We are finalizing a study with the validation of the mechanical and energetic behavior of our muscle-tendon model during work-loops. The outcome will hopefully allow us to use a model to adequately predict oxygen consumption or metabolic cost of muscle contractions. Such a model has two major major advantages. First, having a validated model of a muscle-tendon unit reduces the necessity of performing invasive animal studies. Second, a model allows us to estimate the mechanic and energetic variables that are not accessible during human experiments.
To be able to adequately predict behavior of human muscles, we need to extrapolate the mice experimental data and the mouse muscle-tendon model and is done in a second line of research. This study is a crucial step in linking mouse oxygen consumption experiments to a full body optimal control model of human walking capable of predicting the metabolic cost of walking.
One of our goals that should be able to make a substantial societal impact is to investigate the energetics of walking in elderly. Even though many studies report that elderly walk with an increased energetic cost, it is very difficult to compare results across different studies due to differences in methodologies and due to differences in analyses. We have ran an extensive meta-analysis on the topic of the relationship between age and metabolic cost of walking. The main conclusion of the paper was that there is indeed a substantial and significant increase in the energetic cost of walking the elderly. However, we found a possible confounding factor and that was the use of a treadmill. In particular, we found evidence that suggests that the energetic cost of walking on a treadmill is increased in elderly, but not in young adults with respect to normal over-ground walking.
This led us to perform a large experimental study that, in line with our expectations, showed that the elevation in metabolic cost of walking in elderly is due to walking on a treadmill, which is different for older adults than for younger adults. We first showed that there is no statistical elevation in elderly compared to young adults when walking over-ground. Second, during the first encounter with walking on a treadmill, elderly walk with substantial higher metabolic cost that their healthy peers. However, this elevations is completely gone after ample training on the treadmill.
Interestingly, the writing of this article was delayed because we encountered a flaw in a standard method that is very often used for movement analysis (“inverse dynamics analysis”). We have found a solution to that problem and have written an article on how to adjust this.
We have published a long commentary on a new theory of walking that was published in an esteemed journal. The original paper suggested that people could use gravity to propel ourselves forward and could even walk uphill for free when adopting a particular walking technique; this goes against the law of thermodynamics. Because it attracted so much attention in the media, we felt compelled to write a detailed commentary on their paper in which we clearly explained why the mechanics and energetics of this paper is flawed.
