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Table 1 Studies included in the analysis: summary of study designs

From: Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis

Study

Study design

Participants age (years)

Sample size and sex

Resistance/sport training experience

Habitual caffeine intake (mg.d−1)a

Caffeine form

Caffeine dosage (mg.kg−1)

Timing of caffeine ingestion before the experimental session(s) [minutes])

Exercise(s) used for the muscle strength/power assessment

PEDro score

Ali et al. [7] 2016

RDB

24 ± 4

10 females

Athletes

0–300

Capsule

6

60

CMJ

10

Andrade-Souza et al. [22] 2014

RDB

25 ± 3

11 males

Athletes

N/A

Capsule

6

60

CMJ

8

Arazi et al. [12] 2016a

RDB

17 ± 1

10 females

Untrained/ Athletes

<  60

Capsule

2 and 5

60

LP and ST

10

Arazi et al. [11] 2016b

RDB

21 ± 4

15 males

Untrained

N/A

Capsule

6

60

BP and LP

10

Astorino et al. [3] 2008

RDB

23 ± 4

22 males

Trained

110 ± 152

Capsule

6

60

BP and LP

10

Bloms et al. [8] 2016

RSB

20 ± 1

9 females

Athletes

N/A

Capsule

5

60

CMJ and SJ

8

21 ± 2

16 males

Brooks et al. [13] 2015

RDB

21 ± 3

14 males

Untrained

N/A

Capsule

5

60

MBS

10

Clarke et al. [23] 2016

RDB

21 ± 2

8 males

Athletes

N/A

Capsule

3

60 and during the testing sessions

CMJ

10

Diaz-Lara et al. [15] 2016

RDB

29 ± 3

14 males

Trained/ Athletes

<  60

Capsule

3

60

BP and CMJ

10

Foskett et al. [24] 2009

RDB

24 ± 5

12 males

Athletes

0–350

Liquid

6

60

CMJ

10

Gant et al. [25] 2010

RDB

21 ± 3

15 males

Athletes

N/A

Liquid

260 (fixed) 3.7 on average

60 and during the testing sessions

CMJ

10

Gauvin [26] 2016

RDB

22 ± 2

23 males

Untrained/ Non-athletes

< 200 per week

Capsule

7

60

CMJ

9

Goldstein et al. [5] 2010

RDB

25 ± 7

15 females

Trained

<  250 (n = 8)

>  250 (n = 7)

Liquid

6

60

BP

10

Grgic et al. [4] 2017

RDB

26 ± 6

17 males

Trained/ Non-athletes

58 ± 92

Liquid

6

60

BP, BBS and ST

9

Martin [16] 2015

RDB

20 ± 1

12 males

Trained

N/A

Gel

75 (fixed) - 0.9 on average

60

BP and BBS

10

Sabblah et al. [14] 2015

RSB

24 ± 3

7 females

Trained

N/A

Liquid

5

60

BP and MBS

8

28 ± 6

10 males

Williams et al. [6] 2008

RDB

26 ± 4

9 males

Trained

‘Low’ (no exact values)

Capsule

300 (fixed) - 3.6 on average

45

BP and LPD

10

  1. aintake per day unless stated otherwise; RDB randomized double-blind study, RSB randomized single-blind study, CMJ countermovement jump, SJ squat jump, LP leg press, ST Sargent test, BP bench press, MBS machine-based squat, LPD lat pulldown, BBS barbell back squat