Postprandial lipemia: effects of intermittent versus continuous exercise

PURPOSE: The purpose of this study was to assess whether exercise performed in continuous and discontinuous formats reduced postprandial lipemia to a similar degree. METHODS: Fifteen normolipidemic and three borderline hyperlipidemic healthy males (ages 30.6 +/- 9.0 (mean +/- SD) yr, BMI 23.1 +/- 1.4 kg.m-2) participated in three trials, each conducted over 2 d. Subjects refrained from exercise for the 2 d preceding each trial. On day one, subjects rested (control trial), or ran at 60% of maximal oxygen uptake in either one 90-min session (continuous exercise trial), or three 30-min sessions (intermittent exercise trial). On day two, subjects ingested a high-fat test breakfast (1.2 g fat, 1.2 g carbohydrate, 70 kJ energy per kilogram body mass). Blood samples were obtained in the fasted state and at intervals for 6 h postprandially. RESULTS: Fasting plasma triacylglycerol (TAG) concentrations did not differ between trials. Areas under the TAG versus time curves were 18.1 +/- 6.7% (mean +/- SEM) and 17.7 +/- 7.6% (both P < 0.05) lower than control in the continuous exercise and intermittent exercise trials, respectively. Plasma glucose responses to the test meal did not differ between trials, but the serum insulin response was lower in the intermittent exercise trial compared with that in the control. CONCLUSION: The results suggest that both intermittent and continuous exercise can reduce postprandial lipemia.     

Norepinephrine response to exercise at the same relative intensity before and after endurance exercise training

It is well documented that endurance exercise training results in a blunted norepinephrine (NE) response to exercise of a given absolute exercise intensity. However, it is not clear what effect training has on the catecholamine response to exercise of the same relative intensity because previous studies have provided conflicting results. The purpose of the present study was, therefore, to determine the catecholamine response to exercise of the same relative exercise intensity before and after endurance exercise training. Six women and three men [age 28 +/- 8 (SD) yr] performed 10 wk of training. Maximal O2 uptake (VO2 max) was determined during treadmill exercise. Fifteen-minute treadmill exercise bouts were performed at 60, 65, 70, 75, 80, and 85% of VO2 max before and after training. VO2 max was increased by 20% (from 39.2 +/- 7.7 to 46.9 +/- 8.1 ml. kg-1. min-1; P < 0.05) in response to training. Plasma NE concentrations were higher (P < 0.05) during exercise at the same relative intensity after, compared with before, training at 65-85% of VO2 max. Differences between heart rates and plasma epinephrine concentrations after, compared with before, training were not statistically significant. These results provide evidence that the NE response to exercise is dependent on the absolute as well as the relative intensity of the exercise.     

Haemodynamic and metabolic responses of the lower limb after high intensity exercise in humans

Beta-galactosidase activity is known to exist in Drosophila melanogaster, but a detailed analysis of the tissue-specific patterns of activity has not previously been reported. Such an analysis is of particular interest because Drosophila is commonly used for making transformants that carry fusion genes in which the E. coli beta-galactosidase gene, lacZ, is used as a reporter gene. When these transformants are analyzed for beta-galactosidase activity by using chromogen X-gal staining, the method does not distinguish true fusion-gene activity from endogenous beta-galactosidase activity or from the beta-galactosidase activity of bacterial contaminants. Therefore, detailed maps of endogenous beta-galactosidase activity in this organism would help to prevent errors in data interpretation and would indicate which stages were most appropriate for experiments with the lacZ transformants. We have constructed such maps by applying X-gal staining methods to serial frozen sections and whole mounts of larval, prepupal, pupal, and adult stages of D. melanogaster reared under axenic conditions. Results showed endogenous beta-galactosidase activity in a variety of organs including the larval intestine, spiracles, lymph glands, cellular epidermis, and eye-antenna imaginal discs; the pupal cellular epidermis, lymph glands, imaginal tissues, fat body, and spiracle; and the adult pericardial cells, thoracic nephrocytes, ventriculus, and reproductive system. The good correlation between staining and metamorphic remodeling and phagocytic activity indicates that endogenous beta-galactosidase is physiologically interesting.     

The influence of exercise intensity on sweating efficiency of the whole body in a mild thermal condition

The photodegradation of seven carbamate pesticides (bendiocarb, isoprocarb, promecarb, ethiofencarb, furathiocarb, fenoxycarb and pirimicarb), in aqueous solution, has been examined by GC-MS. The most general result was formation of the corresponding phenols. Irradiation of isoprocarb and promecarb also resulted in photo-Fries rearrangement to ortho- and para-hydroxybenzamides. In the case of ethiofencarb photocleavage of the carbon-sulfur bond gave 2-methylphenyl methylcarbamate as main product. Likewise, N-S bond cleavage occurred upon irradiation of furathiocarb, to allow the formation of the carbamate insecticide carbofuran, butyl methylcarbamate and carbofuranphenol. Under similar conditions, fenoxycarb gave p-phenylphenol and 2-hydroxydibenzofuran, through primary homolysis of the aryloxy-methylene bond. Finally, pirimicarb gave rise to 2-formylamino-5,6-dimethylpyrimidin-4-yl dimethylcarbamate.     

The effect of exercise intensity on lipid peroxidation

This study characterizes exercise-induced lipid peroxidation during graded aerobic exercise in seven healthy men and women (36.4 +/- 3 yr). Levels of ethane and pentane in expired breath during cardiopulmonary exercise stress testing were measured at rest, lactic acidosis threshold (LAT), maximal exercise (VO2max), and recovery. Serum malonaldehyde (MDA) levels were measured at rest before exercise and 5 min after maximal exercise. Expired ethane and pentane flux levels were increased above resting levels at LAT, continued to rise at VO2max, then declined during recovery. Serum MDA levels were not significantly different before and after maximal exercise. Substantial exercise-induced lipid peroxidation (by expired ethane and pentane) apparently occurred in healthy individuals at LAT and continued to increase at VO2max, yet rapidly attenuated during post-exercise recovery. These findings indicate that in healthy individuals physical exercise induced lipid peroxidation transiently and that there was a removal of lipid peroxidation byproducts during recovery.     

Urea kinetics in humans at two levels of exercise intensity

A primed constant infusion of [15N2]urea was used to quantify the response of urea production to exercise at 40 and 70% maximal oxygen consumption on a treadmill. Total urea production, urea production from recycled N, urea production from nonrecycled N, and urea N recycled back into body protein were calculated. Most components of urea kinetics were unaffected by exercise at either intensity. The rate of urea reincorporated into protein was significantly increased during exercise and recovery at both levels of exercise. We conclude that exercise does not stimulate urea production but that there may be an accelerated reincorporation of urea N back into body protein.     

Reduced adipose tissue lipoprotein lipase responses, postprandial lipemia, and low high-density lipoprotein-2 subspecies levels in older athletes with silent myocardial ischemia

BACKGROUND: Radioimmunoguided surgery (RIGS) by means of radiolabeled monoclonal antibodies and a probe has been reported to be useful in recognizing subclinical tumor deposits during operation. Aim of this study was to understand the limits of this technique and to assess the potential diagnostic use of RIGS in colorectal cancer surgery. METHODS: Monoclonal antibody B72.3 reacting with TAG 72 antigen, labeled with iodine 125, was injected in 32 patients with primary tumors and in 22 patients with recurrent colorectal cancer. One hundred thirty-three suspected tumor sites were evaluated during operation by means of probe and resected with immunohistochemistry as control. RESULTS: Primary tumor sites were localized by RIGS in 60% of cases, and recurrent sites were localized in 82% of cases. There was a significant correlation both for primary (p < 0.001) and recurrent (p < 0.001) tumor sites between intraoperative RIGS findings and TAG 72 tumor antigen expression. Results obtained with the probe were instrumental in modifying the surgical approach in six (27%) of 22 patients with recurrences, allowing the removal of tumor masses that would otherwise have been overlooked. CONCLUSIONS: The results of RIGS seems to be encouraging in terms of clinical use. The potential high diagnostic resolution appears to improve surgical ablation of colorectal cancer, especially in patients with recurrent cancer or suspected recurrent tumors who have negative results for intraabdominal disease by all other roentgenographic criteria with rising carcinoembryonic antigen or TAG 72 antigen levels.     

Predicting walking intentions and exercise in individuals with intermittent claudication: An application of the theory of planned behavior.

Objective: To identify determinants of intention and walking activity among individuals with intermittent claudication using the theory of planned behavior. Study Design and Participants: Prospective, correlational study of men and women (n = 62) with intermittent claudication. Method: Baseline questionnaire assessing theory of planned behavior measures regarding walking. Telephone follow-up assessing frequency and duration of walking during the previous week. Results: Attitudes, subjective norms, and perceived behavioral control explained 67% of the variance in intentions. Perceived behavioral control explained 8% of the variance in walking activity. Conclusion: Findings support the theory of planned behavior for predicting intentions and warrant future examination of perceived behavioral control as a determinant of exercise. A basis for developing interventions to facilitate walking among this population is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coronary vasomotion during dynamic exercise: influence of intravenous and intracoronary nicardipine

OBJECTIVES: Our aim was to evaluate the influence of a calcium channel blocking agent of the dihydropyridine group (nicardipine) on coronary vasomotion during dynamic exercise. BACKGROUND: Coronary vasomotion plays an important role in the pathophysiology of myocardial ischemia. METHODS: Twenty-nine patients with coronary artery disease were studied at rest and during bicycle exercise with the use of biplane quantitative coronary angiography. Twelve patients without pretreatment (group 1) served as control subjects. Seventeen patients (group 2) received nicardipine, either 0.2 mg by intracoronary injection (n = 9) or 2.5 mg intravenously (n = 8) before exercise. RESULTS: In the control group there was exercise-induced vasoconstriction (-29%, p < 0.001) of the stenotic segment but coronary vasodilation (+22%, p < 0.05) of the normal vessel segment. In group 2, nicardipine induced coronary vasodilation of both the normal (+16%, p < 0.001) and the stenotic vessel segment (+35%). During subsequent exercise there was some additional vasodilation of normal (+4%, p = NS) and stenotic arteries (+5%, p = NS). There was no difference between either intracoronary or intravenous nicardipine with regard to vasodilation. Application of sublingual nitroglycerin was associated with significant vasodilation of the normal vessel segment in groups 1 (+18%, p < 0.05) and 2 (+15%, p < 0.001). The stenotic vessels showed a significant increase in percent cross-sectional area after nitroglycerin in groups 1 (+12%, p = NS) and 2 (+51%, p < 0.001). Exertional angina pectoris occurred less frequently in group 2 (18%) than in group 1 (67% [p < 0.005 vs. group 2]); group 2 also had a smaller increase in mean pulmonary artery pressure (+14 vs. +21 mm Hg, p < 0.05). CONCLUSIONS: Exercise induces vasoconstriction of stenotic, but vasodilation of normal, coronary vessel segments. Intravenous and intracoronary nicardipine prevent vasoconstriction of stenotic coronary arteries during exercise and exert a significant anti-ischemic effect. The combination of two anti-ischemic drugs, nitroglycerin and nicardipine, has an additive effect on coronary vasomotion that is seen only in the stenotic vessel segment. Thus, the anti-ischemic action of nicardipine is mainly due to a primary effect on coronary vasomotor response rather than to secondary effects such as changes in loading conditions.     

Effects of drugs on walking after spinal cord injury

Clonidine, a noradrenergic agonist, and cyproheptadine, a serotonergic antagonist, have each been associated with improved walking in SCI subjects. Baclofen, a GABA agonist, is frequently prescribed for spasticity but its effects on walking have not been well quantified. The objective of this study was to compare the effects of clonidine, cyproheptadine and baclofen on walking in SCI subjects with incomplete injuries. A motorized treadmill was used and harness support provided when necessary. A repeated single-subject design was employed for the twelve subjects. The greatest effects were found in more severely disabled subjects. Cyproheptadine was associated with greatly reduced need for assistance, increases in maximum treadmill speed (MTS) and reduced clonus. Clonidine was associated with increases in MTS and a generally more upright posture. Baclofen was associated with minor changes in walking. In many cases of drug effects, MTS increases and other changes were retained following washout of drugs. The significance and implications of the drug effects and the retention of effects during washout periods are discussed. It is concluded that clonidine and cyproheptadine have different effects but both appear useful for severely disabled SCI subjects. The effects of baclofen on walking after spinal cord injury remains unclear.     

Does walking speed influence the time pattern of muscle activation in normal children?

Dynamic electromyography (EMG) of the extrinsic muscles of the ankle is used more and more frequently to assist in the planning of tendon transfers in children with equinovarus deformities. Since these children walk at low speeds (1 to 4km/h), and since walking speed modifies the EMG-time pattern, the clinical investigator must be able to differentiate EMG modifications due to pathology versus those due to slow walking speed. The aim of this work was to study the effect of walking speed on the EMG-time pattern of the extrinsic ankle muscles in healthy children between 4 and 11 years of age. This pattern was found to change significantly with speed of progression but is independent of growth over this age range. A nomograph of EMG timing, taking into account walking speed, is proposed for clinical gait analysis.     

含碳球团的还原性和还原冷却后的强度

在1273~1573 K条件下研究了不同煤种、木炭和石墨与不同种类矿石制成含碳球团的还原速度;进而讨论了温度、配碳比(C/O)、挥发分含量等因素对含碳球团还原所需时间和金属化率的影响.通过测定含碳球团还原冷却后的强度,对影响强度因素进行了分析.还原冷却后的强度在温度1273 K时较低,配入含挥发分较高的气煤,可以使还原冷却后的强度提高,加快反应速度.     

Adipose tissue cell size and lipolysis in the rat: response to exercise intensity and food restriction

This experiment was designed to determine if the adaptive increase in adipose tissue epinephrine-stimulated lipolysis (ESL) observed in exercise trained rats is related to decreased adipocyte size or a direct response to exercise. Two levels of treadmill exercise and three levels of food restriction were imposed on male rats over a 12 week experimental period to create a distribution of adipose tissue cell sizes. Epinephrine-stimulated lipolysis was subsequently measured in the isolated adipocytes from rats trained at two different exercise levels and in untrained rats fed either ad libitum or 16%, 27%, or 35% dietary restriction. Energy restriction was effective in reducing body weight and to some extent epididymal fat pad weight; however, adipocyte size and number were not significantly affected. Exercise in both groups of trained rats was effective in reducing adipocyte size; however, cell size did not differ between training groups. The group receiving the greatest amount of daily exercise had significantly greater ESL indicating that the adaptive increase in lipolytic potential seen in adipose tissue of exercise trained rats is a true metabolic adaptation not secondary to reduced cell size.     

The Doppler illusion: The influence of dynamic intensity change on perceived pitch.

Four studies illustrate a new auditory illusion associated with the Doppler effect and demonstrate a new influence of dynamic intensity change on perceived pitch. Experiment 1 confirmed the existence of a popular belief that the pitch of a moving sound source rises as the source approaches. Because there is no corresponding rise in frequency, the authors refer to the perceived pitch rise as the Doppler illusion. Experiment 2 confirmed that the effect occurs perceptually, so the belief in a "naive principle" of physics has a perceptual basis. Experiment 3 confirmed the effect does not occur under matched static conditions. Experiment 4 showed that the influence of dynamic intensity change on perceived pitch occurs outside the realm of Doppler stimuli. The findings support a dynamic dimensional interaction of pitch and loudness, with marked differences in the perception of pitch and loudness under static and dynamic conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relation of low and moderate intensity exercise with acute mood change in college joggers

This study investigated a possible relationship between exercise intensity and mood alteration that commonly is associated with physical activity. 91 college students completed the Profile of Mood States before and after 20 min. of jogging at three intensities: 55%, 75%, and 79% of age-adjusted maximum heart rate on different occasions. Exercisers also completed a demographic inventory, a Lie Scale, and the State-Trait Anxiety Inventory. Contrary to our expectations, the interaction between exercise intensity and pre-post mood benefits was not significant. Supporting the manipulation of exercise intensity, the univariate interaction between exercise intensity and pre-post exercise scores on Fatigue was significant. Joggers reported short-term mood benefits on the combined subscales of the Profile of Mood States, and each subscale contributed to the benefits. Thus, regardless of the low- or moderate-intensity, participants reported that they "felt better" after exercising.     

Effect of exercise intensity on free tryptophan to branched-chain amino acids ratio and plasma prolactin during endurance exercise

The potential of exercise-induced changes in peripheral amino acids to alter blood prolactin levels through a serotonergic system modification was investigated in 8 male athletes. In two trials, subjects (N = 8) exercised on a cycle ergometer for 5 hr. The intensity of exercise corresponded to 55% VO2max (T55) or 75% VO2max (T75), respectively. In each trial, each subject received a 25-g energy bar (111 kcal) every 60 min, as well as 300 ml of a 6% carbohydrate solution (90 kcal) every 30 min of exercise duration. Plasma glucose and insulin declined (p < or = .05) in both trials during exercise. Ammonia was augmented (p < or = .05) above the baseline concentration after 120 min in both trials. During the last 2 hr of exercise, plasma free fatty acids were higher (p < or = .05) in T75 than in T55. During this time, the plasma free TRP/BCAA ratio was also augmented (p < or = .05) in T75, while no change was induced in T55. Plasma prolactin did not change in T55, while an increase (p < or = .05) was found in T75. The findings may further support the hypothesis that during endurance exercise changes in peripheral amino acid concentration may influence prolactin response via serotonergic system modifications.     

Adherence to exercise prescriptions: Effects of prescribing moderate versus higher levels of intensity and frequency.

Sedentary adults (N = 379) were randomly assigned in a 2 x 2 design to walk 30 min per day at a frequency of either 3-4 or 5-7 days per week, at an intensity of either 45%-55% or 65%-75% of maximum heart rate reserve. Analyses of exercise accumulated over 6 months showed greater amounts completed in the higher frequency (p = .0001) and moderate intensity (p = .021) conditions. Analyses of percentage of prescribed exercise completed showed greater adherence in the moderate intensity (p = .02) condition. Prescribing a higher frequency increased the accumulation of exercise without a decline in adherence, whereas prescribing a higher intensity decreased adherence and resulted in the completion of less exercise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reduction of postprandial hyperglycemia and frequency of hypoglycemia in IDDM patients on insulin-analog treatment. Multicenter Insulin Lispro Study Group

Insulin lispro, an insulin analog recently developed particularly for mealtime therapy, has a fast absorption rate and a short duration of action. We compared insulin lispro and regular human insulin in the mealtime treatment of 1,008 patients with IDDM. The study was a 6-month randomized multinational (17 countries) and multicenter (102 investigators) clinical trial performed with an open-label crossover design. Insulin lispro was injected immediately before the meal, and regular human insulin was injected 30-45 min before the meal. Throughout the study, the postprandial rise in serum glucose was significantly lower during insulin lispro therapy. At the endpoint, the postprandial rise in serum glucose was reduced at 1 h by 1.3 mmol/l and at 2 h by 2.0 mmol/l in patients treated with insulin lispro (P < 0.001). The rate of hypoglycemia was 12% less with insulin lispro (6.4 +/- 0.2 vs. 7.2 +/- 0.3 episodes/30 days, P < 0.001), independent of basal insulin regimen or HbA1c level. The reduction was observed equally in episodes with and without symptoms. When the total number of episodes for each patient was analyzed according to the time of occurrence, the number of hypoglycemic episodes was less with insulin lispro than with regular human insulin therapy during three of four quarters of the day (P < 0.001). The largest relative improvement was observed at night. In conclusion, insulin lispro improves postprandial control, reduces hypoglycemic episodes, and improves patient convenience, compared with regular human insulin, in IDDM patients.