Oxygen desaturation in healthy subjects undergoing the incremental shuttle walk test

OBJECTIVE: To determine the probability of oxygen desaturation in healthy individuals undergoing the incremental shuttle walk test (ISWT). METHODS: We enrolled 83 healthy subjects: 55 males (including 1 smoker) and 28 females. We determined pre-ISWT FEV(1), FEV(6), HR and SpO(2), as well as post-ISWT HR and SpO(2). RESULTS: Mean values overall were as follows: age, 35.05 ± 12.53 years; body mass index, 24.30 ± 3.47 kg/m(2); resting HR, 75.12 ± 12.48 bpm; resting SpO(2), 97.96 ± 1.02%; FEV(1), 3.75 ± 0.81 L; FEV(6), 4.45 ± 0.87 L; FEV(1)/FEV(6) ratio, 0.83 ± 0.08 (no restriction or obstruction); incremental shuttle walk distance, 958.30 ± 146.32 m; post-ISWT HR, 162.41 ± 18.24 bpm; and post-ISWT SpO(2), 96.27 ± 2.21%. In 11 subjects, post-ISWT SpO(2) was higher than was pre-ISWT SpO(2). In 17 subjects, there was a 4% decrease in SpO(2) after the ISWT. There were no statistically significant differences between the groups with and without post-ISWT oxygen desaturation in terms of age, gender, FEV(1), FEV(6), FEV(1)/FEV(6), pre-ISWT SpO(2), incremental shuttle walk distance, HR, or percentage of maximal HR. In the individuals with post-ISWT oxygen desaturation, the body mass index was higher (p = 0.01) and post-ISWT SpO(2) was lower (p = 0.0001). CONCLUSIONS: Healthy individuals can present oxygen desaturation after the ISWT. Using the ISWT to predict subtle respiratory abnormalities can be misleading. In healthy subjects, oxygen desaturation is common after the ISWT, as it is during any intense physical activity.