The Effect Of Eccentric Exercise With Blood Flow Restriction On Muscle Damage Neuromuscular Activation And Microvascular Oxygenation

Author : Jakob Del Lauver
Publisher :
ISBN 13 :
Total Pages : 185 pages
Book Rating : 4.:/5 (953 download)

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Download or read book The Effect of Eccentric Exercise with Blood Flow Restriction on Muscle Damage, Neuromuscular Activation, and Microvascular Oxygenation written by Jakob Del Lauver and published by . This book was released on 2015 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite the fact that numerous previous investigations have demonstrated the robust effects of BFR resistance training in producing muscle hypertrophy and improved strength, the underlying mechanisms responsible for such effects remain poorly understood. Limited work has been done examining the effects of contraction type on the acute responses to BFR resistance training. In addition, while BFR has been demonstrated to induce similar improvement in muscle mass and strength, it is unknown what effect it will have on the muscles response when subsequent high-intensity exercise is performed. Purpose: The purpose of this dissertation was to examine the effect that eccentric muscle actions with BFR have on microvascular oxygenation and neuromuscular activation, as well as to examine the effects that eccentric actions with BFR has on attenuating muscle damage during a subsequent bout of maximal exercise. Methods: Participants where healthy, recreationally active and/or sedentary college aged males. Participants were randomly assigned to one of three groups, 30% of maximal torque (LOW), 30% of maximal torque with BFR (LBFR), or control (CON). Participants in both LOW and LBFR groups performed a precondition bout of low-intensity eccentric exercise consisting of four sets (1x30, 3x15) of eccentric exercise of the knee extensors (quadriceps). The LBFR performed the exercise bout with the addition of BFR, with an external occlusion pressure corresponded to 130% of the resting systolic blood pressure. Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) was used to record the neuromuscular activation and microvascular oxygenation of the knee extensors during the low-intensity precondition exercise (LOW, LBFR). Ninety-six hours after the precondition exercise, all participants performed a bout of maximal eccentric exercise consisting of six sets of ten repetitions, this was done in an attempt to induce muscle damage. Following the maximal eccentric exercise bout, all participants reported back 24, 48, 72, and 96 hours later to assess muscle damage and function. Muscle damage and function was assessed via changes in maximal voluntary isometric contraction (MVIC) torque, maximal voluntary concentric torque, range of motion (ROM), muscle soreness, and mid-thigh circumference. Results: There was a significant difference in neuromuscular activation of the vastus medialis (VM-RMS-root mean squared) between LOW and LBFR (p = 0.05). During set-2 LBFR resulted in greater activation of the VM-RMS (LOW 47.7 ± 11.5% MVIC, LBFR 67.0 ± 20.0% MVIC) compared to LOW, as well as during set-3 (LOW 51.4 ± 8.6% MVIC, LBFR 69.53 ± 20.5% MVIC). There was a significant difference in deoxyhemoglobin signal (deoxy-[Hb+Mb]) between LBFR and LOW during set-2 (LBFR 13.1 ± 5.2 μM, LOW 6.7 ± 7.9 μM), set-3 (LBFR 14.6 ± 6 μM, LOW 6.9 ± 7.4 μM), and set-4 (LBFR 13.8 ± 5.9 μM, LOW 7.8 ± 8.5 μM). Total hemoglobin concentration [THC] was significantly higher during LBFR compared to LOW (p = 0.03). Immediately post maximal eccentric exercise all groups showed a significant decrease in MVIC torque (LOW 74.2 ± 14.1%, LBFR 75 ± 5.1%, CON 53 ± 18.6%), with LOW and LBFR resulted in a smaller decrease compared to CON. At 24, 48, 72, and 96 hours post maximal eccentric exercise both LOW and LBFR did not demonstrate a significant force deficit from baseline. Conclusion: The results of the current investigations suggest that the LBFR condition resulted in increased metabolic stress, as shown by the greater deoxy-[Hb+Mb] response and increased blood volume (increased [THC]), as well as greater neuromuscular activation compared to LOW. In spite of the considerable differences observed in the preconditioning exercise stimulus, there was no difference observed in the protective effect inferred by LOW and LBFR preconditioning. However, both LOW and LBFR resulted in a significant protective effect. Further studies are necessary to determine the mechanisms responsible for the protective effect conferred by both low-intensity and low-intensity with BFR eccentric actions against maximal eccentric actions induced muscle damage.