Physiological Adaptation to High-Altitude Conditions Among Pilgrims Returning from the Hajj in Katsina State

Hajj pilgrimage involves prolonged physical exertion, heat stress, and altitude exposure, creating a uniquely complex physiological environment for millions of Nigerian Muslims annually. This study examined physiological adaptations among Hajj pilgrims returning to Katsina State, North West Nigeria. Sixty returning pilgrims were assessed within 48 hours and again at two weeks post-return. Measured parameters included blood pressure, resting heart rate, haemoglobin concentration, oxygen saturation, and body weight. A control group of 30 non-pilgrims from the same community was recruited for comparison at baseline. Descriptive and inferential statistics including paired t-tests and repeated-measures ANOVA were applied. Results showed elevated haemoglobin concentration upon return, consistent with polycythaemic adaptation to altitude and dehydration. Oxygen saturation had normalised to control levels by the two-week follow-up. Resting heart rate was significantly elevated on initial return but returned to baseline over two weeks. Body weight was significantly reduced post-pilgrimage, reflecting energy expenditure and fluid loss. Blood pressure showed a non-significant downward trend in returning pilgrims. The study concludes that Hajj pilgrimage induces temporary but measurable haematological and cardiovascular physiological changes that resolve within weeks. Medical screening prior to and following pilgrimage is recommended, particularly for elderly participants from Katsina State. Keywords: Hajj pilgrimage, altitude adaptation, haemoglobin, oxygen saturation, Katsina.