Gilberto C. Laurentino

Strength Training with Blood Flow Restriction Diminishes Myostatin Gene Expression

PURPOSE The aim of the study was to determine whether the similar muscle strength and hypertrophy responses observed after either low-intensity resistance exercise associated with moderate blood flow restriction or high-intensity resistance exercise are associated with similar changes in messenger RNA (mRNA) expression of selected genes involved in myostatin (MSTN) signaling. METHODS Twenty-nine physically active male subjects were divided into three groups: low-intensity (20% one-repetition maximum (1RM)) resistance training (LI) (n = 10), low-intensity resistance exercise associated with moderate blood flow restriction (LIR) (n = 10), and high-intensity (80% 1RM) resistance exercise (HI) (n = 9). All of the groups underwent an 8-wk training program. Maximal dynamic knee extension strength (1RM), quadriceps cross-sectional area (CSA), MSTN, follistatin-like related genes (follistatin (FLST), follistatin-like 3 (FLST-3)), activin IIb, growth and differentiation factor-associated serum protein 1 (GASP-1), and MAD-related protein (SMAD-7) mRNA gene expression were assessed before and after training. RESULTS Knee extension 1RM significantly increased in all groups (LI = 20.7%, LIR = 40.1%, and HI = 36.2%). CSA increased in both the LIR and HI groups (6.3% and 6.1%, respectively). MSTN mRNA expression decreased in the LIR and HI groups (45% and 41%, respectively). There were no significant changes in activin IIb (P > 0.05). FLST and FLST-3 mRNA expression increased in all groups from pre- to posttest (P < 0.001). FLST-3 expression was significantly greater in the HI when compared with the LIR and LI groups at posttest (P = 0.024 and P = 0.018, respectively). GASP-1 and SMAD-7 gene expression significantly increased in both the LIR and HI groups. CONCLUSIONS We concluded that LIR was able to induce gains in 1RM and quadriceps CSA similar to those observed after traditional HI. These responses may be related to the concomitant decrease in MSTN and increase in FLST isoforms, GASP-1, and SMAD-7 mRNA gene expression.

Effects of strength training and vascular occlusion

The purpose of our study was to determine if vascular occlusion produced an additive effect on muscle hypertrophy and strength performance with high strength training loads. Sixteen physically active men were divided into two groups: high-intensity (HI = 6 RM) and moderate-intensity training (MI = 12 RM). An occlusion cuff was attached to the proximal end of the right thigh, so that blood flow was reduced during the exercise. The left leg served as a control, thus was trained without vascular occlusion. Knee extension 1 RM and quadriceps cross-sectional area (MRI) were evaluated pre- and post-8 weeks of training. We only found a main time effect for both strength gains and quadriceps hypertrophy (p < 0.001). Therefore, we conclude that vascular occlusion in combination with high-intensity strength training does not augment muscle strength or hypertrophy when compared to high-intensity strength training alone.

The acute and chronic effects of “NO LOAD” resistance training

The purpose of the study was to remove the influence of an external load and determine if muscle growth can be elicited by maximally contracting through a full range of motion. In addition, the acute physiologic and perceptual responses to each stimulus were also investigated. Thirteen participants completed 18 sessions of unilateral elbow flexion exercise. Each arm was designated to either NO LOAD or HIGH LOAD condition (70% one repetition maximum). For the NO LOAD condition, participants repeatedly contracted as hard as they could through a full range of motion without the use of an external load. Our results show that anterior muscle thickness increased similarly from Pre to Post, with no differences between conditions for the 50% [Pre: 2.7 (0.8) vs. Post: 2.9 (0.7)], 60% [Pre: 2.9 (0.7) vs. Post: 3.1 (0.7)] or 70% [Pre: 3.2 (0.7) vs. Post: 3.5 (0.7)] sites. There was a significant condition×time interaction for one repetition maximum (p=0.017), with HIGH LOAD (+2.3kg) increasing more than the NO LOAD condition (+1kg). These results extend previous studies that have observed muscle growth across a range of external loads and muscle actions and suggest that muscle growth can occur independent of an external load provided there are enough muscle fibers undergoing mechanotransduction.

The Effect of Cuff Width on Muscle Adaptations after Blood Flow Restriction Training.

UNLABELLED Blood flow restriction in combination with low-load resistance training has been shown to increase muscle size and strength; however, the influence of cuff width on these adaptations is unknown. PURPOSE The objective of this study is to determine the influence of different cuff widths on muscle size and strength, and also investigate whether a wider cuff would result in less adaptation compared with a narrow cuff when inflated to the same relative pressure (80% arterial occlusion pressure). METHODS Eleven physically active males had their arms randomly divided into two separate conditions: low-load blood flow restriction exercise with a narrow cuff (BFR + N, 5 cm) and low-load blood flow restriction exercise with a wide cuff (BFR + W, 10 cm). All participants underwent 12 wk of unilateral elbow flexion at 20% of their one-repetition maximum (1RM). The elbow flexion strength (1RM), elbow flexor muscle cross-sectional area (CSA), arterial blood flow, training volume, RPE, and rating of perceived pain were assessed before and after training. RESULTS Elbow flexion 1RM and CSA significantly increased in both conditions (BFR + N = 13.5% and 9% vs BFR + W = 11.9% and 11.2%, respectively). The arterial blood flow was significantly reduced when 80% of the arterial occlusion pressure was applied in both conditions (BFR + N = 61.2% and BFR + W = 63.5%). There were no significant differences in the training volume, RPE, or rating of perceived pain between conditions (P > 0.05). CONCLUSION We wish to suggest that, regardless of cuff width, both protocols produced similar increases in 1RM and elbow flexor muscle CSA, and these responses may be related to the similar training volume and/or similar reductions in arterial blood flow produced when both cuffs were inflated to the same relative pressure.

Efeito da familiarização na estabilização dos valores de 1RM para homens e mulheres

The purpose of this study was to determine the number of familiarization sessions for stabilizing the load of one repetition maximum (1RM) tests on the squat exercise in men and women. Eight men (25 ± 4 years) and eight women (20 ± 1 years) underwent five experimental sessions. ANOVA and Bland-Altman plotting were used to compare the 1RM load between the sessions (p<0.05). The stabilization of load occurred at the fourth session for men and at the third session for women, with significantly increased in relative and absolute strength from the first to the fourth (17kg and 19%) and from the first to the third (9kg and 14%) session, respectively. However, relative strength did not differ significantly between genders. According to our results, individuals not experienced with strength training can reach high reliability in the 1RM test in the squat exercise, after performing three or four familiarizations sessions.

The effects of upper body exercise across different levels of blood flow restriction on arterial occlusion pressure and perceptual responses.

Recent studies have investigated relative pressures that are applied during blood flow restriction exercise ranging from 40%-90% of resting arterial occlusion pressure; however, no studies have investigated relative pressures below 40% arterial occlusion pressure. The purpose of this study was to characterize the cardiovascular and perceptual responses to different levels of pressures. Twenty-six resistance trained participants performed four sets of unilateral elbow flexion exercise using 30% of their 1RM in combination with blood flow restriction inflated to one of six relative applied pressures (0%, 10%, 20%, 30%, 50%, 90% arterial occlusion pressure). Arterial occlusion pressure was measured before (pre) and immediately after the last set of exercise at the radial artery. RPE and discomfort were taken prior to (pre) and following each set of exercise. Data presented as mean (95% CI) except for perceptual responses represented as the median (25th, 75th percentile). Arterial occlusion pressure increased from pre to post (p<0.001) in all conditions but was augmented further with higher pressures [e.g. 0%: 36 (30-42) mmHg vs. 10%: 39 (34-44) mmHg vs. 90% 46 (41-52) mmHg]. For RPE and discomfort, there were significant differences across conditions for all sets of exercise (p<0.01) with the ratings of RPE [e.g. 0%: 14.5 (13, 17) vs. 10%: 13.5 (12, 17) vs. 90%: 17 (14.75, 19) during last set] and discomfort [e.g. 0%: 3.5 (1.5, 6.25) vs. 10%: 3 (1, 6) vs. 90%: 7 (4.5, 9) during last set] generally being greater at the higher restriction pressures. All of these differences at the higher restriction pressures occurred despite completing a lower total volume of exercise. Applying higher relative pressures results in the greatest cardiovascular response, higher perceptual ratings, and greater decrease in exercise volume compared to lower restriction pressures. Therefore, the perceptual responses from lower relative pressures may be more appealing and provide a safer and more tolerable stimulus for individuals.

Can blood flow restriction augment muscle activation during high‐load training?

Blood flow restriction has been shown to augment muscle activation and increase muscle size when combined with low‐load training; however, much less is known on whether blood flow restriction can augment muscle activation during high‐load exercise.

The influence of time on determining blood flow restriction pressure

The influence of time, manifested in the oscillatory nature of physiology, has been documented in many processes. Within blood flow restriction literature, the restrictive stimulus is often applied based on a single arterial occlusion measurement, which is closely related to brachial systolic blood pressure (bSBP). Considering the oscillatory nature of bSBP, it is likely that time also influences arterial occlusion measurements. OBJECTIVES To investigate the influence of time, within and between days, on arterial occlusion pressure and to determine whether the variability resembles the oscillatory pattern of bSBP. DESIGN Test-retest. METHODS Twenty-two participants completed four testing sessions at 08:00 and 18:00h, 48h apart. Arm circumference, bSBP, and brachial diastolic blood pressure (bDBP) were measured at rest. Arterial occlusion pressure was determined using a cuff inflated on the proximal portion of the upper arm, with a Doppler probe placed over the radial artery. RESULTS Significant differences [mean (SD)] were observed for arterial occlusion pressure between Morning Day 2 [132 (14) mmHg, p<0.05], and all other visits [Morning Day 1: 138 (16); Evening Day 1: 139 (17); Evening Day 2 138 (14) mmHg]. A time effect was observed for bSBP, with a post-hoc test revealing that Morning Day 2 was different from all other visits. CONCLUSIONS Our findings suggest that arterial occlusion pressure is influenced by the time of day. As such, multiple occlusion measurements across an experiment may be necessary in order to account for potential oscillations in pressure and provide the intended relative restrictive stimulus.

Effects of different strength training frequencies during reduced training period on strength and muscle cross-sectional area

Abstract This study investigated the effects of different reduced strength training (RST) frequencies on half-squat 1 RM and quadriceps cross-sectional area (QCSA). Thirty-three untrained males (24.7 ± 3.9 years; 1.73 ± 0.08 m; 74.6 ± 8.4 kg) underwent a 16-week experimental period (i.e. eight weeks of strength training [ST] followed by additional eight weeks of RST). During the ST period, the participants performed 3–4 sets of 6–12 RM, three sessions/week in half-squat and knee extension exercises. Following ST, the participants were randomly allocated to one of three groups: reduced strength training with one (RST1) or two sessions per week (RST2), and ceased training (CT). Both RST1 and RST2 groups had their training frequency and total training volume-load (i.e. RST1 = 50.3% and RST2 = 57.1%) reduced, while the CT group stopped training completely. Half-squat 1 RM (RST1 = 27.9%; RST2 = 26.7%; and CT = 28.4%) and QCSA (RST1 = 6.1%; RST2 = 6.9%; and CT = 5.8%) increased significantly (p < .05) in all groups after eight weeks of ST. No significant changes were observed in 1 RM and QCSA for RST1 and RST2 groups after the RST period, while the CT group demonstrated a decrease in half-squat 1 RM (22.6%) and QCSA (5.4%) when compared to the ST period (p < .05). In conclusion, different RST frequencies applied were able to maintain muscle mass and strength performance obtained over the regular ST period. Thus, it appears that RST frequency does not affect the maintenance of muscle mass and strength in untrained males, as long as volume-load is equated between frequencies.

The acute muscular response to blood flow‐restricted exercise with very low relative pressure

To investigate the acute responses to blood flow‐restricted (BFR) exercise across low, moderate and high relative pressures. Muscle thickness, maximal voluntary contraction (MVC) and electromyography (EMG) amplitude were assessed following exercise with six different BFR pressures: 0%, 10%, 20%, 30%, 50% and 90% of arterial occlusion pressure (AOP). There were differences between each time point within each condition for muscle thickness, which increased postexercise [+0·47 (0·40, 0·54) cm] and then trended towards baseline. For MVC, higher pressures resulted in greater decrements than lower pressures [e.g. 10% AOP: −20·7 (−15·5, −25·8) Nm versus 90% AOP: −24 (−19·1, −28·9) Nm] postexercise. EMG amplitude increased from the first three repetitions to the last three repetitions within each set. When using a common BFR protocol with 30% 1RM, applying BFR does not seem to augment acute responses over that of exercise alone when exercise is taken to failure.