Fat Oxidation Differences in Deconditioned Normal Weight and Obese Individuals on a Lower Body Positive Pressure Treadmill

Purpose: To determine the differences in peak fat oxidation (PFO), peak oxygen consumption (VO 2peak ) and respiratory exchange ratio (RER) while walking at 100% and 75% on a lower body positive pressure treadmill (LBPP) in normal weight compared to obese men.Methods: Fourteen normal weight men (mean age 23.2 ± 2.4 years, BMI 27.5 ± 3.8 kg/m 2 and body fat % 14.22 ± 7.0%) and fourteen obese men (mean age 23.2 ± 2.4 years, BMI 36.5 ± 3.8 kg/m 2 and body fat % 38.6 ± 7.0%) were randomly assigned to walking on the LBPP treadmill at 100% and 75% of their body weight.Body composition was assessed by hydrostatic weighing.The protocol consisted of 3-minute stages at a constant speed of 3.3 mph where percent grade increased three minutes following the warm up from 3% to a maximum of 15%.PFO, RER and VO 2peak were measured using indirect calorimetry.Fat oxidation rates were calculated using stoichiometric equations.Results: There were no significant differences in VO 2peak , however according to Wilks's statistic, there was a significant effect on fat oxidation in the normal weight group compared to the overweight group, λ = .70,F(2,25) = 5.36, p < .05 in the 100% BW condition.There was also a significant effect on RER in the normal weight group compared to the overweight group, using Wilks's statistic, λ = .74,F(2,25) = 4.54, p < 0 .05 in the 100% condition.Conclusion: The study suggests that100% of one's body weight increased carbohydrate use in the OW/OB population and can be due to the fact that their weight causes them to work anaerobically compared to the normal weight population.Therefore, the OW/OB population should work at a lower intensity to increase fat oxidation so they can become more fit, and the untrained NW subjects could exercise at higher intensities with similar results.