Does Beta-Alanine Supplementation Potentiate Muscle Performance Following 6 Weeks of Blood Flow Restriction or Traditional Resistance Training?

We aimed to compare the effects of beta-alanine on Traditional Resistance Training (TRAD) or Blood Flow Restriction Training (BFR). METHODS: 19 subjects were randomly allocated to a Placebo (n = 10) or beta-alanine (n = 9) group. Subjects from both groups were trained unilaterally (unilateral arm curl) for six weeks, and each arm was trained using a different paradigm (BFR or TRAD). One repetition maximum (1RM) test measurements were performed before and after the strength training program. Work output was accessed as the total weight lifted (repetitions × weight lifted × sets) for the entire strength training program. RESULTS: 1RM or total weight lifted was not increased by beta-alanine supplementation. However, the TRAD-trained arm showed a significantly increased 1RM and total weight lifted compared to the BFR arm (p < 0.05). CONCLUSION: We conclude that in the short-term (6 weeks) and following the current experimental conditions, beta-alanine does not benefit BFR or TRAD in terms of total weight lifted (volume of training) or maximal strength (1RM).

Creatine supplementation combined with blood flow restriction training enhances muscle thickness and performance: a randomized, placebo-controlled, and double-blind study.

This study aimed to compare the effects of an 8-week creatine (CR) or placebo (PL) supplementation on muscle strength, thickness, endurance, and body composition employing different training paradigms with blood flow restriction (BFR) vs. traditional resistance training (TRAD). Seventeen healthy males were randomized between the PL (n = 9) and CR (n = 8) groups. Participants were trained unilaterally utilizing a within-between subject bicep curl exercise where each arm was allocated to TRAD or BFR for 8 weeks. Muscular strength, thickness, endurance, and body composition were evaluated. Creatine supplementation promoted increases in muscle thickness in TRAD and BFR compared with their placebo counterparts, however, without a significant difference between treatments (p = 0.349). TRAD training increased maximum strength (1 repetition maximum (1RM)) compared with BFR after 8 weeks of training (p = 0.021). Repetitions to failure at 30% of 1RM were increased in the BFR-CR group compared with the TRAD-CR group (p = 0.004). Repetitions to failure at 70% 1RM were increased from weeks 0-4 (p < 0.05) and 4-8 (p < 0.05) in all groups. Creatine supplementation exerted a hypertrophic effect when utilized with TRAD and BFR paradigms and increased muscle performance at 30% 1RM when utilized in conjunction with BFR. Therefore, creatine supplementation seems to amplify muscle adaptation following a BFR program. Registered in the Brazilian Registry of Clinical Trials (ReBEC), under the registration number: RBR-3vh8zgj.

Acute Physiological Responses to Moderate-Intensity Continuous, High-Intensity Interval, and Variable-Intensity Intermittent Exercise.

Purpose: This study examined acute physiological responses to moderate-intensity continuous exercise (MICE), variable-intensity intermittent exercise (VIIE), and high-intensity interval exercise (HIIE) protocol, matched for total work output in healthy adults (n = 8, age = 25.1 ± 6.0 yrs). Methods: Three experimental trials were completed in a random order. MICE was continuous exercise at 40% of peak work rate (WRpeak). VIIE consisted of sixteen 10-sec bursts at 120% WRpeak, sixteen 20-sec bursts at 60% WRpeak and recovery at 20% WRpeak interspersed throughout the protocol. HIIE consisted of eight intervals of 2 minutes at 70% WRpeak and 1 minute at 20% WRpeak. Oxygen consumption during work-intervals and time within moderate and vigorous-intensity zones determined the magnitude and duration of physiological stresses. Perceptual responses were measured by affective response and post-exercise enjoyment (PACES). Repeated-measure ANOVAs analyzed differences between trials. Statistical significance was established if p ≤ 0.05. Results: Oxygen consumption during work-intervals in VIIE was greater than MICE, but less than HIIE. VIIE and HIIE had similar duration within vigorous-intensity zone (11.1 ± 3.5 min vs. 13.5 ± 1.3 min); both were greater than MICE (4.9 ± 1.1 min). The time spent in the moderate-intensity zone was different between all trials (VIIE = 11.1 ± 2.0 min; MICE = 17.4 ± 5.2 min; HIIE = 4.9 ± 0.4 min). Affective responses were similar among all trials. Post-exercise enjoyment was greater in VIIE than HIIE; both were not different from MICE. Conclusion: These results suggests the VIIE paradigm could be a viable alternative to HIIE and MICE protocols.

Acute Responses to Cycling Exercise With Blood Flow Restriction During Various Intensities.

ABSTRACT: Lauver, JD, Moran, A, Guilkey, JP, Johnson, KE, Zanchi, NE, and Rotarius, TR. Acute responses to cycling exercise with blood flow restriction during various intensities. J Strength Cond Res 36(12): 3366-3373, 2022-The purpose of this study was to investigate the acute physiological responses during cycling at various intensities with blood flow restriction (BFR). Subjects ( N = 9; V̇ o2 peak = 36.09 ± 5.80 ml·kg -1 ·min -1 ) performed 5 protocols: high-intensity (HIGH), control (CON-90), 90% of ventilatory threshold (VT) work rate with BFR (90-BFR), 70% of VT with BFR (70-BFR), and 30% V̇ o2 peak with BFR (30-BFR). Protocols consisted of five 2-minute work intervals interspersed with 1-minute recovery intervals. Blood flow restriction pressure was 80% of limb occlusion pressure. V̇ o2 , muscle excitation, tissue oxygen saturation (StO 2 ), discomfort, and level of perceived exertion (RPE) were assessed. Muscle excitation was higher during HIGH (302.9 ± 159.9 %BSL [baseline]) compared with 70-BFR (99.7 ± 76.4 %BSL) and 30-BFR (98.2 ± 70.5 %BSL). StO 2 was greater during 90-BFR (40.7 ± 12.5 ∆BSL), 70-BFR (34.4 ± 15.2 ∆BSL), and 30-BFR (31.9 ± 18.7 ∆BSL) compared with CON-90 (4.4 ± 11.5 ∆BSL). 90-BFR (39.6 ± 12.0 ∆BSL) resulted in a greater StO 2 -Avg compared with HIGH (20.5 ± 13.8 ∆BSL). Also, HIGH (23.68 ± 5.31 ml·kg -1 ·min -1 ) resulted in a greater V̇ o2 compared with 30-BFR (15.43 ± 3.19 ml·kg -1 ·min -1 ), 70-BFR (16.65 ± 3.26 ml·kg -1 ·min -1 ), and 90-BFR (18.28 ± 3.89 ml·kg -1 ·min -1 ); 90-BFR (intervals: 4 = 15.9 ± 2.3; intervals: 5 = 16.4 ± 2.5) resulted in a greater RPE compared with 30-BFR (intervals: 4 = 13.3 ± 1.4; intervals: 5 = 13.7 ± 1.7) during intervals 4 and 5. These results suggest that when adding BFR to various intensities of aerobic exercise, consideration should be given to peak work and VT to provide a balance between high local physiological stress and perceptual responses.

Estimating the Lactate Threshold Using Wireless Near-Infrared Spectroscopy and Threshold Detection Analyses.

The present investigation examined the ability of two threshold detection analyses (maximum distance, Dmax; modified maximum distance, mDmax) in identifying the near-infrared spectroscopy (NIRS) threshold, a lactate threshold (LT) estimate, from exercising tissue oxygen saturation (StO2) responses. Additionally, the test-retest reliability of exercising StO2 and total hemoglobin concentration (THC) responses were examined at moderate and peak cycling intensities. Fourteen healthy, recreationally active participants performed maximal incremental step cycling tests (+25 W / 3 minutes) to volitional fatigue on two separate occasions while StO2 and THC of the vastus lateralis were monitored. Exercising blood [lactate] was collected during Session One. LT and NIRS thresholds (NIRS1, NIRS2) were then determined using Dmax and mDmax threshold analyses. Significant (p < 0.05), moderate correlations were detected between LT and NIRS1 when using Dmax (LT = 130 ± 49 W, NIRS1 = 136 ± 34 W, r = 0.690), but not for mDmax (r = 0.487). No significant test-retest reliability for the NIRS thresholds were observed for Dmax (ICC = 0.351) or mDmax (ICC = 0.385). Exercising StO2 responses demonstrated good reliability (ICC = 0.841-0.873) while exercising THC responses demonstrated moderate-good reliability (ICC = 0.720-0.873) at moderate and peak exercise intensities. The results of this study suggest that neither the Dmax nor mDmax threshold analyses should be used to estimate the LT due to the unreliable detection of the NIRS threshold from session to session.

Comparison of resting metabolic rate prediction equations in college-aged adults.

Prediction equations have been considered an accurate method for estimating resting metabolic rate (RMR) across multiple populations, but their accuracy for college-aged individuals not on an athletics team remains to be determined. Sixty-two college-aged (18-30 yrs) males (n = 31) and females (n = 31) had their RMR measured (RMRm), using indirect calorimetry, and body composition assessed via air-displacement plethysmography. The World Health Organization (WHO), Mifflin-St Jeor (Mifflin), Harris-Benedict (HB), Cunningham, and Nelson equations were used to estimate RMR. No difference was observed between the Cunningham and RMRm regardless of sex (p ≥ 0.05). All other prediction equations estimated a significantly lower RMR for males (p < 0.05). The Mifflin and Nelson equations predicted an RMR that was significantly lower than RMRm for females (p < 0.05). When compared with RMRm, no difference was detected for females using the WHO, HB, or Cunningham (p ≥ 0.05). Only the Nelson equation predicted an RMR that was outside of the clinically acceptable range (±10% of RMRm) regardless of sex. The Cunningham, WHO, and HB equations can accurately predict RMR for college-aged males and females. RMR prediction equations used in this study are less accurate for those with greater RMRs. Novelty: For adults 18-30 years old that are not on an athletics team, the Cunningham equation can accurately predict RMR. The Nelson equation should not be used to predict RMR for this population. There is a systematic bias for RMR prediction equations to underestimate higher measured RMR values.

Muscle blood flow is independent of conduit artery diameter following prior vasodilation in males.

At the onset of exercise in humans, muscle blood flow (MBF) increases to a new steady-state that closely matches the metabolic demand of exercise. This increase has been attributed to "contraction-induced vasodilation," comprised of the skeletal muscle pump and rapid vasodilatory mechanisms. While most research in this area has focused on forearm blood flow (FBF) and vascular conductance, it is possible that separating FBF into diameter and blood velocity can provide more useful information on MBF regulation downstream of the conduit artery. Therefore, we attempted to dissociate the matching of oxygen delivery and oxygen demand by administering glyceryl tri-nitrate (GTN) prior to handgrip exercise. Eight healthy males (29 ± 9 years) performed two trials consisting of two bouts of rhythmic handgrip exercise (30 contractions·min-1 at 5% of maximum) for 6 min, one for each control and GTN (0.4 mg sublingual) condition. Administration of GTN resulted in a 12% increase in resting brachial artery diameter that persisted throughout the duration of exercise (CON: 0.50 ± 0.01 cm; GTN: 0.56 ± 0.01 cm, p < 0.05). Resting FBF was greater following GTN administration compared to control (p < 0.05); however, differences in FBF disappeared following the onset of muscle contractions. Our results indicate that the matching of FBF to oxygen demand during exercise is not affected by prior vasodilation, so that any over-perfusion is corrected at the onset of exercise. Additionally, our findings provide further evidence that the regulation of vascular tone within the microvasculature is independent of the conduit artery diameter.

Effect of Grade and Surface Type on Peak Tibial Acceleration in Trained Distance Runners.

Runners experience repeated impact forces during training, and the culmination of these forces can contribute to overuse injuries. The purpose of this study was to compare peak vertical tibial acceleration (TA) in trained distance runners on 3 surface types (grass, asphalt, and concrete) and 3 grades (incline, decline, and level). During visit 1, subjects completed a 1-mile time trial to determine their pace for all running trials: 80% (5%) of the average time trial velocity. During visit 2, subjects were outfitted with a skin-mounted accelerometer and performed 18 separate running trials during which peak TA was assessed during the stance phase. Each subject ran 2 trials for each condition with 2 minutes of rest between trials. Peak TA was different between decline (8.04 [0.12] g) and incline running (7.31 [0.35] g; P = .020). On the level grade, peak TA was greater during grass (8.22 [1.22] g) compared with concrete (7.47 [1.65] g; P = .017). On the incline grade, grass (7.68 [1.44] g) resulted in higher peak TA than asphalt (6.99 [1.69] g; P = .030). These results suggest that under certain grade conditions grass may result in higher TA compared with either concrete or asphalt.

Acute Neuromuscular and Microvascular Responses to Concentric and Eccentric Exercises With Blood Flow Restriction.

Lauver, JD, Cayot, TE, Rotarius, TR, and Scheuermann, BW. Acute neuromuscular and microvascular responses to concentric and eccentric exercises with blood flow restriction. J Strength Cond Res 34(10): 2725-2733, 2020-The purpose of this study was to investigate the effects of the addition of blood flow restriction (BFR) during concentric and eccentric exercises on muscle excitation and microvascular oxygenation status. Subjects (N = 17) were randomly assigned to either a concentric (CON, CON + BFR) or eccentric (ECC, ECC + BFR) group, with one leg assigned to BFR and the other to non-BFR. Surface electromyography and near-infrared spectroscopy were used to measure muscle excitation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin concentration] during each condition, respectively. On separate days, subjects completed 4 sets (30, 15, 15, 15) of knee extension exercise at 30% maximal torque, and 1 minute of rest was provided between the sets. Greater excitation of the vastus medialis was observed during CON + BFR (54.4 ± 13.3% maximal voluntary isometric contraction [MVIC]) and ECC + BFR (53.0 ± 18.0% MVIC) compared with CON (42.0 ± 10.8% MVIC) and ECC (46.8 ± 9.6% MVIC). Change in deoxy-[Hb + Mb] was greater during CON + BFR (10.0 ± 10.4 µM) than during CON (4.1 ± 4.0 µM; p < 0.001). ECC + BFR (7.8 ± 6.7 µM) was significantly greater than ECC (3.5 ± 4.7 µM; p = 0.001). Total hemoglobin concentration was greater for ECC + BFR (7.9 ± 4.4 µM) compared with ECC (5.5 ± 3.5 µM). The addition of BFR to eccentric and concentric exercises resulted in a significant increase in metabolic stress and muscle excitation compared with non-BFR exercise. These findings suggest that although BFR may increase the hypertrophic stimulus during both modes of contraction, BFR during concentric contractions may result in a greater stimulus.

The Effects of Blood Flow Restriction on Muscle Activation and Hypoxia in Individuals With Chronic Ankle Instability.

CONTEXT: Muscle dysfunction is common in patients with chronic ankle instability (CAI). Blood flow restriction (BFR) may enhance muscle responses during exercise and provide an opportunity to enhance muscle adaptations to ankle rehabilitation exercises; however, there is no evidence examining the effect of BFR on muscle function in CAI patients. OBJECTIVE: Examine the effects of BFR on muscle activation and oxygen saturation during submaximal ankle eversion and dorsiflexion exercises in individuals with CAI. DESIGN: Cross-over study design. SETTING: Laboratory setting. Patients (or Other Participants): Nineteen young adults with a history of CAI. INTERVENTIONS: Participants performed 4 sets (30, 15, 15, and 15) of eversion and dorsiflexion resistance exercises at 30% of maximum voluntary isometric contraction during 2 conditions, BFR and control. For BFR, a cuff was applied above the knee at 80% of blood flow occlusion. For control, the cuff was not inflated. MAIN OUTCOME MEASURES: Fibularis longus and tibialis anterior electromyography muscle activation, lower-leg muscle oxygen saturation, and ratings of perceived exertion were recorded during exercises. RESULTS: Average grand mean muscle activation was 5.6% greater during eversion (P = .03) and 7.7% greater during dorsiflexion (P = .01) resistance exercises with BFR compared with control; however, the magnitudes of the effects of BFR were only clinically important during the dorsiflexion exercises. Lower-leg muscle oxygen saturation was 31% to 44% lower (P < .001) during BFR exercises. Ratings of perceived exertion were significantly higher during BFR exercises (P < .001). CONCLUSIONS: Greater muscle activation and hypoxia were present during submaximal resistance exercise with BFR in participants with CAI. Greater muscle activation and hypoxia during BFR exercises may be important acute responses mediating the training-related muscle adaptations that have been observed with BFR. The presence of these acute responses in CAI patients supports further research examining BFR as a potential ankle rehabilitation tool.

The effect of eccentric exercise with blood flow restriction on neuromuscular activation, microvascular oxygenation, and the repeated bout effect.

PURPOSE: To examine the effect of low-intensity eccentric contractions with and without blood flow restriction (BFR) on microvascular oxygenation, neuromuscular activation, and the repeated bout effect (RBE). METHODS: Participants were randomly assigned to either low-intensity (LI), low-intensity with BFR (LI-BFR), or a control (CON) group. Participants in LI and LI-BFR performed a preconditioning bout of low-intensity eccentric exercise prior to about of maximal eccentric exercise. Participants reported 24, 48, 72, and 96 h later to assess muscle damage and function. Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) were used to measure neuromuscular activation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin] ([THC]) during the preconditioning bout, respectively. RESULTS: During set-2, LI-BFR resulted in greater activation of the VM-RMS (47.7 ± 11.5% MVIC) compared to LI (67.0 ± 20.0% MVIC), as well as during set-3 (p < 0.05). LI-BFR resulted in a greater change in deoxy-[Hb + Mb] compared to LI during set-2 (LI-BFR 13.1 ± 5.2 µM, LI 6.7 ± 7.9 µM), set-3 (LI-BFR 14.6 ± 6 µM, LI 6.9 ± 7.4 µM), and set-4 (p < 0.05). [THC] was higher during LI-BFR compared to LI (p < 0.05). All groups showed a decrease in MVIC torque immediately after maximal exercise (LI 74.2 ± 14.1%, LI-BFR 75 ± 5.1%, CON 53 ± 18.6%). At 24, 48, 72, and 96 h post maximal eccentric exercise, LI and LI-BFR force deficit was not different from baseline. CONCLUSION: This study suggests that the neuromuscular and deoxygenation (i.e., metabolic stress) responses were considerably different between LI and LI-BFR groups; however, these differences did not lead to improvements in the RBE inferred by performing LI and LI-BFR.

The acute effects of bodyweight suspension exercise on muscle activation and muscular fatigue.

This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7 ± 7.4% decline in resistance load throughout the concentric phase (p ≤ 0.05). As a result, BB elicited higher mean resistance loads (31.4 ± 4.0 kg) and biceps brachii sEMG (84.7 ± 27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4 ± 3.4 kg, 63.4 ± 21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (-21.7 ± 7.0 kg) compared with BB (-14.9 ± 4.7 kg); however, BB (-3.0 ± 0.8 kg/set) resulted in a steeper decline in ROF compared with BWS (-1.7 ± 0.6 kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.

Influence of bench angle on upper extremity muscular activation during bench press exercise.

This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free-weight barbell bench press performed at 0°, 30°, 45° and -15° bench angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis displayed no difference during any of the bench conditions when examining the complete concentric contraction, however differences during 26-50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal (98.2 ± 5.4% MVIC) and -15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during -15° (100.4 ± 5.7% MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ± 4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45° resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular activation is affected at various time points when selecting bench press exercises.

Effects of blood flow restriction duration on muscle activation and microvascular oxygenation during low-volume isometric exercise.

The purpose of the investigation was to observe how varying occlusion durations affected neuromuscular activation and microvascular oxygenation during low-volume isometric knee extension exercise. Healthy, recreationally active males performed isometric knee extension at a variety of submaximal intensities under different blood flow restriction (BFR) occlusion durations. The occlusion pressure (130% SBP) was applied either 5 min prior to exercise (PO), immediately prior to exercise (IO) or not during exercise (CON). Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) was used to record the neuromuscular activation and microvascular oxygenation of the knee extensors during exercise. No difference in sEMG was observed in the vastus lateralis or vastus medialis during any exercise condition or any submaximal intensity. PO elicited greater microvascular deoxygenation (deoxy-[Hb + Mb]) compared to CON (P≤0·05) at all submaximal intensities and also compared to IO at 20% maximal voluntary contraction (MVC). IO resulted in a greater deoxy-[Hb + Mb] response during low-intensity exercise (20% and 40% MVC) compared to CON (P≤0·05). These findings suggest that applying BFR 5 min before exercise can enhance the exercise-induced metabolic stress (i.e. deoxy-[Hb + Mb]), measured via NIRS, during low-intensity exercise (20% MVC) compared to applying BFR immediately prior to exercise. Furthermore, the increased metabolic stress observed during IO is attenuated during high-intensity (60% MVC, 80% MVC) exercise when compared to CON conditions. Knowledge of the changes in exercise-induced metabolic stress between the various occlusion durations may assist in developing efficient BFR exercise programmes.