This invention pertains to pneumatic tourniquet systems used for muscle and blood vessel conditioning with reduced arterial and venous blood flow in the limb during any type of muscle contractions, or stopping the penetration of the arterial blood into patient's limb during surgery in order to facilitate the procedure. In particular, this invention pertains to pneumatic tourniquet system with double-chambre pneumatic cuff. When cuff is filled with two different pressures it allows for asymmetric compression of any human limb and hence more comfortable and accurate control of the level of blood flow reduction in the said limb. The device is used mainly for muscle conditioning in physiotherapy, rehabilitation and sports.
F.32 International patent
COBISS.SI-ID: 5221483INTRODUCTION: Quadriceps femoris (QF) muscle atrophy and weakness are the most common factors influencing poor functional outcomes in patients, following knee injury or surgery. Skeletal muscle atrophy is a consequence of unloading and arthrogenic muscle inhibition, as well as ischemic-reperfusion injury following prolonged period of ischemia applied during the surgical procedure. Several animal studies suggest, that short term ischemic preconditioning evokes protective mechanisms that subsequently decrease the ischemic-reperfusion damage to the tissues. Additionally, low load resistance exercise with blood flow restriction (ischemic exercise) proved to be similarly effective compared to standard high load resistance exercise in terms of muscle mass gain in healthy individuals. This study aims to test the effects of short term preoperative ischemic exercise on postoperative QF muscle atrophy and weakness. METHODS: Twenty patients of both sexes undergoing ACL reconstruction were included in our study. Experimental protocol involved 5 exercise units of ischemic unilateral knee extension (ISH group) during the last 10 days pre surgery. Second group executed matching protocol with only virtual blood flow restriction (PLACEBO group). Muscle volume was assessed by MRI preoperatively as well as 4 and 12 weeks following reconstruction. Muscle function was assessed by measuring maximal isometric voluntary contraction, submaximal isometric endurance testing and single leg squat. Muscle activation of vastus medialis was measured by EMG and oxygen kinetics of vastus lateralis was measured with infra-red laser spectroscopy. RESULTS: There were no significant differences in QF atrophy 4 and 12 weeks post-surgery between the groups (ISH -19.8 ± 4.9% and -16.1 ± 3.7% vs. PLACEBO -23.0 ± 9.5% and -20.2 ± 10.6%). Maximal isometric torque deficits of affected leg showed similar trends as muscle volumes. There were no significant differences between the groups in single leg squat. On the contrary, isometric endurance times 4 weeks post reconstruction ISH group endured significantly longer times compared to PLACEBO group (p=0.002). At the same time point ISH group also had significantly better muscle activation (p=0.049= and significantly higher muscle blood flow (p=0.010). CONCLUSION: Short term preconditioning with ischemic exercise had significantly positive effects on muscle endurance compared to comparable amount of exercise without blood flow restriction. Patients achieved better endurance with better motor unit recrutation and improved muscle blood flow. However, there was no positive effect of preoperative ischemic exercise on postoperative muscle atrophy and strength. In order to get the clearer view on the effects of preconditioning, additional research is necessary. Along with a longer preoperative program, the influence of postoperative low load ischemic exercise should be thoroughly studied.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 288038656The main aim of this study was to examine whether six weeks of low-load BFR-RE performed at a moderate training frequency was sufficient to induce superior adaptations of skeletal muscle performance and morphology than load-volume matched free flow exercise. With institutional ethical approval 7 healthy active males (age: 22 ± 1 years; height 180.7 ± 4.0 cm; body mass: 85.4 ± 16.1 kg; mean ±SD) performed six weeks of single-leg knee extensor resistance exercise (3 sets, 3 days per week) at a load equivalent to 50RM. In a randomised manner, one limb was trained with BFR (~100 mmHg) to volitional failure, the contralateral limb performed free-flow exercise (CON) matched for load and work. Before and after training maximal isometric (MVC) and isokinetic (60 and 180 °s-1) knee extensor strength were assessed. Muscle biopsies (vastus lateralis) were examined for changes in myofibre cross sectional area (MCSA), myonuclei number, satellite cell (SC) content and capillary number/density. Data were analysed with repeated measures two-way ANOVAs and Wilcoxon signed rank tests. Exercise workload (kg x reps) increased (P ( 0.01) throughout the intervention. MVC increased (P ( 0.05) by a similar extent in BFR (290 ± 72 to 306 ± 70 Nm; 6.5%) and CON (293 ± 65 to 320 ± 78 Nm; 8.8%), however isokinetic strength remained unchanged. MCSA, myonuclei number or capillary content did not change in BFR or CON. Satellite cell density decreased (P ( 0.05) from 16.7 ± 6.3 to 13.2 ± 4.6 SC mm-2 in BFR with no change in CON. These preliminary data indicate that six weeks of low-load BFR-RE performed three days per week is not sufficient to elicit measureable hypertrophic changes nor to cause elevated myogenic SC content or produce gains in myonuclei number and capillary content. In addition, strength gains of low-frequency BFR-RE are not superior to those of free flow exercise of equal training volume.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 5210475This invention pertains to pneumatic tourniquet systems used for muscle and blood vessel conditioning with reduced arterial and venous blood flow in the limb during any type of muscle contractions, or stopping the penetration of the arterial blood into patient's limb during surgery in order to facilitate the procedure. In particular, this invention pertains to pneumatic tourniquet system with double-chambre pneumatic cuff. When cuff is filled with two different pressures it allows for asymmetric compression of any human limb and hence more comfortable and accurate control of the level of blood flow reduction in the said limb. The device is used mainly for muscle conditioning in physiotherapy, rehabilitation and sports.
F.06 Development of a new product
Aim: Present study assessed if effects of short-term preconditioning with ischemic exercise can preserve Quadriceps Femoris muscle endurance within the first 12 wks after ACL reconstruction. Methods:Twenty subjects, undergoing ACL reconstruction with ipsilateral hamstrings autographs, performed 5 exercise sessions during the last 10 days before surgery. They were quasi-randomly assigned into two groups: ISHEMIC group - performing low-load blood flow restricted (ischemic) knee-extension exercise or SHAM group – replicating the same exercise volume with free blood flow. Tissue hemoglobine kinetics (NIRS) and surface EMG were measured on QF muscle during isometric contraction performed at 30% MVIC torque to volitional failure prior to preconditioning and at 4 and 12 weeks post-surgery. Results:Time of sustained QF contraction decreased (p=0.002) in SHAM group by 100±91 s at 4 wks and returned to preoperative values at 12 wks. No decline in contraction time was observed in ISCHEMIC group at 4 wks, whereas an increase of 54±50 s was observed at 12 wks post-surgery. A 33±8% increase (p=0.018) in RMS EMG amplitude, with concomitant 56±16% increase (p=0.010) in muscle blood flow, was observed only in ISCHEMIC group at 4 wks after surgery. Discussion:This is the first study to demonstrate a positive effect of short-term ischemic exercise preconditioning on QF muscle endurance in patients after arthroscopic ACL reconstruction. Enhanced endurance of QF muscle was brought about by augmented muscle fibre recruitment for the given torque output. This most likely resulted from combination of preserved muscle activation capacity and enhanced reguation of oxygen delivery to the muscle. The latter may be an evidence of perserving effect of ischemic preconditioning on density and function of muscle microcirculation within first 4 wks after surgery with prolonged tourniquet application.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 5073771