<strong>The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants</strong>
Creators: name: VARGAS MOLINA, SALVADOR
name: Bonilla, Diego A.
name: Benítez-Porres, Javier
Publisher: name: figshare
Year: 2023
Subjects: Sports science and exercise not elsewhere classified
Exercise physiology
Motor control

description: <strong>Trial design</strong> This was a single-arm non-randomized own-control clinical trial to evaluate the effects of a 6-week KD intervention on RT performance in resistance-trained individuals. Strength-related variables were assessed before, during and after the dietary intervention. <br> <strong>Participants</strong> We invited physically active individuals who had engaged in continuous weight RT for at least one year to participate in the study. Participants were recruited from fitness centers located in Malaga, Spain. We excluded participants who had used performance and image enhancing drugs, such as anabolic androgenic steroids, within the previous two years. Additionally, individuals who consumed any type of nutritional supplement during the program were also excluded from the study. The participants were informed of the possible risks of the experiment and signed an informed consent form. All participants agreed to follow the prescribed diet and scheduled sessions during the intervention period and to refrain from any other physical activity on the day and the day before the sessions. The study was developed in accordance with the ethical guidelines of the Declaration of Helsinki of the World Medical Association and approved by the ethics committee of the University of Malaga (code: 38-2019-H). <strong>Interventions</strong> <em>Familiarization</em> A familiarization session was carried out, where the loads were adjusted, a 1-RM was performed, and the exercise technique was supervised. The technique of the exercises used was evaluated, and the 1-RM was measured in the exercises Squat, Lat pull down, Femoral lying, Leg extension, Bench press (Gervasport, Madrid, Spain) based on our laboratory procedures (Romance et al., 2019). Additionally, we proceeded to adjust the loads to 10 repetitions with RIR (1-2) and perform a familiarization in Squat using the linear position transducer. Additionally, the nutritional protocol was explained by the sports nutrition specialist, and anthropometric measurements were carried out. <em>Exercise protocol</em> From the first week after the start of ketosis to the sixth week, a previous warm-up was carried out. Subsequently, one set of Bench press was performed with the load calculated in the familiarization session, 10 repetitions (RIR, 1-2). In the second set, the load was adjusted according to the participant's needs, the kilos were increased, reduced or maintained depending on their perceptions, with the intention of maintaining the same number of repetitions and intensity. Finally, the third set was performed counting the maximum number of repetitions with 70% of the 1-RM, and this weight was maintained during all sessions. Participants rested two minutes between sets and a controlled movement velocity of approximately one second in the concentric phase and one in the eccentric phase was maintained. Likewise, the same protocol was carried out in the exercises Leg extension, Lat pull down and Lying Femoral, in that order in all sessions. Finally, we proceeded to perform three sets of 12 repetitions in Squat using a linear encoder with 70% of the 1-RM based on (M. Garcia-Sillero et al., 2022), to assess velocity loss and perceived effort. At the end of the sessions, all the participants reported their perception of the training session on a scale of 1 to 10. <em>Nutrition Intervention</em> The participants were instructed to consume 30-40 g·d-1 carbohydrates with a protein intake of 2 g·kg-1·d-1 protein (Vargas-Molina et al., 2021), and the rest in the form of fats <em>at libitum</em>. Participants were advised to eat 3 - 6 meals a day. To assess dietary compliance, urinary ketones concentrations were measured weekly in the early morning using over-the-counter reagent strips (<em>Ketostix, Bayer Vital GmbH, Leverkusen, Germany</em>) (Urbain &amp; Bertz, 2016; Vargas et al., 2018). <br> <strong>Outcomes</strong> The performance was evaluated through a training session, before ketosis, one week after ketosis, and in the second, third, fourth, fifth and sixth week of the KD protocol. A full-body session was assessed, including Squat, Bench Press, Leg Extension, Lat Pull down and lying femoral exercises. The sessions were carried out in the following order: Bench Press, Leg Extension, Lat pull down and lying femoral. Each exercises consisted of two sets of 10 repetitions, with two repetitions left in the chamber (RIR, 1-2), followed by a third set with the maximum number of repetitions. After completing these four exercises, three sets of 12 Squat repetitions were performed at maximum movement velocity, which was controlled by a linear position transducer. In between sets and exercises, there was a 2-minutes break. Figure 1 shows the intervention protocol. <em>Anthropometry</em> All anthropometric data was collected during the first visit to the laboratory during the familiarization period. Body mass was measured with a digital scale to the nearest 50 grams (Tanita RD-545, Tokyo, Japan). A fixed stadiometer was used to measure the stature (SECA 220, Hamburg, Germany). <em>Volume load</em> The training volume was evaluated in terms of sets x repetitions x load. The sets were kept constant during all sessions, while the load moved was adjusted based on the participant's perception during each set and exercise. It has been shown that volume is the variable with the greatest influence on structural adaptations to resistance training (Vann et al., 2022). <em>Repetitions to failure</em> The total number of sets was evaluated in each training session during all the weeks that the research lasted (pre- and post-KD protocol ketosis). For this purpose, the three sets of 12 repetitions used in the squat were added. Also, the first two sets of each exercise performed at 10 repetitions (Leg extension, Bench press, Lat pull down, and Lying leg curl) were added. All this added up to a total of 116 repetitions, where the last set of each exercise (except Squat) was performed to the maximum number of repetitions, reaching voluntary failure, where it has been shown that a higher number of repetitions generates a higher load volume (Iglesias-Soler, Carballeira, Sanchez-Otero, Mayo, &amp; Fernandez-del-Olmo, 2014) , which may be more optimal for hypertrophy (Vann et al., 2022). <em>Rating of perceived exertion</em> At the end of each session, data on subjective perception of effort were collected using the visual analogue scale of 1 to 10 of the rating of perceived exertion (RPE) (Foster et al., 2001). <em>Velocity loss</em> The velocity loss in the Squat was evaluated during three sets performed at the end of each session, as a lower velocity loss is related to better mechanical performance (García-Ramos et al., 2020; González-Hernández et al., 2020). A linear position transducer (SmartCoach Power Encoder SPE-35, SmartCoach Europe AB, Stockholm, Sweden) was used for this purpose. <em>Exertion index</em>The Exertion Index of the three Squat sets was evaluated using data obtained from the linear position transducer. The average velocity of the first repetition and the percentage of velocity loss were used to calculate this index. This data was obtained from the three sets performed in the exercise as we have conducted previously (Manuel Garcia-Sillero et al., 2022). <strong>Sample size</strong> Non-probability sampling (convenience sampling) was used as it is often a strategy used in pilot and feasibility studies (Bonilla et al., 2021). After the call to participate in this study, 22 subjects were suitable for eligibility from the available population (i.e., resistance-trained men attending the fitness and strength conditioning center ‘Physical Training’ located in Malaga, Spain).