Table 3 Summary of reliability data from the included studies

Amarante do Nascimento et al. [21]

Chest press: 0.95–97

Biceps curl machine: 0.95–97

Knee extension: 0.95–97

Unclear

Not presented

Chest press: 0.6 kg

Biceps curl machine: 0.5 kg

Knee extension: 1.2 kg

Augustsson et al. [22]

Knee extension (men): 0.93

Knee extension (women): 0.93

2,1

Knee extension (men): 7.8%

Knee extension (women): 6.4%

↔ in any exercise

Augustsson et al. [23]

Inter-rater

Bench press: 0.98 (95% CI: 0.94–0.99)

Back squat: 0.85 (95% CI: 0.40–0.95)

2,1

Not presented

Bench press: ↔

Back squat: 6.8 kg

Barbalho et al. [26]^a

Before 12 weeks of training

Bench press: 0.99

Leg press: 0.99

After 12 weeks of training

Bench press: 0.99

Leg press: 0.99

Unclear

Before 12 weeks of training

Bench press: < 1%

Leg press: < 1%

After 12 weeks of training

Bench press: < 1%

Leg press: < 1%

n/a

Benton et al. [24]

Chest press: 0.95 (95% CI: 0.90–0.98)

Leg press: 0.95 (95% CI: 0.89–0.98)

Unclear

Not presented

Chest press: ↔

Leg press: 6.9 ± 0.6 kg

Benton et al. [25]^a

Before 8 weeks of training

Chest press: 0.98

Leg press: 0.99

After 8 weeks of training

Chest press: 0.97

Leg press: 0.99

Unclear

Not presented

↔ in any exercise

Buckley and Hass [16]

Chest press: 0.95 (95% CI: 0.90–0.98)

Biceps curl machine: 0.97 (95% CI: 0.92–0.98)

Knee extension: 0.96 (95% CI: 0.93–0.97)

Knee flexion: 0.91 (95% CI: 0.79–0.96)

“2-way random-effects”

Not presented

Chest press: ↔

Biceps curl machine: 2.7 kg (95% CI: 1.2–4.1 kg)

Knee extension: 4.0 kg (95% CI: 1.9–6.2 kg)

Knee flexion: 2.4 kg (95% CI: 0.2–4.7 kg)

Carabello et al. [27]

Knee extension: 0.80

“2-way fixed-model”

Not presented

n/a

Comfort and McMahon [28]

Back squat (men): 0.99

Back squat (women): 0.97

Power clean (men): 0.99

Power clean (women): 0.99

“2-way random-effects”

Not presented

↔ in any exercise

Ellis et al. [29]

Intra-rater

Leg press: 0.96 (95% CI: 0.81–1.00)

Inter-rater

Leg press: 0.93 (95% CI: 0.83–0.97)

2,1

Not presented

n/a

Faigenbaum et al. [30]

Power clean: 0.98 (95% CI: 0.96–0.99)

2,k

Not presented

Power clean: ↔

García-Ramos et al. [31]

Bench press: 0.98 (95% CI: 0.96–0.99)

Unclear

Bench press: 1.9% (95% CI: 1.5–2.5%)

Bench press: ↔

Grosicki et al. [32]

Biceps curl (older women): 0.90

Biceps curl (young women): 0.93

Biceps curl (older men): 0.96

Biceps curl (young men): 0.98

Leg press (older women): 0.99

Leg press (young women): 0.97

Leg press (older men): 0.98

Leg press (young men): 0.99

Knee extension (older women): 0.91

Knee extension (young women): 0.97

Knee extension (older men): 0.98

Knee extension (young men): 0.94

“1-way random model”

Not presented

Biceps curl (older women): 1.1 kg

Biceps curl (young women): 1.4 kg

Biceps curl (older men): 1.0 kg

Biceps curl (young men): ↔

Leg press (older women): 6.1 kg

Leg press (young women): 17.5 kg

Leg press (older men): 9.3 kg

Leg press (young men): 10.8 kg

Knee extension (older women): 2.0 kg

Knee extension (young women): 2.5 kg

Knee extension (older men): 2.3 kg

Knee extension (young men): 8.5 kg

Hageman et al. [33]

Bench press: 0.94

Knee extension: 0.91

3,1

Not presented

n/a

LeBrasseur et al. [34]

Chest press (young men): 0.99 (95% CI: 0.99–1.00)

Chest press (older men): 0.98 (95% CI: 0.96–0.99)

Chest press (older men with mobility limitations): 0.98 (95% CI: 0.96–0.99)

Leg press (young men): 0.98 (95% CI: 0.97–0.99)

Leg press (older men): 0.95 (95% CI: 0.88–0.98)

Leg press (older men with mobility limitations): 0.98 (95% CI: 0.96–0.99)

“2-way

mixed-model for repeated measures”

Not presented

↔ in any exercise

Levinger et al. [18]

Chest press: 0.99

Lat pull down: 0.99

Triceps extension: 0.98

Biceps curl: 0.98

Seated row: 0.99

Leg press: 0.99

Knee extension: 0.97

2,1

Chest press: 6.5% (95% CI: 5.4–8.1%)

Lat pull down: 3.4% (95% CI: 2.8–4.2%)

Triceps extension: 5.3% (95% CI: 4.4–6.6%)

Biceps curl: 7.2% (95% CI: 6.0–7.6%)

Seated row: 3.4% (95% CI: 2.8–4.2%)

Leg press: 3.3% (95% CI: 2.8–4.1%)

Knee extension: 6.0 (95% CI: 6.0–9.0)

Chest press: ↔

Lat pull down: ↔

Triceps extension: ↔

Biceps curl: ↔

Seated row: ↔

Leg press: 3.3 kg

Knee extension: ↔

McCurdy et al. [35]

Unilateral squat (untrained men): 0.99

Unilateral squat (untrained women): 0.97

Unilateral squat (trained men): 0.98

Unilateral squat (trained women): 0.99

Unclear

Not presented

Unilateral squat (untrained men): 2.8 ± 3.2 kg

Unilateral squat (untrained women): 1.8 ± 2.6 kg

Unilateral squat (trained men): 7.1 ± 3.8 kg

Unilateral squat (trained women): 1.1 ± 1.5 kg

McCurdy et al. [36]

Chain loaded bench press (men): 0.99

Chain loaded bench press (women): 0.93

Unclear

Chain loaded bench press (men): 1.4%

Chain loaded bench press (women): 3.5%

Chain loaded bench press (men): 2.6 kg

Chain loaded bench press (women): ↔

Neto et al. [37]

Bench press: 0.97

Lat pull down: 0.93

Triceps extension: 0.96

Biceps curl: 0.94

Knee extension: 0.92

Knee flexion: 0.99

Leg press: 0.96

Half-squat: 0.91

“2-way random

model, consistency option, single measures”

Not presented

↔ in any exercise

Patterson et al. [38]

Chest press (men): 0.96

Chest press (women): 0.98

Lat pull down (men): 0.92

Lat pull down (women): 0.98

Shoulder press (men): 0.98

Shoulder press (women): 0.97

Knee extension (men): 0.74

Knee extension (women): 0.97

Leg press (men): 0.69

Leg press (women): 0.91

Unclear

Not presented

↔ in any exercise

Phillips et al. [39]

Not presented

n/a

Bench press (men): 5.4% (95% CI: 4.0–8.7%)

Bench press (women): 5.2% (95% CI: 4.3–7.3%)

Leg press (men): 6.7%

(95% CI: 5.1–10.9%)

Leg press (women): 6.3%

(95% CI: 5.1–10.9%)

Bench press (men): 4.9 kg

Bench press (women): ↔

Leg press (men): ↔

Leg press (women): ↔

Ribeiro et al. [40]

Bench press (men): 0.96

Bench press (women): 0.97

Biceps curl (men): 0.98

Biceps curl (women): 0.98

Smith machine squat (men): 0.77

Smith machine squat (women): 0.89

Unclear

Bench press (men): 6.5%

Bench press (women): 5.6%

Biceps curl (men): 4.1%

Biceps curl (women): 5.3%

Smith machine squat (men): 12.1%

Smith machine squat (women): 8.0%

Bench press (men): 2.5 kg

Bench press (women): ↔

Biceps curl (men): ↔

Biceps curl (women): ↔

Smith machine squat (men): 10 kg

Smith machine squat (women): ↔

Ribeiro et al. [41]

Bench press (novice): 0.99

Bench press (intermediate): 0.98

Bench press (advanced): 0.97

Biceps curl (novice): 0.97

Biceps curl (intermediate): 0.98

Biceps curl (advanced): 0.96

Smith machine squat (novice): 0.95

Smith machine squat (intermediate): 0.93

Smith machine squat (advanced): 0.95

Unclear

Bench press (novice): 2.7%

Bench press (intermediate): 4.1%

Bench press (advanced): 3.4%

Biceps curl (novice): 3.8%

Biceps curl (intermediate): 3.8%

Biceps curl (advanced): 3.5%

Smith machine squat (novice): 5.4%

Smith machine squat (intermediate): 6.5%

Smith machine squat (advanced): 6.3%

Bench press (novice): 2.2 kg

Bench press (intermediate): 3.5 kg

Bench press (advanced): 3.2 kg

Biceps curl (novice): 1.8 kg

Biceps curl (intermediate): 2.1 kg

Biceps curl (advanced): 2.0 kg

Smith machine squat (novice): 8.6 kg

Smith machine squat (intermediate): 10.9 kg

Smith machine squat (advanced): 9.9 kg

Rydwik et al. [42]

Shoulder press (untrained): 0.97

Shoulder press (trained): 0.97

Unclear

Not presented

Shoulder press (untrained): 1.3 kg (95% CI: 0.1–2.5 kg)

Shoulder press (trained): 1.7 kg (95% CI: 0.5–2.4 kg)

Salem et al. [43]

Leg press: 0.98

Knee extension: 0.98

Knee flexion: 0.96

Ankle plantar flexion: 0.97

Cronbach’s alpha

Ankle plantar flexion: 6.0%

Leg press: 9.1 kg

Knee extension: ↔

Knee flexion: 2.7 kg

Ankle plantar flexion: 3 kg

Schroeder et al. [44]^b

Chest press (cohort 1): 0.94

Chest press (cohort 2): 0.91

Lat pull down (cohort 1): 0.91

Lat pull down (cohort 2): 0.92

Leg press (cohort 1): 0.90

Leg press (cohort 2): 0.96

Knee extension (cohort 1): 0.88

Knee extension (cohort 2): 0.98

Knee flexion (cohort 1): 0.84

Knee flexion (cohort 2): 0.93

Unclear

Chest press (cohort 1): 5.3%

Chest press (cohort 2): 7.9%

Lat pull down (cohort 1): 5.9%

Lat pull down (cohort 2): 4.4%

Leg press (cohort 1): 6.3%

Leg press (cohort 2): 4.2%

Knee extension (cohort 1): 9.0%

Knee extension (cohort 2): 4.7%

Knee flexion (cohort 1): 7.8%

Knee flexion (cohort 2): 7.0%

Chest press (cohort 1): ↔

Chest press (cohort 2): ↔

Lat pull down (cohort 1): ↔

Lat pull down (cohort 2): ↔

Leg press (cohort 1): ↔

Leg press (cohort 2): ↔

Knee extension (cohort 1): 3 ± 7

Knee extension (cohort 2): 3 ± 4

Knee flexion (cohort 1): ↔

Knee flexion (cohort 2): ↔

Scott et al. [45]

Harness back squat: 0.98 (95% CI: 0.93, 0.99)

Unclear

Harness back squat: 2.6% (95% CI: 1.9–4.3%)

Harness back squat: ↔

Seo et al. [46]

Bench press (men): 1.00

Bench press (women): 1.00

Lat pull down (men): 0.98

Lat pull down (women): 1.00

Shoulder press (men): 0.64

Shoulder press (women): 1.00

Triceps extension (men): 1.00

Triceps extension (women): 1.00

Seated row (men): 0.84

Seated row (women): 1.00

Biceps curl (men): 0.99

Biceps curl (women): 1.00

Leg press (men): 1.00

Leg press (women): 1.00

Squat (men): 0.99

Squat (women): 0.97

Knee extension (men): 1.00

Knee extension (women): 0.99

Knee flexion (men): 1.00

Knee flexion (women): 0.99

Hip flexion (men): 0.97

Hip flexion (women): 1.00

Hip extension (men): 1.00

Hip extension (women): 1.00

Unclear

Bench press (men): 2.9%

Bench press (women): 5.4%

Lat pull down (men): 2.1%

Lat pull down (women): 4.4%

Shoulder press (men): 2.2%

Shoulder press (women): 4.4%

Triceps extension (men): 3.0%

Triceps extension (women): 5.5%

Seated row (men): 2.3%

Seated row (women): 4.8%

Biceps curl (men): 3.3%

Biceps curl (women): 6.4%

Leg press (men): 2.4%

Leg press (women): 3.2%

Squat (men): 3.5%

Squat (women): 5.3%

Knee extension (men): 1.6%

Knee extension (women): 3.1%

Knee flexion (men): 1.2%

Knee flexion (women): 3.3%

Hip flexion (men): 1.7%

Hip flexion (women): 3.1%

Hip extension (men): 0.5%

Hip extension (women): 2.0%

↔ in any exercise

Sugiura et al. [47]

Intra-rater

Knee extension: 0.99

Inter-rater

Knee extension: 0.98

1,1 and 2,1

Not presented

n/a

Tagesson and Kvist [48]

Intra-rater

Squat: 0.64

Knee extension: 0.90

Inter-rater

Squat: 0.94

Knee extension: 0.96

2,1

Not presented

Intra-rater

Squat: ↔

Knee extension: ↔

Inter-rater

Squat: 4.2 ± 7.3 kg

Knee extension: ↔

Tiggemann et al. [49]

Bench press (untrained men): 0.99

Bench press (recreationally active men): 0.99

Bench press (trained men): 1.00

Leg press (untrained men): 0.93

Leg press (recreationally active men): 0.97

Leg press (trained men): 0.92

Unclear

Not presented

Bench press (untrained men): 1.2 kg

Bench press (recreationally active men): 0.6 kg

Bench press (trained men): 1.4 kg

Leg press (untrained men): 7 kg

Leg press (recreationally active men): 5.5 kg

Leg press (trained men): 14.9 kg

Urquhart et al. [50]

Single leg squat: 0.99 (0.96–1.00)

Unclear

1.6% (1.1–2.6%)

Single leg squat: 2.1 kg