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.     

Phosphate-loading tests influences on endurance-trained volunteers during restriction of muscular activity and chronic hyperhydration

The purpose of this investigation was to determine whether negative phosphate balance, which is developed during hypokinesia (a decreased number of walking steps/d) could be reversed with daily supplementation with phosphate, fluid, and salt (FSS). The studies on hypokinesia (HK) were performed for 364 d on 30 endurance-trained male volunteers in the age range of 23–26 yr, with an average maximum oxygen uptake, MOU, of 65 mL/kg min. All subjects were divided into three equal groups: Ten volunteers were placed on a continuous regime of exercise of 14.4 kmJd at 10,000 steps/d and served as controls. Ten volunteers were subject to continuous HK without FSS and were considered as the hypokinetic subjects (HS). The remaining subjects were under continuous HK and FSS and were considered as the hypokinetic, hyperhydrated subjects (HHS). The three groups were on a diet that averaged 2620 cal/d and contained 1.7 g calcium, 1.6 g phosphate, and 5.6 g sodium chloride. For simulation of the hypokinetic effect, the HS and HHS groups were kept continuously under 2.9 km/d (3000 walking steps/d) for the duration of the study. Prior to exposure to HK, all volunteers were on the same exercise regime as the controls. During a 60-d pre-HK period and during the remainder of the study, phosphate-loading tests, urinary and plasma phosphate concentrations were performed in all subjects. In the HHS group, plasma phosphate concentration and urinary excretion of phosphate were decreased, while in the HS group these values increased after phosphate loading. Based on our results, we concluded that chronic hyperhydration and phosphate supplementation may be used to minimize phosphate losses in endurance-trained volunteers during prolonged restriction of muscular activity.     

Fluid electrolyte changes in trained subjects after water loading and during restriction of muscular activity and chronic hyperhydration

The objective of this investigation was to determine fluid electrolyte changes after water-loading tests and during hypokinesia (decreased number of km taken per day) and daily intake of fluid and salt supplementation (FSS). The studies during hypokinesia (HK) were performed for 364 d on 30 endurance-trained male volunteers in the age range of 23–26 yr, with an average peak oxygen uptake, POU, of 64 mL/kg/min. All volunteers were divided into three equal groups: 10 volunteers were placed on a continuous regime of exercise of 14.4 km/d and served as control subjects (CS); 10 volunteers were submitted to continuous HK without FSS and were considered as the unsupplemented hypokinetic subjects (UHS); and 10 volunteers were under continuous HK and FSS and were considered as the supplemented hypokinetic subjects (SHS). For the simulation of the hypokinetic effect, the UHS and SHS groups were kept continuously under an average of 2.7 km/d for the duration of the study. Prior to exposure to HK, the two groups of volunteers were on the same exercise regime as the control group. During a 60-d preexperimental period and during the remainder of the study, water-loading tests with a water load of 20 mL/kg body wt/min were performed, and urinary and plasma electrolytes (sodium, potassium, calcium, and magnesium) were measured. In the SHS group, urinary excretion of electrolytes and plasma electrolyte content decreased, while in the UHS these values increased after water loading tests and during HK. Based on the obtained data, it is concluded that chronic hyperhydration may be used to prevent or minimize urinary and plasma electrolyte changes in endurance-trained volunteers after water-loading tests and during prolonged restriction of muscular activity.     

Potassium changes in trained subjects after potassium loading and during restriction of muscular activity and chronic hyperhydration

The objective of this investigation was to determine whether urinary and plasma potassium changes developed during prolonged hypokinesia (HK) (decreased number of km/d) in endurance-trained subjects could be minimized or reversed with a daily intake of fluid and salt supplementation (FSS). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr with an average peak oxygen uptake of 65 mL/kg min during 364 d of HK. All volunteers were on an average of 13.8 km/d prior to their exposure to HK. All volunteers were randomly divided into three groups: 10 volunteers were placed continuously under an average of 14.0 km/d (control subjects), 10 volunteers were subjected continuously to an average of 2.7 km/d (unsupplemented hypokinetic subjects), and 10 volunteers were submitted continuously to an average of 2.7 km/d, and consumed daily an additional amount of 0.1 g sodium chloride (NaCl)/kg body wt and 30 mL water/kg body wt (supplemented hypokinetic subjects). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d, potassium loading tests were performed with 1.5–1.7 mEq potassium chloride/kg body wt, and potassium, sodium, and chloride excretion in urine and potassium, sodium, and chloride in plasma were determined. In the unsupplemented hypokinetic volunteers, urinary excretion of electrolytes and concentrations of electrolytes in plasma increased significantly as compared to the control and supplemented hypokinetic groups of volunteers. It was concluded that daily intake of fluid and salt supplementation had a favorable effect on regulation of urinary and plasma potassium changes in trained subjects during prolonged HK.     

Urinary excretion of microelements in endurance-trained volunteers during restriction of muscular activity and chronic rehydration

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.     

Effect of daily hyperhydration on fluid-electrolyte changes in endurance-trained volunteers during prolonged restriction of muscular activity

The aim of this investigation was to evaluate the effect of a daily intake of fluid and salt supplementation on fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity (hypokinesia). The studies were performed on 30 long-distance runners aged 23–26 who had a peak oxygen uptake of 65.5 mL/kg/min and had taken 13.8 km/d on average prior to their participation in the study. The volunteers were divided into three groups: The volunteers in the first group were placed under normal ambulatory conditions (control subjects), the second group of volunteers subjected to hypokinesia alone (hypokinetic subjects), and the third group of volunteers was submitted to HK and consumed daily 0.1 g sodium chloride (NaCl)/kg body wt and 26 mL water/kg body wt (hyperhydrated subjects). The second and third group of volunteers were kept under an average of 2.7 km/d for 364 d. During the pre-experimental period of 60 d and during the experimental period of 364 d sodium, potassium, calcium, and magnesium in urine and plasma were determined. Blood was also assayed for osmolality, hemoglobin, hematocrit, plasma volume, plasma renin activity and plasma aldosterone. Mean arterial blood pressure was also determined. In the hyperhydrated volunteers plasma volume and arterial blood pressure increased, whereas plasma osmolality, plasma renin activity, plasma aldosterone, hematocrit, hemoglobin concentration, and urinary excretion and concentrations of electrolytes in plasma decreased. In the hypokinetic volunteers, plasma volume and arterial blood pressure decreased significantly, whereas hematocrit values, hemoglobin concenfration, plasma osmolality, plasma renin activity, plasma aldosterone, and electrolytes in urine and plasma increased significantly during the experimental period. It was concluded that chronic hyperhydration may be used in minimizing fluid and electrolyte losses in endurance-trained volunteers during prolonged restriction of muscular activity.     

Calcium loading and renal function in trained subjects during restriction of muscular activity and chronic hyperhydration

It was suggested that negative calcium balance is not based on the shortage of calcium in the diet, but on the decreased tissular capacity of the body to retain calcium during hypokinesia (decreased muscular activity), and that chronic hyperhydration may be used to normalize calcium balance. To evaluate this hypothesis studies were performed on 30 long distance runners aged 23–26 yr, with an average maximum oxygen uptake 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 14.9 km/d (control subjects), ten volunteers were subjected continuously to HK (hypokinetic subjects), and ten volunteers were submitted continuously to HK with daily consumption of an additional amount of 26 mL water/kg body wt and 0.16 g sodium chloride (NaCl)/kg body wt (hyperhydrated subjects). For the simulation of the hypokinetic effect, the hypokinetic and hyperhydrated volunteers were kept under an average of 2.7 km/day for 364 d. During the prehypokinetic period and hypokinetic period calcium lactate loading tests (0.55 mEq/kg body wt) were performed. Urinary and blood electrolytes (sodium, ionized calcium, total calcium, magnesium, and phosphate) and blood parathyroid hormone (PTH) were determined. Urinary electrolytes and concentrations in blood thereof decreased in the hyperhydrated and increased significantly in the hypokinetic volunteers. Blood parathyroid hormone content increased in the hyperhydrated and decreased in the hypokinetic volunteers. After calcium lactate loading tests, the hypokinetic volunteers displayed a faster excretion of calcium and a decreased blood PTH content as compared to the control and hyperhydrated groups of volunteers. It was concluded that calcium deficiency during HK is associated with decreased tissular capacity of the body to retain calcium, whereas chronic hyperhydration may be used to prevent calcium deficiency in endurance trained volunteers during prolonged restriction of muscular activity.     

Zinc metabolism in endurance-trained volunteers during prolonged restriction of muscular activity and chronic hyperhydration

The objective of this study was to evaluate the effects of hypokinesia (HK) and fluid- and salt supplementation (FSS) on zinc metabolism in endurance-trained volunteers (ETV) for a period of 364 d. Thirty long-distance runners aged 22–25 yr with a peak V_O2 of 67 mL/min/kg with an average 13.8 km/d running distance were chosen as subjects. They were equally divided into three groups:

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.     

Daily copper supplement effects on copper balance in trained subjects during prolonged restriction of muscular activity

The aim of this study was to assess the effect of a daily intake of copper supplements on negative copper balance during prolonged exposure to hypokinesia (decreased number of kilometers per day). During hypokinesia (HK), negative copper balance is shown by increased, not by decreased, serum copper concentration, as it happens in other situations. Studies were done during a 30-d prehypokinetic period and a 364-d hypokinetic period. Forty male trained volunteers aged 22–26 yr with a peak oxygen uptake of 66.4 mL/min/kg and with an average of 13.7 km/d running distance were chosen as subjects. They were equally divided into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SACS and SHKS groups took 0.09 mg copper carbonate/kg body weight daily. The SHKS and UHKS groups were maintained under an average running distance of 1.7 km/d, whereas the SACS and UACS groups did not experience any modifications in their normal training routines. During the 30-d prehypokinetic period and the 346-d hypokinetic period, urinary excretion of copper, calcium, and magnesium and serum concentrations of copper, calcium, and magnesium were measured. Copper loss in feces and copper balance was also determined. In both UHKS and SHKS groups, urinary excretion of copper, calcium, and magnesium and concentrations of copper, magnesium, and calcium in serum increased significantly when compared with the SACS and UACS groups. Loss of copper in feces was also increased significantly in the SHKS and UHKS groups when compared with the UACS and SACS groups. Throughout the study, the copper balance was negative in the SHKS and UHKS groups, whereas in the SACS and UACS groups, the copper balance was positive. It was concluded that a daily intake of copper supplements cannot be used to prevent copper deficiency shown by increased copper concentration. Copper supplements also failed to prevent negative copper balance and copper losses in feces and urine in endurancetrained subjects during prolonged exposure to HK.     

Water metabolic parameter changes in rhesus monkeys during exposure to prolonged restriction of motor activity

The objective of this investigation was to determine the effect of prolonged restriction of motor activity (hypokinesia [HK]) on several parameters of water metabolism in primates. The studies were performed on 12 rhesus monkeys aged 4–5 yr (5.10–6.85 kg) during the hypokinetic period of 90 d and during the prehypokinetic period of 30 d. They were divided into two equal groups: the first group was placed under ordinary vivarium conditions (vivarium control animals) and the second group was subjected to 90 d of HK (hypokinetic animals). For the simulation of the hypokinetic effect, the primates were immobilized on their abdomens in special tables. The legs of the monkeys were immobilized with hip and knee joints extended. The primates retained freedom of movement at elbow, wrist, and ankle. During the preexperimental period of 30 d and during the experimental period of 90 d, the following variables were determined: body weight, total body fluid content, specific total body fluid, mean fluid consumed and eliminated in urine, specific plasma resistance, hematocrit level, and plasma concentrations of sodium (Na) and potassium (K). In the hypokinetic primates, body weight decreased significantly when compared to the controls. Mean fluid intake, total body fluid, and specific total body fluid decreased, whereas mean daily fluid loss and specific mean daily fluid elimination increased significantly. Specific plasma resistance, hematocrit level, and plasma electrolyte concentrations increased significantly when compared to the control primates. It was concluded that prolonged restriction of motor activity induces significant changes in water metabolic parameters of primates leading in decreased total water content of the body.     

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:

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.     

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.     

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.     

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.     

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.     

Daily magnesium supplementation on serum and urinary magnesium changes in rats during prolonged restriction of motor activity

The objective of this investigation was to determine whether a plentiful magnesium (Mg²⁺) supplementation might be used to normalize or prevent Mg deficiency. This is manifested by increased rather than decreased serum Mg²⁺ concentration as is observed during prolonged hospitalization, which is developed during prolonged hypokinesia (HK) (decreased motor activity). Eighty male Wistar rats with an initial body weight of 370–390 g were used to perform the studies: They were equally divided into four groups:

1. Unsupplemented control animals (UCA);
2. Supplemented control animals (SCA);
3. Unsupplemented hypokinetic animals (UHA); and
4. Supplemented hypokinetic animals (SHA).

For the simulation of the hypokinetic effect, the hypokinetic animals were kept in small individual cages made of wood, which restricted their movements in all directions without hindering food and water intake. The control and hypokinetic supplemental animals receive 0.9 mg/mL Mg sulfate daily with their drinking water. Prior to and during the experimental period, urinary excretions of Mg, calcium, and phosphate along with their concentrations in serum, water intake, and urine excretion, and body weight were determined in the control and hypokinetic animals. In the supplemental and unsupplemental hypokinetic rats, urinary excretions and serum concentrations of electrolytes increased significantly, whereas serum concentration and urinary excretion thereof remained unchanged in the supplemented and unsupplemented control animals. It was concluded that a daily intake of large amounts of Mg supplementation cannot be used to prevent or normalize Mg deficiency in rats during prolonged exposure to HK.     

Muscle Calcium Metabolic Effects of Hypokinesia in Physically Healthy Subjects

The incompleteness of electrolyte deposition during hypokinesia (HK; diminished movement) is the defining factor of electrolyte metabolic changes, yet the effect of prolonged HK upon electrolyte deposition is poorly understood. The objective of this investigation was to determine the effect of muscle calcium (Ca⁺⁺) changes upon Ca⁺⁺ losses during prolonged HK. Studies were conducted on 20 physically healthy male volunteers during a pre-experimental period of 30 days and an experimental period of 364 days. Subjects were equally divided in two groups: control subjects (CS) and experimental subjects (ES). The CS group ran average distances of 9.2?±?1.2 km day^?l, and the ES group walked average distances of 2.3?±?0.2 km day^?l. Muscle Ca⁺⁺ contents, plasma Ca⁺⁺ concentrations, and Ca⁺⁺ losses in urine and feces were measured in the experimental and control groups of subjects. The muscle Ca⁺⁺ contents decreased (p?<?0.05), and plasma Ca⁺⁺ levels and Ca⁺⁺ losses in the urine and feces increased (p?<?0.05) in the ES group compared with their pre-experimental levels and the values in their respective CS group. Muscle Ca⁺⁺ contents and plasma Ca⁺⁺ levels and urinary and fecal Ca⁺⁺ losses did not change in the CS group compared to their pre-experimental levels. It is concluded that prolonged HK increase plasma Ca⁺⁺ concentrations and Ca⁺⁺ losses in Ca⁺⁺ deficient muscle indicating decreased Ca⁺⁺ deposition.