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Université de Fribourg

Permutation invariant properties of primitive cubic quadruples

Hürlimann, Werner

In: The Ramanujan Journal, 2017, vol. 43, no. 3, p. 649–662

Based on a specific quadratic Hopf map between the Euclidean spaces of dimension four and three that is associated with Euler’s complete rational parameterization of the four cubes equation, we study the permutation invariant properties of the primitive integer cubic quadruples that solve this equation. Fixing the coordinate with maximum height and taking it positive, our main result...

Université de Fribourg

Standing economy: does the heterogeneity in the energy cost of posture maintenance reside in differential patterns of spontaneous weight-shifting?

Miles-Chan, Jennifer L. ; Fares, Elie-Jacques ; Berkachy, Redina ; Jacquet, Philippe ; Isacco, Laurie ; Schutz, Yves ; Montani, Jean-Pierre ; Dulloo, Abdul G.

In: European Journal of Applied Physiology, 2017, vol. 117, no. 4, p. 795–807

Due to sedentarity-associated disease risks, there is much interest in methods to increase low-intensity physical activity. In this context, it is widely assumed that altering posture allocation can modify energy expenditure (EE) to impact body-weight regulation and health. However, we have recently shown the existence of two distinct phenotypes pertaining to the energy cost of...

Université de Fribourg

Energy cost of standing in a multi-ethnic cohort: are energy-savers a minority or the majority?

Monnard, Cathríona R. ; Miles-Chan, Jennifer L.

In: PLOS ONE, 2017, vol. 12, no. 1, p. e0169478

The disease risks associated with sedentary behavior are now firmly established, and consequently there is much interest in methods of increasing low-intensity physical activity. In this context, it is a widely held belief that altering posture allocation can modify energy expenditure (EE) to impact upon body weight regulation and health. However, we recently showed the existence of two...

Université de Fribourg

Isometric thermogenesis at rest and during movement: a neglected variable in energy expenditure and obesity predisposition

Dulloo, Abdul G. ; Miles-Chan, Jennifer L. ; Montani, Jean-Pierre ; Schutz, Yves

In: Obesity Reviews, 2017, vol. 18, no. S1, p. 56–64

Isometric thermogenesis as applied to human energy expenditure refers to heat production resulting from increased muscle tension. While most physical activities consist of both dynamic and static (isometric) muscle actions, the isometric component is very often essential for the optimal performance of dynamic work given its role in coordinating posture during standing, walking and most...

Université de Fribourg

Age-related differences in corticospinal excitability during observation and motor imagery of balance tasks

Mouthon, Audrey A. ; Ruffieux, Jan ; Keller, Martin ; Taube, Wolfgang

In: Frontiers in Aging Neuroscience, 2016, vol. 8, p. -

Postural control declines across adult lifespan. Non-physical balance training has been suggested as an alternative to improve postural control in frail/immobilized elderly people. Previous studies showed that this kind of training can improve balance control in young and older adults. However, it is unclear whether the brain of young and older adults is activated differently during mental...

Université de Fribourg

Antarctica on foot: the energy expended to walk, ski and man-haul

Halsey, L. G. ; Lambert, R. ; Collins, P. ; Newnham, A. ; Kumar, Alexander ; O’Driscoll, C. ; Stroud, M. A.

In: Polar Biology, 2016, vol. 39, no. 4, p. 627-637

Polar exploration often involves travelling on foot and thus is physically intensive, with long-term excursions typically resulting in weight loss. Few studies have investigated the energy expended under such circumstances. Here, we present a range of prediction equations for estimating metabolic rate from heart rate or accelerometry data for specific activities including skiing and man-hauling...

Université de Fribourg

Postural challenge affects motor cortical activity in young and old adults

Papegaaij, Selma ; Taube, Wolfgang ; Keeken, Helco G. van ; Otten, Egbert ; Baudry, Stéphane ; Hortobágyi, Tibor

In: Experimental Gerontology, 2016, vol. 73, p. 78–85

When humans voluntarily activate a muscle, intracortical inhibition decreases. Such a decrease also occurs in the presence of a postural challenge and more so with increasing age. Here, we examined age-related changes in motor cortical activity during postural and non-postural contractions with varying levels of postural challenge. Fourteen young (age 22) and twelve old adults (age 70) performed...