title: Immediate Effects of Smoking on Cardiorespiratory Responses During Dynamic Exercise: Arm Vs. Leg Ergometry.
abstract: OBJECTIVE
  This study compared the immediate effects of smoking on cardiorespiratory responses to dynamic arm and leg exercises.
  
  
  METHODS
  This randomized crossover study recruited 14 college students. Each participant underwent two sets of arm-cranking (AC) and leg-cycling (LC) exercise tests. The testing sequences of the control trial (participants refrained from smoking for 8 h before testing) and the experimental trial (participants smoked two cigarettes immediately before testing) were randomly chosen. We observed immediate changes in pulmonary function and heart rate variability after smoking and before the exercise test. The participants then underwent graded exercise tests of their arms and legs until reaching exhaustion. We compared the peak work achieved and time to exhaustion during the exercise tests with various cardiorespiratory indices [i.e., heart rate, oxygen consumption (VO2), minute ventilation (VE)]. The differences between the smoking and control trials were calculated using paired t-tests. For the exercise test periods, VO2, heart rate, and VE values were calculated at every 10% increment of the maximal effort time. The main effects of the time and trial, as well as their trial-by-time (4 × 10) interaction effects on the outcome measures, were investigated using repeated measure ANOVA with trend analysis.
  
  
  RESULTS
  5 min after smoking, the participants exhibited reduced forced vital capacities and forced expiratory volumes in the first second (P < 0.05), in addition to elevated resting heart rates (P < 0.001). The high-frequency, low-frequency, and the total power of the heart rate variability were also reduced (P < 0.05) at rest. For the exercise test periods, smoking reduced the time to exhaustion (P = 0.005) and the ventilatory threshold (P < 0.05) in the LC tests, whereas no significant effects were observed in the AC tests. A trend analysis revealed a significant trial-by-time interaction effect for heart rate, VO2, and VE during the graded exercise test (all P < 0.001). Lower VO2 and VE levels were exhibited in the exercise response of the smoking trial than in those of the control LC trials, whereas no discernable inter-trial difference was observed in the AC trials. Moreover, the differences in heart rate and VE response between the LC and AC exercises were significantly smaller after the participants smoked.
  
  
  CONCLUSIONS
  This study verified that smoking significantly decreased performance and cardiorespiratory responses to leg exercises. However, the negative effects of smoking on arm exercise performance were not as pronounced.
authors.affiliation: Department of Physical Therapy, I-Shou University Kaohsiung, Taiwan.
authors.forename: Chien-Liang
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Department of Nursing, Chung-Hwa University of Medical Technology Tainan, Taiwan ; Institute of Allied Health Sciences, National Cheng Kung University Tainan, Taiwan.
authors.forename: Jing-Shia
authors.initials: JS
authors.lastname: Tang
authors.affiliation: Department of Occupational Therapy, I-Shou University Kaohsiung, Taiwan.
authors.forename: Ping-Chia
authors.initials: PC
authors.lastname: Li
authors.affiliation: School of Nursing, Kaohsiung Medical University Kaohsiung, Taiwan.
authors.forename: Pi-Ling
authors.initials: PL
authors.lastname: Chou
keywords: acute effect; aerobic exercise; cardiopulmonary exercise test; cigarette smoke; cycling ergometry; heart rate variability; pulmonary function test