Table 1.
Summary of the selected studies
| Study | Sample characteristics | Competitive level | TID % (Z1/Z2/Z3) | Training load | Training characteristics | Outcomes useda | Main findings | ||
|---|---|---|---|---|---|---|---|---|---|
| Sex | Age, y | VO2max baseline | |||||||
| Stöggl et al. (2014) [8] RCT (9 weeks) |
POL: 12 ♂ HIIT: 10 ♂ HVT: 11 ♂ THR: 8 ♂ |
31 ± 6 | 62.6 ± 7.1 (range: 52–75) | Highly Trained/ National Level Endurance athletes (cross-country skiing, cycling, triathlon, middle or long-distance running) |
POL: 68 ± 12/ 6 ± 8/26 ± 7 HIIT: 43 ± 1/ 0/ 57 ± 1, THR: 46 ± 7.54/7/0 HVT: 83 ± 6 / 16 ± 6/1 ± 1 |
NR |
Total training time (h): POL: 104 ± 20 HIIT: 66 ± 1 THR: 84 ± 7 HVT: 102 ± 11 Total number of sessions (n): POL: 54 ± 3 HIIT: 47 ± 1 THR: 49 ± 3 HVT: 58 ± 3 |
VO2peak (mL·min−1·kg−1) TTE (s) V/P LT2 (km·h−1 or W) [Blood lactate] |
VO2peak: ↑ TTE: ↑ V/P LT2: ↑ |
| Muñoz et al. (2014) [17] RCT (10 weeks) |
POL: 16 ♂ THR: 16 ♂ |
POL: 34 ± 9 THR: 34 ± 7 |
POL: 61.0 ± 8.4 THR: 64.1 ± 7.3 |
Trained/ Developmental endurance runners |
POL: 75/5/20 THR: 46/35/19 |
TRIMP/week: POL: 330 ± 67 THR: 370 ± 98 Total TRIMP: POL: 3299 ± 670 THR: 3691 ± 982 |
Total running time (h): POL: 39.1 ± 7.9 THR: 36.3 ± 8.1 Weekly running distance averaged (km): 50 Weekly training frequency (n): 5–6 |
10 km TT (min) | TT: ← → |
| Carnes et al. (2018) [24] RCT (12 weeks) |
POL: 9, 8 ♂ CFE: 12, 7 ♂ |
POL: 44.2 ± 14.6 CFE: 41 ± 12.9 |
POL: 45.9 ± 7.1 CFE: 46.5 ± 6.9 |
Trained/ Developmental Distance runners |
POL: 85/5/10 CFE: 48/8/44 |
TRIMP/week: POL: 389 ± 101 CFE: 222 ± 68 Total TRIMP: POL: 4610 ± 620 CFE: 2641 ± 270 |
Weekly average training time (min): POL: 283 ± 75.9 CFE: 117 ± 32.2 Weekly average distance (km): POL: 47.3 ± 11.6 CFE: 19.3 ± 7.17 |
VO2max (mL·min−1·kg−1) 5km run TT (min) |
VO2max: ↑ 5km run TT: ← → |
| Hebisz et al. (2021) [25] RCT (8 weeks) |
POL: 10, 7♂ BT: 10, 7 ♂ |
POL: 18.5.0 ± 1.9 BT: 18.4 ± 1.6 |
POL: 57.2 ± 5.8 BT: 60.0 ± 4.8 |
Highly Trained/ National Level Mountain bike cyclists | NR | NR |
Total training sessions (n): POL: 12 × SIT, 12 × HIIT, 16 × LIT BT: 11 × SIT, 11 × HIIT, 18 × LIT |
VO2max (mL·min−1·kg−1) P VT2 [W] PETCO2, VE/VCO2 |
VO2max: ↑ P VT2: ← → |
| Neal et al. (2013) [26] RCT (6 weeks) |
POL: 11♂ THR: 11 ♂ |
37.6 | NR |
Trained/ Developmental Cyclists |
POL: 80/0/20 THR: 57/43/0 |
TRIMP/week: POL: 517 ± 90 THR: 633 ± 119 |
Weekly training time (min): POL: 381 ± 85 THR: 458 ± 120 |
40 km cycling TT(s) TTE 95% PPO (s) P LT2 (W) [Blood lactate] |
TT: ← → TTE: ↑ P LT2: ↑ |
| Schumann et al. (2017) [27] N-RCT (12 weeks) |
POL: 14 ♂ TL: 10 ♂ |
POL: 34 ± 7 TL: 34 ± 7 |
POL: 46.4 ± 5.9 TL: 47.3 ± 3.5 |
Trained/ Developmental Endurance runners |
NR |
TRIMP/week: Week 0–4: POL: 301 ± 35 TL: 285 ± 28 Week 5–8: POL: 315 ± 41 TL: 306 ± 42 Week 9–12: POL: 358 ± 52 TL: 269 ± 85 |
Weekly training time (h): POL: 10.8 ± 2.4 CON: 10.0 ± 2.7 |
VO2max (mL·min−1·kg−1) 1000m TT (min) TTE (min) |
VO2max: ↑ TT: ← → TTE: ← → |
| Festa et al. (2020) [28] RCT (8 weeks) |
POL: 19, 15 ♂ THR: 19, 16 ♂ |
POL: 43.2 ± 8.4 THR: 39.4 ± 8.5 | POL 53.0 ± 5.9 THR: 53.7 ± 1.9 |
Trained/ Developmental runners |
POL: 77/3/20 THR: 40/50/10 |
TRIMP/week: POL: 308 ± 47.46 THR: 319.8 ± 28.1 Total TRIMP: POL: 2464 ± 124 THR: 2558.2 ± 10.9 |
Total running time (h): POL: 29.9 ± 3.1 THR: 24.8 ± 2.0 |
VO2max (mL·min−1·kg−1) 2km TT (s) vRCT (km h−1) VE/VCO2 |
VO2max: ← → TT: ← → V RCT: ← → |
| Röhrken et al. (2020) [29] RCT (6 weeks) |
POL: 7, 5 ♂ THR: 8, 6 ♂ |
POL: 29.1 ± 7.6 THR: 30.3 ± 6.1 | NR |
Trained/ Developmental Triathletes |
POL: 75.2 ± 14.4/11.1 ± 10.9/13.7 ± 4.1 THR: 77.8 11.9/20.3 ± 10.8/2.0 ± 1.5 |
TRIMP/week: POL:882.0 ± 155 THR:739.0 ± 162 |
Weekly training time (h): POL: 10.8 ± 2.4 THR: 10.0 ± 2.7 |
V LT2 (km·h−1) [Blood lactate] P LT2 (W) [Blood lactate] |
V LT2: ← → P LT2: ← → |
| Treff et al. (2017) [30] N-RCT (11 weeks) |
POL: 7 ♂ PYR: 7 ♂ |
POL: 21 ± 2 PYR: 19 ± 1 |
POL: 68 ± 7 PYR: 64 ± 3 |
Highly Trained/ National Level Rowers |
POL: 93/2,1 ± 1/6 ± 3 PYR: 94 ± 3/3 ± 2/2 ± 1 |
NR |
Total rowing distance (km): POL: 1334 ± 67 PYR: 1255 ± 264 Total rowing time (min): POL: 5953 ± 315 PYR: 5919 ± 1216 Total number of sessions (n): POL: 80 ± 4 PYR: 84 ± 13 |
VO2max (mL·min−1·kg−1) 2000m TT (s) P LT2 (W) [Blood lactate] |
VO2max: ← → TT: ← → P LT2 ↓ |
| Selles-Perez et al. (2019) [32] N-RCT (13 weeks) |
POL: 6 ♂ PYR: 7 ♂ |
POL: 28.5 ± 7.7 PYR 29.2 ± 6.8 |
Run POL: 52.8 ± 4.1 Run PYR: 58.1 ± 3.9 Bike POL: 50.5 ± 2.9 Bike PYR: 54.1 ± 5.1 |
Trained/ Developmental Triathletes |
POL: 84.5/4.2/11.3 PYR: 77.9/18.8/ 3.3 |
ECOs/week: POL: 785.2 ± 244.9 PYR: 751.6 ± 234.9 |
Total training time (h): 155 Weekly average training time (h): POL: 11.9 ± 3.5 PYR: 11.9 ± 3.6 Total training sessions (n): PYR: 106 (28 for swimming, 34 for cycling and 44 for running) POL: (28 for swimming, 34 for cycling and 45 for running) |
VO2max running (mL·min−1·kg−1) VO2max cycling (mL·min−1·kg−1) V/P VT2 (Running, Cycling and Swimming) PETCO2, VE/VCO2 |
VO2max running: ↑ VO2max cycling: ← → VT2 Running: ↑ VT2 Cycling: ← → VT2 Swimming: ↓ |
| Stöggl et al. (2017) [52] RCT (9 weeks) | 31 | 31 ± 6 | 61.9 ± 8.0 (range 54–75) | Highly Trained/ National Level Endurance athletes (cross-country skiing, cycling, triathlon, middle- or long-distance running) |
POL: 68 ± 12/ 6 ± 7/26 ± 7 HIIT: 43 ± 1/0/ 57 ± 1 HVLIT: 64 ± 20/35 ± 21/ 1 ± 1 |
NR |
Total training time (h): POL: 104 ± 21 HIIT: 66 ± 1 HVLIT: 93 ± 13 Total number of sessions (n): POL: 54 ± 7 HIIT: 47 ± 1 HVLT: 54 ± 8 |
V/P VT2/LT2 (km·h−1 or W) [Blood lactate] |
V/P at VT2/LT2: ← → |
| Zapata-Lamana et al. (2018) [53] RCT (12 weeks) |
POL: 14 ♀ MICT: 14 ♀ HIIT: 14 ♀ CG: 10 ♀ |
POL: 21.8 ± 1.9 MICT: 21.3 ± 1.4 HIIT: 21.2 ± 1.4 CG: 22.7 ± 3.2 |
POL: 24.5 ± 2.5 MICT: 22.7 ± 3.1 HIIT: 25.3 ± 2.6 CG: 25.0 ± 4.0 |
Sedentary |
POL: 70–80/0/ 20–30 NR |
NR |
Total number of cycling sessions (n): 36 Weekly number of cycling sessions (n): 3 Weekly cycling time (min): POL: 120 MICT: 135–150 HIIT: 156 |
VO2peak (mL·min−1·kg−1) | VO2peak: ↑ |
| Pla et al. (2019) [54] RCT (6 weeks) |
POL: 9 THR: 13 12 ♂, 10 ♀ |
POL: 17 ± 3 THR: 17 ± 3 |
POL: 56.0 ± 11.3 THR: 56.4 ± 12.4 |
Highly Trained/ National Level junior swimmers |
POL: 81/4/15 THR: 25/65/10 |
NR |
Weekly training distance (km) POL: 42 ± 4 THR: 42 ± 4 |
100m TT (s) V LT2 (m/s) [Blood lactate] |
TT: ↑ V LT2 ↓ |
| Schneeweiss et al. (2022) [55] RCT (4 weeks) |
POL: 10, 8 ♂ LIT: 8, 6 ♂ |
POL: 18.4 ± 4.7 LIT: 17.4 ± 1.9 | NR | Highly Trained/ National Level XCO athletes |
POL: 86.6/0/13.4 LIT: 100/0/0 |
NR |
Total training time (h): POL: 25 LIT: 40 |
TT (300s) P LT2 (W) [Blood lactate] |
TT: ← → P LT2: ← → |
| Filipas et al. (2022) [56] RCT (16 weeks) |
POL: 14 ♂ PYR: 14 ♂ |
POL: 38 ± 5 PYR: 35 ± 6 |
POL: 69 ± 3 PYR: 68 ± 4 |
Trained/ Developmental runners |
POL: 78–81/4–7/14–15 PYR: 77–78/ 15–17/6–7 |
TRIMP/week: Week 1–8: PYR: 463 ± 77 POL: 464 ± 81 Week 9–18: PYR: 462 ± 78 POL: 465 ± 79 |
Weekly training time (min): Week 1–8: PYR: 358 ± 63 POL: 348 ± 57 Week 9–18: PYR: 358 ± 63 POL: 348 ± 56 |
VO2max (mL·min−1·kg−1) 5-km TT (s) V LT2 (km·h−1) [Blood lactate] |
VO2max: ← → TT: ← → V LT2: ← → |
| Pérez et al. (2019) [57] RCT (12 weeks) |
POL: 11 ♂ THR: 9 ♂ |
POL: 40.6 ± 9.7 THR: 36.8 ± 9.2 |
POL: 55.8 ± 4.9 THR 57.1 ± 5.2 |
Trained/ Developmental Ultra-endurance runners |
POL: 79.8 ± 2.1/ 3.9 ± 1.9/ 16.4 ± 1.5 THR: 67.2 ± 4.6/33.8 ± 4.6/0 |
Total TRIMP: POL: 5906.0 ± 708.8 THR: 6061.2 ± 1726.2 |
Weekly training time (h): POL: 6.0 ± 0.8 THR: 6.5 ± 1.4 Weekly training frequency (n): 5 |
VO2max (mL·min−1·kg−1) TTE (s) V VT2 (km h−1) PETCO2, VE/VCO2 |
VO2max: ← → TTE: ↑ V VT2: ← → |
| Hebisz et al. (2021) [58] RCT (9 weeks) |
POL: 14 ♂ CG: 12 ♂ |
POL: 21.7 ± 7.7 CON: 20.5 ± 5.5 |
POL: 62.3 ± 6.4 CON: 59.6 ± 8.4 |
Highly Trained/ National Level Mountain bike cyclists | NR | NR |
Total training sessions (n): POL: 2 × SIT, 1 × HIIT, and 2 × ET CG: 2 × HIIT, 3 × ET |
VO2max (mL·min−1·kg−1) | VO2max: ↑ |
BT block training, CFE© CrossFit endurance training ©, CG Control Group, ECOs Objective Load Equivalents, ET endurance training, h hours, HIIT high-intensity interval training, HVLIT high-volume low-intensity training, km.h−1 km per hour, LIT low-intensity training, m.s−1 m per second, MICT moderate intensity continuous training, n number of sessions, N-RCT Non Randomized Controlled Trial, NR Not reported, P LT2—power at second lactate threshold, P VT2power at second ventilatory threshold, PETCO2 end-tidal carbon dioxide pressure, POL polarized training, PPO peak power output, PYR pyramidal training, RCT Randomized Controlled Trial, RCT respiratory compensation threshold, s seconds, SIT sprint interval training, THR threshold training, TID training intensity distribution, TL training load guided, TRIMP training impulse, TT time trial, TTE time-to-exhaustion, V LT2velocity at 2nd lactate threshold, V RCT Velocity at respiratory compensation threshold, V VT2velocity at 2nd ventilatory threshold, VE/VCO2 minute ventilation/carbon dioxide production, V/P at VT2/LT2 velocity or power at second ventilatory or lactate threshold, VO2max maximal oxygen uptake, VO2peak peak oxygen uptake, W Watts, Z1 training zone 1, Z2 training zone 2, Z3 training zone 3
aThe main outcomes gathered from each of the studies included in the review are listed together with the method used to determine V/P at VT2/LT2
Note: Age is expressed as mean ± SD
Symbols: Female (♀), male (♂), decreased (↓), increased (↑) and equal (← →) regarding POL compared to other TIDs