Effects of Bang® Keto Coffee Energy Drink on Metabolism and Exercise Performance in Resistance-Trained Adults: A Randomized, Double-blind, Placebo-controlled, Crossover Study

Abstract

Background: Energy drinks are often consumed by the general population, as well as by active individuals seeking to enhance exercise performance and augment training adaptations. However, limited information is available regarding the efficacy of these products. Thus, the purpose of this study was to determine the effects of a commercially available caffeine- and protein-containing energy drink on metabolism and muscular performance.

Methods: Sixteen resistance-trained males (n = 8; mean ± SD; age: 22.4 ± 4.9 years; body mass: 78.8 ± 14.0 kg; body fat: 15.3 ± 6.4%) and females (n = 8; age: 24.5 ± 4.8 years; body mass: 67.5 ± 11.9 kg; body fat: 26.6 ± 7.1%) participated in this randomized, double-blind, placebo-controlled, crossover study. Following a familiarization visit, participants completed two identical visits to the laboratory separated by 5-10 days, each of which consisted of indirect calorimetry energy expenditure (EE) assessments before and after consumption of the beverage (Bang® Keto Coffee; 130 kcal, 300 mg caffeine, 20 g protein) or placebo (30 kcal, 11 mg caffeine, 1 g protein) as well as after exercise testing. In addition, participants' subjective feelings of energy, fatigue, and focus as well as muscular performance (leg press one-repetition maximum and repetitions to fatigue, maximal isometric and isokinetic squat testing) were assessed. Multiple repeated measures ANOVAs with Tukey post-hoc tests were used to analyze data. Estimates of effect size were quantified via partial eta squared (ηP2) and Hedge's g.

Results: A significant interaction effect was identified for EE (p < 0.001, ηP2 = 0.52) but not respiratory exchange ratio (p = 0.17, ηP2 = 0.11). Following consumption of the beverage, EE was 0.18 [corrected] kcal·min- 1 greater than placebo at the post-beverage time point (p < 0.001) and 0.08 [corrected] kcal·min- 1 greater than placebo at the post-exercise time point (p = 0.011). However, no between-condition differences were detected for any subjective or muscular performance outcomes.

Conclusions: The results of this study suggest that consumption of the energy drink had minimal effects on lower-body muscular performance and subjective factors in the context of a laboratory setting. However, the beverage was found to significantly increase energy expenditure compared to placebo immediately following ingestion as well as during the recovery period after an exercise bout, suggesting that active individuals may improve acute metabolic outcomes via consumption of a caffeine- and protein-containing energy drink.

Trial registration: This trial was prospectively registered at ClinicalTrials.gov (Identifier: NCT04180787 ; Registered 29 November 2019).

Keywords: Caffeine; Energy drinks; Metabolism; Performance; Protein.

Conflict of interest statement

Guillermo Escalante has served as a scientific consultant for VPX (Vital Pharmaceuticals) sports nutrition. The remaining authors declare that they have no competing interests.

Figures

Fig. 1

Testing Session Overview. ASA24: Self-administered dietary recall; BM: Body mass assessment; EE Assessment: Energy expenditure assessment; VAS: Visual analog scale

Fig. 2

Metabolism. Changes in resting metabolic rate (RMR; panel a) and respiratory exchange ratio (RER; panel b), assessed via indirect calorimetry, are displayed. For RMR, a significant condition by time interaction was observed using ANOVA with repeated measures. Subsequently, Tukey post-hoc comparisons were performed. Asterisks indicate significant differences between conditions at the specified time point, while E and PL indicate significant differences in the energy drink or placebo conditions, respectively, relative to the pre-beverage value. For RER, a significant main effect for time was observed. T indicates a significant difference from the pre-beverage time point in both groups combined. Error bars indicate the 95% confidence intervals for within-subjects SE due to the repeated-measures design of this study [24, 28]

Fig. 3

Squat Performance. Values for isokinetic and isometric performance on the mechanized squat device are displayed, with both time points occurring after beverage ingestion. Pre-RE tests were performed following the second indirect calorimetry assessment and prior to the resistance exercise (RE) testing, while post-RE tests occurred immediately after RE (leg press) testing. Values are displayed for peak concentric force (PFCON; panel a), peak eccentric force (PFECC; panel b), peak isometric force at the 120-degree knee angle (PFISO120; panel c), peak isometric force at the 150-degree knee angle (PFISO150; panel d), peak rate of force development at the 120-degree knee angle (RFD120; panel e), and peak rate of force development at the 150-degree knee angle (RFD150; panel f). Data were analyzed using ANOVA with repeated measures, along with Tukey post-hoc comparisons. A main effect of time was present for PFISO120 (p < 0.001, ηP2 = 0.65), along with a trend for a main effect of condition (p = 0.07, ηP2 = 0.19). Additionally, a main effect of time was present for RFD150 (p = 0.028, ηP2 = 0.28). Error bars indicate the 95% confidence intervals for within-subjects SE due to the repeated-measures design of this study [24, 28]

Fig. 4

Leg Press Performance. Paired-samples t-tests were performed to examine group-level differences in leg press 1-repetition maximum (1RM; panel a) and repetitions to failure (panel c). No differences between conditions were observed. Error bars indicate SD, and individual responses are displayed in (panels b and d)

Fig. 5

Subjective Variables. Subject evaluations of energy (a), fatigue (b) and focus (c), evaluated via digital analog scale, are displayed. Data were analyzed via ANOVA with repeated measures, and main effects of time were observed for all three variables. Results of Tukey post-hoc comparisons are displayed, with shared letters indicating no difference between time points. Error bars indicate the 95% confidence intervals for within-subjects SE due to the repeated-measures design of this study [24, 28]