ABSTRACT:Howard, MA, Lubiak, SM, Schmidt, JT, Stray-Gundersen, S, Hirsch, KR, Trevino, MA, Hammer, SM, Dinyer-McNeely, TK, Bergstrom, HC, Keller, JL, and Hill, EC. Passive blood flow restriction accelerates muscle recovery after exercise-induced muscle damage in healthy, recreationally active females. J Strength Cond Res XX(X): 000-000, 2026-The purpose of this investigation was to examine the effects of passive blood flow restriction (pBFR) on indices of exercise-induced muscle damage (EIMD) following a muscle-damaging protocol. Eighteen females completed 6 visits occurring at the same time of day (±2 hours). Muscle damage was elicited by performing 3 sets of 25 maximal, unilateral, isokinetic (60·s-1), concentric-eccentric leg extensions on each leg. Each leg was then randomly assigned to receive pBFR (80% of total arterial occlusion pressure) or sham (20 mmHg) at 0, 24, 48, 72, and 96 hours post-EIMD. Indices of EIMD (muscle soreness [0-10 visual analog scale], limb circumference, range of motion [ROM], pain pressure threshold, and maximal voluntary isometric contraction [MVIC] torque) were assessed before EIMD (baseline) and at 0, 24, 48, 72, and 96 hours. Separate 2 (Condition [pBFR and sham]) × 6 (Time [baseline, 0, 24, 48, 72, and 96 hours]), repeated-measures ANOVAs were performed. Collapsed across Condition, muscle soreness increased post-EIMD and partially recovered at 72 and 96 hours (change from baseline [Δ]; Δ2.3 ± 2.3 au and Δ1.4 ± 1.5 au, respectively). Limb circumference increased in both conditions post-EIMD and recovered by 24 hours (pBFR: Δ0.4 ± 1.8 cm; sham: Δ0.5 ± 2.2 cm). ROM recovered sooner for pBFR (24 hours; Δ-6.1 ± 8.9°) than sham (24 hours; Δ-9.2 ± 9.4°), and ROM was greater for pBFR than sham at 48 hours post-EIMD. Pain pressure threshold was greater, collapsed across Time, for pBFR (4.40 ± 1.62 kgf) than sham (4.12 ± 1.63 kgf). Like ROM, MVIC torque recovered sooner for pBFR (24 hours; Δ-14.9 ± 25.3 Nm) than sham (24 hours; Δ-33.9 ± 22.1 Nm). Applying pBFR after EIMD resulted in a faster rate of return for MVIC and ROM in females, suggesting that pBFR may serve as an effective strategy to facilitate recovery of muscle function.

Although acute resistance exercise (RE) has been proposed to influence cognitive flexibility and underlying neural mechanisms, it remains unclear whether these effects vary across loading strategies and whether exercise-induced prefrontal hemodynamic responses translate into cognitive outcomes. The present study examined (1) prefrontal cortex (PFC) oxygenated hemoglobin (O2Hb) responses across exercise sets and conditions, (2) the effects of low-load (LL), LL with blood flow restriction (BFR), and high-load (HL) RE on task-switching performance, and (3) whether exercise-related PFC O2Hb responses were associated with pre- to post-exercise changes in task-switching performance. Thirty physically active adults completed three randomized, counterbalanced RE conditions consisting of four sets of barbell squats. LL was performed at 30% one-repetition maximum (1RM) with and without BFR, whereas HL was performed at 70% 1RM. Cognitive flexibility was assessed pre- and post-exercise using a modified Stroop task, indexed by switch-cost reaction time (RT) and accuracy. PFC O2Hb was assessed using functional near-infrared spectroscopy during exercise and expressed as changes from the resting baseline for each set (Sets 1-4). PFC O2Hb increased across sets, rising from Set 1 to Set 3 before plateauing, with no differences observed across conditions. Switch cost RT and accuracy did not improve from pre- to post-exercise, and no differences across conditions were detected. PFC O2Hb during the final set was not associated with changes in switch cost. These findings suggest that although acute RE elicits robust increases in prefrontal hemodynamic activity, such responses may not translate into acute improvements in cognitive flexibility.

Purpose:To examine muscle oxygenation during running with and without blood flow restriction (BFR). Methods:Fifteen aerobically trained males randomly completed four, three-minute running bouts at 70%BFR, 80%BFR, and 90%BFR of their top speed with BFR and 100%NOBFR of their top speed without BFR. Oxygenated hemoglobin (O2Hb), deoxygenated Hb (HHb), total Hb (tHb), Hb difference (HbDiff) and muscle tissue oxygenation (StO2) were assessed continuously throughout the running bouts. Separate two-way, 4 (Intensity [70%BFR, 80%BFR, 90%BFR, 100%NOBFR]) × 3 (Time [120, 150, and 180 s]), repeated-measure ANOVA models were constructed to examine O2Hb, HHb, tHb, HbDiff, and StO2 responses. Results:O2Hb decreased (120- [65.25 ± 6.58%] > 150-s [63.72 ± 6.75%]), while HHb increased (120- [14.4 ± 12.55%] < 150- [16.91 ± 12.6%] < 180-s [18.26 ± 12.87%]) (P < 0.001). tHb was similar across time (P = 0.159) and between intensities (P = 0.454). HbDiff decreased (120- [73.56 ± 6.54%] > 150- [71.66 ± 6.61%] > 180-s [70.98 ± 6.93%]). StO2 decreased and then plateaued (120- > 150- and 180-s) during the 70%BFR (51.87 ± 5.09% > 51.20 ± 5.37% and 51.02 ± 5.21%) (P = 0.004), 80%BFR (52.2 ± 3.93% > 51.34 ± 4.17% and 51.01 ± 4.09%) (P = 0.008), and 100%NOBFR (51.69 ± 4.6% > 50.84 ± 4.87% and 50.62 ± 4.89%) (P < 0.001) bouts, while there were no differences for 90%BFR (P > 0.05). Conclusions:Submaximal running with BFR induced similar responses as maximal running without, despite large differences (i.e., ≤30%) in running speed.

ABSTRACT:Lubiak, SM, Howard, MA, Schmidt, JT, Shah, NM, Patel, NN, Prajapati, AJ, Herring, EK, and Hill, EC. Ischemic preconditioning does not attenuate reductions in rate of torque development after fatiguing resistance exercise. J Strength Cond Res 40(7): e676-e683, 2026-The purpose of this investigation was to examine the acute effects of ischemic preconditioning (IPC) on indices of rate of torque development (RTD) and peak torque (PT) after fatiguing resistance exercise. Twelve college-aged females randomly completed 3 cycles of IPC at low (20 mmHg [IPCSHAM]), moderate (80% of total arterial occlusion pressure [IPC80]), and high (220 mmHg [IPC220]) pressures. Each cycle consisted of 5 minutes at the assigned pressure followed by 5 minutes of zero pressure. After IPC, subjects performed one-set to volitional failure of unilateral, isotonic, concentric-only leg extension muscle actions at 30% of 1-repetition maximum. Two maximal voluntary isometric contractions (MVICs) were performed before and immediately after the fatiguing exercise protocol to derive RTD at early (0-100 ms; RTD100), late (0-200 ms; RTD200), and peak (0-peak; RTDPK), as well as PT from the highest pretest and post-test MVIC. Separate 2-way, 3 (Pressure [IPCSHAM, IPC80, and IPC220]) × 2 (Time [Pretest, Post-test]), repeated-measures analysis of variance were performed to examine mean differences. Collapsed across Pressure, RTD100 (-113.9 Nm·s-1; p = 0.045), RTD200 (-94.5 Nm·s-1; p = 0.008), RTDPK (-157.0 Nm·s-1; p = 0.028), and PT (-15.2 Nm; p = 0.002) decreased from pretest to post-test. There were no significant interactions (p = 0.463-0.934) or main effects of Pressure (p = 0.235-0.581). Applying IPC at various pressures did not attenuate reductions in RTD or PT after fatiguing resistance exercise. Thus, coaches and practitioners may consider alternative exercise adjuncts or strategies to attenuate resistance exercise fatigue-induced performance reductions.

ABSTRACT:Howard, MA, Rivera, PM, Lubiak, SM, Proppe, CE, Schmidt, JT, Rolnick, N, Shobe, ED, Fraifer, TL, and Hill, EC. Uniform neuromuscular responses across varied blood flow restriction training strategies. J Strength Cond Res 40(3): 304-310, 2026-The purpose of this investigation was to assess neuromuscular responses during acute bouts of resistance exercise with low-load blood flow restriction (LLBFR) performed with a 75-repetition protocol (75-rep; 1 × 30, 3 × 15), 3 sets to failure (3×), and 1 set to failure (1×). Seventeen recreationally active females randomly completed 75-rep, 3×, and 1× protocols consisting of unilateral, submaximal (30% of maximal voluntary isometric contraction), isokinetic (90°·s -1 ), leg extension muscle actions. A greater number of repetitions were performed during set 1 of the 1× protocol (59.5 ± 35.1) compared with the 75-rep protocol (30.0 ± 0.0), and more total repetitions were performed in the 3× protocol (85.2 ± 42.2) compared with the 1× protocol (59.5 ± 35.1). Surface electromyographic (sEMG) amplitude (AMP) progressively increased and then plateaued after 2 sets for the 75-rep protocol (118.3 ± 31.4% to 185.9 ± 85.3%; p = 0.043) and after 1 set of the 3× protocol (119.6 ± 8.6% to 206.3 ± 84.1%; p = 0.003). In addition, sEMG mean power frequency (MPF) decreased and then plateaued after 3 sets of the 75-rep protocol (99.8 ± 3.5% to 88.8 ± 11.7%; p = 0.012) and after 1 set of the 3× protocol (101.0 ± 8.2% to 84.4 ± 18.9%; p < 0.001). The changes in sEMG AMP and sEMG MPF across multiple sets (i.e., 75-rep and 3×) never exceeded the changes observed after the 1× protocol. Despite variations in set and repetition schemes, performing just 1 set of LLBFR to failure was sufficient to maximize acute neuromuscular responses. This highlights the efficiency of a single-set LLBFR protocol as a time-effective option for athletes and practitioners.

Objective.The use of ischemic preconditioning (IPC) may delay the onset of fatigue, however, its impact on mean power (MP) and neuromuscular function remains unclear. The purpose of this investigation was to examine the impact of IPC prior to an acute bout of fatiguing resistance exercise on MP, surface mechanomyography amplitude (sMMGAMP), and sMMG MP frequency (sMMGMPF).Approach.Nineteen males randomly completed IPC on separate visits at a low (20 mmHg), moderate individualized (80% of total arterial occlusion pressure), and a supra-systolic absolute (220 mmHg) pressure. Following IPC, participants performed one-set to failure of unilateral (i.e. one leg), isotonic (i.e. constant load), concentric-only leg extensions with a submaximal load (i.e. 30% of one-repetition maximum). MP, sMMGAMP, and sMMGMPFwere assessed from concentric peak torque muscle actions performed at an angular velocity of 90°·s-1prior to and immediately following the bout of exercise. Each dependent variable was analyzed with Bayesian multilevel models (i.e. random intercepts and slopes) and the fixed effects are reported as the mean difference (Meandiff) and the 95% high-density interval (95% HDI).Main Results.There were no significant interactions or main effects of Condition for any of the dependent variables. Following the one-set to failure, however, MP (Meandiff= 68.60 ± 1.67 W; 95% HDI: 53.80-83.60), sMMGAMP(Meandiff= 0.58 ± 0.04 m·s-2; 95% HDI: 0.26-0.91), and sMMGMPF(Meandiff= 1.35 ± 0.13 Hz; 95% HDI: 0.32-2.39) decreased.Significance.The use of IPC prior to an acute bout of fatiguing resistance exercise did not attenuate the fatigue-induced decreases in MP, sMMGAMP, or sMMGMPF. These responses may be attributed to the accumulation of metabolic byproducts, decreases in muscular compliance, and/or alterations in the global firing rate of the unfused activated motor units.

BACKGROUND:Blood flow restriction (BFR) implemented during aerobic exercise has been shown to alter cardiopulmonary responses under intensity-matched conditions, but its effects relative to maximal running speed and the gas exchange threshold (GET) remain unclear. The purpose of this investigation was to examine cardiopulmonary (oxygen consumption [V̇O2] and carbon dioxide production [V̇CO2]) responses during submaximal running with BFR relative to maximal running without BFR and the GET. METHODS:Fifteen aerobically trained females completed a custom ramp protocol to determine peak running speed and GET. Participants randomly completed four, three-minute running bouts at 70%BFR, 80%BFR, and 90%BFR of their top speed with BFR and 100%NOBFR of their top speed without BFR. Separate Bayesian repeated-measure models were performed to examine differences in V̇O2 and V̇CO2 during the final minute of the bouts. RESULTS:V̇O2 largely increased across bouts but was similar between the 80%BFR and 90%BFR (Meandiff=-2.26±-0.44 mL·kg-1·min-1) bouts as well as the 90%BFR and 100%NOBFR (Meandiff=-2.54±0.03 mL·kg-1·min-1) bouts. V̇CO2 also increased across bouts and was similar between the 90%BFR and 100%NOBFR (Meandiff=-0.25±-0.02 L·min-1) bouts. Relative to GET, V̇O2 and V̇CO2 was greater during each bout (GET < 70%BFR, 80%BFR, 90%BFR, and 100%NOBFR). CONCLUSIONS:Pulmonary gas exchange during submaximal running with BFR was comparable to maximal running without BFR (i.e., 90%BFR and 100%NOBFR) and greater than speed-matched running (i.e., relative to GET). Thus, BFR may serve as a training adjunct to lower the intensity (i.e., ≤10%) relative to the GET.

This investigation examined the effects of passive blood flow restriction (pBFR) on indices of exercise-induced muscle damage (EIMD) in recreationally active males. Fifteen males completed six consecutive visits (±2 hours). Participants completed 3 × 25 maximal, unilateral, isokinetic (60°·s-1), concentric-eccentric leg extensions on both legs. Each leg was randomly assigned to receive pBFR (80% arterial occlusion pressure) or sham (20 mmHg) at 0, 24, 48, 72, and 96 hours post-EIMD. Perceived muscle soreness, range of motion (ROM), pain pressure threshold (PPT), concentric peak torque (CPT), and maximal voluntary isometric contraction (MVIC) torque were assessed and analyzed using separate linear mixed-effects models. Perceived muscle soreness increased at 24 hours (mean difference [meandiff] = 4.9 au; p < 0.001) and recovered by 96 hours (p = 0.482), with no differences between conditions (p = 0.450). ROM (meandiff = -3.1°; p = 0.040), PPT (meandiff = -1.63 kgf; p < 0.001), CPT (meandiff = -27.7 Nm; p < 0.001), and MVIC torque (meandiff = -30.8 Nm; p < 0.001) decreased at 24 hours, with recovery occurring between 48-96 hours. Condition-specific differences were observed for ROM (meandiff = 2.5°; p < 0.001), PPT (meandiff = 0.49 kgf; p = 0.005), CPT (meandiff = 6.2 Nm; p = 0.020), and MVIC torque (meandiff = 7.1 Nm; p = 0.044), which were greater in pBFR than sham. These findings suggested that pBFR may reduce impairments in ROM, PPT, CPT, and MVIC torque following EIMD, despite a similar recovery trajectory between conditions.

To examine the acute effects of ischemic preconditioning (IPC) implemented at a low (20 mmHg [IPCSHAM]), moderate (80

Resistance exercise can attenuate muscular impairments associated with multiple sclerosis (MS), and blood flow restriction (BFR) may provide a viable alternative to prescribing heavy training loads. The purpose of this investigation was to examine the progression of upper and lower body low-load (30

Resistance-trained adults may present worse arterial stiffness and other hemodynamic outcomes than adults mainly engaging in aerobic exercise. Pulse wave velocity (PWV) evaluates arterial stiffness, and pulse wave analysis provides various hemodynamic measures such as augmentation index (AIx 75) and central and peripheral pulse pressures (cPP and pPP). Biological sex may affect the anticipated training history-specific responses. Therefore, the purpose was to examine training history- and biological sex-related differences in PWV, AIx 75, cPP, and pPP in young men and women. Fifty adults (27 men, 33 resistance- and 17 aerobic-trained) completed 2 experimental visits during which PWV, AIx 75, cPP, and pPP were quantified with a SphygmoCor device. Separate 2 (sex: male vs. female) & times; 2 (training history: resistance vs. aerobic) between-factor ANOVAs were used to examine potential mean differences. Intraclass correlation coefficients were calculated to evaluate test-retest reliability. A value of p <= 0.05 was considered statistically significant. Additional analyses included 2-way Bayesian between-factor models using Markov Chain Monte Carlo estimations to derive high-density intervals (HDI). There was no significant interaction for any outcome. For sex differences, the men exhibited significantly faster PWV (95% HDI: 0.03-0.72), whereas the women exhibited greater AIx 75. The men also exhibited greater cPP and pPP (p = 0.002 and <0.001, respectively). For training history differences, resistance training resulted in significantly (p < 0.01) greater AIx 75. All outcomes exhibited suitable reliability. Arterial stiffness was similar for adults who predominantly engage in resistance or aerobic exercise. Based on the AIx 75 findings, strength coaches should encourage aerobic training if greater vascular tone improvements are desired.

The use of blood flow restricted (BFR) running may provide an alternative to lower the running speed without compromising physiological responses that often occur during high intensity running. The purpose of this investigation was to compare the acute effects of various submaximal treadmill running speeds with BFR relative to maximal treadmill running speed without BFR on surface electromyographic amplitude (sEMGAMP), surface electromyographic mean power frequency (sEMGMPF), and muscle tissue oxygenation (StO2) responses. Thirteen college-aged females randomly completed four, three-minute treadmill running bouts at 70

OBJECTIVES:Assess the repeatability of exercise-induced hypoalgesia (EIH) following low-load resistance exercise with blood flow restriction (LL + BFR) and the magnitude of EIH following LL + BFR, high-load resistance exercise, and a control intervention 1-h after exercise. DESIGN:Crossover design. SETTING:University laboratory. PARTICIPANTS:15 females, 15 males. MAIN OUTCOME MEASURES:Pain pressure threshold and tolerance of the rectus femoris, gastrocnemius, and biceps brachii pre-exercise and 0-, 15-, 30-, 45-, and 60-min post-exercise. RESULTS:There was no significant (p = 0.211-0.741) difference in pain pressure threshold or tolerance between LL + BFR1 and LL + BFR2 suggesting that EIH following LL + BFR is repeatable. LL + BFR elicited a significant (p = 0.001-0.043) increase in local pain pressure threshold (1.57 ± 1.21-0.98 ± 1.48 Δkgf) and tolerance (1.98 ± 2.65-0.83 ± 2.15 Δkgf) up to 1-h post-exercise. High-load resistance exercise elicited a significant (p = 0.003-0.034) increase in pain pressure threshold 0-min post-exercise (1.69 ± 1.74 Δkgf) and tolerance 0- and 15-min post-exercise (2.31 ± 2.44 Δkgf; 0.56 ± 1.83 Δkgf, respectively) then returned to pre-exercise levels. LL + BFR elicited a significant (p = 0.025-0.046) increase in systemic pain pressure tolerance (0.77 ± 0.88 Δkgf) of the gastrocnemius as well as pain pressure threshold (0.53 ± 0.54 Δkgf) and tolerance (0.49 ± 1.02 Δkgf) of the biceps brachii, when collapsed across Time. CONCLUSIONS:LL + BFR may be a repeatable, effective pain management intervention that can produce prolonged EIH.

BACKGROUND:Over 25% of U.S. older adults experience chronic knee pain, which worsens with inactivity, creating a cycle of pain, disability, and sedentary behavior. However, a limited understanding of the underlying mechanisms hinders the development of effective treatments. PURPOSE:This study integrated assessments of Conditioned Pain Modulation (CPM) and motor unit control to elucidate the role of pain sensitization and neuromuscular impairments specific to chronic knee pain. METHODS:Seventy-five participants were divided into three groups: young adults (n = 25), older adults without pain (n = 30), and older adults with chronic pain (n = 20). CPM efficiency was evaluated using heat and pressure test stimuli alongside a cold-water bath conditioning stimulus. Motor unit assessments involved isometric contractions of the dominant/painful quadriceps at 50 % of maximal torque, with surface electromyographic signals recorded from the vastus lateralis. RESULTS:Independent of chronic knee pain, older adults demonstrated more efficient heat-CPM than young adults (p = 0.014, ηp2 = 0.080). The slope of the mean firing rate versus recruitment threshold relationship indicated that older adults showed greater firing rates for high threshold motor units, independent chronic knee pain (p = 0.010, ηp2 = 0.136). The y-intercept of this relationship was greater in younger versus chronic-pain older adults (p = 0.024, ηp2 = 0.111). CONCLUSION:Contrary to our hypothesis, older adults displayed more efficient heat-CPM, independent of chronic pain. Similarly, motor unit control was mostly influenced by age but not chronic knee pain. These findings suggest that age-related changes in pain modulation and motor unit behavior may play a greater role in neuromuscular function than the presence of chronic pain itself.

It is recommended to prescribe sets to volitional muscular failure (e.g., 4 sets) or a fixed repetition scheme of 75 repetitions (1 × 30, 3 × 15) in low-load resistance exercise with blood flow restriction (BFR-RE). While prior studies suggest both protocols may elicit similar muscular adaptations, the extent to which this is explained by matched exercise volume remains unclear. This systematic review and meta-analysis evaluated the number of repetitions performed during four sets of low-load BFR-RE to volitional muscular failure and compared these with the fixed 75-repetition scheme. The goal was to determine whether the two protocols yield similar total and per-set repetition volumes. On 10/31/2024, two databases (PubMed® and Scopus) were used to identify studies that applied a protocol of four sets to volitional muscular failure in BFR-RE with a load of ≤ 50

Low-load blood flow restricted (LLBFR) resistance exercise has been demonstrated to accelerate acute muscle fatigue, but these responses may be dependent upon the protocol used. The purpose of this investigation was to examine fatigue characteristics following acute LLBFR resistance exercise with a 75-repetition (75-rep; 1 × 30, 3 × 15), 3 sets to failure (3×), and 1 set to failure (1×) protocols. Sixteen women randomly performed 75-rep, 3× , and 1× LLBFR protocols consisting of unilateral, submaximal (30