Acute effects of submaximal exercise on respiratory rate and work output among physically inactive young adults

Abstract

Purpose: This experimental study aimed to determine the effects of exercise at submaximal intensity on respiratory rate (RR) and work output (WO) in physically inactive young adults. Method: A total of 90 participants (Mean age = 20.89 ± 1.68 years) was assigned into three groups (15 males and 15 females in each group) according to their body mass index (BMI = kg/m2) (Normal weight, NW = 18.5-24.9, Overweight, OW = 25.0-29.9, Obese, OB = ≥ 30.0, n = 30 each). Participants were instructed to walk or run on a treadmill, with a fixed inclination (8%) but the speed was progressed according to the modified Bruce Treadmill Protocol to reach a submaximal intensity which was determined based on the Karvonen Formula (65-85% maximal heart rate) for 20-min. RR was measured at baseline, and after completing the exercise at 0-, 5-, 10-, 20-, and 30-min. WO was measured immediately after the exercise (0-min). Results: There was a significant difference in RR among the groups (p < 0.05) with NW showed the lowest while OB showed the highest at all measured times. WO was significantly different among the groups (p < 0.05), with OB showed the highest and NW the lowest. Conclusion: Participants with excess body weight may increase their work of breathing and expend more WO due to a higher metabolic demand. Hence, it is suggested that exercise recommendation for physically inactive individuals with excess body weight should be individualized according to their BMI. The exercise prescription should include a longer duration of warming-up and cooling-down and followed by conditioning exercises at a lower intensity. Such strategy may delay fatigue and promote adherence to exercise.