Effects of exercise and conditioning on clotting and fibrinolytic activity in men

Sixty healthy men in three physical fitness categories (sedentary, on no organized fitness program; joggers, running 5-15 miles/wk; and marathoners, running greater than 50 miles/wk) were evaluated for changes in blood clotting and fibrinolytic activity before and after maximum exercise on a treadmill according to the Bruce protocol. The rate of blood clotting, as measured by prothrombin times, partial thromboplastin times and thrombin times, was accelerated by exercise (all P less than 0.005). The ability of euglobulin clots and plasma clots to lyse incorporated 125I-fibrin, termed 125I-euglobulin clot lysis (IEL) and 125I-plasma clot lysis (IPCL), were used as indexes of fibrinolytic activity. Marathoners had greater increases in fibrinolytic activity with exercise (76% compared with 63% for joggers and 55% for sedentary subjects by IEL; 427% compared with 418% for joggers and 309% for sedentary subjects by IPCL; all P less than 0.05). Fibrin degradation products increased with exercise (P less than 0.005 for the total group of 60 subjects). The absolute concentrations of alpha 2-plasmin inhibitor, alpha 2-macroglobulin, and antithrombin III increased with exercise (all P less than 0.005), but when concentrations were corrected for acute shifts of plasma water during exercise, the quantity of these inhibitors actually decreased (all P less than 0.005). The changes in clotting assays with exercise were not significantly correlated with changes in whole blood lactate, blood pyruvate, or rectal temperatures. Fibrinolytic assays before and after exercise correlated poorly to moderately with blood lactates (IEL: r = 0.441 and r = 0.425, respectively; IPCL: r = 0.294 and r = 0.544, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women

[Purpose]This study aimed to investigate the effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women.[Methods] Thirty women in their twenties (n=15) and fifties (n=15) were enrolled. All subjects performed aerobic exercise on a treadmill for 10 min at 0% and 6% gradient repeatedly to elicit 50%, 60%, and 70% VO₂max.[Results]Energy expenditure and fat oxidation were higher during aerobic exercise at 6% of the gradient than at 0%, and there was no significant difference in carbohydrate oxidation in any age group.[Conclusion]Aerobic exercise at a 6% gradient was more favorable for fat oxidation than a 0% gradient in all age groups. In particular, in the case of women in their fifties, walking on a gradient of 6%, which is favorable for increasing fat oxidation, was more effective than walking on flat ground for preventing and reducing obesity. However, to examine the difference in fat oxidation among exercise intensities more accurately, exercise performed for longer than 30 min is required. Follow-up studies are required to investigate the effect of various gradients on physiological and metabolic characteristics when carrying out aerobic exercises for more than 30 min.     

Effects of prior exercise on exercise-induced arterial hypoxemia in young women

Twenty-eighthealthy women (ages 27.2 ± 6.4 yr) with widely varying fitnesslevels [maximal O₂consumption (O_{2 max}),31-70 ml · kg¹ · min¹]first completed a progressive incremental treadmill test to O_{2 max} (totalduration, 13.3 ± 1.4 min; 97 ± 37 s at maximal workload), rested for 20 min, and then completed a constant-load treadmill test at maximal workload (total duration, 143 ± 31 s). Atthe termination of the progressive test, 6 subjects had maintained arterial PO₂(Pa_O2) near resting levels, whereas 22 subjects showed a >10 Torr decrease inPa_O2 [78.0 ± 7.2 Torr, arterial O₂ saturation(Sa_O2), 91.6 ± 2.4%], andalveolar-arterial O₂ difference (A-aD_O2,39.2 ± 7.4 Torr). During the subsequent constant-load test, allsubjects, regardless of their degree of exercise-induced arterialhypoxemia (EIAH) during the progressive test, showed a nearly identicaleffect of a narrowed A-aD_O2(4.8 ± 3.8 Torr) and an increase inPa_O2 (+5.9 ± 4.3 Torr) andSa_O2 (+1.6 ± 1.7%) compared with atthe end point of the progressive test. Therefore, EIAH during maximalexercise was lessened, not enhanced, by prior exercise, consistent withthe hypothesis that EIAH is not caused by a mechanismwhich persists after the initial exercise period and is aggravated bysubsequent exercise, as might be expected of exercise-inducedstructural alterations at the alveolar-capillary interface. Rather,these findings in habitually active young women point to a functionallybased mechanism for EIAH that is present only during the exerciseperiod.

     

Effects of aerobic exercise on serum leptin levels in obese women

It has been demonstrated that leptin concentrations in obese patients may be altered by weight loss. We examined the effects of a 9-week aerobic exercise program on serum leptin concentrations in overweight women (20-50% above ideal body mass) under conditions of weight stability. Sixteen overweight women, mean (SE) age 42.75 (1.64) years, comprised the exercise group which adhered to a supervised aerobic exercise program. A graded exercise treadmill test was conducted before and after the exercise program to determine maximal oxygen uptake (VO2max) using open-circuit spirometry. The women demonstrated improved aerobic fitness (VO2max increased 12.29%), however, body fat and the body mass index did not change significantly [42.27 (1.35)-41.87 (1.33)%]. Fourteen women, age 40.57 (2.80) years, did not exercise over the same time period and served as a control group. Serum leptin levels were not significantly altered for either the exercise [28.00 (2.13)-31.04 (2.71) ng x ml(-1)] or the control group [33.24 (3.78)-34.69 (3.14) ng x mg(-1)]. The data indicate that 9 weeks of aerobic exercise improves aerobic fitness, but does not affect leptin concentrations in overweight women.     

Effects of chronic exercise and deconditioning on platelet function in women

Wang, Jong-Shyan, Chauying J. Jen, and Hsiun-Ing Chen.Effects of chronic exercise and deconditioning on plateletfunction in women. J. Appl. Physiol.83(6): 2080-2085, 1997.To investigate the effects of chronicexercise and deconditioning on platelet function in women, 16 healthysedentary women were divided into control and exercise groups. Theexercise group cycled on an ergometer at 50% maximal oxygenconsumption for 30 min/day, 5 days/wk, for two consecutive menstrualcycles and then were deconditioned for three menstrual cycles. Duringthis period, platelet adhesiveness on a fibrinogen-coated surface,ADP-induced platelet aggregation and intracellular calciumconcentration elevation, guanosine 3,5-cyclic monophosphate (cGMP) content in platelets, and plasma nitric oxide metabolite levels were measured before and immediately after a progressive exercise test in the midfollicular phase. Ourresults indicated that, after exercise training,1) resting heart rates and bloodpressures were reduced, and exercise performance was improved;2) resting platelet function wasdecreased, whereas plasma nitrite and nitrate levels and platelet cGMPcontents were enhanced; and 3) thepotentiation of platelet function by acute strenuous exercise wasdecreased, whereas the increases in plasma nitrite and nitrate levelsand platelet cGMP contents were enhanced by acuteexercise. Furthermore, deconditioning reversed these training effects. This implies that training-induced platelet functional changes in women in the midfollicular phase may be mediatedby nitric oxide.

     

Effects of human pregnancy and aerobic conditioning on alveolar gas exchange during exercise

This study examined the effects of aerobic conditioning during the second and third trimesters of human pregnancy on ventilatory responses to graded cycling. Previously sedentary pregnant women were assigned randomly to an exercise group (n = 14) or a nonexercising control group (n = 14). Data were collected at 15-17 weeks, 25-27 weeks and 34-36 weeks of pregnancy. Testing involved 20 W.min-1 increases in work rate to a heart rate of 170 beats.min-1 and (or) volitional fatigue. Breath-by-breath ventilatory and alveolar gas exchange measurements were compared at rest, a standard submaximal .VO2 and peak exercise. Within both groups, resting .V(E), .V(A), and V(T)/T(I) increased significantly with advancing gestation. Peak work rate, O2 pulse (.VO2/HR), .V(E), .V(A) respiratory rate, V(T)/T(I), .VO2, .VCO2, and the ventilatory threshold (T(vent)) were increased after physical conditioning. Chronic maternal exercise has no significant effect on pregnancy-induced changes in ventilation and (or) alveolar gas exchange at rest or during standard submaximal exercise. Training-induced increases in T(vent) and peak oxygen pulse support the efficacy of prenatal fitness programs to improve maternal work capacity.     

Effects of age and regular exercise on muscle strength and endurance

Twenty male and 20 female non-professional tennis players were classified into two different age groups (n = 10 per group): young active men (30.4 +/- 3.3 years), young active women (27.5 +/- 4.3 years), elderly active men (64.4 +/- 3.7 years), and elderly active women (65.3 +/- 4.5 years). These individuals were matched (n = 10 per group) according to sex, age, height and mass to sedentary individuals of the same socio-economical background: young sedentary men (29.2 +/- 3.4 years), young sedentary women (25.6 +/- 4.4 years), elderly sedentary men (65.2 +/- 3.2 years) and elderly sedentary women (65.6 +/- 4.4 years). An isokinetic dynamometer was used to measure the strength of the knee extensors and flexors (two separate occasions) and the endurance of the extensors. Vastus lateralis electromyogram (EMG) was measured concomitantly. Significant sex, age and exercise effects (P less than 0.001) were observed for peak torque of both muscle groups. The effect of age on extensor strength was more pronounced at high speeds where men were also able to generate larger relative torques than women. No age or sex effects were noted for muscle endurance. However, muscles of active individuals demonstrated a greater resistance to fatigue than those of sedentary individuals. In conclusion, men were found to be stronger than women, age was associated with a decrease in muscle strength, but not of muscle endurance, and tennis players were stronger and had muscles that were more resistant to fatigue than their sedentary pairs in both age groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of acute moderate-intensity exercise on carnitine metabolism in men and women

The purpose of this investigation was to describe the dynamics of carnitine metabolism during an acute episode of exercise. Twenty-eight subjects (14 male; 14 female) exercised for 40 min on a bicycle ergometer at 55% of their maximal aerobic capacities. Blood samples were obtained at rest, 10, 20, 30, and 40 min of exercise, and 15-min postexercise. Muscle biopsies of the vastus lateralis were performed before and after exercise. Results demonstrated that the percent of acylated plasma carnitine increased significantly (P less than 0.05) across all subjects from 17.3% at rest to 22.3% by 40 min of exercise and continued to increase to 22.8% 15-min postexercise. Total muscle carnitine levels fell significantly (P less than 0.001) across all subjects from 4.21 (1.27) (means +/- SD) mumol/g wet weight at rest to 3.29 (1.27) mumol/g wet weight after exercise. Well-trained males and females had almost identical levels of muscle carnitine [4.35(1.86) and 4.34 (0.64) mumol/g wet weight, respectively]. These levels were somewhat higher but not significantly higher than their moderately trained counterparts [3.86(1.34) and 4.28(1.18) males and females, respectively]. Carnitine palmitoyl transferase (E.C. 2.3.1.21) activity also declined significantly (P less than 0.05) across all subjects after exercise. This study is the first to demonstrate a potential loss of acylated carnitine forms from muscle to plasma during acute exercise, possibly reflecting an increase in carnitine turnover. Alterations in carnitine status may represent another metabolic adaptation to chronic exercise training.     

黑木耳对高脂血症家兔血液流变学的影响（英文）

通过检测家兔红细胞全血粘度、血浆粘度和血细胞压积等血液流变学参数研究黑木耳对高脂血症家兔血液流变学的影响,进而为其药用功能方面提供食用安全性的新量化依据。40只家兔随机分为5组,分别为控制组、高胆固醇模型组、黑木耳低剂量组、黑木耳中剂量组和高剂量组。高胆固醇模型组建模后,每4周检测一次血液流变学参数,持续检测20周。通过不同取血次数之间数据比较和组间数据比较,结果表明在饲喂黑木耳后家兔红细胞的全血粘度、血浆粘度和血细胞压积这些血液流变学参数都显著减低了(P0.05),并且发现中剂量组为成年雄新西兰鼠的最佳剂量。食用黑木耳预防高血脂症有一定的剂量依赖,黑木耳中剂量组能较好地改善高脂血症。     

Effects of acculturation and age on the exercise capacities of Solomon Islanders

Submaximal exercise tests were carried out on 197 females and 290 males from five populations in the Solomon Islands to determine how acculturation affects the fitness of different age and sex groups. Males and females in the least acculturated group show the highest fitness levels, reflecting strenuous work patterns. Subjects from the most acculturated groups exhibit the lowest levels of fitness, a consequence of their more sedentary life-styles. Unexpectedly, older females in these groups show exercise capacities that are equal to those of younger women. This may be a consequence of generational differences in the practice of traditional activities, such as those associated with gardening. Groups ranked intermediate in acculturation show variable patterns. For some age and sex groups, modernization has reinforced and even intensified strenuous activity patterns, resulting in high levels of fitness. For others, modernization has promoted inactivity and/or altered dietary patterns, resulting in increased body fat and low levels of fitness.     

Effect of exercise conditioning on excitation-contraction coupling in aged rats

We studied aged (24-26 mo) Fischer 344 rats after they underwent 8 wk of moderate exercise conditioning. Right ventricular papillary muscles were loaded with the calcium indicator aequorin. Electrophysiological recordings were also performed. Time to peak isometric tension in muscles from exercised aged rats (EAR) was shorter than in those from unexercised aged rats (UAR) (126 +/- 7 vs. 167 +/- 7 ms; P less than 0.01). Time to 50% relaxation from peak isometric tension was also shorter in EAR than in UAR (88 +/- 3 vs. 119 +/- 12 ms; P less than 0.05). There was a trend toward decrease in time to peak light and a significant decrease in time to 50% decline from peak light (33 +/- 4 ms in EAR vs. 59 +/- 17 ms in UAR; P = 0.001). Action potential amplitude was smaller in EAR than in UAR (67 +/- 4 vs. 82 +/- 3 mV; P = 0.003); however, action potential duration was longer (137 +/- 6 ms in EAR vs. 100 +/- 10 ms in UAR; P = 0.005). Right ventricular-to-body weight ratios revealed no evidence of hypertrophy in EAR compared with UAR. Cardiac tissue norepinephrine content was significantly greater in EAR than in UAR (1,212 +/- 25 vs. 630 +/- 105 ng/tissue; P = 0.02). In summary, exercise reversed the age-related prolongation of isometric contraction and associated intracellular calcium transient in the aged rat while it prolonged the transmembrane action potential. In addition, exercise in aged rats resulted in an increase in cardiac norepinephrine content.     

Effects of age on testosterone responses to resistance exercise and musculoskeletal variables in men

This study compared serum total testosterone (TT) and free testosterone (FT) responses of young (20-26 years, n = 8), middle-aged (38-53 years, n = 7), and older (59-72 years, n = 9) men to resistance exercise. We also examined the relationships between testosterone (T) levels and strength, bone mineral density (BMD), and body composition variables for each age group. Subjects were tested for isotonic muscular strength (1 repetition maximum [1RM]), BMD (dual-energy x-ray absorptiometry [DXA]) and body composition (DXA). Each group performed an acute exercise protocol (3 sets, 10 repetitions, 80% of 1RM, 6 exercises). Blood samples were obtained at baseline, immediately postexercise, and 15 minutes postexercise for the TT and FT assays. The older age group had significantly (p < 0.05) lower T levels than the young group, but each group exhibited an increase (p < 0.05) in TT and FT immediately postexercise. Total T and FT were significantly correlated (p < 0.05) with strength in middle-aged and older men and with bone-free lean tissue mass in older men. In conclusion, middle-aged and older men showed similar relative T responses to those of younger men to a single bout of high-intensity resistance exercise. However, T levels were related to strength and muscle mass only in middle-aged or older men. On a practical application level, older men can complete a high-intensity resistance exercise program resulting in spikes in T that may attenuate age-related muscle and BMD loss.     

Effects of atorvastatin on progression-regression of renal injury in hyperlipidemic chickens

Complex interrelationships exist between hyperlipidemia and the progression of renal injury. The aim of this study was to evaluate the impact of high plasma cholesterol and triglyceride levels on renal structure and the effects of atorvastatin on progression-regression of renal injury. One-hundred chickens were divided into five groups: Group A: Standard diet (SD) for 6 months; Group B: Hyperlipidemic diet (HD) for 6 months; Group C: HD for three months and SD during the next 3 months; Group D: HD for 3 months and SD during the next 3 months, when they received oral atorvastatin (3 mg/kg/d); Group E: HD for the whole 6 months, and atorvastatin (3 mg/kg/d) during the last 3 months. Increased alpha-actine immunostaining was found in glomeruli of groups B and C. An important decrease of immunostaining was observed in glomeruli of atorvastatin treated groups. Group D showed the lowest value for presence of lipids, and significant differences were found with respect to the rest of the groups. The glomeruli of group B presented the highest damage grades and those of group D showed the lowest grades and presented significant differences from the rest of the groups. The combination of atorvastatin therapy and proper diet proved to be effective in promoting renal disease regression. However, the study of several parameters indicates that neither only diet nor atorvastatin in the progression group resulted completely effective in decreasing the progression of the disease.