Running with and without blood flow restriction on fatigability and biomechanics: a cross-over trial.

Running assessments are frequently conducted without inducing fatigability because achieving true exhaustion in athletes can be both time consuming and physically demanding. Blood flow restriction (BFR) presents a potential solution by reducing time-to-exhaustion. To determine whether running with BFR (1) accelerates fatiguability compared to standard running and (2) influences running spatiotemporal parameters, including step frequency, step length, contact time, flight time, and duty factor. Sixteen participants (11 men, 5 women) completed two cross-over running trials until exhaustion under two conditions: control and 80% occlusion BFR. Time-to-exhaustion and heart rate were recorded as well as pre/post run maximal voluntary isometric contractions for knee flexors, knee extensors, and ankle plantar flexors. Running spatiotemporal parameters were measured at 65% of maximal aerobic speed both before and after exhaustive running. The BFR protocol significantly shortened time-to-exhaustion (7 min 51 s ±2 min 54 s vs. 24 min 02 s ±12 min 10 s in control, p < .001). Heart rate at exhaustion was lower in the BFR condition (169.5 ± 19.0 vs. 188.1 ± 8.9 bpm, p = .001). Post-run knee flexors strength declined similarly in both protocols (~21%), indicating comparable neuromuscular fatigability despite the shorter BFR running time. None of the spatiotemporal parameters differed significantly between conditions (p > .074). Running with BFR accelerates fatigability without significantly affecting running spatiotemporal parameters.