1. 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

2. 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

3. 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.

6. 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

7. Cigarettes – active ingredients
Tar
Increases Endothelin-1 (a vasoconstrictant)
Decreases NO release (a vasodilator)
>> Negative effect on vasodilation

8. 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.

9. 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

10. 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.

11. 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)

12. 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.

13. Exertional Heat Stroke risk facrots

14. Study goals
To examine the effect of acute smoking and nicotine ingestion on physical performance and exercise heat tolerance.

15. 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).

16. Fitness (VO2max) test
No baseline changes between smokers and non-smokers
No significant change after nicotine ingestion or smoking in both groups.

17. 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=0.019
P=0.025

18. 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.

19. 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=0.016
P=0.049

20. Tc during the HTT
Non-smokers
Smokers
P=0.003
P=0.036

21. HR during the HTT
Non-smokers
Smokers
P=0.043

23. 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.

24. 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