Acute performance, physiological and perceptual responses to repeated-sprint exercise with continuous or intermittent blood flow restriction

J. Mckee; O. Girard; J. Peiffer; B. Scott

doi:10.1016/j.jsams.2023.08.022

Introduction: Team sport athletes commonly perform repeated short-duration sprints (≤ 10 s) interspersed by brief recovery periods (≤ 60 s). Repeated-sprint training augments physiological determinants of repeated-sprint ability which are further improved with systemic hypoxia (i.e., reduced fraction of inspired oxygen). Blood flow restriction (BFR) is an alternative hypoxic strategy utilizing inflatable cuffs on the legs that limit arterial inflow of blood and mostly occlude venous return. Cuffs can be applied continuously (i.e., C-BFR), or intermittently during only work (i.e., I-BFRWORK) or intra-set rest periods (i.e., I-BFRREST). The purpose of this study was to examine the influence of cuff application method during repeated-sprint exercise (RSE) on acute performance, physiological and perceptual responses in Australian Rules football players. Methods: Twelve adult male semi-professional Australian football players completed one familiarization session and four RSE sessions (3 x [5 x 5-second maximal sprints:25-second passive recovery], 3-minute rest between sets) on a mechanically-braked cycle ergometer with C-BFR, I-BFRWORK, I-BFRREST, or no restriction (i.e., Non-BFR). Power output and cardiorespiratory responses were continuously monitored, and mean values were calculated for each set. Fingertip capillary blood samples were assessed for blood lactate concentration after two minutes of rest following each set. Rating of perceived exertion and lower-limb discomfort were collected at the end of each set. Linear mixed models were used to compare differences in means of dependent variables between conditions and sets, and an alpha level of p < 0.05 was used to determine significance. Results: Mean power output was greater for Non-BFR (p < 0.001, dz = 1.58), I-BFRWORK (p = 0.002, dz = 0.63), and I-BFRREST (p = 0.003, dz = 0.69) than C-BFR, and for Non-BFR (p = 0.043, dz = 0.55) compared with I-BFRREST. Blood lactate concentration (p = 0.166) did not differ between conditions. Ratings of perceived exertion were greater for I-BFRREST (p = 0.042, dz = 0.51) and C-BFR (p = 0.011, dz = 0.90) than Non-BFR, and during C-BFR (p = 0.023, dz = 0.54) compared with I-BFRWORK. Similarly, perceived limb discomfort was higher during I-BFRREST (dz = 0.94 and 0.66; respectively) and C-BFR (dz = 1.19 and 0.84; respectively) than Non-BFR and I-BFRWORK Discussion: Similar blood lactate concentration was observed between conditions despite lower mean power output during C-BFR and I-BFRREST than Non-BFR. Therefore, reduced oxygen delivery and phosphocreatine resynthesis with C-BFR and I-BFRREST likely increases peripheral fatigue development and is preferential for athletes who want to obtain a greater metabolic load during RSE for a given mechanical stress. However, C-BFR and I-BFRREST were perceived as more difficult which was driven by greater perceptions of limb discomfort due to increased metabolic stress and discomfort associated with cuff pressure. Therefore, C-BFR and I-BFRREST may not be tolerated as well by athletes which can limit exercise compliance. Impact/Application to the field: Practitioners should be aware that C-BFR or I-BFRREST reduces mechanical output and may be suitable for athletes in the later stages of injury rehabilitation or undertaking demanding training blocks, which require greater emphasis on internal (i.e., physiological stress) rather than external (i.e., mechanical output) loading. Declaration: My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of this abstract.

Acute performance, physiological and perceptual responses to repeated-sprint exercise with continuous or intermittent blood flow restriction

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