Creatine kinase isoenzyme activity during and after an ultra-distance (200 km) run

The Impact of Normobaric Hypoxia and Intermittent Hypoxic Training on Cardiac Biomarkers in Endurance Athletes: A Pilot Study

This study explores the effects of normobaric hypoxia and intermittent hypoxic training (IHT) on the physiological condition of the cardiac muscle in swimmers. Hypoxia has been reported to elicit both beneficial and adverse changes in the cardiovascular system, but its impact on the myocardium during acute exercise and altitude/hypoxic training remains less understood. We aimed to determine how a single bout of intense interval exercise and a four-week period of high-intensity endurance training under normobaric hypoxia affect cardiac marker activity in swimmers. Sixteen young male swimmers were divided into two groups: one undergoing training in hypoxia and the other in normoxia. Cardiac markers, including troponin I and T (cTnI and cTnT), heart-type fatty acid-binding protein (H-FABP), creatine kinase-MB isoenzyme (CK-MB), and myoglobin (Mb), were analyzed to assess the myocardium's response. We found no significant differences in the physiological response of the cardiac muscle to intense physical exertion between hypoxia and normoxia. Four weeks of IHT did not alter the resting levels of cTnT, cTnI, and H-FABP, but it resulted in a noteworthy decrease in the resting concentration of CK-MB, suggesting enhanced cardiac muscle adaptation to exercise. In contrast, a reduction in resting Mb levels was observed in the control group training in normoxia. These findings suggest that IHT at moderate altitudes does not adversely affect cardiac muscle condition and may support cardiac muscle adaptation, affirming the safety and efficacy of IHT as a training method for athletes.

The relationship between cardiac damage biomarkers and heart rate variability following 60 min of running

PURPOSE

Endurance exercise may cause transient alterations in cardiac tissue. The number of studies evaluating the relationship between changes in heart rate variability (HRV) and cardiac biomarkers following an endurance event is limited. We hypothesized that there would be a time-dependent correlation between biomarkers of cardiac damage and the reduction in parasympathetic indices of HRV within 24 h after 60 min of running in middle-aged recreational runners.

METHODS

The trained, middle-aged runners who participated in this study ran 60 min at a half-marathon pace on a treadmill. Blood samples (before and 0, 4, and 24 h after the running test) and HRV data (before and 0, 1, 4, and 24 h after the running test) were obtained.

RESULTS

After running, cardiac biomarkers (total creatine kinase, cardiac isoform of creatine kinase, creatine kinase-index [CK-Index], cardiac troponin [cTnI]) increased significantly, and HRV measures related to parasympathetic nervous system activity decreased significantly; these measures returned to baseline levels within 24 h. Finally, there were significant correlations (all p < 0.05) between the change (4 h post-running vs. pre-running) in the CK-Index and the changes (post- vs pre-running) in time-domain and nonlinear measures of HRV (r - 0.61 to - 0.67). In addition, significant correlations (all p < 0.05) were found between the area under the cTnI curve and change (1-h post- and pre-running) in time-domain and nonlinear measures of HRV (r - 0.48 to - 0.51).

CONCLUSIONS

The correlation between HRV and cardiac biomarkers indicates that HRV analysis may be an alternative approach to determine the magnitude of cardiac stress after endurance exercises.

Guinness World Record: Personal Experience and Physiological Responses of a Non-Professional Athlete Successfully Covering 620 Km in 7-Days by Foot Across the United Arab Emirates

Ultra-endurance record-breaking attempts place significant metabolic, cardiovascular, and mechanical stress on the athlete. This research explores the personal experience and physiological responses of a non-professional athlete attempting the Guinness World Record of covering 620 km on foot across the United Arab Emirates in 7-days or less. The participant wore a smartwatch throughout the challenge to collect heart rate, activity, and environmental temperature data. Anthropometric, body composition, and inflammatory, haematological, and endocrine biomarkers measurements were completed pre- and post-event. A pre- and post-event interview was conducted to collect data on training and preparation, and self-reported experiences during the challenge. Despite episodes of diarrhoea, vomiting, and muscle cramps due to hypohydration during the first days of the challenge, the participant successfully completed 619.01 km in six days, 21 hours, and 47 minutes (average pace 10.11 min/km) achieving a new Guinness World Record. Body mass remained unchanged, fat mass decreased, and fat-free mass especially in the legs increased over the seven days, most likely due to water retention. Biomarkers of stress, cell damage, and inflammation increased. Haematological markers related to red blood cells decreased probably due to exercise-induced increases in plasma volume with the participant classified with mild anaemia post-event. This case study reinforces the importance of amateur athletes attempting similar ultra-endurance events adhering to a pre-planned hydration and nutrition strategy to maximise performance and minimise the risk of injury.

The Consequences of Training and Competition to the Musculoskeletal System in Ultramarathon Runners: A Narrative Review

Ultramarathons are becoming increasingly popular every year, leading to more and more publications focusing on athletes of these endurance events. This paper summarizes the current state of knowledge on the effects of ultramarathons on the motor system. Various studies have attempted to answer questions about negative and positive effects on the musculoskeletal system, common injuries, optimal strategies, and regeneration. Considering the increasing number of ultramarathon athletes, the discoveries may have practical applications for a multitude of experts in the field of sports medicine, as well as for the athletes themselves. Acute locomotor system changes in runners as assessed by locomotor biomarkers are reversible and may be asymptomatic or painful. Injuries suffered by runners largely allow them to finish the competition and are usually overlooked. Regeneration, including regular massage and the use of supporting techniques, allows for faster convalescence. This publication is meant to be a source of knowledge for people associated with this discipline.

Effects of exercise training and statin on hemodynamic, biochemical, inflammatory and immune profile of people living with HIV: a randomized, double-blind, placebo-controlled trial

BACKGROUND

The aim of this study is to evaluate the effect of exercise training (ET) and statins on the hemodynamic, biochemical, inflammatory and immune profile of people living with HIV (PLHIV).

METHODS

This was a randomized, double-blind, placebo-controlled clinical trial in which 83 PLHIV were assigned to either placebo (PL), statins (STA), placebo + ET (PLET), or statins + ET (STAET) groups. Volunteers assigned to STA and STAET groups were administered 10 mg of rosuvastatin, whereas the PL and PLET groups were administered a placebo. The PLET and STAET groups performed ET three times a week. Before and after the 12-week follow-up, volunteers underwent blood collection to assess the biochemical, inflammatory, and immune profile.

RESULTS

There were significant time x group interaction effects (P<0.05) for all variables except for diastolic blood pressure. The PLET and STAET groups had significantly (P<0.05) decreased systolic blood pressure, resting heart rate, fasting glucose, glycated hemoglobin, fasting insulin, homeostatic model assessment for insulin resistance, creatine kinase, lactate, and TNF-α levels, and increased adiponectin, CD4⁺, and CD8⁺ levels. There was also a significant group effect (P<0.05) for CK levels among the exercised (PLET and STAET) and STA groups. The latter had a significant increase in fasting glucose (P<0.05) and creatine kinase (P<0.05).

CONCLUSIONS

ET improved the hemodynamic, biochemical, inflammatory, and immune profile of PLHIV and this effect was not dependent on the use of statins.

Exercise Is Medicine? The Cardiorespiratory Implications of Ultra-marathon

Regular physical activity decreases the risk of cardiovascular disease, type II diabetes, obesity, certain cancers, and all-cause mortality. Nevertheless, there is mounting evidence that extreme exercise behaviors may be detrimental to human health. This review collates several decades of literature on the physiology and pathophysiology of ultra-marathon running, with emphasis on the cardiorespiratory implications. Herein, we discuss the prevalence and clinical significance of postrace decreases in lung function and diffusing capacity, respiratory muscle fatigue, pulmonary edema, biomarkers of cardiac injury, left/right ventricular dysfunction, and chronic myocardial remodeling. The aim of this article is to inform risk stratification for ultra-marathon and to edify best practice for personnel overseeing the events (i.e., race directors and medics).

Diastolic Function and Biomarkers of Long-Distance Walking Participants

BACKGROUND

The effects of long-distance walking on the cardiovascular system have been little studied.

OBJECTIVES

The general objective of this study was to verify these effects on the behavior of diastolic function and the cardiac biomarkers CK-MB (mass), troponin T, and NT-proBNP, in amateur athletes.

METHOD

This longitudinal study, conducted in 2015, evaluated participants during the following 5 stages: E0 (baseline) before starting the trajectory and the others, E1, E2, E3, and E4, at the end of each day, totaling 244.7 km. At all stages, the biomarkers NT-proBNP, CK-MB (mass), and troponin T were measured. Echocardiogram was performed to analyze the E, A and E' waves. P < 0.05 was adopted as significant.

RESULTS

The study evaluated 25 participants, with an average age of 46 ± 10.5 years and body mass index of 20.2 ± 2.3 kg/m2. Increased values were found for NT-proBNP from E0 to E1, E2, E3, and E4 (p < 0.001), CK-MB (mass) from E0 to E2 (p < 0.001), and E' wave from E0 to E1, E2, E3, and E4 (p < 0.001). Positive correlations were identified between the following: CK-MB (mass) and troponin T (E1: r = 0.524, p = 0.010; E4: r = 0.413, p = 0.044); CK-MB (mass) and NT-proBNP (E4: r = 0.539, p = 0.006); and E/A and E' (E0: r = 0.603, p < 0.001; E1: r = 0.639, p < 0.001; E4: r = 0.593, p = 0.002). A negative correlation was found between CK-MB (mass) and E/A (E1: r = -0.428, p = 0.041).

CONCLUSION

The effects of intense, prolonged, and interspersed physical activity were verified based on significant variations in the behavior of CK-MB (mass), NT-proBNP, and the E' wave. Notwithstanding the alterations found, there were no criteria suggestive of myocardial damage.

Ultra-Endurance Associated With Moderate Exercise in Rats Induces Cerebellar Oxidative Stress and Impairs Reactive GFAP Isoform Profile

Ultra-endurance (UE) race has been associated with brain metabolic changes, but it is still unknown which regions are vulnerable. This study investigated whether high-volume training in rodents, even under moderate intensity, can induce cerebellar oxidative and inflammatory status. Forty-five adult rats were divided into six groups according to a training period, followed or not by an exhaustion test (ET) that simulated UE: control (C), control + ET (C-ET), moderate-volume (MV) training and MV-ET, high-volume training (HV) and HV-ET. The training period was 30 (MV) and 90 (HV) min/day, 5 times/week for 3 months as a continuous running on a treadmill at a maximum velocity of 12 m/min. After 24 h, the ET was performed at 50% maximum velocities up to the animals refused to run, and then serum lactate levels were evaluated. Serum and cerebellar homogenates were obtained 24 h after ET. Serum creatine kinase (CK), lactate dehydrogenase (LDH), and corticosterone levels were assessed. Lipid peroxidation (LP), nitric oxide (NO), Interleukin 1β (IL-1β), and GFAP proteins, reduced and oxidized glutathione (GSH and GSSG) levels, superoxide dismutase (SOD) and catalase (CAT) activities were quantified in the cerebellum. Serum lactate concentrations were lower in MV-ET (∼20%) and HV-ET (∼40%) compared to the C-ET group. CK and corticosterone levels were increased more than ∼ twofold by HV training compared to control. ET increased CK levels in MV-ET vs. MV group (P = 0.026). HV induced higher LP levels (∼40%), but an additive effect of ET was only seen in the MV-ET group (P = 0.02). SOD activity was higher in all trained groups vs. C and C-ET (P < 0.05). CAT activity, however, was intensified only in the MV group (P < 0.02). The 50 kDa GFAP levels were enhanced in C-ET and MV-ET vs. respective controls, while 42 kDa (∼40%) and 39 kDa (∼26%) isoform levels were reduced. In the HV-ET group, the 50 KDa isoform amount was reduced ∼40-60% compared to the other groups and the 39 KDa isoform, increased sevenfold. LDH levels, GSH/GSSG ratio, and NO production were not modified. ET elevated IL-1β levels in the CT and MV groups. Data shows that cerebellar resilience to oxidative damage may be maintained under moderate-volume training, but it is reduced by UE running. High-volume training per se provoked systemic metabolic changes, cerebellar lipid peroxidation, and unbalanced enzymatic antioxidant resource. UE after high-volume training modified the GFAP isoform profile suggesting impaired astrocyte reactivity in the cerebellum.

Repetitive Bouts of Exhaustive Exercise Induces a Systemic Inflammatory Response and Multi-Organ Damage in Rats

Multiple organ dysfunction syndrome can follow severe infection or injury, but its relationship to exercise is not well understood. Previous studies have observed that prolonged strenuous exercise can lead to transiently increased level and/or activity of markers for systemic inflammatory response and multiple organ damage. However, few studies have analyzed the pathogenesis of the inflammatory response and subsequent multi-organ injury in exhaustive exercise conditions. In this study, we established a rat model of repetitive bouts of exhaustive running (RBER) and investigated its effects on multiple organ damage. Rats were subjected to RBER in either uphill or downhill running modes daily for a period of 7 days. Morphologically, RBER causes tissue structural destruction and infiltration of inflammatory cells in the skeletal muscles and many visceral organs. RBER also causes sustained quantitative changes in leukocytes, erythrocytes, and platelets, and changes in the concentration of blood inflammatory factors. These inflammatory alterations are accompanied by increases in serum enzyme levels/activities which serve as functional markers of organ damage. In general, RBER in the downhill mode seemed to cause more damage evaluated by the above-mentioned measures than that produced in the uphill mode. A period of rest could recover some degree of damage, especially for organs such as the heart and kidneys with strong compensatory capacities. Together, our data suggest that, as a result of multi-organ interactions, RBER could cause a sustained inflammatory response for at least 24 h, resulting in tissue lesion and ultimately multiple organ dysfunction.

The effect of vitamin D supplementation on serum total 25(OH) levels and biochemical markers of skeletal muscles in runners

Background

The beneficial adaptation of skeletal muscle function to strenuous exercise is partially attributable to the improvement of vitamin D status. The present study aimed to evaluate the effects of a 3-week vitamin D supplementation on serum 25(OH)D levels and skeletal muscle biomarkers (i.e. troponin, myoglobin, creatine kinase and lactic dehydrogenase) of endurance runners.

Methods

A double-blind placebo-controlled study design was used and vitamin D supplementation was compared to a non-treatment control group. Twenty-four runners, competitors of the ultra-marathons held during the National Running Championships, were randomly assigned into two groups supplemented with the dose of 2000 IU vitamin D or placebo for three weeks. All subjects participated in three exercise protocols: (a) incremental exercise test (to determine the maximum oxygen uptake and the intensity of eccentric exercise), (b) eccentric exercise before and (c) after two dietary protocols. Venous blood samples were drawn at rest, immediately after the exercise and after 1 h and 24 h of recovery in order to estimate serum 25(OH)D levels, skeletal muscle biomarkers, proinflammatory cytokines and tumor necrosis factor-alpha (TNF-α) levels. A two-way ANOVA was used to test main effects and their interactions and Pearson correlation coefficients were analyzed to determine the effects of inter-variable relationships.

Results

Significant differences between pre- and post-intervention in baseline 25(OH)D levels were observed (34.9 ± 4.7 versus 40.3 ± 4.9 ng/ml, p = 0.02) in supplemented group. A higher post intervention 25(OH)D level was observed after vitamin D diet compared to placebo (40.3 ± 4.9 versus 31.8 ± 4.2 ng/mL, respectively; p < 0.05). The vitamin D supplementation decreased post-exercise (TN max) and 1 h post-exercise troponin (p = 0.004, p = 0.03, respectively), 1 h post-exercise myoglobin concentration (p = 0.01) and TNF-α levels(p < 0.03). 24 h post exercise creatine kinase activity was significantly lower in supplemented group compared to placebo (p < 0.05). A negative correlation was observed between post exercise 25(OH)D levels and myoglobin levels (r = − 0.57; p = 0.05), and 25(OH)D levels and TNFα (r = − 0.58; p = 0.05) in vitamin D supplemented group.

Conclusions

Three weeks of vitamin D supplementation had a positive effect on serum 25(OH)D levels in endurance trained runners and it caused a marked decrease in post-exercise biomarkers levels. We concluded that vitamin D supplementation might play an important role in prevention of skeletal muscle injuries following exercise with eccentric muscle contraction in athletes.

International Society of Sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing

Background

In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~ 60% of energy intake, 5–8 g·kg^− 1·d^− 1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~ 1.6 g·kg^− 1·d^− 1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g.kg^− 1·d^− 1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150–400 Kcal·h^− 1 (carbohydrate, 30–50 g·h^− 1; protein, 5–10 g·h^− 1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450–750 mL·h^− 1 (~ 150–250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., > 575 mg·L^− 1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.

A Randomized Controlled Trial Investigating the Effects of Undulatory, Staggered, and Linear Load Manipulations in Aerobic Training on Oxygen Supply, Muscle Injury, and Metabolism in Male Recreational Runners

Background

Taper is considered as a strategy to avoid overtraining and increase peak performance in athletes. Because aerobic exercise increases the level and duration of independence during the lifespan, the participation of recreational athletes has increased in running events around the world. However, the effects of using load reduction in their training and aerobic performance are still not well known.

Objectives

Our goal was to compare load manipulations, using tapering-like periods in the end of recreational athletes training evaluating alterations in oxygen supply, muscle injury, and metabolism markers.

Methods

Healthy males (n = 88, 20–35 years old) were randomly distributed in groups using a combination of two mesocycles of 4 weeks, undulatory and staggered, with two daily microcycles, undulatory and linear. Undulatory-undulatory (Und-Und) and undulatory-linear (Und-Lin) groups had load reduction in the final week of training while the staggered-undulatory (Sta-Und) and staggered-linear (Sta-Lin) groups did not. Cardiorespiratory capacity (V̇O_2max), body mass index (BMI), and body fat % were evaluated. Blood samples were also collected to analyze hematocrit (Ht), mean corpuscular hemoglobin (MCHC), circulating levels of hemoglobin (Hb), creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea (U), cortisol (C), free testosterone (FT), and free T/C ratio.

Results

After 8 weeks of training, Und-Und had the highest trend to increase V̇O_2max. Both Und-Und and Sta-Lin reduced body fat %. Und-Und showed a significant increase in MCHC, T and Free T/C ratio, a positive trend to increase Ht% and Hb levels, and a trend to decrease CK, LDH, and C circulating levels. Sta-Lin presented a trend to decrease Ht% and Hb levels, a significant increase in CK, LDH, AST, ALT circulating levels, and a decrease in Free T/C ratio.

Conclusion

The use of daily undulatory training load provides better gains for aerobic fitness while the use of staggered load, mainly associated with linear load, promotes inadequate recovery in recreational runners.

Acute Responses of Novel Cardiac Biomarkers to a 24-h Ultra-Marathon

The aim of the present study was to examine the acute effect of an ultra-endurance performance on N-terminal pro-brain natriuretic peptide (NT-proBNP), cardiac specific troponin T (cTnT), creatinine kinase-myocardial band (CK-MB), high sensitive C-reactive protein (hsCRP), ischemia modified albumin (IMA), heart-type fatty acid binding protein (H-FABP) and cardiovascular function. Cardiac biomarkers were evaluated in 14 male ultra-marathoners (age 40 ± 12 years) during a 24 h ultra-marathon at five points (i.e., Pre-race; Marathon, 12-h run, 24-h run, and 48-h post-race). All subjects underwent baseline echocardiography assessment at least 10 days prior to the ultra-marathon and 48 h post-race. The average distance covered during the race was 149.4 ± 33.0 km. Running the ultra-marathon led to a progressive increase in hsCRP and H-FABP concentrations (p < 0.001). CK-MB and cTnT levels were higher after a 24-h run compared to pre-race (p < 0.05). Diastolic function was altered post-race characterized by a reduction in peak early to late diastolic filling (p < 0.01). Running an ultra-marathon significantly stimulates specific cardiac biomarkers; however, the dynamic of secretion of biomarkers linked to myocardium ischemia were differentially regulated during the ultra-marathon race. It is suggested that both exercise duration and intensity play a crucial role in cardiovascular adaptive mechanisms and cause risk of cardiac stress in ultra-marathoners.

Blood Biomarkers in Sports Medicine and Performance and the Future of Metabolomics

The field of sports medicine and performance has undergone an important transformation in the past years where the scientific approach is becoming increasingly more important for teams and athletes. Physical and physiological fitness, nutrition, fatigue and recovery, as well as injury prevention are key elements of the scientific monitoring of athletes nowadays. Many different methods are used nowadays as part of the scientific monitoring and testing of the competitive athlete. Among them, physiological and metabolic testing, biomechanical and movement assessments, GPS-based tracking systems, heart rate monitors, power meters, and training software are an integrative part of the scientific monitor program of many teams and athletes.Blood biomarkers through traditional blood analysis have been used for over three decades (mainly in Europe) to monitor athletic performance. In the same manner that different cells in the body respond to the stress of an infection or a disease, cells in athletes respond to the stress of competition and training. Nowadays, the area of blood biomarkers is an emerging field in the US offering important level of possibilities to monitor athletes. The field of metabolomics can offer a significantly higher level of blood biomarkers for sports medicine and performance monitoring.

Mountain Ultramarathon Induces Early Increases of Muscle Damage, Inflammation, and Risk for Acute Renal Injury

Purpose: This study aimed to investigate changes in muscle damage during the course of a 217-km mountain ultramarathon (MUM). In an integrative perspective, inflammatory response and renal function were also studied.

Methods: Six male ultra-runners were tested four times: pre-race, at 84 km, at 177 km, and immediately after the race. Blood samples were analyzed for serum muscle enzymes, acute-phase protein, cortisol, and renal function biomarkers.

Results: Serum creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) increased significantly throughout the race (P < 0.001, P < 0.001; P = 0.002, respectively), and effect size (ES) denoted a large magnitude of muscle damage. These enzymes increased from pre-race (132 ± 18, 371 ± 66, and 28 ± 3 U/L, respectively) to 84 km (30, 1.8, and 3.9-fold, respectively); further increased from 84 to 177 km (4.6, 2.9, and 6.1-fold, respectively), followed by a stable phase until the finish line. Regarding the inflammatory response, significant differences were found for C-reactive protein (CRP) (P < 0.001) and cortisol (P < 0.001). CRP increased from pre-race (0.9 ± 0.3 mg/L) to 177 km (243-fold), cortisol increased from pre-race (257 ± 30 mmol/L) to the 84 km (2.9-fold), and both remained augmented until the finish line. Significant changes were observed for creatinine (P = 0.03), urea (P = 0.001), and glomerular filtration rate (GFR) (P < 0.001), and ES confirmed a moderate magnitude of changes in renal function biomarkers. Creatinine and urea increased, and GFR decreased from pre-race (1.00 ± 0.03 mg/dL, 33 ± 6 mg/dL, and 89 ± 5 ml/min/1.73 m², respectively) to 84 km (1.3, 3.5, and 0.7-fold, respectively), followed by a plateau phase until the finish line.

Conclusion: This study shows evidence that muscle damage biomarkers presented early peak levels and they were followed by a plateau phase during the last segment of a 217-km MUM. The acute-phase response had a similar change of muscle damage. In addition, our data showed that our volunteers meet the risk criteria for acute kidney injury from 84 km until they finished the race, without demonstrating any clinical symptomatology.

Creatine kinase and ATPase activities in piglets fed a fungal mycotoxin co-contaminated diet: Consequences in the pathogenesis of subclinical intoxication

Creatine kinase (CK) activity, through the creatine-kinase-phosphocreatine (CK/PCr) system, provides a temporal and spatial energy buffer to maintain cellular energetic homeostasis, being responsible to provide adenosine triphosphate (ATP) to the proper function of ATPases enzymes, such as the sodium-potassium (Na⁺, K⁺-ATPase) and hydrogen (H⁺-ATPase) pumps. Thus, the aim of this study was to evaluate the involvement of CK/PCr system in the impairment of energetic homeostasis in piglets fed with a diet co-contaminated with mycotoxins, as well as the effects on ATPases enzymes. Animals were randomly divided in two groups (eight repetitions with two animals each): CON (basal diet) and MYC (mycotoxin diet; 9300 μg/kg of aflatoxins and 8000 μg/kg of fumonisins) which were feed during 15 days. Piglets that received a diet containing 300 μg/kg of aflatoxins and 8000 μg/kg of fumonisins (MYC group) presented lower body weight on days 10 and 15 of experiment when compared to control (CON group). Serum CK activity was lower on days 5, 10 and 15 of experiment in the MYC group. The same occurred for serum Na⁺, K⁺-ATPase and H⁺-ATPase activities on days 10 and 15 when compared to CON group. Moreover, serum calcium levels were superior on day 15 of experiment in the MYC group, while serum potassium and sodium levels were lower in comparison to CON group. Based on these evidences, a diet co-contaminated by aflatoxins and fumonisins inhibits serum CK activity, impairing the energetic homeostasis. This inhibition alters the activities of ATPases (Na⁺, K⁺-ATPase and H⁺-ATPase), contributing to the imbalance of Na⁺, K⁺ and Ca⁺ ionic levels. In summary, the cascade of alterations contributes directly to disease pathogenesis of piglets intoxicated by mycotoxins.

Acute effect of intermittent and continuous aerobic exercise on release of cardiac troponin T in sedentary men

BACKGROUND

Studies have shown that acute exercise can increase serum concentrations of cardiac biomarkers, including cardiac troponin T (cTnT). We investigated the acute effects of intermittent (IE) and continuous (CE) exercise at the same cardiac workload on myocardial necrosis biomarkers in sedentary men.

METHODS

Eleven sedentary healthy men aged 22.3±1.9years completed the study. The subjects were divided into two groups and performed, in random order, IE (intensity alternating between 50% (2min) and 80% (1min) HRreserve) or CE (60% HRreserve). The study was designed as a single-blinded randomised crossover trial performed on two distinct experimental days separated by a 1-week washout period. Each session consisted of 40min of aerobic exercise, either IE or CE, on a treadmill. Blood samples were taken before (PRE), immediately after (POST) and 1h after (POST-1) each exercise session.

RESULTS

hs-cTnT significantly increased immediately after exercise in both protocols and remained elevated at POST-1 (P<0.05). There was no significant difference between POST and POST-1 values(P>0.05). Neither CE nor IE caused any significant change in CK-MB (P>0.05). The results also showed that HR and RPP increased significantly following both exercise protocols (P=0.001).

CONCLUSIONS

In summary, both CE and IE results in increased serum concentrations of hs-cTnT in sedentary men. However, this increase does not seem to be caused by the irreversible death of cardiomyocytes. CE resulted in a greater hs-cTnT concentration than IE.

Greater muscle damage in athletes with ACTN3 R577X (RS1815739) gene polymorphism after an ultra-endurance race: a pilot study

In this study, we aimed to investigate the influence of ACTN3 R577X gene polymorphism on muscle damage responses in athletes competing in an ultra-endurance race. Twenty moderate to well-trained ultra-runners who had entered in an official 37.1 km adventure race (22.1 km mountain biking, 10.9 km trekking, 4.1 km water trekking, 30 m rope course, and orienteering) volunteered for the study. Blood samples were collected for genotyping and analysis of muscle protein levels before and after the race. Percentage changes (pre- to post-race) of serum myoglobin [XX = 5,377% vs. RX/RR = 1,666%; P = 0.005, effect size (ES) = 1.73], creatine kinase (XX = 836.5% vs. RX/RR = 455%; P = 0.04, ES = 1.29), lactate dehydrogenase (XX = 82% vs. RX/RR = 65%; P = 0.002, ES = 1.61), and aspartate aminotransferase (XX = 148% vs. RX/RR = 75%; P = 0.02, ES = 1.77) were significantly greater for XX than RX/RR genotypes. ES analysis confirmed a large magnitude of muscle damage in XX genotype ultra-runners. Therefore, athletes with the ACTN3 577XX genotype experienced more muscle damage after an adventure race. This suggests that ultra-runners with alpha-actinin-3 deficiency may be more susceptible to rhabdomyolysis and associated health complications during ultra-endurance competitions.