The effects of smoking on the health and sleep of sportswomen.

This survey studied the health and sleeping patterns of 92 physical education and sports science students highly involved in sport. A strong correlation was found between smoking and various complaints of ill health as well as between smoking and sleep duration and quality of sleep. The results suggest that there is a strong relationship between the constituents of tobacco smoke and poor sleeping habits.     

Cumulative effects of calcium supplementation and physical activity on bone accretion in premenarchal children: a double-blind randomised placebo-controlled trial

High calcium intake combined with physical activity during childhood have been shown to improve bone mass accrual and bone mineral density. Our aim was to study the combined effect of calcium and exercise on bone gain in children. Two milk-powder products containing either 800 mg of calcium phosphate (calcium) or not (placebo) were randomly allocated to 113 healthy premenarchal girls on a daily basis for 1 year. The group was composed of 63 exercise (7.2 +/- 4 hours of exercise/week) and 50 sedentary (1.2 +/- 0.8 hours of exercise/week) children. The final experiment had 4 groups: exercise/calcium (n = 12), exercise/placebo (n = 42), sedentary/calcium (n = 10), and sedentary/placebo (n = 21). Bone mineral density (BMD) at 6 skeletal sites and body composition were determined by DXA. Bone age was calculated and the daily spontaneous calcium intake was assessed by a frequency questionnaire. All the tests were performed at baseline and 1 year by the same observer. BMD gains were significantly greater in the exercise/calcium group than in other groups at the total body (increase of 6.3 %, p < 0.05), lumbar spine (11 %, p < 0.05), femoral neck (8.2 %, p < 0.02), and Ward's triangle (9.3 %, p < 0.01). There was no difference between the other groups. These data suggest that calcium supplementation increases the effect of physical exercise on bone mineral acquisition in the period preceding puberty, and that calcium supplementation without physical activity does not improve the BMD acquisition during this period. Physical exercise that stimulates bone accretion needs a high calcium intake to be completely effective.     

Creatine supplementation: effects on urinary excretion and anaerobic performance

AIM: The aim of the present study is to investigate Urinary creatine (URCR) and urinary creatinine (URCRN) response to CR supplementation in conjunction with exercise performance. METHODS: Twenty-one sprint trained males were randomly divided into 3 groups. Each group followed a different CR dosage (10 g, 25 g and 35 g x day(-1) for 4 days) and placebo (Pl) in the 1(st) and 2(nd) week, respectively. A double-blind design was used. Subjects' urine was collected every 24 hours during the entire period of supplementation (SP). All groups, at the end of each SP performed 3 times the Anaerobic Wingate Test (AWT) with 6 min active recovery (60 rpm) on a cycle ergometer. RESULTS: Significantly (p<0.01) higher peak and mean power values were produced during the CR compared to Pl condition. A significant correlation (r=0.7, p<0.05) was also observed between peak power improvement (PPI) and URCR for the 3 groups. No such relationship was found between URCRN. Across all groups, URCR and URCRN increased significantly following ingestion compared with Pl (p<0.001). URCR post- supplementation presented a 7.4 fold, 36 fold and 21 fold increase for 10 g, 25 g and 35 g dose respectively, whilst URCRN presented a mean 2.4 fold increase for all different doses, which clearly shows the magnitude of sensitivity of these indices to CR supplementation. A strong correlation (r=0.95, p<0.01) observed between dose of CR ingestion and mean URCR (MRUCR) with prediction formula: CR = -0.936 + (5.613 x MRUCR) (SEE=3.5). CONCLUSION: URCR was an effective measure of each CR dosage administered as well as of the excretion pattern that each group followed throughout the SP. Furthermore the strong relationship of URCR and PPI could be particularly useful for monitoring and optimising CR loading in athletic populations.     

Radiofrequency-induced carcinogenesis: cellular calcium homeostasis changes as a triggering factor

The aim was to study the effects of radiofrequency (Rf) in a mice strain characterized by age-determined carcinogenesis of lymphatic tissues. Mice were treated with a 1?h/week Rf exposure for 4 months. A group submitted to sham exposure was used as control animals. The evolution of carcinogenesis was followed up to 18 months. The maximal life span of control mice was about 24 months. All dead animals were clinically and histologically examined to give an age-determined comparative quantification of the evolving carcinogenesis. A radiocalcium tracer method permitted the evaluation of Rf effects on transmembrane transport of extracellular calcium at 1 and 24 h after exposure. The determination of induced lipid peroxidation completed this second study. The findings show that Rf provoked an earlier general lymphocyte cell infiltration, formation of lymphoblastic ascites and extranodal tumours of different histological types, as well as an increased early mortality. The results suggest that in Rf-exposed mice, carcinogenesis may be induced earlier and with different pathological forms than in control animals. The modifications in cellular calcium homeostasis and the age-determined thymus involution appear to be important factors involved in this carcinogenesis process.     

Radiofrequency-induced carcinogenesis: cellular calcium homeostasis changes as a triggering factor

The aim was to study the effects of radiofrequency (Rf) in a mice strain characterized by age-determined carcinogenesis of lymphatic tissues. Mice were treated with a 1?h/week Rf exposure for 4 months. A group submitted to sham exposure was used as control animals. The evolution of carcinogenesis was followed up to 18 months. The maximal life span of control mice was about 24 months. All dead animals were clinically and histologically examined to give an age-determined comparative quantification of the evolving carcinogenesis. A radiocalcium tracer method permitted the evaluation of Rf effects on transmembrane transport of extracellular calcium at 1 and 24?h after exposure. The determination of induced lipid peroxidation completed this second study. The findings show that Rf provoked an earlier general lymphocyte cell infiltration, formation of lymphoblastic ascites and extranodal tumours of different histological types, as well as an increased early mortality. The results suggest that in Rf-exposed mice, carcinogenesis may be induced earlier and with different pathological forms than in control animals. The modifications in cellular calcium homeostasis and the age-determined thymus involution appear to be important factors involved in this carcinogenesis process.     

Exercise and training effects on blood haemostasis in health and disease: an update

In recent years, the dysfunction of the haemostatic system in relation to the clinical complications from arterioscleroses and cardiovascular diseases has become more recognised. Blood coagulation and fibrinolysis comprise two important physiological systems, which are regulated by a balance between activators and inhibitors. Activation of blood coagulation is associated with accelerated clot formation, whereas activation of blood fibrinolysis enhances the breakdown of the blood clot. Available evidence suggests that strenuous exercise induces activation of blood coagulation with simultaneous enhancement of blood fibrinolysis. Although the responses of blood coagulation and fibrinolysis appear to be related to the exercise intensity and its duration, recent reports suggest that moderate exercise intensity is followed by activation of blood fibrinolysis without concomitant hyper-coagulability, while very intense exercise is associated with concurrent activation of blood coagulation and fibrinolysis. Similar to blood coagulation and fibrinolysis, systemic platelet-related thrombogenic factors have been shown to be involved in the initiation and progression of atherogenesis and plaque growth. Although exercise effects on platelet aggregation and function in healthy individuals have been examined, the results reported have been conflicting. However, for patients with coronary heart disease, the balance of evidence available would strongly suggest that platelet aggregation and functions are increased with exercise. Few studies are available concerning the influence of training on blood coagulation and fibrinolysis and the exact effects of exercise training on the equilibrium between blood coagulation and fibrinolysis is not as yet known. Although the effects of physical training on platelets have been briefly investigated, available meagre evidence suggests that exercise training is associated with favourable effects on platelet aggregation and activation in both men and women.     

Alterations in calcium homeostasis and bone during actual and simulated space flight

The weightlessness experienced in space produces alterations in calcium homeostasis. Gemini, Apollo, and Skylab astronauts exhibited a negative calcium balance due primarily to hypercalciuria. In addition, the bone mineral density of the calcaneus declined by approximately 4% in Skylab crew members after 84 d of orbital flight. The negative calcium balance and loss of calcaneal bone mineral in normal adults subjected to prolonged bed rest was comparable to that observed in space. The pathogenesis of bone loss during space flight and bed rest is not well understood due to the lack of histomorphometric data. It is also uncertain whether osteoporotic changes in astronauts are corrected postflight. The observed bone loss would be reversible and of no long-term consequence if the only abnormality was an increased remodeling rate. However, altered bone cell activity would probably result in irreversible bone loss with the premature development of senile osteoporosis many years after space flight. The main skeletal defect in growing rats placed in orbit aboard Soviet Cosmos biosatellites appears to be diminished bone formation. Bone resorption was not elevated during weightlessness. Although cortical bone returned to normal postflight, the decline in trabecular bone mass was somewhat persistent. These studies established that the modeling of a growing skeleton was altered in a weightless environment, but do not necessarily imply that a remodeling imbalance occurs in adults during space flight. However, various forms of simulated space flight inhibited bone formation during both skeletal modeling and the remodeling of adult bone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of pelvic floor muscles in sportswomen: Quality of life and related factors

ObjectivesTo evaluate Maximum Voluntary Contraction (MVC) of the Pelvic Floor Muscles (PFM) in sportswomen, to observe the urinary symptoms and their impact on the Quality of Life (QoL).DesignObservational cross-sectional study.SettingGyms and teams in the North of Portugal.ParticipantsSportswomen (n = 197).Main outcome measuresThe measurement was performed using a manometer. The sportswomen were instructed to perform 3 MVC of the perineum, held for 3 s. The Kings Health Questionnaire (KHQ) was used to evaluate urinary symptoms and the QoL of the sportswomen.ResultsAge significantly influenced (p < 0.05) the QoL in all domains. An increase in BMI was also significantly associated with a decrease in the QoL. MVC values had a highly significant effect on the overall QoL and all domains, including a reduction in urinary symptoms. The weekly time of physical activity was associated with a better QoL in symptomatology. The practice of high-impact activities decreased the QoL (compared to low-impact activities). The vaginal resting pressure values ranged from 1.60 to 59.80 (24.34 ± 11.00).ConclusionsAge, BMI and high-impact sports appear to be the leading factors that promote the onset of SUI, which in turn decrease the QoL in sportswomen. There was a positive association between MVC and weekly time of physical activity in the QoL.     

Antiphospholipid antibodies, ischemic stroke in young adults, and calcium supplementation: a hypothesis

The proper treatment of younger patients who have suffered ischemic stroke and who have no stroke risk factors other than antiphospholipid antibodies is unsettled. We propose a rationale to support adding dietary supplementation with calcium and vitamin D to the present standard regimen of anticoagulant therapy for these patients. We expect that the benefits from this additional therapy will prove additive. Proving this hypothesis will require large numbers of patients unlikely to present to any one center. The military health care system is well suited to such a study.     

药物对缺氧细胞内钙离子浓度的影响

目的　比较三磷酸腺苷（ Ａ Ｔ Ｐ） 、三磷酸腺苷－ 氯化镁（ Ａ Ｍ） 、异搏停（ Ｖ Ｅ Ｒ） 和超氧化物歧化酶（ Ｓ Ｏ Ｄ） 防止细胞 Ｈ／ Ｒ 损伤时４５ Ｃａ 内流的效果。方法　应用人类小肠上皮细胞缺氧－ 再给氧（ Ｈ／ Ｒ） 模型及同位素示踪方法。结果　 Ａ Ｔ Ｐ、 Ａ Ｍ、 Ｖ Ｅ Ｒ 和 Ｓ Ｏ Ｄ 均可显著减少４５ Ｃａ 内流量,前３ 组细胞内４５ Ｃａ 含量低于 Ｓ Ｏ Ｄ 组。结论　 Ａ Ｔ Ｐ、 Ａ Ｍ、 Ｖ Ｅ Ｒ 和 Ｓ Ｏ Ｄ 均具有维持细胞钙稳态作用, Ｓ Ｏ Ｄ 效果逊于其它３ 组药物。     

Exercise and its effects on the central nervous system

Exercise can have profound effects on numerous biologic systems within the human body, including the central nervous system (CNS). The inherent complexity of the CNS, and the methodologic difficulties in evaluating its in vivo neurochemistry in humans, provide challenges to investigators studying the impact of exercise on the CNS. As a result, our knowledge in this area of exercise science remains relatively limited. However, advances in research technology are allowing investigators to gain valuable insight into the neurobiologic mechanisms that contribute to the bidirectional communication that occurs between the periphery and the CNS during exercise. This article examines how exercise-induced alterations in the CNS contribute to central fatigue and the overtraining syndrome, and how exercise can influence psychologic wellbeing and cognitive function.     

Exercise in the heat: effects of an adenosine antagonist

The purpose of this experiment was to examine the effects of an adenosine antagonist on cardiovascular, thermoregulatory, and exercise performance in the heat. Two doses (1 mg/kg and 10 mg/kg) of a selective adenosine A1 antagonist (1,3-di-n-propyl-8-[4-hydroxyphenyll]xanthine) (DPHPX) were tested in a rat model of exercise exhaustion, treadmill 11 m/min, 6 degrees incline, in the heat 30 degrees C. Pretreatment with the experimental adenosine antagonist caused a slight improvement p > 0.05 in run time (41+/-4 vs. 44+/-3 mm) at a low dose but reduced performance (41+/-4 vs. 29+/-3 mm) at a high dose despite elevated plasma lactate (6.41+/-0.82 vs. 9.91+/-1.0 and 12.42+/-1.1 micromole/L) levels in both dosage groups. At the low dose the antagonist provided a clear benefit in thermoregulation as evidenced by reduced heating rates (0.079+/-0.005 vs. 0.050+/-0.009 degrees C/min). Heart rate and blood pressure tended to be preserved in the low dose group also. Blood gases remained closer to normal with either dosage of drug with arterial PO2 being remarkably preserved after exercise whereas venous PO2 was not different suggesting increased oxygen delivery and extraction. The results of this investigation indicate that antagonizing the effects of adenosine at a low dose with this agent did improve cardiovascular and thermoregulatory responses but did not provide a substantial overall benefit in exercise performance in the heat.     

The effects of magnesium supplementation on exercise performance

PURPOSE: To determine the effects of magnesium (Mg2+) supplementation on performance and recovery in physically active women using the sensitive and recently advanced measure of ionic Mg2+ (iMg). METHODS: Participants (N = 121) were screened for [iMg] in plasma, with 44 (36.4%) exhibiting [iMg] below the normal range of 0.53-0.67 mmol.L-1 (4). Thirty-two subjects (21 +/- 3 yr) representing a broad range of [iMg] (0.54 +/- 0.04 mmol.L-1) completed the main 14-wk study. At baseline, participants submitted to a resting blood pressure measurement, and they completed both an anaerobic treadmill test and an incremental (aerobic) treadmill test. For the latter, values for workload, oxygen uptake, and heart rate were obtained at both anaerobic threshold and maximal effort. Blood samples for iMg, total serum Mg2+ (TMg), erythrocyte Mg2+ (EMg), Ca2+, K+, Na+, hemoglobin, hematocrit, lactate, and glucose were also collected pretest, and 4, 10, 30 min, and 24 h posttest. Subjects received 212 mg.d-1 Mg oxide or placebo in a double-blind fashion and were retested after 4 wk. After a 6-wk washout period, the testing was repeated with a treatment crossover. RESULTS: Ionic Mg2+ increased with Mg2+ treatment versus placebo (P < 0.05); however, performance and recovery indices were not significantly affected. CONCLUSION: Four weeks of 212 mg.d-1 Mg oxide supplementation improves resting [iMg] levels but not performance or recovery in physically active women.     

Exercise in hot and cold environments: differential effects on leukocyte number and NK cell activity

INTRODUCTION: Exercise and environmental temperature have been reported to affect the immune system, but few studies have examined the combined effects of very hot or cold temperatures during exercise in the same group of subjects. Therefore, the purpose was to examine the immune responses following exercise combined with exposure to hot and cold environments. METHODS: There were 10 men who completed 2 60-min cycle ergometry (60% VO2peak) trials: hot (HT: 38 degrees C, 45% RH) and cold (CD: 8 degrees C, 50% RH). Rectal core temperatures (Tc), average skin temperatures (Tsk), and HR were recorded every 15 min of exercise. Venous blood was collected before (PRE), immediately after (POST), 2 h after (2 h), and 24 h after exercise (24 h). Physiologic strain index (PSI) was calculated. Total and differential leukocytes were determined by manual counting (adjusted for plasma volume shifts). Natural killer cell activity (NKCA) was determined by a whole blood 51Cr-release assay. RESULTS: Tsk, Tc, and PSI were significantly lower in the CD than HT trial (p < 0.05). Total leukocyte count was greater POST (40%) and 2 h (74%) than PRE and 24 h in both conditions (p < 0.05). Neutrophil count was greater POST (49%) and 2 h (132%) than PRE and 24 h in both conditions (p < 0.05). Lymphocyte count was greater POST (24%) in HT than CD (p < 0.05). NKCA was greater POST (38%) than PRE, 2 h, and 24 h in both conditions (p < 0.05). HT caused significant increases for Tc and Tsk above those observed for CD (p < 0.05). PSI was greater in HT (9.92 +/- 0.93) than CD (4.24 +/- 0.56) (p < 0.05). DISCUSSION: Exercise in HT produced more physiological stress than CD; however, this difference was not manifested in the immune system response. Heat and cold stress in combination with exercise produce similar disturbances in immunity during recovery from exercise.     

L-carnitine supplementation in humans. The effects on physical performance

The use of supplementary L-carnitine by athletes has become rather widespread over the recent years even in the absence of unequivocal results from human experimental studies that might support this practice. To justify the above procedure, the most commonly purported reasons are that L-carnitine administration could hypothetically: 1. increase lipid turnover in working muscles leading to glycogen saving and, as a consequence, allow longer performances for given heavy work loads; 2. contribute to the homeostasis of free and esterified L-carnitine in plasma and muscle, the allegation being that the levels of one or more of these compounds may decrease in the course of heavy repetitive exercise. A critical survey of the literature on carnitine metabolism in healthy humans at exercise does not appear to be available. The authors are of the opinion that this paper, besides shedding light into some relevant aspects of energy turnover in muscle, could also be of practical use not only for the physiologists but particularly for the Sport Medicine practitioners.     

Exercise and training effects on gastric emptying of carbohydrate beverages

Carbohydrate containing drinks are commonly consumed as an ergogenic aid during endurance sports activities. The efficacy of a given drink is limited by the rate of absorption, which is in turn limited by gastric emptying. A myriad of factors influence gastric emptying. The influence of several of these factors (training status, exercise intensity, and carbohydrate composition) was investigated by repeated experiments using a nasogastric tube and a modification of the technique of George. A group of well-trained bicyclists and a group of untrained subjects performed similar experiments. Three different carbohydrate containing drinks (15 g.100 ml-1 glucose (G), 15 g.100 ml-1 maltodextrin plus 3 g.100 ml-1 fructose (MD), 7 g.100 ml-1 sucrose (I] and artificially sweetened water were compared during rest and 50 and 70% Wmax bicycling. Experimental design was crossover. There was a trend for the carbohydrate drinks to empty initially more slowly under the influence of exercise. Differences in drink volume remaining in the stomach were significant (P less than 0.05), with I at 10 min (70%, mean = 48.9%; rest, mean = 30.5%) and at 20 min (70%, mean = 28.9%; rest, mean = 23.8%) and with MD at 10 min (70%, mean = 71.1%; rest, mean = 55.9%). A similar trend was also seen with 50% Wmax exercise; however, this trend was only significant with MD at 10 min (50%, mean = 72.1%; rest, mean = 55.9%). Drink composition was a much stronger inhibitor of gastric emptying. However, all drinks emptied exponentially with fast-phase initial emptying rates. No differences in gastric emptying or secretion were observed between trained and untrained subjects.     

补钙预防妊娠期高血压病的临床研究

目的为了探讨补钙对预防妊娠期高血压病的效果,给临床提供合理的预防方案。方法将93例初产妇分成治疗组54例和对照组39例,治疗组孕妇给予口服葡萄糖酸钙直至分娩,对照组不服用任何的钙剂。结果 治疗组口服葡萄糖酸钙治疗后血钙的浓度得到提高,差异有统计学意义(P<0.05),而对照组的血钙浓度在孕36~37周下降明显,差异有统计学意义(P<0.05)。治疗组的缺钙症状发生率(16.7%)低于对照组(59.0%),同时治疗组的妊娠期高血压的发生率(3.8%)低于对照组(17.9%),上述症状的组间差异均有统计学意义(P<0.05)。结论妊娠是妇女的特殊生理时期,各种原因导致母体内血钙浓度下降,及时补充钙能够降低缺钙症状和妊娠高血压病的发生率,有助于胎儿的生长发育。     

The effects of creatine supplementation on performance and hormonal response in amateur swimmers

Objectives

The purpose of this study was to determine the influence of short-term creatine supplementation on sprint swimming performance (50 and 100 m) and hormonal responses (growth hormone, testosterone and cortisol).

Methods

Twenty amateur male swimmers ingested creatine monohydrate (CR) or a matched placebo (PL) for 6 days. All subjects performed 6 days, swimming exercise. The subjects were tested for performance and hormonal responses the day before and after this creatine loading.

Results

The mean swimming time of CR group in 50 m was significantly decreased (Before-period: 53.1 ± 3.73 s, after-period: 50.7 ± 2.84 s). Growth hormone and cortisol were not affected by this creatine loading. But, testosterone concentration was significantly greater in CR compared to PL after supplementation period (P < 0.05).

Conclusions

Our data suggest that short-term creatine supplementation has improved 50 m sprint performance in amateur swimmer and it seems unlikely creatine loading is hormonally mediated.