The effect of eccentric exercise with blood flow restriction on neuromuscular activation, microvascular oxygenation, and the repeated bout effect.
OBJECTIVE
To examine the effect of low-intensity eccentric contractions with and without blood flow restriction (BFR) on microvascular oxygenation, neuromuscular activation, and the repeated bout effect (RBE).


METHODS
Participants were randomly assigned to either low-intensity (LI), low-intensity with BFR (LI-BFR), or a control (CON) group. Participants in LI and LI-BFR performed a preconditioning bout of low-intensity eccentric exercise prior to about of maximal eccentric exercise. Participants reported 24, 48, 72, and 96 h later to assess muscle damage and function. Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) were used to measure neuromuscular activation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin] ([THC]) during the preconditioning bout, respectively.


RESULTS
During set-2, LI-BFR resulted in greater activation of the VM-RMS (47.7 ± 11.5% MVIC) compared to LI (67.0 ± 20.0% MVIC), as well as during set-3 (p < 0.05). LI-BFR resulted in a greater change in deoxy-[Hb + Mb] compared to LI during set-2 (LI-BFR 13.1 ± 5.2 µM, LI 6.7 ± 7.9 µM), set-3 (LI-BFR 14.6 ± 6 µM, LI 6.9 ± 7.4 µM), and set-4 (p < 0.05). [THC] was higher during LI-BFR compared to LI (p < 0.05). All groups showed a decrease in MVIC torque immediately after maximal exercise (LI 74.2 ± 14.1%, LI-BFR 75 ± 5.1%, CON 53 ± 18.6%). At 24, 48, 72, and 96 h post maximal eccentric exercise, LI and LI-BFR force deficit was not different from baseline.


CONCLUSIONS
This study suggests that the neuromuscular and deoxygenation (i.e., metabolic stress) responses were considerably different between LI and LI-BFR groups; however, these differences did not lead to improvements in the RBE inferred by performing LI and LI-BFR.
Department of Exercise and Rehabilitative Sciences, University of Toledo, 2801 West Bancroft Street, Toledo, OH, 43606, USA. jlauver@adrian.edu.|Department of Exercise Science and Athletic Training, Adrian College, 110 South Madison Street, Adrian, MI, 49221, USA. jlauver@adrian.edu.
Jakob D
JD
Lauver
Department of Exercise and Rehabilitative Sciences, University of Toledo, 2801 West Bancroft Street, Toledo, OH, 43606, USA.|Division of Mathematics, Computer and Natural Sciences, Ohio Dominican University, 1216 Sunbury Road, Columbus, OH, 43219, USA.
Trent E
TE
Cayot
Department of Exercise and Rehabilitative Sciences, University of Toledo, 2801 West Bancroft Street, Toledo, OH, 43606, USA.
Timothy
T
Rotarius
Department of Exercise and Rehabilitative Sciences, University of Toledo, 2801 West Bancroft Street, Toledo, OH, 43606, USA.
Barry W
BW
Scheuermann
D000328:Adult; D015444:Exercise; D006801:Humans; D019194:Ischemic Preconditioning / Q000009:adverse effects / Q000379:methods*; D008297:Male; D055806:Microvessels / Q000502:physiology; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D063806:Myalgia / Q000517:prevention & control*; D010101:Oxygen Consumption; D012039:Regional Blood Flow
Blood flow restriction; Near-infrared spectroscopy; Repeated bout effect