Adrenocorticotropic Hormone and Cortisol Levels in Athletes and Sedentary Subjects at Rest and Exhaustion: Effects of Magnesium Supplementation

The effects of a 1-month exercise program and magnesium supplementation on the adrenocorticotropic hormone and cortisol levels were studied in young tae-kwon-do and sedentary subjects both at rest and exhaustion. The hormone levels were compared before and after supplementation with 10 mg of magnesium (as magnesium sulfate) per kilogram of body weight. Both exercise and magnesium supplements caused significant increases of the adrenocorticotropic hormone (p < 0.05). The cortisol levels were increased in training subjects receiving supplements (p < 0.05) but not so in subjects that either trained or received magnesium supplements in an independent manner. The cortisol levels measured in resting individuals were higher in the supplemented and non-supplemented athletes than those in sedentary subjects (p < 0.05). The results of this study show that exercise and/or magnesium supplementation causes a rise of the adrenocorticotropic hormone, whereas cortisol is increased only as a result of combined exhaustion and magnesium supplements.     

Effects of Calcium Supplementation on Glucose and Insulin Levels of Athletes at Rest and After Exercise

This study was performed to determine how the calcium supplementation for a 4-week period affects the glucose and insulin levels at rest and at exhaustion in athletes. This is a 4-week study performed on 30 healthy subjects varying between 18 and 22 ages. Subjects were separated into three groups: first group (group supplemented with calcium, sedentary group), second group (calcium supplementations + exercise group), and third group (training group). Glucose and insulin parameters of the groups were measured four times, at rest and exhaustion in the beginning of the research and at rest and exhaustion after the end of 4 weeks application period. Exhaustion measurements both before and after the supplementations significantly decreased in compared to rest measurements in terms of insulin (p < 0.05). Significant difference was not determined in the glucose values of groups. In terms of glucose, values increased in all of the three groups occurred with exercise both before and after the supplementation by exercise and exhaustion (p < 0.05). The results of our study indicate that calcium gluconate supplementations for 4 weeks in sedentary subjects and athletes did not significantly affect plasma insulin levels at rest and exhaustion. However, glucose levels were affected by calcium supplementation and exhausting exercise in athletes.     

Calcium Supplementation and 4-Week Exercise on Blood Parameters of Athletes at Rest and Exhaustion

In the present study, experiments were designed to investigate if supplementation with calcium during 4 weeks had an effect on blood parameters in sedentary male athletes at rest and exhaustion. Thirty healthy subjects of ages ranging from 18 to 22 years were included in the study. The subjects were separated into three groups, as follows: Group 1 consisted sedentary athletes receiving 35 mg/kg/day calcium gluconate. Group 2 included subjects equally supplemented with calcium training 90 min/day for 5 days/week. Group 3 were subject to the same exercise regime but did not receive calcium supplements. Blood parameters were determined in the experimental subjects at rest and after exhaustion. The leukocyte count (WBC) of athletes in groups 2 and 3 were significantly higher at exhaustion (p < 0.05). There were no significant differences in the WBC of the two supplemented groups. The erythrocyte count (RBC) was increased in the supplemented athletes after training (p < 0.05), but hemoglobin, hematocrit, and trombocyte levels remained unchanged. The mean corpuscular volume increased in the calcium-supplemented group at rest (p < 0.05). These results suggest that calcium supplementation only causes increases in white and red blood cell counts in athletes after exhaustion while other hematological parameters remain unchanged.     

Effects of Vitamin E and Selenium on Serum Trace and Major Elements in Horses

The combined effects of vitamin E and selenium were studied in native Anatolian horses subject to strenuous exercise. The concentrations of copper, zinc, iron, calcium, potassium, and magnesium were determined in serum by atomic absorption spectrometry in two study groups (n = 25 each), one of which served as untreated controls. After exercising the horses by running 1,500 m in about 7 min, only the copper level and the copper/zinc ratio significantly increased (p < 0.05), but the concentrations of calcium, potassium, iron, and magnesium remained unchanged. In horses treated with vitamin E and selenium, the calcium and potassium levels decreased to levels lower than those of untreated controls before and after exercise. The iron levels were not changed by exercise or treatment alone but increased when the horses had been supplemented and exercised. The copper level and the copper/zinc ration increased as a result of exercise in both treated and untreated horses. These changes suggest that supplementation with vitamin E and selenium had an important effect on the serum concentrations of calcium, potassium, copper, iron, and the copper/zinc ratio.     

Plasma Zinc,Copper, and Serum Thyroid Hormones and Insulin Levels After Zinc Supplementation Followed by Placebo in Competitive Athletes

Intense physical activity is associated with biological adaptations involving hormones and trace elements. Zinc supplementation may affect plasma copper concentration, thyroid-stimulating hormone (TSH), thyroid hormones, insulin, and glucose homeostasis, but data in athletes are scarce. The aim of this study was to evaluate in competitive athletes (cyclists, n = 7, 32 ± 8 years) the effect of zinc supplementation (22 mg/day as zinc gluconate) during 30 days, and discontinuation using placebo (maltodextrin) during the following 30 days, on plasma zinc and copper concentrations, serum thyroid hormones, insulin and glucose levels, and HOMA2-IR. Compared to baseline, plasma zinc and Zn:Cu plasma ratio increased, but plasma copper decreased after zinc supplementation (day 30) and discontinuation (day 60) (p < 0.05). Zn supplementation and discontinuation had no effect on TSH, T3, and T4. Fasting serum insulin and HOMA2-IR increased (27% and 47%, respectively) on day 60 compared to baseline (p = 0.03), suggesting a delayed effect of zinc supplementation. Moreover, plasma zinc was positively associated with serum insulin (r = 0.87, p = 0.009) and HOMA2-IR (r = 0.81, p = 0.03) after zinc supplementation (day 30), indicating that supplemental zinc may impair glucose utilization in cyclists.     

SHBG,plasma, and urinary androgens in weight lifters after a strength training

Previous studies with different results have suggested that total and bioavailable testosterone levels are modified by physical exercise. Such changes may be related to modifications in cortisol levels and could be reflected in some urine androgens. To determine how weight lifting training may affect serum and urinary androgens, we measured total serum testosterone (T), cortisol, sex hormone binding globulin (SHBG) and urinary testosterone, epitestosterone, androsterone, and etiocholanolone, in a group of 19 elite weight lifters after 20 weeks of training. SHBG increased (from 27.5 ± 9.5 to 34.7 ± 8.1 nM, p < 0.05) whereas T/SHBG decreased significantly (from 1.10 ± 0.4 to 0.85 ± 0.3, p < 0.05). Serum total testosterone and cortisol did not change significantly. In urine, androsterone and etiocholanolone decreased significantly, whereas testosterone and epitestosterone remained unchanged. Changes in T/SHBG were related positively with changes in urinary androgens (r = 0.680, p < 0.01), and changes in SHBG were negatively related with changes in urinary androgens (r = −0.578, p < 0.01). These results suggest that intense physical activity may have an influence on the elimination of androgenic hormones due mainly to changes in their transporting protein SHBG.     

Specificity of resistance training responses in neck muscle size and strength

This study examined hypertrophy after head extension resistance training to assess which muscles of the complicated cervical neuromuscular system were used in this activity. We also determined if conventional resistance exercises, which are likely to evoke isometric action of the neck, induce generalized hypertrophy of the cervical muscle. Twenty-two active college students were studied. [mean (SE) age, weight and height: 21 (1) years, 71 (4) kg and 173 (3) cm, respectively]. Subjects were assigned to one of three groups: RESX (head extension exercise and other resistance exercises), RES (resistance exercises without specific neck exercise), or CON (no training). Groups RESX (n = 8) and RES (n = 6) trained 3 days/week for 12 weeks with large-muscle mass exercises (squat, deadlift, push press, bent row and mid-thigh pull). Group RESX also performed three sets of ten repetitions of a head extension exercise 3 days/week with a load equal to the 3 × 10 repetition maximum (RM). Group CON (n = 8) was a control group. The cross-sectional area (CSA) of nine individual muscles or muscle groups was determined by magnetic resonance imaging (MRI) of the cervical region. The CSA data were averaged over four contiguous transaxial slices in which all muscles of interest were visible. The 3 × 10 RM for the head extension exercise increased for RESX after training [from 17.9 (1.0) to 23.9 (1.4) kg, P < 0.05] but not for RES [from 17.6 (1.4) to 17.7 (1.9)␣kg] or CON [from 10.1 (2.2) to 10.3 (2.1) kg]. RESX showed an increase in total neck muscle CSA after training [from 19.5 (3.0) to 22.0 (3.6) cm², P < 0.05], but RES and CON did not [from 19.6 (2.9) to 19.7 (2.9)␣cm² and 17.0 (2.5) to 17.0 (2.4) cm², respectively]. This hypertrophy for RESX was due mainly to increases in CSA of 23.9 (3.2), 24.0 (5.8), and 24.9 (5.3)% for the splenius capitis, and semispinalis capitis and cervicis muscles, respectively. The lack of generalized neck muscle hypertrophy in RES was not due to insufficient training. For example, the CSA of their quadriceps femoris muscle group, as assessed by MRI, increased by 7 (1)% after this short-term training (P < 0.05). The results suggest that: (1) the splenius capitis, and semispinalis capitis and cervicis muscles are mainly responsible for head extension; (2) short-term resistance training does not provide a sufficient stimulus to evoke neck muscle hypertrophy unless specific neck exercises are performed; and (3) the postural role of head extensors provides modest loading in bipeds. Accepted: 15 October 1996     

Effects of amount of training on the saliva concentrations of cortisol, dehydroepiandrosterone and on the dehydroepiandrosterone: cortisol concentration ratio in women over 16 weeks of training

This study was designed to investigate in the saliva the influence in female athletes of handball or volleyball training on concentrations of cortisol [C], dehydroepiandrosterone [DHEA], and on the [DHEA]:[C] ratio over 16 weeks of training. Data were compared to those of sedentary women. Saliva samples were collected upon waking after an overnight fast during the 1st week (W₁) of the training programme and in the 16th week (W₁₆). The training programme increased the resting concentrations of saliva [DHEA] in all the sportswomen. In contrast, a decrease of [DHEA] was noted in the sedentary group (W₁₆ < W₁; P < 0.05). In none of the women did the [C] at rest change significantly during the study. Between W₁ and W₁₆, the [DHEA]:[C] ratio increased by more than 30% in all the sportswomen. In addition, the athletes with the highest performance levels and greatest amount of training had the lowest [DHEA]:[C] ratio. Negative linear relationships between the amount of training and the [DHEA]:[C] ratio were found both at W₁ (r = −0.53 P < 0.001), and W₁₆ (r=−0.73 P < 0.001), suggesting that the latter could be used as an indicator of the training status of sportswomen. Accepted: 12 May 1998     

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.     

Ventilation response to CO2 and exercise-induced hypoxaemia in master athletes

Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyper- pnoea. The aim of this study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation of the central chemoreceptors. The ventilation response to CO₂ was measured in nine elderly untrained men (UT) [mean age 66.3 (SEM 3.1) years] and nine master athletes (MA) [mean age 62.7 (SEM 0.8) years] at rest, during moderate exercise (40% maximal oxygen uptake, V˙O_2max), and during strenuous exercise (70% V˙O_2max) using the rebreathing method. Our results showed that the ventilation response to CO₂ did not differ with endurance training and/or exercise, that the threshold of the CO₂ response (Th) increased with exercise (P < 0.001), that the increase in Th in MA was higher than in UT between rest and moderate exercise [ΔTh_0–40: 8.55 (SEM 1.8) vs 3.06 (SEM 1.72) mmHg, P < 0.05], and that ΔTh_0–40 and Th during moderate exercise were negatively correlated with arterial O₂ saturation during maximal exercise (r = 0.50, P<0.05). We concluded therefore that exercise-induced hypoxaemia in master athletes may not be due to a lower ventilation response to CO₂, but may be partly related to a greater increase in Th during moderate exercise. Accepted: 18 August 1997     

Plasma Leptin,Plasma Zinc,and Plasma Copper Are Associated in Elite Female and Male Judo Athletes

The purpose of this study was to compare plasma leptin, plasma zinc, and plasma copper levels and their relationship in trained female and male judo athletes (n = 10 women; n = 8 men). Blood samples were obtained 24 h after training to measure plasma zinc, copper, and leptin levels. Subjects presented similar values to age (22 ± 2 years old), body mass index (24 ± 1 kg/m²), plasma zinc (17.2 ± 2 μmol/L), copper (12.5 ± 2 μmol/L), and leptin (5.6 ± 1.3 μg/L). However, height, total body mass, lean mass, fat mass, and sum of ten-skinfold thickness were higher in male than female. Plasma leptin was associated with sum of ten skinfolds in male (r = 0.91; p < 0.001) and female athletes (r = 0.84; p < 0.003). Plasma zinc was associated with leptin in males (r = 0.82; p < 0.05) while copper was associated with plasma leptin in females (r = 0.66; p < 0.05). Our results suggest that young judo athletes lost sex-related differences in leptin levels. Plasma zinc, plasma copper, and energy homeostasis may be involved in regulation of plasma leptin.     

The Impact of heat exposure and repeated exercise on circulating stress hormones

To determine if heat exposure alters the hormonal responses to moderate, repeated exercise, 11 healthy male subjects [age = 27.1 (3.0) years; maximal oxygen consumption, V˙O_2max = 47.6 (6.2) ml · kg · min⁻¹; mean (SD)] were assigned to four different experimental conditions according to a randomized-block design. While in a thermoneutral (23°C) or heated (40°C, 30% relative humidity) climatic chamber, subjects performed either cycle ergometer exercise (two 30-min bouts at ≈50% V˙O_2max, separated by a 45-min recovery interval, CEx and HEx conditions), or remained seated for 3 h (CS and HS conditions). Blood samples were analyzed for various exercise stress hormones [epinephrine (E), norepinephrine (NE), dopamine, cortisol and human growth hormone (hGH)]. Passive heating did not alter the concentrations of any of these hormones significantly. During both environmental conditions, exercise induced significant (P < 0.001) elevations in plasma E, NE and hGH levels. At 23°C during bout 1: E = 393 (199) pmol · l⁻¹ (CEx) vs 174 (85) pmol · l⁻¹ (CS), NE = 4593 (2640) pmol · l⁻¹ (CEx) vs 1548 (505) pmol · l⁻¹ (CS), and hGH = 274 (340) pmol · l⁻¹ (CEx)vs 64 (112) pmol · l⁻¹ (CS). At 40°C, bout 1: E = 596 (346) pmol · l⁻¹ (HEx) vs 323 (181) pmol · l⁻¹ (HS), NE = 7789 (5129) pmol · l⁻¹ (HEx) vs 1527 (605) pmol · l⁻¹ (HS), and hGH = 453 (494) pmol · l⁻¹ (HEx) vs 172 (355) pmol · l⁻¹ (HS). However, concentrations of plasma cortisol were increased only in response to exercise in the heat [HEx = 364 (168) nmol · l⁻¹ vs HS = 295 (114) nmol · l⁻¹). Compared to exercise at room temperature, plasma levels of E, NE and cortisol were all higher during exercise in the heat (P < 0.001 in all cases). The repetition of exercise did not significantly alter the pattern of change in cortisol or hGH levels in either environmental condition. However, repetition of exercise in the heat increased circulatory and psychological stress, with significantly (P < 0.001) higher plasma concentrations of E and NE. These results indicate a differential response of the various stress hormones to heat exposure and repeated moderate exercise. Accepted: 16 April 1997     

Competitive sustained exercise in humans, lymphokine activated killer cell activity, and glutamine – an intervention study

This study examined whether oral glutamine supplementation abolishes some of the exercise-induced changes in lymphocyte functions following long-term intense exercise. A group of 16 marathon runners participating in The Copenhagen Marathon 1996 were placed randomly in either a placebo (n = 7) or a glutamine receiving group (n = 9). Each subject received four doses of either placebo or glutamine (100 mg · kg⁻¹) administered at 0, 30, 60, and 90-min post-race. In the placebo group the plasma glutamine concentrations were lower than pre-race values during the post-exercise period [mean 647 (SEM 32) compared to 470 (SEM 22) μmol · l⁻¹ 90-min post-race, P < 0.05] whereas glutamine supplementation maintained the plasma glutamine concentration (at ∼750 μmol · l⁻¹). Glutamine supplementation in vivo had no effect on the lymphokine activated killer (LAK) cell activity, the proliferative responses or the exercise-induced changes in concentrations or percentages of any of the leucocyte subpopulations examined. Glutamine addition in in vitro studies enhanced the proliferative response in both groups. These data would suggest that decreased plasma glutamine concentrations post-exercise are not responsible for exercise-induced decrease in LAK activity and that the influence of glutamine in vitro is not dependent on the plasma glutamine concentration at the time of sampling. Accepted: 23 April 1998     

Hypothalamic-pituitary-adrenal and -gonadal axis function after exercise in sedentary and endurance trained elderly males

The aim of this study was to investigate hypothalamic-pituitary-adrenal (HPAA) and -gonadal (HPGA) axis responses to post-exercise (30 min at 65% V˙O_2max) combined corticotrophin, luteinizing hormone and thyrotrophin releasing hormone challenge (0.7 μg/kg body mass) in elderly distance runners (DR; age: 68.9 ± 4.2 year) and sedentary individuals (SI; age: 69.1 ± 2.6 year). Plasma cortisol, growth hormone, prolactin, luteinizing hormone, follicle stimulating hormone and total testosterone (T) concentrations pre- and post-exercise as well as in response to stimulation did not differ between DR and SI. Plasma adrenocorticotropic hormone returned to pre-exercise level in DR 60 min and in SI 90 min post-stimulation. Free T was lower in DR at all time points. Our results do not support the notion of altered releasing hormone-stimulable HPAA and HPGA synthesis-secretion capacity in elderly males after endurance training. Accepted: 18 November 1997     

Elements in Sera of Elite Taekwondo Athletes: Effects of Vitamin E Supplementation

Many researchers have emphasized the relation between nutrition and development and sustaining performance. Two methods are commonly employed to identify the interaction between physical activity and nutrition. The first consists of administering food with a variety of contents to people engaged in physical activity and observing their performance responses, and the other is concerned with determining the effects of physical activity on nutrition. Therefore, it can be said that there has been a growing interest in the explorations into the relation between exercise and vitamins, minerals, and elements. The present study reports the effects of 6 weeks administration of 300 mg/day vitamin E on the distribution of serum elements in elite taekwondo athletes. Seven male athletes, mean ages 22.1 ± 0.5 years weighing on average 66.4 ± 2.4 kg were included in the study. The athletes had been practicing taekwondo for 10–12 years. Resting blood samples were collected in duplicate before and after supplementation for determination of serum levels of cobalt, boron, cadmium, chromium, nickel, manganese, sulfur, copper, iron, zinc, phosphorus, sodium, potassium, and calcium. Supplementation resulted in significant increases of all elements relative to values before supplementation (p < 0.001), with the exception of boron and sulfur, which remained without change. The results of the present study demonstrate that vitamin E supplementation crucially influences the element and mineral metabolism in elite athletes.     

Treadmill exercise suppresses muscle cell apoptosis by increasing nerve growth factor levels and stimulating p-phosphatidylinositol 3-kinase activation in the soleus of diabetic rats

We investigated the effects of treadmill exercise performed regularly for 6 weeks on the levels of nerve growth factor (NGF), tyrosine kinase A and p75 receptors, phosphatidylinositol 3-kinase (PI3-K), mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk) 1,2, cyclic AMP response element-binding protein (CREB), and caspase-3 in the soleus of rats with streptozotocin (STZ)-induced diabetes. Thirty-two male Sprague–Dawley rats were divided into the following four groups: (1) normal control group (NCG; n = 8), (2) normal exercise group (NEG; n = 8), (3) diabetes control group (DCG; n = 8), and (4) diabetes exercise group (DEG; n = 8). Diabetes was induced by intraperitoneal injection of STZ (55 mg/kg dissolved in 0.05 M citrate buffer, pH 4.5). Rats were subjected to treadmill exercise 5 days a week for 6 weeks. The protein level of NGF significantly increased in the NEG and DEG (p < 0.001), whereas the levels of tyrosine kinase A and p75 receptors significantly increased in the NEG (p < 0.001). The levels of t-PI3-K, p-PI3-K, and p-CREB, and the p-CREB/t-CREB ratio significantly increased in the NEG (p < 0.001, respectively). The p-PI3-K/t-PI3-K ratio significantly increased in the DEG (p < 0.001). The p-Erk1/t-Erk1 ratio significantly increased in the NEG (p < 0.001), whereas the p-Erk2/t-Erk2 ratio significantly decreased in the DCG and DEG (p < 0.001). The caspase-3 level significantly increased in the DCG compared with that in the DEG (p < 0.001). These results suggest that treadmill exercise increases NGF levels and accelerates p-PI3-K activation in order to suppress apoptotic cell death in the soleus muscle of diabetic rats.     

Body composition and isokinetic strength of professional Sumo wrestlers

The purpose of this study was to investigate the profiles of body composition and force generation capability in professional Sumo wrestlers. The subjects were 23 professional Sumo wrestlers [mean age 22.0 (SEM 1.2) years] including those ranked in the lower- (Jonokuchi, n = 10), middle- (Sandanme, n = 8) and higher-division (Makuuchi, n = 5), 22 weight-classified athletes [5 judo athletes, 5 wrestlers, and 12 weight lifters, mean age 20.7 (SEM 0.7) years], and 21 untrained men [mean age 20.1 (SEM 0.2) years]. In the Sumo wrestlers, body mass ranged between 77.0 and 150.0 kg, body mass index between 25.9 and 44.5 kg · m⁻², relative fat mass (%FM) between 11.9 and 37.0%, and fat-free mass (FFM) between 59.1 and 107.6 kg. The Sumo wrestlers showed significantly higher %FM and smaller elbow and knee extensor cross-sectional areas (CSA) than the weight-classified athletes who weighed from 90.4 kg to 133.2 kg. Moreover, isokinetic forces in the flexion and extension of elbow and knee joints, respectively, at three constant velocities of 1.05, 3.14 and 5.24 rad · s⁻¹ were significantly lower in the Sumo wrestlers than in the weight-classified athletes and untrained subjects when expressed per unit of body mass. However, the median value of FFM relative to body height in the higher-division Sumo wrestlers was ranked high in the range of magnitude among those reported previously in the literature for heavyweight athletes. Moreover, the results on the comparisons within the Sumo wrestlers showed that not only FFM but also force generation capability, expressed both as an absolute term and as a value relative to both body mass and muscle CSA, might be factors contributing to the performance of Sumo wrestlers. Accepted: 18 August 1997     

Effect of Magnesium Supplementation on Some Plasma Elements in Athletes at Rest and Exhaustion

The effects of magnesium supplementation on plasma magnesium, zinc, and copper levels were determined in young adult tae-kwon-do athletes and sedentary controls at rest and exhaustion. After a 4-week supplementation period with 10 mg/day/kg Mg, the plasma magnesium, copper, and zinc levels significantly increased in sedentary and training (90–120 min training 5 days a week) subjects when compared to nonsupplemented controls (p < 0.05).     

Resistance exercise training and the orthostatic response

Resistance exercise has been suggested to increase blood volume, increase the sensitivity of the carotid baroreceptor cardiac reflex response (BARO), and decrease leg compliance, all factors that are expected to improve orthostatic tolerance. To further test these hypotheses, cardiovascular responses to standing and to pre-syncopal limited lower body negative pressure (LBNP) were measured in two groups of sedentary men before and after a 12-week period of either exercise (n = 10) or no exercise (control, n = 9). Resistance exercise training consisted of nine isotonic exercises, four sets of each, 3 days per week, stressing all major muscle groups. After exercise training, leg muscle volumes increased (P < 0.05) by 4–14%, lean body mass increased (P = 0.00) by 2.0 (0.5) kg, leg compliance and BARO were not significantly altered, and the maximal LBNP tolerated without pre-syncope was not significantly different. Supine resting heart rate was reduced (P = 0.03) without attenuating the heart rate or blood pressure responses during the stand test or LBNP. Also, blood volume (¹²⁵I and ⁵¹Cr) and red cell mass were increased (P < 0.02) by 2.8% and 3.9%, respectively. These findings indicate that intense resistance exercise increases blood volume but does not consistently improve orthostatic tolerance. Accepted: 17 January 1997     

The effect of gender on left ventricular function immediately after the wingate test

The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years] volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction effect with stroke volume (P < 0.05) was characterized by a decrease in the men and an increase of stroke volume in the women. Cardiac output rose significantly (P < 0.05) up to 14.5 (SD 6) l · min⁻¹) for the men and 12.1 (SD 4) l · min⁻¹ for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) l · min⁻¹, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P < 0.05). During exercise these differences showed an interaction effect (P < 0.05). These results would indicate that normal men and women respond to sudden strenuous exercise by reducing their left ventricular systolic function, with a significantly greater decrease in women (P < 0.05). The gender differences in the haemodynamic responses during the present study, may, as suggested by others, be attributable to differences in energy metabolism. In addition, changes in Doppler parameters of aortic flow, haemodynamics and blood pressure responses during sudden strenuous exercise differed markedly from those seen before with endurance exercise. Accepted: 8 January 1997