Role of Energy Drinks and Pre-Workout Supplements on Performance and Training

Disclosures: Receive industry sponsored research grants and serve as a scientific and legal consultant.

Richard B. Kreider, PhD, FACSM, FASEP, FISSN, FACN, FNAKProfessor & Executive Director, Human Clinical Research Facility

Director, Exercise & Sport Nutrition LabDepartment of Health & Kinesiology

Texas A&M University

rbkreider@tamu.edu

ExerciseAndSportNutritionLab.comEssentialsofSportNutrition.com

Energy Drinks and Pre-Workout Supplements

Energy drinks (ED) and energy shots (ES) have become a popular pre- and post-exercise drinks among athletes.

They typically contain carbohydrate (i.e., 10 – 15 grams/100 ml or 10-15% solution), electrolytes, and caffeine along with nutrients purported to improve mental focus, attention, and/or alertness.

Additionally, a number of caffeine containing pre-workout supplements (PWS) have been developed which are commonly consumed as a drink prior to and/or during exercise.

Energy Drinks and Pre-Workout Supplements

While occasional ingestion of these types of products appears to be safe and may offer some ergogenic benefit, individuals who consume these products indiscriminately need to be careful to consider how ingestion of these products may affect total daily intake of caffeine and other stimulants throughout the day in order to-minimize any adverse events and/or harmful side effects.

Concerns have been raised about excessive use of EDs in children and adolescents; use of EDs with alcohol; and, excessive consumption of EDs in populations with medical conditions (e.g., diabetics, CV disease, hypertension, etc.).

Overview

Composition of EDs and ESs

Ergogenic Value of Common Ingredients

Ergogenic Value of EDs, ESs, and PWSs on Performance and Cognitive Function

Safety Considerations

Conclusions

Campbell et al. JISSN. 10:1, 2013

Campbell et al. JISSN. 10:1, 2013Kreider RB. J Nutri Dietary Supp, 10:35-44, 2018

Example of Energy Drink IngredientsIngredient A B C D ECalories 100 110 140 120 140Carbohydrate 27 28 31 32 30Calories from Fat - - - -Vitamin C - 100 mg - 100 mg 6.7mgThiamin - 0.1 mg - - 0.2 mgRiboflavin B2 1.7 mg 1.5 mg 3.4 mg 20% 0.2 mgNiacin B3 20 mg 21.7 mg 20 mg 10% 2.2 mgVitamin B6 40 mg 2.1 mg 2 mg 10% 1.5 mgVitamin B12 6 mcg 4.5 mcg 6 mcg 10% 4.7 mcgPantothenic Acid - 36 mg - 10% 1.1 mgSodium 180 mg 200 mg 40 mg 75 mg 190 mgPotassium - 10 mg 10 mg - 65 mgPhosphorus - - - 40 mg 90 mgTaurine 1,000 mg 600 mg 1000 mg -Panax Ginseng 200 mg - 25 -Proprietary Blend 2,500 mg

L-Carnitine, Glucose, Caffeine, Guarana,

Inositol, Glucuronolactone,

Maltodextrin

Caffeine (77 mg) 325 mgGinko Biloba (150 mg),

Caffeine (80 mg), Guarana (25 mg), Inositol (25 mg), L-Carnitine (25

mg), Milk Thistle (20 mg)

Guarana, maltodextrin, caffeine, taurine, panax

ginseng, calcium

Citrulline Malate, L-Glutamine, L-Arginine,

Quercetin, L-Leucine, L-Valine,

Campbell et al. JISSN. 10:1, 2013

Example of Energy Shot IngredientsIngredient A B C D ECalories 4 4 20 9 0

Carbohydrate - - 4 g 1 g 0Calories from Fat

- -- -

Vitamin C - 100 mg - - 126%Niacin 30 mg 33 mg 33 mg -Vitamin B6 40 mg 40 mg 40 mg -Folic Acid 400 mcg 400 mcg 400 mcg -Vitamin B12 500 mcg 500 mcg 500 mcg -Sodium 18 mg 0 mg 0 mg - 10Potassium - 10 mg 10 mg - 26Proprietary Blend

1,870 mgTaurine,

Glucuronolactone, Malic Acid, N-Acetyl

L-Tyrosine, L-Phenylalanine,

Caffeine, Citocoline

2,300 mgGlucouronolactone

(425 mg), N-Acetyl L-Tyrosine (400 mg), L-Phenylalanine (375 mg), Taurine (350

mg), Malic Acid 300 mg), Caffeine (200

mg), Green Tea Extract (150 mg),

Ginseng Extract (150 mg)

2,200 mgGlucouronolactone (420

mg), L-Phenylalanine (380 mg), D-Ribose (350 mg), N-Acetyl L-Tyrosine (325 mg), Malic Acid (300 mg), Caffeine (175 mg), Green Tea Extract (150

mg), Ginseng Extract (100 mg)

910 mgCaffeine Citrate, Caffeine

Anhydrous, Evoburn, Octapomine,

Gugulsterone E & Z, Yerbe Mate, Green Tea,

Synephrine, cAMP, Vinocetine, Yohimbe HCL

527 mgBeta-Alanine, Vitamin C, Caffeine Anhydrous (158 mg), Evoburn, N-

Acetyl-L-Tyrosine, Hordinine, 5-Hydroxy-L-

Trypotophan (5-HTP), Potassium, N-methyl

Tyramine, Sulbutlamine,

Vinpocetine, YohimbineHCI, St. John's Wort

Extract

Campbell et al. JISSN. 10:1, 2013

Example of Pre-Workout Supplement IngredientsIngredient A B C D E

Calories 48 48 10.4 10.4 12.0

Carbohydrate 12 12 2.6 2.6 3.0

Beta Alanine (g) 3 3 3.2 2.1

Creatine Nitrate (g) 2 2 2 3.0

Arginine α-KG (g) 2 2 2

Arginine Nitrate (g) 1.3

Vitamin C (mg) 500 500 500

N-Acetyl-L-Tyrosine (mg) 300 300 300

Caffeine (mg) 284 284 300 200

15% L-DOPA extract (mg) 15 15 150

Vitamin B12 (mcg) 70 70 1.8 45

Niacin (mg) 60 60 0.5 65

Folate (mg) 50 50 0.5 325

p-Synephrine (mg) 20

Tetramethyluric acid (mg) 10

Theacrine (mg) 10

Pyridoxal 5-phosphate (mg) 1.48

Potential Ergogens

Caffeine

Carbohydrate

Nutrients that promote mental focus / cognition

Stimulants

Other Nutrients Campbell et al. JISSN. 10:1, 2013

Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate dosages (3-6 mg/kg)

Caffeine can enhance vigilance during bouts of extended exhaustive exercise, as well as periods of sustained sleep deprivation.

Caffeine is ergogenic for sustained maximal endurance exercise, and has been shown to be highly effective for time-trial performance.

Caffeine supplementation is beneficial for high-intensity exercise, including team sports such as soccer and rugby, both of which are categorized by intermittent activity within a period of prolonged duration.

Goldstein et al. JISSN. 7:5, 2010

CaffeineISSN Position Stand

The metabolic and performance effects of caffeine compared to coffee during endurance exercise Hodgson et al. PLoS One. 8(4): e59561, 2016

• 8 trained male cyclists/triathletes completed 30-min of steady-state (SS) cycling at approximately 55% VO2maxfollowed by a 45-min energy based target time trial (TT).

• 1 hr prior to exercise, participants consumed drinks consisting of CAF (5 mg CAF/kg BW), instant coffee (5 mg CAF/kg BW), instant decaffeinated coffee or PLA.

• Performance times during the TT were significantly faster (∼5.0%) for both caffeine and coffee when compared to PLA and decaf (38.35±1.53, 38.27±1.80, 40.23±1.98, 40.31±1.22-min respectively, p<0.05).

• Average power for CAF and coffee during the TT was significantly greater when compared to PLA and decaf (294±21 W, 291±22 W, 277±14 W, 276±23 W respectively, p<0.05).

• Both caffeine (5 mg/kg/BW) and coffee (5 mg/kg/BW) consumed 1 h prior to exercise can improve endurance exercise performance.

Energy Drinks, Shots, and PWSsCaffeine Considerations

Most provide a similar amount of caffeine as a premium cup of coffee (e.g., 75 – 200 mg serving)

Use of EDs or ESs prior to and/or during exercise can serve as an effective means of providing caffeine.

Must consider all sources of caffeine and stimulants in drinks/shots.

Must make sure excessive caffeine intake doesn’t decrease motor skills.

Caffeine is no longer a banned substance by the IOC or WADA.

There is genetic sensitivity to caffeine.

Carbohydrate

• Athletes undergoing prolonged bouts (2–3 h) of exercise training can oxidize CHO at a rate of 1–1.1 g per-min or about 60 g/hr.

• Several reviews advocate the ingestion of 0.7 g of carbohydrate/kg/hr during exercise in a 6–8% solution (i.e., 6–8 g per 100 ml of fluid).

• Glucose, sucrose, maltodextrins and amylopectin are oxidized at high rates, while fructose, galactose and amylose are oxidized at lower rates (~25-50% lower).

• Sports drinks typically contain a mixture of various types of carbohydrates designed to optimize exogenous carbohydrate oxidation.

• EDs typically contain a carbohydrate source (e.g., glucose, sucrose, maltodextrin, etc.) and/or glucuronolactone (an ingredient metabolized into xylulose) and can serve as an effective source of CHO prior to and/or during exercise.

Kerksick et al., JISSN. 15:38, 2018

Energy DrinksCarbohydrate Considerations

• Source of CHO? Most are high GI and therefore may

promote hypoglycemia in some athletes

• Concentration of CHO? Must ingest enough water during

exercise to offset higher percentage of CHO in drinks

• Timing of Ingestion? Hypoglycemia? Promote glycogen replenishment

after exercise?

Other Potential Ergogenic NutrientsCognition / Mental Focus

Ingredient Potential Ergogenic Value Scientific SupportTaurine Improved mental focus, concentration, serve as

antioxidant, glucose homeostasisSome supportive evidence with EDs and fed animals

Gingko Biloba Improve memory and mental concentration Some supportive evidence on memory (e.g., 120 mg/d). Role in EDs unknown.

L-Tyrosine Prevents depletion of catecholamines, may ameliorate declines in cognition with acute stress

Some supportive evidence on cognition (e.g., 2 g/d, 150 mg acute ingestion with cold exposure). No evidence on improving exercise.

Citocoline Intermediate in the generation of phosphatidylcholine from choline. Increasedopamine receptor densities and delay memory impairment.

Some supportive evidence with large doses (8.5 g prior to and during exercise) and in fed animals. 0.5 g/d for 6-wks increased brain PCr. Role in EDs unknown.

5-Hydroxy-L-Trypotophan (5-HTP)

Precursor to serotonin. Purported antidepressant, appetite suppressant, & sleepaid.

Some evidence in treatment of depression and 5-HT fed animals on muscle performance. Role on exercise performance and in EDs unknown.

St. John’s Wort Anti-depressant. Some supportive evidence. No known effects at dosages found in EDs.

Campbell et al. JISSN. 10:1, 2013

Ingredient Potential Ergogenic Value Scientific SupportCaffeine Stimulant. Increases metabolism and fat oxidation. Increases alertness, mood, cognitive

function. Increases fat oxidation and spares glycogen utilization.

Guarana Natural source of caffeine. Similar properties to caffeine. Similar to caffeine effects.

Green Tea Extract Contains high amounts of caffeine and catechin polyphenols (e.g., epigallocatechin gallate or EGCG). Serves as antioxidant.

Similar to caffeine effects. Specific role in EDs unknown

Synephrine Alternative to ephedrine. Naturally derived from Citrus aurantium. Stimulant with less CV effects. Purported to increase metabolism and promote weight loss.

Evidence of a mild stimulant effect onmetabolism.

Yerba mate Contains three xanthines (caffeine, theobromine, and theophylline). Similar properties to caffeine

Similar to caffeine effects. Effects in EDs unknown.

Yohimbine Alkaloid with stimulant and aphrodisiac properties. Similar to caffeine effects. Effects in EDs unknown.

Tyramine Naturally-occurring monoamine derived from tyrosine. Acts as a catecholamine (dopamine, NE, Epi) releasing agent. Degraded to octopine. Increases blood pressure and can serve as neurotransmitter.

CV stimulant. Effects in EDs unknown.

Vinpocetine Alkaloid of vincamine extracted from periwinkle plant (Vinca)-minor. Vasodilatory and memory enhancing properties.

No known effects at dosages found in EDs. Campbell et al. JISSN. 10:1, 2013

Other Potential Ergogenic NutrientsCognition / Mental Focus

Ingredient Potential Ergogenic Value Scientific Support

Panax Ginseng Contains ginsenosides which are purported to have anti-inflammatory, antioxidant, and anticancer effects. Enhance perceptions of energy, increase stamina and improve nitrogen balance.

Most well-controlled research do not support the ergogenic effects for ginseng. No known effects at dosages found in EDs.

L-Carnitine Involved in shuttling long chain fatty acids into mitochondria. Purported to promote lipolysis.

Limited supportive evidence. No known effects at dosages found in EDs.

D-Ribose Involved in ATP synthesis. Theoretically, D-ribose supplementation can increase ATP availability.

Limited evidence even at high doses. No known effects at dosages found in EDs.

Beta Alanine Increases muscle carnosine levels. Increases muscle buffering.

Growing scientific evidence of improved anaerobic capacity (2-4 g/d). No known effects at dosages found in EDs.

Inositol Carbohydrate that is not classified as sugar. Involved in insulin signaling, nerve transmission, serotonin modulation, fat oxidation.

No known effects at dosages found in EDs.

Citrulline Malate Optimizes blood flow via arginine-nitric oxide pathway. Purported to reduce fatigue and buffer acidity during exercise.

Evidence that 6 g/d for 15-d decreased fatigue and 8 g before RE decreased fatigue. No known effects in EDs.

Quercetin Reported to have antioxidant, anti-inflammatory, antiviral, and immunomodulatory effects.

Several studies indicate that 1 g/d for 7 d increase maximal aerobic capacity and time to fatigue. Campbell et al. JISSN. 10:1, 2013

Other Potential Ergogenic NutrientsCognition / Mental Focus

• Pre-Exercise Increase CHO availability Increase mental focus and/or alertness Stimulate fat oxidation to help spare

muscle glycogen

• During Exercise Source of CHO and caffeine

• After Exercise Increase insulin Promote glycogen replenishment

Energy DrinksPotential Uses

Performance

Energy Drinks

Improved cycling time-trial performance after ingestion of a caffeine energy drink. Ivy et al. Int J Sport Nutr Exerc Metab. 19(1):61-78, 2009

6 male and 6 female cyclists consumed 500 ml of either flavored PLA or RB containing 2.3 mg/kg of caffeine 40-min before performing a simulated cycling time trial (70% Wmax).

Performance was 4.7% faster with ED (3,690±64 vs. 3,874±93 s) with no difference observed in RPE.

β-endorphin levels increased during exercise, with the increase for ED approaching significance over PLA (p=0.10).

No difference in substrate utilization

The effectiveness of two energy drinks on selected indices of maximal cardiorespiratory fitness and blood lactate levels in male athletes Rahnama et al. J Res Med Sci. 15(3):127-32, 2010

10 male students ingest RB or Hype® (containing 24.8 g of carbohydrate, 75 mg caffeine, 1 g of taurine, and 600 mg glucuronolactone) 40-min prior to performing a maximal exercise capacity test compared to a PLA containing water and citrus substances.

Results revealed that RB and Hype ED consumption increased maximal aerobic capacity (+11.5%, +9.9%) and time to exhaustion (+10.5%, +9.7%) compared to PLA with no differences observed in heart rate or lactate responses.

Effect of Red Bull energy drink on repeated Wingate cycle performance and bench-press muscle enduranceForbes et al. Int J Sport Nutr Exerc Metab. 18(5):542, 2008

15 healthy adults (11 male and 4 female) were randomized to consume RB (2 mg/kg caffeine) or PLA 60-min prior to exercise in crossover manner.

Subjects performed bench press endurance (3 sets at 70% 1RM) and 3 x 30-s Wingate’s tests.

RB increased total BP repetitions over three set (34±9 vs. 32±8) by 6% with no effects on Wingate peak power (701±124 vs. 700±132 W) or average power (479±74 vs. 471±74 W).

Effects of a caffeine-containing energy drink on simulated soccer performanceDel Coso et al. PLoS One 7(2), e31380, 2012

19 semi-pro soccer players sugar-free RB providing 3 mg/kg caffeine or a PLA 1 hr before exercise in a randomized and cross-over manner.

After 60-min, subjects performed a 15-s maximal jump test, a repeated sprint test (7×30 m; 30 s of active recovery) and played a simulated soccer game.

ED ingestion increased mean jump height (34.7±4.7 v 35.8±5.5 cm; P<0.05), mean sprint running speed (25.6±2.1 v 26.3±1.8 km · h−1; P<0.05); total distance covered at a speed > 13 km/h during the game (1205±289 v 1436±326 m; P<0.05); and, the number of sprints during the whole game (30±10 v 24±8; P<0.05).

Dose response effects of a caffeine-containing energy drink on muscle performance: a repeated measures design Del Coso et al. JISSN. 9.1.21, 2012

12 active subjects ingested an ED containing 1 or 3 mg/kg caffeine or a PLA 1-hr before exercise in a randomized and cross-over manner.

After 60-min, subjects had REE, HR & BP, and performed half-squat and bench press tests with loads from 10 to 100% 1RM.

ED slightly increased MAP (82 to 90 mmHg and HR (57 to 62 bpm) in a dose response manner with no effect on REE.

Ingestion of 3 mg/kg increased maximal power in the half-squat by 6.7% (2554 to 2726 W) and bench-press power by 7.4% (349 to 375 W) with no effects of ingesting the ED with 1 mg/kg.

Effect of a pre-workout energy supplement on acute multi-joint resistance exercise Gonzalez et al. J Sports Sci Med. 10(2):261-6, 2011

Subjects ingested a PLA (P) or a ED (caffeine, taurine, glucuronolactone, creatine, β-alanine, and the amino acids; leucine, isoleucine, valine, glutamine and arginine) 10-mins prior to resistance exercise.

Subjects performed 4 sets of no more than 10 repetitions of either squat or bench press at 80% of 1RM with 90-sec of rest between sets.

Ingestion of RB 10-mins prior to exercise increased the number of repetitions performed during 4 sets of the squat or bench press exercise by 11.9%.

Average power output for the workout was significantly higher for subjects consuming RB.

Average Peak Power

Average Power

Effect of sugar-free Red Bull energy drink on high-intensity run time-to-exhaustion in young adults Candow et al. JSCR: 23(4):1271-75, 2009

17 active college students performed a run to exhaustion (RTE) at 80% of VO2max.

Subjects consumed sugar free RB (2 mg/kg caffeine and 25 mg/kg taurine) or a PLA 1-hr before exercise in a randomized and cross-over manner.

No significant differences between groups in RTE, RPE, or blood lactate.

Sugar-free RB provided no ergogenic benefit on RTE.

Effects of red bull energy drink on repeated sprint performance in women athletesAstorino et al. Amino Acids: 42(5), 1803-8, 2012

15 female college soccer players performed 3 x 8 sets of sprint t-test

Subjects consumed RB (1.3 mg/kg caffeine and 1 g taurine) or a PLA 1-hr before exercise in a randomized and cross-over manner.

No significant differences between groups on sprint time, HR, or RPE responses.

One serving of RB prior to sprint-exercise provided no ergogenic benefit in female athletes.

Performance

Energy Shots

The effects of caffeinated “energy shots” on time trial performance Schubert et al. Nutrients. 5(6):2062-75, 2013

Evaluated the effects of consuming an energy shot on 5-km time trial performance in trained runners.

Participants ingested in a randomized, counterbalanced, and crossover manner prior to performing a 5-km time trial on a treadmill: PLA (2 oz. of Dragonfruit Vitamin Water™ with no

caffeine) Guayaki Yerba Mate™ Organic Energy Shot

containing 80 mg of caffeine RB Energy Shot™ containing 80 mg caffeine

The researchers found that time trial performance was not affected by ES ingestion.

The influence of commercial energy shots on response time and power output in recreational cyclistsSeifert and Connor. JISSN. 11:56, 2014

Evaluated the effects of consuming Body Glove Surge® (18 grams CHO, 3 grams PRO, and 150 mg caffeine per serving), 5 Hour Energy® (~205 mg caffeine, ~480 mg taurine, 30 mg niacin), or non-caloric PLA on time trial performance following cycling for 120-mins at 70% of peak oxygen uptake with intermittent 2-min intervals at 90% of peak oxygen uptake.

Participants ingested a half dose of the ESs at 30, 60, and 90-mins of exercise with 75 ml of water.

Participants then performed a 6-min time trial. Results revealed that ingestion of the ES significantly

improved cycling power output and auditory response time following 2 hours of moderate and high intensity interval cycling compared to RB and PLA ingestion.

Effects of energy beverage consumption on pistol aiming steadiness in law enforcement officers Monaghan et al. JSCR. 31(9):2257-61, 2017

10 police officers had their pistol aiming steadiness determined before and 30 minutes after consumption of an ES or PLA.

ES significantly impaired pistol steadiness, whereas the placebo yielded no significant difference in aiming steadiness.

Results revealed that ingesting an energy drink may have an ergolytic effect on fine motor skill.

Performance

Pre-Workout Supplements

Improved time to exhaustion following ingestion of the energy drink Amino Impact. Walsh et al. JISSN: 7:14, 2010

15 subjects (9 male, 6 female) ingested a PLA or a 500 ml of an ED containing 2.05 g of caffeine, taurine, and glucuronolactone; 7.9 g of BCAA, L-arginine, and L-glutamine; 5 g of di-creatine citrate; and, 2.5 g of β-alanine.

Subjects performed treadmill runs to exhaustion @ 70% of VO2 max.

Subjects consuming ED were able to run 12.5% longer than P.

Subjects in ED group reported greater focus, energy, and less fatigue before exercise.

Subjects in the ED group reported greater focus and energy at 10-min of exercise.

No differences were seen after exercise in focus, energy, or fatigue.

Effect of a pre-exercise energy supplement on the acute hormonal response to resistance exerciseHoffman et al. JSCR. 22(3):874-82, 2008

8 resistance-trained males ingested a PLA or ED (5.4 g BCAA, 3.2 g EAA, 5 g creatine, 1.5 g taurine, 350 mg glucuronolactone, 110 mg caffeine) or a PLA 10-min prior to performing 6 sets of squats @ 75% 1RM

Total number of repetitions and training volume tended (p=0.08) to be higher with S compared to P.

Serum growth hormone and insulin concentrations were significantly higher in the S group.

The acute effects of multi-ingredient pre-workout ingestion on strength performance, lower body power, and anaerobic capacityJagim et al. JISSN. 13.1, 2016

12 males ingested a PWS (4 g carbohydrate, 130 mg sodium, 2 g creatine hydrochloride, 2 g beta-alanine, 1.5 g betaine, 1 g taurine, 600 mg N-aceytl L-cysteine, 300 mg alpha-glyceryl phosphoryl choline, 6 g citrulline malate, 500 mg beta vulgaris [beet root extract], 3 g L-leucine, 1.5 g L-isoleucine, 1.5 g valine, 1.5 g L-tyrosine, 300 mg caffeine anhydrous, 50 mcg huperzine A, and 5 mg Piper Nigrum Fruit extract) or PLA 30-mins prior to exercise.

Participants performed a counter movement vertical jump test, 5 sets of 5 repetitions at 85 % of 5RM on the back squat and bench press, followed by a single set to failure, and an anaerobic capacity sprint test.

Results revealed that the number of repetitions performed in the final set to failure in the BP as well as anaerobic sprint capacity was significantly greater following PWS ingestion.

The effect of acute pre-workout supplementation on power and strength performanceMartinez et al. JISSN. 13.29, 2016

13 males reported to the laboratory on four separate occasions, each separated by one week.

Performance testing included a medicine ball put (MBP) to determine upper body explosive power, vertical jump test (VJ) to determine lower body explosive power, one-rep maximum bench press (1-RM) for determining upper body strength, and a Wingate Anaerobic Power Test (WAnT) to determine measures of anaerobic power.

On week three, subjects were randomly assigned to ingest either a pre-workout supplement (SUP) containing carbohydrate, β-alanine, creatine nitrate, L-Tyrosine, ribose, amino acids, and caffeine and other nutrients or a PLA and again complete the performance testing protocol.

Performance testing commenced 20-min following ingestion of both treatments, which was similar to previous investigations.

Ingestion of a PWS significantly improved anaerobic peak and mean power in comparison to ingesting PLA.

• In a DBCPC manner; 25 apparently men and women had resting BP, HR, 12-lead ECG, and REE measured for 10-min.

• Participants ingested a flavored PLA (P); a PWS containing 3.0 g beta alanine, 2 g creatine nitrate, 2 g arginine AKG, 300 mg of N-acetyl tyrosine, 270 mg caffeine, 15 mg of Mucuna pruriens; or, the PWS with 20 mg of synephrine (PWS+S).

• Participants had HR, BP, REE, ECG’s, perceptions about readiness to perform, cognitive function (Stroop Color-Word test), BP & LP performance (2 sets of 10 repetitions at 70% of 1RM and 1 set to failure), and Wingate anaerobic capacity (WAC) sprint performance determined prior to and following exercise.

• No clinically significant differences were observed among treatments in HR, BP, ECG, or general clinical blood panels.

• PWS and PWS + S ingestion promoted greater changes in REE responses.

• Participants reported higher perception of optimism about performance and vigor and energy and there was evidence that PWS and PWS + S improved changes in cognitive function scores from baseline to a greater degree than PLA after 1 or 2 h.

• No statistically significant differences were observed among treatments in total bench press lifting volume, leg press lifting volume or WAC sprint performance.

Effects of acute ingestion of a pre-workout dietary supplement with and without p-synephrine on resting energy expenditure, cognitive function and exercise performanceJung et al. JISSN. 14:3: 2017

Chronic Use

• 25 resistance-trained participants ingested a PLA beverage and ready to drink (RTD) beverage containing caffeine (200 mg), β-alanine (2.1 g), arginine nitrate (1.3 g), niacin (65 mg), folic acid (325 mcg), and Vitamin B12 (45 mcg) for 7-days, separated by a 7–10-day.

• On day 1 and 6, participants donated a fasting blood sample, completed an SEQ, hemodynamic challenge test, 1-RM and muscular endurance tests (3 × 10 reps @ 70% of 1-RM with the last set to failure) on the BP and LP followed by ingesting the assigned beverage.

• After 15-min, participants repeated the hemodynamic test, 1-RM tests, and performed a repetition to fatigue (RtF) test at 70% of 1-RM, followed by completing the SEQ.

• On day 2 and 7, participants donated a fasting blood sample, completed the SEQ, ingested the assigned beverage, rested 30-min, and performed a 4 km cycling time-trial (TT).

Short-Term Effects of a Ready-to-Drink Pre-Workout Beverage on Exercise Performance and Recovery Collins et al. Nutrients. 9(8), 823, 2017

• Acute RTD ingestion better maintained LP 1-RM; increased LP RtF; increased BP lifting volume; and, increased total lifting volume.

• Short-term RTD ingestion maintained baseline LP 1-RM; LP RtF; and, LP lifting volume to a greater degree than PLA.

• No significant differences were observed between treatments in cycling TT performance, hemodynamic assessment, fasting blood panels, or self-reported side effects.

Short-Term Effects of a Ready-to-Drink Pre-Workout Beverage on Exercise Performance and Recovery Collins et al. Nutrients. 9(8), 823, 2017

The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance. Smith et al. JISSN. 15.7, 2010

24 recreational athletes ingested a PWS drink containing 18 grams of whey protein, cordyceps sinensis, creatine, citrulline, ginseng, and caffeine 30-mins prior to exercise during 3-weeks of high intensity interval training (HIIT).

Results revealed the PWS significantly increased peak oxygen uptake, critical velocity, fat free mass, and training volume in comparison to an isocaloric flavored PLA containing maltodextrin.

Results demonstrated improvements in VO2max, CV, and LBM when GT is combined with HIIT.

• RT males (N=80) were randomly assigned to supplement their diet in a DBPC manner with a PLA; a PWS containing beta alanine (3 g), creatine nitrate (2 g), arginine alpha-ketoglutarate (2 g), N-Acetyl-L-Tyrosine (300 mg), caffeine (284 mg), Mucuna pruiriens extract standardized for 15% L-Dopa (15 mg); or, the PWS with Citrus aurantium (PWS+S) extract standardized for 30% synephrine (20 mg) once per day for 8-weeks during training.

• PWS and PWS + S did not increase the incidence of reported side effects or affect the number of blood values above clinical norms compared to PLA.

• No significant differences were observed among groups for body composition, resting heart and blood pressure, readiness to perform questions, 1RM strength, anaerobic sprint capacity, or blood chemistry panels.

• There was some evidence that cognitive function and 1RM strength were increased to a greater degree in the PWS and/or PWS + S groups after 4- and/or 8-weeks compared to PLA responses.

• Results provide some evidence that 4-weeks of PWS and/or PWS + S supplementation can improve some indices of cognitive function and exercise performance during resistance-training without significant side effects in apparently health males. However, these effects were similar to PLA responses after 8-weeks of supplementation and inclusion of synephrine did not promote additive benefits.

Effects of ingesting a pre-workout dietary supplement with and without synephrine for 8- weeks on training adaptations in resistance-trained males Jung et al. JISSN. 14:1, 2017

Low-calorie energy drink improves physiological response to exercise in previously sedentary men: a PLA-controlled efficacy and safety studyLockwood et al. JSCR. 24(8):2227-38, 2010

38 males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), PLA + exercise (EX-B), or PLA (NEX-B).

All participants consumed 1 drink per day for 10 weeks. EX-A and EX-B participated in 10 weeks of resistance and

endurance exercise. No significant (p > 0.05) changes were observed for body

composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in VO2peak were observed in EX-A versus EX-B.

Ventilatory threshold (VT),-min ventilation, VO2 at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups.

Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink.

Mood was not affected by energy drink use. However, when combined with exercise, PWS consumption

may significantly improve some physiological adaptations to combined aerobic and resistance training.

Safety Considerations

The vast majority of studies that have evaluated the acute ingestion of ED, ES, or PWS on exercise and/or cognitive performance have shown they are well-tolerated in healthy individuals.

Pre-exercise consumption of EDs or PWSs for up to 10-weeks during training have been reported to be well-tolerated and were not associated with any serious adverse effects.

Safety Considerations

A few studies have reported a short-term increase in resting SBP and/or DBP (e.g., 2-5 mmHg) while most studies have found no effects on resting or exercise blood pressure.

Collins et al. (2017) reported that PWS ingestion had no effects on hemodynamic responses to a postural challenge test.

Molnar et al. (2015) reported improved endothelial function after ingestion of some EDs which could provide health benefit.

Nevertheless, its prudent for individuals with hypertension to exercise caution when consuming ED, ES, and/or PWS.

Safety Considerations

Concerns have been raised about use of EDs to counteract the depressive effects of alcohol and therefore lead to excessive alcohol intake and/or intoxication.

A number of studies suggest that individuals who mix alcohol with EDs are more likely to consume more alcohol and/or engage in risky.

Use of EDs and ESs with alcohol should be discouraged (see Howland et al., JAMA, 2013).

Safety Considerations

Concerns have also been raised that indiscriminate use of EDs and/or ESs may lead to excessive caffeine intake and negative health outcomes.

Yet, the amount of caffeine found in most standard size EDs and ESs (i.e., about 80 to 200 mg) is less than that found in a premium cup of coffee depending on the size (e.g., 180 – 475 mg).

Nevertheless, since caffeine is found in many drinks and foods, care should be taken to make sure that excessive caffeine is ingested as insomnia, nervousness, restlessness, gastric irritation, nausea, vomiting, tachycardia, tremors, and anxiety with doses as low as 250 to 300 mg.

Safety Considerations

Kreider RB. J Nutri Dietary Supp, 2018

The preponderance of scientific evidence to date suggests that consumption of these products prior to exercise can improve anaerobic and endurance exercise capacity and/or cognitive performance without untoward side effects.

The amount of caffeine and other stimulants contained in EDs, ESs, and PWSs need to be considered as part of the total daily intake from food and beverages so that individuals do not unknowingly consume excessive amounts of sugar and/or caffeine.

Summary

It is prudent for individuals with uncontrolled hypertension, arrhythmias, diabetes mellitus, peripheral artery disease, and/or cardiovascular disease to avoid use of ED, ESs, and/or PWSs with known cardio-stimulant effects.

Additional research should evaluate the acute and chronic safety and efficacy of ingesting EDs, ESs and PWSs on health and performance.

Summary

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Role of Energy Drinks and Pre-Workout Supplements on Performance and Training

Disclosures: Receive industry sponsored research grants and serve as a scientific and legal consultant.

Richard B. Kreider, PhD, FACSM, FASEP, FISSN, FACN, FNAKProfessor & Executive Director, Human Clinical Research Facility

Director, Exercise & Sport Nutrition LabDepartment of Health & Kinesiology

Texas A&M University

rbkreider@tamu.eduExerciseAndSportNutritionLab.com

hcrf.tamu.edu