Biochemical markers of muscular damage

Effect of Ramadan intermittent fasting on cognitive, physical and biochemical responses to strenuous short-term exercises in elite young female handball players

The present study aimed to assess the effect of Ramadan intermittent fasting (RF) on cognitive and physical performance and biochemical responses to specific exercises in elite young female handball players. Twelve athletes participated in three experimental sessions: one week before Ramadan (BR), during the first week of Ramadan (FWR) and during the last week of Ramadan (LWR). The present crossover study was carried out in Tunisia during the 2013 Ramadan month lasting from 9 July to 7 august. During each session, a battery of tests was performed as follow: Hooper index, vigilance test (VT), Epworth sleepiness scale (ESS), five jump test (5-JT), modified agility T-test (MAT), maximal standing ball-throw velocity test (MSBVT) and Running-based Anaerobic Sprint (RAST) Test. Rating of perceived exertion (RPE) was recorded immediately after the RAST. Blood samples were collected before and after exercises during each session. The results showed that ESS scores were higher during LWR than BR (p < 0.05). Moreover, MSBVT time decreased (p < 0.05) during LWR, therefore performance enhanced. The power of three final sprints from the RAST decreased significantly only during LWR compared to BR (p < 0.05). RAST fatigue index and RPE scores were higher during LWR more than BR (p < 0.05). The results showed also that hematological measures (i.e., red blood cells, hemoglobin and hematocrit), plasma osmolarity and energetic markers were unaffected by RF. Biomarkers of muscle damage were higher after the RAST only during LWR compared to BR (p < 0.01 for all). In conclusion, RF increased ESS and decreased RAST performances associated with higher muscle damage and fatigue, especially at LWR. These previous alterations could be attributed to disturbances of sleep and circadian rhythms rather than nutritional deficiency or dehydratation.

Beyond the mechanical lens: Systemic inflammatory responses to repetitive lifting under varying loads and frequencies

OBJECTIVE

Currently, low back disorder (LBD) research focuses primarily on mechanical variables to assess whether task demands exceed tissue capacity; however, it is important to assess how other nonmechanical variables affect tissue capacity in a time-dependent manner. The current investigation sought to explore physiological responses to an acute lifting task, as lifting has been implicated as a risk factor in the development of LBDs.

METHODS

Twelve participants completed two sessions of 2 h of repetitive symmetrical lifting from floor to knuckle height under two conditions, matched for total external work (Low Force High Repetition (LFHR) and High Force Low Repetition (HFLR)). Full-body kinematics and ground reaction forces were measured throughout. Interleukin 6 (IL-6) and interleukin 8 (IL-8), markers of systemic inflammation, were assessed from blood sampling at Baseline, 0, 4 and 24 h post-lifting on both days. Dual x-ray absorptiometry (DEXA) scans were also performed on participants to quantify body composition.

RESULTS

Significant load (HFLR and LFHR) * time (Baseline, 0, 4, 24 h) interaction effects were found for both IL-6 and IL-8, where the LFHR condition resulted in greater responses at 0 and 4 h post-lifting.

CONCLUSIONS

This was the first study of its kind to concurrently measure peak and cumulative spinal moments and their relationship to systemic inflammation in both sexes, while strictly controlling for confounding variables (e.g. physical activity, caloric intake, body composition, etc.). Greater levels of IL-6 and IL-8 were seen in the LFHR condition, likely due to the greater cumulative spinal moments in this condition.

Changes in Urinary Titin Fragment in Response to Different Types of Dynamic Eccentric Exercises

The urinary level of the titin fragment has been considered a non-invasive and sensitive biomarker for muscle damage in clinical cases. However, there is little evidence regarding changes in the urinary titin fragment in response to exercise-induced muscle damage. In this study, we aimed to investigate whether the urinary titin fragment reflects the magnitude of muscle damage induced by two lower-limb eccentric exercises. In this study, healthy young male subjects performed drop jump (n=9) and eccentric ergometer exercise (n=9). Blood and urine samples were collected at various time points before and after the exercises. Although perceived muscle soreness assessed by sit-to-stand tasks was increased at 24 h and 48 h after both drop jump and the eccentric ergometer exercise groups, the pressure pain threshold was not changed. Changes of the urinary titin fragment, plasma myomesin 3 fragments, creatine kinase (CK), and myoglobin (Mb) after the eccentric exercises were increased but not statistically significant. Meanwhile, we found that the changes in the urinary titin fragment levels in response to both drop jump and the eccentric ergometer exercise were correlated with those of plasma CK and Mb levels. These results provide evidence that the urinary titin fragment level is a non-invasive biomarker reflecting the magnitude of eccentric exercise-induced muscle damage.

Diagnosis and prognosis for exercise-induced muscle injuries: from conventional imaging to emerging point-of-care testing

With the development of modern society, we have witnessed a significant increase of people who join in sport exercises, which also brings significantly increasing exercise-induced muscle injuries, resulting in reduction and even cessation of participation in sports and physical activities. Although severely injured muscles can hardly realize full functional restoration, skeletal muscles subjected to minor muscle injuries (e.g., tears, lacerations, and contusions) hold remarkable regeneration capacity to be healed without therapeutic interventions. However, delayed diagnosis or inappropriate prognosis will cause exacerbation of the injuries. Therefore, timely diagnosis and prognosis of muscle injuries is important to the recovery of injured muscles. Here, in this review, we discuss the definition and classification of exercise-induced muscle injuries, and then analyze their underlying mechanism. Subsequently, we provide detailed introductions to both conventional and emerging techniques for evaluation of exercise-induced muscle injuries with focus on emerging portable and wearable devices for point-of-care testing (POCT). Finally, we point out existing challenges and prospects in this field. We envision that an integrated system that combines physiological and biochemical analyses is anticipated to be realized in the future for assessing muscle injuries.

Tandem Mass Tag-Based Serum Proteome Profiling for Biomarker Discovery in Young Duchenne Muscular Dystrophy Boys

Blood-accessible molecular biomarkers are becoming highly attractive tools to assess disease progression and response to therapies in Duchenne muscular dystrophy (DMD) especially in very young patients for whom other outcome measures remain subjective and challenging. In this study, we have standardized a highly specific and reproducible multiplexing mass spectrometry method using the tandem mass tag (TMT) strategy in combination with depletion of abundant proteins from serum and high-pH reversed-phase peptide fractionation. Differential proteome profiling of 4 year-old DMD boys (n = 9) and age-matched healthy controls (n = 9) identified 38 elevated and 50 decreased serum proteins (adjusted P < 0.05, FDR <0.05) in the DMD group relative to the healthy control group. As expected, we confirmed previously reported biomarkers but also identified novel biomarkers. These included novel muscle injury-associated biomarkers such as telethonin, smoothelin-like protein 1, cofilin-1, and plectin, additional muscle-specific enzymes such as UTP-glucose-1-phosphate uridylyltransferase, aspartate aminotransferase, pyruvate kinase PKM, lactotransferrin, tissue alpha-l-fucosidase, pantetheinase, and ficolin-1, and some pro-inflammatory and cell adhesion-associated biomarkers such as leukosialin, macrophage receptor MARCO, vitronectin, galectin-3-binding protein, and ProSAAS. The workflow including serum depletion, sample processing, and mass spectrometry analysis was found to be reproducible and stable over time with CV < 20%. Furthermore, the method was found to be superior in terms of specificity compared to other multiplexing affinity-based methods. These findings demonstrate the specificity and reliability of TMT-based mass spectrometry methods in detection and identification of serum biomarkers in presymptomatic young DMD patients.

Evaluation of the Adverse Effects of Chronic Exposure to Donepezil (An Acetylcholinesterase Inhibitor) in Adult Zebrafish by Behavioral and Biochemical Assessments

Donepezil (DPZ) is an acetylcholinesterase inhibitor used for the clinical treatment of mild cognitive impairment. However, DPZ has been reported to have adverse effects, including causing abnormal cardiac rhythm, insomnia, vomiting, and muscle cramps. However, the existence of these effects in subjects without Dementia is unknown. In this study, we use zebrafish to conduct a deeper analysis of the potential adverse effects of DPZ on the short-term memory and behaviors of normal zebrafish by performing multiple behavioral and biochemical assays. Adult zebrafish were exposed to 1 ppm and 2.5 ppm of DPZ. From the results, DPZ caused a slight improvement in the short-term memory of zebrafish and induced significant elevation in aggressiveness, while the novel tank and shoaling tests revealed anxiolytic-like behavior to be caused by DPZ. Furthermore, zebrafish circadian locomotor activity displayed a higher reduction of locomotion and abnormal movement orientation in both low- and high-dose groups, compared to the control group. Biomarker assays revealed that these alterations were associated with an elevation of oxytocin and a reduction of cortisol levels in the brain. Moreover, the significant increases in reactive oxygen species (ROS) and malondialdehyde (MDA) levels in muscle tissue suggest DPZ exposure induced muscle tissue oxidative stress and muscle weakness, which may underlie the locomotor activity impairment. In conclusion, we show, for the first time, that chronic waterborne exposure to DPZ can severely induce adverse effects on normal zebrafish in a dose-dependent manner. These unexpected adverse effects on behavioral alteration should be carefully addressed in future studies considering DPZ conducted on zebrafish or other animals.

Supercapsular Percutaneously Assisted total hip arthroplasty versus lateral approach in Total Hip Replacement. A prospective comparative study

Background

Supercapsular Percutaneously Assisted total hip arthroplasty (SuperPATH approach) is a relatively new minimal invasive approach which has been associated with encouraging postoperative outcomes. The aim of this study is to compare the minimal invasive (MIS) SuperPATHapproach with the standard modified Hardinge approach at the base of muscle damage due to serum markers, functional results and other perioperative and postoperative data.

Material and methods

Forty eight (48) consecutive patients undergone primary total hip arthroplasty (THA) by the same surgeon (GD), were enrolled in our study. From this study population, the modified Hardinge approach was performed in 23 patients and the SuperPATH approach was performed in 25 patients. Soft tissue impairment was studied based on three representative markers, C-reactive-protein (CRP) and two enzymes, creatine kinase (CK) and lactate dehydrogenase (LDH). We measured these markers 10 min after surgery, on 1st and 2nd postoperative day. The levels of the perceived pain were evaluated according to the Visual Analog Scale/Numerical Rating Scale (VAS/NRS) score which was registered 6 h, 12 h, 1 day and 2 days postoperatively. The functional and clinical evaluation of the patients was achieved with Harris Hip Score (HHS), Charnley's Hip score, EuroQol (EQ-5D)-(EQ-100), Patient Health Questionnaire (PHQ-9) and neuropathic pain questionnaire (DN-4) 6 months and 1 year postoperatively. The rest of the collected data included patient's age, gender, body mass index (BMI), other comorbitities, the American Society of Anesthiologists score (ASA), Charlson Index score, the pre-operative diagnosis, implant positioning through radiographic evaluation, the type of anesthesia, the days of hospitalization, the operating time, incision length, blood loss and blood transfusion requirements and complication rates.

Results

SuperPATH approach was related with statistically considerable lower levels of CRP at 10 min (p = 0,001) and at 24 h (p = 0,047) postoperatively, as well as lower LDH levels in all time points postoperatively. It was also associated with shorter incision length (p < 0.001), longer operating time (p < 0.001), higher mean cup inclination p < 0.001, decreased postoperative pain levels the first 6 and 12 h (p < 0.001) and relatively better clinical and functional results 6 months after surgery, but not at 12 months.

Conclusion

Our study revealed some advantages in favor of the SuperPATH approach comparing with the standard modified Hardinge approach, mainly in terms of less muscle damage and less perceived pain postoperatively. More research is required in order to further elucidate its efficacy.

Methods for Regulating and Monitoring Resistance Training

Individualisation can improve resistance training prescription. This is accomplished via monitoring or autoregulating training. Autoregulation adjusts variables at an individualised pace per performance, readiness, or recovery. Many autoregulation and monitoring methods exist; therefore, this review’s objective was to examine approaches intended to optimise adaptation. Up to July 2019, PubMed, Medline, SPORTDiscus, Scopus and CINAHL were searched. Only studies on methods of athlete monitoring useful for resistance-training regulation, or autoregulated training methods were included. Eleven monitoring and regulation themes emerged across 90 studies. Some physiological, performance, and perceptual measures correlated strongly (r ≥ 0.68) with resistance training performance. Testosterone, cortisol, catecholamines, cell-free DNA, jump height, throwing distance, barbell velocity, isometric and dynamic peak force, maximal voluntary isometric contractions, and sessional, repetitions in reserve-(RIR) based, and post-set Borg-scale ratings of perceived exertion (RPE) were strongly associated with training performance, respectively. Despite strong correlations, many physiological and performance methods are logistically restrictive or limited to lab-settings, such as blood markers, electromyography or kinetic measurements. Some practical performance tests such as jump height or throw distance may be useful, low-risk stand-ins for maximal strength tests. Performance-based individualisation of load progression, flexible training configurations, and intensity and volume modifications based on velocity and RIR-based RPE scores are practical, reliable and show preliminary utility for enhancing performance.

Coronavirus Disease 2019-Induced Rhabdomyolysis

Rhabdomyolysis is caused by necrosis of muscles and leakage of intracellular contents into blood circulation. It is most commonly caused by trauma, crush injuries, drugs, toxins, immobilization, compartment syndrome, prolonged surgical procedures, and less likely by infections. Infection-related rhabdomyolysis is rare, but not uncommon, and is seen in both viral and bacterial infections. Extrapulmonary manifestations of coronavirus disease 2019 (COVID-19) include thrombotic like pulmonary emboli, acute cerebrovascular accident, myocardial infarction, cardiac arrhythmias, liver injury, gangrene, diarrhea, acute renal failure, and so on. We here describe a case of COVID-19-induced rhabdomyolysis in a 19-year-old Hispanic male presenting with muscle aches, fatigue, fevers, and no pulmonary symptoms. 

Intra-Individual and Seasonal Variation of Selected Biomarkers for Internal Load Monitoring in U-19 Soccer Players

The aim of this study was to investigate inter-day and -week as well as intra- and inter-individual variation of selected biomarkers in high-performance youth soccer players to assist practitioners interpreting player's internal load to counteract underperformance and unwanted health risks. Eleven male youth soccer players were tested multiple times during two 3-week periods at midpoint (3-wk_mid) and at the end (3-wk_end) of the first half of a German under-19 1. Bundesliga season. The levels of creatine kinase (CK), urea, and C-reactive protein (CRP) were measured during 3-wk_mid and 3-wk_end each Monday, Wednesday, and Friday. In 3-wk_mid the CK median was 14% higher (241 vs. 212 U/L) compared to 3-wk_end (P = 0.26, ES = 0.16). Overall, the medians of CK, urea (P = 0.59, ES = 0.08), and CRP (P = 0.56, ES = 0.10) during 3-wk_mid did not differ to the values of 3-wk_end. Daily coefficient of variations (CVs) ranged from 22 to 71% (CK), 17 to 37% (urea), and 9 to 164% (CRP). Individual medians ranged from 101 to 350 U/L (CK), 23 to 50 mg/dL (urea), and 0.6 to 1.1 mg/L (CRP). High intra-individual variability was demonstrated by large intra-individual CVs (medians: CK 50%, urea 18%, and CRP 45%). Our data show (i) large inter-day and inter-week variability of all biomarkers, depending on the external load and (ii) considerable inter- and intra-individual parameter variations. Creatine kinase concentrations could sensitively reflect soccer-specific loads during the season.

Incidence and risks for surgical site infection after closed tibial plateau fractures in adults treated by open reduction and internal fixation: a prospective study

Background

Surgical site infection (SSI) was the most common complication of tibial plateau fracture after open reduction and internal fixation (ORIF). Severe infections even required repeat surgeries, which would cause serious psychological harm to patients and increased the economic burden of treatment. In order to identify the characteristics of the SSI and to avoid the occurrence of SSI, we conducted a prospective study to investigate the incidence and independent risk factors of SSI after ORIF for closed tibial plateau fractures in adults.

Methods

This study was performed at a first-level trauma center. From October 2014 to December 2018, the study subjects were adult patients with closed fractures of the tibial plateau, all of whom underwent open reduction and internal fixation (ORIF) treatment. Finally, a total of 1108 patients were followed up. We collected patient demographics information, surgery-related variables, and indexes from preoperative laboratory examinations. Univariate and multivariate logistic analysis models were used to investigate the potential risk factors.

Results

Twenty-five patients (2.3%, 25/1108) developed SSI. A total of 15 of 25 infections (60.0%) were due to Staphylococcus aureus and 3 (12.0%) were due to MRSA. Independent risk factors of SSI identified by multivariate logistic analysis model were bone grafting: autograft (OR 6.38; 95% CI 2.155–18.886; p = 0.001) and allograft (OR 3.215; 95% CI 1.009–10.247; p = 0.048), fracture type (Schartzker V–VI) (OR 8.129; 95% CI 2.961–22.319; p < 0.001), aspartate aminotransferase (>40 U/L) (OR 5.500; 95% CI 2.191–13.807; p < 0.001), white blood cell (>10*10⁹/L) (OR 2.498; 95% CI 1.025–6.092; p = 0.044), and anion gap (>16 mmol/L) (OR 8.194; 95% CI 1.101–60.980).

Conclusions

We should pay enough attention to patients who carried one or more of these factors at admission and adopt more reasonable treatment strategies to reduce or avoid the occurrence of SSI.

Response of Muscle Damage Markers to an Accentuated Eccentric Training Protocol: Do Serum and Saliva Measurements Agree?

González-Hernández, JM, Jiménez-Reyes, P, Cerón, JJ, Tvarijonaviciute, A, Llorente-Canterano, FJ, Martínez-Aranda, LM, and García-Ramos, A. Response of muscle damage markers to an accentuated eccentric training protocol: do serum and saliva measurements agree? J Strength Cond Res XX(X): 000-000, 2020-This study aimed (a) to examine the acute and delayed responses of 3 muscle damage biomarkers: creatine kinase (CK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) to an accentuated eccentric training protocol in serum, and (b) to explore the changes of these biomarkers in saliva and compare them with serum. Sixteen resistance-trained university students (10 men [age = 26.6 ± 4.8 years, full squat one repetition maximum [1RM] = 103.4 ± 14.4 kg] and 6 women [age = 22.7 ± 1.4 years, full squat estimated 1RM = 68.3 ± 10.5 kg]) completed an accentuated eccentric strength training protocol with the full squat exercise consisting of 8 sets of 10 repetitions against the 120% estimated 1RM load with 5 minutes of interset rest. The activity of muscle damage biomarkers (CK, AST, and LDH) was measured in serum and saliva before training (Pre), 24 hours after training (Post24), and 96 hours after training (Post96). In serum, lower values of the 3 muscle damage markers were observed at Pre compared to Post24 and Post96, whereas no significant differences were observed between Post24 and Post96 for any analyte. In saliva, there was a significant increase in men at Post96 compared with Pre in CK. The correlations between the measurements in serum and saliva ranged from trivial to small (r = -0.034 to 0.212). These results suggest that the measurement of muscle damage markers in serum and saliva do not provide the same information in the conditions of our study.

Effect of D-ribose supplementation on delayed onset muscle soreness induced by plyometric exercise in college students

Objective

Previous investigations suggest that appropriate nutritional interventions may reduce delayed onset muscle soreness (DOMS). This study examined the effect of D-ribose supplementation on DOMS induced by plyometric exercise.

Methods

For the purpose of inducing DOMS, 21 untrained male college students performed a lower-limb plyometric exercise session that involved 7 sets of 20 consecutive frog hops with 90-s of rest between each set. Muscle soreness was measured with a visual analogue scale 1-h before, 24-h after, and 48-h after exercise. Subjects were then randomly placed into the D-ribose group (DRIB, n = 11) and the placebo group (PLAC, n = 10) to assure equivalent BMI and muscle soreness. After a 14-d washout/recovery period, subjects performed the same exercise session, with DRIB ingesting a 200 ml solution containing 15 g D-ribose 1-h before, 1-h, 12-h, 24-h, and 36-h after exercise, and PLAC ingesting a calorically equivalent placebo of the same volume and taste containing sorbitol and β-cyclodextrin. Muscle soreness and isokinetic muscle strength were measured, and venous blood was assessed for markers of muscle damage and oxidative stress 1-h before, 24-h and 48-h after exercise.

Results

In DRIB, muscle soreness after 24-h and 48-h in the second exercise session were significantly lower (p < 0.01) than was experienced in the first exercise session. In the second exercise, blood-related markers of muscle soreness, including creatine kinase, lactate dehydrogenase (LDH), myoglobin and malondialdehyde (MDA) in DRIB after 24-h were lower in DRIB after 24-h than in PLAC (MDA, p < 0.05; rest outcomes, p < 0.01). In addition, LDH and MDA in DRIB were significantly lower (p < 0.01) after 24-h in DRIB than in PLAC. No difference was found in isokinetic muscle strength and oxidative stress markers, including superoxide dismutase and total antioxidant capacity, between DRIB and PLAC after 24-h and 48-h.

Conclusion

D-ribose supplementation reduces muscle soreness, improves recovery of muscle damage, and inhibits the formation of lipid peroxides. Young adult males performing plyometric exercise are likely to realize a DOMS reduction through consumption of D-ribose in 15 g/doses both before (1-h) and after (1-h, 12-h, 24-h, 36-h) exercise. These results suggest that appropriately timed consumption of D-ribose may induce a similar alleviation of exercise-induced DOMS in the general public.

Diagnosis and Management of Rhabdomyolysis in the Absence of Creatine Phosphokinase: A Medical Record Review

INTRODUCTION

Rhabdomyolysis is often encountered in austere environments where the diagnosis can be challenging due to the expense or unavailability of creatine phosphokinase (CPK) testing. CPK concentration ≥5,000 U/L has previously been found to be a sensitive marker for progression to renal failure. This study sought to propose a model utilizing an alternate biomarker to allow for the diagnosis and monitoring of clinically significant rhabdomyolysis in the absence of CPK.

MATERIALS AND METHODS

We performed a retrospective chart review of 77 patients admitted to a tertiary medical center with a primary diagnosis of rhabdomyolysis. A linear regression model with aspartate aminotransferase (AST) as the independent variable was developed and used to predict CPK ≥5,000 U/L on admission and CPK values on subsequent hospital days. The study was approved and monitored by the Institutional Review Board at Walter Reed National Military Medical Center.

RESULTS

Ln(AST) explained over 80% of the variance in ln(CPK) (adjusted R2 = 0.802). The diagnostic accuracy to predict CPK ≥5,000 U/L was high (AUC 0.959; 95% CI: 0.921-0.997, P < 0.001). A cut point of AST ≥110 U/L in our study population had a 97.1% sensitivity and an 85.7% specificity for the detection of a CPK value ≥5,000 U/L. The agreement between actual CPK and predicted CPK for subsequent days of hospitalization was fair with an intraclass correlation coefficient of 0.52 (95% CI: 0.38-0.63). The developed model based on day 1 data tended to overpredict CPK values on subsequent hospital days.

CONCLUSIONS

We propose a threshold concentration of AST that has an excellent sensitivity for detecting CPK concentration ≥5,000 U/L on day of admission in a patient population with a diagnosis of rhabdomyolysis. A formula with a fair ability to predict CPK levels based on AST concentrations on subsequent hospital days was also developed.

Improved Physical Performance and Decreased Muscular and Oxidative Damage With Postlunch Napping After Partial Sleep Deprivation in Athletes

PURPOSE

To investigate the effects of napping after partial sleep deprivation (PSD) on reaction time, mood, and biochemical response to repeated-sprint exercise in athletes.

METHODS

Nine male judokas performed 4 test sessions in a counterbalanced and randomized order. Participants accomplished 1 control session after a normal sleep night (NSN) and 3 after PSD with (1) no nap, (2) ∼20-min nap (N20), and (3) ∼90-min nap (N90) opportunities. Test sessions included the running-based anaerobic sprint test, reaction time, Hooper index, and Epworth Sleepiness Scale. Muscle-damage biomarkers and antioxidant status were evaluated before and after exercise.

RESULTS

PSD decreased maximum (P < .001, d = 1.12), mean (P < .001, d = 1.33), and minimum (P < .001, d = 1.15) powers compared with NSN. However, N20 and N90 enhanced maximum power compared with PSD (P < .05, d = 0.54; P < .001, d = 1.06, respectively). Minimum power and mean power increased only after N90 (P < .001, d = 1.63; P < .001, d = 1.16, respectively). Epworth Sleepiness Scale increased after PSD (P < .001, d = 0.86) and decreased after N20 (P < .001, d = 1.36) and N90 (P < .001, d = 2.07). N20 reduced multiple-choice reaction time (P < .001, d = 0.61). Despite performance decrement, PSD increased postexercise aspartate aminotransferase (P < .001, d = 4.16) and decreased glutathione peroxidase (P < .001, d = 4.02) compared with NSN. However, the highest performances after N90 were accompanied with lesser aspartate aminotransferase (P < .001, d = 1.74) and higher glutathione peroxidase (P < .001, d = 0.86) compared with PSD.

CONCLUSIONS

Napping could be preventive against performance degradation caused by sleep loss. A short nap opportunity could be more beneficial when the subsequent effort is brief and requires frequent decision making. However, a longer nap opportunity could be preventive against muscle and oxidative damage, even for higher performances.

Intermittent Hypoxic Exposure with High Dose of Arginine Impact on Circulating Mediators of Tissue Regeneration

Intermittent exposure to hypoxia (IHE) increases production of reactive oxygen and nitrogen species which, as signalling molecules, participate in tissue injury–repair–regeneration cascade. The process is also stimulated by arginine whose bioavailability is a limiting factor for NO synthesis. The effects of IHE in combination with arginine (Arg) intake on myogenesis and angiogenesis mediators were examined in a randomized and placebo-controlled trial. Blood samples were collected from 38 elite athletes on the 1st, 7th and 14th days during the training camp. The oral doses of arginine (2 × 6 g/day) and/or IHE using hypoxicator GO2Altitude (IHE and Arg/IHE) were applied. Serum NO and H₂O₂ concentrations increased significantly and were related to muscle damage (CK activity >900 IU/mL) in IHE and Arg/IHE compared to placebo. The changes in NO and H₂O₂ elevated the levels of circulating growth factors such as HGF, IHG-1, PDGF^BB, BDNF, VEGF and EPO. Modification of the lipid profile, especially reduced non-HDL, was an additional beneficial effect of hypoxic exposure with arginine intake. Intermittent hypoxic exposure combined with high-dose arginine intake was demonstrated to affect circulating mediators of injury–repair–regeneration. Therefore, a combination of IHE and arginine seems to be a potential therapeutic and non-pharmacological method to modulate the myogenesis and angiogenesis in elite athletes.

Case Report: A COVID-19 Patient Presenting with Mild Rhabdomyolysis

The news was reported from the Wuhan region of China about a novel corona virus in the end of 2019. After spreading around the world, a pandemic was declared by the WHO. Depending on the different involvement of the disease, the most common symptoms are fever, cough, and dyspnea. However, some indeterminate symptoms that make diagnosis difficult, such as myalgia and fatigue, can also be seen alone, without the typical clinical picture. We describe a patient with COVID-19 pneumonia, the only complaint of which is myalgia, and the first diagnosis is mild rhabdomyolysis. The patient had no evidence or history other than viral infection that could explain muscle pain and also increased level of muscle enzymes. When mild rhabdomyolysis lack of myoglobinuria and complications was diagnosed, treatment-related rhabdomyolysis was also avoided as no treatment related to COVID-19 was initiated yet. Apart from the typical symptoms leading to the typical diagnosis of COVID-19 at the first admission, SARS-CoV-2 related with rhabdomyolysis should also be kept in mind.

The usefulness of lactate dehydrogenase measurements in current oncological practice

One of the hallmarks of cancer cells is increased energy requirements associated with the higher rate of cellular proliferative activity. Metabolic changes in rapidly dividing cancer cells are closely associated with increased uptake of glucose and abnormal activity of lactate dehydrogenase (LDH), which regulates the processing of glucose to lactic acid. As serum LDH levels were found to be commonly increased in cancer patients and correlated with poor clinical outcome and resistance to therapy, the determination of LDH has become a standard supportive tool in diagnosing cancers or monitoring the effects of cancer treatment. The aim of this review is to summarize the current knowledge about methods and the practical utility for measuring both the total LDH and LDH isoenzymatic activities in the diagnosis, prognosis and prediction of cancer diseases.

Mechanisms Regulating Muscle Regeneration: Insights into the Interrelated and Time-Dependent Phases of Tissue Healing

Despite a massive body of knowledge which has been produced related to the mechanisms guiding muscle regeneration, great interest still moves the scientific community toward the study of different aspects of skeletal muscle homeostasis, plasticity, and regeneration. Indeed, the lack of effective therapies for several physiopathologic conditions suggests that a comprehensive knowledge of the different aspects of cellular behavior and molecular pathways, regulating each regenerative stage, has to be still devised. Hence, it is important to perform even more focused studies, taking the advantage of robust markers, reliable techniques, and reproducible protocols. Here, we provide an overview about the general aspects of muscle regeneration and discuss the different approaches to study the interrelated and time-dependent phases of muscle healing.

Effect of Body Fat Percentage on Muscle Damage Induced by High-Intensity Eccentric Exercise

This study aimed to investigate the impact of percent body fat (%BF) on muscle damage after high-intensity eccentric exercise. Thirty healthy male undergraduates (mean age: 22.0 ± 2 years, height: 176.9 ± 5 cm, weight: 75.8 ± 11.6 kg) participated in this study, and they were classified according to their %BF into a high %fat group (HFG, ≥20%, n = 15) and a low %fat group (LFG, ≤15%, n = 15). For eccentric exercise, two sets of 25 reps were performed on a modified preacher curl machine using the elbow flexor muscle. Maximal isometric strength, muscle soreness (passive and active), creatine kinase (CK), and myoglobin (Mb) were measured as indices of muscle damage. The data were analyzed with repeated measures ANOVA. The results show that there is a significant group–time interaction for both CK and Mb after eccentric exercise (p = 0.007, p = 0.015, respectively), with a greater increase in the HFG than in the LFG. However, there was no significant group–time interaction for maximal isometric strength and muscle soreness (passive and active) (p > 0.05). These results suggest that %BF is a factor that alters the muscle damage indices CK and Mb, which indicate membrane disruption, after eccentric exercise.

Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners

Background-exercise-induced muscle damage (EIMD) and internal exercise load are increased after competing in ultraendurance events such as mountain marathons. Adequate carbohydrate (CHO) intake during exercise optimizes athletic performance and could limit EIMD, reduce internal exercise load and, thus, improve recovery. Therefore, the aim of this study was to research into and compare the effects of high CHO intake (120 g/h) in terms of CHO intake recommendation (90 g/h) and regular CHO intake performed by ultraendurance athletes (60 g/h) during a mountain marathon, on exercise load and EIMD markers (creatine kinase (CK), lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), urea and creatinine). Materials and Methods-a randomized trial was carried out on 20 male elite runners who had previously undertaken nutritional and gut training, and who consumed different CHO dosages according to experimental (EXP-120 g/h), control (CON-90 g/h) and low CHO intake (LOW-60 g/h) groups during a ~4000 m cumulative slope mountain marathon. EIMD markers were analyzed before the race and 24 h afterwards. Internal exercise load was calculated based on rate of perceived exertion (RPE) during and after the marathon event. Results-internal exercise load during the mountain marathon was significantly lower (p = 0.019; η2p = 0.471) in EXP (3805 ± 281 AU) compared to LOW (4688 ± 705 AU) and CON (4692 ± 716 AU). Moreover, results revealed that the EXP group evidenced significantly lower CK (p = 0.019; η2p = 0.373), LDH (p < 0.001; η2p = 0.615) and GOT (p = 0.003; η2p = 0.500) values 24 h after the mountain marathon race compared to LOW and CON. Along these lines, EIMD and exercise load evidenced a close correlation (R = 0.742; p < 0.001). Conclusion: High CHO intake (120 g/h) during a mountain marathon could limit the EIMD observed by CK, LDH and GOT and internal exercise load compared to CHO ingestion of 60 and 90 g/h.

Effect of nocturnal melatonin intake on cellular damage and recovery from repeated sprint performance during an intensive training schedule

An optimal recovery between training sessions is of similar if not greater importance as the training content and program of the training, itself. One of the most used strategies for improving recovery is the ingestion of supplements. The present study aimed to evaluate the effect of 5 mg oral melatonin supplementation on the recovery from repeated sprint (RSA) of performance and biochemical responses (i.e. oxidative stress, leukocytosis cellular damage) after an intensive training camp (TC). Twenty soccer players performed an RSA test before and after an intensive six-day TC associated with nocturnal melatonin (n = 10) or placebo (n = 10) ingestion. Resting and post-RSA test blood samples were obtained before and after the TC. Compared to placebo, melatonin intake decreased resting oxidative stress markers (i.e, advanced oxidation protein products), leukocytosis (i.e. white blood cells (WBC), neutrophils (NE)) and biomarkers of cellular damage (i.e. creatine kinase (CK)). It also lowered post-exercise leukocytosis (i.e. WBC, NE, lymphocytes (LY), monocytes (MO)) and biomarkers of cellular damage (i.e. CK, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT)) and raised the activity of the main antioxidant enzymes (i.e. glutathione peroxidase (GPx), glutathione reductase (GR)). In addition, compared to placebo, melatonin reduced the deterioration of the best and total time during the RSA test after the TC. In conclusion, nocturnal melatonin supplementation during an intensive TC alleviated oxidative stress, leukocytosis and cellular damage and improved recovery of RSA performance in soccer players.

Relationship Between Bioimpedance Vector Displacement and Renal Function After a Marathon in Non-elite Runners

Purpose: This study investigates the relationship between whole-body bioimpedance vector displacement, using bioelectrical impedance vector analysis (BIVA), and renal function through serum biomarkers [creatinine, urea, sodium, C-reactive protein (CRP), and creatine kinase] and urine biomarkers after a marathon.

Methods: Bioimpedance measurements were taken among 19 non-elite runners at 24 h pre-race, immediately post-race, and at 48 h post-race. The bioimpedance measurements were analyzed by BIVA using the Hotelling’s T2 test. The runners were divided according to a cutoff of serum creatinine level immediately post-race in G1 (<1.2 mg/dl of serum creatinine level) and G2 (≥1.2 mg/dl of serum creatinine level). The increase of the serum creatinine levels in 83% of G2 runners was related to acute kidney injury (AKI) stage 1.

Results: Neither G1 nor G2 showed a creatinine clearance rate (CCr) lower than 60 ml/min. G2 showed a significant increase in CRP values at 48 h post-race vs baseline compared to G1 (P < 0.05), with over 5 mg/L (6.8–15.2) in 92% of the runners, and in CK values with over 215 U/L (282–1,882) at 48 h post-race in 100% of the runners. By BIVA, the 95% confidence ellipses of G2 showed shorter bioimpedance vectors than G1, with a noticeable minor Xc/H (P < 0.01), indicating an expansion on extracellular water and inflammation. The runners with 48 h post-race Xc/H values ≤30.5 Ω, with a decrease from −3 to −12% with respect to the Xc/H value at 24 h pre-race, indicated AKI stage 1 with 85.7% sensitivity and 91.7% specificity, with a direct correlation between AKI stage 1 with greater CRP values at 48 h post-race and bioimpedance vector displacement, but not with CK values at 48 h post-race.

Conclusion: Through this data collection, it was evidenced that a transient reduction in renal function is more related to inflammatory factors than muscle damage. The BIVA method along with serum biomarkers could be used to follow up the kidney function in runners.

Using dried orange pulp in the diet of dairy goats: effects on milk yield and composition and blood parameters of dams and growth performance and carcass quality of kids

Although dried orange pulp (DOP) may conveniently replace cereals in ruminant diets, few studies have considered similar diet substitution for goats. We hypothesised that DOP could replace cereal-based concentrate in goat diets without detrimental effects on growth performance and carcass quality of suckling kids and milk performance and blood biochemical parameters of dams in early lactation. We also hypothesised that DOP substitution may increase the levels of antioxidants, such as phenolic compounds and vitamin E, in milk and improve its total antioxidant capacity (TAC). Therefore, 44 primiparous Payoya dairy goats were allocated to three experimental groups, each fed a different diet: control (CD, n = 14) based on a commercial concentrate with alfalfa hay as forage; and DOP40 (n = 16) in which 40% and DOP80 (n = 14) in which 80% of the cereal in the concentrate were replaced by DOP. The experiment lasted from the final month of pregnancy to 55 days postpartum. The DOP diets did not affect suckling kids' carcass quality, but at 28 days, led to improvement in live weight (LW) and average daily gain (ADG) from birth, although no differences were found between DOP40 and DOP80 (for CD, DOP40 and DOP80, LW at 28 days was 8.00, 8.58 and 8.34 kg and ADG was 184, 199 and 195 g/day, respectively). Diet had no significant effect on milk yield (average daily milk yield and total yield at 55 days were 1.66 l/day and 90.6 l, respectively) and commercial and fatty acid composition. Nevertheless, α-tocopherol, total phenolic compound (TPC) and TAC concentration in milk increased with substitution of cereals by DOP (for CD, DOP40 and DOP80, concentration of α-tocopherol was 21.7, 32.8 and 42.3 μg/100 g, TPCs was 63.5, 84.1 and 102 mg gallic acid equivalents/l, and TAC was 6.63, 11.1 and 12.8 μmol Trolox equivalents/ml, respectively). Every plasma biochemistry parameter considered was within reference values for healthy goats; therefore, no pathological effect was detected for these variables due to dietary treatment. However, DOP diets caused a reduction in plasmatic creatine kinase and aspartate aminotransferase, implying reduced oxidative damage to muscles. In conclusion, DOP may be an interesting alternative to cereals in early lactation goat diets for increasing farmers' income and the healthy antioxidant capacity of milk.

Effectiveness of deferiprone-loaded nanocarrier in experimentally induced rhabdomyolysis: A dose-comparison study

Herein, the efficacy of free deferiprone (DFP) and DFP-loaded starch/polyethylene glycol/polyacrylic acid (St/PEG/PAAc) nanogel [Nano-DFP] in modulating the biochemical changes induced by glycerol model of rhabdomyolysis (RBD) in male rats was investigated. In this respect, gamma radiation-induced crosslinking was used to produce St/PEG/PAAc nanogel particles, and then, it was used as a nanocarrier for DFP as an attempt to overcome the poor bioavailability and short half-life of DFP. St/PEG/PAAc nanogel was characterized by Fourier transform infrared, dynamic light scattering and Transmission electron microscopy. Free DFP was administered to rats in two doses; 25 and 50 mg following RBD induction, while the loaded nanogel was administered at a dose of 25 mg. The liver and kidney functions were then fully assessed in association with the histological tissue examination of both organs and the femur muscle. Both doses of DFP significantly antagonized the RBD-induced changes in most of the assessed organs functions. The higher dose of DFP, however, showed a statistically more pronounced modulation of RBD effects on each of kidney, liver and skeletal muscles. Nano-DFP; at 25 mg dose, resulted in a statistically significant correction of most of the RBD-related biomarkers with a comparable magnitude to the higher DFP dose rather than the corresponding lower one.

Implications of maraviroc and/or rapamycin in a mouse model of fragility

Background: As age increases, the risk of developing fragility also increases. Improving the knowledge of frailty could contribute to maintaining the functional ability of elderly people. Interleukin (IL)-10 homozygous knockout mice (IL-10^tm/tm [IL10KO]) constitute an excellent tool for the study of frailty. Because patients with frailty demonstrate an overexpression of CCR5, rapamycin (RAPA) and/or maraviroc (MVC), two molecules able to decrease CCR5 expression, were evaluated.

Results: Muscle myostatin was reduced in all the therapeutic groups but the MVC group (p <0.001 for RAPA and MVC-RAPA) and in serum samples (p <0.01 for all the groups). Serum CK levels were also significantly lower in MVC and RAPA groups (p <0.01 in both cases). Lower AST levels were observed in all the therapeutic groups (p <0.05 for all of them). The apoptotic effector caspase-3 was significantly lower in MVC and RAPA groups (p<0.05 in both cases). Combined treatment with MVC-RAPA showed a synergistic increase in p-AKT, p-mTOR and SIRT1 levels.

Conclusions: MVC and RAPA show a protective role in some factors involved in frailty. More studies are needed to prove their clinical applications.

Material and methods: Eighty male homozygous IL10KOs were randomly assigned to one of 4 groups (n= 20): i) IL10KO group (IL10KO); ii) IL10KO receiving MVC in drinking water (MVC group), iii) IL10KO receiving RAPA in drinking water (RAPA group), and finally, iv) MVC-RAPA group that received MVC and RAPA in drinking water. Blood and muscle samples were analysed. Survival analysis, frailty index calculation, and functional assessment were also performed.

Exertional rhabdomyolysis and acute kidney injury in endurance sports: A systematic review

The increase of wide-spread participation in endurance events in sports such as open water swimming, cycling, running and triathlons, has given rise to a concern about potential implications for renal function and kidney health. This study aimed to delve into the findings on exertional rhabdomyolysis (ER) and acute kidney injury (AKI) in endurance sports, emphasizing the diagnostic criteria used, physical and environmental contextual conditions in which ER and AKI are reported. Following PRISMA guidelines for systematic reviews and meta-analysis, topic related studies were searched digital sources (from 2009 to 2020). Studies with biomarkers of ER and AKI reported in endurance or ultra-endurance events were included. A total of 43 publications (sample = 813) were extracted, and 345 (43.5%) individuals were diagnosed with ER (creatinine kinase > 5000 UI/L) and 130 (16.39%) with ER + AKI (creatinine ≥ 1.88 mg/dL). Out of the total cases of ER + AKI, 96.92% were in ultra-endurance runners. There were inconsistences between studies in diagnosis criteria for ER and AKI, which represented a difficulty in the interpretation of the data. Increased levels of muscle and kidney injury immediately after endurance events were reported, but after 5.86 days these levels usually returned to baseline. There is a lack of knowledge around the potential of repeated ER and AKI predisposing to long-term chronic kidney disease. More accurate markers for subclinical and functional AKI diagnosis are needed in the analysis of kidney health after endurance events. ER and AKI are serious clinical problems with significant morbidity. Further research may be in order to help define future prevention strategies.

Effect of Stem Cells, Ascorbic Acid and SERCA1a Gene Transfected Stem Cells in Experimentally Induced Type I Diabetic Myopathy

Background and Objectives

Sarco/endoplasmic reticulum Ca^2＋-ATPase (SERCA) inhibition was proved in streptozotocin (STZ)-diabetic rats. The present study aimed at investigating and comparing the therapeutic effect of bone marrow mesenchymal stem cells (BMMSCs), BMMSCs combined with ascorbic acid (AA) and SERCA1a gene transfected BMMSCs in induced type I diabetic myopathy of male albino rat.

Methods and Results

54 rats were divided into donor group of 6 rats for isolation, propagation and characterization of BMMSCs and SERCA1a transfected BMMSCs, groups I∼V 48 rats. Group I of 8 control rats, group II (Diabetic) of 10 rats given STZ 50 mg/kg intraperitoneal, group III (BMMSCs) of 10 rats given STZ and BMMSCs intravenous (IV), group IV (BMMSCs and AA) of 10 rats given STZ, BMMSCs IV and AA 500 mg/kg and group V (SERCA 1a transfected BMMSCs) of 10 rats given STZ and SERCA1a transfected BMMSCs IV. The rats were sacrificed after 8 weeks. Gastrocnemius specimens were subjected to biochemical, histological, morphometric and statistical studies. Diabetic rats revealed inflammatory and degenerative muscle changes, a significant increase in blood glucose level, mean DNA fragmentation and mean MDA values and a significant decrease in mean GSH and catalase values, area of pale nuclei, area% of CD105 and CD34 ＋ve cells, SERCA1a protein and gene values. The morphological changes regressed by therapy. In group III significant decrease in DNA fragmentation and MDA, significant increase in GSH and catalase, significant increase in the mean area of pale nuclei, area % of CD105 and CD34 ＋ve cells versus diabetic group. In group IV, same findings as group III versus diabetic and BMMSCs groups. In group V, same findings as group IV versus diabetic and treated groups. Western blot and PCR proved a mean value of SERCA1a protein and gene comparable to the control group. Mean calcium concentration values revealed a significant increase in the diabetic group, in BMMSCs and AA group versus control and SERCA1a group.

Conclusions

SERCA1a transfected BMMSCs proved a definite therapeutic effect, more remarkable than BMMSCs combined with AA. This effect was evidenced histologically and confirmed by significant changes in the biochemical tests indicating oxidative stress, muscle calcium concentration, morphometric parameters and PCR values of SERCA1a.

The effects of rapid weight loss on skeletal muscle in judo athletes

OBJECTIVE

To observe the effect of rapid weight loss (RWL) methods over 3 days on muscle damage in judokas.

METHODS

Eighteen judokas participated in this crossover study, meaning that judo athletes were subjected to exercise-only phase (4 days) and RWL phase (3 days). Subjects were tested for myoglobin, creatine kinase, aldolase, hemoglobin, and hematocrit values on seven consecutive days. These biomarkers served as indicators of acute muscle damage.

RESULTS

During the exercise-only phase, no significant changes were observed. Myoglobin (Mb) (p < 0.001), creatine kinase (CK) (p < 0.001) and aldolase (ALD) (p < 0.001) significantly increased only during the RWL phase, as well as hemoglobin (Hb) (p < 0.001) and hematocrit (Hct) (p < 0.005) values. It was detected that peak values for muscle damage biomarkers were reached on the sixth day, while Hct and Hb values were the highest on the seventh day of the study.

CONCLUSION

Our study showed significant muscle damage induced by RWL. The prevalence of RWL use by judokas is high but firm scientific evidence is lacking in the evaluation of the current practice of it. Therefore, further knowledge must be gained to evaluate the effectiveness of RWL on performance and its impact on judokas' wellbeing.

Elevated serum myoglobin levels at hospital admission and the risk of early death among patients with hemophagocytic lymphohistiocytosis: evidence from 155 pediatric patients

Patients with hemophagocytic lymphohistiocytosis (HLH) have high risk of early mortality. The purpose of this study was to test the hypothesis that the elevated level of serum myoglobin among patients with HLH is associated with disease severity and increased risk of mortality. We retrospectively investigated the serum myoglobin levels from 155 pediatric patients diagnosed with HLH in the Hunan Children's Hospital, China. The levels of myoglobin and creatine kinase at hospital admission among non-survivors and survivors were compared. The myoglobin level was dichotomized for the estimation of hazard ratio (HR) for mortality. Patients who died within 7 and 30 days of hospitalization had significantly higher myoglobin levels than did survivors (p < 0.05). The myoglobin level was negatively associated with the days of survival among non-survivors (Spearman correlation coefficient = - 0.29, p = 0.04). An elevated myoglobin level (> 90 ng/mL) was significantly associated with increased mortality (unadjusted HR = 2.66, 95%CI: 1.41, 5.00, p = 0.0024) and persisted after adjusting for age, Epstein-Barr virus infection, admission department, acute kidney injury, myocardial damage, and shock. In conclusion, an elevated serum myoglobin level was associated with increased risk of early death among pediatric patients with HLH, suggesting the potential of myoglobin to be used as a reference indicator for monitoring and managing of HLH.

Editorial for "Quantitative MRI Reveals Microstructural Changes in the Upper Leg Muscles After Running a Marathon"

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 5 J. Magn. Reson. Imaging 2020;52:418-419.

Association of low testosterone with changes in non-cardiovascular biomarkers in adult men

Testosterone has effects on many organs and systems. The purpose of this study was to test the hypothesis that low testosterone is associated with changes in various non-cardiovascular biomarkers in men older than 40 who were tested for possible hypogonadism. We extracted data from 9939 outpatient men who were over 40 years old (median age 56) and who also had concurrent laboratory measurements of total testosterone and one or more biomarkers of interest: estradiol, uric acid, prostate-specific antigen (PSA), sex-hormone binding globulin (SHBG), luteinizing hormone, creatinine, bone alkaline phosphatase (BAP), creatine kinase, hemoglobin A1c, and 25-hydroxy-vitamin D, and body mass index (BMI). In a smaller exploratory study of 19 otherwise healthy men presenting for evaluation of possible hypogonadism, pre-albumin (a.k.a.transthyretin, a marker of anabolism) and testosterone were measured. Men with lower levels of testosterone had significantly (p < 0.001) lower mean levels of PSA, SHBG, luteinizing hormone, and estradiol. Overall, men with low levels of testosterone also had significantly (p < 0.001) higher mean levels of LDH and BAP, but these associations varied between men who were younger or older than 56 years. There was a moderate but statistically significant positive correlation (r = 0.63, p < 0.05) between testosterone levels and pre-albumin. These results confirm our hypothesis that testosterone deficiency is associated with a broad range of systemic changes demonstrable in hormonal and non-hormonal serum assays in men over 40 years old being tested for possible hypogonadism.

The Impact of Aspirin Intake on Lactate Dehydrogenase, Arterial Stiffness, and Oxidative Stress During High-Intensity Exercise: A Pilot Study

Aspirin is a common nonsteroidal anti-inflammatory drug used to reduce fever, pain, and inflammation. However, aspirin's anti-inflammatory properties may also prevent increased levels of blood lactate dehydrogenase, vascular arterial stiffness and oxidative stress induced by high-intensity exercise. The purpose of this study was to investigate the effects of 4 weeks of aspirin supplementation on lactate dehydrogenase activity, lactate, arterial stiffness, and antioxidant capacity during high-intensity exercise in Taekwondo athletes. Participants were randomly divided into two groups: aspirin supplementation (n = 10) and placebo-control (n = 10). Blood levels of lactate dehydrogenase (LDH) enzyme activity and lactate were assessed to examine muscle damage and carotid-to-radial pulse wave velocity and the augmentation index were measured to examine arterial stiffness. Blood levels of superoxide dismutase, malondialdehyde, and glutathione peroxidase were assessed to determine antioxidant capacity and levels of oxidative stress. There were significant group × time interactions for enzyme activity of LDH (Δ-60 ± 24.36 U/L) and carotid-to-radial pulse wave velocity (Δ-1.33 ± 0.54 m/s), which significantly decreased (p < 0.05) following aspirin supplementation compared to placebo-control. Superoxide dismutase (Δ359 ± 110 U/gHb) and glutathione peroxidase (Δ28.2 ± 10.1 U/gHb) significantly decreased while malondialdehyde (0Δ3.0 ± 0.1 mmol/mL) significantly increased (p < 0.05) in the placebo-control group compared to the supplementation group. However, there were no changes in lactate concentration levels or augmentation index. These results reveal that low-dose aspirin supplementation would be a useful supplementation therapy to prevent high-intensity exercise training-induced increases in oxidative damage, inflammation, skeletal muscle fatigue, and arterial stiffness in elite Taekwondo athletes.

Severe Rhabdomyolysis in a Pediatric Patient after Coxsackie B Virus Infection without Acute Renal Failure: A Case Report

Rhabdomyolysis is a condition resulting from the breakdown of skeletal muscle fibers with leakage of muscle enzymes into the circulation. The degraded muscle components in the circulation can lead to lethal complications as acute renal failure (ARF). In younger children, viral infections tend to be the major cause while trauma and exercise are the important ones in adolescents. Several viruses such as influenza A & B, parainfluenza and coxsackie have been implicated in causing rhabdomyolysis. We report a case of a 14-year-old girl with severe rhabdomyolysis after recent Coxsackie B infection without acute renal failure.

Supplementation with a Mango Leaf Extract (Zynamite®) in Combination with Quercetin Attenuates Muscle Damage and Pain and Accelerates Recovery after Strenuous Damaging Exercise

Prolonged or unusual exercise may cause exercise-induced muscle damage (EIMD). To test whether Zynamite®, a mango leaf extract rich in the natural polyphenol mangiferin, administered in combination with quercetin facilitates recovery after EIMD, 24 women and 33 men were randomly assigned to two treatment groups matched by sex and 5 km running performance, and ran a 10 km race followed by 100 drop jumps to elicit EIMD. One hour before the competition, and every 8 hours thereafter for 24 hours, they ingested placebo (728 mg of maltodextrin) or 140 mg of Zynamite® combined with 140 mg of quercetin (double-blind). Although competition times were similar, polyphenol supplementation attenuated the muscle pain felt after the competition (6.8 ± 1.5 and 5.7 ± 2.2 a.u., p = 0.035) and the loss of jumping performance (9.4 ± 11.5 and 3.9 ± 5.2%, p = 0.036; p = 0.034) and mechanical impulse (p = 0.038) 24 hours later. The polyphenols attenuated the increase of serum myoglobin and alanine aminotransferase in men, but not in women (interaction p < 0.05). In conclusion, a single dose of 140 mg Zynamite® combined with 140 mg of quercetin, administered one hour before competition, followed by three additional doses every eight hours, attenuates muscle pain and damage, and accelerates the recovery of muscle performance.

The Effect of Orally Dosed Levagen+™ (palmitoylethanolamide) on Exercise Recovery in Healthy Males-A Double-Blind, Randomized, Placebo-Controlled Study

The aim of this study was to evaluate the effect of palmitoylethanolamide (PEA), a cannabimimetic compound and lipid messenger, on recovery from muscle damaging exercise. Twenty-eight healthy young male participants attended the laboratory four times on subsequent days. In the first visit, baseline characteristics were recorded before participants were randomized to consume either liquid PEA (167.5 mg Levagen+ with 832.5 mg maltodextrin) or a matched placebo (1 g maltodextrin) drink. Leg press exercise consisted of four sets at 80% of one repetition maximum followed by a performance set. Muscle soreness, thigh circumference, blood lactate concentration, biomarkers of muscle damage and inflammation, and transcription factor pathways were measured pre- and immediately post-exercise and again at 1, 2, 3, 24, 48, and 72 h post-exercise. The leg press exercise increased (p < 0.05) blood lactate concentration and induced muscle damage as evidenced by increased muscle soreness, thigh circumference, biomarkers of muscle damage, and concentrations of tumor necrosis factor-α. PEA reduced (p < 0.05) myoglobin and blood lactate concentrations and increased protein kinase B phosphorylation following exercise. Taken together, these results indicate PEA supplementation may aid in muscle recovery from repeat bouts of exercise performed within a short duration by reducing myoglobin and lactate concentration.

Deceleration, Acceleration, and Impacts Are Strong Contributors to Muscle Damage in Professional Australian Football

Gastin, PB, Hunkin, SL, Fahrner, B, and Robertson, S. Deceleration, acceleration, and impacts are strong contributors to muscle damage in professional Australian football. J Strength Cond Res 33(12): 3374-3383, 2019-The purpose of this study was to investigate the relationships between serum creatine kinase [CK], an indirect marker of muscle damage, and specific indices of match load in elite Australian football. Twenty-six professional players were assessed during a competitive Australian Football League (AFL) season. [CK] was collected 24-36 hours before match and 34-40 hours after match during 8 in-season rounds. An athlete-tracking technology was used to quantify match load. Generalized estimating equations and random forest models were constructed to determine the extent to which match-load indices and pre-match [CK] explained post-match [CK]. There was a 129 ± 152% increase in [CK] in response to AFL competition. Generalized estimating equations found that number of impacts >3g (p = 0.004) and game time (p = 0.016) were most strongly associated with post-match [CK]. Random forest, with considerably lower errors (130 vs. 316 U·L), found deceleration, acceleration, impacts >3g, and sprint distance to be the strongest predictors. Pre-match [CK] accounted for 11% of post-match [CK], and considerable interindividual and intraindividual variability existed in the data. Creatine kinase, an indicator of muscle damage, was considerably elevated as a result of AFL competition. Parametric and machine-learning analysis techniques found several indices of physical load associated with muscle damage during competition, with impacts >3g and high-intensity running variables as the strongest predictors. [CK] may be used as a global measure of muscle damage in field team sports such as AF, yet with some caution given cost, invasiveness, and inherent variability. Quantifying physical load and the responses to that load can guide athlete management decision-making and is best undertaken within a suite of practical, sport-specific measures, where data are interpreted individually and with an understanding of the limitations.

Effects of a Futsal Game on Metabolic, Hormonal, and Muscle Damage Indicators of Male Futsal Players

Bekris, E, Gioldasis, A, Gissis, I, Katis, A, Mitrousis, I, and Mylonis, E. Effects of a futsal game on metabolic, hormonal and muscle damage indicators of male futsal players. J Strength Cond Res XX(X): 000-000, 2020-The aim of this study was to examine the effects of a futsal game on several metabolic, hormonal, and muscle damage indicators. Twenty-one male top-level futsal players participated in the study. Players were divided into 2 groups according to playing time: the long playing time (LPT) group and the short playing time (SPT) group. Game intensity parameters such as percentage of the HRmax and blood lactate concentration, as well as metabolic, hormonal, and muscle damage indicators were examined before and after a futsal game. The results showed that during the game, the intensity was up to 93% of HRmax and lactate concentrations ranged from 5.8 to 21.8 mmol·L. The LPT group showed an increased lactate dehydrogenase level compared with the SPT group (p < 0.05). Similarly, creatine kinase was significantly increased in the LPT group (p < 0.05) after the game. By contrast, nonsignificant differences were observed between groups for alanine transaminase (ALT-SGPT), aspartate transaminase (AST-SGOT), and gamma-glutamyl transferase enzymes (p > 0.05). The testosterone/cortisol ratio (T/C) reduced for both groups after the game (p < 0.05). The results of this study indicated that a futsal game have a significantly effect on several hormonal, metabolic, and muscle damage indicators for players who participate for a longer playing time in the game. Therefore, the evaluation of these volumes could assist coaches to organize specific, effective, and individualized training programs.

Long-Term Effect of Combination of Creatine Monohydrate Plus β-Hydroxy β-Methylbutyrate (HMB) on Exercise-Induced Muscle Damage and Anabolic/Catabolic Hormones in Elite Male Endurance Athletes

Creatine monohydrate (CrM) and β-hydroxy β-methylbutyrate (HMB) are widely studied ergogenic aids. However, both supplements are usually studied in an isolated manner. The few studies that have investigated the effect of combining both supplements on exercise-induced muscle damage (EIMD) and hormone status have reported controversial results. Therefore, the main purpose of this study was to determine the effect and degree of potentiation of 10 weeks of CrM plus HMB supplementation on EIMD and anabolic/catabolic hormones. This study was a double-blind, placebo-controlled trial where participants (n = 28) were randomized into four different groups: placebo group (PLG; n = 7), CrM group (CrMG; 0.04 g/kg/day of CrM; n = 7), HMB group (HMBG; 3 g/day of HMB; n = 7), and CrM-HMB group (CrM-HMBG; 0.04 g/kg/day of CrM plus 3 g/day of HMB; n = 7). Before (baseline, T1) and after 10 weeks of supplementation (T2), blood samples were collected from all rowers. There were no significant differences in the EIMD markers (aspartate aminotransferase, lactate dehydrogenase, and creatine kinase) among groups. However, we observed significant differences in CrM-HMBG with respect to PLG, CrMG, and HMBG on testosterone (p = 0.006; η2p = 0.454) and the testosterone/cortisol ratio (T/C; p = 0.032; η2p = 0.349). Moreover, we found a synergistic effect of combined supplementation on testosterone (CrM-HMBG = -63.85% vs. CrMG + HMBG = -37.89%) and T/C (CrM-HMBG = 680% vs. CrMG + HMBG = 57.68%) and an antagonistic effect on cortisol (CrM-HMBG = 131.55% vs. CrMG + HMBG = 389.99%). In summary, the combination of CrM plus HMB showed an increase in testosterone and T/C compared with the other groups after 10 weeks of supplementation. Moreover, this combination presented a synergistic effect on testosterone and T/C and an antagonistic effect on cortisol compared with the sum of individual or isolated supplementation.

Serum Autofluorescence and Biochemical Markers in Athlete's Response to Strength Effort in Normobaric Hypoxia: A Preliminary Study

The human organism has the ability to adapt to hypoxia conditions. Training in hypoxia is used in sport to improve the efficiency of athletes; however, type of training affects the direction and scope of this process. Therefore, in this study, the usefulness of serum fluorescence spectroscopy to study the assessment of athlete's response to strength effort in hypoxia is considered in comparison with biochemical assay. Six resistance-trained male subjects took part in a research experiment. They performed barbell squats in simulated normobaric hypoxic conditions with deficiency of oxygen 11.3%, 13% 14.3% compared to 21% in normoxic conditions. Fluorescence intensity of tyrosine revealed high sensitivity on strength effort whereas tryptophan was more dependent on high altitude. Changes in emission in the visible region are associated with altering cell metabolism dependent on high altitude as well as strength training and endurance training. Significant changes in serum fluorescence intensity with relatively weak modifications in biochemical assay at 3000 m above sea level (ASL) were observed. Training at 5000 m ASL caused changes in fluorescence parameters towards the normobaric specific values, and pronounced decreases of lactate level and kinase creatine activity were observed. Such modifications of fluorescence and biochemical assay indicate increased adaptation of the organism to effort in oxygen-deficient conditions at 5000 m ASL, unlike 3000 m ASL. Fluorescence spectroscopy study of serum accompanied by biochemical assay can contribute to the understanding of metabolic regulation and the physiological response to hypoxia. The results of serum autofluorescence during various concepts of altitude training may be a useful method to analyze individual response to acute and chronic hypoxia. An endogenous tryptophan could be exploited as intrinsic biomarker in autofluorescence studies. However, these issues require further research.

Differences on salivary proteome at rest and in response to an acute exercise in men and women: A pilot study

The aim of the present study was to evaluate the differences in salivary proteome at rest and in response to an acute exercise in men and women. For this, unstimulated whole saliva samples in rest and after a bout resistance exercise leading to failure (ELF) of both men and women (n = 5 for each sex) were subjected to isobaric Tandem Mass Tags (TMT) labelling followed by LC-MS/MS. A total of 274 proteins were identified and met the inclusion criteria. 16 proteins were modulated for the interaction sex*exercise, 6 were modulated because of the exercise, and 65 were differentially expressed between men and women at rest. In conclusion, these results indicate sex-related differences in the salivary proteome at rest and after an acute exercise, pointing out possible candidate biomarkers for sports performance and allowing further knowledge of the physiological processes occurring during ELF. SIGNIFICANCE: The present study describes for the first time the changes that occur in salivary proteome detected by TMT-based proteomics in response to an acute exercise and the differences in these changes depending on sex. Of the 274 protein identified, the 87 differentially expressed proteins and their related pathways were discussed, focusing on the sex- and exercise-related differences in the salivary proteome.

Changes in urinary titin N-terminal fragments as a biomarker of exercise-induced muscle damage in the repeated bout effect

OBJECTIVES

Muscle damage symptoms induced by unaccustomed eccentric contraction exercise can be reduced by repeating the experience several times. This phenomenon is termed the repeated bout effect. Although traditional biochemical markers require invasive blood sampling, biochemical measurements have recently been developed that can be non-invasively performed using urinary titin N-terminal fragment (UTF). However, it is unclear whether UTF can reflect the repeated bout effect. Therefore, the aim of the present study was to clarify whether UTF decreased with the repeated bout effect.

DESIGN

This study compared changes in muscle damage markers between bouts of exercise performed for the first and second time.

METHODS

Eight young men performed 30 eccentric exercises of the elbow flexor on the first day of the first week (Bout 1). A second bout of eccentric exercises, same as the first, was performed 2 weeks later, (Bout 2). The dependent variables were muscle soreness (SOR), maximal voluntary isometric contraction (MVIC), range of motion (ROM), creatine kinase (CK), and UTF. All dependent variables were analyzed using two-way analysis of variance.

RESULTS

No significant difference was observed in workload or peak torque between the first and second exercise bouts. SOR as well as CK and UTF were significantly lower and ROM and MVIC were significantly higher in Bout 2 in comparison to Bout 1.

CONCLUSIONS

These results suggest that UTF sensitively reflects the repeated bout effect and exercise-induced muscle damage can be non-invasively measured.

Corticosterone-mediated physiological stress modulates hepatic lipid metabolism, metabolite profiles, and systemic responses in chickens

The impact of physiological stress on lipid metabolism, the metabolome, and systemic responses was examined in chickens. To incite a stress response, birds were continuously administered corticosterone (CORT) in their drinking water at three doses (0 mg/L, 10 mg/L, and 30 mg/L), and they were sampled 1, 5, and 12 days after commencement of CORT administration. Corticosterone administration to birds differentially regulated lipogenesis genes (i.e. FAS, ACC, ME, and SREBF1), and histopathological examination indicated lipid deposition in hepatocytes. In addition, CORT affected water-soluble metabolite profiles in the liver, as well as in kidney tissue and breast muscle; thirteen unique metabolites were distinguished in CORT-treated birds and this was consistent with the dysregulation of lipid metabolism due to physiological stress. Acute phase responses (APRs) were also altered by CORT, and in particular, expression of SAA1 was decreased and expression of CP was increased. Furthermore, CORT administration caused lymphoid depletion in the bursa of Fabricius and elevated IL6 and TGFβ2 mRNA expression after 5 and 12 days of CORT administration. Collectively, incitement of physiological stress via administration of CORT in chickens modulated host metabolism and systemic responses, which indicated that energy potentials are diverted from muscle anabolism during periods of stress.

Infrared Low-Level Laser Therapy (Photobiomodulation Therapy) before Intense Progressive Running Test of High-Level Soccer Players: Effects on Functional, Muscle Damage, Inflammatory, and Oxidative Stress Markers-A Randomized Controlled Trial

The effects of preexercise photobiomodulation therapy (PBMT) to enhance performance, accelerate recovery, and attenuate exercise-induced oxidative stress were still not fully investigated, especially in high-level athletes. The aim of this study was to evaluate the effects of PBMT (using infrared low-level laser therapy) applied before a progressive running test on functional aspects, muscle damage, and inflammatory and oxidative stress markers in high-level soccer players. A randomized, triple-blind, placebo-controlled crossover trial was performed. Twenty-two high-level male soccer players from the same team were recruited and treated with active PBMT and placebo. The order of interventions was randomized. Immediately after the application of active PBMT or placebo, the volunteers performed a standardized high-intensity progressive running test (ergospirometry test) until exhaustion. We analyzed rates of oxygen uptake (VO_{2 max}), time until exhaustion, and aerobic and anaerobic threshold during the intense progressive running test. Creatine kinase (CK) and lactate dehydrogenase (LDH) activities, levels of interleukin-1β (IL-1-β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α), levels of thiobarbituric acid (TBARS) and carbonylated proteins, and catalase (CAT) and superoxide dismutase (SOD) activities were measured before and five minutes after the end of the test. PBMT increased the VO_{2 max} (both relative and absolute values—p < 0.0467 and p < 0.0013, respectively), time until exhaustion (p < 0.0043), time (p < 0.0007) and volume (p < 0.0355) in which anaerobic threshold happened, and volume in which aerobic threshold happened (p < 0.0068). Moreover, PBMT decreased CK (p < 0.0001) and LDH (p < 0.0001) activities. Regarding the cytokines, PBMT decreased only IL-6 (p < 0.0001). Finally, PBMT decreased TBARS (p < 0.0001) and carbonylated protein levels (p < 0.01) and increased SOD (p < 0.0001)and CAT (p < 0.0001) activities. The findings of this study demonstrate that preexercise PBMT acts on different functional aspects and biochemical markers. Moreover, preexercise PBMT seems to play an important antioxidant effect, decreasing exercise-induced oxidative stress and consequently enhancing athletic performance and improving postexercise recovery. This trial is registered with Clinicaltrials.gov NCT03803956.

Monitoring the Athlete Match Response: Can External Load Variables Predict Post-match Acute and Residual Fatigue in Soccer? A Systematic Review with Meta-analysis

BACKGROUND

Monitoring athletes' external load during a soccer match may be useful to predict post-match acute and residual fatigue. This estimation would allow individual adjustments to training programs to minimize injury risk, improve well-being, and restore players' physical performance and inform the recovery process.

METHODS

Using a systematic review and meta-analysis of the literature, the aim is to determine which monitoring variables would be the strongest predictors of acute (immediately) and residual (up to 72 h) fatigue states in soccer. PubMed, SPORTDiscus, and Web of Science databases were searched (until September 2018). Studies concurrently examining soccer match-related external load metrics and subjective and/or objective measures were selected to determine pooled correlations ([Formula: see text]) with confidence intervals (CI). The quality and strength of the findings of each study were evaluated to identify overall levels of evidence.

RESULTS

Eleven studies were included (n = 165 athletes). Acute ([Formula: see text] = 0.67; 95% CI = [0.40, 0.94]) and residual (24 h post-match, [Formula: see text] = 0.54; 95% CI = [0.35, 0.65]) changes in muscle damage markers and countermovement jump peak power output (CMJ_PPO) were, with moderate to strong evidence, largely correlated with running distance above 5.5 m s^-1. No other external load metric was largely correlated with both biochemical and neuromuscular markers. For every 100-m run above 5.5 m·s^-1, CK activity measured 24 h post-match increased by 30% and CMJ_PPO decreased by 0.5%. Conversely, the total distance covered did not present any evidence of a clear relationship with any fatigue-related marker at any time-point.

CONCLUSIONS

Running distance above 5.5 m·s^-1 represents the most sensitive monitoring variable characterizing biochemical and neuromuscular responses, at least when assessed during the initial 24 h (not at 48 h/72 h) post-match recovery period. In addition, total distance covered is not sensitive enough to inform decision-making during the fatigue monitoring process.