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Effects Of Blood Flow Restriction And Neuromuscular Electrical Stimulation On Strength Of The Plantar Flexors

2020; Lippincott Williams & Wilkins; Volume: 52; Issue: 7S Linguagem: Inglês

10.1249/01.mss.0000685068.07154.29

1530-0315

Jonathan A. Aguilera, Yaremi M. Ontiveros, John Poli, Joshua A. Cotter,

Heart Rate Variability and Autonomic Control

Exposure to a microgravity environment removes the frequent loading of postural, or antigravity muscles, such as those found in the calf. Due to this reduced stimulation, muscle mass and strength are greatly reduced. Blood flow restriction (BFR) and neuromuscular electrical stimulation (NMES) are unconventional training methods that have been shown to elicit growth in thigh and wrist musculature. However, the effects of these methods on the calves are unknown. PURPOSE: The purpose of this study was to explore the effectiveness of BFR and NMES individually and in combination for increasing calf strength. METHODS: Thirteen participants (9 males and 4 females; 20.15 ± 1.72 yr, 69.95 ± 11.45 kg) were recruited from California State University, Long Beach with each leg being randomized to one of three training conditions: 1) BFR only, 2) NMES only, or 3) BFR and NMES, for six weeks of training. Calf strength was measured using an isokinetic dynamometer to assess peak and average torque during maximal plantar flexion contractions through a range of velocities (0-210 deg/s). Comparisons were made using separate two-way ANOVA's for each variable. RESULTS: Average isometric torque during five second maximal plantar flexion contractions increased in the NMES (P=0.019) and BFRNMES groups (P=0.01), while peak isometric torque only increased in the NMES group (P=0.031). Peak torque at 30 deg/sec and 90 deg/sec increased only with BFRNMES (P=0.001 and P=0.008, respectively). A significant main effect for time was found at 60 deg/sec (P=0.014) and 210 deg/sec (P=0.019), with no differences found during post-hoc comparisons. No significant differences were found at the other velocities. CONCLUSION: NMES and BFRNMES conditions may have potential for increasing strength of the plantar flexors at slower velocities (≤90 deg/sec). This study adds to the literature regarding the feasibility of these methods as alternative exercise countermeasures for promoting favorable adaptations in the calf musculature. This research was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Numbers; UL1GM118979; TL4GM118980; RL5GM118978.