Brendan Scott

Background
Multiple sessions of walking with blood flow restriction (BFR) of the legs can improve cardiovascular fitness, muscle strength and hypertrophy in older adults. However, it is unclear whether BFR impairs walking balance acutely, potentially increasing falls risk during BFR training for this at-risk population.

Research Question
Does bilateral BFR of the legs acutely worsen walking balance of older adults?

Methods
Ten older adults (mean age: 73, SD: 3 y) walked for 10 min on a treadmill at 50 %, 60 % and 70 % of their fast walking speed, with 10 cm-wide cuffs on the proximal thigh of both legs inflated to 0 % (no cuff), 40 % or 60 % of arterial occlusion pressure. We measured four characteristics of walking balance which were selected a priori and combined into a gait quality index predictive of future falls in older adults: autocorrelation of vertical accelerations; magnitude and harmonicity of sideways accelerations; and magnitude of the dominant period of forwards accelerations.

Results
Walking balance worsened with BFR, independent of walking speed, for all outcomes except the magnitude of the dominant period of forwards accelerations, with worse balance observed with increasing cuff pressure. Compared to no BFR, gait quality declined 12 % when walking with 50 % occlusion and declined 20 % with 60 % occlusion (p < 0.001).

Significance
Our findings suggest that BFR results in poorer acute walking balance, with a dose-response relationship for cuff pressure. Supervised walking trials are warranted to further assess the safety of BFR training in community settings and whether these balance-related changes may stimulate beneficial chronic balance adaptations.

Davids, CJ, Vasiljevic, I, Katsifolis, A, Suppiah, H, James, LP, and Scott, BR. Explaining the variance in repetitions-in-reserve after low-load blood flow restricted resistance exercise. J Strength Cond Res XX(X): 000–000, 2025—Low-load resistance exercise with blood flow restriction (LL-BFR) is prescribed using standardized protocols (e.g., 30, 15, 15, 15 repetitions at 20–40% 1-repetition maximum). However, considerable variance exists in proximity to muscular failure under these guidelines, potentially affecting the adaptive stimulus. This study aimed to evaluate the variability in LL-BFR performance and identify factors influencing this variance. In addition, the accuracy of a subjective autoregulation strategy was evaluated during LL-BFR. Twenty recreationally active adults (12 men, 8 women) completed a leg press LL-BFR protocol, a local muscular endurance (LME) task, and conditioned pain modulation (CPM) assessments. Results revealed significant interindividual differences in the number of additional repetitions completed beyond the prescribed 15 repetitions in the final set of LL-BFR (19 ± 12, range 4–47). Local muscular endurance capacity ( r = 0.63, p = 0.003) and relative CPM response ( r = 0.50, p = 0.026) were key predictors of this variance, explaining 56% of the variability. In addition, subjects tended to underestimate repetitions-in-reserve (RIR) during LL-BFR (RIR error: 12 ± 11), reducing the accuracy of subjective autoregulation strategies. These findings suggest that higher LME and greater pain modulation capacity allow individuals to complete more repetitions before failure, resulting in a heterogeneous stimulus when using fixed LL-BFR protocols. Practitioners should consider LME and pain modulation when prescribing LL-BFR and may need to adjust loads or repetitions to ensure proximity to failure. Autoregulation using RIR should be applied cautiously, with predictions made closer to task failure for accuracy.

This study examined whether adding blood flow restriction (BFR) to small-sided games (SSG) augments cardiorespiratory/anaerobic adaptations and lower-limb muscular performance in well-trained male collegiate basketball players. Twenty-four atheletes (age: 21.0 ± 1.6 years) were randomized to either an experimental (SSG+BFR; 100–130% of leg systolic pressure) or a control group (SSG; without BFR) and completed eight 3 vs. 3 player-SSG sessions over four weeks (4 sets of 3–4.5-min bouts; 3-min rest intervals). Peak aerobic power, Peak oxygen uptake [VO2peak], Wingate 30-s peak/mean power, lower-limb performance (back-squat 1RM, countermovement-jump [CMJ] height/power, T-test, 30-m sprint, repeated-sprint ability [RSA best/mean and decrement score]) were assessed pre- and post-intervention. Linear mixed-effects models were used to test group, time, and group × time effects. The SSG+BFR group had greater improvements in Peak aerobic power than SSG (+9.5% vs. +4.5%; p = 0.035). The SSG+BFR group also significantly improved Wingate mean power, countermovement jump height, and repeated sprint ability best time (+4.6%, +6.8%, and −1.1%, respectively), while the SSG group showed no significant changes (p = 0.573). Both groups showed comparable improvements in VO2peak (+6.4% and +4.4% in SSG+BFR and SSG, respectively). Back-squat 1RM increased over time without between-group differences. T-test performance favored SSG+BFR (group effect). These findings demonstrate that adding BFR to four weeks of 3 vs. 3 player-basketball SSG provides additional performance benefits by further enhancing cardiorespiratory and anaerobic outcomes, jump height and repeated sprint ability compared to SSG alone.

To compare the physiological and perceptual responses during fixed‐power and perceptually regulated cycling, both without and with blood flow restriction (CONPWR, BFRPWR, CONRPE and BFRRPE). Twelve recreationally active men cycled for 10 min at the power corresponding to the first ventilatory threshold or, for CONRPE and BFRRPE, the perceived exertion level reported during CONPWR. Blood flow restriction was set at 60% of estimated arterial occlusion pressure. Ventilatory measures and heart rate were averaged into 2‐min blocks. Perceived exertion, effort, muscular discomfort and cuff pain were recorded every 2 min (0–10 scale). Blood lactate was measured pre‐exercise, post‐exercise, and 2 min post‐exercise. The BFRPWR trial elicited greater physiological and perceptual responses compared to all other conditions. Oxygen consumption during BFRRPE was lower than CONPWR (−19.2 ± 20.6%, p < 0.001) and CONRPE (−6.7 ± 9.3%, p = 0.007). Heart rate during CONPWR was greater than BFRRPE (8.2 ± 9.8%, p < 0.001) and CONRPE (9.4 ± 6.5%, p < 0.001). Blood lactate concentration was not different between CONPWR, CONRPE and BFRRPE; yet was greater during fixed‐power compared to fixed‐RPE trials (31.5 ± 25.6%, p < 0.001). Muscular discomfort was not different between BFRRPE and CONPWR (2.4 ± 1.1 au), yet both were greater compared to CONRPE (1.8 ± 1.5 au, p < 0.001). Cuff pain was greater during BFRPWR (3.3 ± 1.7 au) compared to BFRRPE (2.2 ± 1.1 au, p < 0.001). Prescribing aerobic BFR cycling at a fixed power output increases physiological strain, yet discomfort and pain are also heightened, which may limit its use in healthy adults. The fixed‐RPE method appears to balance the physiological and perceptual demands and thus could be a viable alternative if a fixed power output approach is intolerable.

The purpose of this study was to characterise how blood flow restriction (BFR) exercise is utilised by practitioners in high-performance sports settings. Participants (n = 154) engaged with the questionnaire, of which 123 provided data about their use of BFR with athletes in high-performance sports settings. The main findings indicated that BFR was primarily used for injury rehabilitation (81.3% of practitioners) or supplementary to traditional strength and conditioning programs for muscle hypertrophy (80.4%), limiting loss of muscle mass (71.9%), or muscle strengthening (51.6%). Participants used BFR with both team and individual sports, but with only a small subset of the athletes they worked with (65% of practitioners used BFR with less than 25% of their athletes). Cuff pressures were prescribed using both measured individualised occlusion pressures (56.1%) and arbitrary set pressures (52.8%). Despite practitioners’ awareness of contraindications and the need for screening, formal screening tools were underutilised (55.7% of practitioners did not use a screening tool for clearance to use BFR). Ultimately, BFR exercise was largely prescribed in line with established guidelines, although the application of individualised cuff pressures and health screening processes may require further attention from practitioners in high-performance sports.

In this retrospective cohort study, we examined maximal intensity periods (MIPs) for a broad range of movement characteristics during international field hockey. Further, we examined the intensity of near-peak periods, and whether peak demands for different movement characteristics occurred simultaneously. Player movement data from 28 Australian elite male field hockey players were obtained via wearable tracking devices in four international tournaments over 13 months (n = 393 player-matches). MIPs were identified via the rolling-sum method for mean speed, high-speed distance (> 5 m·s
), accelerations (> 2.5 m·s
), decelerations (< - 2.5 m·s
) and high-speed cuts (45° change of direction and > 5 m·s
) across eight epochs (range: 5 s-5 min). Random effects linear mixed models were used to estimate means for each movement characteristic, with random intercepts fitted for players and matches. Mean speed was ∼80% higher during the 1 min MIP (210 m·min
) than the match average (116 m·min
) and players regularly reached high mean speeds (for instance, the 10th most intense minute was still ∼44% above match average). High-speed distance, accelerations and decelerations accumulated > 5x faster during the 1 min MIP for those variables than the match average and high-speed cuts occurred with ∼10x greater frequency. During the 1 min MIP for total distance, all other movement characteristics were less than 40% of the 1 min MIP for that variable (except high-speed distance: 76%). Match averages substantially underestimate the MIPs of elite field hockey. Practitioners should consider analysing the peak periods of matches, with a focus on high-intensity movements, to inform monitoring and prescription of team sport-specific training.

Grant, WM, Goods, PSR, Wall, BA, Davids, CJ, Narang, BJ, Debevec, T, and Scott, BR. Validity and test-retest reliability of repetitions-in-reserve across different low-loads in the barbell bench press with blood flow restriction. J Strength Cond Res XX(X): 000-000, 2025-Repetitions-in-reserve (RIR) allows the standardization of effort between individuals during resistance training. This study investigated the validity and reliability of predicting RIR during low-load resistance training with blood flow restriction (BFR). Twenty subjects were assessed for bench press one-repetition maximum (1RM), before 4 experimental trials (20, 30, 30, 40% 1RM) comprising 4 sets (30, 15, 15, 15 repetitions; 30 seconds rest) with continuous BFR at 60% arterial occlusion pressure. After 15 repetitions in the final set, subjects estimated RIR before continuing the set to failure. Differences between estimated RIR and actual repetitions to failure were calculated (RIRerror). Test-retest reliability of RIRerror was determined from repeated 30% 1RM trials using intraclass correlation coefficients (ICC) and coefficients of variation (CV). Differences and associations were assessed by repeated measures ANOVA and correlational analyses. The fewest fourth set repetitions were performed at 40% 1RM (median [interquartile range] = 8 [5-16] repetitions), followed by 30% 1RM (30 [19-37]) and 20% 1RM (90 [53-114]). RIRerror was significantly higher with 20% 1RM (52 [23-76]) than 30% 1RM (9 [2-15]; p < 0.001) but was not analyzed at 40% 1RM (because 14/20 subjects completed ≤15 repetitions). Repetitions-in-reserve predictions were moderately reliable (ICC: 0.980, CV: 13.6%), but with wide limits of agreement (-7 to 7 repetitions). Number of fourth set repetitions was almost perfectly correlated with RIRerror (R2 = 0.90-0.94). Repetitions-in-reserve should not replace 1RM training prescriptions for low-load BFR. Results suggest that 30% 1RM is an appropriate load to begin with for trained individuals using a 75-repetition BFR scheme.

Purpose : To explore how graded hypoxia affects perceptual sensations during heart-rate (HR) -clamped cycling using qualitative methods.

Methods : Sixteen trained males cycled for 60 minutes on separate visits, with their HR clamped at 80% of their first ventilatory threshold across simulated altitudes of 2500 m, 3000 m, 3500 m, and 4000 m and in normoxia. After each session, an ∼10-minute structured interview was conducted to gather insights into participants’ perceptions of the exercise under each condition. Interview transcripts were analyzed for key themes, which were presented in a pen profile.

Results : At 4000 m, 5 participants perceived light-headedness and 2 had difficulty focusing, which were not experienced at lower altitudes. Difficulty breathing increased progressively with hypoxic severity, from 1 report in normoxia to 9 at 4000 m. Limb discomfort was consistently reported across all conditions.

Conclusion : Despite comparable physiological responses during HR-clamped cycling, hypoxia severity influenced selected perceived sensations (ie, difficulty focusing, difficulty breathing, and light-headedness). These effects should be considered when selecting the desired hypoxic severity for HR-clamped cycling.

Blood flow restriction (BFR) combined with low work rate exercise can enhance muscular and cardiovascular fitness. However, whether neural mechanisms mediate these enhancements remains unknown. This study examined changes in corticospinal excitability and motor cortical inhibition following arm cycle ergometry with and without BFR. Twelve healthy males (24 ± 4 years) completed four, randomized 15‐min arm cycling conditions: high work rate (HW: 60% maximal power output), low work rate (LW: 30% maximal power output), low work rate with BFR (LW‐BFR) and BFR without exercise (BFR‐only). For BFR conditions, cuffs were applied around the upper arm and inflated to 70% of arterial occlusion pressure continuously during exercise. Single‐pulse transcranial magnetic stimulation was delivered to left primary motor cortex (M1) to elicit motor‐evoked potentials (MEP) in the right biceps brachii during a low‐level isometric contraction. MEP amplitude and cortical silent period (cSP) duration were measured before and 1, 10 and 15 min post‐exercise. MEP amplitude increased significantly from baseline to Post‐10 and Post‐15 for both the HW (both z  < −7.07, both P  < 0.001) and LW‐BFR conditions (both z  < −5.56, both P  < 0.001). For the LW condition without BFR, MEP amplitude increased significantly from baseline to Post‐10 ( z  = −3.53, P  = 0.003) but not Post‐15 ( z =  −1.85, P  = 0.388). The current findings show that HW arm cycling and LW‐BFR led to longer‐lasting increases in corticospinal excitability than LW arm cycling alone. Future research should examine whether the increased corticospinal excitability is associated with the improvements in muscle strength observed with BFR exercise. A mechanistic understanding of BFR exercise improvement could guide BFR interventions in clinical populations.
What is the central question of this study? Does low work rate arm cycling with blood flow restriction (BFR) lead to an increase in corticospinal excitability and decrease in cortical inhibition that is comparable to high work rate arm cycling and greater than low work rate arm cycling and BFR without exercise? What is the main finding and its importance? Unrestricted high work rate arm cycling and low work rate arm cycling combined with BFR led to longer lasting increases in corticospinal excitability than low work rate arm cycling alone. Future research is needed to examine whether the increased corticospinal excitability is associated with the improvements in muscle strength observed with BFR exercise.