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- Huseth, Kari, et al.
(författare)
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Assessment of neuromuscular activity during maximal isometric contraction in supine vs standing body positions
- 2020
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Ingår i: Journal of Electromyography and Kinesiology. - : Elsevier BV. - 1050-6411. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- Background: When comparing neuromuscular activity between different individuals or different conditions by use of surface electromyography (sEMG) it is necessary to apply standardized assessment protocol. Most frequently used method is the maximum voluntary isometric contraction (MVIC). However, the influence of body posture on sEMG activity during MVIC testing remains largely unknown. Aim: To evaluate the MVIC method for sEMG normalization in supine versus standing positions for selected muscles of the lower extremity and trunk. Methods: Twelve healthy individuals participated; five females and seven males (age 22–51 yrs). sEMG signals were recorded bilaterally from mm tibialis anterior, gluteus medius, adductor longus, rectus abdominus, external oblique and internal oblique/transversus abdominus according to standardized test protocol. Two different body positions were used: supine and standing position. Results: MVIC peak sEMG signal amplitudes did not differ systematically between supine and standing test positions. Pronounced inter-subject variability in MVIC reference sEMG activity were observed between participants, during both supine and standing test positions. Conclusion: Present data demonstrate that MVIC EMG normalization is a biomechanically stable procedure that can be performed in a reproducible manner for the major leg and trunk muscles when comparing supine vs. standing test positions. © 2019 Elsevier Ltd
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- Vissing, K., et al.
(författare)
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Myocellular Adaptations to Low-Load Blood Flow Restricted Resistance Training
- 2020
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Ingår i: Exercise and sport sciences reviews. - : Ovid Technologies (Wolters Kluwer Health). - 0091-6331 .- 1538-3008. ; 48:4, s. 180-187
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Tidskriftsartikel (refereegranskat)abstract
- Low-load blood flow restricted resistance exercise (BFRRE) can stimulate whole-muscle growth and improve muscle function. However, limited knowledge exists on the effects at the myocellular level. We hypothesize that BFRRE has the ability to produce concurrent skeletal muscle myofibrillar, mitochondrial, and microvascular adaptations, thus offering an alternative strategy to counteract decay in skeletal muscle health and function in clinical populations.
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- Wernbom, Mathias, 1968, et al.
(författare)
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Muscle fibre activation and fatigue with low-load blood flow restricted resistance exercise—An integrative physiology review
- 2020
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 228:1
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Forskningsöversikt (refereegranskat)abstract
- Blood flow-restricted resistance exercise (BFRRE) has been shown to induce increases in muscle size and strength, and continues to generate interest from both clinical and basic research points of view. The low loads employed, typically 20%-50% of the one repetition maximum, make BFRRE an attractive training modality for individuals who may not tolerate high musculoskeletal forces (eg, selected clinical patient groups such as frail old adults and patients recovering from sports injury) and/or for highly trained athletes who have reached a plateau in muscle mass and strength. It has been proposed that achieving a high degree of muscle fibre recruitment is important for inducing muscle hypertrophy with BFRRE, and the available evidence suggest that fatiguing low-load exercise during ischemic conditions can recruit both slow (type I) and fast (type II) muscle fibres. Nevertheless, closer scrutiny reveals that type II fibre activation in BFRRE has to date largely been inferred using indirect methods such as electromyography and magnetic resonance spectroscopy, while only rarely addressed using more direct methods such as measurements of glycogen stores and phosphocreatine levels in muscle fibres. Hence, considerable uncertainity exists about the specific pattern of muscle fibre activation during BFRRE. Therefore, the purpose of this narrative review was (1) to summarize the evidence on muscle fibre recruitment during BFRRE as revealed by various methods employed for determining muscle fibre usage during exercise, and (2) to discuss reported findings in light of the specific advantages and limitations associated with these methods. © 2019 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd
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