Smoking status and physical fitness during initial military training

Background: Habitual smoking is prevalent in military populations, but
whether smoking status influences physical fitness development during training is
not clear.

Aims: We investigated the effect of smoking status on physical fitness
parameters during initial British Army Infantry training.

Methods: Routine measures of physical fitness (2.4 km run time and
maximum number of press ups and sit ups in two minutes) were obtained in 1,182
male recruits (mean ± SD: age 20 ± 3 y, body mass 70.6 ± 9.8 kg, height 1.77 ± 0.07
m; 58% smokers) at weeks 1, 14 and 24 of initial military training. A linear mixed
model was used to identify differences in performance between smokers and nonsmokers over time.

Results: Non-smokers performed significantly better than smokers in all
performance tests (P<0.01), but rates of improvement during training were similar
(P>0.05). Run performance improved by 7% in non-smokers (estimated marginal
means with 95% confidence limits; 612 (608-616) s to 567 (562-572) s) and 8% in
smokers (622 (619-625) s to 571 (568-575) s). Press up performance improved by
18% in non-smokers (48.3 (47.1-49.4) to 57.0 (55.6-58.3)) and 23% in smokers (44.1
(43.2-45.1) to 54.5 (53.3-55.6)) and sit up performance by 15% in non-smokers (57.3
(56.3-58.2) to 66.0 (64.9-67.2)) and 18% in smokers (53.8 (53.0-54.6) to 63.3 (62.3-
64.3)).

Conclusions: Smokers exhibited lower muscular and cardiorespiratory
endurance performance than non-smokers. Unexpectedly however, no significant
differences in improvement in performance indices were demonstrated between
smokers and non-smokers during military training.