The athlete's heart: allometric considerations on published papers and relation to cardiovascular variables.

To evaluate the morphology of the "athlete's heart", left ventricular (LV) wall thickness (WT) and end-diastolic internal diameter (LVIDd) at rest were addressed in publications on skiers, rowers, swimmers, cyclists, runners, weightlifters (n = 927), and untrained controls (n = 173) and related to the acute and maximal cardiovascular response to their respective disciplines. Dimensions of the heart at rest and functional variables established during the various sport disciplines were scaled to body weight for comparison among athletes independent of body mass. The two measures of LV were related (r = 0.

Dose of Bicarbonate to Maintain Plasma pH During Maximal Ergometer Rowing and Consequence for Plasma Volume.

Rowing performance may be enhanced by attenuated metabolic acidosis following bicarbonate (BIC) supplementation. This study evaluated the dose of BIC needed to eliminate the decrease in plasma pH during maximal ergometer rowing and assessed the consequence for change in plasma volume. Six oarsmen performed "2,000-m" maximal ergometer rowing trials with BIC (1 M; 100-325 ml) and control (CON; the same volume of isotonic saline).

The Effect of Hyperoxia on Central and Peripheral Factors of Arm Flexor Muscles Fatigue Following Maximal Ergometer Rowing in Men.

Purpose: This study evaluates the effect of hyperoxia on cerebral oxygenation and neuromuscular fatigue mechanisms of the elbow flexor muscles following ergometer rowing.

Methods: In 11 competitive male rowers (age, 30 ± 4 years), we measured near-infrared spectroscopy determined frontal lobe oxygenation (ScO) and transcranial Doppler ultrasound determined middle cerebral artery mean flow velocity (MCA ) combined with maximal voluntary force (MVC), peak resting twitch force ( ) and cortical voluntary activation (VA) of the elbow flexor muscles using electrical motor point and magnetic motor cortex stimulation, respectively, before, during, and immediately after 2,000 m all-out effort on rowing ergometer with normoxia and hyperoxia (30% O).

Results: Arterial hemoglobin O saturation was reduced to 92.

Fluctuations in cardiac stroke volume during rowing.

Preload to the heart may be limited during rowing because both blood pressure and central venous pressure increase when force is applied to the oar. Considering that only the recovery phase of the rowing stroke allows for unhindered venous return, rowing may induce large fluctuations in stroke volume (SV). Thus, the purpose of this study was to evaluate SV continuously during the rowing stroke.

The physiology of rowing with perspective on training and health.

Purpose: This review presents a perspective on the expansive literature on rowing.

Methods: The PubMed database was searched for the most relevant literature, while some information was obtained from books.

Results: Following the life span of former rowers paved the way to advocate exercise for health promotion.

CO supplementation dissociates cerebral oxygenation and middle cerebral artery blood velocity during maximal cycling.

This study evaluated whether the reduction of prefrontal cortex oxygenation (ScO ) during maximal exercise depends on the hyperventilation-induced hypocapnic attenuation of middle cerebral artery blood velocity (MCA V ). Twelve endurance-trained males (age: 25 ± 3 years, height: 183 ± 8 cm, weight: 75 ± 9 kg; mean ± SD) performed in three separate laboratory visits, a maximal oxygen uptake (VO max) test, an isocapnic (end-tidal CO tension (PetCO ) clamped at 40 ± 1 mmHg), and an ambient air controlled-pace constant load high-intensity ergometer cycling to exhaustion, while MCA V (transcranial Doppler ultrasound) and ScO (near-infrared spectroscopy) were determined. Duration of exercise (12 min 25 s ± 1 min 18 s) was matched by performing the isocapnic trial first.

Cardiac output during exercise is related to plasma atrial natriuretic peptide but not to central venous pressure in humans.

New Findings: What is the central question of this study? Is cardiac output during exercise dependent on central venous pressure? What is the main finding and its importance? The increase in cardiac output during both rowing and running is related to preload to the heart, as indicated by plasma atrial natriuretic peptide, but unrelated to central venous pressure. The results indicate that in upright humans, central venous pressure reflects the gravitational influence on central venous blood rather than preload to the heart.

Abstract: We evaluated the increase in cardiac output (CO) during exercise in relationship to central venous pressure (CVP) and plasma arterial natriuretic peptide (ANP) as expressions of preload to the heart.

Elevated arterial lactate delays recovery of intracellular muscle pH after exercise.

Purpose: We evaluated muscle proton elimination following similar exercise in the same muscle group following two exercise modalities.

Methods: Seven rowers performed handgrip or rowing exercise for ~ 5 min. The intracellular response of the wrist flexor muscles was evaluated by P nuclear magnetic resonance spectroscopy, while arterial and venous forearm blood was collected.

Cardiovascular control during whole body exercise.

It has been considered whether during whole body exercise the increase in cardiac output is large enough to support skeletal muscle blood flow. This review addresses four lines of evidence for a flow limitation to skeletal muscles during whole body exercise. First, even though during exercise the blood flow achieved by the arms is lower than that achieved by the legs (∼160 vs.

Renal lactate elimination is maintained during moderate exercise in humans.

Reduced hepatic lactate elimination initiates blood lactate accumulation during incremental exercise. In this study, we wished to determine whether renal lactate elimination contributes to the initiation of blood lactate accumulation. The renal arterial-to-venous (a-v) lactate difference was determined in nine men during sodium lactate infusion to enhance the evaluation (0.

The intracellular to extracellular proton gradient following maximal whole body exercise and its implication for anaerobic energy production.

Maximal exercise elicits systemic acidosis where venous pH can drop to 6.74 and here we assessed how much lower the intracellular value (pH(i)) might be. The wrist flexor muscles are intensively involved in rowing and (31)P-magnetic resonance spectroscopy allows for calculation of forearm pH(i) and energy metabolites at high time resolution.

Rowing, the ultimate challenge to the human body - implications for physiological variables.

Clinical diagnoses depend on a variety of physiological variables but the full range of these variables is seldom known. With the load placed on the human body during competitive rowing, the physiological range for several variables is illustrated. The extreme work produced during rowing is explained by the seated position and the associated ability to increase venous return and, thus, cardiac output.

Are the arms and legs in competition for cardiac output?

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value.

Cerebral metabolism during upper and lower body exercise.

When continuation of exercise calls for a "will," the cerebral metabolic ratio of O2 to (glucose + lactate) decreases, with the largest reduction (30-50%) at exhaustion. Because a larger effort is required to exercise with the arms than with the legs, we tested the hypothesis that the reduction in the cerebral metabolic ratio would become more pronounced during arm cranking than during leg exercise. The cerebral arterial-venous differences for blood-gas variables, glucose, and lactate were evaluated in two groups of eight subjects during exhaustive arm cranking and leg exercise.

Carotid baroreflex function ceases during vasovagal syncope.

Despite the arterial baroreflex control of heart rate and blood pressure, vasovagal syncope is a common cause of loss of consciousness in people exposed to stimuli that reduce the central blood volume, such as head-up tilt. Carotid baroreflex function was evaluated using a rapid pulse train of neck pressure and neck suction in three conscious volunteers who developed a vasovagal episode during head-up tilt. The maximal gain of the carotid-heart rate and carotid-blood pressure baroreflex function curves were identified as measures of carotid baroreceptor responsiveness.

Brain and central haemodynamics and oxygenation during maximal exercise in humans.

During maximal exercise in humans, fatigue is preceded by reductions in systemic and skeletal muscle blood flow, O(2) delivery and uptake. Here, we examined whether the uptake of O(2) and substrates by the human brain is compromised and whether the fall in stroke volume of the heart underlying the decline in systemic O(2) delivery is related to declining venous return. We measured brain and central haemodynamics and oxygenation in healthy males (n= 13 in 2 studies) performing intense cycling exercise (360 +/- 10 W; mean +/-s.

Carotid baroreflex responsiveness to head-up tilt-induced central hypovolaemia: effect of aerobic fitness.

This investigation examined the interaction between carotid baroreflex (CBR) responsiveness during head-up tilt (HUT)-induced central hypovolaemia and aerobic fitness. Seven average fit (AF) individuals, with a mean maximal oxygen uptake (VO2max) of 49 +/- 1 (ml O2) kg-1 min-1, and seven high fit (HF) individuals, with a VO2max of 61 +/- 1 (ml O2) kg-1 min-1, voluntarily participated in the investigation. After 10-15 min supine, each subject was exposed to nine levels of progressively increasing HUT by 10 deg increments from -20 deg to +60 deg.

Bicarbonate attenuates arterial desaturation during maximal exercise in humans.

The contribution of pH to exercise-induced arterial O2 desaturation was evaluated by intravenous infusion of sodium bicarbonate (Bic, 1 M; 200-350 ml) or an equal volume of saline (Sal; 1 M) at a constant infusion rate during a "2,000-m" maximal ergometer row in five male oarsmen. Blood-gas variables were corrected to the increase in blood temperature from 36.5 +/- 0.

Effects of hyperthermia on cerebral blood flow and metabolism during prolonged exercise in humans.

The development of hyperthermia during prolonged exercise in humans is associated with various changes in the brain, but it is not known whether the cerebral metabolism or the global cerebral blood flow (gCBF) is affected. Eight endurance-trained subjects completed two exercise bouts on a cycle ergometer. The gCBF and cerebral metabolic rates of oxygen, glucose, and lactate were determined with the Kety-Schmidt technique after 15 min of exercise when core temperature was similar across trials, and at the end of exercise, either when subjects remained normothermic (core temperature = 37.