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We aimed to compare individual hypertrophic responses to high-load resistance training (HL-RT) or high-load with blood flow restriction (HL-BFR). Furthermore, we investigated whether greater responsiveness to one of the protocols could be explained by acute changes in blood deoxyhemoglobin concentration (HHb) and total hemoglobin concentration (tHb) (proxy markers of metabolic stress). Ten untrained participants had their legs randomized into both HL-RT and HL-BFR and underwent 10 weeks of training. Muscle cross-sectional area (mCSA) was measured at baseline and post training, while HHb and tHb during the final session. Using a threshold of 2 × typical errors (3.24%) to compare protocols, five participants showed greater mCSA increases after HL-RT (16.44 ± 7.90%) compared to HL-BFR (10.74 ± 7.12%, p = 0.0054) and five did not respond better to HL-RT (8.95 ± 10.83%) compared to HL-BFR (13.33 ± 8.59%) (p = 0.3105). Additionally, HL-RT induced lower HHb (5855.78 ± 12905.99; p = 0.0101) and tHb (−43169.70 ± 37793.17; p = 0.0030) AUC values compared to HL-BFR (HHb: 39254.80 ± 27020.15; tHb: 46309.40 ± 31613.97). In conclusion, despite the higher levels of metabolic stress markers, most participants did not present greater muscle hypertrophy by combining blood flow restriction with HL-RT. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the effects of progressive overload in resistance training on muscle strength and cross-sectional area (CSA) by specifically comparing the impact of increasing load (LOADprog) versus an increase in repetitions (REPSprog). We used a within-subject experimental design in which 39 previously untrained young persons (20 men and 19 women) had their legs randomized to LOADprog and REPSprog. Outcomes were assessed before and after 10 weeks of training. Muscle strength was assessed using the one repetition maximum (1RM) test on the leg extension exercise, and the CSA of the vastus lateralis was assessed by ultrasonography. Both protocols increased 1RM values from pre (LOADprog: 52.90±16.32 kg; REPSprog: 51.67±15.84 kg) to post (LOADprog: 69.05±18.55 kg, REPSprog: 66.82±17.95 kg), with no difference between them (P +>+0.05). Similarly, both protocols also increased in CSA values from pre (LOADprog: 21.34±4.71 cm²; REPSprog: 21.08±4.62 cm²) to post (LOADprog: 23.53±5.41 cm², REPSprog: 23.39±5.19 cm²), with no difference between them (P +>+0.05). In conclusion, our findings indicate that the progression of overload through load or repetitions can be used to promote gains in strength and muscle hypertrophy in young men and women in the early stages of training. [ABSTRACT FROM AUTHOR]

Bergamasco, JGA, Gomes da Silva, D, Bittencourt, DF, Martins de Oliveira, R, Júnior, JCB, Caruso, FC, Godoi, D, Borghi-Silva, A, and Libardi, CA. Low-load resistance training performed to muscle failure or near muscle failure does not promote additional gains on muscle strength, hypertrophy, and functional performance of older adults. J Strength Cond Res 36(5): 1209–1215, 2022—The aim of the present study was to compare the effects of low-load resistance training (RT) protocols performed to failure (FAI), to voluntary interruption (VOL), and with a fixed low repetitions (FIX) on muscle strength, hypertrophy, and functional performance in older adults. Forty-one subjects (60–77 years) were randomized into one of the RT protocols (FAI, VOL, or FIX) and completed 12 weeks of RT at 40% of 1 repetition maximum (1RM), twice a week. The assessments included 1RM test, muscle cross-sectional area (CSA), rate of torque development (RTD), and functional performance (chair stand [CS], habitual gait speed [HGS], maximal gait speed [MGS], and timed up-and-go [TUG]). All protocols significantly increased 1RM values from Pre (FAI: 318.3 ± 116.3 kg; VOL: 342.9 ± 93.7 kg; FIX: 328.0 ± 107.2 kg) to Post (FAI: 393.0 ± 143.1 kg, 23.5%; VOL: 423.0 ± 114.5 kg, 23.3%; FIX: 397.8 ± 94.6 kg, 21.3%; p < 0.0001 for all groups). Regarding CS, all protocols showed significant improvements from Pre (FAI: 11.5 ± 2.4 seconds; VOL: 12.1 ± 2.5 seconds; FIX: 11.3 ± 1.1 seconds) to Post (FAI: 10.5 ± 1.1 seconds, −8.5%, p = 0.001; VOL: 10.3 ± 1.5 seconds, −15.1%, p = 0.001; FIX: 11.0 ± 1.1, −3.2%, p = 0.001). Habitual gait speed values increased significantly from Pre (FAI: 1.3 ± 0.2 m·s−1; VOL: 1.3 ± 0.1 m·s−1; FIX: 1.3 ± 0.1 m·s−1) to Post (FAI: 1.4 ± 0.2 m·s−1, 2.5%, p = 0.03; VOL: 1.4 ± 0.2 m·s−1, 5.2%, p = 0.036; FIX: 1.4 ± 0.1 m·s−1, 5.7%, p = 0.03). No significant differences between protocols were found (p > 0.05). In addition, there were no significant changes in CSA, RTD, MGS, and TUG for any protocols (p > 0.05). In conclusion, low-load RT performed without muscle failure promotes significant improvements in muscle strength and some parameters of functional performance in older adults. [ABSTRACT FROM AUTHOR]

Purpose: Manual reconstruction (MR) of the vastus lateralis (VL) muscle cross-sectional area (CSA) from sequential ultrasound (US) images is accessible, is reproducible, and has concurrent validity with magnetic resonance imaging. However, this technique requires numerous controls and procedures during image acquisition and reconstruction, making it laborious and time-consuming. The aim of this study was to determine the concurrent validity of VL CSA assessments between MR and computer vision-based automated reconstruction (AR) of CSA from sequential images of the VL obtained by US., Methods: The images from each sequence were manually rotated to align the fascia between images and thus visualize the VL CSA. For the AR, an artificial neural network model was utilized to segment areas of interest in the image, such as skin, fascia, deep aponeurosis, and femur. This segmentation was crucial to impose necessary constraints for the main assembly phase. At this stage, an image registration application, combined with differential evolution, was employed to achieve appropriate adjustments between the images. Next, the VL CSA obtained from the MR ( n = 488) and AR ( n = 488) techniques was used to determine their concurrent validity., Results: Our findings demonstrated a low coefficient of variation (CV) (1.51%) for AR compared with MR. The Bland-Altman plot showed low bias and close limits of agreement (+1.18 cm 2 , -1.19 cm 2 ), containing more than 95% of the data points., Conclusions: The AR technique is valid compared with MR when measuring VL CSA in a heterogeneous sample., (Copyright © 2024 by the American College of Sports Medicine.)

Context: Low-load resistance training (LL) and neuromuscular electrostimulation (NES), both combined with blood flow restriction (BFR), emerge as effective strategies to maintain or increase muscle mass. It is well established that LL-BFR promotes similar increases in muscle cross-sectional area (CSA) and lower rating of perceived exertion (RPE) and pain compared with traditional resistance training protocols. On the other hand, only 2 studies with conflicting results have investigated the effects of NES-BFR on CSA, RPE, and pain. In addition, no study directly compared LL-BFR and NES-BFR., Objective: The aim of the study was to compare the effects of LL-BFR and NES-BFR on vastus lateralis CSA, RPE, and pain. Individual response for muscle hypertrophy was also compared between protocols., Design: Intrasubject longitudinal study., Setting: University research laboratory., Intervention: Fifteen healthy young males (age = 23 [5] y; weight = 77.6 [11.3] kg; height = 1.76 [0.08] m)., Main Outcome Measures: Vastus lateralis CSA was measured through ultrasound at baseline (pre) and after 20 training sessions (post). The RPE and pain responses were obtained through modified 10-point scales, handled during all training sessions., Results: Both protocols demonstrated significant increases in muscle CSA (P < .0001). However, the LL-BFR demonstrated significantly greater CSA changes compared with NES-BFR (LL-BFR = 11.2%, NES-BFR = 4.6%; P < .0001). Comparing individual increases in CSA, 12 subjects (85.7% of the sample) presented greater muscle hypertrophy for LL-BFR than for the NES-BFR protocol. In addition, LL-BFR produced significantly lower RPE and pain responses (P < .0001)., Conclusions: The LL-BFR produced significantly greater increases in CSA with significant less RPE and pain than NES-BFR. In addition, LL-BFR resulted in greater individual muscle hypertrophy responses for most subjects compared with NES-BFR.