5 minutes of passive recovery, participants performed a 4 minute simulated combat activity, with blood lactate concentration measurement taken afterwards. Next, participants ingested the second chewing gum, chewing for 5 minutes, and rested for 15 minutes prior to performing the second SJFT. Once again, a rating of perceived exertion, blood lactate concentration, and heart rate were obtained. All experiments took place at the same time of day, during typical training hours.
Compared to placebo gum, ingesting caffeinated chewing gum – of up to 400mg of caffeine – did not increase the number of throws performed during the SJFT, or induce changes in the SJFT index. Further, caffeine did not affect participants’ self-perceived exertion, blood lactate concentration or heart rate.
The researchers note a few potential limitations. First, they administered absolute doses of caffeine rather than doses personalized to participants’ body mass. However, further analyses accounting for this limitation revealed a similar pattern of results. Second, blood caffeine concentration metrics were not obtained, thus, the researchers were unable to verify the amount of caffeine concentration obtained through the chewing gum. Lastly, only two repetitions of the SJFT were implemented. The researchers suggest future investigations explore the efficacy of different caffeine doses, and implement other performance tests – such as the number of offensive movements enacted during combat.
The study, “Effects of acute ingestion of caffeinated chewing gum on performance in elite judo athletes”, was authored by Aleksandra Filip-Stachnik, Robert Krawczyk, Michal Krzysztofik, Agata Rzeszutko-Belzowska, Marcin Dornowski, Adam Zajac, Juan Del Coso and Michal Wilk.