Postexercise increase in nitric oxide in football players with muscle cramps

Nitrosative Stress in Astronaut Skeletal Muscle in Spaceflight

Long-duration mission (LDM) astronauts from the International Space Station (ISS) (>180 ISS days) revealed a close-to-normal sarcolemmal nitric oxide synthase type-1 (NOS1) immunoexpression in myofibers together with biochemical and quantitative qPCR changes in deep calf soleus muscle. Nitro-DIGE analyses identified functional proteins (structural, metabolic, mitochondrial) that were over-nitrosylated post- vs. preflight. In a short-duration mission (SDM) astronaut (9 ISS days), s-nitrosylation of a nodal protein of the glycolytic flux, specific proteins in tricarboxylic acid (TCA) cycle, respiratory chain, and over-nitrosylation of creatine kinase M-types as signs of impaired ATP production and muscle contraction proteins were seen. S-nitrosylation of serotransferrin (TF) or carbonic anhydrase 3 (CA3b and 3c) represented signs of acute response microgravity muscle maladaptation. LDM nitrosoprofiles reflected recovery of mitochondrial activity, contraction proteins, and iron transporter TF as signs of muscle adaptation to microgravity. Nitrosated antioxidant proteins, alcohol dehydrogenase 5/S-nitrosoglutathione reductase (ADH5/GSNOR), and selenoprotein thioredoxin reductase 1 (TXNRD1) levels indicated signs of altered redox homeostasis and reduced protection from nitrosative stress in spaceflight. This work presents a novel spaceflight-generated dataset on s-nitrosylated muscle protein signatures from astronauts that helps both to better understand the structural and molecular networks associated to muscular nitrosative stress and to design countermeasures to dysfunction and impaired performance control in human spaceflight missions.

Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports

The majority of reviews on sports nutrition issues focus on macronutrients, often omitting or paying less attention to substances such as sodium. Through the literature, it is clear that there are no reviews that focus entirely on the effects of sodium and in particular on endurance sports. Sodium intake, both at high and low doses, has been found to be associated with health and performance issues in athletes. Besides, there have been theories that an electrolyte imbalance, specifically sodium, contributes to the development of muscle cramps (EAMC) and hyponatremia (EAH). For this reason, it is necessary to create this systematic review, in order to report extensively on the role of sodium consumption in the population and more specifically in endurance and ultra-endurance athletes, the relationship between the amount consumed and the occurrence of pathological disorders, the usefulness of simultaneous hydration and whether a disturbance of this substance leads to EAH and EAMC. As a method of data collection, this study focused on exploring literature from 2000–2021. The search was conducted through the research engines PubMed and Scopus. In order to reduce the health and performance effects in endurance athletes, simultaneous emphasis should be placed on both sodium and fluid intake.

The Effect of Hot Water Extract of Tilapia on Exercise Capacity in Mice

Tilapia (Oreochromis mossambicus) has become one of the main aquatic products of Taiwan. The aim of this study was to evaluate the efficacy of a hot water extract of tilapia (HWET) in relieving fatigue and enhancing exercise performance in mice in a swimming endurance test. Male ICR mice were randomly divided into four groups (n = 10 per group) and treated with either a vehicle (control group) or different doses of HWET, which were designated as HWET-L (800 mg/kg/day), HWET-M (1600 mg/kg/day), and HWET-H (4000 mg/kg/day). The results of the swimming endurance test showed that HWET treatment significantly improved exercise-induced fatigue as the swimming time of the mice increased (p < 0.05). One hour after the test, blood samples were collected from each mouse and serum biochemical parameters were measured. The serum levels of lactate, creatine kinase (CK), and blood urea nitrogen (BUN) were lower in mice treated with HWET compared to the control group. Moreover, HWET treatment increased serum glucose levels and glycogen content in the liver. Enhanced glutathione (GSH) content in the liver and muscle was also found in the HWET-M and HWET-H groups. Western blot results showed that the expression of tumor necrosis factor-α (TNF-α) in the liver tissue was downregulated by HWET treatment. Taken together, our results demonstrate that HWET supplementation could enhance exercise performance and alleviate fatigue via biochemical profile improvements. This suggests that HWET has the potential for future development into functional foods or nutritional supplements to relieve fatigue.

Effects of melatonin ingestion on physical performance and biochemical responses following exhaustive running exercise in soccer players

Antioxidant supplementation has become a common practice among athletes to boost sport achievement. Likewise, melatonin (MEL) has been ingested as an ergogenic aid to improve physical performance. To date, no study has checked whether the multiple beneficial effects of MEL have an outcome during a maximum running exercise until exhaustion. Therefore, the present study aimed to evaluate the effect of MEL ingestion on physical performance and biochemical responses (i.e., oxidative stress) during exhaustive exercise. In a double blind randomized study, thirteen professional soccer players [age: 17.5 ± 0.8 years, body mass: 70.3 ± 3.9 kg, body height: 1.80 ± 0.08 m; maximal aerobic speed (MAS): 16.85 ± 0.63 km/h; mean ± standard deviation], members of a first league squad, performed a running exercise until exhaustion at 100% of MAS, after either MEL or placebo ingestion. Physical performance was assessed, and blood samples were obtained at rest and following the exercise. Compared to placebo, MEL intake prevented the increase in oxidative stress markers (i.e., malondialdehyde), alleviated the alteration of antioxidant status (i.e., glutathione peroxidase, uric acid and total bilirubin) and decreased post-exercise biomarkers of muscle damage (i.e., creatine kinase and lactate dehydrogenase) (p < 0.05). However, physical performance was not affected by MEL ingestion (p > 0.05). In conclusion, acute MEL intake before a maximal running exercise protected athletes from oxidative stress and cellular damage but without an effect on physical performance.

Exercise-Associated Muscle Cramps in the Tennis Player

PURPOSE OF REVIEW

Better define the proposed etiologies, risk factors, and treatment plans for exercise-associated muscle cramps in the tennis player.

RECENT FINDINGS

While no one theory has been able to fully explain the etiology behind exercise-associated muscle cramping, further classification of acute localized cramping and systemic or recurrent cramping may help guide future treatment and prevention strategies. Neuromuscular fatigue more than electrolyte deficit or dehydration is believed to play a large role in development of exercise-associated muscle cramps. Despite inconclusive evidence at this time, electrolyte deficit may play more of a role in the development of recurrent or systemic muscle cramping in the tennis athlete. More research is needed to better define its conclusive etiology.

Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining

Muscle cramp is a temporary but intense and painful involuntary contraction of skeletal muscle that can occur in many different situations. The causes of, and cures for, the cramps that occur during or soon after exercise remain uncertain, although there is evidence that some cases may be associated with disturbances of water and salt balance, while others appear to involve sustained abnormal spinal reflex activity secondary to fatigue of the affected muscles. Evidence in favour of a role for dyshydration comes largely from medical records obtained in large industrial settings, although it is supported by one large-scale intervention trial and by field trials involving small numbers of athletes. Cramp is notoriously unpredictable, making laboratory studies difficult, but experimental models involving electrical stimulation or intense voluntary contractions of small muscles held in a shortened position can induce cramp in many, although not all, individuals. These studies show that dehydration has no effect on the stimulation frequency required to initiate cramping and confirm a role for spinal pathways, but their relevance to the spontaneous cramps that occur during exercise is questionable. There is a long history of folk remedies for treatment or prevention of cramps; some may reduce the likelihood of some forms of cramping and reduce its intensity and duration, but none are consistently effective. It seems likely that there are different types of cramp that are initiated by different mechanisms; if this is the case, the search for a single strategy for prevention or treatment is unlikely to succeed.

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.

The athlete with muscular cramps: clinical approach

Muscle cramps are involuntary, painful, spasmodic contractions of the skeletal muscle. Although cramps are a common clinical complaint, their etiology and management have not been well established. Exercise-associated muscle cramps occur during or immediately following exercise, and they are associated with muscular fatigue and shortened muscle contraction. The main challenges for treating physicians are to identify whether the complaint represents a true muscle cramp as well as to rule out the presence of an underlying serious clinical condition. Muscle cramps may be a symptom of any of several conditions, including radiculopathies, Parkinson's disease, hypothyroidism, diabetes mellitus, vascular problems, electrolyte disorders, and metabolic myopathies. Cramps also may occur as a side effect of certain drugs (eg, lipid-lowering agents, antihypertensives, beta-agonists, insulin, oral contraceptives, alcohol). Most athletes who experience exercise-associated muscle cramps are healthy individuals without systemic illness. Therapy should focus on preventing premature fatigue by means of appropriate nutrition and adequate training.

Hydration status in college football players during consecutive days of twice-a-day preseason practices

BACKGROUND

Football players lose 3.5 to 5 kg of body weight during preseason practices because of heavy sweating. This fluid may be difficult to replace when practices occur 2 times per day on consecutive days.

HYPOTHESIS

Football players are hypohydrated during twice-a-day preseason training in a hot, humid environment.

STUDY DESIGN

Descriptive laboratory study.

METHODS

In 10 college football players, body weight was measured, and blood and urine samples were obtained before and after practices on days 2 through 8 of preseason training. Baseline samples were obtained when subjects were euhydrated. Blood samples were used to calculate plasma volume changes. Urine samples were analyzed for specific gravity, sodium, and potassium. Sweat rate was calculated. Core temperature was monitored during half- and full-padded practices.

RESULTS

Mean wet bulb temperatures were 23.3 degrees C during morning practices and 23.7 degrees C during afternoon practices. Plasma volume was below baseline on day 2 and expanded by day 6. Urine specific gravity was higher than baseline for 12 of 20 measurements over the 8 days. It was 1.0175 +/- 0.006 at baseline but subsequently ranged from 1.0214 +/- 0.007 to 1.0321 +/- 0.004. Mean daily urine sodium dropped from baseline to day 2 (194 +/- 43 vs 43 +/- 38 mmol x L-1), remaining lower on days 3, 4, and 6 (40 +/- 39, 39 +/- 39, and 68 +/- 40 mmol x L-1, respectively). Urine potassium was lower on days 6 and 8 compared with baseline and day 3. Body weight was below baseline before and after both daily practices. Core temperature was higher in full pads; sweat rate and body weight loss were not different between half and full pads.

CONCLUSION

Body weight, plasma volume, urine specific gravity, and urine sodium indicate that football players become dehydrated by day 2 of preseason training. Urine sodium increased to near baseline by day 8; urine specific gravity was elevated.

CLINICAL RELEVANCE

Football players struggle to maintain euhydration during preseason twice-a-day sessions.

Energy demands during a judo match and recovery

OBJECTIVE

To assess energy demand during a judo match and the kinetics of recovery by measuring the metabolites of the oxypurine cascade, lipolytic activity, and glycolytic pathway.

METHODS

Venous blood samples were taken from 16 national judoists (mean (SEM) age 18.4 (1.6) years), before (T(1)) and three minutes (T(2)), one hour (T(3)), and 24 hours (T(4)) after a match. A seven day diet record was used to evaluate nutrient intake.

RESULTS

Nutrient analysis indicated that these athletes followed a low carbohydrate diet. Plasma lactate concentration had increased to 12.3 (1.8) mmol/l at the end of the match. An increase in the levels of extracellular markers of muscle adenine nucleotide catabolism, urea, and creatinine was observed at T(2), while uric acid levels remained unchanged. High concentrations of urea persisted for 24 hours during the recovery period. Ammonia, hypoxanthine, xanthine, and creatinine returned to control levels within the 24 hour recovery period. Uric acid concentrations rose from T(3) and had not returned to baseline 24 hours after the match. The levels of triglycerides, glycerol, and free fatty acids had increased significantly (p<0.05) after the match (T(2)) but returned to baseline values within 24 hours. Concentrations of high density lipoprotein cholesterol and total cholesterol were significantly increased after the match.

CONCLUSIONS

These results show that a judo match induces both protein and lipid metabolism. Carbohydrate availability, training adaptation, and metabolic stress may explain the requirement for these types of metabolism.

Muscular cramps: proposals for a new classification

Muscle cramps are involuntary, painful, sudden contractions of the skeletal muscles. They are present in normal subjects under certain conditions (during a strong voluntary contraction, sleep, sports, pregnancy) and in several pathologies such as myopathies, neuropathies, motoneuron diseases, metabolic disorders, hydroelectrolyte imbalances or endocrine pathologies. There has been considerable uncertainty in the literature regarding the classification and nomenclature of muscle cramps, both because the term "cramp" is used to indicate a variety of clinical features of muscles, leading to its use as an imprecise "umbrella" term that includes stiffness, contractures and local pain, and because the spectrum of the diseases in which it appears is wide. The purpose of the present study is to propose a simple classification to provide a framework to better recognize the full spectrum of phenomenology of muscle cramps.

Performance, biochemical, and endocrine changes during a competitive football game

PURPOSE

This study represents the first time that anaerobic power performance was examined during an actual intercollegiate American football game. In addition, biochemical and endocrine responses also were examined to assess the physiological stress imposed by this competitive contest.

METHODS

Twenty-one members of a NCAA Division III football team were divided into two groups. Group one (ST) were starters (N = 11). The second group (RS) consisted of red-shirt players (N = 10). Blood samples were obtained 24 h (Pre1) and 2.5 h (Pre2) before the game and within 15 min of game conclusion (IP). Anaerobic power measures were recorded approximately 10 min before kickoff (pre) and following the first (Q1), second (Q2), third (Q3), and fourth (Q4) quarters.

RESULTS

Peak force (PF) and power (PP) in both squat and countermovement jumps decreased (P < 0.05) from pre to Q2 in both ST and RS; however, all variables returned to baseline levels by Q4. When averaged across trials, PF and PP in both jumps were greater (P < 0.05) in ST than RS. No significant changes in testosterone concentrations with respect to time or between groups were seen. Cortisol concentrations were significantly higher for ST at IP than RS. No significant changes in creatine kinase, alanine aminotransferase, urea, or uric acid were observed in either group from Pre2 to IP. In addition, no between group differences were seen in these variables. Myoglobin and aspartate aminotransferase significantly increased from Pre2 to IP in ST, and a significant difference in myoglobin concentrations was seen between the groups at IP.

CONCLUSIONS

Performance, biochemical, and endocrine changes in these NCAA Division III football players reflected the stress and muscle damage that occurs as a result of a competitive American football game.

Nitric oxide in skeletal muscle: inhibition of nitric oxide synthase inhibits walking speed in rats

Nitric oxide (NO*) is a multifunctional messenger molecule generated by a family of enzymes called the nitric oxide synthases (NOSs). Although NOSs have been identified in skeletal muscle, specifically brain NOS (bNOS) and endothelial NOS (eNOS), their role has not been well clarified. The goals of this investigation were to (1) characterize the immunoreactivity, Ca(2+) dependence, and activity of NOS in human and rat skeletal muscle and (2) using a rat model, investigate the effect of chronic blockade of NOS on skeletal muscle structure and function. Our results showed that both human and rodent skeletal muscle had NOS activity. This NOS activity was similar to that of the endothelial and brain NOS isoforms in that it was calcium-dependent. However, Western blot analysis consistently showed that a polyclonal antibody raised against a peptide sequence of human inducible NOS (iNOS) reacted with a protein with a molecular weight (95 kDa) that was different from that of other NOS isoforms. RT-PCR analysis identified the mRNA expression of not only eNOS and bNOS but also iNOS in human and rat muscle. Inhibition of nitric oxide synthase in rats with N(omega)-nitro-L-arginine methyl ester (L-NAME) resulted in a progressive, severe reduction in walking speed (30-fold reduction in walking velocity at day 22, P < 0.001), muscle fiber cross-sectional area (40% reduction at day 22, P < 0.001), and muscle mass (40% reduction in dry weight at day 22, P < 0.01). Rats fed the same regimen of the enantiomer of L-NAME (d-NAME) had normal motor function, muscle fiber morphology, and muscle mass. Taken together, these results imply that there may be a novel nitric oxide synthase in muscle and that NO. generated from muscle may be important in muscle function.