Post-exercise Conditions Research Articles

Profiling of urinary testosterone and luteinizing hormone in exercise-stressed male athletes, using gas chromatography-mass spectrometry and enzyme immunoassay techniques.

Knowledge of the effects of episodic or short-term exercise-stress on endogenous testosterone and luteinizing hormone levels still remains fragmentary and inconclusive. In this study, an approach based on the absolute concentrations of urinary total testosterone (T), luteinizing hormone (LH) and the T/LH concentration ratios, was used to profile short-term exercise-stress responses in healthy drug-free male athletes. Testosterone and luteinizing hormone concentrations were measured using gas chromatography-mass spectrometry (GC-MS) and microparticle enzyme immunoassay (MEIA) techniques, respectively. Stress profiles derived from exercise-stress at VO2max, 68.1% VO2max and 51.6% VO2max were plotted using the concentrations of T, LH and the ratios of T/LH found under non-stressed and stressed conditions. Significant changes in LH concentrations (p < 0.005) and T/LH ratios (p < 0.005) levels were observed between the pre-stress and post-exercise conditions during acute exercise-stress at VO2max but the T concentration did not show any marked change relative to the non-stressed condition. Whilst exercise-stress appeared to reduce the change in T concentrations between the pre- and post-exercise states compared to that in the non-stressed control condition, the change in LH concentrations showed a moderate increase at submaximal oxygen uptake values. The stress profiles derived from this study facilitated an assessment of the relationship between the endogenous T, LH and T/LH ratio stress-responses over a short period of applied exercise-stress.

EEG correlates of exercise dependency

Jacobs' (1986) proposition that dependency is the result of two sets of predisposing factors (one of which is either an excessively depressed or excited resting physiological state) was examined in relation to exercise dependency by investigating EEG characteristics of subjects committed to fitness regimes. EEG records of three groups of subjects who differed in terms of degree of dependency were studied under resting conditions both pre- and post-exercise. The results indicated that although there were no differences between groups in terms of relative power in each of five EEG bandwidths covering the range 0 to 30 Hz, the power distribution within the alpha (7.5–13 Hz) bandwidth was significantly different for high dependent and non-dependent groups under both the pre- and post-exercise conditions. While the distribution was skewed toward the lower alpha frequencies for the low dependent group, it was skewed toward the higher frequencies for the high dependent group with the distribution for a group with high involvement but low dependency falling between these extremes. This finding is taken as partial support for Jacobs' notion that dependency is associated with greater physiological excitation in the resting state.

Acute exercise enhances nitric oxide modulation of vascular response to phenylephrine

The influence of the release of endothelium-derived nitric oxide (NO) on the vasoconstrictor response to phenylephrine (PE) was evaluated before and after a single bout of dynamic exercise. Each rat ran on a motor-driven treadmill at 12-18 m/min, 10-18% grade until exhaustion (avg time 45 min). Sprague-Dawley rats (n = 6) were instrumented with a Doppler ultrasonic flow probe around the right common iliac artery. Just distal to the flow probe, a catheter was placed into the right iliac artery for local infusions. A Teflon catheter was placed in the descending aorta to measure mean arterial blood pressure (MAP) and heart rate (HR). PE (0.005-0.075 microgram/kg) and NO inhibitor N omega-nitro-L-arginine methyl ester hydrochloride (L-NAME, 0.2-0.25 mg/kg) were injected into the functionally isolated hindlimb. HR and MAP were not altered by any of the injections because we selected doses below those which elicited systemic responses. Dose-response curves to PE were generated in the control and postexercise condition, with and without the NO synthase inhibitor L-NAME. Exercise significantly attenuated the maximal vasoconstrictor response to PE (45.6 +/- 1.6%). L-NAME enhanced the maximal vasoconstrictor response to PE 49.8 +/- 4.5% in the control condition and 121.4 +/- 5.9% in the postexercise conditions. Thus, although NO inhibition enhanced the vasoconstrictor response to PE in the control and postexercise conditions, the enhanced vasoconstrictor response to PE after L-NAME was significantly greater in the postexercise condition. Results suggest that NO contributes to the exercise induced attenuation of alpha 1-adrenergic receptor stimulation.

The regulatory, informational, and immunomodulatory roles of fat fuels

Fat oxidation provides a fuel for many tissues and it provides an important signal to decrease glucose utilization and oxidation in muscle and so conserve glucose for essential organs such as the brain. The control of fatty acid oxidation is achieved in part through its plasma concentrations, which may be precisely controlled by the triacylglycerol-fatty acid substrate cycle, which can also, if oxidation is taken into account, be viewed as a branch point in this important pathway. Branch points may provide precision in regulation if one of the fluxes at the branch is low compared with the other flux. Both branch points and substrate cycles are energetically expensive and may account for some of the increases in energy expenditure in conditions of injury, burns, and sepsis and in the postexercise condition. Fatty acids, through effects on plasma free tryptophan concentrations and hence 5-hydroxytryptamine concentrations in the brain, may play a role in central fatigue. Polyunsaturated fatty acids are claimed to have immunosuppressive properties. Work has been done to provide a biochemical analysis of how they might influence some functions of cells of the immune system.

Numerical Analysis of Physiological Flow in a Curved Tube. Model of an Aortic Arch Flow.

Human aortic arch flow was regarded as an intermittent flow in a curved tube with large curvature ratio δ=1/3. The waveform of aortic flow was obtained by means of Doppler echocardiography from both resting and post-exercise conditions of healthy human adults (age : 22∼27). The result in the resting condition (Re=2300, α=13.34) shows that the transverse flow field is characterized by the appearance of three vertices (residue vortex from the previous cycle, one generated near the Stokes layer, and one induced by development of axial velocity boundary layer in the systole). In the post-exercise condition (Re=3400, α=16.7), a Lyne vortex appears in the end of systolic period and exists until the beginning of systolic phase, together with the vertices generated in the diastolic phase. Furthermore multiple period solutions were found numerically for several flow conditions. Our calculation indicates the aortic flow may have multiple period solutions, but its physiological significance is not yet clear.

Postprandial thermogenesis at rest and postexercise before and after physical training in lean, obese, and midly diabetic men

To determine the independent impact of physical training on postprandial thermogenesis at rest and after 1 hour of cycling at 100 W, 10 lean (15% ± 1% body fat), 10 obese (33% ± 2% fat), and six obese diet-controlled, type II diabetic men (34% ± 4% fat) underwent 12 weeks of vigorous cycle ergometer training (4 h/wk at ∼70% of maximum oxygen consumption [VO 2max]) while maintaining body weight and composition. Body weight was held constant by refeeding the energy expended in each training session. Cardiorespiratory fitness increased by approximately 27%, but body weight and fat did not change. Before and at least 4 days after the last exercise session, energy expenditure was measured for 3 hours under four conditions: (1) rest, no meal; (2) rest, after a 720-kcal mixed meal; (3) postexercise after 1 hour cycling, no meal; and (4) postexercise, meal after exercise. The thermic effect of food was calculated as postprandial minus postabsorptive energy expenditure at rest and postexercise (kcal/3 h). Before and after training, the thermic effect of food during rest was lower in obese than in lean men, and lower in diabetic than in obese men ( P < .05). Thermogenesis was improved after short-term exercise in obese and diabetic men compared with that at rest, but was not normalized ( P < .05 for lean v obese, diabetic men). A significant effect of training on thermogenesis was due to a small but significant increase after training for diabetic men under the postexercise condition. Thus, while short-term exercise enhances but does not normalize thermogenesis in obese and diabetic men, long-term exercise training leading to increased cardiorespiratory fitness, in the absence of changes in body composition, leads to a small increase in thermogenesis in diabetic men, which manifests only after a short period of exercise.

Influence of post-exercise activity on plasma catecholamines, blood pressure and heart rate in normal subjects.

The purpose of this study was to evaluate whether or not the type of activity performed during recovery might influence the magnitude of catecholamine outflow following exercise. Six active, male volunteers between 40-52 years recovered from strenuous treadmill exercise in three different ways; standing, supine rest and walking (2 mph, 0% grade). Measurements of noradrenaline (NA), adrenaline (A), heart rate and blood pressure were made at rest, peak exercise, and at 30 s intervals through 5-min of recovery. Peak exercise NA concentrations were approximately 1000% above those recorded as rest. Early recovery was marked by a continued increase in NA from peak exercise concentrations (4614 +/- 548 vs. 3264 +/- 485 pg/ml) which did not return to peak exercise levels until approximately 90 s of recovery. Adrenaline responses followed similar trends; however, the changes were not as sizable. Heart rate and diastolic blood pressure were significantly affected by the post-exercise condition; supine recovery produced significantly lower mean heart rates and mean diastolic blood pressures in comparison to standing or continued walking recovery conditions. Thus, these data indicate no specific recovery strategy will stem the rise in exercise-induced plasma catecholamines. Clinically, a strategy of continued walking, or better, supine recovery will best meet special clinical requirements, as well as limit the magnitude of the peak catecholamine increases.

Lower thermic effect of a meal post-exercise in aerobically trained and resistance-trained subjects

Despite the abundance of literature concerning the thermic effect of a test meal (TEM) at rest in trained and untrained subjects, there is little information available concerning the TEM post-exercise. Therefore, it was the purpose of this study to examine the metabolic response to a 763-kcal meal prior to 30 min of exercise at 50% V̇O2max, in aerobically trained (AT, N = 8), resistance-trained (RT, N= 8), and untrained (UT, N=8) subjects. Mean (±SEM) V̇O2max was 60.7 ± 2.3 ml·kg−1·min−1, 52.9 ± 2.2 ml·kg−1·min−1, and 51.1 ± 2.2 ml·kg−1·min−1, for the AT, RT, and UT groups, respectively. Mean (±SEM) percent fat was 13.7 ± 1.2, 12.7 ± 1.9, and 16.9 ± 1.4 for the AT, RT, and UT groups, respectively. Post-exercise V̇O2 was measured by indirect calorimetry every half hour, on two nonconsecutive days (post-absorptive (PA) post-exercise and post-prandial (PP) post-exercise) for 3 h. The total TEM (post-exercise PP V̇O2 minus post-exercise PA V̇O2) was 4.86 ± 1.62, 5.22 ± 1.80, and 9.36 ± 5.081 for the AT, RT, and UT groups, respectively. The TEM post-exercise was significantly lower (P < 0.05) for the AT and RT groups compared with the UT group. Respiratory exchange ratio (R) differed significantly only during the PA post-exercise condition, with the AT group exhibiting significantly lower (P < 0.01) values compared with the RT and UT groups. PA post-exercise R for the RT group was not significantly different (P = 0.09) from the UT group. These data suggest that the consumption of a meal 30 min prior to exercise results in a lower TEM post-exercise in AT and RT subjects. However, the AT group may utilize a higher percentage of fat as substrate following post-absorptive exercise.

304 LOWER THERMIC EFFECT OF FOOD POST-EXERCISE IN AEROBICALLY-TRAINED AND RESISTANCE-TRAINED SUBJECTS

Despite the abundance of literature concerning the thermic effect of a test meal (TEM) at rest in trained and untrained subjects, there is little information available concerning the TEM post-exercise. Therefore, it was the purpose of this study to examine the metabolic response to a 763-kcal meal prior to 30 min of exercise at 50% VO2max, in aerobically trained (AT, N = 8), resistance-trained (RT, N = 8), and untrained (UT, N = 8) subjects. Mean (+/- SEM) VO2max was 60.7 +/- 2.3 ml.kg-1.min-1, 52.9 +/- 2.2 ml.kg-1.min-1 and 51.1 +/- 2.2 ml.kg-1.min-1, for the AT, RT, and UT groups, respectively. Mean (+/- SEM) percent fat was 13.7 +/- 1.2, 12.7 +/- 1.9, and 16.9 +/- 1.4 for the AT, RT, and UT groups, respectively. Post-exercise VO2 was measured by indirect calorimetry every half hour, on two nonconsecutive days (post-absorptive (PA) post-exercise and post-prandial (PP) post-exercise) for 3 h. The total TEM (post-exercise PP VO2 minus post-exercise PA VO2) was 4.86 +/- 1.62, 5.22 +/- 1.80, and 9.36 +/- 5.08 I for the AT, RT, and UT groups, respectively. The TEM post-exercise was significantly lower (P less than 0.05) for the AT and RT groups compared with the UT group. Respiratory exchange ratio (R) differed significantly only during the PA post-exercise condition, with the AT group exhibiting significantly lower (P less than 0.01) values compared with the RT and UT groups. PA post-exercise R for the RT group was not significantly different (P = 0.09) from the UT group.(ABSTRACT TRUNCATED AT 250 WORDS)

An in Vitro Model of Post-Exercise Hepatic Gluconeogenesis in the Gulf Toadfish Opsanus Beta

ABSTRACT During strenuous exercise, fish develop substantial proton and lactate loads. Although acidosis is usually rapidly corrected during recovery (1–2 h), lactate levels often remain elevated for up to 8–12 h. The quantitative role of the liver in clearance of the lactate load during recovery from exercise in fish has received little direct examination. The purposes of this study were (1) to attempt to quantify hepatic contribution to lactate clearance, and (2) to identify factors that regulate hepatic gluconeogenesis during recovery from exercise in fish. Both in vivo and in vitro (isolated hepatocytes) approaches were used. Important blood parameters (pHe, , [lactate], [glucose], [epinephrine] and [norepinephrine]) were measured in the gulf toadfish (Opsanus beta Goode and Bean) during recovery from strenuous exercise, and they conformed to the general patterns for sluggish benthic species noted in earlier studies. When toadfish hepatocytes were exposed to simulated post-exercise conditions in vitro, gluconeogenesis from lactate was stimulated by over 2·5-fold in ‘0–1 h-’ and ‘l–2h-post-exercise periods’. Variation of the extracellular parameters in controlled combinations indicated that exercise-induced changes in [glucose], [epinephrine], [norepinephrine], and [HCO3−] had no significant effects on rates of gluconeogenesis. The observed stimulation of gluconeogenesis could be induced independently by either decreased pH (which lowered Km for lactate) or increased [lactate] (by simple hyperbolic kinetic effects), but the effects were not additive. Despite this potentially adaptive stimulation of gluconeogenesis, I estimate, based on observed in vitro rates and in vivo estimates of lactate load, that hepatic gluconeogenesis accounts for less than 2 % of the lactate load clearance in toadfish.

Exercise moderation of foot function during walking with a re-usable semirigid ankle orthosis

A study was conducted to investigate the effects of a re-usable semirigid ankle orthosis on the support phase of the walking stride in both pre- and post-exercise conditions. Ten young, adult males were required to complete ten trials in each of four orthosis/no orthosis and pre-/post-exercise conditions. Data were collected via a force platform and a high speed camera. The analysis consisted of the evaluation of selected ground reaction force parameters and kinematic parameters describing rearfoot motion. The exercise regimen consisted of 70 maximal eccentric actions of the ankle everters, with 15 s between each action. The results revealed significant differences between the orthosis/no orthosis conditions for the variables describing the mediolateral action of the ankle during walking. Only the rearfoot touchdown angle was affected by the exercise regimen. The data indicated that the semirigid orthosis moderated ankle joint mechanics, although the measured values were within normal bounds.

Effect of Exercise upon the Measurable Supporting Strength of Cloth and Tape Ankle Wraps

Abstract Observations were made on the supporting strength of three types of ankle wraps before and after exercise. The ankle wraps under investigation included the tape-on-skin, tape-over-stockinette, and the Louisiana wrap. A cable tensiometer and a mounted range of motion indicator were used to obtain simultaneous force and range of motion data as the foot was manually moved in plantar flexion-inversion. Ten college men were tested with each type of ankle wrap and with the ankle unwrapped under both pre-exercise and post-exercise conditions. The results showed that although the measurable support varied with type of wrapping and with individuals, the supporting strength of all wraps declined substantially following exercise. The tape-on-skin wrap proved to be superior in supporting strength both before and after exercise.