TABLE 3.
Study design, duration, and endurance-type performance measurement outcome in healthy subjects in systematic reviews split by training status1
| First author (ref) | Study design | Duration, d | Performance measure | Performance outcome2 |
|---|---|---|---|---|
 O2max ≥53 mL · kg−1 · min−1
|
||||
| Burke et al. (16) | Parallel NRCT | 21 | TT, race walk (10 km) | ↔ |
| Burke et al. (37) | Parallel NRCT | 25 | TT, race walk (10 km) | ↓ |
| McSwiney et al. (18) | Parallel NRCT | 84 | TT, cycle ergometer (100 km) | ↔ |
| Phinney et al. (12) | Longitudinal | 28 | TTE, cycle ergometer (60–65%  O2max) |
↔ |
| Prins et al. (28) | Crossover RCT | 42 | TT, treadmill (5 km) | ↔ |
| TTE, cycle ergometer (graded intensity) | ↔ | |||
| Shaw et al. (29) | Crossover RCT | 31 | TTE, treadmill (70%  O2max) |
↔ |
 O2max <53 mL · kg−1 · min−1
|
||||
| Cipryan et al. (15) | Parallel BRCT | 28 | TTE, treadmill (100%  O2max) |
↔ |
| Dostal et al. (33) | Parallel NRCT | 84 | TTE, treadmill (graded test) | ↔ |
| TTE, shuttle run (30–15 intermittent fitness test) | ↔ | |||
| Heatherly et al. (27) | Longitudinal | 21 | TT, treadmill (5 km) | ↔ |
| Sjodin et al. (30) | Crossover RCT | 28 | TTE, cycle ergometer (graded intensity) | ↓ |
| Zinn et al. (31) | Longitudinal | 70 | TTE, cycle ergometer (graded intensity) | ↓ |
1BRCT, block randomized controlled trial; CON, mixed macronutrient control diet; KD, ketogenic diet; NRCT, nonrandomized controlled trial; RCT, randomized controlled trial; ref, reference; TT, time trial; TTE, time-to-exhaustion; 
O2max, maximal oxygen uptake.
2
Physical performance significantly lower (↓), higher (↑), or not different (↔) following a KD compared with CON.