Changes in sympathetic nervous system activity in male smokers after moderate-intensity exercise.

OBJECTIVE To investigate the effects of moderate-intensity exercise on the sympathetic nervous system in male smokers. METHODS Twenty-eight men (14 smokers and 14 non-smokers, ages 21-46 y) were recruited. The activity of the autonomic nervous system was measured by power spectral analysis of heart rate variability. Spectral power in the frequency domain was quantified by integrating the area under the curve of the very-low-frequency power (0.007-0.035 Hz), low-frequency power (0.035-0.15 Hz), high-frequency power (0.15-0.5 Hz), and total power (0.007-0.5 Hz) bandwidths. We assessed heart rate, thermoregulatory sympathetic nervous system activity (very-low-frequency power/total power), sympathetic nervous system activity (low-frequency-power/high-frequency power or [very-low-frequency power + low-frequency power]/high-frequency power), and parasympathetic nervous system activity (high-frequency power/total power) of the smokers before and after moderate-intensity exercise. RESULTS The smokers exhibited a greater degree of sympathetic nervous system activity (as quantified by very-low-frequency power/total power). The sympathetic nervous system activity of smokers (as indicated by [very-low-frequency power + low-frequency power]/high-frequency power) also showed a tendency to increase after exercise. Parasympathetic activity, as indicated by high-frequency power/total power, reduced after exercise in the smokers. These findings are contrary to findings previously reported in obese subjects. CONCLUSIONS Increased sympathetic nervous system activity, including thermoregulatory activity, might contribute to cachexia in smokers.