Brief observation
Unstable Shoes Increase Energy Expenditure of Obese Patients

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Abstract

Background

Ergonomic unstable shoes, which are widely available to the general population, could increase daily non-exercise activity thermogenesis as the result of increased muscular involvement. We compared the energy expenditure of obese patients during standing and walking with conventional flat-bottomed shoes versus unstable shoes.

Methods

Twenty-nine obese patients were asked to stand quietly and to walk at their preferred walking speed while wearing unstable or conventional shoes. The main outcome measures were metabolic rate of standing and gross and net energy cost of walking, as assessed with indirect calorimetry.

Results

Metabolic rate of standing was higher while wearing unstable shoes compared with conventional shoes (1.11 ± 0.20 W/kg−1vs 1.06 ± 0.23 W/kg−1, P = .0098). Gross and net energy cost of walking were higher while wearing unstable shoes compared with conventional shoes (gross: 4.20 ± 0.42 J/kg−1/m−1vs 4.01 ± 0.39 J/kg−1/m−1, P = .0035; net: 3.37 ± 0.41 J/kg−1/m−1vs 3.21 ± 0.37 J/kg−1/m−1; P = .032).

Conclusion

In obese patients, it is possible to increase energy expenditure of standing and walking by means of ergonomic unstable footwear. Long-term use of unstable shoes may eventually prevent a positive energy balance.

Section snippets

Subjects

Twenty-nine adult obese men (n = 10) and women (n = 19) volunteered to participate in the study (Table 1). Inclusion criteria were age ≥ 18 years; body mass index ≥ 30 kg/m−2; and absence of severe and uncontrolled hypertension, overt uncompensated diabetes, and any neurologic, orthopedic, or psychiatric disorder. The experimental procedures were approved by the ethical committee of the Italian Institute of Auxology, and all subjects gave written informed consent before participation.

Experimental Protocol

During the week

Results

The participants used the unstable shoes for a mean (standard deviation) of 25 (17) hours and 6.9 (3.9) days; these shoes were well tolerated, and no adverse effects were noted. Unstable shoes were significantly heavier than conventional shoes (+46%; P < .001); shoe sizes and gait parameters did not differ between the 2 experimental conditions (Table 2).

During quiet standing (Table 3), relative oxygen uptake and metabolic rate were significantly higher with unstable shoes compared with

Discussion

The main finding of this self-controlled study was that energy expenditure of obese patients during comfortable walking and standing was significantly increased by 5% to 7% as a result of wearing unstable shoes compared with conventional shoes.

The increased energy expenditure of quiet standing in unstable shoes could be attributed to greater anteroposterior and mediolateral postural sway,4, 5 which in turn may have enhanced the electromyographic activity of thigh, shank, and extrinsic foot

Conclusions

We strongly concur with the suggestion that efforts to enhance non-exercise activity thermogenesis activation, perhaps through behavioral cues, may be a fruitful approach for the prevention of obesity.1 The present findings suggest that if obese patients, such as those tested in our study, were to wear unstable shoes during their daily standing and walking time,3 then their non-exercise activity thermogenesis would increase on average by approximately 40 kcal/day−1, with all other things being

Acknowledgments

The authors thank Carlo Busti, Raffaela Galli, Alessandra De Col, and Alessandra Patrizi of the Italian Institute of Auxology for invaluable help during the experiments.

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Funding: Partial financial support (consumables) and unstable shoes were provided by Masai Marketing & Trading AG (Winterthur, Switzerland), but the company had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Conflict of Interest: None.

Authorship: All authors had access to the data and played a role in writing this manuscript.

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