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Humans react to cold with various symptoms. Previous studies enquiring about symptoms during cold exposure have for the most part been population based studies using questionnaries and have focused on a narrow spectrum of symptoms. The purpose of this study was to study the effect of cold air and physical exercise on a wide range of symptoms in healthy individuals.

A total of 31 healthy subjects were experimentally exposed to +10 °C and -10 °C in an environmental chamber for one hour, on two separate occasions. During each exposure, subjects performed an intermittent moderate-intensity running protocol between 62-78% of maximal oxygen consumption (VO2 max). At five timepoints, before, during and after the exposures, subjects were asked about 18 symptoms and their intensity. The Borg CR10 scale was used to rate the intensity from 0 to 11, where 0 meant "none" and 11 meant "maximal". The sum of all five Borg CR10-scores were added together to form a single score for each exposure. Paired Wilcoxon signed-rank test was used for analysis. Data are presented as medians.

Symptoms of cough, eye irritation, physical discomfort, and cold extremities were present only at -10 °C. Compared to exercise in +10 °C, exercise in -10 °C induced significantly higher summed symptom scores for eye irritation 2.0 vs 0.5 (p=0.011), rhinitis 12.0 vs 8.0 (p=0.000), nasal irritation 3.5 vs 0.5 (p=0.001), cold face 7.0 vs 1.0 (p=0.000), physical discomfort 6.5 vs 0.0 (p=0.000), and cold extremities 10.0 vs 0.5 (p=0.000).

In healthy subjects, moderate-intensity exercise in -10 °C can induce and enhance the intensity of a wide range of symptoms. Symptoms of the lower airways were infrequent and mild.