Search results for "Exertion"
showing 10 items of 258 documents
Reduced stretch reflex sensitivity and muscle stiffness after long-lasting stretch-shortening cycle exercise in humans
1998
It has been suggested that during repeated long-term stretch-shortening cycle (SSC) exercise the decreased neuromuscular function may result partly from alterations in stiffness regulation. Therefore, interaction between the short latency stretch-reflex component (M1) and muscle stiffness and their influences on muscle performance were investigated before and after long lasting SSC exercise. The test protocol included various jumps on a sledge ergometer. The interpretation of the sensitivity of the reflex was based on the measurements of the patellar reflexes and the M1 reflex components. The peak muscle stiffness was measured indirectly and calculated as a coefficient of the changes in the…
Physiological responses and parasympathetic reactivation in rescue interventions: The effect of the breathing apparatus.
2018
This study aimed to assess the effect of wearing a breathing apparatus during a simulated rescue intervention on psychophysiological responses and parasympathetic reactivation of firefighters. Thirty-four firefighters participated in this study which consisted of four experimental sessions conducted randomly: a maximal fitness test and three rescue interventions performed (a) with personal protective clothing (PPC); (b) with PPC and the full self-contained breathing apparatus (SCBA), including cylinder, full-face piece, and breathing regulator; and (c) with PPC and only the cylinder of the self-contained breathing apparatus (SCBAc). Physiological (heart rate [HR], breathing frequency [BF]) …
Changes in Salivary Levels of Creatine Kinase, Lactate Dehydrogenase, and Aspartate Aminotransferase after Playing Rugby Sevens: The Influence of Gen…
2020
Rugby sevens is characterised by continuous exertion and great physical contact per unit of time, leading to muscle damage. It is important to identify markers that can quantify muscle damage in order to improve recovery strategies. The objective of this study was to evaluate the release dynamics of muscle damage markers creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) in saliva samples when playing rugby sevens, analysing the influence of gender, during the rugby sevens university championship of Spain. The total sample included 27 athletes, divided into two teams of 14 men and 13 women between 18 and 31 years of age. CK, LDH, and AST were quantified …
Cardiorespiratory and Neuromuscular Responses to Motocross Riding
2008
The aim of the present study was to examine physiological and neuromuscular responses during motocross riding at individual maximal speed together with the riding-induced changes in maximal isometric force production. Seven A-level (group A) and 5 hobby-class (group H) motocross-riders performed a 30-minute riding test on a motocross track and maximal muscle strength and oxygen uptake (VO2max) tests in a laboratory. During the riding the mean (+/-SD) VO2 reduced in group A from 86 +/- 10% to 69 +/- 6% of the maximum (P < 0.001), whereas in group H the corresponding reduction was from 94 +/- 25% to 82 +/- 20% (P < 0.05). This relative VO2 during the riding correlated with riding speed (r = 0…
Acute Physiological Responses to Four Running Sessions Performed at Different Intensity Zones
2020
AbstractThis study investigated acute responses and post 24-h recovery to four running sessions performed at different intensity zones by supine heart rate variability, countermovement jump, and a submaximal running test. A total of 24 recreationally endurance-trained male subjects performed 90 min low-intensity (LIT), 30 min moderate-intensity (MOD), 6×3 min high-intensity interval (HIIT) and 10×30 s supramaximal-intensity interval (SMIT) exercises on a treadmill. Heart rate variability decreased acutely after all sessions, and the decrease was greater after MOD compared to LIT and SMIT (p<0.001; p<0.01) and HIIT compared to LIT (p<0.01). Countermovement jump decreased only after …
Interaction of atenolol with furosemide and calcium and aluminum salts
1981
Six healthy subjects were treated with 100 mg atenolol. After a therapy-free interval of 4 wk the same subjects received the same dose of atenolol with furosemide, 40 mg, with calcium (as the lactate gluconate and carbonate), 500 mg, or with aluminum hydroxide, 5.6 gm. Atenolol alone and in combination was administered first as a single oral dose; a long-term 6-day treatment began 48 hr later. Addition of furosemide did not influence atenolol kinetics, but aluminum hydroxide led to an insignificant reduction (P greater than 0.05) of mean peak plasma levels of about 20% and of the area under the plasma concentration-time curve (AUC -infinity) from 5818 to 4353 ng ml-1 hr (P greater than 0.05…
The effect of an 1100 km run on testicular, adrenal and thyroid hormones
1984
Although endocrine effects of physical or psychological stress are well documented, it is not known to what extent adaptation to prolonged exertion occurs. We therefore investigated the impact of an 1100 km run of 20 days' duration on selected pituitary, testicular, adrenal and thyroid hormones. Blood samples were obtained from five male athletes prior to and after the day's run on the 1st, 5th, 9th, 14th and 19th day. Results show that adrenal and thyroid function soon adapt to the daily strain. Testosterone levels, however, were markedly decreased throughout the 20 days while LH levels remained unchanged. Thus it appears that the reproductive endocrine system is more susceptible to long-t…
Cycling exercise and the determination of electromechanical delay.
2007
The main aim of the present paper was to address the validity of a methodology proposed in a previous paper [Li L, Baum BS. Electromechanical delay estimated by using electromyography during cycling at different pedaling frequencies. J Electromyogr Kinesiol 2004;14(6):647-52], aimed at determining the electromechanical delay from pedaling exercise performed at various cadences. Twelve trained subjects undertook pedaling bouts corresponding to combinations of cadences ranging from 50 to 100 RPM and power output from 37.5% to 75% of Pmax. As cadence increased, peak torque angle was found to shift forward in crank cycle (from 60-65 degrees at 50 RPM to 75-80 degrees at 100 RPM, depending on th…
Fatigue-related changes in technique emerge at different timescales during repetitive training
2017
Training consisting of numerous repetitions performed as closely as possible to ideal techniques is common in sports and every-day tasks. Little is known about fatigue-related technique changes that emerge at different timescales when repeating complex actions such as a karate front kick. Accordingly, 15 karatekas performed 600 kicks (1 pre-block and 9 blocks). The pre-block comprised 6 kicks (3 with each leg) at maximum intensity (K-100%). Each block comprised 60 kicks (10 with each leg) at 80% of their self-perceived maximum intensity (K-80%) plus 6 K-100%. In between blocks, the participants rested for 90 seconds. Right leg kinematics (peak joint angles, peak joint angular velocities, pe…
Effect of cycling specialization on effort and physiological responses to uphill and flat cycling at similar intensity
2020
Power output is considered one of the best tools to control external loads in cycling, but the relationship between a target power output and the physiological responses may suffer from the effects of road gradient, which is also affected by cyclist specialization. The objective was to determine the effects of cyclist specialization on effort perception and physiological response (heart rate and lactate concentration) while sustaining efforts at similar power output but riding on two different road gradients. Nineteen male competitive road cyclists performed two randomized trials of 10 min at 0% (velodrome) and 10 min at 6% road gradient (field uphill), at an intensity of 10% ± 3% below the…