THE EFFECTS OF SMOKING ON EXERCISE HEAT TOLERANCEDruyan AmitAtias DanitMuginshtein JeniKetko ItayFleishman ChenCohen-Sivan YoavYanovich RanHelled Yuval
• Cigarette smoking is the leading preventable cause of mortality.
• Nicotine abuse is the most common substance abuse in the world.
• Smokers who stop smoking reduce their risk of developing and dying from tobacco-related diseases
• Smoking amongst soldiers decreases physical fitness• Smoking increases clinic visits and sick leaves among
soldiers.• Smokers succeed less during basic training• In the US army smoking was forbidden during basic
training in the 1980’s.
Cigarettes – active ingredients
Carbon Monoxide (CO)•Higher affinity to HB than O2 (X200) >> decreases O2 carrying capacity.•Decreases O2 dissociation in the muscle tissues.
>> relative hypoxia in the muscle tissue >> lower Vo2 max
Cigarettes – active ingredients
Tar•Increases Endothelin-1 (a vasoconstrictant)•Decreases NO release (a vasodilator)
>> Negative effect on vasodilation
Cigarettes – active ingredients
Nicotine•Smoking 1 cigarette delivers 1-2 mg of nicotine to the smoker•Increases blood Cathecholamines (increases sympathetic activity) -> increases: HR, peripheral vasoconstriction, BP.•Increases sympathetic activity and increases RMR.
Cigarettes – active ingredients
Nicotine•Chronic nicotine ingestion >> beta adrenergic receptors down-regulation>> lower use of fatty acids and higher dependence on glucose (prolonged exercise?)•Increases platelets aggregation>> elevates blood viscosity.•Increases Vasopressin, β-endorphin, ACTH, Cortisol, GH and Prolactin
Cigarettes – active ingredients
Nicotine•Toxic to Osteoblasts, Fibroblasts, Macrophages and causes endothelial damage.•Increases the sweat rate, m/p by sympathetic acticity.•Causes de-sensitization and up-regulation of nAChRs, thus response to nicotine is different between smokers and non-smokers.
Cigarettes – Effect on physical performance• Lower tolerance for prolonged aerobic physical
activity >> smokers report earlier exhaustion, dyspnea, muscle pain
• Young healthy smokers and non-smokers have similar aerobic fitness.
• Acute smoking decreases VO2max after smoking a cigarette.
• Smoking increases RMR (smoking 4 cigarettes increases RMR by 33% for 3 hours)
Cigarettes – Effect on physical performance• Nicotine doubles energy expenditure during physical
activity compared with its resting effect.• Smoking increases the sweat rate during and after
smoking.• Smoking decreases cutaneous blood flow.• Smokers have decreased micro-vascular vasomotor
function compared to non-smokers.
Exertional Heat Stroke risk facrots
Study goals• To examine the effect of acute smoking and nicotine
ingestion on physical performance and exercise heat tolerance.
Study design• 16 young healthy male subjects, 8 smokers & 8 non-
smokers.• HRV measurement, VO2max test, HTT – after 12 hours of
abstinence, after nicotine ingestion (2 mg lozenges), for the smokers after smoking (2 0.8mg nicotine containing cigarettes).
Fitness (VO2max) test• No baseline changes between smokers and non-smokers• No significant change after nicotine ingestion or smoking
in both groups.
Heart Rate Variability (HRV)• Non-smokers did not react to nicotine• In smokers the LF/HF ratio increased after nicotine
ingestion and smoking (increased sympathetic tone)
P=0.025P=0.019
Heat Intolerance• 2 out of 8 smokers were found heat intolerant during the
baseline HTT.• All non-smokers were found heat tolerant during the
baseline HTT.
Sweat Rate during the HTT• No baseline changes between smokers and non-smokers• Both nicotine ingestion and smoking increased SR in
smokers. Nicotine did not increase SR in non-smokers.
P=0.049P=0.016
Tc during the HTT
P=0.003
P=0.036
Non-smokers
Smokers
HR during the HTT
P=0.043
Non-smokers
Smokers
Conclusions• Acute smoking and nicotine ingestion increase the
physiological strain during an exercise heat challenge, thus may be considered as risk factors for heat injuries.
• The sympathetic activation of nicotine which causes peripheral vasoconstriction probably plays a major role in the increased physiological strain.
סא"ל פרופ' יובל חלד
רס"ן דר' רן ינוביץ'
רס"ן חן פליישמן
סרן (מיל') דר' יואב כהן-סיון
דר' דנית אטיאס
סרן ג'ני מוגינשטיין
סרן איתי קטקו
סמל ליאור כגן
רב"ט אמיר פרגמן