Myoglobin Concentration Research Articles

Rapid and Effective Elimination of Myoglobin with CytoSorb® Hemoadsorber in Patients with Severe Rhabdomyolysis

Introduction: Rhabdomyolysis is characterized by destruction of muscle fibers by various causes and is diagnosed by increased creatine kinase concentrations in the blood. Myoglobin released into the blood may cause acute kidney injury. In this randomized controlled study, we hypothesized that myoglobin elimination would be faster when a hemoadsorber was added to a continuous veno-venous hemodialysis (CVVHD). Methods: Four patients in the control group received CVVHD with a high cut-off hemofilter using high blood and dialysate flows for 48 h. Four patients in the CytoSorb group received the same treatment, but in addition, the hemoadsorber CytoSorb^® was inserted in front of the hemofilter and replaced once after 24 h. Blood samples were drawn simultaneously before (pre) and after (post) the hemofilter or else the hemoadsorber, after 5 and 30 min, as well as after 2, 4, 8, and 24 h. All measurements were repeated the next day after the hemoadsorber had been renewed in the CytoSorb group. Primary outcome was the area under the curve (AUC) of the relative myoglobin concentrations as percent of baseline. To evaluate the efficacy of myoglobin removal, relative reductions in myoglobin concentrations during one passage through each device at each time point were calculated. Results: Patients in the CytoSorb group had a significantly lower AUC during the first 24 h (42 ± 10% vs. 63 ± 6%, p = 0.029) as well as during the observation period of 48 h (26 ± 7% vs. 51 ± 12%, p = 0.029). The relative reductions for myoglobin were considerably higher in the CytoSorb group compared to the control group during the first 8 h. Conclusion: Myoglobin concentrations declined considerably faster when CytoSorb was added to a CVVHD. When compared to a high-cut-off hemofilter, efficacy of CytoSorb in myoglobin elimination was much better. Because of saturation after 8–12 h an exchange may be necessary.

Multiple cryosauna sessions for post-exercise recovery of delayed onset muscle soreness (DOMS): a randomized control trial.

The main goal was to investigate the effectiveness of cryosauna in preventing the development of delayed onset muscle soreness and to analyze the regenerative changes within muscles after acute fatigue-induced exercises. Thirty-one volunteers were assigned into two groups: 1) an intervention group that participated in cryostimulation after fatigue-induced exercise protocol (CRYO, n = 16) and a control group that performed fatigue-induced exercise protocol, but without any intervention (CONT, n = 15). Main outcome measures include at baseline: blood sample testing (leukocyte content, myoglobin concentration, and creatine kinase activity) and muscle stiffness of lower extremity; immediately after (stiffness), and 24-48-72-96h post-exercise (blood samples and stiffness). Both groups performed an exercise-induced muscle damage protocol based on repeated countermovement jumps (10 sets, 10 repetitions). The CRYO group underwent a cryosauna (temperature: -110°C, time: 1.5min per session) intervention during four sessions (i.e., immediately after, 24-48-72h post-exercise). Leukocyte content was significantly greater 24-48-72h after exercise in CONT, compared with the CRYO group (p ≤ 0.05 for all), while creatine kinase activity was greater 24-48-96h in CONT, compared with the CRYO group (p ≤ 0.05 for all). Muscle stiffness increased significantly in rectus femoris, tibialis anterior, and fibula muscle after 48h post-exercise (p ≤ 0.05 for all), as well as in tibialis anterior and fibula after 72h post-exercise (p ≤ 0.05 for all) in the CRYO group. Multiple cryosauna was an effective recovery strategy that reduced blood biomarkers and muscle stiffness after exercise-induced muscle damage. Moreover, the development of delayed onset muscle soreness, expressed by a greater muscle stiffness post-exercise, was attenuated to the first 48h.

Plasma myoglobin indicates muscle damage associated with acceleration/deceleration during football.

Monitoring muscle damage in athletes assists not only coaches to adjust the training workload but also medical staff to prevent injury. Measuring blood myoglobin concentration can help evaluate muscle damage. The novel portable device utilized in this study allows for easy on-site measurement of myoglobin, providing real-time data on the player's muscle damage. This study investigated the relationship between external load (global positioning system parameters) and internal loads (myoglobin concentration and creatine kinase activity) in 15 male professional football players before and after a match. Whole blood samples from participants' fingertips were collected before the match (baseline) and at 2, 16, and 40 h after the match. Myoglobin concentrations were measured using the IA-100 compact immunoassay system. Creatine kinase concentrations were measured in a clinical laboratory, and match loads were monitored using a global positioning system device. The mean myoglobin concentration was significantly higher at 2 h than at the other time points (P<0.05), and decreased to baseline levels within 16 h post-match. The mean creatine kinase concentration increased after the match but did not reach a significant level. Muscle damage monitored by myoglobin after football match-play was strongly associated with acceleration/deceleration metrics rather than the sprint/high-speed running distance. Our findings indicate that myoglobin is a more sensitive marker of muscle damage than creatine kinase after football match-play. Monitoring myoglobin in athletes can aid in determining their recovery status from the previous training load and help practitioners manage the training load.

The Levels of Markers of Muscle Damage, Inflammation, and Heat Shock Proteins in Judokas and the Extent of Their Changes during a Special Performance Test at Different Ambient Temperatures

Background: Athletes in combat sports, such as judo, often experience muscle cell damage due to physical and metabolic stress. This study investigates the impact of anaerobic interval exercises involving both upper and lower limbs at different temperatures on physiological indicators. Methods: Fifteen judokas, with an average age of 20.7 ± 2.0 years, participated in the study. They had an average body height of 178 ± 6.3 cm, body mass of 76.3 ± 12.6 kg, VO2max of 43.2 ± 7.8 mL·kg−1, and peak power of 12.1 W·kg−1. The main experiment involved performing five sequences of pulsating exercise on a cycle ergometer for both upper and lower limbs. This was conducted in a thermoclimatic chamber set at temperatures of 21 ± 0.5 °C and 31 ± 0.5 °C with a relative humidity of 50 ± 5%. The sequences alternated pulsations of varying durations and loads between the upper and lower limbs, with a 15 min break following each sequence. Within each sequence, participants underwent four anaerobic limb tests. Biochemical markers, including interleukin-1β (IL-1β), interleukin-6 (IL-6), and heat shock protein 70 (HSP70), were measured using the enzyme-linked immunosorbent assay (ELISA) method before and after exercise, and again at 1, 24, and 48 h post-exercise. Muscle cell damage was evaluated based on lactate dehydrogenase (LDH) activity and myoglobin (Mb) concentration. Results: Both temperature conditions elicited physiological and biochemical responses. Positive correlations were observed between white blood cell count (WBC) and LDH concentration at 21 °C, as well as between WBC and IL-6 at 21 °C. At 31 °C, correlations were seen between WBC and myoglobin, and WBC and LDH. Conclusions: Muscle cell damage was evident under both conditions, as indicated by increased myoglobin levels. These findings offer insights into training strategies and underscore the physiological responses observed in combat sports athletes.

Variable Control and Its Influence Before Urine Sample Analysis in a Field Environment.

Background and Objectives: The aim of the study was to store urine samples at different temperatures and humidity levels and analyze common biochemical test results and point-of-care testing (POCT) indicators according to different storage times and evaluate whether the samples should be centrifuged to study the best storage conditions for urine samples. Methods: Random midstream urine samples (100 mL) were collected from 10 healthy individuals. A portion of the samples was centrifuged. The remaining samples were not centrifuged and were stored under different temperature and humidity conditions for different periods. We measured urine indicators ([Na+], [K+], [Cl-], gamma-glutamyl transpeptidase [GGT], urea, and creatinine [Cr]) at 2, 4, 24, and 72 hours and 7 and 55 days, and we used POCT to measure myoglobin (Mb) and microalbumin (mAlb) concentrations. Results: Centrifugation of urine samples decreased the measured GGT and increased the measured Mb. In urine samples stored at 4°C and room temperature, electrolyte concentrations were scarcely affected by storage time. After storage at 50°C for 24 hours, the measured [Na+] and [Cl-] levels changed. Metabolites (urea and Cr) underwent no obvious change across temperatures. GGT did not change during long-term storage at 4°C. The mAlb level changed significantly only after storage at 4°C. When stored at 4°C, Mb changed little within 4 hours. Under humid conditions, [Na+] and [Cl-] increased significantly after 24 hours, and urea decreased significantly after 7 days of storage. Under dry storage conditions, urinary Cr and GGT decreased, and under humid conditions, these concentrations increased. At high humidity, mAlb increased significantly after 72 hours. Conclusions: Electrolyte and amino acid metabolite concentrations were less affected by storage time at 4°C and room temperature than at other temperatures. Some proteins are sensitive to environmental changes; samples collected for quantification of these proteins can be stored briefly at 4°C after centrifugation. Normal humidity conditions meet most physiological testing requirements.

Assessment of selected muscle damage markers and zonulin concentration after maximum-intensity exercise in men with type 1 diabetes treated with a personal insulin pump

AimExercise-induced muscle damage depends on exercise intensity and duration and on individual susceptibility. Mechanical and metabolic stress may disturb the intestinal microflora. The study evaluated selected muscle damage markers and zonulin concentration after maximum-intensity exercise in type 1 diabetes (T1D) men compared with healthy controls.MethodsThe study involved 16 T1D participants and 28 controls matched by age (22.7 [21.3–25.1] vs. 22.6 [20.9–26.3] years), body mass index (24.2 ± 1.6 vs. 24.2 ± 1.9 kg/m2), and body fat percentage (16.1 ± 5.2 vs. 14.9 ± 4.6%). The T1D group had 11.3 ± 5.1 years of diabetes duration and a suboptimal mean glycated haemoglobin level of 7.2 ± 1.1%. The subjects underwent a graded running treadmill test until exhaustion. Lactate concentration was assessed in arterialized blood at baseline and 3 and 20 min after the test. Cortisol, testosterone, tumour necrosis factor α, myoglobin, lactate dehydrogenase, zonulin, and vitamin D levels were evaluated in cubital fossa vein blood before and 60 min after the test.ResultsT1D patients presented higher baseline zonulin, myoglobin concentration, testosterone/cortisol ratio, and lower maximal oxygen uptake. On adjusting for the baseline values, the groups differed in zonulin, lactate dehydrogenase, and myoglobin levels, testosterone/cortisol ratio, and lactate concentration determined 20 min after exercise (P < 0.05).ConclusionMaximum-intensity exercise increased muscle and intestinal damage in T1D participants. In patients with lower physical activity, very-high-intensity exercise should be recommended with caution. Observing the anabolic-catabolic index may help individualize effort intensity in T1D individuals.

Serum myoglobin modulates kidney injury via inducing ferroptosis after exertional heatstroke.

Myoglobin released by rhabdomyolysis (RM) is considered to be involved in pathogenesis of kidney disease caused by crush injury, but whether high level of serum myoglobin predisposes patients to acute kidney injury (AKI) and its molecular mechanisms are still unclear in exertional heatstroke (EHS). We aimed to determine the association and potential mechanism of myoglobin and AKI, and further investigate the targeted therapeutic agents for myoglobinemia. Serum myoglobin concentrations in patients with EHS were measured at admission, 24 h and 48 h after admission and discharge. The risk of AKI at 48 h was the primary outcome; the secondary outcome was composite outcome events with myoglobin levels and AKI at discharge and death at 90 days. In experimental studies, we further investigated the mechanisms of human kidney proximal tubular (HK-2) cells that were exposed to human myoglobin under heat stress conditions and the effect of baicalein. Our measurements showed that the highest myoglobin quartile (vs. the lowest) had an adjusted odds ratio (OR) of 18.95 (95% confidence interval [CI], 6.00-59.83) for AKI and that the OR (vs. quartile 2) was 7.92 (95% CI, 1.62-38.89) for the secondary outcome. The survival rate of HK-2 cells treated with myoglobin under heat stress was significantly decreased, and the production of Fe2+ and reactive oxygen species (ROS) was markedly increased, accompanied by changes in ferroptosis proteins, including increased p53, decreased SLC7A11 and GPX4, and alterations in endoplasmic reticulum stress (ERS) marker proteins. Treatment with baicalein attenuated HK-2 cell ferroptosis induced by myoglobin under heat stress through inhibition of ERS. High myoglobin was associated with AKI in the EHS, and its mechanisms involved ERS-associated ferroptosis. Baicalein may be a potential therapeutic drug for the treatment of AKI in patients with high myoglobin induced by rhabdomyolysis following EHS.

Myoglobin content and oxidative status to understand meat products’ color: Phenomenological based model

Meat color is attributed to myoglobin concentration and redox state. Myoglobin is a water-soluble hemoprotein with iron in its prosthetic group, which defines myoglobin’s redox state via its valence state and ligand linked to the free coordination site. In fresh meat, myoglobin can be in one of three states in dynamic equilibrium: deoxymyoglobin, oxymyoglobin, and metmyoglobin. Myoglobin can chemically interact with numerous components in meat products, affecting its redox state. These structural alterations in myoglobin caused by processing conditions will affect its thermal stability and consequently meat product color. Presently, cured meat products are made with sodium nitrite, a curing agent that reacts with myoglobin in meat, forming nitrosomyoglobin, a stable compound that gives the final meat product a distinctive pink color. This work proposes a mathematical model for understanding myoglobin structural changes during the production of a cured meat product. Because of the phenomenological structure of the established model, valuable knowledge is obtained, allowing new possibilities to be explored in the color of meat products while considering the chemical state of myoglobin. The proposed phenomenological model is validated with an error of roughly 10%.

Comparison of the medium cutoff dialyzer and postdilution hemodiafiltration on the removal of small and middle molecule uremic toxins.

The medium cutoff (MCO) dialyzer increases the removal of several middle molecules more effectively than high-flux hemodialysis (HD). However, comparative data addressing the efficacy and safety of MCO dialyzers vs. postdilution hemodiafiltration (HDF) in Korean patients are lacking. Nine patients with chronic HD were included in this pre-post study. Patients underwent HD with an MCO dialyzer for 4 weeks, followed by a 2-week washout period using a high-flux dialyzer to minimize carryover effects, and then turned over to postdilution HDF for 4 weeks. Reduction ratios and differences in the uremic toxins before and after dialysis were calculated from the MCO dialysis, postdilution HDF, and high-flux HD. In the in vitro study, EA.hy926 cells were incubated with dialyzed serum. Compared to postdilution HDF, the MCO dialyzer achieved significantly higher reduction ratios for larger middle molecules (myoglobin, kappa free light chain [κFLC], and lambda FLC [λFLC]). Similarly, the differences in myoglobin, κFLC, and λFLC concentrations before and after the last dialysis session were significantly greater in MCO dialysis than in postdilution HDF. The expression of Bax and nuclear factor κB was decreased in the serum after dialysis with the MCO dialyzer than with HDF. Compared with high-volume postdilution HDF, MCO dialysis did not provide greater removal of molecules below 12,000 Da, whereas it was superior in the removal of larger uremic middle molecule toxins in patients with kidney failure. Moreover, these results may be expected to have an anti-apoptotic effect on the human endothelium.

Low myoglobin concentration in skeletal muscle of elite cyclists is associated with low mRNA expression levels

Myoglobin is essential for oxygen transport to the muscle fibers. However, measurements of myoglobin (Mb) protein concentrations within individual human muscle fibers are scarce. Recent observations have revealed surprisingly low Mb concentrations in elite cyclists, however it remains unclear whether this relates to Mb translation, transcription and/or myonuclear content. The aim was to compare Mb concentration, Mb messenger RNA (mRNA) expression levels and myonuclear content within muscle fibers of these elite cyclists with those of physically-active controls. Muscle biopsies were obtained from m. vastus lateralis in 29 cyclists and 20 physically-active subjects. Mb concentration was determined by peroxidase staining for both type I and type II fibers, Mb mRNA expression level was determined by quantitative PCR and myonuclear domain size (MDS) was obtained by immunofluorescence staining. Average Mb concentrations (mean ± SD: 0.38 ± 0.04 mM vs. 0.48 ± 0.19 mM; P = 0.014) and Mb mRNA expression levels (0.067 ± 0.019 vs. 0.088 ± 0.027; P = 0.002) were lower in cyclists compared to controls. In contrast, MDS and total RNA per mg muscle were not different between groups. Interestingly, in cyclists compared to controls, Mb concentration was only lower for type I fibers (P < 0.001), but not for type II fibers (P > 0.05). In conclusion, the lower Mb concentration in muscle fibers of elite cyclists is partly explained by lower Mb mRNA expression levels per myonucleus and not by a lower myonuclear content. It remains to be determined whether cyclists may benefit from strategies that upregulate Mb mRNA expression levels, particularly in type I fibers, to enhance their oxygen supply.

Sarcoplasmic model to study the effects of high-pressure processing on beef color

High-pressure processing (HPP) negatively impacts fresh meat color. The objective of the study was to use a sarcoplasmic (meat extract) model to better understand the effects of HPP on meat color. Sarcoplasm was extracted at pHs of 5.6, 6.0, or 6.4 and fractioned based on centrifugation speed at 0, 3500 g, and 15,000 g for 5 min. The extracts were processed using a commercial HPP unit at 300 MPa, 450 MPa, and 600 MPa, along with a non-pressurized control. Myoglobin concentration decreased (P < 0.05) with increased HPP levels. Sarcoplasm treated with 300 MPa had the greatest oxymyoglobin content (P < 0.05) compared with the non-pressurized control and other HPP levels. Deoxymyoglobin and metmyoglobin content were greater at 600 MPa compared with non-pressurized control and other HPP levels. In summary, higher pH and lower pressure can improve redness of sarcoplasm.

Association between preoperative serum myoglobin and acute kidney injury after Stanford Type A aortic dissection surgery

BackgroundAcute kidney injury (AKI) is a common complication after Type A aortic dissection (TAAD) surgery, and it is associated with poor outcomes. The nephrotoxic effect of myoglobin was established, but its correlation with AKI following TAAD repair still lacks sufficient evidence. We clarified the correlation between preoperative serum myoglobin (pre-sMyo) concentrations and AKI after TAAD surgery. MethodA retrospective analysis was performed on the perioperative data of 382 patients treated with TAAD surgery at Beijing Anzhen Hospital. AKI was defined and classified according to the criteria established by the Kidney Disease: Improving Global Outcomes Acute Kidney Injury Work Group. We attempted to determine the correlation between pre-sMyo concentrations and postoperative AKI. ResultsThe incidences of Stage 1, 2, and 3 AKI were 37.3 % (57/153), 23.5 % (36/153), and 39.2 % (60/153), respectively. The pre-sMyo concentrations of the AKI group were significantly increased than the non-AKI group [43.1 (21.4, 107.5) vs 26.4 (18.0, 37.2), P < 0.001]. Pre-sMyo concentrations have a linear correlation with preoperative renal function-related indicators. The multivariable logistic regression analysis showed that Ln (pre-sMyo) was an independent risk factor for AKI. When the pre-sMyo concentration was at the fourth quartile [109.3 (64.8, 213.4) ng/ml], the risk of developing any-stage and severe AKI was significantly increased (OR = 4.333, 95 % CI: 2.364–7.943, P < 0.001; OR = 3.862, 95 %, CI: 2.011–7.419, P < 0.001). This difference persisted after adjustment (OR = 3.830, 95 % CI: 1.848–7.936, P < 0.001; OR = 2.330, 95 % CI: 1.045–5.199, P = 0.039). Furthermore, pre-sMyo concentrations were not affected by lower limb malperfusion, myocardial malperfusion, and cardiac tamponade. ConclusionsIncreased pre-sMyo concentrations correlated with postoperative AKI in TAAD, which may increase the risk of developing any-stage AKI and severe AKI after TAAD surgery.

Myoglobinemia, Peripheral Arterial Disease, and Patient Mortality.

Peripheral arterial disease (PAD) causes leg muscle damage due to inadequate perfusion and increases cardiovascular events and mortality 2- to 3-fold. It is unclear if PAD is a biomarker for high-risk cardiovascular disease or if skeletal muscle injury harms arterial health. The objective of this work is to test if serum myoglobin levels (myoglobinemia) are a marker of PAD, and if so, whether myoglobin impairs vascular health. Patient blood samples were collected from PAD and control (no PAD) patients and interrogated for myoglobin concentrations and nitric oxide bioavailability. Patient mortality over time was captured from the medical record. Myoglobin activity was tested on endothelial cells and arterial function. Myoglobin is a biomarker for symptomatic PAD and was inversely related to nitric oxide bioavailability; 200 ng/mL myoglobin in vitro increased endothelial cell permeability in vitro and decreased nitrate bioavailability. Ex vivo, 100 ng/mL myoglobin increased vascular tone in naive murine aortas approximately 1.5 times, impairing absolute vessel relaxation. In vivo, we demonstrated that myoglobinemia caused impaired flow-mediated dilation in a porcine model. Patients presenting with myoglobin levels of 100 ng/mL or greater had significantly more deaths than those with myoglobin levels of less than 100 ng/mL. Using a combination of patient data, in vitro, ex vivo, and in vivo testing, we found that myoglobin is a biomarker for symptomatic PAD and a potent regulator of arterial health that can increase vascular tone, increase vascular permeability, and cause endothelial dysfunction, all of which may contribute to the vulnerability of PAD patients to cardiovascular events and death.

Highly Sensitive and Specific Detection of Myoglobin in the Urine Based on Enhanced Photothermal Effect

Acute myocardial infarction can be diagnosed by measurement of myoglobin concentration in urine. In this article, a label-free sensor is proposed based on the photothermal effect of biomolecules, which is used for the immediate detection of myoglobin concentration in urine. The sensor was fabricated by a tapered microfiber (TMF) coated with the ultraviolet-curable polymer (UVCP) that has a high thermo-optical coefficient. The photothermal signal of biomolecules is only related to their selective absorption, while the scattering and reflection losses do not generate the photothermal signal. Therefore, specific identification could be realized by detecting the photothermal signal of myoglobin biomolecules. The results showed that the UVCP could enhance the detection sensitivity of photothermal signal due to the high thermo-optic coefficient. The sensitivity of the device is −267.652 nm/(mg/mL) in the concentration range of 0.0001–0.10 mg/mL, the limit of detection (LOD) is 74.7 ng/mL, and the response time is only 30 s. It can meet the demand for detecting the myoglobin concentrations in the urine analysis of related diseases, which has potential applications in the early diagnosis and quantitative analysis of conditions.

The effectiveness of various approaches to the use of renal replacement therapy in the treatment of toxic rhabdomyolysis complicated by acute kidney injury

BACKGROUND. 60 % of cases of acute poisoning are complicated by the occurrence of rhabdomyolysis . The most common and dangerous complication of rhabdomyolysis is acute kidney injury (AKI), which increases mortality by up to 10 %. One of the most promising directions of pathogenetic therapy of rhabdomyolysis complicated by AKI is extracorporeal removal of myoglobin and other factors of endogenous intoxication from the systemic bloodstream . THE AIM: to improve the results of treatment of patients with toxic rhabdomyolysis complicated by acute kidney injury by applying the most effective tactics of renal replacement therapy . PATIENTS AND METHODS. The prospective study included 81 patients with toxic rhabdomyolysis complicated by AKI. In the first group , standard basic intensive therapy was performed ; in the second group , hemodiafiltration was performed at an early stage of AKI, in the third group , early application of hemodiafiltration with selective hemosorption was performed . The analysis of laboratory parameters of rhabdomyolysis , renal damage , as well as the outcomes of treatment of patients in groups was carried out . RESULTS. Early use of renal replacement therapy (RRT) increased the severity of reduction of myoglobin concentrations in blood and KIM-1 in urine during the first week of treatment from 26.3 % to 73.4 % and from 76.1 % to 96.8 %, respectively . The inclusion of RRT with selective hemosorption in the intensive therapy at an early stage of AKI allowed to increase these indicators to 88.0 % and 99.0 %, respectively . The most effective method is the use of a combination of RRT with selective hemosorption , which allows to increase the rate of recovery of kidney function and reduce the duration of the necessary use of RRT from 15 to 6 days , as well as to reduce hospital mortality from 14.3 % to 6.9 %.

Priming exercise accelerates oxygen uptake kinetics during high-intensity cycle exercise in middle-aged individuals with type 2 diabetes.

Background: The primary phase time constant of pulmonary oxygen uptake kinetics ( τ p) during submaximal efforts is longer in middle-aged people with type 2 diabetes (T2D), partly due to limitations in oxygen supply to active muscles. This study examined if a high-intensity "priming" exercise (PE) would speed τ p during a subsequent high-intensity cycling exercise in T2D due to enhanced oxygen delivery. Methods: Eleven (4 women) middle-aged individuals with type 2 diabetes and 11 (4 women) non-diabetic controls completed four separate cycling bouts each starting at an 'unloaded' baseline of 10W and transitioning to a high-intensity constant-load. Two of the four cycling bouts were preceded by priming exercise. The dynamics of pulmonary and muscle deoxygenation (i.e. deoxygenated haemoglobin and myoglobin concentration [HHb + Mb]), were calculated from breath-by-breath and near-infrared spectroscopy data at the vastus lateralis, respectively. Results: At baseline τ p, was slower (p < 0.001) in the type 2 diabetes group (48 ± 6s) compared to the control group (34 ± 2s) but priming exercise significantly reduced τ p (p < 0.001) in type 2 diabetes (32 ± 6s) so that post priming exercise it was not different compared with controls (34 ± 3s). Priming exercise reduced the amplitude of the slow component (As) in both groups (type 2 diabetes: 0.26 ± 0.11 to 0.16 ± 0.07L/min; control: 0.33 ± 0.13 to 0.25 ± 0.14L/min, p < 0.001), while [HHb + Mb] kinetics remained unchanged. Conclusion: These results suggest that in middle-aged men and women with T2D, PE speeds τ p likely by a better matching of O2 delivery to utilisation and reduces the As during a subsequent high-intensity exercise.

Production system influences color stability and lipid oxidation in gluteus medius muscle.

We aimed to evaluate the color and oxidative stability of beef gluteus medius (GM) from cattle raised in organic and non-organic production systems. The GM samples (n = 10) were obtained from organic (ORG; n = 5) or non-organic (NORG; n = 5) beef samples, sliced into 2.54-cm steaks, packaged in aerobic conditions, and stored for nine days at 4°C. ORG and NORG steaks were compared regarding myoglobin concentration, pH, instrumental color, delta E (ΔE), metmyoglobin reducing activity (MRA), and lipid oxidation on days 0, 5, and 9. Feeding system did not influence (p>0.05) the myoglobin concentration. ORG steaks exhibited greater (p<0.05) meat pH, yellowness, and MRA, whereas NORG steaks exhibited greater (p<0.05) redness, chroma, R630/580, delta E, and lipid oxidation. ORG and NORG steaks exhibited similar (p>0.05) lightness and hue angle. During storage, ORG and NORG exhibited an increase in muscle pH, hue angle, and lipid oxidation; and a decrease (p<0.05) in redness, yellowness, chroma, and color stability (R630/580). Both samples exhibited a stable (p>0.05) pattern for lightness and MRA. Therefore, the production system can affect beef color and lipid stability during storage.

Circulating microRNA levels after exercise-induced muscle damage and the repeated bout effect.

The neuromuscular system can quickly adapt to exercise-induced muscle damage (EIMD), such that it is less affected by subsequent damaging exercise, a phenomenon known as the repeated bout effect (RBE). Circulating muscle-specific microRNAs (myomiRs) may be able to potentially predict the long-lasting maximal voluntary contraction (MVC) torque deficit (>24 h), an indicator of EIMD. We aimed to investigate: 1) how plasma myomiR levels are modified by the RBE and 2) whether plasma myomiRs can predict the long-lasting MVC torque deficit. Nineteen participants performed two identical bouts of loaded downhill walking separated by 2 wk. MVC torque, creatine kinase (CK) activity, myoglobin (Mb) concentration, and myomiR levels were measured before and up to 48 h after exercise. Correlation and multiple regression analyses were performed to assess the ability of these markers to predict the largest MVC torque loss beyond 24 h postexercise. Similar to MVC torque, CK activity, and the Mb concentration, the relative abundance of certain myomiRs (hsa-miR-1-3p, and hsa-miR-133a-3p) was less affected after the second bout of exercise relative to the first bout. The CK activity, Mb concentration, and level of several myomiRs (hsa-miR-1-3p, hsa-miR-133a-3p, and hsa-miR-206) correlated with long-lasting MVC torque loss. Multiple regression showed that the best combination of markers to predict the long-lasting deficit of MVC torque included several myomiRs, Mb, and CK. Certain myomiR levels increased less after exercise bout 2 than after exercise bout 1, indicating the presence of the RBE. The measurement of myomiR levels in combination with Mb concentrations and CK activity could improve the prediction of the long-lasting MVC torque deficit.NEW & NOTEWORTHY The present study is the first to show that plasma muscle-specific microRNA (myomiR) levels can be modified by the repeated bout effect, as their levels increased less after the second exercise bout relative to the first. This study is also the first to suggest that myomiR levels could be used to partially predict maximal voluntary contraction torque loss at 24 h postexercise (i.e., the magnitude of exercise-induced muscle damage). Interestingly, the combined measurement of certain myomiR levels with those of myoglobin and creatine kinase improved the predictive value.

Effect of a 6-Week Cycle of Nordic Walking Training on Vitamin 25(OH)D3, Calcium-Phosphate Metabolism and Muscle Damage in Multiple Myeloma Patients-Randomized Controlled Trial.

Multiple myeloma (MM) is a hematological malignancy affecting older adults. One of the most common myeloma-defining events is the development of symptomatic lytic bone disease. The serum concentrations of calcium (Ca), inorganic phosphorus (P), and vitamin 25(OH)D3 in the serum reflect bone metabolism. An enzyme lactate dehydrogenase (LDH) is a marker of muscle damage, but its serum activity also has an important prognostic value in MM. Myoglobin (Mb) is a small protein present in muscles; its serum level increases when myocytes are damaged. In this study, the impact of a 6-week Nordic walking (NW) exercise program on blood parameters related to calcium-phosphate metabolism and damage of skeletal muscles was assessed. A total of 33 patients with MM in the remission stage, without cytostatic treatment, were allocated and randomly assigned to one of two groups: 17 in the training group (NW) and 16 in the control group (CG). All patients were supplemented per os with vitamin D3 and calcium carbonate daily and received zoledronic acid every 4 weeks (intravenous). Nordic walking training sessions took place 3 times a week for 6 weeks, 1 h each. Blood samples were drawn before and after the 6 weeks of training sessions to assess the serum concentrations of vitamin 25(OH)D3, P, Ca, Mb, and LDH. Patients from the NW group showed a statistically significant decrease in mean serum myoglobin concentration (p = 0.018) and an increase in 25(OH)D3 (p &lt; 0.001) and total Ca (p = 0.001) concentrations. There were no statistically significant changes in the results obtained in CG. Between groups, after 6 weeks, Mb serum concentration was significantly lower in NW (p = 0.041), and 25(OH)D3 was higher (p &lt; 0.001) compared to CG. There was a correlation between the changes in myoglobin, phosphorus, 25(OH)D3, and Ca concentrations after 6 weeks. NW training is a safe and beneficial form of physical exercise for patients with MM without inducing muscle damage. NW performed outside improves serum vitamin 25(OH)D3 concentration.

Rhabdomyolysis Associated with Recent SARS-COV-2 Infection in a Patient with Carnitine Palmitoyltransferase II Deficiency.

Carnitine palmitoyltransferase II deficiency (CPT II) is an autosomal recessive inherited disorder of long-chain fatty acid oxidation in the mitochondrial matrix, resulting in an inability to utilize fat for energy in cells. The most frequent myopathic form occurs in young adults and is associated with recurrent episodes of exercise-induced rhabdomyolysis. The myopathic form is caused by the Ser113Leu mutation of the CPT II gene. Rarely, massive rhabdomyolysis could be complicated by acute kidney injury (AKI), cardiomyopathy, and respiratory insufficiency. We present a case of an 18-year old male with myalgia, muscular weakness, and dark-colored urine after prolonged exercise and a recent mildSARS-CoV-2infection. Massive rhabdomyolysis was diagnosed with markedly increased serum concentrations of myoglobin and creatine kinase, with normal kidney function. The patient experienced two similar episodes in the years 2017 and 2018, with rhabdomyolysis and AKI treated with hemodialysis. After excluding autoimmune and infectious diseases as causes of recurrent rhabdomyolysis, the patient was genetically tested and Ser113Leu mutation of the CPT II gene was confirmed. When a patient presents with myalgia and dark-colored urine triggered by minor physical activities, genetic testing for possible CPT II deficiency should be initiated. TheSARS-CoV-2infection could be a factor that triggers the occurrence of rhabdomyolysis and aggravates the severity of the attack in patients with CPT II deficiency.