Acute variation of biochemical markers of muscle damage following a 21‐km, half‐marathon run

The Impact of Ulmus macrocarpa Extracts on a Model of Sarcopenia-Induced C57BL/6 Mice

Aging leads to tissue and cellular changes, often driven by oxidative stress and inflammation, which contribute to age-related diseases. Our research focuses on harnessing the potent anti-inflammatory and antioxidant properties of Korean Ulmus macrocarpa Hance, a traditional herbal remedy, to address muscle loss and atrophy. We evaluated the effects of Ulmus extract on various parameters in a muscle atrophy model, including weight, exercise performance, grip strength, body composition, muscle mass, and fiber characteristics. Additionally, we conducted Western blot and RT-PCR analyses to examine muscle protein regulation, apoptosis factors, inflammation, and antioxidants. In a dexamethasone-induced muscle atrophy model, Ulmus extract administration promoted genes related to muscle formation while reducing those associated with muscle atrophy. It also mitigated inflammation and boosted muscle antioxidants, indicating a potential improvement in muscle atrophy. These findings highlight the promise of Ulmus extract for developing pharmaceuticals and supplements to combat muscle loss and atrophy, paving the way for clinical applications.

Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes

Vitamin D is crucial to the health and performance of athletes. Although the exact vitamin D requirements for athletes have not been established, maintaining a 25(OH)D level of at least 40 ng/mL is considered beneficial. This randomized controlled intervention study aimed to determine whether an individual loading dose formula for vitamin D supplementation is more effective than standardized supplementation and suitable enough for athletes to meet a target value of 40 ng/mL. In a 10-week supplementation study conducted during the winter months in Germany, 90 athletes with insufficient vitamin D levels (25(OH)D < 30 ng/mL) were randomly assigned to receive either a universal dose of 2000 IU/day of vitamin D or a loading dose of 4000 IU/day, followed by a maintenance dose of 1000 IU/day. The total 25(OH)D concentration was measured from dried blood spots at three time points: at baseline, at the computed date of 40 ng/mL, and after the 10-week period. Additionally, a vitamin-D-specific questionnaire was issued. On the day when 25(OH)D blood concentrations of 40 ng/mL were calculated to prevail, the individualized group had a significantly higher 25(OH)D level than the standardized group (41.1 ± 10.9 ng/mL vs. 32.5 ± 6.4 ng/mL, p < 0.001). This study demonstrated that the examined formula is suitable enough for athletes to achieve a 25(OH)D concentration of 40 ng/mL. This indicates that a personalized approach is more effective than a one-size-fits-all approach in restoring adequate vitamin D levels in athletes.

Effects of muscle damage indicators and antioxidant capacity after interval training on the 800-m records of adolescent middle-distance runners

To examine the effect of 10-week interval training (IT) at varying intensities on serum muscle damage indicators and antioxidant capacity and determine its effect on the 800-m records of adolescent middle-distance runners. Twenty male high-school middle-distance runners were randomized between the high-intensity IT (HIIT; n=10) and the medium-intensity IT (MIIT; n=10) groups. Three sessions/week for 10 weeks (total of 30 sessions) were performed; one session of IT was for 60 min. The high and medium exercise intensities were set at 90%-95% and 60%-70% heart rate reserve (HRR), respectively. Intensity at rest was 40% HRR for both groups. Weight training was performed at 60%-70% of one repetition maximum for two sessions/week. The changes in serum muscle damage indicators and antioxidant capacity in the two groups were measured, and their effects on the 800-m records were analyzed. The 10-week training reduced serum muscle damage indicators in middle-distance runners, but only the HIIT group displayed a decrease in creatine kinase. For the change in antioxidant capacity, the two groups demonstrated no significant change in malondialdehyde (MDA), whereas the HIIT group exhibited a significant increase in super-oxide dismutase (SOD). IT also reduced the 800-m records in middle-distance running, and the effect was stronger in the HIIT group. In conclusion, 10-week HIIT can have a positive effect on muscle damage indicators, showed a significant increase in SOD as a key indicator of anti-oxidant capacity, and improved the 800-m records in middle-distance runners.

Effects of carbohydrate and protein supplement strategies on endurance capacity and muscle damage of endurance runners: A double blind, controlled crossover trial

Background

The purpose of this study is to explore the effect of carbohydrate only or carbohydrate plus protein supplementation on endurance capacity and muscle damage.

Methods

Ten recreationally active male runners (VO_2max: 53.61 ± 3.86 ml/kg·min) completed run-to-exhaustion test three times with different intakes of intervention drinks. There was a 7-day wash-out period between tests. Each test started with 60 minutes of running at 70% VO_2max (phase 1), followed by an endurance capacity test: time-to-exhaustion running at 80% VO_2max (phase 2). Participants randomly ingested either 1) 0.4 g/kg BM carbohydrate before phase 1 and before phase 2 (CHO+CHO), 2) 0.4 g/kg BM protein before phase 1 and 0.4 g/kg BM carbohydrate before phase 2 (PRO+CHO), or 3) 0.4 g/kg BM carbohydrate before phase 1 and 0.4 g/kg BM protein before phase 2 (CHO+PRO). All subjects ingested carbohydrate (CHO) 1.2 g/kg BM during phase 1, and blood samples were obtained before, immediately, and 24 h after exercise for measurements of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK), and myoglobin (MB).

Results

There was no significant difference in time to exhaustion between the three supplement strategies (CHO+CHO: 432 ± 225 s; PRO+CHO: 463 ± 227 s; CHO+PRO: 461 ± 248 s). However, ALT and AST were significantly lower in PRO+CHO than in CHO+CHO 24 h after exercise (ALT: 16.80 ± 6.31 vs. 24.39 ± 2.54 U/L; AST: 24.06 ± 4.77 vs. 31.51 ± 7.53 U/L, p < 0.05). MB was significantly lower in PRO+CHO and CHO+PRO than in CHO+CHO 24 h after exercise (40.7 ± 15.2; 38.1 ± 14.3; 64.3 ± 28.9 ng/mL, respectively, p < 0.05). CK increased less in PRO+CHO compared to CHO+CHO 24 h after exercise (404.22 ± 75.31 VS. 642.33 ± 68.57 U/L, p < 0.05).

Conclusion

Carbohydrate and protein supplement strategies can reduce muscle damage caused by endurance exercise, but they do not improve endurance exercise capacity.

Effect of 8-week high-intensity intermittent running exercise and weight training on muscle and DNA damage in male and female ski major college students

This study assessed changes in blood muscle damage indicators and DNA damage indicators in lymph and urine after 8 weeks of high-intensity intermittent running and weight training in male and female college students majoring in skiing. This study aimed to find an effective training method by investigating differences in the effectiveness between men and women. A total of 20 male and female ski major college students conducted short-term high-intensity intermittent running and weight training in the morning and afternoon, respectively, 3 days a week for 8 weeks for 24 times in total. After 8 weeks of high-intensity intermittent running and weight training, changes in DNA damage indicators in the lymph and urine and muscle damage indicators in the blood were analyzed. The creatine kinase level significantly differed at rest pre-graded exercise testing (GXT) and 60 min of recovery post-GXT after training from that before training between the male and female groups. Although lactate dehydrogenase (LDH) levels decreased in both groups over time, no significant differences in LDH were found between the two groups. Second, DNA 8-hydroxydeoxyguanosine (8-OHdG) in the lymph was significantly different between the two groups at rest pre-GXT and 60 min of recovery post-GXT. 8-OHdG in the urine was significantly lower in the female group only at 60 min of recovery post-GXT. Partial sex differences were found in the reduction of muscle damage and DNA damage after 8 weeks of high-intensity intermittent running and weight training.

Hsp90 as a Myokine: Its Association with Systemic Inflammation after Exercise Interventions in Patients with Myositis and Healthy Subjects

Compelling evidence supports the health benefits of physical exercise on the immune system, possibly through the molecules secreted by the skeletal muscles known as myokines. Herein, we assessed the impact of exercise interventions on plasma Heat shock protein 90 (Hsp90) levels in 27 patients with idiopathic inflammatory myopathies (IIM) compared with 23 IIM patients treated with standard-of-care immunosuppressive therapy only, and in 18 healthy subjects undergoing strenuous eccentric exercise, and their associations with the traditional serum markers of muscle damage and inflammation. In contrast to IIM patients treated with pharmacotherapy only, in whom we demonstrated a significant decrease in Hsp90 over 24 weeks, the 24-week exercise program resulted in a stabilization of Hsp90 levels. These changes in Hsp90 levels were associated with changes in several inflammatory cytokines/chemokines involved in the pathogenesis of IIM or muscle regeneration in general. Strenuous eccentric exercise in healthy volunteers induced a brief increase in Hsp90 levels with a subsequent return to baseline levels at 14 days after the exercise, with less pronounced correlations to systemic inflammation. In this study, we identified Hsp90 as a potential myokine and mediator for exercise-induced immune response and as a potential biomarker predicting improvement after physiotherapy in muscle endurance in IIM.

Effects of Alkaline-Reduced Water on Exercise-Induced Oxidative Stress and Fatigue in Young Male Healthy Adults

Regular physical activity confers health benefits and improves the general quality of life. Recently, alkaline-reduced water (ARW) consumption has garnered increasing attention in the field of sports. ARW effectively inhibits the oxidative stress generated in cells during high-intensity exercises; however, whether it exerts similar effects during exhaustive exercises remains unknown. This study was designed as a randomized, controlled, crossover, double-blind clinical trial with a single intervention of ARW intake (pH 9.5, 10 mL/kg body weight) after intense exercise. The participants were divided into two groups, wherein they consumed either purified water (PW group) or ARW (ARW group). Blood samples were collected before exercise, immediately after exercise, and 15 min after drinking water. The serum levels of oxidative stress markers and fatigue markers were determined. The results showed that ROS (p < 0.01) and NO levels (p < 0.001) were significantly decreased after ARW intake, and the reduction was more pronounced than that in the PW group. Interestingly, the increase in GPx and MDA levels was mediated by ARW intake (both p < 0.05) after exercise. The levels of fatigue markers, such as lactate (p < 0.001), lactate dehydrogenase (p < 0.001), and phosphate (p < 0.001), were significantly reduced in both groups, with ARW intervention showing more decreased markers. The correlation analysis results showed that ARW may help maintain homeostatic conditions for ROS, antioxidant systems, and fatigue markers. These findings indicate that ARW consumption is effective in reducing oxidative stress and fatigue following exhaustive exercise and that ARW could be used as an antioxidant and anti-fatigue supplement after exhaustive physical exercise.

Basal Values of Biochemical and Hematological Parameters in Elite Athletes

The purpose of this study was to show how continuous exercise affects the basal values of biochemical and hematological parameters in elite athletes. A total of 14,010 samples (male = 8452 and female = 5558 (March 2011–March 2020)) from 3588 elite athletes (male = 2258 and female = 1330, mean age 24.9 ± 6.9 vs. 24.1 ± 5.5 years, respectively) from 32 sport modalities, were studied over 9 years to check the variation of basal biochemical and hematological parameter values. There were differences seen in the basal values of creatine kinase (CK), urea, creatinine, aspartate transaminase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), potassium, total bilirubin, and eosinophil percentage compared to reference population data. However, other analytes showed narrow ranges of variation like glucose, total protein, albumin, sodium, hemoglobin, mean cell volume (MCV), and platelet count. Exercise produces changes in biochemical and hematological basal values of athletes compared to the general population, with the greatest variation in CK, but AST, ALT, LDH, potassium, and total bilirubin (TBil) show high values in serum, only with a wider distribution of values. The data here reflects the effect of exercise on biochemical and hematological parameter baseline ranges in elite athletes. As clinical laboratories use reference intervals to validate clinical reports, these “pseudo” reference intervals should be used when validating laboratory reports.

Benefits on Hematological and Biochemical Parameters of a High-Intensity Interval Training Program for a Half-Marathon in Recreational Middle-Aged Women Runners

(1) Background: half-marathon races are popular among recreational runners, with increases in participation among middle-aged and women. We aimed to determine the effects of two half-marathon training programs on hematological and biochemical markers in middle-aged female recreational runners; (2) Methods: ten women (40 ± 7 years) followed moderate intensity continuous training (MICT), based on running volume below 80% V˙O₂max, and another ten women followed high intensity interval training (HIIT) at 80%–100% V˙O₂max, with less volume, and combined with eccentric loading exercise. Hematology, plasma osmolality, and plasma markers of metabolic status, muscle damage, inflammatory, and oxidative stress were measured before (S1) and after (S2) training and 24 h after the half-marathon (S3); (3) Results: both training programs had similar moderate effects at S2. However, the acute response at S3 induced different alterations. There was a greater decrease in cholesterol and triglyceride levels in MICT and reductions in markers of damage and inflammation in HIIT. Greater variability in some plasma markers at S3 in MICT suggests that there is inter-individual variability in the response to training; (4) Conclusions: HIIT led to better adaptation to the competition maybe because of the repeated exposure to higher oxygen consumption and eccentric loading exercise.

Training Load Measures and Biomarker Responses during a 7-Day Training Camp in Young Cyclists-A Pilot Study

Background and Objectives: During intense training periods, there is a high need to monitor the external and especially the internal training load in order to fine-tune the training process and to avoid overreaching or overtraining. However, data on stress reactions, especially of biomarkers, to high training loads in children and youth are rare. Therefore, in this study, we aimed to investigate the training load of youth athletes during a training camp using a multilevel approach. Materials and Methods: Six trained youth male cyclists performed a 7-day preseason training camp. To investigate the internal training load, every morning, minimally invasive “point-of-care testing” (POCT) devices were used to analyze the following biomarkers: creatine kinase (CK), blood urea nitrogen (BUN), albumin (Alb), bilirubin (Bil), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total protein (TP). Additionally, data of training load measures (HR: heart rate, RPE: rating of perceived exertion, sRPE: session-RPE, TRIMP: training impulse, intensity (RPE:HR), and load (sRPE:TRIMP) ratios), self-perception (person’s perceived physical state, questionnaires on muscle soreness, and sleep quality), and measures of the autonomic nervous system (resting heart rate, heart rate variability) were collected. Two days before and after the training camp, subjects performed performance tests (Graded Exercise Test, Wingate Anaerobic Test, Counter Movement Jump). Results: Primarily, the biomarkers CK, BUN, and Alb, as well as the self-perception showed moderate to large load-dependent reactions during the 7-day training camp. The biomarkers returned to baseline values two days after the last training session. Power output at lactate threshold showed a small increase, and no changes were found for other performance parameters. Conclusions: The study suggests that a multilevel approach is suitable to quantify the internal training load and that different parameters can be used to control the training process. The biomarkers CK, BUN, and Alb are suitable for objectively quantifying the internal training load. The self-perception provides additional subjective information about the internal training load.

Effects of branched-chain amino acid supplement on knee peak torque and indicators of muscle damage following isokinetic exercise-induced delayed onset muscle soreness

[Purpose]

This study aimed to investigate the effects of branched-chain amino acid (BCAA) supplement on delayed onset muscle soreness (DOMS) by analyzing the maximum muscle strength and indicators of muscle damage.

[Methods]

Twelve men with majors in physical education were assigned to the BCAA group and placebo group in a double-blinded design, and repeated measurements were conducted. DOMS was induced with an isokinetic exercise. Following BCAA administration, the changes in the knee extension peak torque, flexion peak torque, aspartate aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LDH) concentrations were analyzed. The maximum knee muscle strength was measured at the baseline (pre-D0) following BCAA administration for 5 days before exercise (-D5, -4D, -3D, -2D, -1D). In contrast, the post-treatment measurements (D3) were recorded after BCAA administration for 3 days (post-D0, D1, D2). Blood samples were obtained before (pre-D0), immediately after (post-D0), 24 h (D1), 48 h (D2), and 72 h (D3) after the exercise to analyze the indicators of muscle strength. BCAA was administered twice daily for 8 days (5 days and 3 days before inducing DOMS and during the experimental period, respectively).

[Results]

There was no difference in the flexion peak torque between the groups. However, the BCAA group showed a significantly higher extension peak torque at D3 (second isokinetic exercise), compared to the placebo group (p<.05). There was no difference in AST changes between the groups. Nonetheless, the CK and LDH were significantly reduced in the BCAA group, compared to the placebo group. There was no correlation between the extension peak torque and flexion peak torque. However, the CK and LDH increased proportionately in DOMS. Moreover, their concentrations significantly increased with a decreasing peak torque (p<.01).

[Conclusion]

An exercise-induced DOMS results in a decrease in the peak torque and a proportional increase in the CK and LDH concentrations. Moreover, the administration of BCAA inhibits the reduction of the extension peak torque and elevation of CK and LDH concentrations. Therefore, BCAA might be administered as a supplement to maintain the muscle strength and prevent muscle damage during vigorous exercises that may induce DOMS in sports settings.

Changes in Fatigue Recovery and Muscle Damage Enzymes after Deep-Sea Water Thalassotherapy

The purpose of this study was to verify the effect of deep-sea water thalassotherapy (DSWTT) on recovery from fatigue and muscle damage. The same exercise program is conducted in general underwater and deep-sea water to confirm the characteristics of deep-sea water through fatigue recovery and muscle damage enzymes. A total of 30 male college students were studied, including 10 belonging to the control group (CG), 10 in the water exercise group (WEG), and 10 in the deep-sea water exercise group (DSWEG). The DSWTT treatment consists of three components—preheating, treatment, and cooling—and the DSWTT program stretches and massages the entire upper body, lower body, back, and the entire body for a total of 25 min in a deep-sea tank. After the DSWTT program, blood tests were conducted to confirm the level of fatigue-related parameters and muscle damage enzymes. Fatigue-related parameters including glucose, lactate, ammonia, and lactate dehydrogenase (LDH), and the levels of muscle damage enzymes such as creatinine kinase (CK) and aspartate aminotransferase (AST) were measured. The results revealed that fatigue had a primary effect (p < 0.001) and exhibited strongly significant interaction (p < 0.001) with lactate, ammonia, and LDH levels, whereas the glucose level remained unchanged. The post hoc results showed a significant decrease in these parameters among DSWEG compared to CG and WEG (p < 0.01). Muscle damage enzymes showed a main effect (p < 0.001) and significant interaction (p < 0.001) with CK and AST (p < 0.001). The post hoc results showed a significant decrease in DSWEG compared with CG and WEG (p < 0.01). In conclusion, the DSWTT program applied to this study showed significant effects on muscle fatigue and muscle damage recovery. When the DSWTT program is applied in hot springs, it can have a positive effect on muscle fatigue and muscle damage recovery and can contribute to improving national health and quality of life. Further studies are needed to investigate DSWTT programs with various research subjects at different program temperatures, exercise times, and frequencies of treatment and exercise.

Effect of mountain ultramarathon distance competition on biochemical variables, respiratory and lower-limb fatigue

The study aimed at assessing the acute physiological effects of running a 65-km vs a 107-km mountain ultramarathon. Nineteen athletes (15 males and 4 females) from the shorter race and forty three athletes (26 males and 17 females) from the longer race were enrolled. Body weight, respiratory and lower limb strength were assessed before and after the race. Blood samples were obtained before, after and 24-h post-race. Body weight loss did not differ between races. A decrease in squat jump height (p<0.01; d = 1.4), forced vital capacity (p<0.01; d = 0.5), forced expiratory volume in 1 s (p<0.01; d = 0.6), peak inspiratory flow (p<0.01; d = 0.6) and maximal inspiratory pressure (p<0.01; d = 0.8) was observed after the longer race; while, after the shorter race only maximal inspiratory pressure declined (p<0.01; d = 0.5). Greater post-race concentrations of creatine kinase (p<0.01; d = 0.9) and C-reactive protein (p<0.01; d = 2.3) were observed following the longer race, while high-sensitivity cardiac troponin was higher after the shorter race (p<0.01; d = 0.3). Sodium decreased post-competition only after the shorter race (p = 0.02; d = 0.6), while creatinine increased only following the longer race (p<0.01; d = 1.5). In both groups, glomerular filtration rate declined at post-race (longer race: p<0.01, d = 2.1; shorter race: p = 0.01, d = 1.4) and returned to baseline values at 24 h post-race. In summary, expiratory and lower-limb fatigue, and muscle damage and inflammatory response were greater following the longer race; while a higher release of cardiac troponins was observed after the shorter race. The alteration and restoration of renal function was similar after either race.

Laboratory medicine: health evaluation in elite athletes

The need to evaluate the health status of an athlete represents a crucial aim in preventive and protective sports science in order to identify the best diagnostic strategy to improve performance and reduce risks related to physical exercise. In the present review we aim to define the main biochemical and haematological markers that vary significantly during and after sports training to identify risk factors, at competitive and professional levels and to highlight the set up of a specific parameter's panel for elite athletes. Moreover, we also intend to consider additional biomarkers, still under investigation, which could further contribute to laboratory sports medicine and provide reliable data that can be used by athlete's competent staff in order to establish personal attitudes and prevent sports injuries.

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.

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.

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.

Diagnostic biomarkers of muscle injury and exertional rhabdomyolysis

Early recognition of muscle injury, up to development of exertional rhabdomyolysis (ER), is essential for many clinical and practical reasons, such as planning the suitable period of recovery and deciding an appropriate time for return to exercise. Albeit magnetic resonance imaging (MRI) remains the reference technique for assessing muscle injuries, and ultrasonography (US) may be a complementary approach for easy, inexpensive and fast screening, the potential drawbacks of both techniques may be overcome by some laboratory tests, which may help guiding both diagnostic reasoning and clinical decision making. Current evidence attest that creatine kinase remains the most validated test across the clinical spectrum of muscles injuries, as its measurement may be helpful for screening subjects with suggestive signs and symptoms, its concentration substantially reflects the amount of injured muscle and its kinetics appears suitable, combined with clinics and results of imaging testing, for making decisions on return to exercise. Relatively low cost and widespread availability are additional advantages of this test. In athletes with ER, myoglobin assessment may provide adjunctive useful information, due to high predictive value for development of acute kidney injury. Regarding other historical biomarkers, namely aldolase and lactate dehydrogenase, the kinetics, correlation with injury severity, laboratory standardization and availability make their measurement unsuitable and redundant. Some innovative biomarkers have also been tested in recent years, including fatty acid-binding proteins and carbonic anhydrase III, myosin light chain 3 and muscle micro RNAs. However, their clinical effectiveness, standardization, availability in clinical laboratories and costs are still regarded as major drawbacks.

rt-PA with remote ischemic postconditioning for acute ischemic stroke

Objective

To investigate the feasibility and safety of remote ischemic postconditioning (RIPC) in acute ischemic stroke patients after intravenous recombinant tissue plasminogen activator (rt‐PA) thrombolysis (IVT).

Methods

We performed a pilot randomized trial involving acute ischemic stroke patients with IVT. The patients were randomized 1:1 to receive RIPC or standard medical therapy. In the RIPC group, the participants underwent instant RIPC within 2 h of IVT, followed by repeated RIPC therapy for 7 days. The feasibility end point was the completion of RIPC and time from the first RIPC to finishing IVT in the RIPC group. The safety end point included tissue and neurovascular injury resulting from RIPC, changes in vital signs, level of plasma myoglobin, any hemorrhagic transformation, and other adverse events.

Results

Thirty patients (15 RIPC and 15 Control) were recruited after IVT. The mean age was 65.7 ± 10.2 years, with a National Institutes of Health Stroke Scale (NIHSS) score of 6.5 (4.0–10.0). The completion rate for RIPC was 97.0%. The mean time from first RIPC to completing IVT was 66.0 (25.0–75.0) min in the RIPC group. One case of hemorrhagic transformation was observed in the RIPC group. No significant difference was found in the level of myoglobin between the two groups (P > 0.05).

Interpretation

RIPC is effective and safe for AIS patients after intravenous rt‐PA thrombolysis.

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.

Endurance exercise causes adverse changes in some hematological and physiobiochemical indices in ponies under high altitude stress condition

The ponies have immense relevance for logistic support for civil population and troops in hilly and high altitude areas. There is no information on specific biomarkers of endurance performance under high altitude stress condition, which could be supportive in the identification of elite ponies for deployment at high altitude. Therefore, the present study was conducted to evaluate the physiological responses, hematological, biochemical, metabolic, and antioxidant biomarker during endurance exercise in ponies at high altitude. For this study, total 5 mares were put on endurance exercise at 4–6 m/sec speed for 30 min on 30 m track situated at 3,500 m altitude for 28 days period. The result showed a significant change in physiological responses, and some hematological, biochemical, metabolic and antioxidant parameters viz. glutathione peroxidase, creatinine kinase-MB, lactic acid, total protein, glucose, hexokinase, cortisol, and interleukin-6 level at different phase of endurance exercise. In conclusion, this study showed the alteration in physiological responses and some hematological and physio-biochemical metabolic parameters during the endurance exercise. Hence, these parameters could be considered as biomarkers for evaluation of endurance performance in ponies at high altitude before putting them under load carrying deployment.

Pacing in a 94-year-old runner during a 6-hour run

It is well known that elderly people up to 90 years of age are able to finish a marathon. We have no knowledge, however, how runners at the age of 90 years or older pace during a long run. In this case report, we describe the pacing of a 94-year-old man competing in a 6-hour run in order to prepare for a marathon at the age of 95 years in category M95. In the “6-Stunden-Lauf ” held in Brugg, Switzerland, participants have to run as many laps of 0.934 km as possible on a completely flat circuit within 6 hours to achieve as many kilometers as possible. Before and after the competition we measured body weight, percentage of body fat, fat-free mass and percentage of body water using a bioelectrical impedance scale. On the day before the start, 24 hours after the finish and then every 24 hours for the following 4 days, capillary blood samples at a fingertip were drawn to determine hemoglobin, hematocrit, leukocytes, platelets, C-reactive protein, creatine kinase, creatinine and potassium and sodium. The runner achieved 26 laps during the 6 hours, equal to 24.304 km. Lap times increased continuously and running speed decreased nearly linearly. A large main effect of time point (hours) of the race on running speed was observed (p=0.015, η²=0.48) with running speed being slower in the last hour than that in the first hour (3.5±1.4 km/h versus 5.3±0.4 km/h). Body mass decreased by 0.6%, percent body fat by 1.4% and fat-free mass by 0.7%. During recovery, hemoglobin, hematocrit and the number of thrombocytes increased, whereas the number of leukocytes remained unchanged. C-reactive protein was highest on day 1 after the race and decreased by day 4 nearly to zero. Creatine kinase was slightly elevated pre-race, highest the day after the race and remained slightly elevated until day 4. Creatinine and potassium were increased pre-race but returned to normal values during recovery. Sodium remained within normal values on all days. Based on the linear decrease in running speed, we extrapolated for the marathon distance to run a marathon in age group M95 (i.e., male marathoners aged 95–99 years). In the worst-case scenario (i.e., the athlete develops maximal fatigue), he would stop the race before 40 km, in the best scenario (i.e., the athlete develops minimal fatigue), he would achieve an overall race time of ~8.3 hours and in the most probable scenario (i.e., the athlete can continue in the same manner), the final race time will be longer than 11 hours.

Biochemical, physiological, and performance response of a functional watermelon juice enriched in L-citrulline during a half-marathon race

Background: Watermelon is a rich natural source of l-citrulline. This non-essential amino acid increases exercise performance.

Objective: Evaluate the effect of Fashion watermelon juice enriched in l-citrulline (CWJ) (3.45 g per 500 mL) in physical performance and biochemical markers after a half-marathon race.

Design: A randomised, double blind, crossover design where 2 h after drinking 500 mL of CWJ or placebo (PLA, beverage without l-citrulline) amateur male runners performed two half-marathon races. Jump height, heart rate and rating of perceived exertion were evaluated before and after the races. Moreover, muscle soreness and plasma markers of muscle damage and metabolism were evaluated for 72 h after the races.

Results: Muscle soreness perception was significantly lower from 24 to 72 h after the race with CWJ beverage. Immediately after the races, runners under CWJ condition showed plasma lactate and glucose concentrations significantly lower and higher lactate dehydrogenase and l-arginine concentration than runners under PLA. A maintenance of jump heights after the races under CWJ supplementation was found, decreasing significantly with PLA.

Conclusion: A single Fashion watermelon juice enriched in l-citrulline dose diminished muscle soreness perception from 24 to 72 h after the race and maintained lower concentrations of plasma lactate after an exhausting exercise.

Consumption of Watermelon Juice Enriched in l-Citrulline and Pomegranate Ellagitannins Enhanced Metabolism during Physical Exercise

l-Citrulline is a nonessential amino acid precursor of arginine and indirectly a precursor of nitric oxide (NO), which is a vasodilator and increases mitochondrial respiration. On the other hand, the antioxidant pomegranate ellagitannins are precursors of urolithin A, which has been associated with mitophagy and increased muscle function. To elucidate if a single dose of watermelon enrichment with these compounds could have a positive effect after high-intensity exercise (eight sets of eight repetitions of half-squat exercise), a double-blind randomized crossover in vivo study was performed in healthy male subjects (n = 19). Enrichment juices maintained basal levels of blood markers of muscle damage, such as lactate dehydrogenase and myoglobin, and showed a significant maintenance of force during the exercise and a significant decrease in the rating of perceived exertion and muscle soreness after exercise. A positive effect was observed between l-citrulline and ellagitannins, improving the ergogenic effect of watermelon juice.

Plasma Actin, Gelsolin and Orosomucoid Levels after Eccentric Exercise

The present study investigated the acute effect of eccentric exercise on blood plasma actin, gelsolin (GSN) and orosomucoid (AGP) levels in untrained and moderately trained individuals, and their correlation with exercise induced muscle damage (EIMD) markers (CK, intensity of muscle soreness and maximal voluntary contraction torque deficit). Healthy physical education students (6 untrained, 12 moderately trained) participated in this research. Actin, GSN, AGP and CK levels were measured in blood plasma at baseline, immediately, 1 h, 6 h and 24 h post-exercise comprising 90 eccentric quadriceps contractions performed on a dynamometer. There was significant time main effect for GSN, AGP, CK and significant difference was found between baseline and the lowest value of post-exercise GSN (p < 0.05), as well as baseline and the highest value of post-exercise AGP (p < 0.05). Relationships were found between GSN levels and other indirect EIMD markers (between all GSN levels at post-exercise and CK activity at 6 h, p < 0.05; GSNMIN and muscle soreness at post-exercise, p < 0.04), GSN and AGP; however, actin did not correlate at any time points with GSN. Actin, GSN, AGP and CK responses after eccentric exercise do not seem sensitive to training status. The plasma actin level is used as an indicator of injury, however, our results suggest that it is not an accurate marker of EIMD, while plasma GSN concentrations show a better relationship with EIMD and the post-exercise inflammatory process. The elevated plasma AGP and the correlation between GSN and AGP seem to be promising for assessment of exercise-induced muscle injury.

Troponin and exercise

Cardiac troponins are the preferred biomarkers in diagnostic of myocardial infarction, but these markers also can rise in response to exercise. Multiple studies have assessed troponins post-exercise, but the results have varied and there have been disagreements about the mechanism of troponin release. The aim of this paper was to review the literature, and to consider factors and mechanisms regarding exercise-induced increase of troponin. 145 studies were found after a search in pubmed and inclusion of additional articles found in the reference list of the first articles. Results showed that troponin rises in 0-100% of subjects after prolonged heavy exercise like marathon, but also after short-term and intermittent exercise like 30min of running and basketball. The variation can be due to factors like intensity, age, training experience, variation in sample size, blood sample timing and troponin assay. The pattern of troponin level post-exercise corresponds to release from the cytosolic compartment of cardiomyocytes. Increased membrane permeability might be caused by production of reactive oxygen species or alterations in calcium, pH, glucose/fat metabolism or in communication between integrins. Other suggested mechanisms are increased cardiovascular stress, inflammation, vasculitis, release of troponin degradation products in "blebs", dehydration, impaired renal clearance and expression of cardiac troponin in skeletal muscle. It can be concluded that both heavy and light exercise may cause elevated troponin, which have to be considered when patient are suspected to have a myocardial infarction. Several factors probably influence post-exercise levels of troponin, but the mechanism of release is most likely physiologic.

The baseline serum value of α-amylase is a significant predictor of distance running performance

BACKGROUND

This study was planned to investigate whether serum α-amylase concentration may be associated with running performance, physiological characteristics and other clinical chemistry analytes in a large sample of recreational athletes undergoing distance running.

METHODS

Forty-three amateur runners successfully concluded a 21.1 km half-marathon at 75%-85% of their maximal oxygen uptake (VO2max). Blood was drawn during warm up and 15 min after conclusion of the run.

RESULTS

After correction for body weight change, significant post-run increases were observed for serum values of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, creatine kinase (CK), iron, lactate dehydrogenase (LDH), triglycerides, urea and uric acid, whereas the values of body weight, glomerular filtration rate, total and low density lipoprotein-cholesterol were significantly decreased. The concentration of serum α-amylase was unchanged. In univariate analysis, significant associations with running performance were found for gender, VO2max, training regimen and pre-run serum values of α-amylase, CK, glucose, high density lipoprotein-cholesterol, LDH, urea and uric acid. In multivariate analysis, only VO2max (p=0.042) and baseline α-amylase (p=0.021) remained significant predictors of running performance. The combination of these two variables predicted 71% of variance in running performance. The baseline concentration of serum α-amylase was positively correlated with variation of serum glucose during the trial (r=0.345; p=0.025) and negatively with capillary blood lactate at the end of the run (r=-0.352; p=0.021).

CONCLUSIONS

We showed that the baseline serum α-amylase concentration significantly and independently predicts distance running performance in recreational runners.

Impact of different running distances on muscle and lymphocyte DNA damage in amateur marathon runners

[Purpose] The aim of this study was to investigate the impact of different marathon running distances (10 km, 21 km, and 42.195 km) on muscle and lymphocyte DNA damage in amateur marathon runners. [Subjects and Methods] Thirty male amateur runners were randomly assigned to 10 km, 21 km, and 42 km groups, with 10 subjects in each group. Blood samples were collected before and after the races and on the 3rd day of recovery to examine levels of muscle damage (creatine kinase and lactate dehydrogenase) and lymphocyte DNA damage (DNA in the tail, tail length, and tail moment). [Results] Serum creatine kinase, serum lactate dehydrogenase, and tail moment were significantly higher after the races compared with before the races in all groups. In addition, the 42 km group showed significantly higher levels of creatine kinase, lactate dehydrogenase, and tail moment than the 10 km and 21 km groups after the races. [Conclusion] Strenuous endurance exercise can cause muscle and lymphocyte DNA damage, and the extent of such damage can increase as running distance increases.

Chronic physical stress differences between genders in a military training on the Amazon jungle

This study aimed to investigate the gender difference in the manifestation of physical stress in a strenuous military training on Amazon jungle, using alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) markers, measured before and after an adaptation to jungle training. The sample consisted of 49 military volunteers, 35 male and 14 female, recently moved to the Amazon region. All plasma levels rose after the training. Serum ALT (male and female) and AST (male and female), although borderline, remained within normal limits. Already plasma levels of CK (both male and female) and LDH (male and female) largely exceeded the normal range. The average of all markers listed in female gender remained below the levels of the male gender. However, significant differences in biomarkers ALT, AST and CK between genders were found. The study points out that, in a jungle environment, biometric markers ALT, AST, CK and LDH are efficient for monitoring chronic physical stress in both genders, when used in combination. The influence of the weather on the occurrence of physical stress in unacclimated people of both genders, and the lower responses in the levels of ALT, AST, LDH and CK in females were discussed basing on the scientific literature.

Does a run/walk strategy decrease cardiac stress during a marathon in non-elite runners?

OBJECTIVES

Although alternating run/walk-periods are often recommended to novice runners, it is unclear, if this particular pacing strategy reduces the cardiovascular stress during prolonged exercise. Therefore, the aim of the study was to compare the effects of two different running strategies on selected cardiac biomarkers as well as marathon performance.

DESIGN

Randomized experimental trial in a repeated measure design.

METHODS

Male (n=22) and female subjects (n=20) completed a marathon either with a run/walk strategy or running only. Immediately after crossing the finishing line cardiac biomarkers were assessed in blood taken from the cubital vein. Before (-7 days) and after the marathon (+4 days) subjects also completed an incremental treadmill test.

RESULTS

Despite different pacing strategies, run/walk strategy and running only finished the marathon with similar times (04:14:25±00:19:51 vs 04:07:40±00:27:15 [hh:mm:ss]; p=0.377). In both groups, prolonged exercise led to increased B-type natriuretic peptide, creatine kinase MB isoenzyme and myoglobin levels (p<0.001), which returned to baseline 4 days after the marathon. Elevated cTnI concentrations were observable in only two subjects. B-type natriuretic peptide (r=-0.363; p=0.041) and myoglobin levels (r=-0.456; p=0.009) were inversely correlated with the velocity at the individual anaerobic threshold. Run/walk strategy compared to running only reported less muscle pain and fatigue (p=0.006) after the running event.

CONCLUSIONS

In conclusion, the increase in cardiac biomarkers is a reversible, physiological response to strenuous exercise, indicating temporary stress on the myocyte and skeletal muscle. Although a combined run/walk strategy does not reduce the load on the cardiovascular system, it allows non-elite runners to achieve similar finish times with less (muscle) discomfort.

Cardiac Damage Biomarkers Following a Triathlon in Elite and Non-elite Triathletes

The purpose of the present study was to investigate cardiac damage biomarkers after a triathlon race in elite and non-elite athlete groups. Fifteen healthy men participated in the study. Based on performance, they were divided into elite athlete group (EG: n=7) and non-elite athlete group (NEG: n=8). Participants' blood samples were obtained during four periods: before, immediately, 2 hours and 7 days after finishing the race. creatine kinase (CK), creatine kinase-myoglobin (CK-MB), myoglobin, and lactate dehydrogenase (LDH) were significantly increased in both groups immediately after, and 2 hours after finishing the race (p<.05). CK, CK-MB, and myoglobin were completely recovered after 7 days (p<.05). Hematocrit (Hct) was significantly decreased in both groups (p<.05) 7 days after the race. LDH was significantly decreased in the EG (p<.05) only 7 days after the race. Homoglobin (Hb) was significantly decreased in the NEG (p<.05) only 2 hours after the race. Although cardiac troponin T (cTnT) was significantly increased in the EG but not in the NEG 2hours after the race (p<.05), there was no group-by-time interaction. cTnT was completely recovered in both groups 7 days after the race. In conclusion, cardiac damage occurs during a triathlon race and, is greater in elite than in non-elite. However, all cardiac damage markers return to normal range within 1 week.

A Pilot Study on Pain and the Upregulation of Myoglobin through Low-frequency and High-amplitude Electrical Stimulation-induced Muscle Contraction

[Purpose] It is well known that, in both in vivo and in vitro tests, muscle fatigue is produced by severe exercise, electrical stimulation, and so on. However, it is not clear whether or not low-frequency and high-amplitude modulation specifically affects serum myoglobin or urine myoglobin. The purpose of the present study was to determine the effect of low-frequency and high-amplitude modulation on serum myoglobin and urine myoglobin. [Methods] The study used whole blood samples and urine produced over 24 hours from the thirteen healthy subjects. [Results] There was a significant increase in serum myoglobin following electrical stimulation at a frequency of 10 Hz compared with the control group. Furthermore, within 24 hours, urine myoglobin also showed a significant increase for the test volunteers subjected to electrical stimulation at the 10 Hz frequency compared with the control group. However, there were no significant differences in the concentrations of hematologic results in subjects treated with electrical stimulation. [Conclusion] These results suggest that increased myoglobin related to muscle fatigue from electrical stimulation, particularly with a current of 10 Hz combined with a high-amplitude, may be partially related to increased muscle damage.

Leukocytosis, muscle damage and increased lymphocyte proliferative response after an adventure sprint race

The effect of an adventure sprint race (ASR) on T-cell proliferation, leukocyte count and muscle damage was evaluated. Seven young male runners completed an ASR in the region of Serra do Espinhaço, Brazil. The race induced a strong leukocytosis (6.22±2.04×10³ cells/mm³ before vs 14.81±3.53×10³ cells/mm³ after the race), marked by a significant increase of neutrophils and monocytes (P<0.05), but not total lymphocytes, CD3⁺CD4⁺ or CD3⁺CD8⁺ cells. However, the T-cell proliferative response to mitogenic stimulation was increased (P=0.025) after the race, which contradicted our hypothesis that ASR, as a high-demand competition, would inhibit T-cell proliferation. A positive correlation (P=0.03, r=0.79) was observed between the proliferative response of lymphocytes after the race and the time to complete the race, suggesting that the proliferative response was dependent on exercise intensity. Muscle damage was evident after the race by increased serum levels of aspartate amino transferase (24.99±8.30 vs 50.61±15.76 U/L, P=0.003). The results suggest that humoral factors and substances released by damaged muscle may be responsible for lymphocyte activation, which may be involved in muscle recovery and repair.

Physical activity - an important preanalytical variable

The concentration of several biochemical and hematological biomarkers is strongly influenced by a number of preanalytical variables. Several lines of evidence attest that short, middle, and long-term exercise, as well as the relative intensity of physical effort (from mild to strenuous), may influence a broad array of laboratory variables. The amount of extracellular release and clearance from blood of most of these biomarkers is markedly influenced by the biological characteristics of the molecule(s), level of training, type, intensity and duration of exercise, and time of recovery after training. It is hence noteworthy that test results that fall outside the conventional reference ranges in athletes not only may reflect the presence of a given disease, but may frequently mirror an adaptation to regular training or changes that have occurred during and/or following strenuous exercise, and which should be clearly acknowledged to prevent misinterpretation of laboratory data. The aim of this narrative review is to provide an update about the most significant changes of some biochemical and hematological biomarkers in response to physical exercise, for appropriate interpretation of these changes in the context of physically active subjects.

Serum S100B level increases after running but not cycling exercise

The objective of this study was to investigate the effect of running versus cycling exercises upon serum S100B levels and typical markers of skeletal muscle damage such as creatine kinase (CK), aspartate aminotransferase (AST) and myoglobin (Mb). Although recent work demonstrates that S100B is highly expressed and exerts functional properties in skeletal muscle, there is no previous study that tries to establish a relationship between muscle damage and serum S100B levels after exercise. We conducted a cross-sectional study on 13 male triathletes. They completed 2 submaximal exercise protocols at anaerobic threshold intensity. Running was performed on a treadmill with no inclination (RUN) and cycling (CYC) using a cycle-simulator. Three blood samples were taken before (PRE), immediately after (POST) and 1 h after exercise for CK, AST, Mb and S100B assessments. We found a significant increase in serum S100B levels and muscle damage markers in RUN POST compared with RUN PRE. Comparing groups, POST S100B, CK, AST and Mb serum levels were higher in RUN than CYC. Only in RUN, the area under the curve (AUC) of serum S100B is positively correlated with AUC of CK and Mb. Therefore, immediately after an intense exercise such as running, but not cycling, serum levels of S100B protein increase in parallel with levels of CK, AST and Mb. Additionally, the positive correlation between S100B and CK and Mb points to S100B as an acute biomarker of muscle damage after running exercise.

Alterations of Neuromuscular Function after the World's Most Challenging Mountain Ultra-Marathon

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n = 15; finish time  = 122.43 hours ±17.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n = 8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean ± SD maximal voluntary contraction force declined significantly at Mid- (−13±17% and −10±16%, P<0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (−24±13% and −26±19%, P<0.01) with alteration of the central activation ratio (−24±24% and −28±34% between Pre- and Post-, P<0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: −18±18% and PF: −20±15%, P<0.01) and peak twitch (KE: −33±12%, P<0.001 and PF: −19±14%, P<0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (3719±3045 Ul·¹), lactate dehydrogenase (1145±511 UI·L⁻¹), C-Reactive Protein (13.1±7.5 mg·L⁻¹) and myoglobin (449.3±338.2 µg·L⁻¹) were higher (P<0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protective anticipatory pacing strategy during the first half of MUM and sleep deprivation in the second half.

Continuous and intermittent running to exhaustion at maximal lactate steady state: neuromuscular, biochemical and endocrinal responses

OBJECTIVE

The aim of the present study was to characterize the neuromuscular, biochemical, and endocrinal responses from a running to exhaustion mode at the maximal lactate steady state intensity during continuous and intermittent protocols.

DESIGN

Pre-post test measures.

METHODS

Twelve athletes performed an incremental treadmill test, several constant speed tests to determine the maximal lactate steady state at continuous and intermittent (5:1 ratio) models and two randomized tests until exhaustion at such intensities. Knee extension torque and blood sampling were collected before and immediately after the time to exhaustion tests.

RESULTS

The results showed a significant decrement (∼15%) in torque production after time to exhaustion tests for both exercise models. In addition to neuromuscular impairment, an acute increase of 65% and 38% was observed creatine kinase, during continuous and intermittent running, respectively. Regarding hormonal responses when compared to baseline measurements, cortisol increased by 132% and 121% in the continuous and intermittent protocols, respectively. No correlation was found between biochemical, endocrinal and the neuromuscular variables.

CONCLUSIONS

The present findings showed that running until exhaustion performed at maximal lactate steady state, significantly impaired muscle strength and increased hormonal and muscle damage markers in two different protocols (i.e. continuous and intermittent) amongst trained runners.

Clinically symptomatic heterozygous carnitine palmitoyltransferase II (CPT II) deficiency

Two symptomatic patients with heterozygous carnitine palmitoyltransferase II (CPT II) deficiency are reported. Patient 1, a 21-year-old female professional tennis player, suffered from exercise-induced attacks of muscle pain, burning sensations and proximal weakness. Patient 2, a 30-year-old male amateur marathon runner developed muscle cramps and rhabdomyolysis upon extensive exercise and insolation-induced fever. In both patients, the common p.S113L mutation was found in heterozygote state. No second mutation could be found upon sequencing of all the exons of CPT2 gene including exon-intron boundaries. Biochemically, residual CPT activity in muscle homogenate upon inhibition by malonyl-CoA and Triton-X-100 was intermediate between controls and patients with mutations on both alleles. Although CPT II deficiency is an autosomal recessive disorder, the reported patients indicate that heterozygotes might also have typical attacks of myalgia, pareses or rhabdomyolysis.

Circulating cell-free DNA: an up-coming molecular marker in exercise physiology

The phenomenon of circulating cell-free DNA (cfDNA) concentrations is of importance for many biomedical disciplines including the field of exercise physiology. Increases of cfDNA due to exercise are described to be a potential hallmark for the overtraining syndrome and might be related to, or trigger adaptations of, immune function induced by strenuous exercise. At the same time, exercise provides a practicable model for studying the phenomenon of cfDNA that is described to be of pathophysiological relevance for different topics in clinical medicine like autoimmune diseases and cancer. In this review, we are summarizing the current knowledge of exercise-based acute and chronic alterations in cfDNA levels and their physiological significance. The effects of acute exercise on cfDNA concentrations have been investigated in resistance exercises and in continuous, stepwise and interval endurance exercises of different durations. cfDNA concentrations peaked immediately after acute exercise and showed a rapid return to baseline levels. Typical markers of skeletal muscle damage (creatine kinase, uric acid, C-reactive protein) show delayed kinetics compared with the cfDNA peak response. Exercise parameters such as intensity, duration or average energy expenditure do not explain the extent of increasing cfDNA concentrations after strenuous exercise. This could be due to complex processes inside the human organism during and after physical activity. Therefore, we hypothesize composite effects of different physiological stress parameters that come along with exercise to be responsible for increasing cfDNA concentrations. We suggest that due to acute stress, cfDNA levels increase rapidly by a spontaneous active or passive release mechanism that is not yet known. As a result of the rapid and parallel increase of cfDNA and lactate in an incremental treadmill test leading to exhaustion within 15-20 minutes, it is unlikely that cfDNA is released into the plasma by typical necrosis or apoptosis of cells in acute exercise settings. Recently, rapid DNA release mechanisms of activated immune-competent cells like NETosis (pathogen-induced cell death including the release of neutrophil extracellular traps [NETs]) have been discovered. cfDNA accumulations might comprise a similar kind of cell death including trap formation or an active release of cfDNA. Just like chronic diseases, chronic high-intensity resistance training protocols induced persistent increases of cfDNA levels. Chronic, strenuous exercise protocols, either long-duration endurance exercise or regular high-intensity workouts, induce chronic inflammation that might lead to a slow, constant release of DNA. This could be due to mechanisms of cell death like apoptosis or necrosis. Yet, it has neither been implicated nor proven sufficiently whether cfDNA can serve as a marker for overtraining. The relevance of cfDNA with regard to overtraining status, performance level, and the degree of physical exhaustion still remains unclear. Longitudinal studies are required that take into account standardized and controlled exercise, serial blood sampling, and large and homogeneous cohorts of different athletic achievement. Furthermore, it is important to establish standardized laboratory procedures for the measurement of genomic cfDNA concentrations by quantitative real-time polymerase chain reaction (PCR). We introduce a new hypothesis based on acute exercise and chronic exposure to stress, and rapid active and passive chronic release of cfDNA fragments into the circulation.

Metabolic markers in sports medicine

Physical exercise induces adaptations in metabolism considered beneficial for health. Athletic performance is linked to adaptations, training, and correct nutrition in individuals with genetic traits that can facilitate such adaptations. Intense and continuous exercise, training, and competitions, however, can induce changes in the serum concentrations of numerous laboratory parameters. When these modifications, especially elevated laboratory levels, result outside the reference range, further examinations are ordered or participation in training and competition is discontinued or sports practice loses its appeal. In order to correctly interpret commonly used laboratory data, laboratory professionals and sport physicians need to know the behavior of laboratory parameters during and after practice and competition. We reviewed the literature on liver, kidney, muscle, heart, energy, and bone parameters in athletes with a view to increase the knowledge about clinical chemistry applied to sport and to stimulate studies in this field. In liver metabolism, the interpretation of serum aminotransferases concentration in athletes should consider the release of aspartate aminotransferase (AST) from muscle and of alanine aminotransferase (ALT) mainly from the liver, when bilirubin can be elevated because of continuous hemolysis, which is typical of exercise. Muscle metabolism parameters such as creatine kinase (CK) are typically increased after exercise. This parameter can be used to interpret the physiological release of CK from muscle, its altered release due to rhabdomyolysis, or incomplete recovery due to overreaching or trauma. Cardiac markers are released during exercise, and especially endurance training. Increases in these markers should not simply be interpreted as a signal of cardiac damage or wall stress but rather as a sign of regulation of myocardial adaptation. Renal function can be followed in athletes by measuring serum creatinine concentration, but it should be interpreted considering the athlete's body-mass index (BMI) and phase of the competitive season; use of cystatin C could be a reliable alternative to creatinine. Exercise and training induce adaptations in glucose metabolism which improve glucose utilization in athletes and are beneficial for reducing insulin insensitivity in nonathletes. Glucose metabolism differs slightly for different sports disciplines, as revealed in laboratory levels. Sport activities induce a blood lipid profile superior to that of sedentary subjects. There are few reports for a definitive conclusion, however. The differences between athletes and sedentary subjects are mainly due to high-density lipoprotein cholesterol (HDLC) concentrations in physically active individuals, although some differences among sport disciplines exist. The effect of sports on serum and urinary markers for bone metabolism is not univocal; further studies are needed to establish the real and effective influence of sport on bone turnover and especially to establish its beneficial effect.

Diurnal variations of plasma homocysteine, total antioxidant status, and biological markers of muscle injury during repeated sprint: effect on performance and muscle fatigue--a pilot study

The aim of this study was (i) to evaluate whether homocysteine (Hcy), total antioxidant status (TAS), and biological markers of muscle injury would be affected by time of day (TOD) in football players and (ii) to establish a relationship between diurnal variation of these biomarkers and the daytime rhythm of power and muscle fatigue during repeated sprint ability (RSA) exercise. In counterbalanced order, 12 football (soccer) players performed an RSA test (5 x[6 s of maximal cycling sprint + 24 s of rest]) on two different occasions: 07:00-08:30 h and 17:00-18:30 h. Fasting blood samples were collected from a forearm vein before and 3-5 min after each RSA test. Core temperature, rating of perceived exertion, and performances (i.e., Sprint 1, Sprint 2, and power decrease) during the RSA test were significantly higher at 17:00 than 07:00 h (p < .001, p < .05, and p < .05, respectively). The results also showed significant diurnal variation of resting Hcy levels and all biological markers of muscle injury with acrophases (peak times) observed at 17:00 h. These fluctuations persisted after the RSA test. However, biomarkers of antioxidant status' resting levels (i.e., total antioxidant status, uric acid, and total bilirubin) were higher in the morning. This TOD effect was suppressed after exercise for TAS and uric acid. In conclusion, the present study confirms diurnal variation of Hcy, selected biological markers of cellular damage, and antioxidant status in young football players. Also, the higher performances and muscle fatigue showed in the evening during RSA exercise might be due to higher levels of biological markers of muscle injury and lower antioxidant status at this TOD.