Cold exposure attenuates post exercise cardiovagal reactivation and sympathetic withdrawal

In a crossover design we investigated cardiac autonomic responses (heart rate variability, HRV) to isometric handgrip exercise (IHG) in cold (4. °C) and temperate (24. °C, temp) conditions in 20 men that assumed the supine position for 30. min in an environmental chamber. After a 5. min rest, subjects performed 3. min of IHG followed by a 3. min recovery period (REC). During REC, the low frequency of HRV was lower while the high frequency and the square root of the mean squared differences of successive NN intervals were higher (. P<. 0.05) than the rest in the temp compared to a full recovery in the cold. In conclusion, recovery from concurrent cold exposure and exercise impairs cardiovagal modulation which may precipitate cardiac events.