Adherence to a Ketogenic Low-Carbohydrate, High-Fat Diet Is Associated With Diminished Training Quality in Elite Racewalkers

Abstract

Purpose: To examine the effects of a high-carbohydrate diet (HCHO), periodized-carbohydrate (CHO) diet (PCHO), and ketogenic low-CHO high-fat diet (LCHF) on training capacity. Methods: Elite male racewalkers completed 3 weeks of periodic training while adhering to their dietary intervention. Twenty-nine data sets were collected from 21 athletes. Each week, 6 mandatory training sessions were completed, with additional sessions performed at the athlete’s discretion. Mandatory sessions included an interval session (10 × 1-km efforts on a 6-min cycle), tempo session (14 km with a 450-m elevation gain), 2 long walks (25–40 km), and 2 easy walks (8–12 km) where “sleep-low” and “train-low” dietary strategies were employed for PCHO. Racewalking speed, heart rate, rating of perceived exhaustion, and blood metabolites were collected around key sessions. Results: LCHF covered less total distance than HCHO and PCHO (P < .001); however, no differences in training load between groups were evident (P = .285). During the interval sessions, walking speed was slower in LCHF (P = .001), equating to a 2.8% and 5.6% faster speed in HCHO and PCHO, respectively. LCHF was also 3.2% slower in completing the tempo session than HCHO and PCHO (P = .001). Heart rate was higher (P = .002) and lactate concentrations were lower (P < .001) in LCHF compared to other groups, despite slower walking speeds during the interval session. No between-groups differences in rating of perceived exhaustion were evident (P = .077). Conclusion: Athletes adhering to an LCHF diet showed impaired training capacity relative to their high-CHO-supported counterparts, completing lower training volumes at slower speeds, with higher heart rates.

The Impact of a Short-Term Ketogenic Low-Carbohydrate High-Fat Diet on Biomarkers of Intestinal Epithelial Integrity and Gastrointestinal Symptoms

“…The LCHF group walked significantly slower during the Adaptation trial yet had a higher average HR and RPE. This response has been reported previously during the adaptation to a LCHF diet (McKay et al, 2023) and likely represents the shift toward fat as the primary fuel source (Burke et al, 2021). An increase in HR may reflect increased blood flow to the skin, rather than gastrointestinal tract, increasing EIGS.…”

The Physiological Requirements of and Nutritional Recommendations for Equestrian Riders

“…With the possible exception of endurance riding [29], there does not appear to be a physiologically relevant advantage to consuming a high-fat diet for equestrian athletes. Evidence suggests likely ergolytic or performance-impairing effects [152,153] due to high-fat diets only matching performance at low-moderate endurance intensities and potentially impairing performance at higher intensities relative to sufficient CHO provision [154,155]. This is attributed to decreased enzymatic activity, lowered glycogenolysis, and an increased oxygen cost of exercise for the same output [154,[156][157][158].…”

Effects of a 10-Week Exercise and Nutritional Intervention with Variable Dietary Carbohydrates and Glycaemic Indices on Substrate Metabolism, Glycogen Storage, and Endurance Performance in Men: A Randomized Controlled Trial

“…As a result, performance at higher intensities is possibly limited after longer periods on high-fat diets on the one hand because of reduced glycogen stores [ 22 ] and on the other hand because of the mitigated carbohydrate metabolism [ 23 ]. In addition to this, other side effects such as decreased training capacity [ 24 ] or exercise economy [ 25 ] and reduced well-being, fatigue, gastrointestinal complaints, or poor concentration due to lack of micronutrients and glycogen can occur during or after the change to a LCHF diet [ 26 ].…”