Sequential use of low-load-blood-flow-restricted vs. high-load resistance training on neuromuscular activation, hypertrophy and neuromuscular performance

Abstract

Introduction Low-load Blood Flow Restriction training (BFRT) is a viable alternative to high-load resistance training (HLT), especially for clinical populations, due to its lower mechanical tension (Centner et al., 2019). Despite using lower loads, BFRT achieves comparable or slightly lower gains in muscle hypertrophy and strength than HLT. However, neural adaptations after low-load BFRT remain poorly understood and are hypothesized to be less pronounced (Centner & Lauber, 2020). Thus, this study aimed to compare the effects of BFRT and HLT, as well as the sequential application of HLT following BFRT, to address potential gaps in neuromuscular adaptation (Duchateau et al., 2021). Methods In this 10-week randomized controlled trial, 37 healthy male and female adults (35-60 years) completed progressive resistance training for knee extensors either 8 weeks with low-load BFRT followed by 2 weeks of HLT, or exclusively HLT. Measurements at baseline including familiarization (PRE1 and PRE2), 8 weeks (MID) and 10 weeks (POST) included maximal voluntary contraction of knee extensors (MVC), leg press strength (LP), voluntary activation (VA, via electrical muscle stimulation) and vastus lateralis muscle volume (V_VL, via ultrasound at 30-70% femur length). Linear mixed models were used to analyze group differences over time, with Cohen’s d effect sizes. Here, we report the preliminary data of 20 participants. Results Reliability between PRE1 and PRE2 was excellent for MVC and V_VL (ICC>0.98) and good for LP (ICC=0.88). From PRE2 to POST, MVC showed a moderate overall increase (+14.7%, d=0.49), while from MID to POST the BFRT group benefited slightly more (d=-0.14). LP increased similarly in both groups at MID (+5.9), but at POST, the HLT group demonstrated a greater increase compared to the BFRT group (+14.8%, d=0.32). No meaningful differences in VA changes were observed between groups or across timepoint, however, the interaction at POST favored more change in BFRT compared to HLT (d=-0.3). Both groups showed comparable increases in V_VL, with negligible differences between groups (+3.4%, d=0.05). Discussion/Conclusion The results of the analyzed sub-sample imply that BFRT and HLT lead to similar changes in maximal force, neural adaptation, and muscle size, however, a large variability was found. The greater increase in VA and MVC in the BFRT group at POST suggests that sequential HLT training after BFRT may enhance performance more than HLT alone (Duchateau et al., 2021). The analysis of the remaining participants may help clarify these effects and enlighten, how mechanical tension and metabolic stress contribute to neural adaptations. References Centner, C., & Lauber, B. (2020). A systematic review and meta-analysis on neural adaptations following blood flow restriction training: What we know and what we don’t know. Frontiers in Physiology, 11, Article 887. https://doi.org/10.3389/fphys.2020.00887 Centner, C., Wiegel, P., Gollhofer, A., & König, D. (2019). Effects of blood flow restriction training on muscular strength and hypertrophy in older individuals: A systematic review and meta-analysis. Sports Medicine, 49(1), 95–108. https://doi.org/10.1007/s40279-018-0994-1 Duchateau, J., Stragier, S., Baudry, S., & Carpentier, A. (2021). Strength training: In search of optimal strategies to maximize neuromuscular performance. Exercise and Sport Sciences Reviews, 49(1), 2. https://doi.org/10.1249/JES.0000000000000234

Keywords

• strength
• blood-flow restriction training
• high-load training
• voluntary activation
• hypertrophy