We present our expeilence of pedicled Anterolateral thigh flap for reconstruction of groin defects in cancer patients. Total of 17 flaps in 16 patients were performed between January 2001 to May ...2003. 15 flaps were used for groin defects after node dissection for carcinoma of Penis (bilateral groin defects in one patient), 1 case of Squamous Cell Carcinoma of groin and 1 case of Soft Tissue Sarcoma of groin. All patients were male. 16 were myocutaneous variety and 1 was fasciocutaneous flap based on the septocutaneous perforator. Complications were few and all patients achieved durable long-term coverage. We found the flap to be technically easy and reliable.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Motor unit firing and contractile properties during a submaximal contraction until failure were assessed with a new tracking technique. Two distinct phases in firing behavior were observed, which ...compensated for changes in twitch area and predicted time to failure. However, the late increase in firing rate was below the rates attained in the absence of fatigue, which points to an inability of the central nervous system to sufficiently increase the neural drive to muscle with fatigue.
We investigated changes in motor unit (MU) behavior and vasti-muscle contractile properties during sustained submaximal fatiguing contractions with a new time-domain tracking technique to understand the mechanisms responsible for task failure. Sixteen participants performed a nonfatiguing 15-s isometric knee extension at 50% of the maximum voluntary (MVC) torque, followed by a 30% MVC sustained contraction until exhaustion. Two grids of 64 surface electromyography electrodes were placed over vastus medialis and lateralis. Signals were decomposed into MU discharge times and the MUs from the 30% MVC sustained contraction were followed until task failure by overlapping decomposition intervals. These MUs were then tracked between 50% and 30% MVC. During the sustained fatiguing contraction, MUs of the two muscles decreased their discharge rate until ∼40% of the endurance time, referred to as the reversal time, and then increased their discharge rate until task failure. This reversal in firing behavior predicted total endurance time and was matched by opposite changes in twitch force (increase followed by a decrease). Despite the later increase in MU firing rates, peak discharge rates at task failure did not reach the frequency attained during a nonfatiguing 50% MVC contraction. These results show that changes in MU firing properties are influenced by adjustments in contractile properties during the course of the contraction, allowing the identification of two phases. Nevertheless, the contraction cannot be sustained, possibly because of progressive motoneuron inhibition/decreased excitability, as the later increase in firing rate saturates at a much lower frequency compared with a higher-force nonfatiguing contraction.
NEW & NOTEWORTHY Motor unit firing and contractile properties during a submaximal contraction until failure were assessed with a new tracking technique. Two distinct phases in firing behavior were observed, which compensated for changes in twitch area and predicted time to failure. However, the late increase in firing rate was below the rates attained in absence of fatigue, which points to an inability of the central nervous system to sufficiently increase the neural drive to muscle with fatigue.
The purpose of this study is to compare the effect of two types of quadriceps strengthening protocols on morphological characteristics of the knee vastus muscles in patients with lateral patellar ...compression syndrome.
48 female patients were randomly divided into 3 groups: selective (16), general (17) and control (15). The selective group participated in an isokinetic knee extension training protocol at the last 30° knee extension arc with maximum leg external rotation at high speed with the aim of selectively strengthening the vastus medialis muscle. The general group participated in an exercise protocol aimed at strengthening the entire quadriceps muscle. Both these protocols lasted 8 weeks. The control group did not receive any intervention. The vastus medialis and lateralis muscles cross-sections and fibers angles were measured using an ultrasound device. The data were analyzed using repeated-measures ANOVA and dependent t tests.
At pre-intervention, there were no differences between groups in muscles cross-sections and fiber angles (P > 0.05), but after interventions, in selective group, the vastus medialis cross-section and fiber angle, as well as vastus medialis to vastus lateralis cross-section ratio, were significantly higher than other groups (P < 0.01). Also, compared to pre-intervention, the vastus medialis cross-section and fiber angle increased only in selective group (P = 0.001), and the vastus lateralis cross-section increased only in general group (P = 0.001).
Use of isokinetic extension exercises targeting selectively strengthening the vastus medialis can improve the activity and involvement of this muscle-which is impaired in chronic patellofemoral joint disorders - by changing its morphology.
•Isokinetic knee extension exercise to selectively strengthen vastus medialis significantly increases the muscle fiber angle.•It also significantly increases the vastus medialis cross-section and the ratio of its cross-section to the vastus lateralis. It can improve the vastus medialis function, which is impaired in chronic patellofemoral disorders, by changing its morphology.
This study aimed to compare the vastus medialis and vastus lateralis muscle activations during squat exercises performed on different surfaces. Recreationally active 14 males (age: 20.43±1.28 years; ...height: 176.94±6.58 cm; body weight: 72.78±10.72 kg) participated in this study. A ground surface is used as a stable surface, a gymnastics mat and a Bosu ball are used as an unstable surface. Participants performed two sets of squats on three surfaces and ten repetitions of each set. Participants performed squat exercises with their body weight. Muscle activation measurements were made from the vastus medialis and vastus lateralis muscles during the squat movement on each surface. A one-way repeated-measures analysis of variances was used to statistically compare muscle activations between surfaces. As a result of statistical analysis, no significant differences were found in the vastus medialis and vastus lateralis muscle activations between surfaces (p>0.05). In conclusion, it was determined that the vastus medialis and vastus lateralis muscle activation in the squat movement was not affected by the stability of the surfaces. Therefore, it can be suggested that the surfaces used in this study can be used interchangeably for vastus medialis (VM) and vastus lateralis (VL) muscle activation in the squat exercise.
Different strategies for near-infrared spectroscopy (NIRS)-derived muscle oxidative capacity assessment have been reported. This study compared and evaluated (I) approaches for averaging trials; (II) ...NIRS signals and blood volume correction equations; (III) the assessment of vastus lateralis (VL) and tibialis anterior (TA) muscles in two fitness levels groups.
Thirty-six participants 18 chronically trained (CT: 14 males, 4 females) and 18 untrained (UT: 10 males, 8 females) participated in this study. Two trials of twenty transient arterial occlusions were performed for NIRS-derived muscle oxidative capacity assessment. Muscle oxygen consumption (Formula: see textO
m) was estimated from deoxygenated hemoglobin (HHb), corrected for blood volume changes following Ryan (HHbR) and Beever (HHbB) equations, and from oxygen saturation (StO
) in VL and TA.
Superimposing or averaging Formula: see textO
m or averaging the rate constants (k) from the two trials resulted in equivalent k values two one-sided tests (TOST) procedure with 5% equivalence margin-P < 0.001. Whereas HHbR (2.35 ± 0.61 min
) and HHbB (2.34 ± 0.58 min
) derived k were equivalent (P < 0.001), StO
derived k (2.81 ± 0.92 min
) was greater (P < 0.001) than both. k values were greater in CT vs UT in both muscles (VL: + 0.68 min
, P = 0.002; TA: + 0.43 min
, P = 0.01).
Different approaches for averaging trials lead to similar k. HHb and StO
signals provided different k, although different blood volume corrections did not impact k. Group differences in k were detected in both muscles.
At a constant power output, cyclists prefer to use a higher cadence than those that minimize metabolic cost. The neuromuscular mechanism underpinning the preferred higher cadence remains unclear.
...PURPOSEThe aim of this study was to investigate the effect of cadence on joint level work and vastus lateralis (VL) fascicle mechanics while cycling at a constant, submaximal, power output. We hypothesized that preferred cycling cadence would enhance the power capacity of the VL muscle when compared with a more economical cadence. Furthermore, we predicted that the most economical cadence would coincide with minimal total electromyographic activity from the leg muscles.
METHODSMetabolic cost, lower-limb kinematics, joint level work, VL fascicle mechanics, and muscle activation of the VL, rectus femoris, biceps femoris, gastrocnemius medialis, and soleus muscles were measured during cycling at a constant power output of 2.5 W·kg and cadences of 40, 60, 80, and 100 rpm. A preferred condition was also performed where cadence feedback was hidden from the participant.
RESULTSMetabolic cost was lowest at 60 rpm, but the mean preferred cadence was 81 rpm. The distribution of joint work remained constant across cadences, with the majority of positive work being performed at the knee. The preferred cadence coincided with the highest VL power capacity, without a significant penalty to efficiency, based on fascicle shortening velocity.
CONCLUSIONSCycling at a higher cadence is preferred to ensure that the muscle’s ability to produce positive power remains high. Further investigations are required to examine what feedback mechanism could be responsible for the optimization of this motor pattern.
Aims
Motor unit recruitment and firing rate patterns of the vastus lateralis (VL) have not been compared between sexes during moderate‐ and high‐intensity contraction intensities. Additionally, the ...influence of fiber composition on potential sex‐related differences remains unquantified.
Methods
Eleven males and 11 females performed 40% and 70% maximal voluntary contractions (MVCs). Surface electromyographic (EMG) signals recorded from the VL were decomposed. Recruitment thresholds (RTs), MU action potential amplitudes (MUAPAMP), initial firing rates (IFRs), mean firing rates (MFRs), and normalized EMG amplitude (N‐EMGRMS) at steady torque were analyzed. Y‐intercepts and slopes were calculated for MUAPAMP, IFR, and MFR versus RT relationships. Type I myosin heavy chain isoform (MHC) was determined with muscle biopsies.
Results
There were no sex‐related differences in MU characteristics at 40% MVC. At 70% MVC, males exhibited greater slopes (p = 0.002) for the MUAPAMP, whereas females displayed greater slopes (p = 0.001–0.007) for the IFR and MFR versus RT relationships. N‐EMGRMS at 70% MVC was greater for females (p < 0.001). Type I %MHC was greater for females (p = 0.006), and was correlated (p = 0.018–0.031) with the slopes for the MUAPAMP, IFR, and MFR versus RT relationships at 70% MVC (r = −0.599–0.585).
Conclusion
Both sexes exhibited an inverse relationship between MU firing rates and recruitment thresholds. However, the sex‐related differences in MU recruitment and firing rate patterns and N‐EMGRMS at 70% MVC were likely due to greater type I% MHC and smaller twitch forces of the higher threshold MUs for the females. Evidence is provided that muscle fiber composition may explain divergent MU behavior between sexes.
Protocols for high-resolution respirometry (HRR) of intact cells, permeabilized cells, and permeabilized muscle fibers offer sensitive diagnostic tests of integrated mitochondrial function using ...standard cell culture techniques and small needle biopsies of muscle. Multiple substrate–uncoupler–inhibitor titration (SUIT) protocols for analysis of oxidative phosphorylation improve our understanding of mitochondrial respiratory control and the pathophysiology of mitochondrial diseases. Respiratory states are defined in functional terms to account for the network of metabolic interactions in complex SUIT protocols with stepwise modulation of coupling and substrate control. A regulated degree of intrinsic uncoupling is a hallmark of oxidative phosphorylation, whereas pathological and toxicological dyscoupling is evaluated as a mitochondrial defect. The noncoupled state of maximum respiration is experimentally induced by titration of established uncouplers (FCCP, DNP) to collapse the proton gradient across the mitochondrial inner membrane and measure the capacity of the electron transfer system (ETS, open-circuit operation of respiration). Intrinsic uncoupling and dyscoupling are evaluated as the flux control ratio between nonphosphorylating LEAK respiration (electron flow coupled to proton pumping to compensate for proton leaks) and ETS capacity. If OXPHOS capacity (maximally ADP-stimulated oxygen flux) is less than ETS capacity, the phosphorylation system contributes to flux control. Physiological Complex I + II substrate combinations are required to reconstitute TCA cycle function. This supports maximum ETS and OXPHOS capacities, due to the additive effect of multiple electron supply pathways converging at the Q-junction. Substrate control with electron entry separately through Complex I (pyruvate + malate or glutamate + malate) or Complex II (succinate + rotenone) restricts ETS capacity and artificially enhances flux control upstream of the Q-cycle, providing diagnostic information on specific branches of the ETS. Oxygen levels are maintained above air saturation in protocols with permeabilized muscle fibers to avoid experimental oxygen limitation of respiration. Standardized two-point calibration of the polarographic oxygen sensor (static sensor calibration), calibration of the sensor response time (dynamic sensor calibration), and evaluation of instrumental background oxygen flux (systemic flux compensation) provide the unique experimental basis for high accuracy of quantitative results and quality control in HRR.
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