Frictional internal work of damped limbs oscillation in human locomotion

Minetti, Alberto E.; Moorhead, Alex P.; Pavei, Gaspare

doi:10.1098/rspb.2020.1410

Cited by 13 publications

(11 citation statements)

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“…Interestingly, similar modifications of the control of locomotion were observed when the imbalance between positive and negative work was generated by a horizontal traction force (Dewolf et al, 2020). These results suggest that, though factors other than work also clearly influence the preferred movement strategy, the choice of gait pattern largely depends on the mechanical work that must be Minetti et al, 2020). Finally, CoT is calculated from the ratio of net oxygen consumption (above resting values) and horizontal velocity (red box).…”

Section: New Findingsmentioning

confidence: 72%

“…The effects of such a bias, in real locomotion, will depend on gait type and on the fractional mass of limbs with respect to the whole body, but the exact amount still needs to be substantiated. The new measurements of frictional W INT (Minetti et al, 2020), by completing the work balance of locomotion, should help shed light on the interplay between W INT and W EXT in different gait paradigms (Figure 1). Finally, there is still no gold standard in the literature that deterministically considers all parts of mechanical work (and their 'interdependence').…”

Section: Methodological Considerationsmentioning

confidence: 99%

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Mechanical work as a (key) determinant of energy cost in human locomotion: recent findings and future directions

Peyré‐Tartaruga

Dewolf

Prampero

et al. 2021

Experimental Physiology

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During locomotion, muscles use metabolic energy to produce mechanical work (in a more or less efficient way), and energetics and mechanics can be considered as two sides of the same coin, the latter being investigated to understand the former. A mechanical approach based on König's theorem (Fenn's approach) has proved to be a useful tool to elucidate the determinants of the energy cost of locomotion (e.g., the pendulum-like model of walking and the bouncing model of running) and has resulted in many advances in this field. During the past 60 years, this approach has been refined and applied to explore the determinants of energy cost and efficiency in a variety of conditions (e.g., low gravity, unsteady speed). This narrative review aims to summarize current knowledge of the role that mechanical work has played in our understanding of energy cost to date, and to underline how recent developments in analytical methods and their applications in specific locomotion modalities (on a gradient, at low gravity and in unsteady conditions) and in pathological gaits (asymmetric gait pathologies, obese subjects and in the elderly) could continue to push this understanding further. The recent in vivo quantification of new aspects that should be included in the assessment of mechanical work (e.g., frictional internal work and elastic contribution) deserves future research that would improve our knowledge of the

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Section: New Findingsmentioning

confidence: 72%

Section: Methodological Considerationsmentioning

confidence: 99%

Mechanical work as a (key) determinant of energy cost in human locomotion: recent findings and future directions

Peyré‐Tartaruga

Dewolf

Prampero

et al. 2021

Experimental Physiology

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“…This is not the case in the present study, as we define the optimal speed as that of the minimum mechanical energy expenditure, W ext . Several studies showed that other mechanical work must contribute to the metabolic energy output: (1) the internal work as a result of the kinetic energy changes of the limbs relative to the center of mass (Cavagna and Kaneko, 1977), (2) the work to redirect the center of mass velocity from one inverted pendulum to the other (Donelan et al, 2001(Donelan et al, , 2002a, (3) the internal work done by one leg against the other during double contact (Bastien et al, 2003) and (4) the internal work done against frictional losses (Minetti et al, 2020). Furthermore, the optimal speed determined by the minimum W ext differs between subjects (Fig.…”

Section: Discussionmentioning

confidence: 99%

The phase shift between potential and kinetic energy in human walking

Cavagna

Legramandi

2020

Journal of Experimental Biology

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It is known that mechanical work to sustain walking is reduced thanks to a transfer of gravitational potential energy into kinetic energy as in a pendulum. The factors affecting this transfer are unclear. In particular it is not known the phase relationship between potential and kinetic energy curves of the center of mass. This relationship has been measured in this study. The normalized time intervals: i) α, between maximum of kinetic energy in the sagittal plane Ek and minimum of gravitational potential energy Ep, and ii) β, between minimum of Ek and maximum of Ep, have been measured during walking at various speeds (0.5-2.5 m s−1). In our group of subjects, α=β at 1.6 m s−1, indicating that, at this speed, the time difference between Ep-Ek extremes is the same at the top and the bottom of the trajectory of the center of mass. It turns out that at the same speed: i) the work done to lift the center of mass equals the work to accelerate it forwards, ii) the Ep-Ek energy transfer approaches a maximum and iii) the mass specific external work per unit distance approaches a minimum.

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“…This is because walking with shortened steps causes an elevated cost of swinging the legs due to the increased cadence (Doke et al ., 2005; Minetti et al ., 1995). Leg swing at a high cadence is particularly costly as it requires a large amount of internal work performed by muscles to rapidly accelerate the limbs with respect to the COM while overcoming limb friction (Cavagna and Kaneko, 1977; Minetti et al ., 2020). Walking with lengthened steps causes an elevated cost associated with redirecting the body's COM (Adamczyk and Kuo, 2009; Cavagna and Franzetti, 1986; Donelan et al ., 2002; Kuo et al ., 2005).…”

Section: Discussionmentioning

confidence: 99%

The human preference for symmetric walking often disappears when one leg is constrained

Browne

Smock

Roemmich

2020

The Journal of Physiology

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Key points We hypothesized that minimization of metabolic power could drive people to walk asymmetrically when one leg is constrained We studied healthy young adults and independently constrained one or both step lengths to be markedly shorter or longer than preferred using visual feedback When one leg was constrained to take a shorter or longer step than preferred, asymmetric walking patterns were less metabolically costly than symmetric walking patterns When one leg was constrained to take a shorter or longer step than preferred and the other leg was allowed to move freely, most participants naturally adopted an asymmetric gait People may prefer to walk asymmetrically to minimize metabolic power when the function of one leg is constrained during fixed‐speed treadmill walking Abstract The bilateral symmetry inherent in healthy human walking is often disrupted in clinical conditions that primarily affect one leg (e.g. stroke). This seems intuitive: with one leg constrained, gait becomes asymmetric. However, the emergence of asymmetry is not inevitable. Consider that symmetric walking could be preserved by matching the movement of the unconstrained leg to that of the constrained leg. While this is theoretically possible, it is rarely observed in clinical populations. Here, we hypothesized that minimization of metabolic power could drive people to walk asymmetrically when one leg is constrained, even when symmetric walking remains possible. We tested this hypothesis by performing two experiments in healthy adults. In Experiment 1, we constrained one step to be markedly shorter or longer than preferred. We observed that participants could significantly reduce metabolic power by adopting an asymmetric gait (one short/long step, one preferred step) rather than maintaining a symmetric gait (bilateral short/long steps). Indeed, when allowed to walk freely in this situation, participants naturally adopted a less effortful asymmetric gait. In Experiment 2, we applied a milder constraint that more closely approximated magnitudes of step length asymmetry that are observed in clinical populations. Responses in this experiment were more heterogeneous, though most participants adopted an asymmetric gait. These findings support two central conclusions: (1) symmetry is not necessarily energetically optimal in constrained human walking, and (2) people may prefer to walk asymmetrically to minimize metabolic power when one leg is constrained during fixed‐speed treadmill walking, especially when the constraint is large.

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Frictional internal work of damped limbs oscillation in human locomotion

Cited by 13 publications

References 35 publications

Mechanical work as a (key) determinant of energy cost in human locomotion: recent findings and future directions

Mechanical work as a (key) determinant of energy cost in human locomotion: recent findings and future directions

The phase shift between potential and kinetic energy in human walking

The human preference for symmetric walking often disappears when one leg is constrained

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