METABOLIC RESPONSES TO EXERCISE AND HEALTH BENEFITS OF PHYSICAL ACTIVITY

Tampere, Finland www.ukkinstituutti.fi Sauna bathing & cardiovascular diseases Katriina Kukkonen-Harjula, MD for Health Promotion Research Themes • acute cardiovascular responses to heat healthy & w/ CVD • therapeutic effects of sauna bathing in CVD new: congestive heart failure endothelial dysfunction • cardiovascular risks of bathing in CVD not discussed - cardiovascular drugs - cold water immersion (winter swimming) - children General physiological response to sauna Heat Skin receptors Venules Arterioles Thermoregulatory centers Sympathetic nervous system Endocrine glands Several effects Sweat glands Lungs Metabolism Heart (Vuori 1992) Circulatory responses to heat (supine) n=7-17 men, directly whole-body heated 30-53’ (Rowell LB, Physiol Rev 1983;52:368) Redistribution of CO (supine) Hot = severe hypertermia Tc > 39° (Rowell 1983. Handb. Physiol. Sect 2, vol III, ch 27, p 967. Am Physiol Soc) Acute cardiovascular responses Skin blood flow Blood flow from 5..10% up to 50-70% CO from 0.5 to 7 l/min renal by 0.4 l/min to int. organs Blood flow to muscles Heart rate splanchnic 0.6 by 0.2 l/min up to 100 bpm (moderate; accust.) up to 150 bpm (intense, unaccust.) Cardiac output Stroke volume Systolic pressure from 5-6 l/min up to 9-10 l/min Diastolic pressure (Hannuksela & Ellahham 2001) Effects of sauna on cardiac load & myocardial oxygen demand Heat Heart Volume work -skin blood flow -blood flow to intern. organs, muscles O2 demand RPP Pressure work vasodilation vasc. resistance Small risk of insuff. oxygenation pump function (Vuori 1992) Heart rate healthy (Kukkonen-Harjula et al. 1989) (Kukkonen-Harjula et al. 1989) (pmol x ml-1) 8 Plasma noradrenaline & adrenaline NA *** A 6 *** *** *** ** ** 4 *** 2 * 0 NA A NA A NA A NA Rest A 1st 2nd exposure 100°(dry heat) Post-sauna cooling 80°(dry & humid heat) 80°(dry heat) (Kukkonen-Harjula et al. 1989) Sauna, alcohol & heart Roine et al. (1992) 10 healthy men alcohol  sauna  sleep  sauna (hangover) • heavy drinking does not provoke dysrhythmias in healthy persons continuous ECG 18 h • alcoh. SBP after bathing • does bathing alleviate hangover ? Blood pressure (mmHg) 180 160 140 120 100 Systolic juice alcohol * Diastolic 80 60 20 0 1 Drinking Sauna 4 Sauna 15 16 17 2 3 Time (h) (Roine et al. 1992, modified) Therapeutic effects of sauna • coronary heart disease arterial hypertension cardiac failure peripheral arterial disease • research problems study design: RCT blinding? cointerventions drugs, invasive cardiology habituation to bathing Coronary heart disease • coronary patients tolerate sauna well in stable medicated state favourable vasodilation induced by heat decreases cardiac load myocardial O2 demand ~ RPP more angina & dysrhythmia during X-test than sauna, at same HR • orthostatism (Eisalo & Luurila 1988) Bathing habits & symptoms 10 y after myocardial infarction Finnish patients (N=61) (Eisalo & Luurila, Ann Clin Res 1988;20:267) Cardiovascular risks of sauna bathing sudden (cardiovascular) death • pre-existing coronary disease often undiagnosed + alcohol • risk is lower in sauna bathing than in other daily chores **** accidents (drowning, burns) Arterial hypertension • post-sauna vasodilation  hypotension • bathing OK in controlled hypertension • sauna bathing as nonpharmacological therapy in mild hypertension ? vs. weight, sodium, alcohol reduction physical activity (Sanner et al. 1993 Siewert et al. 1994) Vascular endothelial dysfunction • infrared dry heat 60°15 min, supine deep body temp. +1° followed by bed rest w/ blanket, 30 min • 25 men with CHD risk factors, ~38 y 60°15 min, 5 x /week, 2 wk & 10 healthy persons (baseline assessment only) • endothelial function test - endothelium-dependent vasodilator response is a surrogate for bioavailability of NO - brachial arterial diameter; FMD after reactive hyperemia, ultrasound endothelial dysfunction is an early stage of atheroscler. (Imamura et al. 2001) Brachial artery blood flow n=8 patients blood flow  shear stress  eNOS activity warm ’cool-off’ (Imamura M, J Am Coll Cardiol 2001;38:1083) Endothelial dysfunction Flow-mediated dilation in persons with CHD risk factors no change in arterial diameter react. hyperemia %NTG %FMD in healthy 8.2 (Imamura M, J Am Coll Cardiol 2001;38:1083) Congestive heart failure (CHF) • infrared dry heat 60° 15 min, supine • acute effects (Tei 1995) improved hemodynamics reduction of cardiac preload & afterload • repeated heat exposure in animals & humans thermal vasodilation improves vascular endothelial dysfunction of CHF cardiac function symptoms (Tei et al., Japan) Congestive heart failure & infrared heat repeated heat exposure in animals - upregulation of endothelial NO synthase expr. healthy hamsters, 4 wk (Ikeda 2001) (Ikeda 2002) - improved survival hamsters w/ CHF - increased eNOS mRNA expression in aorta - upregulation of aortic eNOS protein expression CMP hamsters (Ikeda 2005) - induction of angiogenesis via eNOS mice w/ hindlimb ischemia, 5 wk (Akasaki 2006) (Tei et al., Japan) Congestive heart failure - repeated infrared heat (60°) in humans controlled, nonrandomized 20 patients + 10 matched controls w/ CHF 2 wk FMD BNP NTG ANP EF (Kihara et al. 2002) Relation of flow-mediated dilation & brain natriuretic peptide (Kihara T, J Am Coll Cardiol 2002;39:754) Congestive heart failure - repeated infrared heat (60°) • noncontrolled (pre-post) 15 patients w/ systolic heart failure 60° infrared dry heat, sitting; 4 wk • symptoms improved; NYHA • exercise tolerance improved 6-min walking dist. 388  448 m • EF BNP (Miyamoto et al. 2005) Congestive heart failure - repeated infrared heat (60°) RCT 30 patients, NYHA III/II dilated & ischemic cardiomyopathy w/ ventric. arrhythmia 5 d/wk, 2 wk HR variability PVC symptoms & NYHA improved LVEF, BP, catecholamines (Kihara et al. 2004) Peripheral arterial disease - repeated infrared heat (60°) • n=1, severe disease; 15 wk • increased angiogenesis collaterals in angiography NO is a mediator of angiogenesis improved critical limb ischemia (Tei et al. 2006) Cardiovascular contraindications to sauna bathing • myocardial infarction / other severe cardiac event 4-8 wk pause 2-3 wk after minor events (no complications) • unstable / prolonged angina pectoris (acute) • severe aortic stenosis • other severe cardio/cerebrovascular diseases decompensated cardiac failure stroke, TIA – unstable stage severe orthostatic hypotension dysrhythmias Bathing advive to CVD patients • < 90°; supine vs. sitting position • avoid rapid extreme temperature changes cooling • cool-off • avoid alcohol & heavy meals before/during bathing • non-alcohol fluid compensation • habituation Conclusions - sauna bathing causes short, intense heat exposure - during recovery, physiological responses to heat are fast returned to resting baseline - cardiovascular diseases when stable & medicated pose no problems hypertension, coron. heart dis., congest. heart failure - therapeutic use of sauna bathing in CVD requires further RCT’s congest. heart failure, periph. art. disease 60° vs. 80-100° ? habituation to bathing REVIEW Kukkonen-Harjula K & Kauppinen K. Health effects and risks of sauna bathing. Int J Circumpolar Health 2006; 65 (3); 195-205 http://ijch.oulu.fi Combat mechanisms of the body against heat stress cutaneous vasodilation skin blood flow cardiac output flow to internal organs Blood pressure (mmHg) 180 160 140 120 Systolic Juice Alcohol 100 80 60 Diastolic 20 0 1 Drinking 2 Sauna 3 4 Sauna 15 16 17 Time (h) (Roine et al. 1992, modified) Circulatory responses to sauna bathing Heat Sympathetic nervous system Blood vessels, skin vasodilation flow x20 – 40 resistance Blood vessels, int. organs constriction flow HR CO ad max 75–100% Blood pressure systolic + diastolic + (Vuori 1992) Effects of intensive cooling after sauna Heat Cold Vasodilation, skin Sudden vasoconstriction  Blood pressure Blood return to lungs dyspnea heart risk of dysrhythmia pump failure O2 lack (Vuori 1992) Hormonal responses to sauna bathing Sauna CNS Hypothalamus Sweating Cardiovascular pressure-, volume- & osmoreceptors Sympathetic nervous system Hypophysis Posterior Anterior ADH Kidney Renin Angiotensin II Prolactin GH ACTH β-endorphin Adrenals Cortex Medulla Aldosterone Cortisol Noradrenaline Adrenaline (Kukkonen-Harjula & Kauppinen 1988) (Kukkonen-Harjula et al. 1989) (ng/ml) 250 Serum thromboxane B2 200 100 50 0 Rest 1st 2nd exposure Post-sauna cooling 80°(dry & humid heat) (Kukkonen-Harjula et al. 1989) 80°(dry heat) 100°(dry heat) Plasma 6-ketoprostaglandin F1α 6-k-PgF1α (Vähä-Eskeli K, Eur J Obstet Gynecol Reprod Biol 1992;43:97) Plasma thromboxane B2 TxB2 (Vähä-Eskeli K, Eur J Obstet Gynecol Reprod Biol 1992;43:97)