REF-1456 · Klausen et al., 1983 · European Journal of Applied Physiology and Occupational Physiology · Paper · PubMed

Does a cigarette before a hard session cost anything?

In 16 men, the smoke of 3 cigarettes cut VO2max about 7% and time at VO2max 20%; CO alone 7% and 10%. Fitness not stated, 1983, from the abstract.

Main caveat: Abstract only, and truncated in the record at 250 words; no COHb value, SDs or timing.
limited evidenceMeasured on non-athletes and recreational people

Klausen and colleagues asked what a few cigarettes cost at maximal exercise, and which part of that cost is carbon monoxide. Sixteen men were tested in the morning after about 8 h without smoking, after inhaling the smoke of three cigarettes, and after inhaling an amount of CO that gave the same CO saturation of the arterial blood as smoking.

VO2max fell by about 7% with both smoke and CO. Endurance time at VO2max fell 20% after smoke but only 10% after CO. Maximal heart rate fell and resting heart rate rose only after smoke, and peak lactate after maximal exercise was lower after smoke.

The authors read the VO2max loss as CO lowering the oxygen capacity of the blood, and the larger endurance loss as CO plus an increased cost of breathing from smoke particles; they suggest nicotine or another smoke component acts on the heart, raising it at rest and inhibiting it at maximal exercise.

Our reading: this is the only study in the base that separates the two costs of a cigarette in one design, and it is old, small and known to us only from a truncated abstract. The abstract does not describe trained endurance athletes, and the study does not test threshold work or say how long the effect lasts.

Protocol

Participants: n = 16 men; age, fitness and smoking history are not in the abstract.
Conditions: (1) after about 8 h without smoking (control); (2) after inhaling the smoke of three cigarettes; (3) after CO inhalation giving the same CO saturation of the arterial blood as smoking. Order and spacing are not in the abstract; blinding is not mentioned and smoke cannot be blinded against CO.
Test: rest and maximal exercise on a Krogh cycle ergometer, in the morning.
Outcomes: VO2max, endurance time at VO2max, heart rate at rest and at maximum, peak lactate.
Funding and interests: PubMed lists non-US government support; no funder or conflict statement in the record.

Key Results

Outcome, against controlSmoke of 3 cigarettesCO to the same saturation
VO2maxabout −7%about −7%
Endurance time at VO2max−20%−10%
Maximal heart ratesignificantly lowernot reported as changed
Resting heart ratehighernot reported as changed
Peak lactate after maximal exercisesignificantly lowernot reported as changed
Not in the abstract: the COHb reached, SDs or confidence intervals, absolute VO2max, the time between smoking and the test. The record cuts off at 250 words.

Mechanisms

Measured: equal VO2max loss with smoke and with matched CO; twice the endurance loss with smoke as with CO; heart-rate changes only with smoke.
Authors' interpretation: the VO2max loss is due to CO saturation lowering the oxygen capacity of the blood; the endurance loss combines CO saturation and an increased cost of breathing caused by smoke particles; nicotine or another smoke component enhances the heart at rest and inhibits it at maximal exercise.
Inference: VO2max is delivery-limited in whole-body exercise (PHYS-09, established), so less oxygen carried per gram of haemoglobin fits the VO2max result. The breathing-cost and nicotine readings were not measured directly in what the abstract reports.

Practical Application

Does a cigarette before a hard session cost anything? In 16 men, the smoke of 3 cigarettes cut VO2max about 7% and time at VO2max 20%; CO alone 7% and 10%. Fitness not stated, 1983, from the abstract.
What it separates: smoke costs more than its CO alone in this test, so a product without CO would not automatically be free of cost, and removing CO is not the same as removing the airway effect (REF-1463, REF-1473). That is an inference across entries; no product other than cigarettes was tested here.
Hours before a session: this paper gives no window. Not from this paper; the base's own practice: any hour rule is practice built on half-lives and does not carry this entry's level.
Heart rate on the day: resting heart rate up and maximal heart rate down after smoke mean a smoker's numbers on that day are not comparable with a smoke-free day (PHYS-12); the abstract gives no bpm.
What it does not show: anything in trained endurance athletes, at threshold or over long efforts, in women, or after one cigarette; how long the effect lasts; whether habitual smokers differ from others.

Limitations

Abstract only, and truncated in the record at 250 words; no COHb value, SDs or timing.
Who was measured: 16 men of unstated fitness; not trained endurance athletes as far as the abstract shows.
Design details missing: order of conditions and blinding are not stated; a learning or fatigue order effect cannot be ruled out from the abstract.
Control is short abstinence: after about 8 h some CO from earlier smoking may remain, so the contrast may understate the cost; this is our inference.
Old (1983) and a single laboratory; a test to exhaustion at VO2max, not a race.
Funding and interests: non-US government support per PubMed; no statement in the record.
How this entry was checked and changed
Why this level

(from the abstract) — three within-subject conditions in at least 15 participants with a performance outcome could reach the rubric's B+ as a controlled crossover, held one step down: the abstract is truncated at 250 words in PubMed, does not call it a crossover, and gives no order of conditions, no COHb value and no fitness data