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Titolo:
Short-term cardiovascular responses to rapid whole-body tilting during exercise
Autore:
Sundblad, P; Haruna, Y; Tedner, B; Linnarsson, D;
Indirizzi:
Karolinska Inst, Dept Physiol & Pharmacol, Sect Environm Physiol, SE-17177Stockholm, Sweden Karolinska Inst Stockholm Sweden SE-17177 iol, SE-17177Stockholm, Sweden Natl Inst Vocat Rehabil, Disabil Res Div, Mihama Ku, Chiba, Japan Natl Inst Vocat Rehabil Chiba Japan il Res Div, Mihama Ku, Chiba, Japan
Titolo Testata:
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 4, volume: 81, anno: 2000,
pagine: 259 - 270
SICI:
1439-6319(200003)81:4<259:SCRTRW>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
HEAVY RHYTHMIC EXERCISE; DYNAMIC EXERCISE; CAROTID BAROREFLEX; BLOOD-FLOW; MUSCLE PUMP; HEART-RATE; PRESSURE; HUMANS; RESPIRATION; CONDUCTANCE;
Keywords:
leg exercise; posture; blood pressure; heart rate; cardiovascular model;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: Sundblad, P Karolinska Inst, Dept Physiol & Pharmacol, Sect Environm Physiol, SE-17177Stockholm, Sweden Karolinska Inst Stockholm Sweden SE-17177 7Stockholm, Sweden
Citazione:
P. Sundblad et al., "Short-term cardiovascular responses to rapid whole-body tilting during exercise", EUR J A PHY, 81(4), 2000, pp. 259-270

Abstract

Our objective was to characterize the responses of heart rate (HR) and arterial blood pressure (BP) to changes in posture during concomitant dynamic leg exercise. Ten men performed dynamic leg exercise at 50, 100, and 150 W and were rapidly and repeatedly tilted between supine (0 degrees) and upright (80 degrees) positions at 2-min intervals. Continuous recordings of BP and HR were made, and changes in central blood volume were estimated from transthoracic impedance. Short-lasting increases in BP were observed immediately upon tilting from the upright to the supine position (down-tilt), averaging +18 mmHg (50 W) to +31 mmHg (150 W), and there were equally short-lasting decreases in BP, ranging from -26 to -38 mmHg upon tilting from supine to upright (up-tilt). These components occurred for all pressure parameters(systolic, mean, diastolic, and pulse pressures). We propose that these transients reflect mainly tilt-induced changes;in total peripheral resistanceresulting from decreases and increases of the efficiency of the venous muscle pump. After 3-4 s (down-tilt) and 7-11 s (up-tilt) there were large HR transients in a direction opposite to the pressure transients. These HR transients were larger during the down-tilt (-15 to -26 beats . min(-1)) than during the up-tilt (+13 to +17 beats . min(-1)), and increased in amplitudewith work intensity during the down-tilt. The tilt-induced HR fluctuationscould be modelled as a basically linear function of an arterial baroreflexinput from a site halfway between the heart and the carotid sinus, and with varying contributions of fast vagal and slow sympathetic HR responses resulting in attenuated tachycardic responses to hypotensive stimuli during exercise.

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Documento generato il 03/12/20 alle ore 12:23:35