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Abstract
Magnesium is an essential element that regulates membrane stability and neuromuscular, cardiovascular, immune, and hormonal functions and is a critical cofactor in many metabolic reactions. The Dietary Reference Intake for magnesium for adults is 310 to 420 mg/day. However, the intake of magnesium in humans is often suboptimal. Magnesium deficiency may lead to changes in gastrointestinal, cardiovascular, and neuromuscular function. Physical exercise may deplete magnesium, which, together with a marginal dietary magnesium intake, may impair energy metabolism efficiency and the capacity for physical work. Magnesium assessment has been a challenge because of the absence of an accurate and convenient assessment method. Recently, magnesium has been touted as an agent for increasing athletic performance. This article reviews the various studies that have been conducted to investigate the relationship of magnesium and exercise.
... Magnesium (Mg) is the fourth-most abundant mineral and has important roles in the formation of bones and teeth, energy production, and over 300 enzymatic reactions in the human body (1,2). Mg is also involved in membrane stability, cardiac excitability, nerve conduction, and muscular contraction (2,3). ...
... Magnesium (Mg) is the fourth-most abundant mineral and has important roles in the formation of bones and teeth, energy production, and over 300 enzymatic reactions in the human body (1,2). Mg is also involved in membrane stability, cardiac excitability, nerve conduction, and muscular contraction (2,3). Thus, Mg is one of the most essential minerals in humans. ...
... If Mg intake is suboptimal, the body seeks to maintain serum concentrations by increasing Mg absorption in the intestine and Mg reabsorption in the kidneys, and by releasing stored Mg, such as that stored in bone (7). Therefore, Mg deficiency is relatively rare (1,2). However, if there is a large imbalance between gastrointestinal absorption and renal excretion, Mg deficiency may still occur (2). ...
Little is known about the optimal daily magnesium (Mg) intake for individuals with high levels of physical activity. The aim of this study was to clarify the optimal dietary Mg intake for people with high levels of physical activity in a scoping review. In this review, we searched MEDLINE and Japan Medical Abstracts Society for studies published up to May 31, 2020. We conducted two searches, one for studies using gold standard measurement methods such as the balance method and factorial calculation (Search 1), and the other for studies using estimation from daily food intake (Search 2). We also performed a meta-analysis of studies that compared the Mg intake among physically active people with the Mg intake among controls. After the primary and secondary screening, 31 studies were included in the final review. All of the included studies examined professional or recreational athletes. We found no studies that examined the optimal intake of Mg using gold standard measurement methods. The Mg intake among physically active individuals was below the recommended dietary allowance in most studies. In five studies that conducted meta-analyses, physically active individuals had significantly higher intakes of Mg than controls, although these levels were still below the recommended dietary allowance. The present review revealed that evidence regarding the optimal daily magnesium intake is currently scarce, and further studies are needed.
... Son yıllarda içme suyu ve obezite ile ilişkinin farklı boyutlarını inceleyen pek çok çalışma yapılmaktadır. Ancak bu çalışmalarda genellikle içme suyu ile alınan minerallerin günlük önerilen mineral alım düzeyine herhangi bir katkısı olup olmadığı, suyun sertliği ile hastalıklar arasındaki ilişki (özellikle kardiyovasküler hastalıklar) incelenmiştir (9)(10)(11). ...
... Suyun bileşimi hakkında yapılan çalışmalar ise suyun sertliğinin/yumuşaklığının kardiyovasküler hastalıklar (KVH) başta olmak üzere, kan basıncı, metabolik sendrom gibi sağlık üzerine etkilerini incelemiştir. Bu nedenle üzerinde durulan mineraller suyun sertliğini büyük ölçüde belirleyen kalsiyum ve magnezyumdur (9)(10)(11). ...
Su ile alınan minerallerin iyon şeklinde görünmeleri ve sindirim yolunda hemen emilmelerinden dolayı içme suyu, mineral alımında önemli bir kaynak olmaktadır. Ancak içme suyundaki eser element seviyelerinin, çocukların vücut kompozisyonları ile nasıl bir ilişki içinde olduğu henüz kapsamlı bir araştırmaya rastlanmamıştır. Bunun üzerine bu çalışmada, içme suyundaki klinik olarak önemli eser element seviyeleri ile Batman'daki çocukların vücut kompozisyonları arasındaki ilişkiyi değerlendirme amaçlandı. Araştırmanın örneklemi, Batman Bölge Devlet Hastanesi Diyet Polikliniği'ne başvuran beden kütle indeksi (BKİ) ile persentil eğrilerine göre fazla kilolu, obez ve normal kilolu olarak 20 kişilik gruplara ayrılan 13-18 yaş aralığındaki (ortalama yaş 15.9±1.68) kız çocuklarından oluşturuldu. İndüktif eşleşmiş plazma spektrometresi kullanarak, belediyenin ve şahısların kuyularındaki sulardan alınan örneklerde lityum (Li), nikel, kurşun (Pb), silisyum, kalay, stronsiyum (Sr), bor, alüminyum (Al), baryum ve rubidyum seviyeleri ölçüldü. Vücut kompozisyonu ölçümleri biyoelektrik empedans cihazı (Tanita BC 418) ile gerçekleştirildi. İçme suyundaki lityum seviyeleri, bütün çocuklarda BKİ, yağ kütlesi ve yağ yüzdesi ile önemli ölçüde pozitif korelasyon göstermiştir. Benzer şekilde, içme suyundaki kurşun seviyeleri de çocuklarda BKİ, yağ kütlesi ve yağ yüzdesi ile önemli ölçüde pozitif korelasyon göstermiştir. Son olarak, içme suyundaki Al ve Sr seviyeleri, çocuklardaki vücut ağırlığı, BKİ, yağ yüzdesi ve vücut kompozisyonunun dahil olduğu birçok değişken ile önemli ölçüde pozitif korelasyon göstermiştir. Elde edilen bu bulgulara göre; suyun içeriğinde bulunan Li, Pb, Al ve Sr seviyelerinin 13-18 yaşlarındaki çocukların vücut kompozisyonları ile ilişkili olduğu önerilebilir. Anahtar kelimeler: Çocukluk çağı bazitesin, içme suyu, eser elementler, beden kütle indeksi. Drinking water is a significant source in mineral intake due to the fact that waterborne minerals are present in ionic form and are instantly absorbed by the gastrointestinal tract. However, up until now, no comprehensive research has been encountered about how levels of trace elements in drinking water are related with body compositions of the children. Thereupon, in this study, it was aimed to assess the relationship between clinically important trace element levels in public drinking water and body composition of the children in Batman. The universe of the study consisted of female children, at the age range of 13-18 (mean age 15.9±1.68), who were divided into overweight, obese and normal weight groups of 20 participants, according to body mass index (BMI) and percentile curves, and who applied to Batman Regional State Hospital Diet Policlinic. The levels of lithium (Li), nickel, lead (Pb), silicon, stannum, strontium (Sr), boron, aluminium (Al), barium and rubidium were measured in water samples obtained from municipality and individual wells by employing inductively coupled plasma spectrometry. Body composition measurements were performed by means of bioelectrical impedance analysis (Tanita BC 418). Li levels in drinking water showed significantly positive correlations with BMI, fat mass and fat percentage in all children. Similarly, Pb levels in drinking water showed significantly positive correlations with BMI, fat mass and fat percentage in children. Finally, Al and Sr levels in drinking water showed significantly positive correlations with body weight, BMI, fat percentage and several variables of body composition in children. According to the findings obtained, it may be suggested that there is a relationship between Li, Pb, Al and Sr contents in drinking water and body composition of children aged 13-18.
... Generally, magnesium is mostly stored in the bone, tissues, organs, and blood, while mainly being excreted through the urine (Volpe, 2013). Moreover, magnesium is mainly involved in the processes of protein synthesis, cellular energy production and storage, reproduction, DNA and RNA synthesis, and stabilizing mitochondrial membranes (Bohl and Volpe, 2002;Burgess et al., 2015;Chubanov et al., 2005;Newhouse and Finstad, 2000). In addition, magnesium plays a critical role in maintaining normal nerve and muscle function, cardiac excitability (normal heart rhythm), neuromuscular conduction, muscular contraction, vasomotor tone, blood pressure, bone integrity, and glucose and insulin metabolism (Barbagallo et al., 2003;Bohl and Volpe, 2002;Burgess et al., 2015;Chubanov et al., 2005;Rodriguez-Moran, 2000, 2002;He et al., 2006;Lopez-Ridaura et al., 2004;McCarty, 2005;Murakami et al., 2005;Newhouse and Finstad, 2000;Paolisso and Barbagallo, 1997;Soltani et al., 2005). ...
... Moreover, magnesium is mainly involved in the processes of protein synthesis, cellular energy production and storage, reproduction, DNA and RNA synthesis, and stabilizing mitochondrial membranes (Bohl and Volpe, 2002;Burgess et al., 2015;Chubanov et al., 2005;Newhouse and Finstad, 2000). In addition, magnesium plays a critical role in maintaining normal nerve and muscle function, cardiac excitability (normal heart rhythm), neuromuscular conduction, muscular contraction, vasomotor tone, blood pressure, bone integrity, and glucose and insulin metabolism (Barbagallo et al., 2003;Bohl and Volpe, 2002;Burgess et al., 2015;Chubanov et al., 2005;Rodriguez-Moran, 2000, 2002;He et al., 2006;Lopez-Ridaura et al., 2004;McCarty, 2005;Murakami et al., 2005;Newhouse and Finstad, 2000;Paolisso and Barbagallo, 1997;Soltani et al., 2005). ...
Magnesium is integral to many physiological processes, while variations in its levels, even within the normal range, can have critical implications for health. To explore the broad clinical effects of varying serum magnesium levels, we performed a two-sample Mendelian randomization and phenome-wide association study (MR-PheWAS) in the UK Biobank cohort. In total, MR-PheWAS analysis implicated a causal role of serum magnesium levels in five disease groups and six disease outcomes. Additionally, our study indicated the gender-specific effects of nine disease groups/outcomes in MR estimated effects. The protein-protein interaction network demonstrated an interaction between the serum magnesium-associated gene DCDC1 and the cataract- associated gene PAX6. The present study verified several previously reported disease outcomes and identified novel potential disease outcomes for serum magnesium levels. The DCDC1 gene and the PAX6 gene may be the new targets for promoting the treatments of cataracts using magnesium intervention.
... The level of elevated electrolytes could not measure correctly since certain amounts of electrolytes were lost by sweat and perspiration during the longterm exercises or this decrease might result from the elevation in the muscle sodium-potassium pumping action accompanied by rapid loss of intracellular potassium (Bohl et al., 2002;Shirreffs et al., 2004;Rayssiguier et al., 2011). ...
... If the loss of magnesium through sweat exceeded its concentration in the blood, this might cause cramps in the muscles (Bohl et al., 2002;Kodama et al., 2009;Rayssiguier et al., 2011). ...
... However, Mg can be profusely lost through transpiration [10], making it difficult to establish correct assessments regarding Mg distribution in the different body compartments during supplementation protocols. In addition to this instrumental limitation, other factors that can complicate the interpretation of results include a variety of experimental designs, different exercise intensities and duration, timing for obtaining blood samples, environmental conditions and stress during performance [2,3,5,6,[11][12][13]. Correct Mg assessment in the body requires specific overloading protocols that are tedious to perform during competition [3,13]. ...
... A muscle biopsy together with an overloading protocol could be a more realistic approach to analyze Mg redistribution between body compartments, but these invasive protocols cannot be performed during such a demanding race as "Vuelta a España". Therefore, serum Mg determination is not sufficient to paint a full picture of redistribution of Mg from one storage area (release) to an active site (muscle or adipose tissue), as previously documented [1,11,23,[26][27][28]. Also, we have to consider the losses through sweat and urine, which are estimated at 10-20% [3]. ...
Magnesium is a cofactor of different enzymatic reactions involved in anabolic and catabolic processes that affect muscular performance during exercise. In addition, it has been suggested that magnesium could participate in maintaining muscle integrity during demanding effort. The main purpose of this study was to analyze the effects of magnesium supplementation in preventing muscle damage in professional cyclists taking part in a 21-day cycling stage race. Eighteen male professional cyclists (n = 18) from two teams were recruited to participate in the research. They were divided into 2 groups: the control group (n = 9) and the magnesium-supplemented group (n = 9). The supplementation consisted of an intake of 400 mg/day of magnesium during the 3 weeks of competition. Blood samples were collected according to World Anti-Doping Agency rules at three specific moments during competition: immediately before the race; mid competition; and before the last stage. Levels of serum and erythrocyte magnesium, lactate dehydrogenase, creatinine kinase, aspartate transaminase, alanine transaminase, myoglobin, aldolase, total proteins, cortisol and creatinine were determined. Serum and erythrocyte magnesium levels decreased during the race. Circulating tissue markers increased at the end of the race in both groups. However, myoglobin increase was mitigated in the supplemented group compared with the controls. We conclude that magnesium supplementation seems to exert a protective effect on muscle damage.
... [8] Body magnesium is consumed during physical activities which results in negative effects on energy metabolism and physical activity and some athletes use magnesium supplements for their optimal performance. [9,10] In line with ...
... Heavy exercises discharge magnesium through changing the blood magnesium level or through increased urination and sweat. [9] It seems that the amount of magnesium consumed in this study was substituted with the probable discharged on during exercising. ...
Background and Objective: Magnesium is a critical cation in human body that can block some receptors and channels associated with nociception. Aerobic exercise (AE) increases pain threshold in athletes. In this study, we investigated the effects of chronic administration of magnesium oxide nanoparticles (MgONPs) and MgO on nociception in the presence and absence of AE-induced analgesia. Materials and Methods: Adult male Wistar rats were divided into six groups: Two controls (saline and exercise groups), four intervention groups: MgONPs and bulk MgO groups (receiving intraperitoneal 1 mg/kg for 5 days/week and 6 weeks) with and without exercise. The exercise groups were trained 30 min using treadmill after the injections. At the end of the 6th week, analgesia time was evaluated by hot plate test. Results: AE significantly reduced pain response compared with the control group (P < 0.01). In addition, both MgO and MgONPs significantly reduced pain response than the control group (P < 0.001). There were no significant differences between analgesic effect of exercise alone and MgO or MgONPs with exercise. Conclusion: The analgesic effects of AE and MgO supplements are probably induced by common mechanisms in the central nervous system.
... These results are consistent with previous reviews based on qualitative studies using a food frequency questionnaire [19,41]. Mg is involved in muscle relaxation and contraction [42], and its supplementation reportedly improves physical function [43]. K is reportedly involved in neurotransmission and muscle contraction, and it has been recently reported that VB6 intake is associated with agility and mobility and that its contribution is derived from fruits [44]. ...
Japan is experiencing a super-ageing society faster than anywhere else in the world. Consequently, extending healthy life expectancy is an urgent social issue. To realize a diet that can support the extension of healthy life expectancy, we studied the quantitative relationships among physical activities (number of steps and activity calculated using an accelerometer), physical functions (muscle strength, movement function, agility, static balance, dynamic balance, and walking function), and dietary intake among 469 older adults living in the Tokyo metropolitan area (65–75 years old; 303 women and 166 men) from 23 February 2017 to 31 March 2018. Physical activities and functions were instrumentally measured, and the dietary survey adopted the photographic record method. There was a significant positive association (p < 0.05) between physical activities (steps, medium-intensity activity, and high-intensity activity) and physical functions (movement function, static balance, and walking function), but no association with muscle strength. These three physical functions were significantly positively correlated with intake of vegetables, seeds, fruits, and milk; with magnesium, potassium, and vitamin B6; and with the dietary fibre/carbohydrate composition ratio (p < 0.05). Future intervention trials must verify if balancing diet and nutrition can improve physical activities in older adults through increased physical functions.
... Physically active individuals are at increased risk of Mg deficiency due to increased needs and loss 50,51 . Physical activity regulates Mg distribution and utilization 52 , translocating Mg from plazma to adipocites and skeletal muscle. ...
Magnesium is a cofactor in more than 300 enzymes, it plays a vital role in energy metabolism, homeostasis of electrolites, and bone metabolism, and regulates a number of fundamental functions such as muscle contraction, neuromuscular conduction, glycemic control, and blood pressure. Magnesium deficiency has been associated with a wide range of diseases, from cardiovascular diseases, hypertension, diabetes, to anxiety and other mental disorders, migraine and osteoporosis, and especially worrying is subclinical form which is estimated to affect up to 30% of the population. Recommended dietary intake of magnesium is 300 mg and 350 mg per day for adult males and females, respectively. While highly abundant in a variety of foods, especially green leafy vegetables, nuts and seeds, water is the main contributor to magnesium daily intake. Water has been the focus of a number of public health interventions aiming to improve magnesium status of populations, especially in Israel and Australia. Supplements are becoming a more important contributor to the total magnesium intake, especially among physically active individuals. Public awareness of the health benefits gained from physical activity is improving, and more individuals decide to engage in (recreational) physical activity. Even though physical activity increases the risk of magnesium deficiency, misuse of supplements due to lack of knowledge and misinformation shared on social networks can have a detrimental effect on individual’s health and physical performance.
... Our study indicated that on average, blood iron concentration after iron supplementation during weight loss increased compared with that in the placebo. Similar research has found that blood iron concentration increased after weight loss compared with before, as the ions released from the intracellular fluid increased the concentration of extracellular fluid [25,26]. Previous studies have shown these results and as well as significant results associated with 7% weight loss. ...
... Mg is found in vegetables and seeds; K is found in vegetables and fruits; VB6 is found in meat, fish, and seeds; and fibre is found in vegetables and fruits. Mg is involved in muscle relaxation and contraction [33], and its supplementation reportedly improves physical function [34]. K is reportedly involved in neurotransmission and muscle contraction, and it has been recently reported that VB6 intake is associated with agility and mobility [35]. ...
Japan is experiencing a super-aging society faster than is anywhere else worldwide. Consequently, extending healthy life expectancy is an urgent social issue. To understand diet that supports the extension of healthy life expectancy, we studied the relationships among quality of life (QOL: SF-36 questionnaire), physical activity (number of steps and activity calculated using an accelerometer), physical function (muscle strength, movement function, agility, static balance, dynamic balance, and walking function) and dietary intake among 469 older adults living in the Tokyo metropolitan area (65–75 years old, men/women = 166/303) from February 23, 2017, to March 31, 2018. There was a significant positive association between physical QOL and steps, moderate-intensity activity, and high-intensity activity (p < 0.05), and a significant positive association (p < 0.05) between physical activity and movement, static balance, and walking functions, but no association with muscle strength. These three body functions were significantly positively correlated with intake of vegetables, seeds, fruits, and milk, and with magnesium, potassium, vitamin B6, and the dietary fibre/carbohydrate ratio and composition ratios (p < 0.05). Balancing food and nutrition may improve QOL in older adults through increased physical function and physical activity. Future verification of interventions is needed.
... Magnesium functions primarily as a structural or enzymatic cofactor, helping to maintain protein structure and/or enzyme function. The presence of this mineral in the diet is crucial for normal biological functions because magnesium is required for adenosine triphosphate (ATP) metabolism, overall cellular energy production and storage, reproductive functions, stabilization of mitochondrial membranes, and the synthesis of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and proteins [8,34,[36][37][38][39]. Magnesium is implicated in protein, nucleotide, and mitochondrial structure [34]. ...
The Mediterranean Diet (MedDiet) is a nutritional pattern native to many cultures within the Mediterranean Basin. The diet is composed of fruits, vegetables, fish, eggs, fermented dairy, grains, poultry, and minimal consumption of red meats such as lamb and beef. The diet encourages the consumption of extra virgin olive oil and moderate red wine for those who consume alcohol. The diet does not incorporate processed foods and sugary beverages. The MedDiet is rich in many micronutrients and has a healthful fatty acid profile (primarily mono- and polyunsaturated fats, with low amounts of saturated fats). The diet is rich in foods with high magnesium content, such as leafy green vegetables, nuts, seeds, and some lesser magnesium-rich foods (e.g., fish). The MedDiet is associated with reduced incidence of several diseases such as cardiovascular disease, cerebrovascular disease, neurodegenerative disease, metabolic syndrome, and type 2 diabetes mellitus. Magnesium intake has been shown to play a prominent role in the prevention and management of many of these diseases, with some of the disease-preventing capacity of the MedDiet likely caused by its high magnesium content. Those making nutritional recommendations in line with the concepts of MedDiet should particularly encourage the consumption of foods high in magnesium.
... Women who develop gestational diabetes or anemia during pregnancy are at risk for poor postpartum fitness [47]; these are modifiable risk factors that should be addressed with regular moderate-intensity physical activity and adequate iron supplementation during pregnancy in order to optimize athletic performance during the postpartum period. Besides low iron, magnesium deficiency may also reduce physical performance and negatively affect exercise capacity, as it plays a central role in the control of neuronal activity, cardiac excitability, neuromuscular transmission, muscular contraction, vasomotor tone, and blood pressure [48]. A loss of intracellular magnesium can lead to muscle weakness, neuromuscular dysfunction, and cramping or spasms. ...
Purpose of Review
The exponential growth of women participating in competitive sports throughout the years was made possible through several initiatives by the International Olympic Committee and the passage and implementation of Title IX as a federal law in the United States. However, this positive trend towards gender equity in sports has not transpired for women in medicine, especially in fields that care for elite athletes. This current review will discuss specific areas that can be tailored to help female athletes prevent injuries and optimize their athletic performance. We will also highlight how increased female team physician representation in sports may help optimize care for female athletes.
Recent Findings
Female athletes are considered high risk for certain conditions such as ACL tears, patellofemoral pain syndrome, bone stress injuries, sport-related concussions, and sexual violence in sport. Addressing factors specific to female athletes has been found to be valuable in preventing injuries. Strength and conditioning can optimize athletic performance but remains underutilized among female athletes. Although diversity in healthcare workforce has been found to be beneficial for multiple reasons, women remain underrepresented in sports medicine. Increasing female team physician representation may positively impact care for female athletes.
Summary
Team physicians must understand the physiologic, biomechanical, and anatomic factors that are unique to female athletes in order to tailor injury prevention programs and optimize their athletic performance. Advocating for gender equity in sports medicine to advance representation of women in the field will increase workforce diversity and promote excellence in sports medicine care.
... Chromium is known for its structure of glucose tolerance factor (GTF) and tasks of insulin hormone regulation (11). Magnesium is an element involved in energy metabolism, protein synthesis and muscle contraction-relaxation (12). Many studies report that exercise has different levels of effect on body electrolyte balance, electrolyte deficiency causes symptoms such as muscle cramps and adversely affect sports performance (13,14). ...
This study aims to investigate the acute effect of sparring training applied to elite boxers on serum
levels of electrolytes such as Sodium, Potassium, Magnesium, Chlorine, Chromium, Calcium.Methods: The
research group consists of 22 elite male boxers of the national team, who took part in the study voluntarily,
with the age 18.36 ± 6.18, body weight 65.23 ± 11.75 kg, height 174.18 ± 8.67 cm. Sparring training model
including free lower-body strikes to the liver was applied to the participants. For the detection of serum
electrolyte levels, blood samples were taken from antecubital region of each athlete before and after the
training. Serum samples obtained were centrifuged at 3000 rpm for 10 minutes in laboratory and analyzed at
COBAS C 501 analyzer through photometric method. SPSS 22.0 statistical program was used for the analysis
of the data obtained. The normality distribution of the data was tested by Shapiro-Wilk test, descriptive
statistics and Paired t-test, one of the parametric tests, were used for statistical analysis of normally
distributed data. Results: Comparing the electrolyte values of elite boxers before and after training, it was
found that there is a statistically significant difference in magnesium, chlorine and chromium values (p
<0.05) and there is no significant difference in sodium, potassium and calcium values (p> 0.05).
Conclusion:As a result of the research, it was concluded that the effect of boxing training specifically based
on strikes to lower body on the parameters examined in this study is similar to the literature findings, hence
sparring training does not have a significant effect on the parameters tested.
... Magnesium serves a variety of important biological functions [20]. It is a cofactor by over 300 enzymes in biological processes [7,21], include, but are not limited to, protein synthesis, energy generation and storage, reproduction, DNA replication, RNA transcription, and mitochondrial membrane stabilization [22,23]. And it is important for the transmission of nerve impulses and muscle contraction [24]. ...
... Exercise is known to redistribute magnesium in the body (16). In general, short-term, high-intensity exercise results in a transient ~5-15% increase, while prolonged endurance exercise reduces circulating concentrations of magnesium [reviewed in (16,31)]. In the current study, the serum magnesium response to military training varied based on sex. ...
Maintaining magnesium status may be important for military recruits, a population that experiences high rates of stress fracture during initial military training (IMT). The objectives of this secondary analysis were to 1) compare dietary magnesium intake and serum magnesium in female and male recruits pre- and post- IMT, 2) determine whether serum magnesium was related to parameters of bone health pre-IMT, and 3) whether calcium and vitamin D supplementation (Ca/vitamin D) during IMT modified serum magnesium. Females (n=62) and males (n=51) consumed 2,000 mg calcium and 1,000 IU vitamin D/d or placebo during IMT (12 weeks). Dietary magnesium intakes were estimated using FFQ, serum magnesium was assessed, and pQCT was performed on the tibia. Dietary magnesium intakes for females and males pre-IMT were below the estimated average requirement and did not change with training. Serum magnesium increased during IMT in females (0.06±0.08 mmol/L) compared to males (−0.02±0.10 mmol/L; P<0.001) and in those consuming Ca/vitamin D (0.05±0.09 mmol/L) compared to placebo (0.001±0.11 mmol/L; P=0.015). In females, serum magnesium was associated with total bone mineral content (BMC, β=0.367, P=0.004) and robustness (β=0.393, P=0.006) at the distal 4% site, stress strain index (SSIp, β=0.334, P=0.009) and robustness (β=0.420, P=0.004) at the 14% diaphyseal site, and BMC (β=0.309, P=0.009) and SSIp (β=0.314, P=0.006) at the 66% diaphyseal site pre-IMT. No significant relationships between serum magnesium and bone measures were observed in males. Findings suggest that serum magnesium may be modulated by Ca/vitamin D intake and may impact tibial bone health during training in female military recruits.
... [29] On the other hand, the evaluation of serum magnesium may not represent the better index of body storage, because extracellular magnesium represents only 1% of the total amount of body and seems to be strictly regulated. In this regard, the assessment of urinary magnesium concentrations might better quantify the variation of this ion in the body [31], although we had not the possibility to test it. Regarding physical performance, we found a trend towards improvement in lower limb strength expressed as maximum flexion strength in both groups. ...
Background and aims
COPD is a common chronic condition in older age that impacts on daily activities and quality of life. Previous studies suggest that magnesium deficit in COPD patients affects bronco-obstruction, inflammation, and physical performance. We investigated whether oral magnesium supplementation in stable-phase COPD patients improves lung function, physical performance, and quality of life.
Methods
We conducted a double-blind randomized-controlled clinical study with 49 participants divided into two groups: one given 300 mg/day of magnesium citrate ( n = 25) and the other one sachet/day of a placebo ( n = 24). The following parameters were assessed at baseline and after 3 and 6 months: lung function (spirometry), physical performance (handgrip strength, lower limb strength, six-minute walk test), inflammation (e.g., C-reactive protein, CRP), disease-related symptoms, and quality of life (St George’s Respiratory Questionnaire, EuroQoL-5D, the Modified British Medical Research Council Questionnaire).
Results
Linear mixed models revealed significantly lower CRP values in the intervention group than in the placebo group at the 6 month follow-up ( β = − 3.2, 95% CI − 6.0, − 0.4, p = 0.03). Moreover, the maximum work for flexion tended to increase in both groups between the 3 and the 6 month assessments, especially in the placebo group. No significant differences within and between groups over the study period were observed for the other parameters tested.
Conclusions
Although the established minimum sample size was not reached, our results suggests that oral magnesium supplementation may have a potential anti-inflammatory role. On the other hand, it does not seem to substantially influence lung function, physical performance, and quality of life in COPD patients.
Trial registration
The study is registered in clinicaltrial.gov (Trial Registration: NCT02680769, 13 June 2016, retrospectively registered).
... Magnesium, a vital mineral regulates membrane stability and neuromuscular, cardiovascular, immunological, and hormonal functions and is a critical cofactor in many metabolic reactions [82] including energy metabolism, [83] cell growth, [84] glycolysis [85] and protein synthesis. [86] Muscle performance is positively associated with serum magnesium levels in male athletes. ...
... Most well-controlled research indicates that magnesium supplementation (500 mg/d) does not affect exercise performance in athletes unless there is a deficiency 370,371 . ...
... Magnesium (Mg) is another vital mineral for the body's function, specifically regarding energy metabolism, transmembrane transport, muscle relaxation and contraction [62]. Mg tends to be of increased demand in elite athletes [63]. ...
Basketball can be described as a moderate- to long-duration exercise including repeated bouts of high-intensity activity interspersed with periods of low to moderate active recovery or passive rest. Basketball games are characterized by repeated explosive activities, such as sprints, jumps, shuffles, and rapid changes in direction. In top-level modern basketball, players are frequently required to play consecutive games with limited time to recover. To ensure adequate recovery from basketball-specific activities, it is necessary to know the type of fatigue induced and if possible its underlying mechanisms. Recovery strategies are commonly utilized in basketball despite limited scientific evidence to support their effectiveness in facilitating optimal recovery. It is particularly important to optimize recovery because players spend a much greater proportion of their time recovering than they do in training. Therefore, the aim of this chapter is to distribute useful information for practical application, based on the scientific evidence and applied knowledge in basketball.
... 1 It is an essential element that regulates membrane stability and has neuromuscular, cardiovascular, immune and hormonal functions. 2 Mg or magnesium ion (Mg 2+ ) deficiency leads to a wide variety of metabolic abnormalities and clinical consequences. 3 Mg deficiency has also been identified as a risk factor for cardiovascular diseases such as coronary artery disease. ...
Background:Mechanisms for QT interval prolongation and cardiac arrhythmogenesis in hypomagnesemia are poorly understood. This study investigated the potential molecular mechanism for QT prolongation caused by magnesium (Mg) deficiency in rats by using the patch clamp technique and molecular biology.
Methods and Results:Male Wistar rats were fed an Mg-free diet or a normal diet for up to 12 weeks. There was QT prolongation in the ECG of Mg-deficient rats, and cardiomyocytes from these rats showed prolongation of action potential duration. Electrophysiological studies showed that inward-rectifying K⁺current (IK1) and transient outward K⁺current (Ito) were decreased in Mg-deficient cardiomyocytes, and these findings were consistent with the downregulation of mRNA, as well as protein levels of Kir2.1 and Kv4.2. In Mg-deficient cardiomyocytes, transcription factors, GATA4 and NFAT, were upregulated, whereas CREB was downregulated. In contrast to Mg deficiency, cellular Mg²⁺overload in cultured cardiomyocytes resulted in the upregulation of Kir2.1 and Kv4.2, which was accompanied by the downregulation of GATA4 and NFATc4, and the upregulation of CREB. Activation of NFAT and inhibition of CREB reduced Kv4.2-Ito, whereas Kir2.1-IK1was reduced by CREB inhibition but not by NFTA activation.
Conclusions:Intracellular Mg deficiency downregulates IK1and Itoin cardiomyocytes, and this is mediated by the transcription factors, NFAT and CREB. These results provide a novel mechanism for the long-term QT interval prolongation in hypomagnesemia.
... A aferição do magnésio sérico, plasmático ou eritrocitário é o indicador do estado nutricional mais utilizado. A excreção urinária de magnésio é usada para avaliar o estado nutricional em magnésio, com um teste de sobrecarga, cujo método é considerado o mais confiável na detecção da deficiência de magnésio 22 . ...
RESUMO
Este trabalho é uma revisão de literatura que teve como objetivo descrever a Importância do Magnésio na Doença Cardiovascular. Foram realizadas compilações bibliográficas sobre artigos científicos originais e de revisão em revistas indexadas. O trabalho descreveu que o íon magnésio está envolvido em mais de 300 reações enzimáticas do organismo, possuindo propriedades anti-inflamatórias, antioxidantes e moduladoras do crescimento celular com a função de reduzir o estresse oxidativo. A deficiência do magnésio está associada à síndrome metabólica, hipertensão, insuficiência cardíaca congestiva, diabetes melittus e arritmias. Concluiu-se que o magnésio por ter função de relaxar a musculatura lisa dos vasos cardíacos, dilata as coronárias, melhora a contratilidade do miocárdio, reduz os riscos de espasmos coronarianos e inibe a agregação plaquetária, aumentando a relação prostaciclina/ tromboxano. Como possui um efeito dilatador, diminui a pressão arterial. Tem função estabilizante do ritmo cardíaco. Desempenhando assim um importante papel nas doenças cardiovasculares.
... 1 3 (Heffernan et al. 2019). Further than this, it has been proposed that individuals who consistently take part in exercise may require a 10-20% higher intake of magnesium, in contrast to their sedentary counterparts (Nielsen and Lukaski 2006), and as such, athletes are susceptible to frequent short-term marginal disruptions in magnesium homeostasis, in part due to an increased loss of magnesium in sweat (Shirreffs and Maughan 1997), increased excretion in the urine (Bohl and Volpe 2002), and low dietary magnesium intake (Heffernan et al. 2019). ...
Purpose
Magnesium supplementation modulates glucose metabolism and inflammation, which could influence exercise performance and recovery. This study investigated the effect of magnesium intake on physiological responses and performance during eccentric exercise and recovery.
Methods
Nine male recreational runners completed a counterbalanced, double-blind, placebo-controlled, cross-over study, registered at ClinicalTrial.gov. Participants consumed low magnesium diets and were supplemented with 500 mg/day of magnesium (SUP) or placebo (CON) for 7 days prior to a 10 km downhill (− 10%) running time trial (TT), separated by a 2-week washout period. At baseline and 24 h post-TT, maximal muscle force was measured. Interleukin-6 (IL-6), soluble interleukin-6 receptor (sIL-6R) and creatine kinase (CK) were measured at rest, 0 h, 1 h and 24 h post-TT. Muscle soreness was measured at the previous times plus 48 h and 72 h post. Glucose and lactate were measured during the TT.
Results
The main effect of condition was detected for IL-6 (SUP: 1.36 ± 0.66 vs CON: 2.06 ± 1.14 pg/ml) (P < 0.05, η² = 0.54), sIL-6R (SUP: 27,615 ± 8446 vs CON: 24,368 ± 7806 pg/ml) (P < 0.05, η² = 0.41) and muscle soreness (P < 0.01, η² = 0.67). Recovery of blood glucose and muscle soreness were enhanced in SUP post-TT. There were no differences in glucose and lactate during the TT, or post measures of CK and maximal muscle force.
Conclusion
Magnesium supplementation reduced the IL-6 response, enhanced recovery of blood glucose, and muscle soreness after strenuous exercise, but did not improve performance or functional measures of recovery.
... Magnesium is a significant component of every athlete's diet. Its deficit may lead to myasthenia, cramps, neuromuscular dysfunctions, immunosuppression [46], and it may also have an impact on physical-efficiency decrease [47]. Hence, balancing magnesium intake in keeping with the prescribed values is highly recommended for the examined group. ...
The aim of the study was to evaluate the energy expenditure and fulfillment of nutritional needs of female soccer players. Participants in this research were 41 professional soccer players from the three Polish female soccer league levels: Ekstraleague, I League and II League. The participants had their height and body mass measured. Total Energy Expenditure was measured by means of a SenseWear Pro3 Armband device. Data related to the food-intake energy values and the consumption of macro- and micronutrients were obtained through systematic recording of results, which was conducted over a three-day-long period at the start of the competitive season. The average age of the participants was 21 ± 5 years, the average height was 167.5 ± 5 cm, and the average body mass was 62.53 ± 9.8 kg. The average energy expenditure of the participants was 2811 ± 493 kcal/day, and their average energy intake was 1476 ± 434 kcal/day. The average consumption of carbohydrates, fats, and proteins was 199 ± 20.6, 47.3 ± 20.7, and 72.3 ± 24.2 g/day, respectively. There was a prevalence of inadequate intake of potassium, calcium, magnesium, iodine, vitamins D, E and B1, and folate in the diet of the examined group. The remaining micronutrients were consumed in the prescribed amounts by at least 50% of the examined group. The participants demonstrated low energy intakes, and consequently, low consumption of macronutrients and a large number of micronutrients.
... Most well-controlled research indicates that magnesium supplementation (500 mg/d) does not affect exercise performance in athletes unless there is a deficiency [730,731]. ...
Background:
Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words 'sport nutrition'. Consequently, staying current with the relevant literature is often difficult.
Methods:
This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches.
Conclusions:
This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.
... The nutritional value of cucumber fruit per 100 g edible portion is water (95%), carbohydrate (3%), protein (1 %), total fat (0.5%) and dietary fibre (1%) (USDA, National Nutrient Data Base, 2014). Cucumber fruit is a veritable source of vitamins such as vitamin A, C, K, E and minerals including potassium, manganese, phosphorus, calcium and zinc which are essential for protein, nucleic acid synthesis and also contributes to maintain blood pressure, structural development of bones [Bohl and Volpe 2010]. Furthermore, cucumber folk medicine includes treatment of diabetes, hypertension, diar-rhoea, gonorrhoea and also used to detoxify, as an anti-inflammatory, analgesic, antioxidant and serum lipids regulator [Abu-Reidah et al. 2012]. ...
An experiment was conducted to evaluate the effect of different concentration and combination of potassium [1.0 g/l (K1), 2.5 g/l (K2) and 5.0 g/l (K3)] and gibberellic acid [0.005 g/l (G1), 0.01 g/l (G2) and 0.015 g/l (G3)] foliar application on growth characteristics, quality and yield of F1hybrid cucumber (cv. KUK-9).The results showed that the highest amounts for growth, biochemical attributes, fruit maturity, quality belonged to K2 (2.5 g/l) plus G2 (0.01 g/l) combination treatment. Plant height as well as chlorophyll content attained their greatest quantities under G2K2 treatment. Dry matter, TSS % and antioxidant activity showed significant differences compared with control, G1K1 and G2K2 treatment showed the greatest sum of data. Fruit mineral content were also significantly affected by different treatments. Higher fruit potassium was recorded with G3K3 treatment.
Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature regarding the effects of energy drink (ED) or energy shot (ES) consumption on acute exercise performance, metabolism, and cognition, along with synergistic exercise-related performance outcomes and training adaptations. The following 13 points constitute the consensus of the Society and have been approved by the Research Committee of the Society: Energy drinks (ED) commonly contain caffeine, taurine, ginseng, guarana, carnitine, choline, B vitamins (vitamins B1, B2, B3, B5, B6, B9, and B12), vitamin C, vitamin A (beta carotene), vitamin D, electrolytes (sodium, potassium, magnesium, and calcium), sugars (nutritive and non-nutritive sweeteners), tyrosine, and L-theanine, with prevalence for each ingredient ranging from 1.3 to 100%. Energy drinks can enhance acute aerobic exercise performance, largely influenced by the amount of caffeine (> 200 mg or >3 mg∙kg bodyweight [BW⁻¹]) in the beverage. Although ED and ES contain several nutrients that are purported to affect mental and/or physical performance, the primary ergogenic nutrients in most ED and ES based on scientific evidence appear to be caffeine and/or the carbohydrate provision. The ergogenic value of caffeine on mental and physical performance has been well-established, but the potential additive benefits of other nutrients contained in ED and ES remains to be determined. Consuming ED and ES 10-60 minutes before exercise can improve mental focus, alertness, anaerobic performance, and/or endurance performance with doses >3 mg∙kg BW⁻¹. Consuming ED and ES containing at least 3 mg∙kg BW⁻¹ caffeine is most likely to benefit maximal lower-body power production. Consuming ED and ES can improve endurance, repeat sprint performance, and sport-specific tasks in the context of team sports. Many ED and ES contain numerous ingredients that either have not been studied or evaluated in combination with other nutrients contained in the ED or ES. For this reason, these products need to be studied to demonstrate efficacy of single- and multi-nutrient formulations for physical and cognitive performance as well as for safety. Limited evidence is available to suggest that consumption of low-calorie ED and ES during training and/or weight loss trials may provide ergogenic benefit and/or promote additional weight control, potentially through enhanced training capacity. However, ingestion of higher calorie ED may promote weight gain if the energy intake from consumption of ED is not carefully considered as part of the total daily energy intake. Individuals should consider the impact of regular coingestion of high glycemic index carbohydrates from ED and ES on metabolic health, blood glucose, and insulin levels. Adolescents (aged 12 through 18) should exercise caution and seek parental guidance when considering the consumption of ED and ES, particularly in excessive amounts (e.g. > 400 mg), as limited evidence is available regarding the safety of these products among this population. Additionally, ED and ES are not recommended for children (aged 2-12), those who are pregnant, trying to become pregnant, or breastfeeding and those who are sensitive to caffeine. Diabetics and individuals with preexisting cardiovascular, metabolic, hepatorenal, and/or neurologic disease who are taking medications that may be affected by high glycemic load foods, caffeine, and/or other stimulants should exercise caution and consult with their physician prior to consuming ED. The decision to consume ED or ES should be based upon the beverage’s content of carbohydrate, caffeine, and other nutrients and a thorough understanding of the potential side effects. Indiscriminate use of ED or ES, especially if multiple servings per day are consumed or when consumed with other caffeinated beverages and/or foods, may lead to adverse effects. The purpose of this review is to provide an update to the position stand of the International Society of Sports Nutrition (ISSN) integrating current literature on ED and ES in exercise, sport, and medicine. The effects of consuming these beverages on acute exercise performance, metabolism, markers of clinical health, and cognition are addressed, as well as more chronic effects when evaluating ED/ES use with exercise-related training adaptions.
Magnesium and vitamin D are two micronutrients that contribute directly to the metabolism of macronutrients, maintenance of muscle function, and various metabolic processes (i.e., protein synthesis and bone metabolism). Dietary recommendations are established based on age and gender differences; however, energy expenditure is not accounted for in determining these values. It is believed that athletes may require greater nutrient quantities than less active populations because of their increased energy expenditure. Nutrient intake values have yet to be determined for athletes, leading to inadequate energy intake, deficiencies, and insufficiencies; thus, supplementation may be an effective way of achieving nutrient adequacy in athletes. The purpose of this narrative review was to present research pertaining to magnesium supplementation and vitamin D supplementation on exercise performance. A systematic keyword search for articles from PubMed was conducted from June to August 2020. The search terms included various words related to the topic. Inclusion criteria required articles to be available in English; to be a clinical trial, randomized controlled trial, or longitudinal study; and to involve magnesium supplementation, vitamin D supplementation, or supplementation of both micronutrients. In addition, the research conducted on magnesium or vitamin D were required to focus on athletes or those who exercised regularly. However, because of the paucity of published data regarding the combined effects of magnesium and vitamin D supplementation on exercise performance, those studies that could provide some information in nonathletic populations were included. The search did not limit the years in which studies were published because of the scarcity of articles related to the topic. After reviewing the articles for originality and applicability, 13 studies were included in our narrative review. Some researchers have reported that magnesium supplementation may provide ergogenic benefits via contributions to muscle function and recovery. In addition, some researchers have reported that vitamin D supplementation may positively affect physical endurance and muscle recovery in athletes. However, more research is required to provide more definitive conclusions. The interactions between magnesium and vitamin D during metabolism may potentiate the functions of each micronutrient, making the combined effects of magnesium and vitamin D greater than the effects of either one alone. However, research is required to elucidate their combined effects on exercise performance.
Background and aim
Physical activity is defined as any bodily movement produced by skeletal muscles which causes energy consumption; moderate and constant physical activity is known to be beneficial and to slow the muscle loss process associated with aging. The aim of the present study was to test, in an in vitro exercise model, the biological effects of a new formulation composed of magnesium and potassium combined with vitamin D and curcumin created to support muscle activity and to prevent hypercontraction damage.
Experimental procedure
C2C12 cells were treated with vitamin D, buffered magnesium bisglycinate, curcumin, and potassium citrate. Cell viability, morpho-functional changes, calcium and magnesium movements, and the main kinases involved in glucose uptake were analyzed. The glycogen level and lactate were also evaluated.
Results and conclusion
Important results about a positive effect on mitochondrial activity, ATP production, oxygen consumption and in the physiological differentiation of C2C12 cells were obtained. Further experiments were performed under conditions that mimic the biological aspects of strenuous exercise. The combination of magnesium, vitamin D3, curcumin, and potassium citrate revealed beneficial effects on skeletal muscle cells under physiological conditions as well as while mimicking intense activity. In particular, in an in vitro model, they were able to control the hypercontraction, restoring ion fluxes, reducing inflammation signaling and supporting the main mechanism involved on aerobic activity. Our results have indicated for the first time that this new combination could be considered as a new nutraceutical formulation to improve physical performance and muscle recovery.
Bu çalışmada amaç, voleybolda en çok kullanıldığı bildirilen besinsel destekler (C ve D vitamini, demir, magnezyum, kafein, sporcu ve enerji içecekleri, dallı zincirli aminoasitler, HMB, glutamin, whey, kreatin, bikarbonat, karnitin) hakkında bilgi vermektedir. Derlemenin içeriği, daha önce çok sayıda araştırmanın toplanıp yorumlandığı besinsel desteklerle ilgili derleme ve ilgili yayınların referans listeleri ile voleybolcular üzerinde yapılmış araştırma makaleleri özetlenerek oluşturulmuştur. İçeriğin hazırlanmasında derlemelerden yararlanılmasının nedeni, çok sayıda ve farklı sonuçlara ulaşan araştırma makalelerinin seçiminde ortaya çıkabilecek bireysel yanlılığı ortadan kaldırmaktır. Voleybolcular üzerindeki çalışma sayısının azlığı nedeniyle voleybolda besinsel destek (takviye/suplement) kullanımına özgü bilgi yetersiz olsa da, suplementler ile ilgili verilen bilgilerin okuyana fikir verecek yeterlilikte olduğu düşünülmektedir. Sonuç olarak, suplementlerin yararlarını araştıran çalışmalar yapılmaya devam etmektedir ve kullanım yanıtları yöntemsel ve bireysel farklılık gösterebilmektedir. Diğer takviyelerin vücutta eksikliği olmadığı sürece sporcuda sağlık veya performansı iyileştirmesi olası değildir. Hatta antrenmana daptasyonunu köreltmesi nedeniyle performansa, yaralanma riskini artırması nedeniyle de sağlığa zararlı etkileri olabilir.
Magnesium is an essential nutrient that is involved in practically every major metabolic and biochemical process within the cell. The human body contains about 25 g of magnesium, with about 50%–60% in the bone and the remainder in soft tissue. Magnesium (Mg²⁺) is a divalent metal ion, the fourth most abundant cation in the body after calcium, potassium, and sodium. Food sources high in magnesium include green, leafy vegetables, unpolished grains, and nuts. Strong evidence suggests magnesium deficiency contributes to cardiovascular disease, the metabolic syndrome, type 2 diabetes, and osteoporosis. Magnesium status is difficult to measure but best defined by dietary intake coupled with serum magnesium concentrations and urinary magnesium excretion.
Aim: This study aims to determine the changes induced by a maximal exercise test until exhaustion on the serum and urinary concentrations of Magnesium (Mg), Phosphorous (P), Rubidium (Rb) and Strontium (Sr) in athletes (AG) and sedentary students (SG).
Methods: Fifty subjects participated in the study divided into two groups. In AG there were twenty-five male athletes and in SG there were twenty-five male sedentary students. Both groups performed an exercise test until exhaustion, starting at 8 or 10 km/h respectively, and increasing the speed at 1 km/h every 400 m. Serum and urine samples were obtained from all participants before and after the test.
Results: Regarding the basal status, AG showed lower values of Mg in serum (p < 0.05) and urine (p < 0.01), but higher concentrations of serum P (p < 0.05) in comparison to SG. Comparing the pre and post-test values, corrected or non-corrected for hemoconcentration in serum and for creatinine in urine, AG showed a decrease in serum Mg (p < 0.05), in serum P (p < 0.01) and in urinary Sr (p < 0.01) while an increase was observed in urinary P (p < 0.05) and in urinary Rb (p < 0.05).
Conclusions: It can be concluded that a treadmill test until exhaustion leads to changes in serum and urinary concentrations of minerals in both AG and SG males. This may reflect an adaptive response of the body to overcome the physical stress and, in some cases, to avoid loss of these elements.
Background: The present study aimed to determine changes occurring in the erythrocyte concentrations of Iron (Fe), Magnesium (Mg) and Phosphorous (P) of subjects with different levels of physical training living in the same area of Extremadura (Spain).
Methods: Thirty sedentary subjects (24.34 ± 3.02 years) without sports practice and a less active lifestyle, formed the control group (CG); 24 non-professional subjects (23.53 ± 1.85 years), who perform between 4 and 6 h/week of moderate sports practice without any performance objective and without following systematic training formed the group of subjects with a moderate level of training (MTG), and 22 professional cyclists (23.29 ± 2.73 years) at the beginning of their sports season, who performed more than 20 h/week of training, formed the high-level training group (HTG). Erythrocyte samples from all subjects were collected and frozen at − 80 °C until analysis. Erythrocyte analysis of Fe, Mg and P was performed by inductively coupled plasma mass spectrometry (ICP-MS). All results are expressed in μg/g Hb.
Results: The results showed that there were statistically significant lower concentrations of erythrocyte Fe, Mg and P in MTG and HTG than CG. All parameters (Fe, Mg and P concentrations in erythrocytes) correlated inversely with physical training.
Conclusions: Physical exercise produces a decrease in erythrocyte concentrations of Fe, Mg and P. This situation could cause alterations in the performance of athletes given the importance of these elements. For this reason, we recommend an erythrocyte control at the beginning, and during the training period, to avoid harmful deficits.
Gonzalez, AM, Pinzone, AG, Bram, J, Salisbury, JL, Lee, S, and Mangine, GT. Effect of multi-ingredient preworkout supplementation on repeated sprint performance in recreationally active men and women. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this investigation was to examine the effects of acute supplementation of a multi-ingredient preworkout supplement (MIPS), containing a proprietary blend of ancient peat and apple extracts, creatine monohydrate, taurine, ribose, and magnesium, on sprint cycling performance. Seventeen recreationally active men and women (23.2 ± 5.9 years; 172.9 ± 14.3 cm; 82.4 ± 14.5 kg) underwent 2 testing sessions administered in a randomized, counterbalanced, double-blind fashion. Subjects were provided either MIPS or placebo (PL) one hour before performing a sprint cycling protocol, which consisted of ten 5-second "all-out" sprints interspersed by 55 seconds of unloaded pedaling. Average power (PAVG), peak power (PPK), average velocity (VAVG), and distance covered were recorded for each sprint. Separate linear mixed models revealed decrements (p < 0.05) compared to the first sprint in PAVG (75-229 W) and PPK (79-209 W) throughout all consecutive sprints after the initial sprint during PL. Likewise, diminished (p ≤ 0.029) VAVG (3.37-6.36 m·s) and distance covered (7.77-9.00 m) were noted after the third and fifth sprints, respectively, during PL. By contrast, during MIPS, only VAVG decreased (2.34-5.87 m·s, p ≤ 0.002) on consecutive sprints after the first sprint, whereas PAVG and PPK were maintained. In addition, a significant decrease (p = 0.045) in distance covered was only observed on the ninth sprint during MIPS. These data suggest that recreational athletes who consumed the MIPS formulation, one hour before a repeated sprinting session on a cycle ergometer, better maintained performance compared with PL.
Magnesium plays a critical role in athlete health and performance. It is involved in numerous physiological mechanisms that support energy production, immune function, pain modulation, muscle function and bone health. Athletes may be susceptible to magnesium deficiency due to an increased utilization during exercise.
Objective: This study reports on the magnesium status of 192 Olympic and Paralympic athletes over the course of eight years.
Methods: Athletes on the British Athletics world class performance plan undertook blood testing for Red Cell Magnesium status. Their history of tendon pain, muscle and bone injury, ethnicity, sporting event and gender were also recorded. 510 samples from 192 athletes were included in the study.
Results: On at least one blood test during the study time, 22% of athletes were identified as clinically deficient (<1.19 mmol/L). The average red cell magnesium concentration was 1.34 nmol/L. Magnesium was significantly lower in female athletes and those with Black or Mixed-Race ethnicity and was higher in Throws athletes and Paralympians with Cerebral Palsy. Athletes with a history of achilles or patella tendon pain had significantly lower magnesium levels than average.
Conclusions: This study highlights the importance of investigating magnesium within this population to identify deficiency and support athlete health. Several areas for future work are identified to explore the relationship between magnesium and gender, ethnicity and tendon pain and muscle injury in athletes. Furthermore, new guidelines for magnesium status within athletics populations are proposed.
Clinically significant derangements in plasma electrolytes rarely occur outside of excessive exercise and/or extreme dietary habits. Overzealous hydration facilitates exercise-associated disorders of sodium concentration ([Na⁺]) as robust overhydration may induce hyponatremia, whereas severe fluid restriction may cause hypernatremia. Excessive exercise may facilitate plasma potassium ([K⁺]) disorders as prolonged endurance exercise may induce hypokalemia (profuse sweat losses), whereas unaccustomed high-intensity training may cause hyperkalemia (rhabdomyolysis). Restrictive diets coupled with extensive exercise may also lead to low (hypo) plasma levels of magnesium ([Mg⁺⁺]), calcium ([Ca⁺⁺]), or phosphate ([P⁻]), whereas fanatical supplementation may trigger high (hyper) blood levels of [Mg⁺⁺], [Ca⁺⁺], or [P⁻]. Thus, most exercise-associated electrolyte disorders in healthy individuals volitionally occur from improper training and/or unhealthy dietary habits and are largely preventable.
Background:
Exercise is an effective therapy for the management of diabetes because it helps regulate glucose and magnesium homeostasis. Nevertheless, the mechanisms by which exercise exerts effects on magnesium transport remain unclear. This study investigated the expression of genes encoding magnesium transporters (GMTs) after a three-month exercise program in diabetic patients.
Methods:
This study was conducted with a within-subject pre-post design. A total of 15 adult patients with type 2 diabetes mellitus (T2DM) were recruited and underwent a three-month indoor bicycle exercise program. The expression of five GMTs (CNNM2, TRPM6, TRPM7, SLC41A1, and SLC41A3) was determined in blood samples. Relevant anthropometric values and biochemical parameters were also determined.
Results:
Although the body weight and body mass index decreased after three months exercise, there were no significant differences. Fasting blood glucose, glycated hemoglobin (HbA1c), waist circumference, and magnesium levels decreased after the exercise program (p < 0.05). The expression of SLC41A1 and SLC41A3 were downregulated after exercise, but only CNNM2, TRPM6, and TRPM7 showed significantly decreased expression levels compared with those before the exercise program (p < 0.05).
Conclusion:
The three-month exercise program ameliorated blood glucose levels and downregulated the expression of magnesium-responsive genes in patients with T2DM.
Herein, the reproducibility and a double validation of on-body measurements provided by new wearable potentiometric ion sensors (WPISs) is presented. Sweat collected during sport practice was first analyzed using the developed device, the pH-meter and ion chromatography (IC) prior to on-body measurements (off-site validation). Subsequently, the accuracy of on-body measurements accomplished by the WPISs was evaluated by comparison with pH-meter readings and IC after collecting sweat (every 10-12.5 min) during sport practice. The developed device contains sensors for pH, Cl–, K+ and Na+ that are embedded in a flexible sampling cell for sweat analysis. The electrode array was fabricated employing MWCNTs (as ion-to-electron transducer) and stretchable materials that has been exhaustively characterized in terms of analytical performance, presenting Nernstian slopes within the expected physiological range of each ion analyte (Cl–: 10 – 100 mM, K+: 10 – 10 mM, Na+: 10 – 100 mM; and pH: 4.5 – 7.5), drift suitable for mid-term exercise practice (0.3±0.2 mV h-1), fast response time, adequate selectivity for sweat measurements and excellent reversibility. Besides that, the designed sampling cell avoids any sweat contamination and evaporation issues while supplying a passive sweat flow encompassing specifically the individual’s perspiration. The interpretation of ion concentration profiles may permit the identification of personal dynamic patterns in sweat composition while practicing sport.
Minerals are necessary for a number of metabolic processes in the body, and are also important in supporting growth and development. Minerals are also required in numerous reactions involved with exercise and physical activity, including energy, carbohydrate, fat and protein metabolism, oxygen transfer and delivery, and tissue repair.1.
Magnesium is the fourth most abundant mineral in the body and, after potassium, the second most plentiful intracellular cation. Intimately involved in multiple aspects of metabolism, magnesium is a required cofactor for over 300 regulatory enzymes.1 Besides its requirement for specific enzymes, magnesium is involved indirectly in all enzymatic processes, as adenosine triphosphate (ATP) must be complexed to magnesium to be metabolically available.2 Magnesium is required for carbohydrate, fat, and protein ultilization.3,4 During cell replication, magnesium is required to maintain an adequate supply of purine and pyrimidine nucleotides necessary for DNA and RNA production.4 Virtually all hormonal reactions are magnesium dependent.5 Through its association with sodium, potassium, and calcium, magnesium is closely involved in maintaining cellular electrolyte balance and adequate amounts of magnesium are needed to maintain normal levels of potassium.5 It is required to maintain voltages across cell membranes and for the transfer of electrical impulses in neurons and muscle cells 6.
Wearable potentiometric ion sensors (WPISs) have become an exciting analytical platform that combines chemical, material and electronic efforts to supply physiological information during certain human activities. The real possibility of wearing an analytical device with diverse configurations—sweatband, patches, garments—without disturbing the welfare of the carrier has enabled potentiometric ion sensors both as health quality and sport performance controllers. Recent studies show a large involvement of WPISs in the following of critical biomarkers (timely or continuously), such as sodium, potassium, calcium, magnesium, ammonium and chloride, which are present at relatively high concentrations in sweat (∼mM levels). Certainly, the non-invasive nature of WPISs and other significant features, e.g., simplicity and cost-effectiveness, have broadened new horizons in relation to applied analytical chemistry. This has been pointed out in the literature over the last decade with the predominance of two analytical outcomes: (i) the improvement of sport performance as a result of continuous detection of ions in sweat (health status of the individual) while decreasing physiological complications (injuries, muscle cramps, fatigue and dehydration) during practice; and (ii) advancements in clinical diagnostics and preventive medicine as a consequence of the monitoring of the health status of patients suffering from any kind of disorder. Beyond the undeniable importance of the integration of WPISs to satisfy current societal needs, the following crucial questions about misleading and missing analytical features need to be answered: To what extent is WPIS technology a reliable analytical tool for the quantification of ions? Is cross-validation the current bottleneck toward further progress? Which are the fundamental steps involving the ion-selective electrode side that would benefit WPIS outcomes? Why is sweat the main (and almost the only) biological fluid to be monitored by WPISs? What is the best sampling strategy to be incorporated into WPIS devices for on-body monitoring of sweat? Which precision limits should be considered to assure a reliable decision-making process? Accordingly, this review focuses on the progression of WPISs from an analytical perspective—merely our vision of the field—within the period between 2010 and 2018. An updated search using specific keywords (wearable, ion, potentiometry, sensor) provided 43 contributions, which are herein highlighted, with a sustainable acceleration over the last three years. Thus, this review describes the current state of WPIS technology, the construction of wearable all-solid-state potentiometric sensors, critical requirements of potentiometric sensors to be fulfilled in a wearable configuration and key features regarding the ideal implementation of WPISs as reliable messengers of physiological information in real scenarios.
ÖZ
Arı poleni, bal arıları ve iğnesiz arılar tarafından
çiçeklerden ve tohumlu bitkilerden toplanan floral
polenlerin nektar veya bal, enzimler, mum ve arı
sekresyonları ile yoğrulması sonucu oluşan bir arı
ürünüdür. Polen arılar tarafından daha sonra
tüketilmek üzere kovanda depolanır. Arı poleni, hem
besleyici özelliği hem de apiterapik fonksiyonları
sebebi ile yüzyıllardan beri insanlar tarafından da
tüketilmektedir. Yapısındaki polifenolik bileşikler,
flavonoidler, vitaminler, karbohidrat, protein, yağ
asitleri, çeşitli eser elementler, mineraller ve organik
bileşikler ile yararlı biyoaktif özellikler sergiler.
Bu çalışmada Gümüşhane (Merkez), Bayburt
(Demirözü) ve Erzurum (Arıbahçe)’dan temin edilen
arı polenlerinden hazırlanan homojen karışım ön
çözünürleştirme işlemine tabi tutuldu ve bu polen
örneklerinde Bakır, Çinko, Magnezyum ve Kalsiyum
düzeyleri Atomik Absorbsiyon Spektrometresi (AAS)
ile üç kez analiz edildi. Bakır miktarı 8,60±0,43
mg/kg, Çinko miktarı 35,30±2,13 mg/kg, Magnezyum
miktarı 1113,33±61,00 mg/kg ve Kalsiyum miktarı
1034,00±53,86 mg/kg olarak tespit edildi.
Bu çalışmada Kuzeydoğu Anadolu Bölgesinden
toplanan arı poleninin Bakır, Çinko, Magnezyum ve
Kalsiyum düzeylerinin günlük mineral ihtiyacına katkı
sağlayacak düzeyde olduğu belirlendi.
Anahtar Kelimeler: Polen, Bakır, Çinko, Kalsiyum, Magnezyum
ABSTRACT
Bee pollen is a bee product that resulting from a
gathering of floral pollen, collected from flowers and
seedy plants by honey bees and stingless bees, with
nectar or honey, enzymes, wax and bee secretions.
Pollen is stored by the bees in a hive to be consumed
later. Because of its nutritive properties and
apitherapic functions, bee pollen has been consumed
by humans for centuries. It exhibits beneficial
bioactive properties due to its polyphenolic
compounds, flavonoids, vitamins, carbohydrates,
proteins, fatty acids, various trace elements, minerals
and organic compounds.
In this study, the homogeneous mixtures of bee
pollens collected from Gümüşhane (Center), Bayburt
(Demirözü) and Erzurum (Arıbahçe) were subject to
pre-solubilization process and the levels of Copper,
Zinc, Magnesium, and Calcium of these pollen
samples were analyzed three times by Atomic
Absorption Spectrophotometer (AAS). The amount of
copper was 8.60±0.43 mg/kg, the amount of zinc was
35.30±2.13 mg/kg, the amount of magnesium was
1113.33±61.00 mg/kg and the amount of calcium was
1034.00±53.86 mg/kg.
In the present study, it was determined that
Copper, Zinc, Magnesium and Calcium levels of bee
pollen collected from Northeast Anatolian Region are
sufficient to contribute to daily mineral requirepment.
Keywords: Pollen, Copper, Zinc, Calcium, Magnesium.
Amaç: Arı sütü, genç işçi arıların salgı bezlerinden salgılanan, larvaların ve kraliçe bal arısının besin kaynağı olan bir arı ürünüdür. Kraliçe arının ve larvaların fizyolojik gelişimi için çok önemli olan arı sütü insanlar tarafından da besleyici özelliği ve sağlık üzerine pozitif etkileri olması sebebi ile tüketilmektedir. Arı sütü yapısında su, lipid, protein, karbonhidrat, amino asit, kısa peptidler, vitamin, fenolik bileşikler, eser element ve mineralleri barındırmaktadır. Arı sütü kompozisyonunun üretildiği bölgenin coğrafik yapısına, iklimine, bitki örtüsüne, depolama koşullarına ve arı ırkına bağlı olarak değiştiği öne sürülmektedir. Ayrıca arı sütü mineral içeriğinin coğrafik yapı ve iklimden bağımsız olarak sadece hasat dönemine bağlı olarak değiştiğini ileri süren çalışmalar da mevcuttur. Türkiye’de üretilen arı sütünün kimyasal içeriği ve biyolojik özellikleri ile ilgili çok fazla çalışma bulunmamaktadır. Bu çalışmada Türkiye’nin Bursa ili Mustafakemalpaşa ilçesinden temin edilen arı sütü örneklerinde bazı element düzeylerinin belirlenmesi amaçlandı.Gereç ve Yöntemler: Bakır (Cu), çinko (Zn), magnezyum (Mg) ve kalsiyum (Ca) element düzeyleri Atomik Absorbsiyon Spektrofotometresi (AAS) ile belirlendi (n=3). Her element için sonuçlar ortalama±standart sapma olarak sunuldu.Bulgular: Bursa arı sütünde Cu miktarı 3,25±0,05 mg/kg, Zn miktarı 23,87±1,33 mg/kg, Mg miktarı 794,33±38,44 mg/kg ve Ca miktarı 250,87±24,49 mg/kg olarak tespit edildi.Sonuç: Bursa arı sütünün element düzeyleri günlük mineral ihtiyacını karşılamaya katkı sağlayabilecek düzeydedir. Ancak mineral katkı oranının saptanabileceği ve tedavi amaçlı kullanılabilirliğiyle ilgili ileri in vivo çalışmalara ihtiyaç vardır.
In 54 cases of accidental death in cities with water hardness of 60 parts per million (ppm) or less, the mean myocardial magnesium concentration was 918 mug/g of dry tissue. This was 7% lower than the corresponding figure of 982 mug/g among 29 cases of accidental death in cities with water hardness of 300 ppm or more, and this difference was significant (P less than 0.01). There were no significant differences between the cities with soft and hard water in the mean myocardial concentrations of calcium, zinc, copper, chromium, lead or cadmium. These results are compatible with the belief that the relatively high death rates in some soft-water areas may be due to a suboptimal intake of magnesium, and that water-borne magnesium exerts a protective effect on the residents of hard-water areas.
Magnesium reabsorption and regulation within the kidney occur principally within the cortical thick ascending limb (cTAL) cells of the loop of Henle. Fluorometry with the dye, mag-fura-2, was used to characterize intracellular Mg2+ concentration ([Mg2+]i) in single cTAL cells. Primary cell cultures were prepared from porcine kidneys using a double antibody technique (goat anti-human Tamm-Horsfall and rabbit anti-goat IgG antibodies). Basal [Mg2+]i was 0.52 +/- 0.02 mM, which was approximately 2% of the total cellular Mg. Cells cultured (16 h) in high magnesium media (5 mM) maintained basal [Mg2+]i, 0.48 +/- 0.02, in the normal range. However, cells cultured in nominally magnesium-free media possessed [Mg2+]i, 0.27 +/- 0.01 mM, which was associated with a significant increase in net Mg transport, (control, 0.19 +/- 0.03 and low Mg, 0.35 +/- 0.01 nmol.mg-1 protein.min-1) as assessed by 28Mg uptake. Mg(2+)-depleted cells were subsequently placed in high Mg solution (5 mM) and the Mg2+ refill rate was assessed by fluorescence. [Mg2+]i returned to normal basal levels, 0.53 +/- 0.03 mM, with a refill rate of 257 +/- 37 nM/s. Mg2+ entry was not changed by 5.0 mM Ca2+ or 2 mM Sr2+, Cd2+, Co2+, nor Ba2+ but was inhibited by Mn2+ approximately La3+ approximately Gd3+ approximately Zn2+ approximately Be2+ at 2 mM. Intracellular Ca2+ and 45Ca uptake was not altered by Mg depletion or Mg2+ refill, indicating that the entry is relatively specific to Mg2+. Mg2+ uptake was inhibited by nifedipine (117 +/- 20 nM/s), verapamil (165 +/- 34 nM/s), and diltiazem (194 +/- 19 nM/s) but enhanced by the dihydropyridine analogue, Bay K 8644 (366 +/- 71 nM/s). These antagonists and agonists were reversible with removal and [Mg2+]i subsequently returned to normal basal levels. Mg2+ entry rate was concentration and voltage dependent and maximally stimulated after 4 h in magnesium-free media. Cellular magnesium depletion results in increases in a Mg2+ refill rate which is dependent, in part, on de novo protein synthesis. These data provide evidence for novel Mg2+ entry pathways in cTAL cells which are specific for Mg2+ and highly regulated. These entry pathways are likely involved with renal Mg2+ homeostasis.
The purpose of this study was to measure magnesium absorption over the wide range of intakes to which the intestine may be exposed from food and/or magnesium-containing medications. Net magnesium absorption was measured in normal subjects after they ingested a standard meal supplemented with 0, 10, 20, 40, and 80 mEq of magnesium acetate. Although absorption increased with each increment in intake, fractional magnesium absorption fell progressively (from 65% at the lowest to 11% at the highest intake) so that absorption as a function of intake was curvilinear. This absorption-intake relationship was almost perfectly represented by an equation containing a hyperbolic function plus a linear function. Our results are statistically compatible with a magnesium absorption process that simultaneously uses a mechanism that reaches an absorptive maximum, plus a mechanism that endlessly absorbs a defined fraction (7%) of ingested magnesium. Compared to previous studies of calcium absorption, much less magnesium that calcium was absorbed at intakes above 8 mEq/meal, apparently due to greater restriction of intestinal permeability to magnesium. We also found that magnesium from a high magnesium-containing food source, almonds, was just as bioavailable as from soluble magnesium acetate. In contrast, magnesium absorption from commercially available enteric-coated magnesium chloride was much less than from magnesium acetate, suggesting that enteric coating can impair magnesium bioavailability.
Erythrocyte, plasma and urinary magnesium were observed in a group of 8 well-trained swimmers and in a group of 10 untrained subjects before, 2 minutes after and 30 minutes after a swimming test. After effort, plasma Mg (pMg) decreased significantly in both groups. Erythrocyte and urinary Mg variations were not significant in this study. PMg decrease after effort was more important in the swimmers group than in the untrained group (12% versus 6% after 2 minutes; 21% versus 4% after 30 minutes). The observed fall in plasma Mg concentration after exercise cannot be explained by a shift into erythrocytes during exercise, since the Mg content of these blood cells did not suffer significant alterations. The possible causes of the observed phenomena are discussed.
Magnesium, zinc, and copper status of 270 US Navy Sea, Air, and Land (SEAL) trainees was determined from dietary intakes and biochemical profiles. Although mean intakes exceeded the Recommended Dietary Allowances or the Estimated Safe and Adequate Intake range, intakes of 34%, 44%, and 37% of the trainees were below the recommendations for Mg, Zn, and Cu, respectively. Mean plasma concentrations were 0.85 +/- 0.004 mmol/L, 13.4 +/- 0.2 mumol/L, and 16.5 +/- 0.2 mumol/L for Mg, Zn, and Cu respectively. Mean 24-h urinary excretions were 5.7 +/- 0.2 mmol, 11.1 +/- 0.3 mumol, and 0.05 +/- 0.003 mumol, for Mg, Zn, and Cu, respectively. The data provided by the present study should be useful for comparing other physically active male populations.
Antacids used to decrease phosphorus absorption in patients with renal failure may be toxic. To find more efficient or less toxic binders, a three-part study was conducted. First, theoretical calculations showed that phosphorus binding occurs in the following order of avidity: Al3+ greater than H+ greater than Ca2+ greater than Mg2+. In the presence of acid (as in the stomach), aluminum can therefore bind phosphorus better than calcium or magnesium. Second, in vitro studies showed that the time required to reach equilibrium varied from 10 min to 3 wk among different compounds, depending upon solubility in acid and neutral solutions. Third, the relative order of effectiveness of binders in vivo was accurately predicted from theoretical and in vitro results; specifically, calcium acetate and aluminum carbonate gel were superior to calcium carbonate or calcium citrate in inhibiting dietary phosphorus absorption in normal subjects. We concluded that: (a) inhibition of phosphorus absorption by binders involves a complex interplay between chemical reactions and ion transport processes in the stomach and small intestine; (b) theoretical and in vitro studies can identify potentially better in vivo phosphorus binders; and (c) calcium acetate, not previously used for medical purposes, is approximately as efficient as aluminum carbonate gel and more efficient as a phosphorus binder than other currently used calcium salts.
Platelets, and a variety of other cells, rapidly hydrolyze the phosphoinositides in response to stimulation by agonists. One of the products of hydrolysis of phosphatidylinositol 4,5-diphosphate is inositol 1,4,5-trisphosphate, which recently has been suggested to mediate intracellular Ca2+ mobilization. We have found that human platelets contain an enzyme that degrades inositol 1,4,5-trisphosphate. We have isolated this soluble enzyme and find that it hydrolyzes the 5-phosphate of inositol 1,4,5-trisphosphate (Km = 30 microM, Vmax = 5.3 microM/min/mg of protein). The products of the reaction are inositol 1,4-diphosphate and phosphate. The apparent molecular weight of the enzyme is 38,000 as determined both by gel filtration and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence and absence of 2-mercaptoethanol. This enzyme is specific for inositol 1,4,5-trisphosphate. Other water soluble inositol phosphates as well as phosphorylated sugars are not hydrolyzed, while the only inositol containing phospholipid hydrolyzed is phosphatidylinositol 4,5-diphosphate at a rate less than 1% that for inositol 4,5-trisphosphate. The inositol 1,4,5-trisphosphate 5-phosphomonoesterase requires Mg2+ for activity and is inhibited by Ca2+, Ki = 70 microM. Li+, up to 40 mM, has no effect on enzyme activity. The duration and magnitude of any inositol 1,4,5-trisphosphate response in stimulated platelets may be determined by the activity of this enzyme.
The aim of this paper was to evaluate the variations of total serum magnesium and its relations with the immunoglobulins and lymphocytes (CD + 3T and CD + 19B) after maximal exercise in sportsmen. Twelve normal male subjects, Volleyball players in the maximal category of the official Spanish league of Volleyball, volunteered for this study after having been informed of the protocol involved. Total serum proteins (TP), IgG, IgA, IgM were determined. The total number of CD3 + T lymphocytes and CD19 + B lymphocytes in peripheral blood were measured. The stress level was determined by analytical methods (Cortisol). Total serum magnesium (MgT) and ultrafiltrable serum magnesium (MgU) were determined. After maximal exercise, Mg-T increased significantly in both groups (p < 0.05) and returned, in recovery state, to levels of baseline state. In control group Mg-U remained unchanged after maximal exercise and in recovery: 62% at rest, 61.5% after exercise and 60% at recovery period. However in the elite sportsmen Mg-U decreased significantly after exercise (60.5% at rest, 52% after exercise and 56% at recovery). When applying the Wilk's Lambda test to study the effect of exercise on immunoglobulins and on serum magnesium we obtain that the behaviour of immunological parameters and serum Mg is similar in elite sportsmen and in control group, however there are no interactions between them.
In brief: Diet quality and nutrition knowledge were evaluated in 97 competitive female adolescent gymnasts. Each gymnast kept a three-day diet record and completed a questionnaire. The gymnasts averaged only 1,838 kcal per day, which is 300 kcal less than the recommended energy intake for 13-year-old girls 60 in. tall. More than 40% consumed diets that provided less than two thirds of the recommended dietary allowance for calcium, folate, vitamin B6, iron, and zinc. Their nutrition knowledge was poor; thus, a nutrition education program would be valuable for these athletes.
In brief: The patient in this case report engaged in severe and prolonged exercise (six hours of tennis daily) and suffered bouts of postexercise carpopedal spasm. She was found to have Hypomagnesemia. After receiving magnesium supplements, her symptoms abated and serum magnesium normalized.
In brief: The authors used diet recall, a food record, a written test, interviews, questionnaires, and anthropometry to examine the nutrition and weight-control practices and knowledge of 42 wrestlers from two college teams. Data were collected before, during, and after the wrestling season. During the season, many of the wrestlers did not meet two thirds of the recommended dietary allowance for calories, protein, vitamins C, A, B6, and thiamine, iron, zinc, and magnesium, though their diets were more adequate before and after the season. The wrestlers, who lacked a good understanding of nutrition, relied primarily on food restriction and dehydration to lose weight; some also used vomiting, laxatives, and diuretics.
Med. Sci. Sports Exerc., Vol. 30, No. 11, pp. 1584-1591, 1998. Magnesium (Mg) is important for regulating ion transport and cellular metabolism in all body tissues. In skeletal muscle Mg is involved in the neuromuscular activity, excitation, and muscle contraction. Mg deficiency can cause muscle weakness and muscle cramps. Less than 1% of total body Mg is found in serum, yet the serum Mg concentration is used to assess the body's Mg status.
Purpose: The purpose of this study was to determine whether an oral Mg supplementation (500 mg Mg-oxide·d-1 for 3 wk) affects exercise performance, clinical symptoms, and the Mg concentration in various body compartments in athletes with low-normal serum Mg levels (N = 10 in each group).
Methods: In a double-blind, placebo-controlled study, correlation analysis between the Mg concentration in serum, blood cells, and skeletal muscle was performed to establish a measure for muscle cell Mg.
Results: The data indicate that a 3-wk Mg supplementation did not affect exercise performance, neuromuscular activity, or muscle related symptoms. Also, the supplementation did not increase the Mg concentration in serum or any cellular compartment studied. However, in the placebo group the renal Mg clearance decreased, whereas it increased in the subjects receiving Mg supplementation. Correlation analysis revealed that serum Mg only correlated with red cell Mg and that only leukocyte Mg correlated with the nuclear magnetic resonance (NMR)-measured muscle cell Mg concentration.
Conclusions: These results indicate that Mg supplementation in athletes with low-normal serum Mg did not improve performance and failed to increase the body's Mg stores. Serum Mg appears to be a poor indicator for Mg in skeletal muscle or most other cellular compartments, but the concentration of Mg in mononuclear leukocytes might be used as an indicator of skeletal muscle Mg when NMR is not available.
The effect of potassium-magnesium-aspartate on the capacity for continuous prolonged standardized physical exercise (exercise times about 90 min) has been investigated in 6 normal young men. After administration of potassium-magnesium-aspartate the capacity for prolonged exercise increased about 50 per cent. Possible mechanisms behind this effect are discussed.
Indices of magnesium and zinc status were measured in 114 male endurance athletes and 117 healthy controls. Dietary energy, magnesium and zinc intakes, calculated from 122-item food use questionnaires for 1 month, were higher in athletes (p<0.0001). The mean intake of magnesium and zinc was at or above the Nordic recommended level in both groups. The 95% confidence interval (95% CI) for mean serum magnesium concentration was 0.81–0.85 mmol/L in both groups (p>0.05). Levels of serum zinc (95% CIs for the mean in athletes: 13.3–14.0 μmol/L, controls: 13.4–14.1 μmol/L) and erythrocyte magnesium (athletes: 6.72–7.00 μmol/g Hb, controls: 6.88–7.12 μmol/g Hb) did not differ significantly between the groups. The athletes had higher (p<0.0001) erythrocyte zinc levels (mean: 0.61 μmol/g Hb, 95% CI: 0.60–0.62) than the control group (mean: 0.58 μmol/g Hb, 95% CI: 0.57–0.59). There was a weak correlation between serum and erythrocyte magnesium: r=0.21 in athletes (p<0.05) and r=0.28 in controls (p<0.01). Correlations between dietary intakes and biochemical measures were not different from zero. In conclusion, we found no signs of altered magnesium or zinc status in athletes or controls. However, different indicators were poorly comparable on an individual level.
In a 4-yr clinical trial, effect on single-photon absorptiometric measurements of arm bones of usual intakes of energy and 14 nutrients plus vitamin-mineral supplements was studied in 99 women, aged 35-65, randomly assigned to placebo (NS) or calcium-supplemented (1.5 g)(S) groups. Cross-sectional analysis of initial bone measurements showed vitamin C (r = 0.313, p less than 0.05) and niacin (r = 0.353, p less than 0.01) correlated with ulna in postmenopausal subjects (n = 67). Longitudinal analysis of bone-change rates of postmenopausal subjects (NS + S) showed higher calcium intakes associated with lower loss rates of humerus bone-mineral content (BMC) (r = 0.360, p less than 0.01). In postmenopausal NS but not S subjects, energy, protein, calcium, phosphorus, zinc, and folate correlate significantly with change in radius BMC; high levels of intake correlated with slower loss (p less than 0.05). Several nutrients besides calcium are related to bone loss in women.
These studies demonstrate the body's capacity to minimize electrolyte losses during acute and repeated bouts of exercise and dehydration. Although there are marked shifts in water and selected ions in the exercising muscle, only during prolonged exertion is the ratio of intramuscular to extramuscular K+ significantly altered, suggesting that some modifications of the muscle cell membrane may occur. Muscle tissue not engaged in the exercise seems unaffected by the sweat lost during prolonged activity but relinquishes intracellular water shortly after work is terminated. Blood, muscle, sweat, and urine measurements before and following varied levels of dehydration demonstrate that body water lost during exercise in the heat is accomplished at the expense of larger water losses from extracellular than from intracellular compartments. Moreover, the loss of ions in sweat and urine had little effect on the K+ content of either plasma or muscle. With repeated days of dehydration and heavy exercise, plasma volume increased in proportion to an increase in body Na+ storage. At this point some mention should be made concerning the effect of this increased plasma water on the concentration of blood constiutents. Since red blood cells and hemoglobin are confined to the vascular space, both may decrease significantly as a function of the hemodilution induced by repeated days of exercise and dehydration. This may in part explain the apparent anemia reported by sports physicians among athletes undergoing intensive training. It is also possible that such hemodilution may produce low concentrations of plasma K+, which might be falsely interpreted as suggestive of a hypokalemic state. In any event, some caution should be used in the clinical interpretation of plasma concentrations of various constituents among the endurance trained athletes. In general, it seems that the large sweat losses incurred during training and marathon competition are adequately tolerated by the runner, with concomitant adjustments in the water and electrolyte distribution of the runner's body fluid compartments. Despite the sizeable excretion of ions in sweat, the runner's large caloric intake and renal conservation of Na+ minimize the threat of chronic dehydration and/or electrolyte deficiencies.
Optimum tissue levels of magnesium and potassium ions are essential to the structure and function of the myocardium. We hypothesized that an inapparent deficiency of one or both of these elements might contribute to sudden cardiac death in a susceptible person, and in this study investigated levels of these elements in the myocardium of men experiencing sudden death to determine if there was such an association. Subjects dying suddenly with ischemic heart disease had significantly lower levels of myocardial tissue magnesium and potassium than the controls (men dying of acute trauma). The four lowest potassium values were obtained for the only men in the group with a history of angina (P less than 0.0005). Three of the men with angina also had the lowest tissue magnesium levels (P less than 0.005). The intriguing finding gives support to the hypothesis.
This study examined the effect of magnesium supplementation on muscle magnesium content, on running performance during a 42-km marathon footrace, and on muscle damage and the rate of recovery of muscle function following the race. Twenty athletes were divided equally into two matched groups and were studied for 4 weeks before and 6 weeks after a marathon in a double-blind trial; the experimental group received magnesium supplement (365 mg per day) and the control group, placebo. Magnesium supplementation did not increase either muscle or serum magnesium concentrations and had no measurable effect on 42-km marathon running performance. Extra magnesium ingestion also had no influence on the extent of muscle damage or the rate of recovery of muscle function. The latter was significantly reduced immediately after the marathon but returned to normal within 1 week. Thus, magnesium supplementation in magnesium-replete subjects did not enhance performance or increase resistance to muscle damage during the race, or the rate of recovery of muscle function following the race.
An effect of diet in determining blood pressure is suggested by epidemiological studies, but the role of specific nutrients is still unsettled.
The relation of various nutritional factors with hypertension was examined prospectively among 30,681 predominantly white US male health professionals, 40-75 years old, without diagnosed hypertension. During 4 years of follow-up, 1,248 men reported a diagnosis of hypertension. Age, relative weight, and alcohol consumption were the strongest predictors for the development of hypertension. Dietary fiber, potassium, and magnesium were each significantly associated with lower risk of hypertension when considered individually and after adjustment for age, relative weight, alcohol consumption, and energy intake. When these nutrients were considered simultaneously, only dietary fiber had an independent inverse association with hypertension. For men with a fiber intake of < 12 g/day, the relative risk of hypertension was 1.57 (95% confidence interval, 1.20-2.05) compared with an intake of > 24 g/day. Calcium was significantly associated with lower risk of hypertension only in lean men. Dietary fiber, potassium, and magnesium were also inversely related to baseline systolic and diastolic blood pressure and to change in blood pressure during the follow-up among men who did not develop hypertension. Calcium was inversely associated with baseline blood pressure but not with change in blood pressure. No significant associations with hypertension were observed for sodium, total fat, or saturated, transunsaturated, and polyunsaturated fatty acids. Fruit fiber but not vegetable or cereal fiber was inversely associated with incidence of hypertension.
These results support hypotheses that an increased intake of fiber and magnesium may contribute to the prevention of hypertension.
The aim of this paper was investigate the effects of high-intensity exercise on plasmatic and erythrocytic Mg levels in men. Twelve normal male volunteers participated in this study. The tests were performed on a cycle-ergometer (Monark). The exercise programs consisted of: 1) triangular progressive test (TPT); 2) interval endurance test (IET), of 45 min duration; and 3) maximal subtained test (MST), consisting of a maximal level, at 100% of MTP, for at least 7 min. The percent change in plasma volume (%PV) after exercise was calculated. Magnesium levels in plasma and erythrocytes were measured by atomic absorption spectrophotometry. No significant differences in the absolute Mg concentration of plasma were noted for the three maximal exercises. The percentage increase in plasma Mg concentrations was about 5-7%; however, percent decrease of PV was more important (13-16%). Erythrocytic Mg levels were increased after all maximal exercises (TPT, IET, and MST), although absolute Mg concentrations were not significantly different.
Unlabelled:
This study investigated the effects of dietary magnesium (Mg) on strength development during a double-blind, 7-week strength training program in 26 untrained subjects (14 = control, C and 12 = Mg supplemented, M), 18-30 years old. Subjects' 3-day diet records were analyzed and Mg content was calculated. C received a placebo and M received a supplement (Mg oxide) to bring Mg intake, including diet, to 8 mg/kg body weight/day. Body composition was assessed with bioelectrical impedance. Pre and post quadriceps torque (T) measurements were made with an Orthotron at 120 deg/sec. Each subject performed three sets of 10 reps, leg press and leg extension, three times/week. Both groups gained strength, however, results indicated a significant (p less than 0.05) increase for the M group compared to the C group in absolute T, relative T adjusted for body weight (T/BWT), and relative T adjusted for lean body mass (T/LBM) when pre values were used as the covariate. M was consistently greater than C (T: 211 vs 174 Nm; T/BWT: 3.07 vs 2.58 Nm/kg; T/LBM: 3.84 vs 3.36 Nm/kg).
Conclusion:
Significant differences in T gains after strength training were demonstrated in M vs C. Mg's role may be at the ribosomal level in protein synthesis.
1. The effect of myoplasmic Mg2+ on Ca2+ release was examined in mechanically skinned skeletal muscle fibres, in which the normal voltage-sensor control of Ca2+ release is preserved. The voltage sensors could be activated by depolarizing the transverse tubular (T-) system by lowering the [K+] in the bathing solution. 2. Fibres spontaneously contracted when the free [Mg2+] was decreased from 1 to 0.05 mM, with no depolarization or change of total ATP, [Ca2+] or pH (pCa 6.7, 50 microM-EGTA). After such a 'low-Mg2+ response' the sarcoplasmic reticulum (SR) was depleted of Ca2+ and neither depolarization nor caffeine (2 mM) could induce a response, unless the [Mg2+] was raised and the SR reloaded with Ca2+. Exposure to 0.05 mM-Mg2+ at low [Ca2+] (2 mM-free EGTA, pCa greater than 8.7) also induced Ca2+ release and depleted the SR. 3. The response to low [Mg2+] was unaffected by inactivation of the voltage sensors, but was completely blocked by 2 microM-Ruthenium Red indicating that it involved Ca2+ efflux through the normal Ca2+ release channels. 4. In the absence of ATP (and creatine phosphate), complete removal of Mg2+ (i.e. no added Mg2+ with 1 mM-EDTA) did not induce Ca2+ release. Depolarization in the absence of Mg2+ and ATP also did not induce Ca2+ release. 5. Depolarization in 10 mM-Mg2+ (pCa 6.7, 50 microM-EGTA, 8 mM-total ATP) did not produce any response. In the presence of 1 mM-EGTA to chelate most of the released Ca2+, depolarizations in 10 mM-Mg2+ did not noticeably deplete the SR of Ca2+, whereas a single depolarization in 1 mM-Mg2+ (and 1 mM-EGTA) resulted in marked depletion. Depolarization in the presence of D600 and 10 mM-Mg2+ produced use-dependent 'paralysis', indicating that depolarization in 10 mM-Mg2+ did indeed activate the voltage sensors. 6. Depolarization in the presence of 10 mM-Mg2+ and 25 microM-ryanodine neither interfered with the normal voltage control of Ca2+ release nor caused depletion of the Ca2+ in the SR even after returning to 1 mM-Mg2+ for 1 min, indicating that few if any of the release channels had been opened by the depolarization.(ABSTRACT TRUNCATED AT 400 WORDS)
Renal magnesium wasting is an important cause of hypomagnesemia observed in hospitalized patients. The purpose of this review is to present an index case of symptomatic hypomagnesemia associated with renal magnesium wasting during capreomycin therapy, and to survey the available literature regarding the various therapeutic agents associated with the causation of this syndrome. Finally, we have considered the pathophysiologic mechanisms that may contribute to the development of the multiple electrolyte abnormalities observed in these patients, and have outlined the current strategies to treat this syndrome.
Magnesium absorption has been studied in both humans and animals under diverse experimental conditions. As a result, the data often appear confusing and conflicting. In this review we attempt to summarize information concerning Mg absorption and, where possible, to reconcile apparently conflicting observations. Most studies suggest that Mg is absorbed predominantly in the distal intestine. At usual Mg intakes, Mg absorption occurs primarily by intercellular diffusional and solvent drag mechanisms. There is evidence for a saturable component of Mg absorption in the small intestine and the descending colon that is important at low dietary Mg intakes. Pharmacological doses of vitamin D increase Mg absorption in both vitamin D-deficient and vitamin D-replete animals. A substantial amount of Mg absorption, however, occurs independent of vitamin D. In addition, vitamin D may reduce Mg retention through increases in urinary Mg excretion. Intestinal interactions between Mg and calcium or phosphate have been demonstrated in both humans and animals. The nature of these interactions cannot be readily explained by data currently available.
Daily intakes of sodium, potassium, calcium, phosphorus, magnesium, iron, zinc, selenium, iodine, copper, and manganese for eight age-sex groups are presented for 1982 to 1989. Compared with the intakes recommended by the National Academy of Sciences, sodium intakes (which did not include discretionary salt) exceeded the estimated minimum requirement; intakes of potassium, phosphorus, selenium, and iodine were adequate for all groups; and copper intakes were low (less than 80% of the suggested intake) for all groups. In addition, calcium, magnesium, iron, and manganese were low in the diets of teenage girls; calcium, magnesium, and iron were low in the diets of adult women; calcium, magnesium, and zinc were low in the diets of older women; calcium and zinc were low in the diets of 2-year-olds; and magnesium was low in the diets of teenage boys and older men. The primary food group source for each element was dairy products for potassium, calcium, phosphorus, magnesium, and iodine; grain products for sodium, iron, and manganese; and animal flesh for zinc, selenium, and copper.
Magnesium is the second most abundant intracellular cation. It is essential for a wide variety of metabolically important reactions, in particular those involving ATP. Hypomagnesaemia is surprisingly common in hospital populations but is sometimes either undetected or overlooked.
Serum magnesium concentrations provide a guide to magnesium status but while hypomagnesaemia is a reliable indicator of magnesium deficiency, normomagnesaemia does not exclude magnesium depletion. A wide variety of conditions predispose to magnesium depiction. Clinical magnesium deficiency has potentially fatal consequences in vulnerable groups of patients and should be excluded in all such cases. Magnesium deficiency may result in hypokalemia, hypocalcaemia or other disturbances of electrolyte homeostasis, refractory cardiac arrhythmias, or increased sensitivity to digoxin.
The capacity to measure serum and urine magnesium concentrations rapidly, regularly and reliably should be part of the repertoire of all clinical chemistry laboratories involved in the care of critically ill patients.
Exercise under certain conditions appears to lead to Mg depletion and may worsen a state of deficiency when Mg intake is inadequate. Whereas hypermagnesaemia occurs following short term high intensity exercise as the consequence of a decrease in plasma volume and a shift of cellular magnesium resulting from acidosis, prolonged submaximal exercise is accompanied by hypomagnesaemia. Discordant findings on the effect of physical exercise on erythrocyte concentrations have been reported. A mechanism for the observed decrease in plasma magnesium concentration after long term physical exercise could be a shift of Mg into the erythrocyte. However, in several studies the decrease in plasma Mg was not accompanied by an increase in RBC Mg, but a decrease in cellular Mg was observed. Urinary Mg losses during an endurance event could play a role in this depletion but are often reduced, reflecting renal compensation. Loss of Mg by sweating takes place only when there is a failure in sweat homeostasis, a situation which arises when exercise is made in conditions of damp atmosphere and high temperature. Stress caused by physical exercise is capable of inducing Mg deficit by various mechanisms. A possible explanation for decreased plasma Mg concentration during long endurance events is the effect of lipolysis. Since fatty acids are mobilized for muscle energy, lipolysis would cause a decrease in plasma Mg. In developed countries Mg intake is often marginal and sport is a factor which is particularly likely to expose athletes to Mg deficit through metabolic depletion linked to exercise itself, which can only aggravate the consequences of a frequent marginal deficiency. Mg depletion and deficiency therefore play a role in the pathophysiology of physical exercise. Experiments on animals have shown that severe Mg deficiency reduces physical performance and in particular the efficiency of energy metabolism. These data, however, do not correspond to those of marginal deficiency most commonly observed in humans. Clinical symptomatology, both in athletes and in other patients, is dominated by the symptomatology of neuromuscular hyperexcitability. Medical authorities in sport have enforced obligatory tests for latent tetany in athletes, with ionic assessment. The effects of the correction of magnesium deficiency are judged from clinical signs, Chvosteck sign, electromyogram and echocardiogram findings and plasma Mg, erythrocyte and urine analysis. These may also be complemented by cardiac and respiratory investigations after exercise. The positive effects (analysis after a minimum period of one month) of a simple oral supplement administered in physiological doses (5 mg/kg body weight/day) provides evidence for the existence of a deficiency.(ABSTRACT TRUNCATED AT 400 WORDS)
We examined whether healthy young swimmers improved performance during emotional and physical stress testing in the laboratory or during competition. Twenty four well trained healthy Caucasian pupils (14 boys and 10 girls, means = 16 years) were randomly treated either with 20 mmol Mg-aspartate-HCl/d or placebo for 3 months. After Mg supplementation serum Mg increased from 0.85 +/- 0.03 to 0.89 +/- 0.06 mmol/litre (P less than 0.05). Mg in red blood cells remained unchanged (4.79 +/- 0.35 mmol/kg dry weight before supplementation and 4.96 +/- 0.27 three months later, P = 0.32) whereas no increase in serum Mg or Mg in red blood cells was found in subjects who received placebo. Student's t test and analyses of variance revealed no significant differences in performance data either in the laboratory or during competition after supplementation with Mg.
Canine cerebellar membranes were fractionated by differential centrifugation into a crude mitochondrial pellet (P2) and a crude microsomal pellet (P3). The effect of Mg2+ on inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release and [3H]IP3 binding was assessed. Mg2+ inhibited IP3-induced Ca2+ release in a concentration-dependent manner. Mg2+ influenced both the extent of IP3-induced Ca2+ release and the apparent affinity for IP3. A 10-fold change of free Mg2+ (from approximately 30 to approximately 300 microM) reduced the extent of Ca2+ release by two- to threefold and shifted the apparent Michaelis constant from approximately 0.5 to approximately 0.9 microM IP3. Thus Mg2+ seemed to be noncompetitive inhibitor of IP3-induced Ca2+ release. Mg2+ also inhibited Ca2+ release elicited by glycerophosphoinositol 4,5-bisphosphate, a poorly metabolized analogue of IP3. Mg2+ and heparin sodium were shown to be additive inhibitors of IP3-induced Ca2+ release. Mg2+ inhibited [3H]IP3 binding under experimental conditions designed to minimize IP3 hydrolysis. Scatchard plots indicated that 0.5 mM free Mg2+ reduced maximum binding from 10.9 to 3.5 pmol IP3 bound/mg protein and increased the dissociation constant from 136 to 227 nM. The modulation of [3H]IP3 binding and IP3-induced Ca2+ release by Mg2+ could be physiologically relevant.
Erythrocitary and serum magnesium (Mg) were determined in a group of 11 well-trained athletes before and after a 25-km running race, and in a group of 30 sedentary controls. The significant increase of mean erythrocitary Mg (EMg) concentration observed in the athletes after physical strain (2.58 +/- 0.34 mEq/l before, 3.10 +/- 0.45 mEq/l after the race: significance level = 5%) leads to the assumption that the possible Mg uptake is effected by the red blood cell to enhance some enzymatic reactions. The decrease of mean serum Mg concentration observed in the same subjects after the effort (1.70 +/- 0.14 mEq/l before, 1.64 +/- 0.15 mEq/l after the race) is not significant. The difference between mean Mg concentrations observed in the athletes' group before the race and in the sedentary group (EMg: 2.58 +/- 0.34 mEq/l in athletes, 3.67 +/- 0.38 mEq/l in sedentaries, significance level = 1%; serum Mg: 1.70 +/- 0.14 mEq/l in athletes, 1.96 +/- 0.15 mEq/l in sedentaries, significance level = 1%) suggests that athletes suffer from a Mg deficiency, partially due to physical exercise. The two hypotheses and the possible causes of the observed phenomena are discussed.
Increasing information on the potentially serious risks of potassium and magnesium depletion associated with diuretic therapy demands a clinical focus on understanding the factors involved and on methods for preventing these electrolyte deficiencies. Data suggest that serum potassium and magnesium levels may be normal in the presence of tissue depletion, but decreases in serum levels are almost always associated with tissue and whole-body depletion of these electrolytes in patients in whom such depletion cannot be risked. Ventricular ectopy has also been associated with depletion of potassium and magnesium, which may explain the increased risk of sudden unexpected death in hypertensive patients. Any clinician who treats hypertension or congestive heart failure must consider whether to replete potassium and magnesium in patients already receiving diuretic therapy, or, better still, consider how to prevent depletion of these electrolytes in patients in whom such depletion cannot be risked. If prevention is selected, the clinician must then evaluate the data on available diuretic combinations for efficacy in electrolyte conservation, bioavailability, and dosage convenience. The combination of triamterene and hydrochlorothiazide (Maxzide, 75 mg triamterene/50 mg hydrochlorothiazide) has demonstrated electrolyte conservation, with bioavailability and dosage convenience.