Walking For Pleasure, Burning The Fat: Subjective Responses Approximate To Maximal Fat Oxidation Intensities.

Identifying appropriate exercise intensities is critical for fitness professionals working with certain populations. For individuals desiring weight loss, an intensity that elicits the point of maximal fat oxidation (FATox) may be appropriate. This intensity reflects the point of greatest fat utilization for energy cost and marks the beginning of a shift to carbohydrate utilization, but little is known about subjective responses approximate to this intensity. PURPOSE: To determine perceptual and affective responses across walking exercise intensities used to elicit FATox. METHODS: Eleven apparently healthy college-aged female participants (age: 20.91 ± 1.14 yrs; BMI: 22.83 ± 5.28 kg.m2; height: 164.06 ± 7.55 cm; weight: 63.69 ± 10.23 kg) performed the following treadmill walking exercise protocol: a 3-min warm-up at 58.96 m.min-1 followed by six 3-min stages at 88.44 m.min-1 with 3% gradient increases (0-15%) each stage. FATox was measured via indirect calorimetry and calculated using expired VO2 and VCO2 values. Subjective measures of ratings of perceived exertion (RPE) and affect (Feeling Scale; FS) were assessed during the last 15 secs of each stage. A repeated-measures ANOVA (Stage 1 [S1], point of FATox [S2], End of exercise [S3]) with Bonferroni pairwise comparisons was calculated on all dependent variables (M ± SD). RESULTS: FATox, RPE, and FS all evidenced a significant time effect (ps < .001). FATox showed significant time point comparisons between S1 (.53 ± .12 g.min-1) and S3 (.33 ± .23 g.min-1; p = .008) and S2 (.61 ± .11 g.min-1) and S3 (p < .001). RPE showed significant time point comparisons from S1 (9.09 ± 1.86) to S2 (12.36 ± 2.33; p = .005); from S2 to S3 (15.00 ± 1.79; p = .003) and S1 to S3 (p < .001). FS showed significant time point comparisons from both S1 (2.91 ± 1.51) to S2 (1.27 ± 1.35; p = .033) and S3 (-.18 ± 1.54; p < .011). CONCLUSIONS: Walking intensity past the point of FATox resulted in less fat and greater carbohydrate utilization which, in turn, appears to result in increasingly greater effort sense. This range of exercise intensity appears to also reduce feelings of pleasure significantly. Fitness professionals may want to tailor walking exercise intensities that elicit perceived exertion responses around 13 (Somewhat Hard) as these may correspond to feelings of pleasure (Fairly Good) and FATox.