Effect of sprint interval cycling with blood flow restriction on capillary blood lactate, cognitive function and perceptual response: a randomized controlled trial

Regular participation in physical activity can slow age-related functional and cognitive decline but many have cited a lack of time and energy as key barriers to exercise adherence. Hence, exercises with lower time commitment may appeal to sedentary individuals or working adults who perform insufficient physical activity. Sprint interval exercise with blood flow restriction (BFR-SIE) is a time-efficient exercise modality that may augment cognitive gains through enhanced metabolic stimulation and cerebrovascular alterations. Therefore, we aimed to investigate the effect of BFR-SIE on capillary blood lactate, cognition and perceptual response in healthy young adults. This study involved randomized controlled trials with unblinded crossover design. 18 participants (10 males; 8 females; age 26.4 ± 3.3 years; body mass 60.5 ± 12.6 kg; height 1.65 ± 0.07 m) completed sprint interval cycling involving six sets of 10 s all-out sprints with 1-min rest intervals, performed (1) with BFR applied at 50% occlusion pressure on both thighs (BFR-SIE), and (2) without BFR (SIE). Before and after each session, capillary blood lactate level was assessed, and cognitive assessments (Digit Span and Stroop test) were performed to evaluate working memory, selective attention, and executive function. Cycling power output was measured during sprints. Both BFR-SIE and SIE groups displayed comparable improvements in Stroop reaction times while task accuracies were largely unaltered for Stroop and Digit Span tests (p > 0.05). Both groups experienced similar increases in blood lactate levels despite a higher peak power output observed in SIE (366 ± 118 W vs. 336 ± 119 W; p < 0.001). Despite a lower power output during BFR-SIE, participants reported a higher mean rating of perceived exertion (5.3 ± 1.9 vs. 4.9 ± 1.8; p = 0.003). A single bout of sprint interval exercise with BFR did not further increase capillary blood lactate levels nor benefit cognition, likely due to the counteracting effect of higher perceived exertion. While BFR remains a promising tool to amplify the physiological responses to exercise, it may be suboptimal to implement for self-paced exercise, maximal exercise or exercise to exhaustion.ISRCTN registration: ISRCTN16365146; retrospectively registered on 07 Oct 2025.