The effects of magnesium supplementation on exercise performance

Effects of magnesium supplementation on muscle soreness in different type of physical activities: a systematic review

BACKGROUND

Magnesium is a micronutrient and an intracellular cation responsible for different biochemical reactions involved in energy production and storage, control of neuronal and vasomotor activity, cardiac excitability, and muscle contraction. Magnesium deficiency may result in impaired physical performance. Moreover, magnesium plays an important role on delayed onset muscle soreness after training. Thus, physically active individuals and sport specialists have to pay attention to magnesium supplementation (MgS). However, the type, timing and dosage of magnesium intake are not well elucidated yet. Hence, we aimed to systematically review the literature regarding the effects of MgS on muscle soreness in physically active individuals. We focused exclusively on MgS, excluding those studies in which magnesium was administered together with other substances.

METHODS

Three electronic databases and literature sources (PUBMED, SCOPUS and Web of Sciences-Core Collection) were searched, in accordance with PRISMA guidelines. After the database search, 1254 articles were identified, and after excluding duplicates, 960 articles remained. Among these, 955 were excluded following the title and abstract screening. The remaining 5 articles were screened in full text and 4 study met the eligibility criteria.

RESULTS

These studies showed that MgS reduced muscle soreness, improved performance, recovery and induced a protective effect on muscle damage.

CONCLUSION

To reach these positive effects, individuals engaged in intense exercise should have a Mg requirement 10-20% higher than sedentary people, to be taken in capsules and 2 h before training. Moreover, it is suggested to maintain magnesium levels in the recommended range during the off-season.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42024501822.

Nutrients with Antioxidant Properties and Their Effects on Lower-Limb Ulcers: A Systematic Review

Chronic lower-limb ulcers (LLUs) are ulcers that fail to proceed through an orderly and timely process to produce anatomic and functional integrity. LLUs reduce the quality of life of affected individuals and are a public health problem. The treatment options include medications or surgery. Nutrition therapy is an important adjunct to improve the clinical picture and healing of LLUs. Considering that nutrients with antioxidant properties can improve the process of tissue healing, this systematic review aimed to evaluate the efficacy of antioxidant nutrient supplementation in the treatment of LLUs through randomized clinical trials. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses and the Cochrane Handbook for Systematic Reviews of Interventions. The guiding question was-can antioxidant nutrients help in the treatment of chronic LLUs? In total, 1184 articles were found when searching for antioxidant nutrients associated with the most common causes of LLUs. Fourteen articles were included in this review after removing duplicates, studies with topical and/or venous use of antioxidants, and articles published in other languages, except English. Omega-3 fatty acids, magnesium, zinc, vitamins A, C, D, and resveratrol along with probiotics positively improved the ulcer healing. These effects were more significant when there was initially a deficiency of the respective supplemented nutrients. Therefore, correcting and maintaining an adequate nutritional status can improve ulcer healing and contribute to the clinical treatment of patients with LLUs.

Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels

This study aimed to investigate the short-term effects of three magnesium (Mg) dietary supplements containing mineral immediately available for absorption on Mg biochemical status indices (ionized and total Mg), as well as their effects on electrolytes levels in healthy female young adults (n = 61). After a 10-days intervention period supplementation with powder/granulate containing Mg oxide led to an increase in both ionized Mg concentration and % in total Mg in comparison with the baseline. Supplementation with Mg citrate was associated with the significant increase in % of ionized fraction and decrease in serum total Mg concentration. By contrast, among participants consuming Mg carbonate in the form of effervescent tablets ionized Mg concentration and % in total Mg decreased, without detectable changes in serum total Mg. In conclusion, after the short-term supplementation period, Mg oxide demonstrated superior bioavailability compared to the other examined Mg supplements without affecting other minerals' levels.

MR-PheWAS for the causal effects of serum magnesium on multiple disease outcomes in Caucasian descent

Magnesium is integral to many physiological processes, whereas 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. In addition, 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.

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MR-PheWAS implicates a causal role of serum Mg in 11 disease groups/outcomes

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Our study indicates gender-specific effects of 9 disease groups/outcomes

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Mg intervention may promote cataracts treatments through the DCDC1 and PAX6 genes

Effects of Magnesium Supplementation on Muscle Soreness and Performance

Reno, AM, Green, M, Killen, LG, O'Neal, EK, Pritchett, K, and Hanson, Z. Effects of magnesium supplementation on muscle soreness and performance. J Strength Cond Res XX(X): 000-000, 2020-This double-blind, between-group study examined effects of magnesium (Mg) supplementation (350 mg·d, 10 days) on muscle soreness and performance. College-aged male (n = 9) and female (n = 13) subjects completed baseline and posttreatment eccentric bench press sessions inducing fatigue/soreness followed by performance sessions (total volume and repetitions to failure [RTF] [65, 75, and 85% of 1 repetition maximum]) 48 hours later with perceptual measures. Subjects estimated soreness using a Delayed Onset of Muscle Soreness scale by striking a vertical line on a 6-cm horizontal line (at 24, 36, and 48 hours post trial) from 0-no soreness to 6-intolerable soreness. Results are presented as means ± SD (alpha ≤0.05). Mg significantly reduced (∼1-2 units lower on a 6-point scale) muscle soreness from the baseline eccentric to postintervention trial 24, 36, and 48 hours with no significant change for placebo (Pla) group. Performance approached significance for total RTF (p = 0.06) and 65 and 75% RTF (p = 0.08) (Mg vs. Pla). Perceptual responses for session rating of perceived exertion and acute rating of perceived exertion were significant for Mg (5.1 ± 2.4 to 4.1 ± 2.0) vs. Pla (5.0 ± 1.8 to 5.5 ± 1.6). Perceived recovery after supplementation was improved vs. baseline for Mg (5.4 ± 2.2 to 7.5 ± 2.3) but not for Pla (6.2 ± 2.4 to 7.2 ± 3.3). Results show significantly reduced muscle soreness, session rating of perceived exertion, acute rating of perceived exertion, and improved perceived recovery after Mg (vs. Pla) supplementation and some evidence for positive performance impact.

Circulating Ionized Magnesium as a Measure of Supplement Bioavailability: Results from a Pilot Study for Randomized Clinical Trial

Oral supplementation may improve the dietary intake of magnesium, which has been identified as a shortfall nutrient. We conducted a pilot study to evaluate appropriate methods for assessing responses to the ingestion of oral magnesium supplements, including ionized magnesium in whole blood (iMg²⁺) concentration, serum total magnesium concentration, and total urinary magnesium content. In a single-blinded crossover study, 17 healthy adults were randomly assigned to consume 300 mg of magnesium from MgCl₂ (ReMag^®, a picosized magnesium formulation) or placebo, while having a low-magnesium breakfast. Blood and urine samples were obtained for the measurement of iMg²⁺, serum total magnesium, and total urine magnesium, during 24 h following the magnesium supplement or placebo dosing. Bioavailability was assessed using area-under-the-curve (AUC) as well as maximum (C_max) and time-to-maximum (T_max) concentration. Depending on normality, data were expressed as the mean ± standard deviation or median (range), and differences between responses to MgCl₂ or placebo were measured using the paired t-test or Wilcoxon signed-rank test. Following MgCl₂ administration versus placebo administration, we observed significantly greater increases in iMg²⁺ concentrations (AUC = 1.51 ± 0.96 vs. 0.84 ± 0.82 mg/dL•24h; C_max = 1.38 ± 0.13 vs. 1.32 ± 0.07 mg/dL, respectively; both p < 0.05) but not in serum total magnesium (AUC = 27.00 [0, 172.93] vs. 14.55 [0, 91.18] mg/dL•24h; C_max = 2.38 [1.97, 4.01] vs. 2.24 [1.98, 4.31] mg/dL) or in urinary magnesium (AUC = 201.74 ± 161.63 vs. 139.30 ± 92.84 mg•24h; C_max = 26.12 [12.91, 88.63] vs. 24.38 [13.51, 81.51] mg/dL; p > 0.05). Whole blood iMg²⁺ may be a more sensitive measure of acute oral intake of magnesium compared to serum and urinary magnesium and may be preferred for assessing supplement bioavailability.

Impact of Magnesium Supplementation in Muscle Damage of Professional Cyclists Competing in a Stage Race

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.

Predicting and Testing Bioavailability of Magnesium Supplements

Despite the presumption of the beneficial effects of magnesium supplementation, little is known about the pharmacokinetics of different magnesium formulations. We aimed to investigate the value of two in vitro approaches to predict bioavailability of magnesium and to validate this in subsequent in vivo testing. In vitro assessment of 15 commercially available magnesium formulations was performed by means of a Simulator of the Human Intestinal Microbial Ecosystem (SHIME^®) and by dissolution tests. Two magnesium formulations with contrasting bioavailability prediction from both in vitro tests (best vs. worst) were selected for in vivo testing in 30 subjects. In vivo bioavailability was compared following one acute ingestion by monitoring blood magnesium concentrations up to 6 h following intake. The in vitro tests showed a very wide variation in absorption and dissolution of the 15 magnesium products. In the in vivo testing, a significant different serum magnesium absorption profile was found up to 4 h following supplement ingestion for the two supplements with opposing in vitro test results. Moreover, maximal serum magnesium increase and total area under the curve were significantly different for both supplements (+6.2% vs. +4.6% and 6.87 vs. 0.31 mM.min, respectively). Collectively, poor bioaccessibility and bioavailability in the SHIME model clearly translated into poor dissolution and poor bioavailability in vivo. This provides a valid methodology for the prediction of in vivo bioavailability and effectiveness of micronutrients by specific in vitro approaches.

The Role of Mineral and Trace Element Supplementation in Exercise and Athletic Performance: A Systematic Review

Minerals and trace elements (MTEs) are micronutrients involved in hundreds of biological processes. Deficiency in MTEs can negatively affect athletic performance. Approximately 50% of athletes have reported consuming some form of micronutrient supplement; however, there is limited data confirming their efficacy for improving performance. The aim of this study was to systematically review the role of MTEs in exercise and athletic performance. Six electronic databases and grey literature sources (MEDLINE; EMBASE; CINAHL and SportDISCUS; Web of Science and clinicaltrials.gov) were searched, in accordance with PRISMA guidelines. Results: 17,433 articles were identified and 130 experiments from 128 studies were included. Retrieved articles included Iron (n = 29), Calcium (n = 11), Magnesium, (n = 22), Phosphate (n = 17), Zinc (n = 9), Sodium (n = 15), Boron (n = 4), Selenium (n = 5), Chromium (n = 12) and multi-mineral articles (n = 5). No relevant articles were identified for Copper, Manganese, Iodine, Nickel, Fluoride or Cobalt. Only Iron and Magnesium included articles of sufficient quality to be assigned as 'strong'. Currently, there is little evidence to support the use of MTE supplementation to improve physiological markers of athletic performance, with the possible exception of Iron (in particular, biological situations) and Magnesium as these currently have the strongest quality evidence. Regardless, some MTEs may possess the potential to improve athletic performance, but more high quality research is required before support for these MTEs can be given. PROSPERO preregistered (CRD42018090502).

Supplements with purported effects on muscle mass and strength

PURPOSE

Several supplements are purported to promote muscle hypertrophy and strength gains in healthy subjects, or to prevent muscle wasting in atrophying situations (e.g., ageing or disuse periods). However, their effectiveness remains unclear.

METHODS

This review summarizes the available evidence on the beneficial impacts of several popular supplements on muscle mass or strength.

RESULTS

Among the supplements tested, nitrate and caffeine returned sufficient evidence supporting their acute beneficial effects on muscle strength, whereas the long-term consumption of creatine, protein and polyunsaturated fatty acids seems to consistently increase or preserve muscle mass and strength (evidence level A). On the other hand, mixed or unclear evidence was found for several popular supplements including branched-chain amino acids, adenosine triphosphate, citrulline, β-Hydroxy-β-methylbutyrate, minerals, most vitamins, phosphatidic acid or arginine (evidence level B), weak or scarce evidence was found for conjugated linoleic acid, glutamine, resveratrol, tribulus terrestris or ursolic acid (evidence level C), and no evidence was found for other supplements such as ornithine or α-ketoglutarate (evidence D). Of note, although most supplements appear to be safe when consumed at typical doses, some adverse events have been reported for some of them (e.g., caffeine, vitamins, α-ketoglutarate, tribulus terrestris, arginine) after large intakes, and there is insufficient evidence to determine the safety of many frequently used supplements (e.g., ornithine, conjugated linoleic acid, ursolic acid).

CONCLUSION

 In summary, despite their popularity, there is little evidence supporting the use of most supplements, and some of them have been even proven ineffective or potentially associated with adverse effects.

Preventive effect of oral magnesium in postmastectomy pain: protocol for a randomised, double-blind, controlled clinical trial

INTRODUCTION

Breast cancer affects 1 in 10 women worldwide, and mastectomy is a cause of chronic pain with neuropathic characteristics. N-methyl-D-aspartate receptor (NMDAR) antagonists such as ketamine, memantine, dextromethorphan or magnesium are used to treat refractory pain by blocking NMDAR. Oral memantine has been shown to prevent postmastectomy pain and cognitive impact and to maintain quality of life. Likewise, the present study is intended to assess the preventive effect of oral magnesium, administered ahead of mastectomy, on the development of neuropathic pain. As a physiological blocker of NMDAR, magnesium could be an interesting candidate to prevent postoperative pain and associated comorbidities, including cognitive and emotional disorders, multiple analgesic consumption and impaired quality of life.

METHODS AND ANALYSIS

A randomised double-blind controlled clinical trial (NCT03063931) will include 100 women with breast cancer undergoing mastectomy at the Oncology Hospital, Clermont-Ferrand, France. Magnesium (100 mg/day; n=50) or placebo (n=50) will be administered for 6 weeks, starting 2 weeks before surgery. Intensity of pain, cognitive and emotional function and quality of life will be assessed by questionnaires. The primary endpoint is pain intensity on a 0-10 numerical rating scale at 1 month postmastectomy. Data analysis will use mixed models; all tests will be two-tailed, with type-I error set at α=0.05.

ETHICS AND DISSEMINATION

The study protocol and informed consent form were approved in December 2016 by the French Research Ethics Committee (South East VI Committee). Results will be communicated in various congresses and published in international publications.

TRIAL REGISTRATION NUMBER

NCT03063931.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-Metabolic Disease or Disturbed Homeostasis due to Focal Inflammation in the Hypothalamus?

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disease characterized by debilitating fatigue, lasting for at least 6 months, with associated malaise, headaches, sleep disturbance, and cognitive impairment, which severely impacts quality of life. A significant percentage of ME/CFS patients remain undiagnosed, mainly due to the complexity of the disease and the lack of reliable objective biomarkers. ME/CFS patients display decreased metabolism and the severity of symptoms appears to be directly correlated to the degree of metabolic reduction that may be unique to each individual patient. However, the precise pathogenesis is still unknown, preventing the development of effective treatments. The ME/CFS phenotype has been associated with abnormalities in energy metabolism, which are apparently due to mitochondrial dysfunction in the absence of mitochondrial diseases, resulting in reduced oxidative metabolism. Such mitochondria may be further contributing to the ME/CFS symptomatology by extracellular secretion of mitochondrial DNA, which could act as an innate pathogen and create an autoinflammatory state in the hypothalamus. We propose that stimulation of hypothalamic mast cells by environmental, neuroimmune, pathogenic and stress triggers activates microglia, leading to focal inflammation in the brain and disturbed homeostasis. This process could be targeted for the development of novel effective treatments.

Can Magnesium Enhance Exercise Performance?

Magnesium (Mg) is an essential mineral that plays a critical role in the human body. It takes part in the process of energy metabolism and assists the maintenance of normal muscle function. A number of studies evaluated the association between Mg status/supplementation and exercise performance and found that the need for Mg increased as individuals’ physical activity level went up. Animal studies indicated that Mg might improve exercise performance via enhancing glucose availability in the brain, muscle and blood; and reducing/delaying lactate accumulation in the muscle. The majority of human studies focused on physiological effects in blood pressure, heart rate and maximal oxygen uptake (VO₂ max), rather than direct functional performances. Some cross-sectional surveys demonstrated a positive association between Mg status and muscle performance, including grip strength, lower-leg power, knee extension torque, ankle extension strength, maximal isometric trunk flexion, rotation, and jumping performance. Additionally, findings from intervention studies showed that Mg supplementation might lead to improvements in functional indices such as quadriceps torque. Moreover, Mg supplementation could improve gait speed and chair stand time in elderly women. This comprehensive review summarized the literature from both animal and human studies and aimed to evaluate scientific evidence on Mg status/supplementation in relation to exercise performance.

Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: A pilot study

Background

Oral magnesium supplementation is commonly used to support a low magnesium diet. This investigation set out to determine whether magnesium in a cream could be absorbed transdermally in humans to improve magnesium status.

Methods and findings

In this single blind, parallel designed pilot study, n = 25 participants (aged 34.3+/-14.8y, height 171.5+/-11cm, weight 75.9 +/-14 Kg) were randomly assigned to either a 56mg/day magnesium cream or placebo cream group for two weeks. Magnesium serum and 24hour urinary excretion were measured at baseline and at 14 days intervention. Food diaries were recorded for 8 days during this period. Mg test and placebo groups’ serum and urinary Mg did not differ at baseline. After the Mg²⁺ cream intervention there was a clinically relevant increase in serum magnesium (0.82 to 0.89 mmol/l,p = 0.29) that was not seen in the placebo group (0.77 to 0.79 mmol/L), but was only statistically significant (p = 0.02)) in a subgroup of non-athletes. Magnesium urinary excretion increased from baseline slightly in the Mg²⁺ group but with no statistical significance (p = 0.48). The Mg²⁺ group showed an 8.54% increase in serum Mg²⁺ and a 9.1% increase in urinary Mg²⁺ while these figures for the placebo group were smaller, i.e. +2.6% for serum Mg²⁺ and -32% for urinary Mg^2+. In the placebo group, both serum and urine concentrations showed no statistically significant change after the application of the placebo cream.

Conclusion

No previous studies have looked at transdermal absorbency of Mg²⁺ in human subjects. In this pilot study, transdermal delivery of 56 mg Mg/day (a low dose compared with commercial transdermal Mg²⁺ products available) showed a larger percentage rise in both serum and urinary markers from pre to post intervention compared with subjects using the placebo cream, but statistical significance was achieved only for serum Mg²⁺ in a subgroup of non-athletes. Future studies should look at higher dosage of magnesium cream for longer durations.

Trial registration

ISRCTN registry ID No. ISRTN15136969

The effect of acute vs chronic magnesium supplementation on exercise and recovery on resistance exercise, blood pressure and total peripheral resistance on normotensive adults

Background

Magnesium supplementation has previously shown reductions in blood pressure of up to 12 mmHg. A positive relationship between magnesium supplementation and performance gains in resistance exercise has also been seen. However, no previous studies have investigated loading strategies to optimise response. The aim of this study was to assess the effect of oral magnesium supplementation on resistance exercise and vascular response after intense exercise for an acute and chronic loading strategy on a 2-day repeat protocol.

Methods

The study was a randomised, double-blind, cross-over design, placebo controlled 2 day repeat measure protocol (n = 13). Intense exercise (40 km time trial) was followed by bench press at 80% 1RM to exhaustion, with blood pressure and total peripheral resistance (TPR) recorded. 300 mg/d elemental magnesium was supplemented for either a 1 (A) or 4 (Chr) week loading strategy. Food diaries were recorded.

Results

Dietary magnesium intake was above the Reference Nutrient Intake (RNI) for all groups. Bench press showed a significant increase of 17.7% (p = 0.031) for A on day 1. On day 2 A showed no decrease in performance whilst Chr showed a 32.1% decrease. On day 2 post-exercise systolic blood pressure (SBP) was significantly lower in both A (p = 0.0.47) and Chr (p = 0.016) groups. Diastolic blood pressure (DBP) showed significant decreases on day 2 solely for A (p = 0.047) with no changes in the Chr. TPR reduced for A on days 1 and 2 (p = 0.031) with Chr showing an increase on day 1 (p = 0.008) and no change on day 2.

Conclusion

There was no cumulative effect of Chr supplementation compared to A. A group showed improvement for bench press concurring with previous research which was not seen in Chr. On day 2 A showed a small non-significant increase but not a decrement as expected with Chr showing a decrease. DBP showed reductions in both Chr and A loading, agreeing with previous literature. This is suggestive of a different mechanism for BP reduction than for muscular strength. TPR showed greater reductions with A than Chr, which would not be expected as both interventions had reductions in BP, which is associated with TPR.

Effect of oral magnesium supplementation on physical performance in healthy elderly women involved in a weekly exercise program: a randomized controlled trial

BACKGROUND

Magnesium deficiency is associated with poor physical performance, but no trials are available on how magnesium supplementation affects elderly people's physical performance.

OBJECTIVE

The aim of our study was to investigate whether 12 wk of oral magnesium supplementation can improve physical performance in healthy elderly women.

DESIGN

In a parallel-group, randomized controlled trial, 139 healthy women (mean ± SD age: 71.5 ± 5.2 y) attending a mild fitness program were randomly allocated to a treatment group (300 mg Mg/d; n = 62) or a control group (no placebo or intervention; n = 77) by using a computer-generated randomization sequence, and researchers were blinded to their grouping. After assessment at baseline and again after 12 wk, the primary outcome was a change in the Short Physical Performance Battery (SPPB); secondary outcomes were changes in peak torque isometric and isokinetic strength of the lower limbs and handgrip strength.

RESULTS

A total of 124 participants allocated to the treatment (n = 53) or control (n = 71) group were considered in the final analysis. At baseline, the SPPB scores did not differ between the 2 groups. After 12 wk, the treated group had a significantly better total SPPB score (Δ = 0.41 ± 0.24 points; P = 0.03), chair stand times (Δ = -1.31 ± 0.33 s; P < 0.0001), and 4-m walking speeds (Δ = 0.14 ± 0.03 m/s; P = 0.006) than did the control group. These findings were more evident in participants with a magnesium dietary intake lower than the Recommended Dietary Allowance. No significant differences emerged for the secondary outcomes investigated, and no serious adverse effects were reported.

CONCLUSIONS

Daily magnesium oxide supplementation for 12 wk seems to improve physical performance in healthy elderly women. These findings suggest a role for magnesium supplementation in preventing or delaying the age-related decline in physical performance.

Magnesium in disease prevention and overall health

Magnesium is the fourth most abundant mineral and the second most abundant intracellular divalent cation and has been recognized as a cofactor for >300 metabolic reactions in the body. Some of the processes in which magnesium is a cofactor include, but are not limited to, protein synthesis, cellular energy production and storage, reproduction, DNA and RNA synthesis, and stabilizing mitochondrial membranes. Magnesium also plays a critical role in nerve transmission, cardiac excitability, neuromuscular conduction, muscular contraction, vasomotor tone, blood pressure, and glucose and insulin metabolism. Because of magnesium's many functions within the body, it plays a major role in disease prevention and overall health. Low levels of magnesium have been associated with a number of chronic diseases including migraine headaches, Alzheimer's disease, cerebrovascular accident (stroke), hypertension, cardiovascular disease, and type 2 diabetes mellitus. Good food sources of magnesium include unrefined (whole) grains, spinach, nuts, legumes, and white potatoes (tubers). This review presents recent research in the areas of magnesium and chronic disease, with the goal of emphasizing magnesium's role in disease prevention and overall health.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE

The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients.

METHODS

Twenty male chronic obstructive pulmonary disease patients (66.2 + 8.3 years old, FEV1: 49.3+19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion.

RESULTS

Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l).

CONCLUSIONS

The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Maternal-neonatal magnesium and zinc serum concentrations after vaginal delivery

BACKGROUND/AIMS

To investigate the effect of the mode of delivery on maternal-neonatal Mg and Zn levels.

MATERIAL AND METHODS

Two groups of pregnant women participated in the study: Group A (n = 16) with normal labor and vaginal delivery and group B (n = 14) with scheduled cesarean section (CS). Blood was obtained at the beginning of the labor, immediately after delivery and from the umbilical cord (CB). Serum Mg and Zn were measured with atomic absorption spectroscopy and total antioxidant status (TAS) levels with a chemical autoanalyser.

RESULTS

Mg, Zn and TAS levels were similar pre-delivery in both groups. TAS levels, Mg (0.81 ± 0.09 vs 0.69 ± 0.03 mmol/L, p < 0.001) and Zn levels (9.34 ± 0.37 vs 5.74 ± 0.24 μmol/L, p < 0.001) were significantly decreased after vaginal delivery. These biochemical parameters were measured practically unaltered at the same times of study in group B. The mineral levels did not differ in the CB of both groups.

CONCLUSIONS

The decreased maternal Mg, Zn and TAS levels post vaginal delivery may be due to the participation of skeletal and uterus muscles and the similar levels of the minerals in the CB of neonates to the placental protection.

Minerals as ergogenic aids

Chromium, magnesium, zinc, and selenium are essential minerals for humans. They all are involved in a number of metabolic reactions in the body; many of these reactions are involved in energy metabolism, and hence it is thought that they may exert an ergogenic effect. However, the data on their effects as ergogenic aids have been equivocal. Longitudinal research is required (including supplementation studies) to follow athletes over time and properly evaluate effects of these minerals upon performance. The purpose of this review is to evaluate the ergogenic effects of chromium, magnesium, zinc, and selenium.

Magnesium, the metabolic syndrome, insulin resistance, and type 2 diabetes mellitus

Magnesium is an essential mineral and has been established as a cofactor for over 300 metabolic reactions in the body. Some research has indicated that lower intakes of magnesium and lower serum magnesium concentrations may lead to and are associated with the metabolic syndrome, insulin resistance, and/or type 2 diabetes mellitus. The goal of this review is to examine the research conducted on: 1) magnesium status, metabolic syndrome, insulin resistance, and type 2 diabetes mellitus, and 2) the effects of magnesium intake and/or supplementation on metabolic syndrome, insulin resistance, and type 2 diabetes mellitus. To make this review as current as possible, the majority of research articles reviewed were from 2000 to the present.

Dietary supplements and sports performance: minerals

Minerals are essential for a wide variety of metabolic and physiologic processes in the human body. Some of the physiologic roles of minerals important to athletes are their involvement in: muscle contraction, normal hearth rhythm, nerve impulse conduction, oxygen transport, oxidative phosphorylation, enzyme activation, immune functions, antioxidant activity, bone health, and acid-base balance of the blood. The two major classes of minerals are the macrominerals and the trace elements. The scope of this article will focus on the ergogenic theory and the efficacy of such mineral supplementation.

Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism

This study examined whether supplementing the diet with a commercial supplement containing zinc magnesium aspartate (ZMA) during training affects zinc and magnesium status, anabolic and catabolic hormone profiles, and/or training adaptations. Forty-two resistance trained males (27 +/- 9 yrs; 178 +/- 8 cm, 85 +/- 15 kg, 18.6 +/- 6% body fat) were matched according to fat free mass and randomly assigned to ingest in a double blind manner either a dextrose placebo (P) or ZMA 30-60 minutes prior to going to sleep during 8-weeks of standardized resistance-training. Subjects completed testing sessions at 0, 4, and 8 weeks that included body composition assessment as determined by dual energy X-ray absorptiometry, 1-RM and muscular endurance tests on the bench and leg press, a Wingate anaerobic power test, and blood analysis to assess anabolic/catabolic status as well as markers of health. Data were analyzed using repeated measures ANOVA. Results indicated that ZMA supplementation non-significantly increased serum zinc levels by 11 - 17% (p = 0.12). However, no significant differences were observed between groups in anabolic or catabolic hormone status, body composition, 1-RM bench press and leg press, upper or lower body muscular endurance, or cycling anaerobic capacity. Results indicate that ZMA supplementation during training does not appear to enhance training adaptations in resistance trained populations.