Search results for "oxygen consumption"
showing 10 items of 347 documents
Biceps brachii muscle oxygenation in electrical muscle stimulation
2010
The purpose of this study was to compare between electrical muscle stimulation (EMS) and maximal voluntary (VOL) isometric contractions of the elbow flexors for changes in biceps brachii muscle oxygenation (tissue oxygenation index, TOI) and haemodynamics (total haemoglobin volume, tHb = oxygenated-Hb + deoxygenated-Hb) determined by near-infrared spectroscopy (NIRS). The biceps brachii muscle of 10 healthy men (23-39 years) was electrically stimulated at high frequency (75 Hz) via surface electrodes to evoke 50 intermittent (4-s contraction, 15-s relaxation) isometric contractions at maximum tolerated current level (EMS session). The contralateral arm performed 50 intermittent (4-s contrac…
Achilles tendon stiffness is unchanged one hour after a marathon
2012
Overuse-induced injuries have been proposed as a predisposing factor for Achilles tendon (AT) ruptures. If tendons can be overloaded, their mechanical properties should change during exercise. Because there data are lacking on the effects of a single bout of long-lasting exercise on AT mechanical properties, the present study measured AT stiffness before and after a marathon. AT stiffness was determined as the slope of the force–elongation curve between 10 and 80% of maximum voluntary force. AT force–elongation characteristics were measured in an ankle dynamometer using simultaneous motion-capture-assisted ultrasonography. Oxygen consumption and ankle kinematics were also measured on a trea…
Influence of exercise training on physiological and performance changes with weight loss in men.
1999
The purpose of this study was to examine the physiological effects of a weight-loss dietary regimen with or without exercise.Thirty-five overweight men were matched and randomly placed into either a control group (C; N = 6) or one of three dietary groups; a diet-only group (D; N = 8), a diet group that performed aerobic exercise three times per week (DE; N = 11); and a diet group that performed both aerobic and strength training three times per week (DES; N = 10).After 12 wk, D, DE, and DES demonstrated a similar and significant (Por = 0.05) reduction in body mass (-9.64, -8.99, and -9.90 kg, respectively) with fat mass comprising 69, 78, and 97% of the total loss in body mass, respectively…
Plasma catecholamine responses and neural adaptation during short-term resistance training
2000
Low exercise-induced plasma adrenaline (A) responses have been reported in resistance-trained indi- viduals. In the study reported here, we investigated the interaction between strength gain and neural adaptation of the muscles, and the plasma A response in eight healthy men during a short-term resistance-training period. The subjects performed 5 resistance exercises (E1-E5), consisting of 6 sets of 12 bilateral leg exten- sions performed at a 50% load, and with 2 days rest in between. Average electromyographic (EMG) signal amplitude was recorded before and after the exercises, from the knee extensor muscles in isometric maximal voluntary contraction (MVC) as well as during the exercises (a…
Effects of oxygen fraction in inspired air on force production and electromyogram activity during ergometer rowing
1997
Six male rowers rowed maximally for 2500 m in ergometer tests during normoxia (fractional concentration of oxygen in inspired air, F IO2 0.209), in hyperoxia (F IO2 0.622) and in hypoxia (F IO2 0.158) in a randomized single-blind fashion. Oxygen consumption (V˙O2), force production of strokes as well as integrated electromyographs (iEMG) and mean power frequency (MPF) from seven muscles were measured in 500-m intervals. The iEMG signals from individual muscles were summed to represent overall electrical activity of these muscles (sum-iEMG). Maximal force of a stroke (F max) decreased from the 100% pre-exercise maximal value to 67 (SD 12)%, 63 (SD 15)% and 76 (SD 13)% (P<0.05 to normoxia, AN…
Combined strength and endurance session order: differences in force production and oxygen uptake.
2015
Purpose:To examine acute responses of force production and oxygen uptake to combined strength (S) and endurance-running (E) loading sessions in which the order of exercises is reversed (ES vs SE).Methods:This crossover study design included recreationally endurance-trained men and women (age 21−45 y; n = 12 men, 10 women) who performed ES and SE loadings. Force production of the lower extremities including countermovement-jump height (CMJ) and maximal isometric strength (MVC) was measured pre-, mid-, and post-ES and -SE, and ground-reaction forces, ground-reaction times, and running economy were measured during E.Results:A significant decrease in CMJ was observed after combined ES and SE in…
Differences in ground reaction forces and shock impacts between nordic walking and walking.
2014
The regular practice of Nordic walking (NW) has increased in recent years, in part thanks to the health benefits described by the scientific literature. However, there is no consensus on the effects of shock-impact absorption during its practice. Purpose: The aim of this study was to compare the levels of impact and ground reaction forces (GRF) between NW and walking (W). Method: Twenty physically active and experienced participants were assessed using a dynamometric platform and accelerometry analysis. Results: The results show statistically significantly higher levels of acceleration in the tibia (12%) and head (21%) during NW compared with W. Equally, GRF were significantly higher (27%) …
Serum hormone and myocellular protein recovery after intermittent runs at the velocity associated with VO(2max).
1999
The responses of serum myocellular proteins and hormones to exercise were studied in ten well-trained middle-distance runners [maximal oxygen consumption (VO(2max)) = 69.4 (5.1) ml x kg(-1) x min(-1)] during 3 recovery days and compared to various measures of physical performance. The purpose was to establish the duration of recovery from typical intermittent middle-distance running exercises. The subjects performed, in random, order two 28-min treadmill running exercises at a velocity associated with VO(2max): 14 bouts of 60-s runs with 60 s of rest between each run (IR(60)) and 7 bouts of 120-s runs with 120 s of rest between each run (IR(120)). Before the exercises (pre- exercise), 2 h a…
Effects of a Heart Rate–Based Recovery Period on Hormonal, Neuromuscular, and Aerobic Performance Responses During 7 Weeks of Strength Training in Men
2011
The purpose of this study was to compare hormonal, neuromuscular, and aerobic performance changes between a constant 2-minute interset recovery time and an interset recovery time based on individual heart rate (HR) responses during a 7-week (3 sessions per week, 3 × 10 repetition maximum [RM]) hypertrophic strength training period. The HR-dependent recovery time was determined with a Polar FT80 HR monitor, whereas the control groups used constant 2-minute periods between sets. From 24 male subjects who were divided in 2 equal groups, 21 completed the study (FT80, n = 12; CONTROL, n = 9). Serum blood samples analyzed for testosterone (TES) and cortisol (COR) were taken before and after the 7…
Strength training in endurance runners.
2010
This study examined effects of periodized maximal versus explosive strength training and reduced strength training, combined with endurance training, on neuromuscular and endurance performance in recreational endurance runners. Subjects first completed 6 weeks of preparatory strength training. Then, groups of maximal strength (MAX, n=11), explosive strength (EXP, n=10) and circuit training (C, n=7) completed an 8-week strength training intervention, followed by 14 weeks of reduced strength training. Maximal strength (1RM) and muscle activation (EMG) of leg extensors, countermovement jump (CMJ), maximal oxygen uptake (VO(2MAX)), velocity at VO(2MAX) (vVO(2MAX)) running economy (RE) and basal…