Tissue oxygenation in response to low-load and high-load back squats with continuous blood flow restriction in...

To determine muscle oxygenation with continuous blood flow restriction (BFR) training in high load (HL), 80% one-repetition maximum (1RM) and low load (LL), 30% 1RM squat exercises. In week-2 of a 4-week resistance training programme as part of their 3-set training routine, two groups of athletes (n = 4 each), one performing HL training with low cuff pressure (20% arterial occlusion pressure (AOP)), the other LL training with high cuff pressure (60% AOP) had muscle oxygenation assessed with near-infrared spectrophotometry (NIRS), arterial oxygen saturation (SPO₂), heart rate (HR), barbell velocity and ratings of perceived exertion (RPE) during barbell back squats (BBS). Changes in the vastus lateralis oximetry were compared to pre- and post-training squat (1RM). Across athletes, there were significant associations between two pre-set-3 exercise variables and post-training 1RM, Tissue Saturation Index (TSI) (R² = 0.92, p < 0.0002) and HHb concentration (R² = 0.79, p < 0.003). Generalised regression models indicated that TSI % and HHb concentrations before and after set 3 timepoints were significant predictors of post-training 1RM in the LL group (R² = 0.99, BIC = -24.9). Well-tolerated continuous LL-BFR training provided greater increases in strength than HL-BFR in athletes.