Weight loss does not affect the sit-to-stand metabolic cost in adolescents with obesity

The Energetic Saver Profile From Sit-to-Stand Does Not Persist During Very Low-Intensity Physical Activity in Healthy Men and Women

BACKGROUND

It is essential to better characterize the energetic profile of individuals during very low-intensity physical activity. The objectives of the present study were to determine whether the saver profile from sit-to-stand persists during light physical activity and characterize patterns in substrate utilization from sit-to-stand and during very low-intensity physical activity in healthy men and women.

METHODS

Sixty-two healthy adults (38 women) performed an experimental sequence that corresponded to 15-minute sitting (SIT1), followed by 15-minute standing (STAND), 15-minute sitting again (SIT2), and finally 15 minutes of light cycling. Continuous indirect calorimetry was allowed to calculate energy expenditure (EE) and respiratory quotient through the entire sequence. Savers and nonsavers (<5% and ≥ 5% increase in EE from sitting to standing, respectively) were determined.

RESULTS

There was an interaction effect in EE between savers and nonsavers through the whole sequence (P = .008). Only nonsavers (71%) exhibited a significant increase in EE from SIT1 to STAND (P < .001). Nonsavers and savers significantly increased EE during 15 minutes of light cycling relative to sitting or standing (P < .001), without any difference between groups. The percentage of change in respiratory quotient from SIT1 to STAND was significantly different between the 2 groups, with increased values in savers and decreased values in nonsavers (P = .03). Significantly lower values in respiratory quotient and EE were found during 15 minutes of light cycling in women compared with men (P < .001).

CONCLUSIONS

It is essential to determine individuals' energetic phenotype to determine those who may benefit more from strategies such as standing or light physical activity. The sexual dimorphism in terms of substrate use during such exercise should be considered.

Improved walking energy efficiency might persist in presence of simulated full weight regain after multidisciplinary weight loss in adolescents with obesity: the POWELL study

AIM

Weight loss leads to a reduction of the energy cost of walking but the respective implications of the metabolic and mechanic changes remain unknown. The present study compares the post-weight loss energy cost of walking (Cw) with and without a total reload of the induced weight reduction in adolescents with obesity.

METHODS

Energy cost of walking and substrate use were evaluated during a graded walking exercise (4×6-min at 0.75, 1, 1.25, 1.5 m.s-1) before (V1) and after a 12-week intervention in 21 adolescents with obesity (11 girls; 13.8 ± 1.4 y). After weight loss, the walking exercise was randomly repeated once without weight reload (V2) and once with a loading corresponding to the total induced weight loss during the program (V2L). Body composition was assessed before and after the intervention.

RESULTS

Body weight and fat mass decreased in response to the 12-week intervention (p < 0.001), while FFM did not change. The absolute gross Cw (ml.m-1) was higher on V1 compared with V2 at every speed. The absolute net Cw (ml.m-1) was higher on V1 compared to V2L at 0.75 m.s-1 (p = 0.04) and 1 m.s-1 (p = 0.02) and higher on V2L compared with V2 at 1.5 m.s-1 (p = 0.03). Net Cw (ml.m-1.kg-1) on V1 being higher than V2 (p < 0.001), and V2L higher than V2 (p = 0.006). The absolute CHO oxidation (mg.min-1) did not show any condition effect (p = 0.12) while fat utilization was higher on V1 compared to V2 and V2L (p < 0.001). Relative to body weight CHO oxidation was lower on V1 compared to V2 (p = 0.04) and V2L (p = 0.004) while relative to body weight fat oxidation was higher on V1 than V2 (p = 0.002).

CONCLUSION

Adolescents with obesity might not show an entire rise back to pre-weight loss values of their metabolic cost of walking when weight gain is simulated. These new findings suggest metabolic and physiological adaptations to weight loss of the energy metabolism that remain to be clarified.

Do Sit-Stand Tables Affect Physical Behavior and Body Composition Similarly in Normal-Weight and Overweight Office Workers? A Pilot Study

OCCUPATIONAL APPLICATIONSSedentary behavior is a significant health concern among office workers. We completed the same 6-month sit-stand table intervention at work for groups of normal-weight and overweight workers, and compared it to not having sit-stand tables. The intervention caused the intended decrease in sitting time in both groups and a corresponding increase in standing. We did not find compensation effects on physical behavior outside of work. Furthermore, the intervention did not change the composition of fat, lean, and bone mass in either group. Thus, strategies including initiatives to increase physical activity are likely needed to have effects on body composition; and an intervention needs to be sustained for longer than six months for any changes in body composition to be observed.