Blood flow-restricted strength training displays high functional and biological efficacy in women: a within-subject comparison with high-load strength training

Limited data exist on the efficacy of low-load blood flow-restricted strength training (BFR), as compared directly to heavy-load strength training (HST). Here, we show that 12 wk of twice-a-week unilateral BFR [30% of one repetition maximum (1RM) to exhaustion] and HST (6-10RM) of knee extensors provide similar increases in 1RM knee extension and cross-sectional area of distal parts of musculus quadriceps femoris in nine untrained women (age 22 ± 1 yr). The two protocols resulted in similar acute increases in serum levels of human growth hormone. On the cellular level, 12 wk of BFR and HST resulted in similar shifts in muscle fiber composition in musculus vastus lateralis, evident as increased MyHC2A proportions and decreased MyHC2X proportions. They also resulted in similar changes of the expression of 29 genes involved in skeletal muscle function, measured both in a rested state following 12 wk of training and subsequent to singular training sessions. Training had no effect on myonuclei proportions. Of particular interest, 1) gross adaptations to BFR and HST were greater in individuals with higher proportions of type 2 fibers, 2) both BFR and HST resulted in approximately four-fold increases in the expression of the novel exercise-responsive gene Syndecan-4, and 3) BFR provided lesser hypertrophy than HST in the proximal half of musculus quadriceps femoris and also in CSApeak, potentially being a consequence of pressure from the tourniquet utilized to achieve blood flow restriction. In conclusion, BFR and HST of knee extensors resulted in similar adaptations in functional, physiological, and cell biological parameters in untrained women.

Changes in the chemical composition of Musculus quadriceps femoris of beef kept at different temperatures

The study contains the result from the test f the vacuum - packed meat sliices ( M.quadriceps femoris) obtained from ox Simmental breed. After the primary treatment, the refrigeration an the sorting out , the meat slices were vacuum -packed and kept and a temperature of 4?C and 6?C. At the 2nd, the 3rd and the 5th day, a chemical analysis of the meat slices was made. At the 2nd and the 5th day it was made a microbiological test of the meat slices in relation to the overall number of bacteria, as well as a sensor analysis in terms of outward appearance, consistence, color, odor and taste. It was noted that, during the storage the water content in the meat slices significantly reduced, and the fat, protein and mineral substance content was increased. The overall number of bacteria was increased in the meat slices kept at a temperature of 6?C. The best sensor marks were given to the meat slices kept at a temperature of 4?C.

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

This study tested the hypothesis that fatigue of a single member of musculus quadriceps femoris (QF) would alter use of the other three muscles during knee extension exercise (KEE). Six men performed KEE with the left QF at a load equal to 50% of the 4 × 10 repetitions maximum. Subsequently, electromyostimulation (EMS), intended to stimulate and fatigue the left m. vastus lateralis (VL), was applied for 30 min. Immediately after EMS, subjects repeated the KEE. Transverse relaxation time (T2)-weighted magnetic resonance images were taken before and after each bout of KEE and at 3 and 30 min of EMS to assess use and stimulation, respectively, of the QF. T2 of each of the QF muscles was increased 8–13% after the first KEE. During EMS, T2 increased ( P < 0.05) even more in VL (10%), whereas it decreased ( P < 0.05) to pre-KEE levels in m. vastus medials (VM) and m. rectus femoris (RF). The VL and, to some extent, the m. vastus intermedius were stimulated, whereas the VM and RF were not, thereby recovering from the first bout of KEE. Isometric torque, initially 30% of maximal voluntary, was reduced to 13% at 3 min and 7% at 30 min. T2 was greater ( P < 0.05) after the second than the first bout of KEE, especially the increase for the VM and RF. These results suggest that subjects were able to perform the second bout with little contribution of the VL by greater use of the other QF muscles. The simplest explanation is increased central command to the QF such that the intended act could be accomplished despite acute fatigue of one of its synergists.

Electroneuromyographic investigations in patients with deforming arthrosis of the hip and knee joints

The changes of the functional state of spinal centers and muscles (musculus quadriceps femoris and musculus triceps surae) are detected, when observing 8 healthy subjects and 16 patients with gonand coxarthrosis. Centers or center-controlled muscles suffer to a large extent depending on the occurrence of the joint affections.