Strength Training with Blood Flow Restriction Diminishe Myostatin Gene Expression
The aim of the study was to determine whether the similar muscle strength and hypertrophy responses observed after either low-intensity resistanceexercise associated with moderate blood-flow restriction or high-intensity resistance exercise are associated with similar changes in mRNA expression of selected genes involved in the myostatin (MSTN) signaling.
Twenty-nine physically active male subjects were divided into three groups: low-intensity (20% 1-RM) resistance training: LI (n = 10); low-intensity (20% 1-RM) resistance training associated with moderate blood-flow restriction: LIR (n = 10); and high-intensity (80% 1-RM) resistance training: HI (n = 9). All of the groups underwent an 8-week training program. Maximal dynamic knee-extension strength (1-RM), quadriceps cross-sectional area (CSA), MSTN, follistatin-like related genes (FLST, 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 pre- and post-training.
Knee extension 1-RM significantly increased in all groups (LI: 20.7%, LIR: 40.1%, and HI: 36.2%). CSA increased in both 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 post-test (p<0.001). FLST-3 expression was significantly greater in the HI when compared to LIR and LI groups at post-test (p=0.024 and p=0.018, respectively). GASP-1 and SMAD-7 gene expression significantly increased in both LIR and HI groups.
We concluded that LIR was able to induce similar gains in 1-RM and quadriceps CSA than 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
Combined effects of low-intensity blood flow restriction training and high-intensity resistance trainingon muscle strength and size.
We investigated the combined effect of low-intensity blood flow restriction and high-intensity resistance training on muscle adaptation. Forty young men (aged 22-32 years) were randomly divided into four groups of ten subjects each: high-intensity resistance training (HI-RT, 75% of one repetition maximum [1-RM]), low-intensity resistance training with blood flow restriction (LI-BFR, 30% 1-RM), combined HI-RT and LI-BFR (CB-RT, twice-weekly LI-BFR and once-weekly HI-RT), and nontraining control (CON). Three training groups performed bench press exercises 3 days/week for 6 weeks. During LI-BFR training sessions, subjects wore pressure cuffs on both arms that were inflated to 100-160 mmHg. Increases in 1-RM were similar in the HI-RT (19.9%) and CB-RT (15.3%) groups and lower in the LI-BFR group (8.7%, p < 0.05). Maximal isometric elbow extension (MVC) increased in the HI-RT (11.3%) and CB-RT (6.6%) groups; there was no change in the LI-BFR group (-0.2%). The cross-sectional area (CSA) of the triceps brachii (TB) increased (p < 0.05) in the HI-RT (8.6%), CB-RT (7.2%), and LI-BFR (4.4%) groups. The change in relative isometric strength (MVC divided by TB CSA) was greater (p < 0.05) in the HI-RT group (3.3%) than in the LI-BFR (-3.5%) and CON (-0.1%) groups. Following training, relative dynamic strength (1-RM divided by TB CSA) was increased (p < 0.05) by 10.5% in the HI-RT group and 6.7% in the CB-RT group. None of the variables in the CON group changed. Our results show that low-intensity resistance training with BFR-induced functional muscle adaptations is improved by combining it with HI-RT.