Effects of two pre-workout supplements on concentric and eccentric force production during lower body resistance exercise in males and females: a counterbalanced, double-blind, placebo-controlled trial

Abstract

BackgroundPre-workout supplements purportedly enhance feelings of energy, reduce fatigue and improve exercise performance. The purpose of this study was to examine the performance effects of caffeinated and non-caffeinated multi-ingredient pre-workout supplements.MethodsIn a counterbalanced, double-blind, placebo-controlled design, eccentric and concentric force production during lower body resistance exercise on a mechanized squat device were assessed after supplement ingestion. Repetitions-in-reserve/RPE and subjective feelings of energy, focus and fatigue were also examined. Twenty-one resistance-trained adults (12 F, 9 M) completed three conditions in random order: caffeinated supplement, non-caffeinated supplement and placebo. Subjects were not informed of the presence of a placebo condition. Thirty minutes after supplement ingestion, a 3-repetition maximum test and 5 sets of 6 repetitions were completed using the squat device. Each repetition involved 4-s eccentric and concentric phases, and the force signal throughout each repetition was sampled from a load cell contained within the squat device. The scaled and filtered force signals were analyzed using customized software. Repeated measures analysis of variance and appropriate follow-up analyses were utilized to compare dependent variables, and relevant effect sizes (d) were calculated.ResultsSupplement or placebo ingestion led to similar subjective responses (p > 0.05). Energy (+8 to 44%; d = 0.3 to 0.8) and focus (+8 to 25%; d = 0.3 to 0.5) were acutely increased by supplement or placebo ingestion and decreased as the exercise session progressed. Fatigue was acutely decreased by supplement or placebo ingestion (−7 to 38%; d = −0.1 to −0.6) and increased as the exercise session progressed. Eccentric and concentric forces were unimproved by supplementation during the exercise sets for both sexes. In the non-caffeinated supplement condition only, maximal eccentric force production was lower during sets 3 to 5, as compared to set 1 (p < 0.05). Effect size data indicated that both the caffeinated and non-caffeinated supplements may contribute to small increases in concentric force production in males (+5 to 20%, d = 0.2 to 0.4 relative to placebo), but not females.ConclusionsAs compared to placebo, caffeinated and non-caffeinated multi-ingredient pre-workout supplements failed to improve concentric and eccentric force production. In males, effect size data indicate a possible small benefit of supplementation on concentric force production, although this was not statistically significant. When resistance-trained subjects were unaware of the presence of a placebo, resistance exercise performance was similar regardless of whether a placebo or multi-ingredient supplement was ingested.

Multi-ingredient pre-workout supplements, safety implications, and performance outcomes: a brief review

“… Supplement 1: Creatine (3000 mg) Betaine (2500 mg) L-Carnitine L-Tartrate (1000 mg) Rhodiola rosea extract (180 mg) Huperzine (200 mcg) c Supplement 2: BCAAs (6000 mg) Citrulline Malate (6000 mg) Creatine (2000 mg) β –Alanine (2000 mg) Betaine (1500 mg) L-Tyrosine (1500 mg) Taurine (1000 mg) N-Acetyl L-Cysteine (600 mg) Caffeine (300 mg) 30 min prior to exercise. Isokinetic squat MVC, 4 × 6 isokinetic squats ↔ Squat MVC [ 32 ] Bergstrom et al 2018 12 resistance-trained males Randomized, Double-blind, placebo-controlled, crossover design. Citrulline Malate (6000 mg) L-Leucine (4000 mg) D-Aspartic Acid (3000 mg) Creatine (2000 mg) β-alanine (1600 mg) L-Tyrosine (1200 mg) Caffeine (350 mg) 30 min prior to exercise.…”

“…Acute MIPS ingestion appears to have little effect on maximal force production (i.e, strength), though results of several recent investigations suggest that pre-exercise consumption of a caffeine-containing MIPS may help to mitigate fatigue-related decrements in force production experienced over a series of repetitions. For example, Tinsley et al [ 32 ] noted that consumption of either caffeine-free or caffeine-containing pre-workout supplements did not improve maximal concentric or eccentric force production during squatting exercise in both males and females. Collins and colleagues [ 23 ] employed a crossover design to examine the effect of a caffeine-containing ready-to-drink pre-workout beverage on bench press and leg press one-repetition maximum (1RM) and muscular endurance testing.…”

Caffeine content of pre‐workout supplements commonly used by Australian consumers

“…PWS claim to enhance exercise performance, reduce perception of fatigue, promote focus and for many, assist body fat loss. While only a few studies have been conducted to determine the efficacy of PWS on strength and power, isolated ingredients such as caffeine have received considerable scientific attention, indicating likely ergogenic effects . As such, many PWS promote the inclusion of caffeine as a primary active ingredient.…”

Current perspectives of caffeinated energy drinks on exercise performance and safety assessment

“…2,[7][8][9] Additionally, acute ingestion of caffeine has been reported to enhance high-intensity intermittent exercise capacity. [10][11][12][13][14] Therefore, there is rationale for athletes to use EDs and/or ESs prior to and/or during exercise simply as a convenient way to ingest caffeine.…”