From: A review of the ketogenic diet for endurance athletes: performance enhancer or placebo effect?
Reference | VO2 max outcomes (mL/kg/min) | Time to exhaustion (TTE) | Race time/Time trial | Rating of perceived exertion (RPE) | Peak power |
---|---|---|---|---|---|
Prospective Trials | |||||
Burke et al. 2017 [12] | Significant increase in VO2max from baseline (p < 0.001) in all three groups. VO2 Max of the HCD group was significantly lower than for the other groups both pre- and post-diet (p ≤ 0.02). Pre- vs. post-intervention EAKD: 66.3 vs. 71.1 HCD: 61.6 vs. 66.2 PCHO: 64.9 vs. 67.0 | _ _ | EAKD group: Non-significant increase in 10 km race time from baseline. HCD and PCHO groups: Significant decrease in race time (p < 0.01). Pre- vs. post-intervention EAKD: 23 s slower HCD: 190 s faster PCHO: 124 s faster | EAKD group: Significantly higher RPE values for post-intervention graded economy test compared with pre-intervention RPE values (p ≤ 0.01). Non-significant trend for higher RPE values during 25 km long walk for both pre- and post-testing. | _ _ |
Carr et al. 2018 [7] | Significant increase in VO2max from baseline (p < 0.05) in all three groups. Between groups analysis not reported. Pre- v. post-intervention (M ± SD) EAKD: 61.1 ± 5.3 vs. 63.4 ± 4.1 HCD: 57.6 ± 4.6 vs. 58.3 ± 4.1 PCHO: 58.1 ± 3.3 vs. 60.2 ± 3.8 | _ _ | _ _ | _ _ | _ _ |
Heatherly et al. 2018 [13] | Post-EAKD VO2 max not measured. Study reported % baseline VO2 max at various race paces. At 10 km, 21 km, 42 km and sub-42 km (but not 5 km) race paces, % relative VO2max was significantly greater post-EAKD. Example (10 km pace; p < 0.05): EAKD: 98.7 ± 11.3 HCD: 92.8 ± 5.3 | _ _ | 5 km time trial time was not significantly different pre- vs. post-EAKD (p > 0.10). Pre- vs. post-intervention EAKD: 23.45 ± 2.25 min. HCD: 23.92 ± 2.57 min. | Overall RPE did not differ significantly pre- vs. post-EAKD during 5 km time trial (P > 0.10). Pre- vs. post-intervention EAKD: 8.4 ± 1.2 HCD: 8.0 ± 1.0 | _ _ |
McSwiney et al. 2018 [14] | Increase in both groups post-diet. Non-significant difference between groups (p = 0.968). Pre- vs. post-intervention EAKD: 53.6 ± 6.8 vs. 57.3 ± 6.7 HCD: 52.6 ± 6.4 vs. 57.2 ± 6.1 | _ _ | 100 km time trial time was not significantly different between groups (p = 0.057). Pre- vs. post-intervention EAKD: 4.07 min.sec faster HCD: 1.13 min.sec faster | _ _ | Post-intervention peak power was significantly different between groups (p = 0.047). Pre- vs. post-intervention EAKD: 8.3 ± 2.2 vs. 9.7 ± 2.3; 1.4 watts/kg increase HCD: 9.1 ± 2.6 vs. 8.4 ± 2.2; 0.7 watts/kg decrease |
Phinney et al. 1983 [15] | Non-significant decrease from baseline (HCD; p > 0.01). Pre- vs. post-intervention EAKD: 5.00 ± 0.20 HCD: 5.10 ± 0.18 | Non-significant increase in mean exercise times from baseline (HCD). Pre- vs. post-intervention EAKD: 151 ± 25 min. HCD: 147 ± 13 min. | _ _ | _ _ | _ _ |
Shaw et al. 2019 [16] | No significant change from pre-intervention levels for either dietary exposure (p > 0.05). Pre-intervention (all athletes) 59.4 ± 5.2 | No significant difference between dietary interventions (p = 0.56). Pre- vs. post-intervention EAKD: 239 ± 27 vs. 219 ± 53 min. (p = 0.36) HCD: 237 ± 44 vs. 231 ± 35 min. (p = 0.44) | _ _ | RPE values were similar for each dietary intervention during run-to-exhaustion trials. 1-h, 2-h, at exhaustion EAKD: 11.4 ± 0.9, 12.1 ± 1.4, 19.38 ± 0.52 HCD: 11.7 ± 0.8, 12.8 ± 0.9, 19.38 ± 0.52 | _ _ |
Case studies | |||||
Zinn et al. 2017 [17] | Non-significant change from baseline (M ± SD): − 1.69 ± 3.4 (p = 0.63). (with a decrease in four of the five athletes) | Significant decrease in TTE for all participants (p = 0.004). Mean change from baseline EAKD: − 2 ± 0.7 min. | _ _ | _ _ | Four out of five athletes experienced a decrease in peak power from baseline (p = 0.07). Mean change from baseline EAKD: − 18 ± 16.4 watts |