Search results for "Exertion"
showing 10 items of 258 documents
Voluntary activation and mechanical performance of human triceps surae muscle after exhaustive stretch-shortening cycle jumping exercise.
2003
The purpose of this study was to examine neuromuscular factors that may contribute to post exercise force loss and subsequent recovery after exhaustive stretch-shortening cycle (SSC) exercise. Six subjects were fatigued on a sledge apparatus by 100 maximal rebound jumps followed by continuous submaximal jumping until complete exhaustion. Exercise-induced changes in neuromuscular performance were followed up to 7 days post exercise. The total number of jumps in the SSC exercise ranged from 336 to 1392. The SSC exercise induced a significant immediate plantarflexion torque decline of 29, 38 and 44% (P<0.05) in maximal voluntary contraction and evoked maximal twitch and low-frequency (LF) stim…
The effect of fatigue on store and re-use of elastic energy in slow and fast types of human skeletal muscle
1986
Stretch-shortening exercises are characterized by enhancement of performance when compared to the work output performed in shortening conditions. There is evidence that fast subjects are unable to re-use great amounts of elastic energy during stretch-shortening cycles performed with slow stretching speed and large stretching length. In the present study, 14 subjects possessing different fibre types in m. vastus lateralis performed vertical jumps with and without preliminary countermovement and with large angular displacement and slow stretching speed The jumping tests were executed before and immediately after fatigue induced by short intense exercises (60 s of continuous rebound jumping). …
Mechanism of Free Radical Production in Exhaustive Exercise in Humans and Rats; Role of Xanthine Oxidase and Protection by Allopurinol
2000
Exhaustive exercise generates free radicals, However, the source of this oxidative damage remains controversial. The aim of this paper was to study further the mechanism of exercise-induced production of free radicals, Testing the hypothesis that xanthine oxidase contributes to the production of free radicals during exercise, me found not only that exercise caused an increase in blood xanthine oxidase activity in rats but also that inhibiting xanthine oxidase with allopurinol prevented exercise-induced oxidation of glutathione in both rats and in humans. Furthermore, inhibiting xanthine oxidase prevented the increases in the plasma activity of cytosolic enzymes (lactate dehydrogenase, aspar…
Oxidative stress in marathon runners: interest of antioxidant supplementation
2006
We have recently reported that xanthine oxidase is involved in the generation of free radicals in exhaustive exercise. Allopurinol, an inhibitor of xanthine oxidase, prevents it. The aim of the present work was to elucidate the role of exercise-derived reactive oxygen species in the cell signalling pathways involved in the adaptation to exercise in man. We have found that exercise causes an increase in the activity of plasma xanthine oxidase and an activation of NF-κB in peripheral blood lymphocytes after marathon running. This activation is dependent on free radical formation in exercise: treatment with allopurinol completely prevents it. In animal models, we previously showed that NF-κB a…
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…
Effect of 3 Weeks Use of Compression Garments on Stride and Impact Shock during a Fatiguing Run
2015
Excessive and prolonged exposure to impact acceleration during running is associated with increased injury rate. Acute use of compressive garments has been speculated to improve attenuation. However, it is unknown how longer interventions of compressive garments influence attenuation in running. 40 runners trained with compressive and placebo stockings for 3 weeks. Perception of comfort, stride parameters (rate, length) and impact acceleration (head and tibial peak acceleration, magnitude, acceleration rate and attenuation) were measured every 5 min during a fatigue run (30 min at 80% of the individual's maximal aerobic speed). Compressive stockings reduced tibial peak acceleration and magn…
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…
Endocrine Response Patterns to Acute Unilateral and Bilateral Resistance Exercise in Men
2009
Rehabilitation programs and research experiments use single-arm protocols in which the contralateral arm is not functional or used as a control limb. This study was interested in determining the hormonal signal impacts of such one- versus two-arm exercise responses that might have an impact on adaptational changes with training. The purpose was to examine the acute hormonal responses to a unilateral and a bilateral upper-body resistance exercise (RE) protocol. A balanced randomized treatment intervention with series time frame for blood collections before and after exercise was used as the basic experimental design. Ten recreationally resistance trained men (18-25 years, 20.4 +/- 1.2 years,…
Concurrent validation of the OMNI-resistance exercise scale of perceived exertion with Thera-band resistance bands.
2012
The concurrent validity of the OMNI-Resistance Exercise Scale (OMNI-RES) of perceived exertion for use with elastic bands was studied during isotonic resistance exercises. Twenty healthy, physically active subjects completed both familiarization and testing sessions. The criterion variables were myoelectric activity, recorded by electromyography, and heart rate, recorded by a heart rate monitor. The subjects performed 2 separate sets of 15 repetitions in each of the 2 testing sessions and for each of the exercises applied (i.e., frontal and lateral raises). One set was carried out with the separation between the hands gripping the elastic band allowing that 15 repetition maximum to be perfo…
Endogenous opioid peptide responses to opioid and anti-inflammatory medications following eccentric exercise-induced muscle damage.
2009
To determine the effects of Vicoprofen, Ibuprofen, and a placebo on the responses of endogenous opioid peptides following eccentric exercise-induced muscle damage 36 healthy men (age: 22.8 years; height: 178.8+/-6.2cm; body mass: 78.9+/-13.7kg; body fat: 15.8+/-6.5%) volunteered to participate in the study. Each participant was evaluated for pain 24h post and randomly assigned to an experimental group: VIC (Vicoprofen), IBU (Ibuprofen), or P (placebo). Medication was given four times daily (i.e., VIC (hydrocodone bitartrate 7.5mg with Ibuprofen 200mg) and IBU 200mg). Blood was obtained at rest and at 0, 24, 48, 72, 96 and 120h following the eccentric exercise damage protocol. No significant…