Search results for " exercise"
showing 10 items of 1621 documents
Extreme duration exercise affects old and younger men differently.
2022
Aim & Methods: Extreme endurance exercise provides a valuable research model for understanding the adaptive metabolic response of older and younger individuals to intense physical activity. Here, we compare a wide range of metabolic and physiologic parameters in two cohorts of seven trained men, age 30 ± 5 years or age 65 ± 6 years, before and after the participants travelled ≈3000 km by bicycle over 15 days. Results: Over the 15-day exercise intervention, participants lost 2–3 kg fat mass with no significant change in body weight. V̇O2max did not change in younger cyclists, but decreased (p = 0.06) in the older cohort. The resting plasma FFA concentration decreased markedly in both gro…
Serum hormones during prolonged training of neuromuscular performance.
1985
The effects of a 24-weeks' progressive training of neuromuscular performance capacity on maximal strength and on hormone balance were investigated periodically in 21 male subjects during the course of the training and during a subsequent detraining period of 12 weeks. Great increases in maximal strength were noted during the first 20 weeks, followed by a plateau phase during the last 4 weeks of training. Testosterone/cortisol ratio increased during training. During the last 4 weeks of training changes in maximal strength correlated with the changes in testosterone/cortisol (P less than 0.01) and testosterone/SHBG (P less than 0.05) ratios. During detraining, correlative decreases were found…
Kinetics and Topology of DNA Associated with Circulating Extracellular Vesicles Released during Exercise.
2021
AbstractAlthough it is widely accepted that cancer derived extracellular vesicles (EVs) carry DNA cargo, the association of cell-free circulating DNA (cfDNA) and EVs in plasma of healthy humans remains elusive. Using a physiological exercise model, where EVs and cfDNA are synchronously released, we aimed to characterize the kinetics and localization of DNA associated with EVs. EVs were separated from human plasma using size exclusion chromatography or immuno-affinity capture for CD9+, CD63+, and CD81+ EVs. DNA was quantified with an ultra-sensitive qPCR assay targeting repetitive LINE elements, with or without DNase digestion. This model shows that a minute part of circulating cell-free DNA…
Altered oxidative stress in overtrained athletes
2010
The purpose of the present study was to examine the relationship between oxidative stress and overtraining syndrome. Indicators of oxidative stress (plasma protein carbonyls, nitrotyrosine, and malondialdehyde) and antioxidant status (oxygen radical absorbance capacity) were measured in severely overtrained (two women, five men) and control athletes (five women, five men). Samples were collected from both groups at baseline (i.e. in the overtraining state of overtrained athletes) and after 6 months of recovery, both at rest and immediately after an exercise test to volitional exhaustion. At baseline, overtrained athletes had higher plasma protein carbonyls at rest than controls (mean differ…
Innervation zone shift at different levels of isometric contraction in the biceps brachii muscle
2007
Experiments were carried out to examine whether innervation zone (IZ) location remains stable at different levels of isometric contraction in the biceps brachii muscle (BB), and to determine how the proximity of the IZ affects common surface electromyography (sEMG) parameters. Twelve subjects performed maximal (MVC) and submaximal voluntary isometric contractions at 10%, 20%, 30%, 40%, 50% and 75% of MVC. sEMG signals were recorded with a 13 rows x 5 columns grid of electrodes from the short head of BB. The IZ shifted in the proximal direction by up to 2.4 cm, depending upon the subject and electrode column. The mean shift of all the columns was 0.6+/-0.4 cm (10% vs. 100% MVC, P0.001). This…
Effects of a three-month active rehabilitation program on psychomotor performance of lower limbs in subjects with low back pain: a controlled study w…
1998
Proper psychomotor performance is needed in work and in activities of daily living, but among subjects with low back pain this area has been studied Little. The present purpose was to evaluate the effect and permanence of a 3-mo. physical exercise program on the psychomotor performance of lower limbs in subjects with low back pain. The associations between psychomotor performance and intensity of low back pain and subjective disability were also evaluated. 90 subjects with nonspecific, subacute low back pain were assigned to one of the three groups: one given three months intensive training, one home exercise, or the control group. Four measurement sessions were made during the 1-yr. study…
Is the V˙o 2 slow component dependent on progressive recruitment of fast-twitch fibers in trained runners?
2001
The goal of this study was to use spectral analysis of EMG data to test the hypothesis that the O2 uptake (V˙o 2) slow component is due to a recruitment of fast fibers. Thirteen runners carried out a treadmill test with a constant speed, corresponding to 95% of the velocity associated with maximal V˙o 2. TheV˙o 2 response was fit with the classical model including three exponential functions. Electrical activity of six lower limb muscles (vastus lateralis, soleus, and gastrocnemius of both sides) was measured using electromyogram surface electrodes. Mean power frequency (MPF) was used to study the kinetics of the electromyogram discharge frequency. Three main results were observed: 1) a co…
Reproducibility of isometric strength: measurement of neck muscles
1999
Abstract Objective. To evaluate the repeatability of an advanced method of measuring the strength of functionally different groups of neck muscles using an isometric apparatus. Design. A repeated measures design was used within and between sessions. Background. Chronic neck pain has been associated with poor isometric neck strength. In rehabilitation, strength measurements may thus help to evaluate the basic condition and show whether or not treatments and exercises have been beneficial for improving strength. Previous tests have concentrated on testing strength while trying to bend forwards and backwards, but no biomechanics device, able to test rotator muscles, has been presented. Method.…
A Comparative Study of Blood Lactate Tests in Swimming*
1989
Three different modes of lactate tests were studied. Eleven male competitive swimmers performed the tests (n.100 m, n.300 m, 2.100m + 2.400 m) within 5 days. Swimming velocity (V) vs blood lactate (BLa) and V vs heart rate (HR) curves were averaged. In V vs BLa comparisons, the BLa values of 4 mmol.l-1 in 2.400 m, 3 mmol.l-1 in n.300 m, and 2 mmol.l-1 in n.100 m modes were found to correspond to the same V. Although the resting BLa values were similar before the testing occasions, the initial BLa value in very easy swimming was lower in the n.300 m than in the n.100 m mode. The elimination of lactate most probably caused this difference. The highest BLa value was measured in the n.100 m (14…
Elderly obese women display the greatest improvement in stair climbing performance after a 3-week body mass reduction program
2004
OBJECTIVE: To depict the general trends of muscle anaerobic performance in obese subjects within a wide range of age and body weight. DESIGN: Cross-sectional study for the measurement of lower limb maximal anaerobic power output with a modification of the Margaria stair climbing test in a large population of obese subjects of both genders within a wide span of age (18-80 y) and body mass index (BMI, 30-68 kg m(-2)). Furthermore, body composition was also determined by bioimpedance analysis in a representative subgroup, in order to evaluate the relationships between fat-free mass (FFM) and power output. SUBJECTS: A total of 1298 obese subjects (486 males, 812 females) from an Italian populat…