Influência do jejum no desempenho de força

Abstract

INTRODUCTION: 16/8 intermittent fasting (IF) has been studied as an alternative to conventional nutritional strategies, with the aim of promoting positive adaptations in body composition. It is necessary to verify the impact of this nutritional strategy on strength performance, especially when resistance training is performed at the time of fasting. OBJECTIVES: to verify the acute influence of fasting on the strength performance of resistance trained men and to compare the influence of different fasting durations on performance. METHODS: 16 male subjects (24.9 ± 3.12 years), recreationally trained in resistance training, were recruited. Performance was assessed by isometric maximal strength test in the smith squat (AGS), countermovement jump (SCM) and a resistance training session. The maximum number of repetitions (MNR) and the total load volume (TLV) were used to monitor the performance of the training sessions. The training session consisted of performing the AGS and Leg press (LEG) exercises, with 5 sets of each exercise, with 70% of 1RM and a 2-minute interval between sets. Sessions were performed under one of three conditions: fed (FED); 15h fasting training, concluding 16h fasting after the end of the session (16IF) and 11h fasting training, concluding 12h fasting after the end of the session (12IF). The Appetite Perception Questionnaire (APQ) was applied before, after and during the sessions. RPE was collected 60 seconds after each set of the training session while session RPE was collected 30 minutes after the end of the session. Blood glucose was measured upon arrival at the collection site, during and at the end of the session, while blood lactate was measured at the beginning and end of the session. RESULTS: The ONE-WAY ANOVA did not identify significant differences between dietary conditions in the maximum strength of the isometric test (N) (FED: 224.84 ± 38.09; IF12: 224.28 ± 45.86; IF16: 228, 65 ± 48.14), at the maximum height of the CMJ (cm) (FED: 35.2 ± 0.04; IF12: 35.2 ± 0.04; IF16: 35.4 ± 0.04) and at the peak of CMJ power (cm) (FED: 1880 ± 263.13; IF12: 1945.03 ± 291.90; IF16: 1914.63 ± 369.69). No significant differences were identified in the NMR of the Smith Machine (SM) (FED: 10.63 ± 3.44; IF12: 10.38 ± 4.06; IF16: 9.88 ± 4.06), of the Leg Press 45º (LEG) (FED: 10.19 ± 3.82; IF12: 10.25 ± 3.38; IF16: 10.19 ± 3.17) or in the TLV (FED: 18852.24 ± 4541.88; IF12: 18749.35 ± 4897.08; IF16: 18337.33 ± 5124.48). The subjective perception of hunger and the ability to eat were significantly higher in the fasted conditions than in the fed state, while satiety was significantly lower in the fasted conditions than in the fed state. Blood glucose was maintained throughout the session and unchanged between dietary conditions. Blood lactate was significantly higher in the post-session period compared to pre-session, regardless of dietary condition. CONCLUSION: Fasting by time-restricted eating (TRE) of 12 and 16 hours did not interfere in the performance of strength tests and in a resistance training session.