Efeitos do treinamento resistido para falha muscular sobre a fadiga aguda: uma revisão sistemática e meta-análise

Abstract

Proper design of resistance trainingvariables is a key factor to reach the maximum potential of neuromuscular adaptations. Among those variables, the use of resistance trainingperformed to failure (RTF) may lead to different magnitude of acute fatigue compared to resistance trainingnot performed to failure (RTNF). The fatigue response could interfere with acute adaptive changes, in turn regulating long-term adaptations. Considering that level of fatigue affects long-term adaptations, it is important to determine how fatigue is affected by RTF vs. RTNF. The aim of this systematic review and meta-analysis was to compare RTFversus RTNFon acute fatiguein adults men. The search was conducted in January 2021 in seven databases. Only studies with cross-over design that investigated the acute biomechanical properties (vertical jump height, velocity of movement, power output, and isometric strength), metabolic response (lactate and ammonia concentration), muscle damage (creatine kinase activity), and RPE were selected. The data (mean ± standard deviation) were extracted from included studies and converted into standardized mean difference (SMD) or maintained in the raw mean difference (RMD) when the studies reported the results in the same unit of measure. Fixed or random effects meta analyses were performed. Twenty studies were included in the systematic review. The main meta-analyses indicated greater decrease of biomechanical properties for RTF compared to RTNF (SMD = -0.96 [95% CI -1.43; -0.49]; p< 0.001). Furthermore, there was a larger increase in metabolic response (RMD = 5.54 mmol·L-1[95% CI 4.16; 6.92]; p< 0.001), muscle damage (SMD = 0.75 [95% CI 0.35; 1.14]; p< 0.001) and rating of perceived exertion (RPE; SMD = 2.47 [95% CI 1.25; 3.68]; p< 0.001) for RTF compared to RTNF. Further exploratory subgroup analyses showed that training status (p= 0.92), time point (p= 0.89), and load (p= 0.08) did not affect biomechanical properties. However, greater loss in the movement velocity test occurred on upper-limbs compared to lower-limbs (p< 0.001). Blood ammonia concentration was greater in RTF than RTNF (RMD = 42.17 μmol·L-1[95% CI 34.67; 49.67]; p< 0.001) and only 48h post-exercise blood creatine kinase activity was higher after RTF than RTNF (SMD = 0.86 [95% CI 0.40; 1.31]; p< 0.001). Therefore, it can be concluded that RTF leads to greater acute fatigue compared to RTNF. The higher acute fatigue after RTF can also have an important impact on chronic adaptive processes following resistance training. However, the greater acute fatigue following RTF can extend the time needed for recovery what 11should be considered when RTF is used. The original protocol of systematic review was prospectively registered (CRD42020192336) in the International Prospective Register of Systematic Review (PROSPERO).