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- Title
Acute physiological responses to combined blood flow restriction and low-level laser.
- Authors
Chen, Yi-Ching; Su, Yu-Han; Lin, Yen-Ting; Huang, Chien-Chun; Hwang, Ing-Shiou
- Abstract
<bold>Purpose: </bold>Blood flow restriction (BFR) is an innovation in fitness to train muscles with low loads at low oxygen levels. Low-level laser therapy (LLLT) is a bio-energetic approach to alleviate muscle fatigue during resistance training. This study investigated the immediate effect of LLLT pre-conditioning on BFR that accelerates muscle fatigue due to ischemia.<bold>Methods: </bold>Fifteen young adults participated in this study of a crossover randomized design. They completed a low-load contraction with various pre-conditioning (blood flow restriction with low-level laser therapy (LLLT + BFR), blood flow restriction with sham low-level laser therapy (BFR), and control). Force fluctuation dynamics, muscle oxygen saturation of hemoglobin and myoglobin (SmO2), and discharge patterns of motor units (MU) were compared.<bold>Results: </bold>Normalized SmO2 during low-load contractions significantly varied with the pre-contraction protocols (Control (83.6 ± 3.0%) > LLLT + BFR (70.3 ± 2.8%) > BFR (55.4 ± 2.4%). Also, force fluctuations and MU discharge varied with the pre-contraction protocols. Multi-scale entropy and mean frequency of force fluctuations were greater in the LLLT + BFR condition (31.95 ± 0.67) than in the BFR condition (29.47 ± 0.73). The mean inter-spike interval of MUs was greater in the LLLT + BFR condition (53.32 ± 2.70 ms) than in the BFR condition (45.04 ± 1.08 ms). In particular, MUs with higher recruitment thresholds exhibited greater LLLT-related discharge complexity (LLLT + BFR (0.201 ± 0.012) > BFR (0.154 ± 0.006)).<bold>Conclusions: </bold>LLLT pre-conditioning can minimize the BFR-related decline in muscle oxygen saturation, leading to force gradation and MU discharge in a cost-effective and complex manner.
- Subjects
BLOOD flow; MUSCLE fatigue; MOTOR unit; LASERS; RESISTANCE training; SKELETAL muscle physiology; MUSCLE contraction; SKELETAL muscle; BLOOD circulation; RESEARCH funding; ELECTROMYOGRAPHY; HEMODYNAMICS
- Publication
European Journal of Applied Physiology, 2020, Vol 120, Issue 6, p1437
- ISSN
1439-6319
- Publication type
journal article
- DOI
10.1007/s00421-020-04378-6