Immediate Effects of Smoking on Cardiorespiratory Responses During Dynamic Exercise: Arm Vs. Leg Ergometry

TL;DR

In a randomized crossover trial of 14 young male smokers, smoking two cigarettes immediately reduced pulmonary function and heart rate variability and impaired leg-cycling exercise performance more than arm-cranking performance. The negative effects on arm exercise were not as pronounced, with no significant smoking-related change in arm time to exhaustion.

Key findings

• Five minutes after smoking, FVC (P = 0.003), FEV1 (P = 0.033), and PEF (P = 0.013) decreased, and resting heart rate increased (P < 0.001).
• HRV decreased after smoking: R-R interval fell from 712.73 ± 93.06 to 622.29 ± 103.82 ms (P = 0.001), total power from 7.59 ± 0.72 to 6.79 ± 1.00 ln(ms²) (P = 0.014), LF from 7.03 ± 0.79 to 6.27 ± 1.08 ln(ms²) (P = 0.026), and HF from 5.25 ± 0.83 to 4.38 ± 1.33 ln(ms²) (P = 0.028).
• In leg cycling, smoking reduced peak power (P = 0.005) and time to exhaustion (P = 0.005); at the ventilatory threshold, VO2 (P = 0.002), VE (P < 0.001), heart rate (P = 0.038), and RER (P = 0.048) were lower in the smoking trial.
• In arm cranking, peak power was lower after smoking (P = 0.036), but time to exhaustion did not differ significantly (P = 0.098); no significant smoking effects were observed for arm VO2, VE, RER, or workload at the ventilatory threshold.

Methods

• Randomized crossover design: 16 moderately trained male smokers initially volunteered, 14 completed all sessions (mean age 20.4 ± 1.5 years; smoking duration 4.0 ± 2.0 years; 9.9 ± 2.9 cigarettes/day).
• Each participant completed four sessions: control trials after refraining from smoking for at least 8 h, and experimental trials after smoking two cigarettes (10 mg tar and 0.7 mg nicotine each) immediately before arm-cranking and leg-cycling graded exercise tests to exhaustion.
• Pulmonary function and HRV were measured before and after smoking; exercise outcomes included peak power, time to exhaustion, ventilatory threshold, and VO2, heart rate, and VE calculated at every 10% increment of maximal effort time. Paired t-tests and repeated-measures MANOVA with trend analysis were used.

Limitations

• Stated: the study investigated immediate smoking responses in moderately trained people during maximal arm and leg exercise and cannot determine the impact of smoking on arm aerobic performance in elite athletes.
• Evident: the final sample was small (n = 14), all male, young, and regular smokers, limiting generalizability to women, older adults, non-smokers, or other training levels.
• Evident: the authors note that muscle glycogen and lactate concentrations were not measured, so proposed mechanisms related to substrate use remain indirect.