Maximal vascular leg conductance in trained and untrained men

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.     

Metabolic changes following eccentric exercise in trained and untrained men

The effects of one 45-min bout of high-intensity eccentric exercise (250 W) were studied in four male runners and five untrained men. Plasma creatine kinase (CK) activity in these runners was higher (P less than 0.001) than in the untrained men before exercise and peaked at 207 IU/ml 1 day after exercise, whereas in untrained men the maximum was 2,143 IU/ml 5 days after exercise. Plasma interleukin-1 (IL-1) in the trained men was also higher (P less than 0.001) than in the untrained men before exercise but did not significantly increase after exercise. In the untrained men, IL-1 was significantly elevated 3 h after exercise (P less than 0.001). In the untrained group only, 24-h urines were collected before and after exercise while the men consumed a meat-free diet. Urinary 3-methylhistidine/creatinine in the untrained group rose significantly from 127 mumol/g before exercise to 180 mumol/g 10 days after exercise. The results suggest that in untrained men eccentric exercise leads to a metabolic response indicative of delayed muscle damage. Regularly performed long distance running was associated with chronically elevated plasma IL-1 levels and serum CK activities without acute increases after an eccentric exercise bout.     

Cardiovascular response to static handgrip in trained and untrained men

The influence of aerobic capacity on the cardiovascular response to handgrip exercise, in relation to the muscle mass involved in the effort, was tested in 8 trained men (T) and 17 untrained men (U). The subjects performed handgrip exercises with the right-hand (RH), left-hand (LH) and both hands simultaneously (RLH) at an intensity of 25% of maximal voluntary contraction force. Maximal aerobic capacity was 4.3 l.min-1 in T and 3.21 l.min-1 in U (P less than 0.01). The endurance time for handgrip was longer in T than in U by 29% (P less than 0.05) for RH, 38% (P less than 0.001) for LH and 24% (P less than 0.001) for RLH. Heart rate (fc) was significantly lower in T than in U before handgrip exercise, and showed smaller increases (P less than 0.01) at the point of exhaustion: 89 vs 106 beats.min-1 for RH, 93 vs 100 beats.min-1 for LH and 92 vs 108 beats.min-1 for RLH. Stroke volume (SV) at rest was greater in T than in U and decreased significantly (P less than 0.05) during handgrip exercise in both groups of subjects. At the point of exhaustion SV was still greater in T than in U: 75 vs 57 ml for RH, 76 vs 54 ml for LH and 76 vs 56 ml for RLH. During the last seconds of handgrip exercise, the left ventricular ejection time was longer in T than in U. Increases in cardiac output (Qc) and systolic blood pressure did not differ substantially between T and U, nor between the handgrip exercise tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of beta-blockade on exercise capacity of trained and untrained men: a hemodynamic comparison

To study the effects of cardiovascular fitness on hemodynamic responses to exercise during beta-adrenergic blockade (BAB), submaximal [60% of maximum O2 uptake (VO2max)] and maximal treadmill exercise data were collected in 11 trained (T, VO2max 63.3 ml X kg-1 X min-1, 26.8 yr) and 11 untrained (UT, VO2max 44.5 ml X kg-1 X min-1, 25.0 yr) male subjects. Subjects completed two maximal control tests followed by a randomized, double-blind series of maximal tests after 1-wk treatments with placebo (PLAC), propranolol (PROP, 160 mg/day, beta 1- and beta 2-blockade), and atenolol (ATEN, 100 mg/day, beta 1-blockade). Treatments were separated by 1-wk washout periods. At 60% of control VO2max T and UT subjects experienced no reductions in O2 uptake (VO2) with either drug. Submaximal heart rate (HR, beats/min) was 134.8 PLAC, 107.0 PROP, 107.9 ATEN (P less than 0.05 both drugs vs. PLAC) in T subjects and 141.1 PLAC, 106.1 PROP, and 105.0 ATEN (P less than 0.05 both drugs vs. PLAC) in UT subjects. Cardiac output (1/min) for T was 17.3 PLAC, 16.9 PROP, 16.5 ATEN (P less than 0.05 ATEN vs. PLAC in T only) and for UT it was 12.2 (PLAC), 11.7 (PROP), 11.5 (ATEN) (P less than 0.05 both drugs vs. PLAC in UT). Stroke volume increased from 129.8 ml (PLAC) to 158.6 (PROP) and 156.2 (ATEN) in T (P less than 0.05 both drugs vs. PLAC) and from 86.8 (PLAC) to 110.0 (PROP) and 109.8 (ATEN) (P less than 0.05 both drugs vs. PLAC) in UT. The increases in stroke volume (SV) were similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potassium and ventilation during incremental exercise in trained and untrained men.

The present investigation was undertaken to examine the relationship between plasma potassium (K+) and ventilation (VE) during incremental exercise. Blood lactate (La-) was also measured, and its relationship with VE was similarly examined. Eight endurance-trained triathletes (ET) and eight active but untrained men (UT) performed an incremental cycling test to volitional fatigue. Maximal oxygen uptake (VO2max) and oxygen uptake (VO2) at lactate threshold (LT) were higher (P < 0.05) in ET (VO2max 4.60 +/- 0.10 l/min, LT 2.77 +/- 0.85 l/min) than in UT (VO2max 3.79 +/- 0.11 l/min, LT 1.94 +/- 0.60 l/min). There were significant (P < 0.05) correlations between VE and K+ (UT 0.87, ET 0.77) and between VE and La- (UT 0.88, ET 0.85). In ET compared with UT, VE was lower (P < 0.05) at 330 W, K+ was lower at 300 and 330 W, and La- was lower at all work loads > 90 W. These results suggest that K+ may make an important contribution to the regulation of ventilation during incremental exercise and that endurance training attenuates the K+ response to that exercise.     

Exercise intensity: effect on postexercise O2 uptake in trained and untrained women

Despite many reports of long-lasting elevation of metabolism after exercise, little is known regarding the effects of exercise intensity and duration on this phenomenon. This study examined the effect of a constant duration (30 min) of cycle ergometer exercise at varied intensity levels [50 and 70% of maximal O2 consumption (VO2max)] on 3-h recovery of oxygen uptake (VO2). VO2 and respiratory exchange ratios were measured by open-circuit spirometry in five trained female cyclists (age 25 +/- 1.7 yr) and five untrained females (age 27 +/- 0.8 yr). Postexercise VO2 measured at intervals for 3 h after exercise was greater (P less than 0.01) after exercise at 50% VO2max in trained (0.40 +/- 0.01 l/min) and untrained subjects (0.39 +/- 0.01 l/min) than after 70% VO2max in (0.31 +/- 0.02 l/min) and untrained subjects (0.29 +/- 0.02 l/min). The lower respiratory exchange ratio values (P less than 0.01) after 50% VO2max in trained (0.78 +/- 0.01) and untrained subjects (0.80 +/- 0.01) compared with 70% VO2max in trained (0.81 +/- 0.01) and untrained subjects (0.83 +/- 0.01) suggest that an increase in fat metabolism may be implicated in the long-term elevation of metabolism after exercise. This was supported by the greater estimated fatty acid oxidation (P less than 0.05) after 50% VO2max in trained (147 +/- 4 mg/min) and untrained subjects (133 +/- 9 mg/min) compared with 70% VO2max in trained (101 +/- 6 mg/min) and untrained subjects (85 +/- 7 mg/min).     

Hormonal responses to resistance exercise in long-term trained and untrained middle-aged men

This cross-sectional study compared hormonal responses to resistance exercise between trained and untrained men to investigate the adaptations of the endocrine system to long-term strength training in middle-aged men. Twenty-one middle-aged men were recruited for this study and matched into a strength-trained group (SG) (n = 10) and an untrained group (UG) (n = 11). In the SG, the individuals had practiced strength training for hypertrophy for at least 3 years. Upper- and lower-body muscle strength was measured with a 1 repetition maximum (1RM) test. Blood samples were collected at rest and after multiple sets of a superset strength training protocol (SSTP), with an intensity of 75% of 1RM values. With these blood samples, the levels of total testosterone (TT), free testosterone (FT), dehydroepiandrosterone (DHEA), cortisol, and sex hormone-binding globulin (SHBG) were determined. In addition, the TT-to-cortisol ratio and TT-to-SHBG ratio were calculated. There was no difference at rest between groups in hormonal values for TT, FT, DHEA, cortisol, the TT-to-SHBG ratio, and the TT-to-cortisol ratio. There were increases after SSTP in the levels of TT, FT, DHEA, and cortisol and the TT-to-SHBG ratio in the UG, but only FT increased in the SG. The SG demonstrated lower values in the TT-to-SHBG ratio after the training session. These results suggest the presence of alterations in anabolic and catabolic hormonal responses to resistance exercise in long-term trained middle-aged men, with the trained subjects demonstrating lower responsiveness in the hormone values. Long-term trained men seem to require a higher volume of training, at least similar to their daily workout, to stimulate greater hormone responses.     

Beta-blockade reduces tidal volume during heavy exercise in trained and untrained men

The effects of beta-blockade on tidal volume (VT), breath cycle timing, and respiratory drive were evaluated in 14 endurance-trained [maximum O2 uptake (VO2max) approximately 65 ml X kg-1 X min-1] and 14 untrained (VO2max approximately 50 ml X kg-1 X min-1) male subjects at 45, 60, and 75% of unblocked VO2max and at VO2max. Propranolol (PROP, 80 mg twice daily), atenolol (ATEN, 100 mg once a day) and placebo (PLAC) were administered in a randomized double-blind design. In both subject groups both drugs attenuated the increases in VT associated with increasing work rate. CO2 production (VCO2) was not changed by either drug during submaximal exercise but was reduced in both subject groups by both drugs during maximal exercise. The relationship between minute ventilation (VE) and VCO2 was unaltered by either drug in both subject groups due to increases in breathing frequency. In trained subjects VT was reduced during maximal exercise from 2.58 l/breath on PLAC to 2.21 l/breath on PROP and to 2.44 l/breath on ATEN. In untrained subjects VT at maximal exercise was reduced from 2.30 l/breath on PLAC to 1.99 on PROP and 2.12 on ATEN. These observations indicate that 1) since VE vs. VCO2 was not altered by beta-adrenergic blockade, the changes in VT and f did not result from a general blunting of the ventilatory response to exercise during beta-adrenergic blockade; and 2) blockade of beta 1- and beta 2-receptors with PROP caused larger reductions in VT compared with blockade of beta 1-receptors only (ATEN), suggesting that beta 2-mediated bronchodilation plays a role in the VT response to heavy exercise.     

Effect of warm-up on the standing broad jump in trained and untrained men and women

The effect of 3 warm-up routines on standing broad jump (SBJ) performance was investigated. Thirty-two men and women participated as subjects. Following the determination of 1-repetition maximum (1RM) squat, subjects completed warm-up routines and broad jumps on 4 occasions in a randomized order. Subjects performed SBJ immediately (POST) and 15 min following (POST15) the given warm-up routine. The routines were high force, consisting of high % 1RM, low repetition squats; high power, consisting of low % 1RM, low repetition speed squats; stretching, consisting of static stretches; and no activity, a control condition. Repeated measures analysis of covariance (ANCOVA) revealed no differences among broad jump performance following any of the warm-up routines (p = 0.157). A strong correlation (R = 0.805) was found between 1RM squat and SBJ. These data indicate that warm-up of any type has little effect on jump performance and that maximum strength is strongly related to jumping ability.     

Capillary density and capillary-to-fibre ratio in vastus lateralis muscle of untrained and trained men

Muscle fibre profile area (Af), volume density (Vv), capillary-to-fibre ratio (CF) and number of capillaries per fibre square millimetre (CD) were determined from needle biopsies of vastus lateralis of twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg) of different training background. Seven subjects were untrained students (group A), nine were national and sub-national level endurance athletes (group B) with the background of 7.8+/-2.9 years of specialised training, and eight subjects were sprint-power athletes (group C) with 12.8+/-8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase. Capillaries were visualized and counted using CD31 antibodies against endothelial cells. There were significant differences in the Vv of type I and type II muscle fibres in both trained groups, B (51.8%; 25.6%) and C (50.5%; 26.4%). However, in untrained group A that was treated as a reference group, the difference between Vv of type I and type II fibres was less prominent, nevertheless statistically significant (42.1%; 35.1%). There was also a significant difference in CF: 1.9 in group A and 2.1 in groups B and C. The number of capillaries per mm2 (CD) was 245 (group A), 308 (group B) and 325 (group C). Significant differences (P<0.05) in CF and CD, were found only between group A (1.9; 245) and both groups of trained men, B and C (2.1; 308 and 325). However, endurance athletes (group B), such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C) such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance.     

Respiratory gas-exchange ratios during graded exercise in fed and fasted trained and untrained men

We evaluated the hypotheses that endurance training increasesrelative lipid oxidation over a wide range of relative exercise intensities in fed and fasted states and that carbohydrate nutrition causes carbohydrate-derived fuels to predominate as energy sources during exercise. Pulmonary respiratory gas-exchange ratios [(RER) = CO₂production/O₂ consumption(O₂)] were determinedduring four relative, graded exercise intensities in both fed andfasted states. Seven untrained (UT) men and seven category 2 and 3 US Cycling Federation cyclists (T) exercised in the morning in random order, with target power outputs of 20 and 40% peakO₂(O_{2 peak}) for 2 h,60% O_{2 peak} for 1.5 h, and 80%O_{2 peak} fora minimum of 30 min after either a 12-h overnight fast or 3 h after astandardized breakfast. Actual metabolic responses were 22 ± 0.33, 40 ± 0.31, 59 ± 0.32, and 75 ± 0.39%O_{2 peak}. T subjectsshowed significantly (P < 0.05)decreased RER compared with UT subjects at absolute workloads when fedand fasted. Fasting significantly decreased RER values compared withthe fed state at 22, 40, and 59%O_{2 peak} inT and at 40 and 59%O_{2 peak} in UTsubjects. Training decreased (P < 0.05) mean RER values compared with UT subjects at 22%O_{2 peak} when theyfasted, and at 40%O_{2 peak} when fed orfasted, but not at higher relative exercise intensities in eithernutritional state. Our results support the hypothesis that endurancetraining enhances lipid oxidation in men after a 12-h overnight fast at low relative exercise intensities (22 and 40%O_{2 peak}). However, atraining effect on RER was not apparent at high relative exercise intensities (59 and 75%O_{2 peak}). Becausemost athletes train and compete at exercise intensities >40% maximalO₂, they will not oxidize agreater proportion of lipids compared with untrained subjects,regardless of nutritional state.     

Cardiovascular responses to lower body negative pressure in trained and untrained older men.

To determine whether aerobic conditioning alters the orthostatic responses of older subjects, cardiovascular performance was monitored during graded lower body negative pressure in nine highly trained male senior athletes (A) aged 59-73 yr [maximum O2 uptake (VO2 max) = 52.4 +/- 1.7 ml.kg-1 x min-1] and nine age-matched control subjects (C) (VO2 max = 31.0 +/- 2.9 ml.kg-1 x min-1). Cardiac volumes were determined from gated blood pool scintigrams by use of 99mTc-labeled erythrocytes. During lower body negative pressure (0 to -50 mmHg), left ventricular end-diastolic and end-systolic volume indexes and stroke volume index decreased in both groups while heart rate increased. The decreases in cardiac volumes and mean arterial pressure and the increase in heart rate between 0 and -50 mmHg were significantly less in A than in C. For example, end-diastolic volume index decreased by 32 +/- 4 ml in C vs. 14 +/- 2 ml in A (P < 0.01), mean arterial pressure declined 7 +/- 5 mmHg in C and increased by 5 +/- 3 mmHg in A (P < 0.05), and heart rate increased 13 +/- 3 beats/min in C and 7 +/- 1 beats/min in A (P < 0.05). These data suggest that increased VO2 max among older men is associated with improved orthostatic responses.     

Influence of diet on the storage, mobilization and utilization of energy reserves in trained and untrained rats

The effect of the major dietary energy source (fat or carbohydrate) on some of the adaptations to physical training, particularly body composition and tissue glycogen concentrations, were studied in growing male Wistar rats. Resting liver glycogen concentrations were lower in both trained and sedentary rats fed a high fat diet compared to corresponding rats fed a high carbohydrate (low fat) diet. Trained rats on both diets had higher liver glycogen levels than corresponding sedentary controls. Resting gastrocnemius muscle glycogen concentrations were not influenced by diet or training. Rates of liver and muscle glycogen depletion during a 60-min swim were lower in trained rats but were not influenced by diet. Significant interactions were noted between the dietary energy source and exercise training with respect to body weight gain, body fat content, liver weight and liver glycogen concentrations.     

Left ventricular diastolic filling and systolic function of young and older trained and untrained men.

Aging is associated with impaired early diastolic filling; however, the effect of endurance training on resting diastolic function in older subjects is unclear. Heart rate and ventricular loading conditions affect mitral inflow velocities measured by Doppler echocardiography; therefore, tissue Doppler imaging of mitral annular velocity, which is relatively preload independent, was combined with mitral inflow velocity and maximal oxygen consumption (V(o2 max)) in young (20-35 yr) and older (60-80 yr) trained and untrained men to determine whether endurance training is associated with an attenuation of age-associated changes in diastolic filling. As expected, V(o2 max) was higher in trained men (P < 0.01) and lower in older men (P < 0.01). Peak early mitral inflow velocity (E) and early-to-late mitral inflow velocity ratios were lower in older vs. young men (P < 0.01); however, there was no training effect (P > 0.05). Peak early mitral annular velocity (E') was higher and peak late mitral annular velocity (A') was lower in young vs. older men (P < 0.01). A significant interaction effect was found for A', E'/A', and peak systolic mitral annular velocity (S'). Training was associated with lower A' in young and higher A' in older men. S' was greater in trained vs. untrained older men (P < 0.05), but it was similar in trained and untrained young men. These findings suggest that early diastolic filling is not affected by training in older men, and the effect of training on A' and S' is different in young and older men.     

Transfer effects in endurance exercise. Adaptations in trained and untrained muscles

The effects of 8 weeks of bicycle endurance training (5 X /week for 30 min) on maximal oxygen uptake capacity (VO2max) during arm and leg ergometry, and on the ultrastructure of an untrained arm muscle (m. deltoideus), and a trained leg muscle (m. vastus lateralis) were studied. With the training, leg-VO2max for bicycling increased by +13%, while the capillary per fiber ratio and the volume density of mitochondria in m. vastus lateralis increased by +15% and +40%, respectively. In contrast, the untrained m. deltoideus showed an unchanged capillary per fiber ratio and a decreased mitochondrial volume density (-17%). Despite this decrease of mitochondrial volume arm-VO2max increased by +9%. It seems unlikely that the observed discrepancy can be explained by cardiovascular adaptations, since arm cranking did not fully tax the cardiovascular system (arm-VO2max/leg-VO2max: 0.74 and 0.71 before and after training, respectively). Thus neither cardiovascular adaptations nor local structural changes in the untrained muscles could explain the increased arm-VO2max. However, the enhanced capacity for lactate clearance after endurance training could be sufficient to account for the larger VO2max during arm cranking. We propose that an increased net oxidation of lactate might be responsible for the increased arm-VO2max found after bicycle endurance training.