Enhanced endothelial vasoreactivity in endurance-trained older men.
(25/816)
Using external vascular ultrasound, we measured brachial artery diameter (Diam) at rest, after release of 4 min of limb ischemia, i. e., endothelium-dependent dilation (EDD), and after sublingual nitroglycerin, i.e., non-endothelium-dependent dilation (NonEDD), in 35 healthy men aged 61-83 yr: 12 endurance athletes (A) and 23 controls (C). As anticipated, treadmill exercise maximal oxygen consumption (VO(2 max)) was significantly higher in A than in C (40. 2 +/- 6.6 vs. 27.9 +/- 3.8 ml. kg(-1). min(-1); respectively, P < 0. 0001). With regard to arterial physiology, A had greater EDD (8.9 +/- 4.2 vs. 5.7 +/- 3.5%; P = 0.02) and a tendency for higher NonEDD (13.9 +/- 6.7 vs. 9.7 +/- 4.2%; P = 0.07) compared with C. By multiple linear regression analysis in the combined sample of older men, only baseline Diam (beta = -2.0, where beta is the regression coefficient; P = 0.005) and VO(2 max) (beta = 0.23; P = 0.003) were independent predictors of EDD; similarly, only Diam (beta = -4.0; P = 0.003) and VO(2 max) (beta = 0.27; P = 0.01) predicted NonEDD. Thus endurance-trained older men demonstrate both augmented EDD and NonEDD, consistent with a generalized enhanced vasodilator responsiveness, compared with their sedentary age peers. (+info)
Effect of oral DHEA on serum testosterone and adaptations to resistance training in young men.
(26/816)
This study examined the effects of acute dehydroepiandrosterone (DHEA) ingestion on serum steroid hormones and the effect of chronic DHEA intake on the adaptations to resistance training. In 10 young men (23 +/- 4 yr old), ingestion of 50 mg of DHEA increased serum androstenedione concentrations 150% within 60 min (P < 0.05) but did not affect serum testosterone and estrogen concentrations. An additional 19 men (23 +/- 1 yr old) participated in an 8-wk whole body resistance-training program and ingested DHEA (150 mg/day, n = 9) or placebo (n = 10) during weeks 1, 2, 4, 5, 7, and 8. Serum androstenedione concentrations were significantly (P < 0.05) increased in the DHEA-treated group after 2 and 5 wk. Serum concentrations of free and total testosterone, estrone, estradiol, estriol, lipids, and liver transaminases were unaffected by supplementation and training, while strength and lean body mass increased significantly and similarly (P < 0.05) in the men treated with placebo and DHEA. These results suggest that DHEA ingestion does not enhance serum testosterone concentrations or adaptations associated with resistance training in young men. (+info)
The athlete's heart. A meta-analysis of cardiac structure and function.
(27/816)
BACKGROUND: It has been postulated that depending on the type of exercise performed, 2 different morphological forms of athlete's heart may be distinguished: a strength-trained heart and an endurance-trained heart. Individual studies have not tested this hypothesis satisfactorily. METHODS AND RESULTS: The hypothesis of divergent cardiac adaptations in endurance-trained and strength-trained athletes was tested by applying meta-analytical techniques with the assumption of a random study effects model incorporating all published echocardiographic data on structure and function of male athletes engaged in purely dynamic (running) or static (weight lifting, power lifting, bodybuilding, throwing, wrestling) sports and combined dynamic and static sports (cycling and rowing). The analysis encompassed 59 studies and 1451 athletes. The overall mean relative left ventricular wall thickness of control subjects (0.36 mm) was significantly smaller than that of endurance-trained athletes (0.39 mm, P=0.001), combined endurance- and strength-trained athletes (0.40 mm, P=0.001), or strength-trained athletes (0.44 mm, P<0.001). There was a significant difference between the 3 groups of athletes and control subjects with respect to left ventricular internal diameter (P<0. 001), posterior wall thickness (P<0.001), and interventricular septum thickness (P<0.001). In addition, endurance-trained athletes and strength-trained athletes differed significantly with respect to mean relative wall thickness (0.39 versus 0.44, P=0.006) and interventricular septum thickness (10.5 versus 11.8 mm, P=0.005) and showed a trend toward a difference with respect to posterior wall thickness (10.3 versus 11.0 mm, P=0.078) and left ventricular internal diameter (53.7 versus 52.1 mm, P=0.055). With respect to cardiac function, there were no significant differences between athletes and control subjects in left ventricular ejection fraction, fractional shortening, and E/A ratio. CONCLUSIONS: Results of this meta-analysis regarding athlete's heart confirm the hypothesis of divergent cardiac adaptations in dynamic and static sports. Overall, athlete's heart demonstrated normal systolic and diastolic cardiac functions. (+info)
Changes in physical characteristics and performance of elite sailors following introduction of a sport science programme prior to the 1996 olympic games.
(28/816)
The objective of this study was to examine changes in sailors' physical characteristics during three different time periods immediately before the 1996 New Zealand Olympic trials, as a result of a newly introduced sport science programme. Twenty five (19 male and 6 female) Olympic development squad members volunteered as subjects and completed fitness tests at different times between April 1995 and March 1996 after being administered with individualised physical training programmes. Statistically significant improvements were observed in body weight, sum of skinfolds, flexibility (assessed using a sit-reach test), aerobic endurance (assessed using a maximal effort 2500 m rowing test) and strength (assessed as the maximum number of push-ups, pull-ups, and sit-ups that could be completed in 2 minutes) over the three time periods. Thus, physical training was effective in improving many aspects of sailors' fitness, especially early in the sailing season as a result of pre-season training. Physical performance correlated poorly with both light and heavy wind racing performance. The results suggest that individually tailored training programmes will increase sailing specific fitness. However, it is impossible to know what proportions of racing performance can be attributed to physical fitness, skill, talent, and technology, therefore the effect of physical training on racing performance is difficult to determine. (+info)
Effects of one year of resistance training on the relation between muscular strength and bone density in elderly women.
(29/816)
OBJECTIVES: There is a paucity of long term studies on exercise training in elderly women. The purpose of this study was to investigate the effects of one year of progressive resistance exercise (PRE) on dynamic muscular strength and the relations to bone mineral density (BMD) in elderly women. METHODS: Forty four healthy sedentary women (mean age 68.8 years) volunteered for this study and were randomly assigned to either an exercise group or a control group. The exercise group were involved in three one hour sessions a week for 52 weeks of supervised PRE to strengthen the large muscle groups of the body, while the control group were instructed to continue their normal lifestyle. The exercise circuit included three sets of eight repetitions at 75% of one repetition maximum focused on the large muscle groups. BMD was measured by dual energy x ray absoptiometry (Lunar DPX) at the lumbar spine and at three sites in the proximal femur. Other selected parameters of physical fitness were also measured. RESULTS: Statistical analyses (analysis of covariance) showed significant strength gains (p < 0.01) in bilateral bench press (> 29%), bilateral leg press (> 19%), and unilateral biceps curl (> 20%). No significant difference between groups was evident in body weight, grip strength, flexibility, waist to hip ratio, or the sum of eight skinfolds. Significant relations (p < 0.05) were recorded between dynamic leg strength and the BMD of the femoral neck, Ward's triangle, and the lumbar spine. CONCLUSIONS: Significant strength changes, after one year of PRE, were evident in elderly women, and the muscle increases may parallel changes in BMD; however, correlation coefficients were moderate. (+info)
Sensitivity of CPT I to malonyl-CoA in trained and untrained human skeletal muscle.
(30/816)
The present study examined the sensitivity of carnitine palmitoyltransferase I (CPT I) activity to its inhibitor malonyl-CoA (M-CoA), and simulated metabolic conditions of rest and exercise, in aerobically trained and untrained humans. Maximal CPT I activity was measured in mitochondria isolated from resting human skeletal muscle. Mean CPT I activity was 492.8 +/- 72.8 and 260.8 +/- 33.6 micromol. min(-1). kg wet muscle(-1) in trained and untrained subjects, respectively (pH 7.0, 37 degrees C). The sensitivity to M-CoA was greater in trained muscle; the IC(50) for M-CoA was 0.17 +/- 0.04 and 0.49 +/- 0.17 microM in trained and untrained muscle, respectively. The presence of acetyl-CoA, free coenzyme A (CoASH), and acetylcarnitine, in concentrations simulating rest and exercise conditions did not release the M-CoA-induced inhibition of CPT I activity. However, CPT I activity was reduced at pH 6.8 vs. pH 7.0 in both trained and untrained muscle in the presence of physiological concentrations of M-CoA. The results of this study indicate that aerobic training is associated with an increase in the sensitivity of CPT I to M-CoA. Accumulations of acetyl-CoA, CoASH, and acetylcarnitine do not counteract the M-CoA-induced inhibition of CPT I activity. However, small decreases in pH produce large reductions in the activity of CPT I and may contribute to the decrease in fat metabolism that occurs during moderate and intense aerobic exercise intensities. (+info)
Neural substrate for the effects of passive training on sensorimotor cortical representation: a study with functional magnetic resonance imaging in healthy subjects.
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Repetitive passive movements are part of most rehabilitation procedures, especially in patients with stroke and motor deficit. However, little is known about the consequences of repeated proprioceptive stimulations on the intracerebral sensorimotor network in humans. Twelve healthy subjects were enrolled, and all underwent two functional magnetic resonance imaging (fMRI) sessions separated by a 1-month interval. Passive daily movement training was performed in six subjects during the time between the two fMRI sessions. The other six subjects had no training and were considered as the control group. The task used during fMRI was calibrated repetitive passive flexion-extension of the wrist similar to those performed during training. The control task was rest. The data were analyzed with SPM96 software. Images were realigned, smoothed, and put into Talairach's neuroanatomical space. The time effect from the repetition of the task was assessed in the control group by comparing activation versus rest in the second session with activation versus rest in the first session. This time effect then was used as null hypothesis to assess the training effect alone in our trained group. Passive movements compared with rest showed activation of most of the cortical areas involved in motor control (i.e., contralateral primary sensorimotor cortex, supplementary motor area [SMA], cingulum, Brodmann area 40, ipsilateral cerebellum). Time effect comparison showed a decreased activity of the primary sensorimotor cortex and SMA and an increased activity of ipsilateral cerebellar hemisphere, compatible with a habituation effect. Training brought about an increased activity of contralateral primary sensorimotor cortex and SMA. A redistribution of SMA activity was observed. The authors demonstrated that passive training with repeated proprioceptive stimulation induces a reorganization of sensorimotor representation in healthy subjects. These changes take place in cortical areas involved in motor preparation and motor execution and represent the neural basis of proprioceptive training, which might benefit patients undergoing rehabilitative procedures. (+info)
Combined aerobic and resistance exercise training improves functional capacity and strength in CHF.
(32/816)
This study examined the effect of a novel circuit weight training (CWT) program on cardiorespiratory fitness, muscular strength, and body composition in 13 patients with chronic heart failure (CHF), using a prospective randomized crossover protocol. Peak exercise oxygen uptake (VO(2 peak)) increased after the 8-wk CWT program (19. 5 +/- 1.2 vs. 22.0 +/- 1.5 ml. kg(-1). min(-1), P < 0.01), as did exercise test duration (15.2 +/- 0.9 vs. 18.0 +/- 1.1 min, P < 0. 001). Submaximal exercise heart rate was lower after training at 60 and 80 W (121 +/- 3 vs. 134 +/- 5 beats/min, P < 0.01) as was rate pressure product, whereas ventilatory threshold increased, from 52 +/- 3 to 58 +/- 3% of VO(2 peak) (P < 0.05). CWT also increased maximal isotonic voluntary contractile strength for seven different muscle groups, from 392 to 462 kg (P = 0.001). CWT, an exercise prescription specifically targeting peripheral abnormalities in CHF, improves functional capacity and muscular strength in these patients. (+info)