Transcript The Effects of Smoking on Exercise Heat Tolerance

THE EFFECTS OF
SMOKING ON EXERCISE
HEAT TOLERANCE
Druyan Amit
Atias Danit
Muginshtein Jeni
Ketko Itay
Fleishman Chen
Cohen-Sivan Yoav
Yanovich Ran
Helled 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.
60
40
smokers
30
non-smokers
20
10
0
smoking
nicotine
baseline
VO2max ml/kg/min
50
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)
6
P=0.019
P=0.025
5
4
smokers
3
non-smokers
2
1
0
smoking
nicotine
baseline
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.
1200
P=0.049
1000
800
smokers
600
non-smokers
400
200
0
smoking
nicotine
baseline
Sweat Rate gr/hour
P=0.016
Tc during the HTT
Non-smokers
Smokers
P=0.003
P=0.036
HR during the HTT
Non-smokers
Smokers
P=0.043
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