Salvador Vargas-Molina, Manuel García-Sillero, Diego A Bonilla, Jorge L Petro, Jerónimo García-Romero, Javier Benítez-Porres
Journal: Journal of the International Society of Sports Nutrition 2024;21(1):2306308
PMID: 38285913
The ketogenic diet (KD) is characterised by a reduction in daily carbohydrate intake to less than 50 grams, which represents less than 10% of total calories, coupled with an increased intake of fats and possibly proteins. The aim of this study was to evaluate the effect of a 6-week KD on load management variables in resistance-trained participants. This study was a single-arm, repeated-measures clinical trial involving 14 resistance-trained individuals (3 females, 11 males). Results showed that the RPE (number of repetitions, perceived exertion) was higher in the initial weeks but gradually decreased as the programme progressed. The effort index exhibited a significant increase between the pre-ketosis week and the subsequent weeks, with a significant difference compared to the first week of ketosis. Additionally, both the volume load and the number of repetitions significantly decreased during the first week and gradually increased from the second week onwards. Authors concluded that a KD does not lead to performance losses in recreational strength participants during a resistance training programme. However, adherence and familiarity with the diet are crucial, especially in the initial weeks.
BACKGROUND
The effect of low-carbohydrate high-fat dietary manipulation, such as the ketogenic diet (KD), on muscle strength assessment in resistance-training (RT) participants has focused on the one-repetition maximum test (1-RM). However, a pre-specified 1-RM value during an exercise training program disregards several confounding factors (i.e. sleep, diet, and training-induced fatigue) that affect the exerciser's "true" load and daily preparedness. We aimed to evaluate the effect of a 6-week RT program on load control-related variables in trained subjects following a KD intervention.
METHODS
Fourteen resistance-trained individuals (3F, 11 M; 30.1 [6.2] years; 174.2 [7.6] cm; 75.7 [10.8] kg; BMI 24.8 [2.1] kg·m) completed this single-arm repeated-measures clinical trial. Load management variables included volume load, number of repetitions, perceived exertion (RPE), movement velocity loss, and exertion index. These primary outcomes were assessed weekly before, during, and at the end of a 6-week RT program that included traditional RT exercises (bench press, femoral lying down, lat pulldown, leg extension, and back squat).
RESULTS
There was a significant difference in RPE between weeks ( = 0.015, W = 0.19) with a slight trend in decreasing RPE. We found differences in the volume load per week ( < 0.001; W = 0.73 and < 0.001, W = 0.81, respectively), with an increase in the last weeks. In the control of the load based on movement velocity, we did not find significant differences between weeks ( = 0.591, W = 0.06), although significant differences were found in the effort index ( = 0.026, W = 0.17).
CONCLUSIONS
A KD diet in recreational strength participants does not appear to lead to performance losses during a RT program aimed at improving body composition. However, the lack of adherence and familiarity with the ketogenic diet must be considered specially during first weeks.
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