Symmetry and Asymmetry in Bouncing Gaits

Cavagna, G

doi:10.3390/sym2031270

Cited by 37 publications

(37 citation statements)

References 92 publications

(161 reference statements)

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“…The mono‐exponential fitting used in P horizontal (the simple method proposed by Samozino et al) does not account for the velocity oscillation that occurs at each foot contact, where the foot touches the ground in front of BCoM causing a braking/decelerating action. This occurs because, differently from moving on wheels, humans expose their BCoM to deceleration/acceleration sequences at each foot contact in their rimless‐spoked‐wheel locomotion . During running, this causes a velocity oscillation along the mean (monotonically) increasing velocity of the subject that deviates from the mono‐exponential fitting (Figure C).…”

Section: Discussionmentioning

confidence: 99%

“…This occurs because, differently from moving on wheels, humans expose their BCoM to deceleration/acceleration sequences at each foot contact in their rimless-spoked-wheel locomotion. 46 During running, this causes a velocity oscillation along the mean (monotonically) increasing velocity of the subject that deviates from the mono-exponential fitting ( Figure 6C). The difference between P f and P horizontal can thus be considered to represent the power for accelerating BCoM forward at each stance; this power difference is greater at the beginning of a sprint and becomes negligible at the end of the acceleration phase ( Figure 6C).…”

Section: F I G U R Ementioning

confidence: 94%

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Comprehensive mechanical power analysis in sprint running acceleration

Pavei

Zamparo

Fujii

et al. 2019

Scandinavian Med Sci Sports

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Sprint running is a common feature of many sport activities. The ability of an athlete to cover a distance in the shortest time relies on his/her power production. The aim of this study was to provide an exhaustive description of the mechanical determinants of power output in sprint running acceleration and to check whether a predictive equation for internal power designed for steady locomotion is applicable to sprint running acceleration. Eighteen subjects performed two 20 m sprints in a gym. A 35‐camera motion capture system recorded the 3D motion of the body segments and the body center of mass (BCoM) trajectory was computed. The mechanical power to accelerate and rise BCoM (external power, Pext) and to accelerate the segments with respect to BCoM (internal power, Pint) was calculated. In a 20 m sprint, the power to accelerate the body forward accounts for 50% of total power; Pint accounts for 41% and the power to rise BCoM accounts for 9% of total power. All the components of total mechanical power increase linearly with mean sprint velocity. A published equation for Pint prediction in steady locomotion has been adapted (the compound factor q accounting for the limbs' inertia decreases as a function of the distance within the sprint, differently from steady locomotion) and is still able to predict experimental Pint in a 20 m sprint with a bias of 0.70 ± 0.93 W kg−1. This equation can be used to include Pint also in other methods that estimate external horizontal power only.

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Section: Discussionmentioning

confidence: 99%

Section: F I G U R Ementioning

confidence: 94%

Comprehensive mechanical power analysis in sprint running acceleration

Pavei

Zamparo

Fujii

et al. 2019

Scandinavian Med Sci Sports

View full text Add to dashboard Cite

show abstract

“…In addition, running biomechanics depend on the environment in which individuals run . For instance, an increase in running speed typically reduces t c and increases t a (Brughelli et al, 2011), while the braking ðt À c Þ and propulsion ðt þ c Þ times become more symmetrical ðt À c % t þ c Þ (Cavagna, 2006(Cavagna, , 2010 and align more closely with the spring-mass model as running speed increases. The storage and release of elastic energy could be enhanced at higher running speeds, with a short t c and high t a becoming more efficient (Cavagna et al, 2008a).…”

Section: Introductionmentioning

confidence: 91%

“…where i=c or a. The ratios Dz þ c /Δz c and t þ c /t c as well as Dz þ a /z a and t þ a /t a were also calculated to explore upward and downward movement symmetries (Cavagna, 2010).…”

Section: Biomechanical Parametersmentioning

confidence: 99%

The implications of time on the ground on running economy: less is not always better

Lussiana

Patoz²,

Gindre³

et al. 2019

Journal of Experimental Biology

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A lower duty factor (DF) reflects a greater relative contribution of leg swing versus ground contact time during the running step. Increasing time on the ground has been reported in the scientific literature to both increase and decrease the energy cost (EC) of running, with DF reported to be highly variable in runners. As increasing running speed aligns running kinematics more closely with spring-mass model behaviours and re-use of elastic energy, we compared the centre of mass (COM) displacement and EC between runners with a low (DF low ) and high (DF high ) duty factor at typical endurance running speeds. Forty well-trained runners were divided in two groups based on their mean DF measured across a range of speeds. EC was measured from 4 min treadmill runs at 10, 12 and 14 km h −1 using indirect calorimetry. Temporal characteristics and COM displacement data of the running step were recorded from 30 s treadmill runs at 10, 12, 14, 16 and 18 km h −1 . Across speeds, DF low exhibited more symmetrical patterns between braking and propulsion phases in terms of time and vertical COM displacement than DF high . DF high limited global vertical COM displacements in favour of horizontal progression during ground contact. Despite these running kinematics differences, no significant difference in EC was observed between groups. Therefore, both DF strategies seem energetically efficient at endurance running speeds.

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“…Factors that determine the more economic choice of step frequency in forward running are: (i) tuning the step frequency to the natural frequency of the bouncing system, and (ii) choosing a step frequency that minimizes the total aerobic-limited step average power within the limits set by the anaerobic-limited push average power (Cavagna, 2010). The first strategy is usually adopted at low running speeds and abandoned for the second strategy at high running speeds by increasing the average upward acceleration above 1g during the lower part of the vertical oscillation of the centre of mass.…”

Section: Introductionmentioning

confidence: 99%

An analysis of the rebound of the body in backward human running

Cavagna

Legramandi

Torre

2012

Journal of Experimental Biology

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SUMMARYStep frequency and energy expenditure are greater in backward running than in forward running. The differences in the motion of the centre of mass of the body associated with these findings are not known. These differences were measured here on nine trained subjects during backward and forward running steps on a force platform at 3-17kmh -1. In contrast to previous reports, we found that the maximal upward acceleration of the centre of mass and the aerial phase, averaged over the whole speed range, are greater in backward running than in forward running (15.7 versus 13.2ms -2 , P1.9ϫ10 -6 and 0.098 versus 0.072s, P2.4ϫ10, respectively). Opposite to forward running, the impulse on the ground is directed more vertically during the push at the end of stance than during the brake at the beginning of stance. The higher step frequency in backward running is explained by a greater mass-specific vertical stiffness of the bouncing system (499 versus 352s -2 , P2.3ϫ10) resulting in a shorter duration of the lower part of the vertical oscillation of the centre of mass when the force is greater than body weight, with a similar duration of the upper part when the force is lower than body weight. As in a catapult, muscle-tendon units are stretched more slowly during the brake at the beginning of stance and shorten more rapidly during the push at the end of stance. We suggest that the catapultlike mechanism of backward running, although requiring greater energy expenditure and not providing a smoother ride, may allow a safer stretch-shorten cycle of muscle-tendon units.

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Symmetry and Asymmetry in Bouncing Gaits

Cited by 37 publications

References 92 publications

Comprehensive mechanical power analysis in sprint running acceleration

Comprehensive mechanical power analysis in sprint running acceleration

The implications of time on the ground on running economy: less is not always better

An analysis of the rebound of the body in backward human running

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