Measurements in potassium-supplemented athletes during and after hypokinetic and ambulatory conditions

Hypokinesia (diminished movement) induces significant potassium (K) changes; however, little is known about K deposition and deficiency during hypokinesia (HK). Using K supplements during and after HK, the aim was to establish body K deposition and K deficiency during HK. Studies were done during the pre-HK period of 30 d, HK period of 364 d, and post-HK period of 30 d. Forty male trained athletes aged 24.9 ± 8.0 y were chosen as subjects. They were equally divided into four groups: unsupplemented active control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented active control subjects (SACS), and supplemented hypokinetic subjects (SHKS). Hypokinetic subjects were limited to an average walking distance of 0.7 km/d. Control subjects ran an average distance of 11.6 km/d. The SHKS and SACS groups took 95.0 mg elemental K/kg body weight daily. Fecal K excretion, urinary sodium (Na) and K excretion, plasma K and Na levels, plasma renin activity (PRA), plasma aldosterone (PA), food and fluid intake, and physical characteristics were measured. During HK, fecal K loss, urinary K and Na loss, and plasma K, Na, PRA, and PA levels increased significantly (p ≤ 0.05), whereas during the initial days of post-HK, the levels of the measured parameters decreased significantly (p ≤ 0.05) in the SHKS and UHKS groups as compared with the SACS and UACS groups, respectively. During HK, body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p ≤ 0.05), whereas during the initial days of post-HK period remained significantly (p ≤ 0.05) depressed and fluid intake increased in SHKS and UHKS groups when compared with the SACS and UACS groups, respectively. However, during HK and post-HK plasma, urinary, and fecal K changed significantly (p ≤ 0.05) more in the SHKS group than in the UHKS group. The deposition of K was significantly (p ≤ 0.05) lower and K deficiency much higher in the SHKS group than in the UHKS group. Fecal K loss, urinary K and Na loss, plasma K, Na, PRA, and PA levels, body weight, body fat, peak oxygen uptake, and food and fluid intake did not change significantly in the SACS and UACS when compared with their baseline control values. It was shown that plasma K concentration and urinary and fecal K excretion increased during HK and decreased significantly (p ≤ 0.05) during post-HK. post-HK. Oral K supplements did not influence plasma or fecal and urinary K either during HK or post-HK. It was concluded that the low plasma K level and fecal and urinary K loss during post-HK may indicate the presence of K deficiency, and increased K in plasma, urine, and feces during HK and in the presence of K deficiency may suggest the body’s inability to retain K during HK.     

Calcium supplementation effect on calcium balance in endurance-trained athletes during prolonged hypokinesia and ambulatory conditions

Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of a HK period. Forty male athletes aged 23–26 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average running distance of 0.7 km/d. In the SHKS and SACS groups supplemented with 35.0 mg Ca lactate/kg body weight. Fecal Ca loss, urinary excretion of Ca and phosphate (P), serum concentrations of ionized calcium (Ca_I) total Ca, P, and Ca balance, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D (1,25(OH)2D), anthropometric characteristics and peak oxygen uptake were measured. Fecal Ca excretion, urinary Ca and P excretion, serum Ca_I, total Ca, and P concentration, and negative Ca balanced increased significantly (p ≤ 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. Serum, urinary, and fecal Ca changes were much greater and appeared much faster in the SHKS group than in the UHKS group. Serum iPTH and 1,25 (OH)2 D, body weight, and peak oxygen uptake decreased significantly (p ≤ 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. In contrast, the corresponding parameters remained stable in the SACS and UACS groups when compared with the baseline control values. It was concluded that during prolonged HK, urinary and fecal Ca excretion and serum Ca concentration increased significantly despite the presence of a negative Ca balance; thus, Ca supplements cannot be used to normalize negative Ca balance during prolonged HK.     

Serum, urinary, and fecal calcium changes in trained and untrained subjects during prolonged hypokinetic and ambulatory conditions

Electrolyte metabolism undergoes significant changes in trained subjects, but it is unknown if it undergoes significant changes in untrained subjects during hypokinesia (decreased movement). The aim of this study was to measure calcium (Ca) changes in trained and untrained subjects during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and 364 d of a HK period. Forty male trained and untrained volunteers aged 23–26 yr were chosen as subjects. All subjects were equally divided into four groups: trained ambulatory control subjects (TACS), trained hypokinetic subjects (THKS), untrained hypokinetic subjects (UHKS), and untrained ambulatory control subjects (UACS). The THKS and UHKS groups were kept under an average running distance of 0.7 km/d. Fecal Ca excretion, urinary Ca and magnesium (Mg) excretion, serum ionized calcium (Ca_I), Ca, Mg, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D [1,25 (OH)2 D] concentration, body weight, and peak oxygen uptake were measured. Fecal Ca loss, urinary Ca and Mg excretion, and serum Ca_I, Mg, and Ca increased significantly (p ≤ 0.01), whereas serum iPTH and 1,25 (OH)2 D concentration body weight and peak oxygen uptake decreased significantly (p ≤ 0.01) in the THKS and UHKS groups when compared with the TACS and UACS groups. The measured parameters were much greater and much faster in the THKS group than in the UHKS group. By contrast, the corresponding parameters did not change significantly in the TACS and UACS groups when compared with the baseline control values. It was concluded that prolonged HK induces significant fecal, urinary, and serum Ca changes in the hypokinetic subjects when compared with control subjects. However, fecal, urinary, and serum Ca changes were much greater and appeared much faster in the THKS group than the UHKS group.     

Phosphate deposition capacity of athletes during hypokinesia, phosphate loading, and ambulation

Hypokinesia (diminished movement) induces significant phosphate (P) excretion; however, little is known about the P deposition ability of the body during hypokinesia (HK). Using P loads, the aim of this study was to establish the deposition ability of the body to retain P during prolonged HK. Studies were done during a 30-d period of pre-HK and a 364-d period of HK. Forty male trained athletes aged 24.7 ± 8.0 yr were chosen as subjects. They were equally divided into four groups: unloaded ambulatory control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded ambulatory control subjects (LACS), and loaded hypokinetic subjects (LHKS). All hypokinetic subjects were limited to an average walking distance of 0.7 km/d. Loading tests with 85.0 mg of calcium phosphate/kg body weight were performed on the LACS and LHKS. Fecal P loss, urinary calcium (Ca) and P loss, serum P, Ca, and the ionized calcium (Ca_I) levels increased significantly (p≤0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. Serum intact parathyroid hormone (iPTH) and the 1,25-dihydroxyvitamin D₃ [1,25-(OH)₂ D₃] levels decreased significantly (p≤0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. After the P load, significant (p≤0.05) differences were observed between LHKS and UHKS groups regarding serum, urinary, and fecal P changes. Thus, the deposition capacity of P decreased significantly (p≤0.05) more in the LHKS group than in the UHKS group. The deposition of P, fecal P, urinary P and Ca, serum Ca_I, P, Ca, 1,25-(OH)₂ D₃, and iPTH changed insignificantly (p>0.05) in control groups when compared with their baseline values. It was shown that after the P load, significant differences were observed between the loaded and unloaded hypokinetic subjects regarding serum, urinary, and fecal P values and P retention. The oral P load intensified P loss from the body. It was concluded that the higher the P intake increased the greater P loss and the lower P deposition and thus the less likely it is for the P load to benefit hypokinetic subjects.     

Muscle electrolyte measurements during and after hypokinesia in determining muscle electrolyte depletion during hypokinesia in the rat

Hypokinesia (diminished movement) induces muscle mineral depletion. However, the mechanism of muscle mineral depletion during hypokinesia (HK) remains unknown. Measuring electrolyte retention and electrolyte values in muscle, plasma, and urine during and after HK, the aim of this study was to discover if HK could depress mineral retention and lead to muscle mineral depletion. Studies were done on 204 13-wk-old male Wistar rats (370–390 g) during 10 d pre-HK period, 98 d HK period, and 15 d post-HK period. Rats were equally divided into two groups: vivarium control rats (VCR) and hypokinetic rats (HKR). All hypokinetic rats were kept for 98 d in small individual cages, which restricted their movements in all directions without hindering food and water intakes. All control rats were housed for 98 d in individual cages under vivarium control conditions. Both groups of rats were pair-fed. During the HK period skeletal muscle sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and water content and electrolyte retention decreased significantly (p < 0.05), while urinary and plasma electrolyte levels increased significantly (p < 0.05) in HKR compared with their pre-HK values and their respective VCR. During the initial days of the post-HK period, mineral retention increased significantly (p < 0.05), plasma and urinary electrolyte level decreased significantly (p < 0.05), while muscle electrolyte and water content remained significantly (p < 0.05) depressed in HKR compared with VCR. Muscle mineral and water content, electrolyte retention, plasma, and urinary electrolyte values did not change in VCR compared with their pre-HK values. It was concluded that during HK decreased muscle mineral content may suggest muscle mineral depletion, while increased urinary electrolyte loss and muscle mineral depletion may demonstrate reduced mineral retention. Reduced electrolyte excretion and depressed muscle mineral content during post-HK may indicate skeletal muscle mineral depletion during HK. Dissociation between electrolyte retention and muscle mineral depletion may demonstrate the presence of decreased electrolyte retention as the mechanism of muscle electrolyte depletion during prolonged HK.     

Magnesium deposition and depletion in magnesium supplemented rats during and after hypokinesia and vivarium control

Hypokinesia (diminished movement) induces significant magnesium (Mg) changes; however, little is known about Mg deposition and Mg depletion during HK. Measuring the Mg level in some tissues during HK and post-HK and Mg supplement, we aimed to establish Mg deposition and Mg depletion during prolonged HK. Studies were done on 408, 13-wk-old male Wistar rats (370-390 g) for a 15-d pre-HK period, a 98-d HK period, and a 15-d post-HK period. Rats were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR), and supplemented hypokinetic rats (SHKR). Both UHKR and SHKR were kept in small individual cages. The SVCR and SHKR took 53 mg Mg/d. During the HK period, plasma, urinary, and fecal Mg levels increased significantly (p < or = 0.05), whereas during the post-HK period Mg deposition, muscle and bone Mg content decreased significantly (p < or = 0.05) in UHKR and SHKR when compared with their pre-HK values and their respective vivarium controls (UVCR and SVCR). During the initial days of the post-HK period, plasma, urinary, and fecal Mg levels decreased significantly (p < or = 0.05), whereas during the post-HK period Mg deposition, muscle and bone Mg content remained significantly (p < or = 0.05) depressed in UHKR and SHKR when compared with UVCR and SVCR, respectively. However, during the HK period and post-HK period Mg deposition, bone, muscle, plasma, urinary, and fecal Mg levels changed significantly (p < or = 0.05) more in SHKR than UHKR. By contrast, during the HK period and post-HK period. Mg deposition, muscle, bone, plasma, urinary, and fecal Mg values change insignificantly (p > 0.05) in UVCR and SVCR when compared with their pre-HK values. It was concluded that reduced muscle, bone, plasma, urinary, and fecal Mg during post-HK and Mg supplement may demonstrate Mg depletion, whereas higher Mg loss during HK despite reduced muscle and bone Mg and Mg depletion might demonstrate Mg deposition incapacity during HK.     

Phosphate deposition during and after hypokinesia in phosphate supplemented and unsupplemented rats

The objective of this study was to show that prolonged restriction of motor activity (hypokinesia) could reduce phosphate (P) deposition and contribute to P loss with tissue P depletion. To this end, measurements were made of tissue P content, P absorption, plasma P levels, urinary and fecal P excretion of rats during and after hypokinesia (HK) and daily phosphate supplementation. Studies were conducted on male Wistar rats during a pre-hypokinetic period, a hypokinetic period and a post-hypokinetic period. All rats were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR) and supplemented hypokinetic rats (SHKR). Bone and muscle P content, plasma intact parathyroid hormone (iPTH) levels, P absorption, plasma P levels and urinary and fecal P excretion did not change in SVCR and UVCR compared with their pre-HK values. During HK, plasma P levels, urinary and fecal P excretion increased significantly (p<0.05) while muscle and bone P content, P absorption and plasma iPTH levels decreased significantly (p<0.05) in SHKR and UHKR compared with their pre-HK values and the values in their respective vivarium controls (SVCR and UVCR). During the initial 9-days of post-HK, plasma, urinary and fecal P levels decreased significantly (p<0.05), and plasma iPTH levels, muscle and bone P levels remained significantly (p<0.05) depressed in hypokinetic rats compared with their pre-HK values and the values in their respective vivarium control rats. By the 15th day, these values approached the control values. During HK and post-HK, changes in P absorption, plasma iPTH levels, and P levels in muscle, bone, plasma, urine and feces were significantly (p<0.05) greater in SHKR than in UHKR. Decreased tissue P content with increased P loss in animals receiving and not receiving P supplementation demonstrates decreased P deposition during HK. Higher P excretion with lower tissue content in SHKR and UHKR demonstrates that P deposition is decreased more with P supplementation than without. Because SHKR with a lower tissue P content showed higher P excretion than UHKR it was concluded that the risk of decreased P deposition with greater tissue P depletion is inversely related to P intake, that is, the higher the P intake the greater the risk for decreased P deposition and the greater tissue P depletion. It was shown that P (regardless of the intensity of its tissue depletion) is lost during HK unless factors contributing to the decreased P deposition are partially or totally reversed. It was concluded that dissociation between (decreased) tissue P content and (increased) P uptake indicates decreased P (absorption and) deposition as the main mechanisms of tissue P depletion during prolonged HK.     

Urinary and serum electrolyte changes in athletes during periodic and continuous hypokinetic and ambulatory conditions

Hypokinesia (HK) (diminished movement) induces significant electrolyte changes, but little is known about the effect of periodic hypokinesia (PHK) on minerals. The aim of this study was to measure the effect of PHK and continuous hypokinesia (CHK) on urinary and serum electrolytes. Studies were done during a 30-d period of prehypokinesia (HK) and during 364 d of PHK and CHK periods. Thirty male athletes aged 24.6±7.7 yr were chosen as subjects. They were equally divided into three groups: unrestricted ambulatory control subjects (UACS), continuously hypokinetic subjects (CHKS), and periodically hypokinetic subjects (PHKS). The UACS group experienced no changes in the daily activities and regular training and they were maintained under an average running distance of 11.7 km/d. The CHKS group was limited to an average walking distance of 0.7 km/d; and the PHKS group was limited to an average walking distance of 0.7 and running distance of 11.7 km/d for 5 d and 2 d/wk, respectively, for a period of 364 d. Urinary and serum phosphate (P), calcium (Ca), sodium (Na) and potassium (K), serum intact parathyroid hormone (iPTH), calcitonin (CT), plasma renin activity (PRA) and aldosterone (PA) levels, food and water intakes, and physical characteristics were measured. Urinary P, Ca, Na, and K loss, serum Ca, P, Na, and K, and PRA and PA values increased significantly (p≤0.01), whereas serum iPTH and CT levels decreased significantly (p≤0.01) in the PHKS and CHKS groups when compared with the UACS group. However, significant (p≤0.01) differences were observed between PHKS and CHKS groups regarding urinary and serum electrolytes, serum and plasma hormones. Food and water intakes, body weight, body fat, and peak oxygen uptake decreased significantly (p ≤ 0.01) in the CHKS group when compared with PHKS and UACS groups. Food and fluid intakes, body fat, and body weight increased significantly (p≤0.01), whereas peak oxygen uptake remained significantly (p≤0.01) higher in the PHKS group when compared with the CHKS group. Serum and urinary minerals, serum hormones, food and fluid intakes, and physical characteristics did not change significantly (p>0.01) in the UACS group when compared with their baseline control values. It was shown that both PHK and CHK induce significant serum and urinary electrolyte changes. However, urinary and serum electrolyte changes were significantly (p≤0.01) greater during PHK than CHK. It was concluded that the greater the stability of muscular activity, the smaller the serum and urinary electrolyte changes during prolonged HK.     

Phosphate determination during hypokinesia and ambulation in establishing phosphate changes in trained and untrained subjects

Hypokinesia (diminished movement) induces phosphate (P) changes; however, it is not known if P change is greater in trained than untrained subjects. Measuring P balance and P retention during hypokinesia (HK) and P load, we studied if changes in P retention and P depletion were significantly (p<0.05) greater in trained than untrained subjects. Studies were done during a 30-d pre-HK period and a 364-d HK period. Forty male trained and untrained healthy individuals aged 24.5±5.4 yr were chosen as subjects. All volunteers were equally divided into four groups: trained ambulatory control subjects (TACS), trained hypokinetic subjects (THKS), untrained ambulatory control subjects (UACS), and untrained hypokinetic subjects (UHKS). All THKS and UHKS were limited to an average walking distance of 0.3 km/d, and TACS and UACS were on an average running distance of 9.8 and 1.8 km/d, respectively. Subjects took daily 12.7-mmol dicalcium-phosphate/kg body weight in the form of supplementation. Negative P balance, fecal P loss, urinary P and calcium (Ca) excretion, serum P, and total Ca (Ca_t) levels increased significantly (p<0.05), whereas P retention, serum 1,25-dihydroxyvitamin D [1,25 (OH)₂D₃] and intact parathyroid hormone (iPTH) level decreased significantly (p<0.05) in THKS and UHKS when compared with their pre-HK values and their respective ambulatory controls (TACS and UACS). However, P retention, P balance, serum, urinary, and fecal P, and serum hormone level changed significantly (p<0.05) more in THKS than UHKS. Retention of P, fecal P, urinary P and Ca loss, serum P and Ca_t level, P balance, 1,25(OH)₂D₃, and iPTH level change insignificantly (p>0.05) in TACS and UACS when compared with their pre-HK control values. It was concluded that significant negative P balance may indicate P depletion, whereas significant P loss in spite of negative P balance and P load may suggest P retention incapacity; however, P depletion was greater in THKS than UHKS. Clearly, P is wasted much more in THKS than UHKS.     

Potassium loading effect on potassium balance in athletes during prolonged restriction of muscular activity

Negative potassium balance during hypokinesia (decreased number of kilometers taken/day) is not based on the potassium shortage in the diet, but on the impossibility of the body to retain potassium. To assess this hypothesis, we study the effect of potassium loading on athletes during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 23–26 yr were chosen as subjects. They were divided equally into four groups: unloaded ambulatory control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded hypokinetic subjects (LHKS), and loaded ambulatory control subjects (LACS). For the simulation of the hypokinetic effect, the LHKS and UHKS groups were kept under an average running distance of 1.7 km/d. In the LACS and LHKS groups, potassium loading tests were done by administering 95.35 mg KC1 per kg body weight. During the pre-HK and HK periods and after KC1 loading tests, fecal and urinary potassium excretion, sodium and chloride excretion, plasma potassium, sodium and chloride concentration, and potassium balance were measured. Plasma renin activity (PRA) and plasma aldosterone concentration was also measured. Negative potassium balance increased significantly (p < -0.01) in the UHKS and LHKS groups when compared with the UACS and LACS groups. Plasma electrolyte concentration, urinary electrolyte excretion, fecal potassium excretion, PRA, and PA concentration increased significantly (p ≤ 0.01) in the LHKS and UHKS groups when compared with LACS and UACS groups. Urinary and fecal potassium excretion increased much more and much faster in the LHKS group than in the UHKS group. By contrast, the corresponding parameters change insignificantly in the UACS and LACS groups when compared with the base line control values. It was concluded that urinary and fecal potassium excretion increased significantly despite the presence of negative potassium balance; thus, negative potassium balance may not be based on potassium shortage in the diet because of the impossibility of the body to retain potassium during HK.     

Magnesium loading effect on magnesium deficiency in endurance-trained subjects during prolonged restriction of muscular activity

The aim of this study was to evaluate the effect of magnesium (Mg) loading (10.0 mg Mg/kg body wt) and daily Mg supplements (5.0 mg Mg/kg body wt) on Mg deficiency shown by increased and not by decreased serum Mg concentration during hypokinesia (decreased km number/d). The studies were done during 30 d of prehypokinesia and 364 d of hypokinesia (HK) periods. Forty endurance-trained volunteers aged 22–26 yr with a peak VO2 max of 66.3 mL·kg⁻¹ min⁻¹ and with an average 15.0 km/d running distance were chose as subjects. They were equally divided into four groups:

Blood plasma concentrations of microelements in endurance trained volunteers during hypokinesia and chronic hyperhydration

The objective of this investigation was to determine the effect of daily intake of fluid and salt supplementation (FSS) on increased urinary losses of microelements that developed during hypokinesia (decreased number of walking steps/d). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr, with an averaged maximum oxygen uptake of 65 mL/kg/min during 364 d of hypokinesia (HK). All volunteers were divided into three equal groups: Ten volunteers were placed continuously under an average of 10,000 running steps/d (14.2 km/d) (control subjects), ten volunteers subjected continuously to HK without the use of FSS (hypokinetic subjects), and ten volunteers were continuously submitted to HK and consumed daily FSS (hyperhydrated subjects). For the simulation of the hypokinetic effect the hypokinetic and hyperhydrated volunteers were kept under an average of 3,000 walking steps/d (2.7 km/d) for 364 d. Prior to their exposure to HK the volunteers were on an average of 10,000 running steps/d (14.2 km/d). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d were determined renal excretion of microelements responses of endurance-trained volunteers. In the hyperhydrated volunteers urinary excretion of iron, zinc, copper, manganese, cobalt, nickel, lead, tin, chromium, aluminum, molybdenum, and vanadium decreased, whereas in the hypokinetic volunteers it increased significantly. It was concluded that chronic hyperhydration may be used to attenuate urinary excretion of microelements in endurance-trained volunteers during prolonged restriction of muscular activity.     

Blood cell lead, calcium, and magnesium levels associated with pregnancy-induced hypertension and preeclampsia

This study compares the red blood cell (Rbc) levels of lead (Pb), calcium (Ca), and magnesium (Mg) in relation to blood pressure in 39 pregnant women in the third trimester of pregnancy. The study population included 20 women with normal pregnancies, 15 with mild hypertension, and 4 with severe hypertension and preeclampsia. The mean±SD for each group was calculated and the difference between the means of the normotensive and the other groups were compared by analysis of variance. Significant differences from normal to the preeclamptic pregnancies were in (1) elevated Rbc Pb (p≤0.001), (2) lower Rbc Ca (p≤0.001), and (3) lower Rbc Mg/Pb ratio (p≤0.0001). Pearson’s rank correlation between blood pressure showed a direct relation to the Rbc Pb level (p≤0.01) and an inverse relation to the Rbc Ca and Mg/Pb ratio (p≤0.004,≤0.007). Apparently, prenatal blood pressure is directly proportional to Rbc Pb content and related or modified by Rbc Ca and Mg.     

Tissue magnesium loss during prolonged hypokinesia in magnesium supplemented and unsupplemented rats

This study aims at showing that during hypokinesia (HK) tissue magnesium (Mg2+) content decreases more with higher Mg2+ intake than with lower Mg2+ intake and that Mg2+ loss increases more with higher than lower tissue Mg2+ depletion due to inability of the body to use Mg2+ during HK. Studies were conducted on male Wistar rats during a pre-HK period and a HK period. Rats were equally divided into four groups: unsupplemented vivarium control rats (UVCR), unsupplemented hypokinetic rats (UHKR), supplemented vivarium control rats (SVCR) and supplemented hypokinetic rats (SHKR). SVCR and SHKR consumed 42 mEq Mg2+ per day. The gastrocnemius muscle and right femur bone Mg2+ content decreased significantly, while plasma Mg2+ level and urine and fecal Mg2+ loss increased significantly in SHKR and UHKR compared with their pre-HK values and their respective vivarium controls (SVCR and UVCR). However, muscle and bone Mg2+ content decreased more significantly and plasma Mg2+ level, and urine and fecal Mg2+ loss increased more significantly in SHKR than in UHKR. The greater tissue Mg2+ loss with higher Mg2+ intake and the lower tissue Mg2+ loss with lower Mg2+ intake shows that the risk of higher tissue Mg2+ depletion is directly related to the magnitude of Mg2+ intake. The higher Mg2+ loss with higher tissue Mg2+ depletion and the lower Mg2+ loss with lower Mg2+ tissue depletion shows that the risk of greater Mg2+ loss is directly related to the magnitude of tissue Mg2+ depletion. It was concluded that tissue Mg2+ depletion increases more when the Mg2+ intake is higher and that Mg2+ loss increases more with higher than lower tissue Mg2+ depletion indicating that during prolonged HK the tissue Mg2+ depletion is not due to the Mg2+ shortage in food but to the inability of the body to use Mg2+.     

Potassium supplements’ effect on potassium balance in athletes during prolonged hypokinetic and ambulatory conditions

Electrolyte supplements may be used to prevent changes in electrolyte balance during hypokinesia (diminished movement). The aim of this study was to measure the effect of potassium (K) supplements on K balance during prolonged hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 25.1±4.4 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS) and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average walking distance of 0.7 km/d. The SACS and SHKS groups were supplemented daily with 50.0 mg elemental potassium chloride (KCl) per kilogram body weight. The K balance, fecal K excretion, urinary K, sodium (Na), and chloride (Cl) excretion, plasma K, Na, and Cl concentration, plasma renin activity (PRA) and plasma aldosterone (PA) concentration, anthropometric characteristics and peak oxygen uptake were measured. Negative K balance, fecal K excretion, urinary K, Na, and Cl excretion, plasma K, Na, and Cl concentration, and PRA and PA concentration increased significantly (p≤0.01), whereas body weight and peak oxygen uptake decreased significantly in the SHKS and UHKS groups when compared with SACS and UACS groups. However, the measured parameters changed much faster and much more in SHKS group than UHKS group. By contrast, K balance, fecal, urinary, and plasma K, plasma hormones, body weight, and peak oxygen uptake did not change significantly in the SACS and UACS groups when compared with the baseline control values. It was concluded that prolonged HK induces a significant negative K balance associated with increased plasma K concentration and urinary and fecal K excretion. However, negative K balance appeared much faster and was much greater in the SHKS group than UHKS group. Thus, K supplementation was not effective in preventing negative K balance during prolonged HK.     

Daily hyperhydration effect on electrolyte deficiency of endurance-Trained subjects during prolonged hypokinesia

The aim of this study was to evaluate the effect of a daily intake of fluid and salt supplementation (FSS) on the deficiency of electrolytes, which is characterized by higher rather than lower plasma concentration of electrolytes during prolonged hypokinesia (HK) (decreased number of km taken per day). Forty long distance runners aged 22–25 yr with a peak V0₂ 65.4 mL min^-1 kg^-1 with an average 14.2 km d running distance were selected as subjects. They were equally divided into four groups: 1) unsupplemented control subjects (UCS); 2) unsupplemented hypokinetic subjects (UHS); 3) supplemented hypokinetic subjects (SHS), and 4) supplemented control subjects (SCS). During the investigation of 364 d, groups 2 and 3 maintained an average running distance of less than 4.7 km per day, groups 1 and 4 did not experience any modification in their normal training routines and diets. During the preexperimental period of 60 d and during the experimental period of 364 d urinary excretion of electrolytes and concentrations of sodium, potassium, calcium, and magnesium in plasma were determined. Whole blood hemoglobin, hematocrit index, plasma osmolality, and plasma protein concentration were measured. In the UHS plasma concentration of electrolytes and urinary excretion thereof, fluid elimination, hematocrit, whole blood hemoglobin, plasma osmolality, and plasma protein concentration increased significantly (p < 0.05) when compared with the UCS, SCS, and SHS groups. In the SHS plasma concentration of electrolytes and urinary excretion thereof, fluid excretion, whole blood hemoglobin, hematocrit, plasma osmolality, and plasma protein concentration decreased when compared with the UHS and increased insignificantly when compared with the UCS and SCS groups. It was concluded that FSS may be used to prevent or minimize electrolyte deficiency in endurance-trained volunteers during prolonged restriction of muscular activity.     

Relationship Between Serum Calcium and Magnesium Concentrations and Metabolic Syndrome Diagnostic Components in Middle-Aged Korean Men

It is thought that calcium and magnesium may be related to metabolic disorders such as obesity and metabolic syndrome; however, to date, there have been few studies investigating the association between serum calcium and magnesium levels and metabolic syndrome in middle-aged male adults. We aimed to investigate the association between serum calcium and magnesium levels and metabolic syndrome in Korean middle-aged male adults. Study subjects included 213 men aged 30∼60 years. MetS risk score is determined by adding the number of risk factors, waist circumference, triacylglyceride (TG), HDL cholesterol, glucose, and blood pressure (BP). The study population was divided into three groups according to the MetS risk score: group I (MetS risk score ≤1; n = 106), group II (MetS risk score = 2; n = 51), and group III (MetS risk score ≥3; n = 56). The serum Ca, according to increase of MetS risk score, was significantly higher (p < 0.001), and there was no significant difference in serum Mg concentration among the three groups. Subjects with high TG and high BP had higher serum calcium levels than those without such abnormalities. Subjects with higher glucose had lower serum magnesium levels than those without such abnormality. The correlation analysis indicated that the serum Ca had positive correlations with the MetS risk score (r = 0.1769, p < 0.01), serum TG (r = 0.2516, p < 0.001), and DBP (r = 0.2246, p < 0.01). The correlation analysis indicated that the serum Mg had an inverse relationship with serum glucose (r = −0.2404, p < 0.001). In conclusion, serum Ca had positive association with TG and BP, while serum Mg had negative association with serum glucose after adjusting age and BMI among the middle-aged Korean male adults.     

Electrolyte changes in plasma and urine of athletes during acute and rigorous bed rest and ambulatory conditions

Rigorous bed rest (RBR) induces significant electrolyte changes, but little it is not known about the effect of acute bed rest (ABR) (i.e., abrupt confinement to a RBR). The aim of this study was to measure urinary and plasma electrolyte changes during ABR and RBR conditions. The studies were done during 3 d of a pre-bed-rest (BR) period and during 7 d of an ABR and RBR period. Thirty male trained athletes aged, 24.4 ± 6.6 yr were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), acute-bed-rested subjects (ABRS), and rigorous-bed-rested subjects (RBRS). The UACS group experienced no changes in professional training and daily activities. The ABRS were submitted abruptly to a RBR regimen and without having any prior knowledge of the exact date and time when they would be subjected to an RBR regimen. The RBRS were subjected to an RBR regime on a predetermined date and time known to them from the beginning of the study. Sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and phosphate (P) in plasma and urine, plasma renin activity (PRA) and plasma aldosterone (PA), physical characteristics, peak oxygen uptake, and food and water intakes were measured. Urinary Na, K, Ca, Mg, and P excretion and plasma Na, K, Mg, Ca, and P concentration, PRA, and PA concentration increased significantly (p ≤ 0.01), whereas body weight, peak oxygen uptake, and food and water intakes decreased significantly in the ABRS and RBRS groups when compared with the UACS group. However, urinary and plasma Na, K, Mg, P, and Ca, PRA, and PA values increased much faster and were much greater in the ABRS group than in the RBRS group. Plasma and urinary Na, K, Ca, Mg, and P, PRA and PA levels, food and water intakes, body weight, and peak oxygen uptake did not change significantly in the UACS group when compared with its baseline control values. It was shown that RBR and ABR conditions induce significant increases in urinary and plasma electrolytes; however, urinary and plasma electrolyte changes appeared much faster and were much greater in the ABRS group than the RBRS group. It was concluded that the more abruptly motor activity is ended, the faster and the greater the urinary and plasma electrolyte change.     

A study of some serum mineral levels before and during pregnancy and during lactation period of sheep and cattle

The purpose of this study was to determine serum Cu, Zn, Mn, K, and Mg levels before and during pregnancy and during the lactation period of sheep and cattle and to determine the relationships between periods. For this purpose, blood samples of 14 healthy, pregnant Brown Swiss cows fed under normal condition and 36 Karakaş (İvesi × Akkaraman) sheep were used. Blood samples were analyzed using an atomic absorption spectrophotometer. There were significant differences between before pregnancy and during pregnancy, and during pregnancy and the lactation period for serum Zn concentration; also before pregnancy and during pregnancy, and before pregnancy and the lactation period for serum K concentration in cows (p<0.05). There were significant differences between before pregnancy and the lactation period for serum Cu concentration, and before pregnancy and during pregnancy for serum K concentration; also pregnancy and the lactation period for serum Mg concentration in sheep (p<0.05).     

Associations of Serum Ca and Mg Levels with Mental Health in Adult Women Without Psychiatric Disorders

Several lines of evidence from previous studies suggest that Calcium (Ca) and Magnesium (Mg) may be involved in intracellular and interneuronal processes associated with affective disorders. However, there have been inconsistent results on the effect of Ca and Mg on depressive mood disorder. This cross-sectional study was conducted to determine whether serum Ca and Mg levels, as well as serum Ca/Mg ratio, are associated with mental health in relatively healthy, adult women without psychiatric disorders. One hundred and twelve adult women were recruited from the outpatient clinic in a university hospital setting. Serum Ca and Mg levels were measured and indicators of mental health such as depression, anxiety, and stress were evaluated using two validated questionnaires; the Hospital Anxiety Depression Scale and the Modified Brief Encounter Psychosocial Instrument Stress Scale. After categorizing the serum Ca and Mg levels, and the Ca/Mg ratio into tertiles, the mean scores on each mental health scale were compared using analysis of covariance. The risk of depressive mood disorder according to the tertiles of serum Mg level and serum Ca/Mg ratio was assessed using logistic regression analysis. Women in the middle tertile of serum Ca/Mg ratio had significantly lower scores on depression and stress scales (p = 0.004 and p = 0.007, respectively) and a lower odds ratio (OR) for the risk of depressive mood disorder (OR = 0.31, CI_95% 0.10–0.93) than those in the highest tertile. The OR for the risk of depressive mood disorder was higher in women in the lowest tertile of serum Mg than in those in the highest tertile (OR = 3.92, CI_95% 1.11–13.83). Serum Mg level and serum Ca/Mg ratio may be involved in the mechanism for the progression of depressive mood or stress perception in relatively healthy, adult women.