Cardio-respiratory responses to moderately heavy aerobic exercise during the Ramadan fasts

Objective: The aim of this study was to quantify the magnitude of the cardi ovascular and respiratory changes that occur during the month of Ramadan in response to moderately heavy aerobic physical exertion. Methods: Eighteen sedentary Kuwaiti adult males were tested under thermo-ne utral conditions during a spring-like month of Ramadan and one month therea fter. Results: There were no significant changes in maximal exercise capacity, tr eadmill walking efficiency, percentage VO2 max, in body weight and composit ion associated with Ramadan fasting or one month after. Cardiac (heart rate ) and ventilatory responses to moderately intense bouts of sub-maximal aero bic exercise (70% of VO2 max) were actually slightly (<5%) but significantl y (P<0.05) reduced, while exercise systolic but not diastolic pressure incr eased slightly (6%) by the end of Ramadan. Conclusions: Hormonal changes associated with dehydration or fasting, abste ntion from consumption of substances with negative inotropy and changes in circadian rhythms during Ramadan may be responsible for these mild changes in cardiorespiratory responses to exercise. Such changes had no negative ef fect on the physical aerobic performance of these subjects while exercising at moderately heavy intensity under thermally neutral conditions, during t he month of Ramadan. Reduced ventilation during exercise may reflect a limi ted glycolytic capacity by the end of Ramadan.