Evidence map›Paper›PMID 32295624›Full record

Trial reportJournal of the International Society of Sports Nutrition2020

CYP1A2 genotype and acute effects of caffeine on resistance exercise, jumping, and sprinting performance.

Jozo Grgic, Craig Pickering, David J Bishop, Brad J Schoenfeld, Pavle Mikulic, Zeljko Pedisic

Open access · goldAbstract readRandomized Controlled Trial
PubMed Full text at PMC Publisher
In one paragraph

Trial report in Journal of the International Society of Sports Nutrition, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 34 papers, 5 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
34citing papers in PubMed, 5 pooled it
5.0field-weighted citation impact, top 4% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

34 citing papers in PubMed, 5 syntheses or guidelines pooled it, 52 citations in OpenAlex.

  1. Pooled it
  2. Pooled it
  3. Pooled it
  4. Pooled it
  5. Pooled it
  6. Acute effects of 3 and 6 mg·KgJournal of the International Society of Sports Nutrition · 2026
    Trial
  7. Trial
  8. Trial
  9. Trial
  10. Trial
  11. Trial
  12. Trial
  13. Caffeine, but not paracetamol (acetaminophen), enhances muscular endurance, strength, and power.Journal of the International Society of Sports Nutrition · 2024
    Trial
  14. Influence of the CYP1A2 c.European journal of nutrition · 2024
    Trial
  15. Trial
  16. Trial
  17. Trial
  18. Review
  19. Review
  20. Review
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

6 authors at 5 institutions in 4 countries.

Jozo GrgicInstitute for Health and Sport (IHES), Victoria University, Melbourne, Australia. jozo.grgic@live.vu.edu.au.
Craig PickeringInstitute of Coaching and Performance, School of Sport and Wellbeing, University of Central Lancashire, Fylde Road, Preston, PR1 2HE, UK.
David J BishopInstitute for Health and Sport (IHES), Victoria University, Melbourne, Australia.
Brad J SchoenfeldDepartment of Health Sciences, Lehman College, Bronx, USA.
Pavle MikulicFaculty of Kinesiology, University of Zagreb, Zagreb, Croatia.
Zeljko PedisicInstitute for Health and Sport (IHES), Victoria University, Melbourne, Australia.
Victoria University · AUEdith Cowan University · AULehman College · USUniversity of Central Lancashire · GBUniversity of Zagreb · HR

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundIt has been suggested that polymorphisms within CYP1A2 impact inter-individual variation in the response to caffeine. The purpose of this study was to explore the acute effects of caffeine on resistance exercise, jumping, and sprinting performance in a sample of resistance-trained men, and to examine the influence of genetic variation of CYP1A2 (rs762551) on the individual variation in responses to caffeine ingestion.

methodsTwenty-two men were included as participants (AA homozygotes n = 13; C-allele carriers n = 9) and were tested after the ingestion of caffeine (3 mg/kg of body mass) and a placebo. Exercise performance was assessed with the following outcomes: (a) movement velocity and power output in the bench press exercise with loads of 25, 50, 75, and 90% of one-repetition maximum (1RM); (b) quality and quantity of performed repetitions in the bench press exercise performed to muscular failure with 85% 1RM; (c) vertical jump height in a countermovement jump test; and (d) power output in a Wingate test.

resultsCompared to placebo, caffeine ingestion enhanced: (a) movement velocity and power output across all loads (effect size [ES]: 0.20-0.61; p <  0.05 for all); (b) the quality and quantity of performed repetitions with 85% of 1RM (ES: 0.27-0.85; p <  0.001 for all); (c) vertical jump height (ES: 0.15; p = 0.017); and (d) power output in the Wingate test (ES: 0.33-0.44; p <  0.05 for all). We did not find a significant genotype × caffeine interaction effect (p-values ranged from 0.094 to 0.994) in any of the analyzed performance outcomes.

conclusionsResistance-trained men may experience acute improvements in resistance exercise, jumping, and sprinting performance following the ingestion of caffeine. The comparisons of the effects of caffeine on exercise performance between individuals with the AA genotype and AC/CC genotypes found no significant differences.

trial registrationAustralian New Zealand Clinical Trials Registry. ID: ACTRN12619000885190.

Indexed as

Athletic PerformanceResistance TrainingAdultCaffeineCross-Over StudiesCytochrome P-450 CYP1A2Double-Blind MethodGenotypeHumansMalePerformance-Enhancing SubstancesSports Nutritional Physiological PhenomenaYoung AdultCaffeineCYP1A2 protein, humanCytochrome P-450 CYP1A2Performance-Enhancing SubstancesErgogenic effectsGeneticSupplementsVariation

Identifiers

PMID32295624
PMCPMC7161272
OpenAlexW3016793359

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.