Effects of acute exercise intensity on plasma lipids and apolipoproteins in trained runners.

The purpose of this study was to determine the effects of exercise intensity on lipid and lipoprotein metabolism. Concentrations of triglyceride, cholesterol, high-density lipoprotein cholesterol (HDL-C) and its subfractions (HDL2-C and HDL3-C), low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and apolipoproteins A-I, A-II, and B were measured. Ten well-trained runners completed treadmill exercise on two different occasions: a high-intensity session at 75% maximal oxygen consumption lasting 60 min and a low-intensity session at 50% maximal oxygen consumption lasting 90 min. Energy expenditure for each session was equal. Fasted blood samples were obtained 24 h before, immediately before, immediately after, and 1, 24, 48, and 72 h after each exercise session. No significant differences were found for the blood variables across time or between treatments. However, HDL-C and HDL2-C were slightly elevated on the days after each treatment. These results suggest that acute exercise sessions lasting less than 90 min, regardless of intensity, do not elicit plasma lipid, lipoprotein, and apolipoprotein changes in men who are habitually physically active and have high initial concentrations of HDL-C.     

Effects of depletion exercise and light training on muscle glycogen supercompensation in men

Supercompensated muscle glycogen can be achieved by using several carbohydrate (CHO)-loading protocols. This study compared the effectiveness of two "modified" CHO-loading protocols. Additionally, we determined the effect of light cycle training on muscle glycogen. Subjects completed a depletion (D, n = 15) or nondepletion (ND, n = 10) CHO-loading protocol. After a 2-day adaptation period in a metabolic ward, the D group performed a 120-min cycle exercise at 65% peak oxygen uptake (VO2 peak) followed by 1-min sprints at 120% VO2 peak to exhaustion. The ND group performed only 20-min cycle exercise at 65% VO2 peak. For the next 6 days, both groups ate the same high-CHO diets and performed 20-min daily cycle exercise at 65% VO2 peak followed by a CHO beverage (105 g of CHO). Muscle glycogen concentrations of the vastus lateralis were measured daily with 13C magnetic resonance spectroscopy. On the morning of day 5, muscle glycogen concentrations had increased 1.45 (D) and 1.24 (ND) times baseline (P < 0.001) but did not differ significantly between groups. However, on day 7, muscle glycogen of the D group was significantly greater (p < 0.01) than that of the ND group (130 +/- 7 vs. 104 +/- 5 mmol/l). Daily cycle exercise decreased muscle glycogen by 10 +/- 2 (D) and 14 +/- 5 mmol/l (ND), but muscle glycogen was equal to or greater than preexercise values 24 h later. In conclusion, a CHO-loading protocol that begins with a glycogen-depleting exercise results in significantly greater muscle glycogen that persists longer than a CHO-loading protocol using only an exercise taper. Daily exercise at 65% VO2 peak for 20 min can be performed throughout the CHO-loading protocol without negatively affecting muscle glycogen supercompensation.     

Effects of exercise training on thermoregulatory responses and blood volume in older men.

We assessed the effects of aerobic and/or resistance training on thermoregulatory responses in older men and analyzed the results in relation to the changes in peak oxygen consumption rate (VO(2 peak)) and blood volume (BV). Twenty-three older men [age, 64 +/- 1 (SE) yr; VO(2 peak), 32.7 +/- 1.1 ml. kg(-1). min(-1)] were divided into three training regimens for 18 wk: control (C; n = 7), aerobic training (AT; n = 8), and resistance training (RT; n = 8). Subjects in C were allowed to perform walking of ~10,000 steps/day, 6-7 days/wk. Subjects in AT exercised on a cycle ergometer at 50-80% VO(2 peak) for 60 min/day, 3 days/wk, in addition to the walking. Subjects in RT performed a resistance exercise, including knee extension and flexion at 60-80% of one repetition maximum, two to three sets of eight repetitions per day, 3 days/wk, in addition to the walking. After 18 wk of training, VO(2 peak) increased by 5.2 +/- 3.4% in C (P > 0.07), 20.0 +/- 2.5% in AT (P < 0.0001), and 9.7 +/- 5.1% in RT (P < 0.003), but BV remained unchanged in all trials. In addition, the esophageal temperature (T(es)) thresholds for forearm skin vasodilation and sweating, determined during 30-min exercise of 60% VO(2 peak) at 30 degrees C, decreased in AT (P < 0.02) and RT (P < 0.02) but not in C (P > 0.2). In contrast, the slopes of forearm skin vascular conductance/T(es) and sweat rate/T(es) remained unchanged in all trials, but both increased in subjects with increased BV irrespective of trials with significant correlations between the changes in the slopes and BV (P < 0.005 and P < 0.0005, respectively). Thus aerobic and/or resistance training in older men increased VO(2 peak) and lowered T(es) thresholds for forearm skin vasodilation and sweating but did not increase BV. Furthermore, the sensitivity of the increase in skin vasodilation and sweating at a given increase in T(es) was more associated with BV than with VO(2 peak).     

Training intensity, blood lipids, and apolipoproteins in men with high cholesterol

Crouse, Stephen F., Barbara C. O'Brien, Peter W. Grandjean,Robert C. Lowe, J. James Rohack, John S. Green, and Homer Tolson. Training intensity, blood lipids, and apolipoproteins in men withhigh cholesterol. J. Appl. Physiol.82(1): 270-277, 1997.Twenty-six hypercholesterolemic men (meancholesterol, 258 mg/dl; age, 47 yr; weight, 81.9 kg) completed 24 wk ofcycle ergometer training (3 days/wk, 350 kcal/session) at either high(n = 12) or moderate (n = 14) intensity (80 and 50%maximal O₂ uptake, respectively, randomly assigned) to test the influence of training intensity on bloodlipid and apolipoprotein (apo) concentrations. Allphysiological, lipid, and apo measurements were completed at 0, 8, 16, and 24 wk. Lipid data were analyzed via two × fourrepeated-measures analysis of variance ( = 0.0031). Trainingproduced a significant decrease in body weight and increase in maximalO₂ uptake. No interactions betweenintensity and weeks of training were noted for any lipid or apovariable, and no between-group differences were significant before orthroughout training. Therefore, intensity did not affect the trainingresponse. Regardless of intensity, apo AI and apo B fell 9 and 13%,respectively, by week 16 and remainedlower through week 24 (P < 0.0003). Total cholesterol felltransiently (5.5%) by week 16 (P < 0.0021) but returned to initiallevels by week 24. Triglyceride,low-density-lipoprotein cholesterol, and high-density-lipoprotein (HDL)cholesterol did not change with training. In contrast,HDL₂ cholesterol rose 79% aboveinitial levels by week 8 and 82%above initial levels by week 24 (P < 0.0018);HDL₃ cholesterol fell 8 and 13%over the same training intervals (P < 0.0026). These data show that changes in blood lipid and apoconcentrations that accompany training in hypercholesterolemic men arenot influenced by exercise intensity when caloric expenditure is heldconstant.

     

Effects of four different single exercise sessions on lipids, lipoproteins, and lipoprotein lipase

The purpose ofthis study was to determine the threshold of exercise energyexpenditure necessary to change blood lipid and lipoproteinconcentrations and lipoprotein lipase activity (LPLA) in healthy,trained men. On different days, 11 men (age, 26.7 ± 6.1 yr; bodyfat, 11.0 ± 1.5%) completed four separate, randomly assigned,submaximal treadmill sessions at 70% maximalO₂ consumption. During eachsession 800, 1,100, 1,300, or 1,500 kcal were expended. Compared withimmediately before exercise, high-density lipoprotein cholesterol(HDL-C) concentration was significantly elevated 24 h after exercise(P < 0.05) in the 1,100-, 1,300-, and 1,500-kcal sessions. HDL-C concentration was also elevated(P < 0.05) immediately after and 48 h after exercise in the 1,500-kcal session. Compared with values 24 hbefore exercise, LPLA wassignificantly greater (P < 0.05) 24 h after exercise in the 1,100-, 1,300-, and 1,500-kcal sessions andremained elevated 48 h after exercise in the 1,500-kcal session. Thesedata indicate that, in healthy, trained men, 1,100 kcal of energyexpenditure are necessary to elicit increased HDL-C concentrations.These HDL-C changes coincided with increased LPLA.

     

Short-term exercise training improves vascular function in hypercholesterolemic rabbit femoral artery

Chronic exercise in healthy or hypercholesteremic animals for at least two months improves their vascular functions. This study is to examine whether short-term exercise training protocols can correct early-stage vascular dysfunction induced by high-cholesterol diet feeding. Male New Zealand White rabbits were fed for 2, 4 or 6 weeks with rabbit chow with or without the addition of 2% (w/w) cholesterol. They were further divided into control and exercise groups. Animals in exercise groups ran on a leveled treadmill for the same time periods as diet intervention. At the end of experiments, femoral arteries were dissected, loaded with fura 2-AM, and mounted in a tissue flow chamber. Phenylephrine-precontracted vessel specimens were exposed to acetylcholine. The endothelial intracellular calcium elevation and vasorelaxation were determined simultaneously under an epifluorescence microscope with ratio imaging capability. En face oil red O staining was used to evaluate fatty streak formation. Our results showed that 1) high-cholesterol diet feeding for > or = 4 weeks caused lipid deposition, reduced the acetylcholine-evoked endothelial calcium signaling, and impaired both endothelium-dependent and endothelium-independent vascular responses in a time-dependent manner; 2) vasorelaxation at given levels of endothelial intracellular calcium elevation decreased in hypercholesterolemia; 3) concomitant exercise program had reverse effects. We conclude that high-cholesterol diet intervention for as short as 4 weeks induces vascular structural changes, impairs endothelial intracellular calcium signaling and vasodilatation in rabbit femoral arteries. Short-term exercise training in parallel completely eliminates these adverse effects so long as the diet intervention is no more than 6 weeks.     

Influence of exercise order in a resistance-training exercise session

The order of resistance exercises within a training session may have a vital impact on the quality of the constituent exercises performed. However, very few studies have documented the specific influence of exercise order. Therefore, the purpose of this study was to examine the effect of exercise order on back squat performance in the context of a whole-body workout. Nine resistance-trained male subjects (age: 24 +/- 4 years, body mass: 81.5 +/- 15.3 kg, resistance-training experience: 7 +/- 4 years) performed the back squat exercise (4 sets at 85% of 1 repetition maximum) on 2 separate occasions in a balanced, crossover design. During one protocol, the squat exercise was performed first (protocol A); during the other protocol, it was performed after a whole-body resistance-exercise session (protocol B). Number of repetitions, average power, and rating of perceived exertion (RPE) were collected during each set of the squat exercise. All subjects performed significantly (p < 0.01) more repetitions during set 1 when they performed protocol A (8.0 +/- 1.9 repetitions) compared with protocol B (5.4 +/- 2.7 repetitions). The average power for each set was higher during protocol B compared with protocol A. There were no significant differences in RPE values between the 2 protocols. In conclusion, performing the barbell back squat first in an exercise session allowed the completion of more total repetitions. However, this study showed that performing the squat exercise after a whole-body workout session may result in greater power output if the squat is preceded by a power exercise (i.e., hang pull). This phenomenon may have been due to postactivation potentiation.     

Effects of exercise training modality on skeletal muscle fatigue in men with coronary heart disease

Cardiopulmonary and skeletal muscle effects of combined aerobic and resistance training vs. aerobic training were studied in men with coronary heart disease. Sixteen men with coronary heart disease underwent a cardiopulmonary exercise testing and a quadriceps skeletal muscle fatigue assessment. Patients were divided into two groups and trained in a combined aerobic and resistance or aerobic training group during 7 weeks. Maximal voluntary contraction and isometric endurance time were measured with electromyographic signals recorded from vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM) during isometric endurance time. Exercise tolerance increased only in the combined group (p < 0.05). Maximal voluntary contraction and isometric endurance time did not change after training in either group but was performed at 5.8% higher force output for the combined group. After training, median frequency values were higher for the VL and VM (p < 0.001) in the aerobic group and also higher for the VL, RF (p < 0.001) and VM (p < 0.05) in the combined group. Combined aerobic and resistance training was more effective to improve exercise tolerance, decrease skeletal muscle fatigue and correct neuromuscular alterations in men with coronary heart disease.     

Synovial fluid lipids and apolipoproteins: a contemporary perspective

Normal human synovial fluid contains extremely low concentrations of lipoproteins and apolipoproteins, in sharp contrast to those found in plasma. Increased amounts of cholesterol and other lipids have been found in the synovial fluid of a chronic inflammatory joint disorder, rheumatoid arthritis (RA). More recently, apolipoproteins AI, B and E have also been found in increased amounts in RA synovial fluid. Theories have been proposed to account for this increase in the amount of apolipoproteins and for the source of lipids and lipoproteins in normal synovial fluid; however, the mechanisms have not yet been established. Lipoproteins may play dual roles in synovial fluid: A functional one in normal synovial fluid and, as some suggest, a pathologic one in the abnormal synovial fluid of certain arthritic diseases. The recent data prompt the need to define synovial fluid lipids, lipoprotein particle subfractions and their constituent apolipoproteins, as well as their respective roles in synovial fluid.     

Effects of creatine supplementation and exercise training on fitness in men 55-75 yr old.

effect of oral creatine supplementation (CR; 5 g/day) in conjunction with exercise training on physical fitness was investigated in men between 55 and 75 yr of age (n = 46). A double-blind randomized placebo-controlled (PL) trial was performed over a 6-mo period. Furthermore, a subgroup (n = 20) completed a 1-yr follow-up. The training program consisted of cardiorespiratory endurance training as well as moderate resistance training (2-3 sessions/wk). Endurance capacity was evaluated during a maximal incremental bicycle ergometer test, maximal isometric strength of the knee-extensor muscles was assessed by an isokinetic dynamometer, and body composition was assessed by hydrostatic weighing. Furthermore, in a subgroup (PL: n = 13; CR: n = 12) biopsies were taken from m. vastus lateralis to determine total creatine (TCr) content. In PL, 6 mo of training increased peak oxygen uptake rate (+16%; P < 0.05). Fat-free mass slightly increased (+0.3 kg; P < 0.05), whereas percent body fat slightly decreased (-1.2%; P < 0.05). The training intervention did not significantly change either maximal isometric strength or body weight. The responses were independent of CR. Still, compared with PL, TCr was increased by approximately 5% in CR, and this increase was closely correlated with initial muscle creatine content (r = -0.78; P < 0.05). After a 1-yr follow-up, muscle TCr was not higher in CR than in PL. Furthermore, the other measurements were not affected by CR. It is concluded that long-term creatine intake (5 g/day) in conjunction with exercise training does not beneficially impact physical fitness in men between 55 and 75 yr of age.     

Neutrophil fatty acid composition: effect of a single session of exercise and glutamine supplementation

The fatty acid composition of immune cells appears to contribute to variations of cell function. The independent and combined effects of a single session of exercise (SSE) and glutamine supplementation (GS) on neutrophil fatty acid composition were investigated. Compared to control (no treatment given--i.e. neither SSE or GS), single session of exercise decreased myristic, palmitic and eicosapentaenoic (EPA) acids, and increased lauric, oleic, linoleic, arachidonic (AA) and docosahexaenoic (DHA) acids whereas glutamine supplementation combined with SSE (GS+SSE) increased oleic acid. Polyunsaturated/saturated fatty acid ratio and Unsaturation index were higher in neutrophils from the SSE and GS groups as compared with control. These findings support the proposition that SSE and GS may modulate neutrophil function through alterations in fatty acid composition.     

Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men

We examined whether enhanced cardiovascular and thermoregulatory responses during exercise after short-term aerobic training in a warm environment were reversed when plasma volume (PV) expansion was reversed by acute isotonic hypohydration. Seven young men performed aerobic training at the 70% peak oxygen consumption rate (Vo(?peak)) at 30°C atmospheric temperature and 50% relative humidity, 30 min/day for 5 days. Before and after training, we performed the thermoregulatory response test while measuring esophageal temperature (T(es)), forearm skin vascular conductance, sweat rate (SR), and PV during 30 min exercise at the metabolic rate equivalent to pretraining 65% Vo(?peak) in euhydration under the same environment as during training in four trials (euhydration and hypohydration, respectively). Hypohydration targeting 3% body mass was attained by combined treatment with low-salt meals to subjects from ~48 h before the test and administration of a diuretic ~4 h before the test. After training, the T(es) thresholds for cutaneous vasodilation and sweating decreased by 0.3 and 0.2°C (P = 0.008 and 0.012, respectively) when PV increased by ~10%. When PV before and after training was reduced to a similar level, ~10% reduction from that in euhydration before training, the training-induced reduction in the threshold for cutaneous vasodilation increased to a level similar to hypohydration before training (P = 0.093) while that for sweating remained significantly lower than that before training (P = 0.004). Thus the enhanced cutaneous vasodilation response after aerobic training in a warm environment was reversed when PV expansion was reversed while the enhanced SR response remained partially.     

The acute effects of a single set of contrast preloading on a loaded countermovement jump training session

The aim of this research was to assess the effect of a single set of contrast preloading on peak vertical displacement (PD) during a loaded countermovement jump (LCMJ) training session. Nine strength-trained males participated in 2 randomly assigned, crossover design testing sessions consisting of 5 sets of 6 repetitions of 20-kg LCMJs with 3-minute rest intervals between sets. The preloading intervention was performed 3 minutes after the first set and 4 minutes before the second set of 20-kg LCMJs. The control (CON) group performed 1 set of 20-kg LCMJs, whereas the jump squat (JS) group performed 1 set of 40-kg LCMJs. The number of repetitions performed during each preloading condition was varied to match total concentric work between the 2 sessions. A significant (p < 0.05) preload x set interaction for PD was observed, with the JS group jumping significantly higher during the third set performed after the preload in comparison with the CON group. Analysis of peak power output and mean power output during the concentric movement for this set revealed that as the knee flexion angle increased, the effect of the preload was augmented. These results suggest that a single set of preloading exercises enhances performance during a lower-body explosive power training session; however, the effects of a single preloading set may not peak until midway through the training session.     

Determination of urine steroid profile in untrained men to evaluate recovery after a strength training session

Intense physical exercise is an important modifier of hormone metabolism. The aim of this study was to evaluate the variations in the urine profile of glucuroconjugated steroids (androgens, estrogens, and corticosteroids) as a consequence of a session of strength exercises. The subjects were a group (N = 20) of untrained male university students. They performed 3 sets of 10 repetitions, with a 3-minute recovery time between sets, at 70-75% of 1 repetition maximum (1RM). Four urine samples were collected per subject: before the session, immediately after, 3 hours after, and 48 hours after the session. They were assayed using a gas chromatograph coupled with a mass spectrometer. The concentrations of the different hormones were determined according to the urine creatinine level (ng steroid per mg creatinine). The substances assayed were testosterone, epitestosterone (Epit), androstenedione, dehydroepiandrosterone (DHEA), androsterone, etiocholanolone, beta-estradiol, estrone, tetrahydrocortisone (THE), and tetrahydrocortisol (THF). The results showed a significant decline after exercise with respect to the rested state in the urinary excretion of testosterone, Epit, DHEA, androsterone, and etiocholanolone. At 48 hours, there was a significant increase in the urinary excretion of Epit, androstenedione, androsterone, etiocholanolone, estrone, and THE. The androsterone + etiocholanolone/THE + THF ratio decreased after exercise, increased significantly (p < 0.05) at 3 hours, and returned to near resting levels at 48 hours. The data suggest that the performing a strength session at 70-75% of maximum strength provoked a state of fatigue in the subjects, from which they recovered 48 hours after the exercise.     

Endurance training increases gluconeogenesis during rest and exercise in men

Plasma albumin is well known to decrease in response to inflammation. The rate of albumin synthesis from both liver and plasma was measured in vivo by use of a large dose of L-[(2)H(3)-(14)C]valine in rats injected intravenously with live Escherichia coli and in pair-fed control rats during the acute-phase period (2 days postinfection). The plasma albumin concentration was reduced by 50% in infected rats compared with pair-fed animals. Infection induced a fall in both liver albumin mRNA levels and albumin synthesis relative to total liver protein synthesis. However, absolute liver albumin synthesis rate (ASR) was not affected by infection. In plasma, albumin fractional synthesis rate was increased by 50% in infected animals compared with pair-fed animals. The albumin ASR estimated in the plasma was similar in the two groups. These results suggest that hypoalbuminemia is not due to reduced albumin synthesis during sepsis. Moreover, liver and plasma albumin ASR were similar. Therefore, albumin synthesis measured in the plasma is a good indicator of liver albumin synthesis.     

Aerobic exercise training reduces epicardial fat in obese men

The purpose of this study was to determine the effects of exercise training on ventricular epicardial fat thickness in obese men and to investigate the relationship of the change in epicardial fat thickness to changes in abdominal fat tissue following exercise training. Twenty-four obese middle-aged men [age, 49.4 +/- 9.6 yr; weight, 87.7 +/- 11.2 kg; body mass index (BMI), 30.7 +/- 3.3 kg/m(2); peak oxygen consumption, 28.4 +/- 7.2 ml.kg(-1).min(-1); means +/- SD] participated in this study. Each participant completed a 12-wk supervised exercise training program (60-70% of the maximal heart rate; 60 min/day, 3 days/wk) and underwent a transthoracic echocardiography. The epicardial fat thickness on the free wall of the right ventricle was measured from both parasternal long- and short-axis views. The visceral adipose tissue (VAT) and subcutaneous adipose tissues were measured by computed tomography. Following exercise training, the epicardial fat thickness was significantly decreased (P < 0.001). The percentage change of epicardial fat thickness was twice as high compared with those of waist, BMI, and body weight of original values (P <0.05). There was a significant relationship (r = 0.525, P = 0.008) between changes in the epicardial fat thickness and VAT with exercise training. Stepwise multiple regression analysis revealed that the change in VAT, change in systolic blood pressure, and change in quantitative insulin sensitivity check index were independently related to the change epicardial fat thickness (P < 0.05). The ventricular epicardial fat thickness is reduced significantly after aerobic exercise training and is associated with a decrease in VAT. These results suggest that aerobic exercise training may be an effective nonpharmacological strategy for decreasing the ventricular epicardial fat thickness and visceral fat area in obese middle-aged men.