Four weeks of blood flow restriction between high-intensity interval repetitions improves intermittent exercise performance in trained cyclists

Blood flow restriction (BFR) alters acute physiological responses when applied during recovery between high-intensity interval training (HIIT) repetitions, but its chronic effects on intermittent performance are unclear. This study investigated whether 4-weeks of BFR during HIIT recovery enhances physiological measures and intermittent performance in trained cyclists. Ten trained male cyclists (mean ± SD, age: 27.5 ± 6.8 years; body mass: 76.4 ± 14.2 kg; incremental-test V˙O 2PEAK : 59.8 ± 7.1 mL·kg −1 ·min −1 ) completed eight HIIT sessions across 4-weeks, each comprising six 30-s efforts at 85% of maximal 30-s sprint power (562 ± 94 W), separated by 4.5-min recovery phases. Participants were assigned to BFR (n = 5; 2-min bilateral thigh cuff inflation at 200 mmHg during recovery) or control (n = 5; passive recovery). Pre- and post-intervention assessments included a maximal incremental test, 30-s sprint test, and intermittent cycling test. Two-way ANOVAs revealed significant condition × time interactions. Compared with controls, the BFR group showed greater improvements in power at lactate threshold (20 ± 15 W; 7.4 ± 5.4% vs −2 ± 10 W; −0.5 ± 3.6%), 30-s mean power output (50 ± 23 W; 7.5 ± 4.1% vs 10 ± 27 W; 1.5 ± 4.1%), intermittent test duration (117 ± 64 s; 59.9 ± 56.7% vs 6 ± 64 s; −4.3 ± 20.6%), and V˙O 2PEAK during the intermittent test (4.4 ± 1.2 mL·kg −1 ·min −1 ; 7.4 ± 2.1% vs 1.3 ± 2.1 mL·kg −1 ·min −1 ; 1.8 ± 3.2%) (all p < 0.05). These findings suggest that BFR during HIIT recovery phases enhances physiological measures and intermittent performance more than HIIT alone.