Background / Objective: Six Minute Walk Test (6-MWT) is a popular and widely accepted modality of objective evaluation of functional exercise capacity as it is inexpensive and simple to perform. Despite the popularity of the 6MWT in the clinical setting, there is a paucity of 6MWD reference values obtained in healthy subjects. This limits the interpretation of 6MWD in patients and poses problems for clinicians wishing to provide patients with a measure of their expected 6MWD in the absence of disease.

Recent studies have established regression equations to predict the six minute walking distance (6-MWD) in healthy Caucasians, Asians and North Africans; however, regression equations have not be established for the Nigerian population.

This study was therefore aimed to determine 6-MWD in apparently healthy Nigerian population, determine cardiovascular response to 6MWT in this population, identify factors contributing to 6MWD and compare measured 6MWD with predicted 6MWD from existing reference equations derived from Caucasian, Asian and North African subjects .

Materials and Method: 68 apparently healthy subjects (43males, 25 females) with no history of cardiovascular or musculoskeletal disorders participated in the study. ATS standardized 6-MWT method was used, cardiovascular parameters (systolic, diastolic blood pressures, heart rate and respiratory rate) were taken before and after the test and also the anthropometric parameters (height, weight) and age were taken. Subjects were interviewed about their medical history and medication used before they were included in the study. All data was analysed using SPSS package (version 17.0). Data are reported as mean ± SD. An alpha value of 0.05 was used to determine the level of significance.

Results: The mean age of the subjects was 39 ± 11.4years and 41 ± 8.7 years for both male and female respectively. The mean height, weight and BMI of males were 1.71±0.08m, 70 ±12.5kg, 3.7±3.4kg/m² and that of females were 1.62±0.05m, 74±13.5kg, 28±4.8kg/m².

The male subjects had a 13.8% increase in heart rate while the female subjects had a 19.8% increase. The male subjects had 17.3% and 15.6% increase in SBP and DBP respectively while the female subjects had 15% and 11% increase in SBP and DBP. The male and female subjects had a 28.3% and 29.5% increase in respiratory rate respectively.

The distance covered in six minutes by the subjects was 528±58.5 and 499.9±53.2 for male and female respectively.

The resulting gender-specific regression equations in the distance walked for healthy adults: 6MWD_male = (324.6×height_m) – (0.322×age_yrs) – (1.65×weight_kg) + 99.8.

6MWD_female = (779×height_m) + (0.136× age_yrs) – (1.88×weight_kg) – 632.4

Conclusion: Six-minute walk test is a safe and simple instrument for demonstrating cardiovascular responses to sub-maximal exercise and that 6-MWD in healthy Nigerian cannot be predicted by established reference equations from other populations. These reference equations may be usedto compute the percent predicted 6-MWD for individual adult patientsperforming the test for the first time, when using the standardizedprotocol in this population.