Purpose: This randomized controlled study assessed whether muscle preconditioning with ischemic exercise can prevent loss of quadriceps femoris volume, strength, and function after anterior cruciate ligament (ACL) reconstruction. Methods: Twenty subjects scheduled for ACL reconstruction with autologous hamstring grafts performed 5 exercise sessions during the last 10 days before surgery. They were randomly assigned into two groups: ISHEMIC – performing low-load ischemic knee-extension exercise with pneumatic tourniquet inflated to 150 mmHg, or SHAM – kneeextension exercise with tourniquet inflated to 20 mmHg. Quadriceps femoris (QF) volume (measured by MRI), maximal voluntary isometric contraction torque, and single-leg anterior reach distance were assessed prior to preconditioning and repeated at 4 and 12 weeks post-surgery. Results: There were no significant differences between the groups in any of the measured variables prior to or after surgery. The deficit in QF vastii volume increased to 20±5 % in ISCHEMIC and 23±10 % in SHAM group at 4 weeks and persisted at 16±4 % in ISCHEMIC and 20±11 % in SHAM group at 12 weeks post-surgery. There were no statistically significant differences in rectus femoris volumes. Likewise, the deficit in QF maximal isometric torque persisted at 15±15 % in ISCHEMIC and 22±16 % in SHAM at 12 weeks post-surgery. There were no significant differences between groups in single-leg reach distance deficit. Conclusions: Muscle preconditioning with short ischemic exercise showed no protective effect on QF muscle mass, isometric strength, or knee functional loss in patients undergoing ACL reconstruction. Moreover, all patients reached similar level of QF muscle atrophy and strength deficit regardless of their pre-operative muscular status.
COBISS.SI-ID: 5064811
Blood flow restricted resistance (BFRR) training with pneumatic tourniquet has been suggested as an alternative for conventional weight training due to the proven benefits for muscle strength and hypertrophy using relatively low resistance, hence reducing the mechanical stress across a joint. As such, it has become an important part of rehabilitation programs used in either injured or operated athletes. Despite a general consensus on effectiveness of BFRR training for muscle conditioning, there are several uncertainties regarding the interplay of various extrinsic and intrinsic factors on its safety and efficiency, which is being reviewed from aclinical perspective. Among extrinsic factors tourniquet cuff pressure, size and shape have been identified as key for safety and efficiency. Among intrinsic factors, limb anthropometrics, patient history and presence of cardiac, vascular, metabolic or peripheral neurologic conditions have been recognized as most important. Though there are a few potential safety concerns connected to BFRR training, the following have been identified as the most probable and health-hazardous: (a) mechanical injury to the skin, muscle, and peripheral nerves, (b) venous thrombosis due to vascular damage and disturbed hemodynamics and (c) augmented arterial blood pressure responses due to combined high body exertion and increased peripheral vascular resistance. Based on reviewed literature and authors’ personal experience with use of BFRR training in injured athletes, guidelines for its safe application are outlined. Also, a comprehensive risk assessment tool for screening of subjects prior to their inclusion in a BFRR training program is being introduced.
COBISS.SI-ID: 4978795
Muscle atrophy is one of major causes of poor functional status of patients following injuries and surgical procedures of musculo-skeletal structures. Ischemia-reperfusion (I-R) injury, caused by sustained ischemia during surgery greatly influences the development of atrophy. A short termed intermittent periods of ischemia and reperfusion – so called ischemic (pre)conditioning (IP) has positive effects on attenuation of I-R injury. Research presents evidence of increased cell viability, decreased cell injury and preservation of energy stores in preconditioned subjects. Despite the evidence, long term effects of IP on development of muscle atrophy have not yet been investigated. There is a need for determination of optimal IP protocol for clinical practice. Accurate measurements of cross-sectional area or muscle volume with magnetic resonance imaging, standardized muscle strength and function tests performed in crucial time intervals following surgery are the next logical step in the research of long-term effects of IP on human skeletal muscle.
COBISS.SI-ID: 4503403
Skeletal muscle weakness is inevitable negative effect of injury, disease or surgery of joints. Key factors of muscle deconditioning are 1) muscle atrophy and 2) arthrogenic muscle inhibition (AMI); however their interaction and underlying mechanisms are still unclear. The AMI origin from either knee or hip joint has been demonstrated to predominantly affect Quadriceps Femoris muscle. However, the role of AMI in development of muscle weakness in various muscle groups and joint conditions remains equivocal. Physiotherapeutic modalities work through various physiological pathways; their efficiency thus depends on the primary cause of muscle weakness in a given individual. In case where AMI is predominantly caused by reflex neural inhibition, peripheral neuromuscular electric stimulation used in conjunction with voluntary contraction proved efficient. The inhibitory neural inflow from the affected joint can be attenuated prior to muscle activation by application of cryotherapy or TENS over the affected joint. If AMI is primarily driven by inhibition of upper motor neurons, transcranial magnetic stimulation of motor cortex has been shown effective, however technical limitations hinder its more widespread clinical use. To tackle disuse muscle atrophy, the range of effective modalities is substantially narrowed due to developed AMI and limitations of mechanical loading of the affected joint. Apart from neuromuscular electric stimulation, muscle vibration exercise and low-load resistance exercise with blood flow restriction in active muscles (ischemic exercise) may have potential for counteracting development of disuse atrophy. Given that disuse muscle atrophy affects primarily Type I fibres and adjacent muscle capillary network, there is a lot of therapeutic potential in ischemic exercise. Efficiency and safety of these modalities in various pathologic conditions needs to be scrutinized in future studies.
COBISS.SI-ID: 5006699
Background: Factors predicting Quadriceps Femoris muscle (QF) atrophy during the early period after arthroscopic ACL reconstruction has not been extensively studied. It is also equivocal whether muscle atrophy is a key determinant of postoperative QF weakness. Methods: Mean changes in QF volume, MVIC torque and isometric endurance time were analysed in 25 patients prior to and at four (POST-4w) and twelve (POST-12w) weeks after surgery. Multivariable regression model of change in QF volume was made from preoperative QF volume deficit, MVIC torque and isometric endurance time combined with postoperative changes in knee extension ROM and mid-patellar girth. The contribution of QF atrophy to MVIC torque change was evaluated with univariate regression and MVIC torque to volume ratio at POST-12w only. Results: QF volume and MVIC torque were reduced throughout the recovery period, whereas endurance time was decreased only at POST-4w. The model of QF volume change was significant (p(0.01) only at POST-4w, explaining 57% of its variation, where endurance time had a negative and knee extension ROM deficit a positive weight. Change in QF volume explained (p(0.05) 46% of the MVIC torque variation at POST-12w. Also, a significant change (p(0.05) in QF MVIC torque to volume ratio was observed at POST-12w. Conclusions: Good prediction of QF atrophy in the first postoperative month can be made from studied variables, with isometric endurance and knee extension ROM deficit being the most significant contributors. The atrophy explained larger part of QF muscle weakness, whereas factors contributing to the remaining portion need further research.
COBISS.SI-ID: 5222251