The Effects of Smoking on Exercise Heat Tolerance

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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

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• 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

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• 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 1980s.

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Cigarettes active ingredients

• Carbon Monoxide (CO)
• Higher affinity to HB than O2 (X200) gtgt decreases
  O2 carrying capacity.
• Decreases O2 dissociation in the muscle tissues.
• gtgt relative hypoxia in the muscle tissue gtgt
  lower Vo2 max

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Cigarettes active ingredients

• Tar
• Increases Endothelin-1 (a vasoconstrictant)
• Decreases NO release (a vasodilator)
• gtgt Negative effect on vasodilation

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Cigarettes active ingredients

• Nicotine
• Smoking 1 cigarette delivers 1-2 mg of nicotine
  to the smoker
• Increases blood Cathecholamines (increases
  sympathetic activity) -gt increases HR,
  peripheral vasoconstriction, BP.
• Increases sympathetic activity and increases RMR.

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Cigarettes active ingredients

• Nicotine
• Chronic nicotine ingestion gtgt beta adrenergic
  receptors down-regulationgtgt lower use of fatty
  acids and higher dependence on glucose (prolonged
  exercise?)
• Increases platelets aggregationgtgt elevates blood
  viscosity.
• Increases Vasopressin, ß-endorphin, ACTH,
  Cortisol, GH and Prolactin

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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.

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Cigarettes Effect on physical performance

• Lower tolerance for prolonged aerobic physical
  activity gtgt 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)

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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.

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Exertional Heat Stroke risk facrots
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Study goals

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

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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).

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Fitness (VO2max) test

• No baseline changes between smokers and
  non-smokers
• No significant change after nicotine ingestion or
  smoking in both groups.

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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)

P0.025
P0.019
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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.

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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.

P0.049
P0.016
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Tc during the HTT
Non-smokers
P0.003
Smokers
P0.036
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HR during the HTT
Non-smokers
Smokers
P0.043
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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.

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