Table 2 Overview of the included studies, with participants characteristics, mental fatigue task aspects and overall effects on endurance performance. Effects on endurance performance attributed to mental fatigue are highlighted in bold

Brietzke et al. [79]

N: 20 cyclists (♂)

Age: 35.00 ± 7.00 y

Mass: 80.50 ± 10.40 kg

Height: 176.00 ± 5.00 cm

BMI: 26.04 ± 2.94 kg/m²

Level: PL 2/3 (PPO = 358.63 ± 21.96 W, YoE = 7.56 ± 5.89 y, TV = 310.6 ± 128.1 km/week)

RVIP test (PC)

–

40 min

S: MF ↑ in I₂ vs I₁ (assessed using M-VAS)

B: ↓ in RT and ACC in I₂ vs I₁ (assessed during RVIP)

P: ↑ θ band activity in I₂ vs I₁ (assessed using EEG)

↓ in TTE (small) and PPO (small) in I vs Baseline, no effects on VO₂Peak or VT (measured using a MIET) (ES(d))

Campos et al. [29]

N: 13 judo athletes (9♂/4♀)

Age: 19.50 ± 3.00 y

Mass: 68.10 ± 13.30 kg

Height: 169.00 ± 5.10 cm

Body fat: 12.20 ± 3.80%

Level: NA (YoE = 7.20 ± 3.90 y; TL = 11.20 ± 4.60 h/wk)

Incongruent Stroop task with RI (paper version)

Docu

30 min

S: MF ↑ in I₂ vs I₁ and in I₂ vs C₂ (assessed using M-VAS)

No significant effects on number of throws (trivial) or physical performance index (small) (measured using a specific judo fitness test)

Clark et al. [33]

(1) Competitive group:

N: 10 competitive athletes (♂)

Age: 27.40 ± 6.30 y

Mass: 75.60 ± 9.70 kg

Height: 179.00 ± 6.00 cm

Level: PL3 (VO₂ peak = 58.30 ± 4.10 mL/kg.min; PPO = 401.00 ± 36.00 W; W_get = 149.00 ± 32.00; TL = 9.50 ± 2.50 h/week; PA-R = 9.70 ± 0.70; TET = 9.50 ± 2.50 h/week)

(2) Non-competitive group:

N: 10 healthy participants (♂)

Age: 25.80 ± 4.60 y

Mass: 93.30 ± 17.00 kg

Height: 183.00 ± 6.00 cm

Level: PL1 (VO₂ peak = 39.00 ± 7.30 ml/kg.min; PPO = 280.00 ± 27.00 W; W_get = 91.00 ± 25.00 W; TL = 3.20 ± 1.90 h/week; PA-R = 3.80 ± 1.90; TET = 3.20 ± 1.90 h/week)

Modified (congruent, incongruent and neutral) Stroop task and N-back task (PC)

Docu

30 min

B: No effects on ACC or RT in both groups (assessed during the intervention tasks)

P: No effects on cerebral oxygenation in both groups (assessed using fNIRS)

No evidence of MF based on manipulation checks

Filipas et al. [68]

N: 18 rowers (11♂/6♀)

Age: 11.00 ± 1.06 y

Mass: 46.72 ± 11.14 kg

Height: 154.79 ± 9.41 cm

Level: NA (TF: > 2 sessions/week; YoE; 1.50 ± 0.85 y)

(1) Incongruent Stroop task (PC)

(2) Customised arithmetic test (Paper)

Drawing a mandala

60 min

B: no effects on RT, ↑ in ACC in I₆ vs I₁ (assessed during the Stroop task)

No evidence of MF based on manipulation checks

Filipas et al. [69]

N: 10 U23 cyclists (♂)

Age: 20.00 ± 1.20 y

Mass: 66.10 ± 7.60 kg

Height: 180.40 ± 5.60 cm

Level: PL4 (calc.) (VO₂Max = 69.00 ± 4.40 ml/min.kg; PPO = 380.00 ± 39.00 W; TF > 4 sessions/week; TL > 300 h/week; YoE > 3 y)

Modified (congruent and incongruent) Stroop task (PC)

Docu

30 min

B: no effects on RT and ACC (assessed during Stroop task)

P: no effects on HRV (assessed using a Polar T61)

No evidence of MF based on manipulation checks

Filipas et al. [35]

(1) U14 group:

N: 12 soccer players U14 (♂)

Mass: 55.00 ± 8.00 kg

Height: 168.00 ± 4.00 cm

Level: NA (Exp = competing at national level; YoE > 3 y)

(2) U16 group:

N: 12 soccer players U16 (♂)

Mass: 62.00 ± 8.00 kg

Height: 170.00 ± 5.00 cm

Level: NA (Exp = competing at national level; YoE > 3 y)

(3) U18 group:

N: 12 soccer players U18 (♂)

Mass: 69.00 ± 8.00 kg

Height: 177.00 ± 7.00 cm

Level: NA (Exp = competing at national level; YoE > 3 y)

Incongruent Stroop task (PC)

Reading a selection of emotionally neutral online magazines

I: 30 min

C: 15 min

S: MF ↑ in I vs C (assessed using M-VAS)

B: No effects on ACC and RT (assessed during Stroop task)

↓ in test distance (small to large) in I vs C in all age groups (measured using the Yo-Yo IR test) (ES(d))

Filipas et al. [32]

(1) Training group:

N: 10 participants (3♂/7♀)

Age: 27.60 ± 6.30 y

Mass: 69.60 ± 18.40 kg

Height: 169.40 ± 6.80 cm

Level: PL1 (calc.) (VO₂peak = 32.90 ± 6.90 ml/min.kg)

(2) Placebo group:

N: 10 participants (3♂/7♀)

Age: 27.50 ± 6.00 y

Mass: 68.70 ± 14.30 kg

Height: 169.50 ± 9.60 cm

Level: PL1 (calc.) (VO₂peak = 32.80 ± 5.60 ml/min.kg)

(1) Cognitive test battery (45 min)

(2) Modified Stroop task (40 min)

(3) task switching (5 min)

Staring at a white screen

I: 90 min

C: 15 min

S: MF ↑ in I vs C (assessed using M-VAS)

↓ in total distance (small) in I vs C in both groups (measured using a time-based time trial) (ES(d))

Fortes et al. [87]

N: 25 swimmers (14♂/11♀)

Age: 20.40 ± 2.06 y

Mass: 72.00 ± 9.00 kg

Height: 181.00 ± 7.00 cm

Level: NA (TF = 5.80 ± 0.50 sessions/week; TL = 42.50 ± 6.20 km/week; YoE =  ~ 8.40 y; FINApoints = 602.61 ± 25.78 (♂)/611.84 ± 26.61 (♀); Exp = international-level)

Smartphone use (Social networking apps)

Docu

30 min

S: MF ↑ in I vs C and in I₁ vs I₂ (assessed using M-VAS)

B: no effect on ACC, ↑ in RT in I vs C (assessed using a short Stroop task)

P: no effects on HRV (assessed using a Polar H10)

↑ in completion time (medium) in I vs C (mostly visible in the second block) (assessed using a 200 m (distance based) swimming trial) (ES(η²))

Franco- Alvarenga et al. [67]

N: 12 cyclists (?)

Age: 34.30 ± 6.20 y

Mass: 77.60 ± 6.80 kg

Height: 179.30 ± 5.10 cm

Level: PL3 (VO₂Max = 58.90 ± 6.20 mL/kg.min; PPO = 367.00 ± 32.50 W; TF = 4.70 ± 2.30 sessions/wk; TL = 283.70 ± 138.60 km/wk; Experience =  ~ 6.50 y)

Caffeine consumption: non-consumers (≤ 40 mg/day) = 3; occasional consumers (≤ 250 mg/day) = 5; daily consumers (between 250 and 572 mg/day) = 4

RVIP test (PC)

–

40 min

S: MF ↑ in I₂ vs I₁ (assessed using M-VAS)

P: ↑ in θ activity in I₂ vs I₁ (assessed using EEG)

↑ in completion time (very large) and ↓ in APO (very large) in I vs C (assessed using a distance based time trial) (ES(d))

Holgado et al. [77]

N: 30 participants (24♂/6♀)

Age: 23.50 ± 6.30 y

Level: PL1 (calc.) (VO₂max: 41.88 ± 9.08 ml/min.kg)

AX-CPT (PC)

Documentary

90 min

S: MF ↑ in I vs C (assessed using M-VAS)

B: no effects on ACC (assessed during the AX-CPT task)

No effects on a TTE (assessed using a 80% VO₂ Max TTE test)

Lam et al. [76] study 1

N: 9 participants (♂)

Age: 22.00 ± 2.60 y

Mass:70.00 ± 7.50 kg

Height: 173.00 ± 2.00 cm

Incongruent Stroop task

/

30 min

S: MF ↑ in I vs Baseline (assessed using M-VAS)

↓ in distance covered (small) in I vs Baseline (assessed using a Yo-Yo IR1 test) (ES(d))

Lam et al. [76] study 2

N: 9 participants (7♂/2♀)

Age: 21.10 ± 1.20 y

Mass:74.00 ± 8.50 kg

Height: 179.00 ± 4.00 cm

Incongruent Stroop task

–

30 min

S: MF ↑ in I vs Baseline (assessed using M-VAS)

↑ in completion time (small) in I vs Baseline (assessed using a distance based time trial) (ES(d))

Lopes et al. [36]

(1) Male group:

N: 18 runners (♂)

Age: 25.00 ± 1.00 y

Mass: 63.20 ± 1.30 kg

Height: 172.70 ± 1.50 cm

Level: PL5 (calc.) (IAAF score = 846.00 ± 49.00; TF = 8 sessions/wk; TL = 12 ± 1 km/session or 96 ± 9 km/week; RE = 215.00 ± 4.00 ml/kg.km; VO₂Max = 73.24 ± 1.37 ML/kg.min; maxHR = 191.00 ± 2.00; MaxSpeed = 21.90 ± 0.30 km/h; V_E = 160.00 ± 4.20 l/min)

(2) Female group:

N: 17 runners (♀)

Age: 25.00 ± 1.00 y

Mass: 52.40 ± 1.00 kg

Height: 163.80 ± 1.20 cm

Level: PL5 (calc.) (IAAF score = 867.00 ± 36.00; TF = 7 sessions/wk; TL = 12 ± 1 km/session or 88 ± 7 km/week; RE = 229.00 ± 4.00 ml/kg.km; VO₂Max = 61.29 ± 1.45 mL/kg.min; maxHR = 186.00 ± 2.00; MaxSpeed = 18.80 ± 0.30 km/h; V_E = 112.00 ± 2.40 l/min)

Stroop task (PC)

Docu

45 min

S: MF ↑ in I₂ vs C₂ and in I₂ vs I₁ in both groups (assessed using M-VAS)

B: no effects on RT and ACC (assess using a shorter and distinct Stroop task)

↓ in TTE (small) in I vs C in both groups (measured using a running TTE test) (ES(d))

Macmahon et al. [3]

N: 20 participants (18♂/2♀)

Age: 25.40 ± 3.24 y

Level: NA (TF = 2.84 ± 1.79 h/week)

AX-CPT

Docu

90 min

B: no difference in I vs C (assessed using AX-CPT)

No evidence of MF based on manipulation checks

Macmahon et al. [71]

N: 13 participants (10♂/3♀)

Age: 19.92 ± 1.75 y

Level: NA (TL = 3.55 ± 1.44 sessions/week; TF = 6.72 ± 4.03 h/week; YoE = 10.80 ± 4.48 y; Exp = registered recreational leagues or higher)

Incongruent Stroop task (PC)

Congruent Stroop task

30 min

S: MF ↑ in I₂ vs C₂ and in I₂ vs I₁ (assessed using a 7-pt Likert scale)

B: ↑ in RT in I vs C, no effect on ACC (assessed during the Stroop tasks)

↓ in duration time (medium) in I vs C (measured using a beep test) (ES(η²_p))

Marcora et al. [78]

N: 16 subjects (10♂/6♀)

Age: 26.00 ± 3.00 y

Mass: 69.00 ± 10.00 kg

Height: 175.00 ± 9.00 cm

Level: PL2 (calc.) (PPO = 288.00 ± 70.00 W; VO2peak = 52.00 ± 8.00 ml/kg.min)

AX-CPT

Docu

90 min

B: ↓ in ACC (assessed during the AX-CPT)

P: no effect on glucose (assessed using a Physioflow PF05L1)

↓ in TTE (small) in I vs C, no effects on RPM (assessed using a TTE test) (ES(d))

Martin et al. [31]

(1) Elite group (EG)

N: 8 cyclists (♂)

Age: 23.40 ± 6.40 y

Mass: 68.20 ± 4.30 kg

Height: 180.00 ± 7.00 cm

Level: PL5 (PPO: 414.00 ± 48.00 W; TL > 5 sessions/week; TV > 500 km/week; YoE > 5y)

(2) Non-elite group (NEG)

N: 9 participants (♂)

Age: 25.60 ± 5.30 y

Mass: 80.70 ± 11.30 kg

Height: 177.00 ± 7.00 cm

Level: PL1/2 (PPO: 261.00 ± 28.00 W; TL ~ 3 sessions/week; TV ~ 80 km/week; YoE = 2 y)

Modified incongruent Stroop task (PC)

Sitting and focussing on a centred black cross

I: 30 min

C: 10 min

B: ↓ in RT with no effects on ACC (assessed during the Stroop task)

No evidence of MF based on manipulation checks

O’Keeffe et al. [81]

N: 15 active participants (♂)

Age: 24.00 ± 3.00 y

TDLoadDback

Resting

I: 16 min

C: 2 min

S: MF ↑ in I₁ vs I₂ (assessed using VAS)

No performance effects (PPO, APO and oxygen consumption) in I vs C (assessed using a time-based time trial)

Pageaux et al. [72]

N: 12 adults (8♂/ 4♀)

Age: 21.00 ± 1.00 y

Mass: 69.00 ± 11.00 kg

Height: 174.00 ± 12.00 cm

Level: PL2 (TF ≥ 2 aerobic activities/week)

Modified incongruent Stroop task (PC)

Congruent Stroop task (PC)

30 min

B: ↑ in RT in I vs C, no effect on ACC (comparison of Stroop task responses)

P: no effect on glucose (assessed using Biosen EFK Diagnostics)

↑ in completion time (medium) and ↓ in running speed (medium) in I vs C, no effect on pacing (measured using a 5 km running time trial) (ES(η²_p))

Penna et al. [84]

N: 16 swimmers (11♂/ 5♀)

Age: 15.45 ± 0.51 y

Level: NA (TL = 30,000 m/week; YoE = 7.35 ± 2.20 y; Exp = competing in state and national competitions)

Stroop task (paper version)

Docu

30 min

S: MF ↑ in I₂ vs I₁ and in I vs C (assessed using M-VAS)

P: no effect on HRV (assessed using a polar V800)

↑ in completion time (trivial), ↓ in mean speed (trivial) and impaired pacing (trivial) in I vs C (measured using a 1500 m swimming task) (ES(d))

Penna et al. [83]

N: 12 handball players (?)

Age: 17.50 ± 3.63 y

Level: NA (TL =  ~ 6 h/week; YoE = 5.00 ± 2.20 y; Exp = regional level)

Stroop task (paper version)

Docu

30 min

S: MF ↑ in I₂ vs I₁ and in I₂ vs C₂ (assessed using M-VAS)

↓ in total distance covered (small) in I vs C (measured using the Yo-Yo IR1) (ES(d))

Pires et al. [80]

N: 8 cyclists (♂)

Age: 29.30 ± 7.90 y

Mass: 67.60 ± 7.50 kg

Height: 177.20 ± 4.60 cm

Level: PL3 (calc.) (PPO = 318.90 ± 22.40 W; VO₂Max = 64.10 ± 4.80 ml/kg.min; YoE = 5.00 ± 3.20 y; Exp = competing at regional level)

RVIP test (PC)

Rest

30 min

B: ↑ in errors and ↓ in ACC, no effects on RT (assessed during RVP test)

P: ↑ in θ PFC power in I_1,2,3 vs C_1,2,3 (blocks during RVP test) (assessed using EEG)

↑ in time to completion (moderate) and ↓ in APO (moderate) in I vs C (measured using a cycling time trial) (ES(d))

Salam et al. [73]

N: 11 cyclists (♂)

Age: 38.00 ± 6.00 y

Mass: 76.50 ± 9.60 kg

Level: PL3 (calc.) (VO2peak = 60.50 ± 4.10 ml/kg.min; TL > 5 h of training/week; YoE ≥ 3y)

Modified Stroop task (PC)

Reading magazines

30 min

S: MF ↑ in I₂ vs C₂ (assessed using a 10 pt Likert scale)

↓ in TTE (small to moderate) and estimated W’ (moderate) in I vs C, no effects on CP (measured using a TTE test) (ES(d))

Schücker et al. [74]- study 1

N: 12 sport/endurance athletes (3♂, 9♀)

Age: 29.41 ± 14.47 y

Level: NA (TF = 5.87 ± 3.52 sessions/week; TL = 8.25 ± 4.31 h/week; YoE = 10.00 ± 7.35y)

Unmatched Stroop task (PC)

Matched Stroop task (PC)

10 min

S: MF ↑ in I vs C (assessed using a Likert scale)

B: ↑ in RT and ↓ in ACC in I vs C (assessed during the Stroop task)

P: no effect on glucose (assessed using Accu-Chek performa meter)

No effects on running time in I vs C (measured using a beep test)

Schücker et al. [74]- study 2

N: 14 sport/endurance athletes (5♂, 9♀)

Age: 30.64 ± 13.11 y

Level: NA (TF = 5.04 ± 2.77 sessions/week; TL = 7.89 ± 4.16 h/week; YoE = 14.54 ± 8.65y)

Unmatched Stroop task (PC)

Matched Stroop task (PC)

10 min

S: MF ↑ in I vs C (assessed using a Likert scale)

B: ↑ in RT and ↓ in ACC in I vs C (assessed during the Stroop task)

No effects on running time in I vs C (measured using a beep test)

Slimani et al. [85]

N: 10 active endurance athletes (♂)

Age: 16.00 ± 1.05 y

Mass: 55.50 ± 4.20 kg

Height: 1.62 ± 0.04 cm

Level: PL1 (calculated based on performance parameters) (VO₂ Max = 39.20 ± 4.80 ml/min/kg; Exp = “engaged in track events”)

Stroop task (paper version)

Reading magazines

30 min

B: ↓ in concentration performance and ↑ in errors in I₂ vs C₂ (assessed using the d2 test)

↓ in estimated (moderate) and speed related (moderate) VO₂Max values in I vs C (measured using a beep test) (ES(d))

Smith et al. [86]

N: 12 soccer players (♂)

Age: 24.00 ± 0.40 y

Mass: 76.10 ± 2.00 kg

Height: 175.30 ± 1.30 cm

Level: NA (Exp = recreational)

Modified Stroop task (paper version)

Reading emotionally neutral magazines

30 min

S: MF ↑ in I₂ vs C₂ (assessed using M-VAS)

↓ in total distance (small) (measured using the Yo-Yo IR1) (ES(d))

Veness et al. [75]

N: 10 cricket players (♂)

Age: 21.00 ± 8.00 y

Mass: 77.10 ± 9.90 kg

Height: 1.85 ± 0.08 m

Level: NA (Exp = “elite”; YoE ≥ 2 y)

Modified Stroop task (PC)

Reading emotionally neutral magazines

30 × 60 s Stroop

S: MF ↑ in I vs C (assessed using M-VAS)

↓ in total distance (small) (measured using the Yo-Yo IR1) (ES(d))

Weerakoddy et al. [70]

N: 25 Australian football players (♂)

Age: 23.80 ± 4.60 y

Level: NA (Exp = community level)

Incongruent Stroop task (app)

Documentary

I: 35 min

C: 30 min

B: ↓ in test score in I₁ vs I₃₀ (assessed during Stroop)

↓ in total distance (small) (measured using the Yo-Yo IR1) (ES(d))

Zering et al. [82]

N: 15 university students (8♀/7♂)

Age: 19.56 ± 1.69

Level: PL 1 (Frequency of PA = 6.00 ± 2.00 sessions (> 10 min)/week)

Stop signal task (PC)

Documentary

10.5 min

S: MF ↑ in I₂ vs C₂ (assessed using ME Borg scale)

↓ in PPO (medium) and VO₂Peak (moderate) in I vs C (measured using a graded exhaustion test) (ES(η²_p + d))