Application of Leg, Vertical, and Joint Stiffness in Running Performance: A Literature Overview

Stiffness, the resistance to deformation due to force, has been used to model the way in which the lower body responds to landing during cyclic motions such as running and jumping. Vertical, leg, and joint stiffness provide a useful model for investigating the store and release of potential elastic energy via the musculotendinous unit in the stretch-shortening cycle and may provide insight into sport performance. This review is aimed at assessing the effect of vertical, leg, and joint stiffness on running performance as such an investigation may provide greater insight into performance during this common form of locomotion. PubMed and SPORTDiscus databases were searched resulting in 92 publications on vertical, leg, and joint stiffness and running performance. Vertical stiffness increases with running velocity and stride frequency. Higher vertical stiffness differentiated elite runners from lower-performing athletes and was also associated with a lower oxygen cost. In contrast, leg stiffness remains relatively constant with increasing velocity and is not strongly related to the aerobic demand and fatigue. Hip and knee joint stiffness are reported to increase with velocity, and a lower ankle and higher knee joint stiffness are linked to a lower oxygen cost of running; however, no relationship with performance has yet been investigated. Theoretically, there is a desired “leg-spring” stiffness value at which potential elastic energy return is maximised and this is specific to the individual. It appears that higher “leg-spring” stiffness is desirable for running performance; however, more research is needed to investigate the relationship of all three lower limb joint springs as the hip joint is often neglected. There is still no clear answer how training could affect mechanical stiffness during running. Studies including muscle activation and separate analyses of local tissues (tendons) are needed to investigate mechanical stiffness as a global variable associated with sports performance.

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Leg and Joint Stiffness Adaptations to Minimalist and Maximalist Running Shoes

Journal of Applied Biomechanics ◽

10.1123/jab.2020-0284 ◽

2021 ◽

pp. 1-7

Author(s):

Allison H. Gruber ◽

Shuqi Zhang ◽

Jiahao Pan ◽

Li Li

Keyword(s):

Knee Joint ◽

Impact Loading ◽

Repeated Measures ◽

Impact Force ◽

Reaction Force ◽

Joint Stiffness ◽

Initial Contact ◽

Vertical Stiffness ◽

Vertical Loading ◽

Force Characteristics

The running footwear literature reports a conceptual disconnect between shoe cushioning and external impact loading: footwear or surfaces with greater cushioning tend to result in greater impact force characteristics during running. Increased impact loading with maximalist footwear may reflect an altered lower-extremity gait strategy to adjust for running in compliant footwear. The authors hypothesized that ankle and knee joint stiffness would change to maintain the effective vertical stiffness, as cushioning changed with minimalist, traditional, and maximalist footwear. Eleven participants ran on an instrumental treadmill (3.5 m·s−1) for a 5-minute familiarization in each footwear, plus an additional 110 seconds before data collection. Vertical, leg, ankle, and knee joint stiffness and vertical impact force characteristics were calculated. Mixed model with repeated measures tested differences between footwear conditions. Compared with traditional and maximalist, the minimalist shoes were associated with greater average instantaneous and average vertical loading rates (P < .050), greater vertical stiffness (P ≤ .010), and less change in leg length between initial contact and peak resultant ground reaction force (P < .050). No other differences in stiffness or impact variables were observed. The shoe cushioning paradox did not hold in this study due to a similar musculoskeletal strategy for running in traditional and maximalist footwear and running with a more rigid limb in minimalist footwear.

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Hopping with degressive spring stiffness in a full-leg exoskeleton lowers metabolic cost compared with progressive spring stiffness and hopping without assistance

Journal of Applied Physiology ◽

10.1152/japplphysiol.01003.2018 ◽

2019 ◽

Vol 127 (2) ◽

pp. 520-530

Author(s):

Stephen P. Allen ◽

Alena M. Grabowski

Keyword(s):

Elastic Energy ◽

Metabolic Cost ◽

Spring Stiffness ◽

Metabolic Power ◽

Metabolic Demand ◽

Nonlinear Spring ◽

Vertical Stiffness ◽

Leg Stiffness ◽

Linear Spring ◽

Stiffness Profile

When humans hop with a passive-elastic exoskeleton with springs in parallel with both legs, net metabolic power (Pmet) decreases compared with normal hopping (NH). Furthermore, humans retain near-constant total vertical stiffness ( ktot) when hopping with such an exoskeleton. To determine how spring stiffness profile affects Pmet and biomechanics, 10 subjects hopped on both legs normally and with three full-leg exoskeletons that each used a different spring stiffness profile at 2.4, 2.6, 2.8, and 3.0 Hz. Each subject hopped with an exoskeleton that had a degressive spring stiffness (DGexo), where stiffness, the slope of force vs. displacement, is initially high but decreases with greater displacement, linear spring stiffness (LNexo), where stiffness is constant, or progressive spring stiffness (PGexo), where stiffness is initially low but increases with greater displacement. Compared with NH, use of the DGexo, LNexo, and PGexo numerically resulted in 13–24% lower, 4–12% lower, and 0–8% higher Pmet, respectively, at 2.4–3.0 Hz. Hopping with the DGexo reduced Pmet compared with NH at 2.4–2.6 Hz ( P ≤ 0.0457) and reduced Pmet compared with the PGexo at 2.4–2.8 Hz ( P < 0.001). ktot while hopping with each exoskeleton was not different compared with NH, suggesting that humans adjust leg stiffness to maintain overall stiffness regardless of the spring stiffness profile in an exoskeleton. Furthermore, the DGexo provided the greatest elastic energy return, followed by LNexo and PGexo ( P ≤ 0.001). Future full-leg, passive-elastic exoskeleton designs for hopping, and presumably running, should use a DGexo rather than an LNexo or a PGexo to minimize metabolic demand. NEW & NOTEWORTHY When humans hop at 2.4–3.0 Hz normally and with an exoskeleton with different spring stiffness profiles in parallel to the legs, net metabolic power is lowest when hopping with an exoskeleton with degressive spring stiffness. Total vertical stiffness is constant when using an exoskeleton with linear or nonlinear spring stiffness compared with normal hopping. In-parallel spring stiffness influences net metabolic power and biomechanics and should be considered when designing passive-elastic exoskeletons for hopping and running.

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Reducing the metabolic energy of walking and running using an unpowered hip exoskeleton

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-021-00893-5 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Tiancheng Zhou ◽

Caihua Xiong ◽

Juanjuan Zhang ◽

Di Hu ◽

Wenbin Chen ◽

...

Keyword(s):

Energy Consumption ◽

Design Method ◽

Metabolic Cost ◽

Metabolic Energy ◽

Spring Stiffness ◽

Spatiotemporal Parameters ◽

The Common ◽

Hip Flexion ◽

Optimal Stiffness ◽

Insight Into

Abstract Background Walking and running are the most common means of locomotion in human daily life. People have made advances in developing separate exoskeletons to reduce the metabolic rate of walking or running. However, the combined requirements of overcoming the fundamental biomechanical differences between the two gaits and minimizing the metabolic penalty of the exoskeleton mass make it challenging to develop an exoskeleton that can reduce the metabolic energy during both gaits. Here we show that the metabolic energy of both walking and running can be reduced by regulating the metabolic energy of hip flexion during the common energy consumption period of the two gaits using an unpowered hip exoskeleton. Methods We analyzed the metabolic rates, muscle activities and spatiotemporal parameters of 9 healthy subjects (mean ± s.t.d; 24.9 ± 3.7 years, 66.9 ± 8.7 kg, 1.76 ± 0.05 m) walking on a treadmill at a speed of 1.5 m s−1 and running at a speed of 2.5 m s−1 with different spring stiffnesses. After obtaining the optimal spring stiffness, we recruited the participants to walk and run with the assistance from a spring with optimal stiffness at different speeds to demonstrate the generality of the proposed approach. Results We found that the common optimal exoskeleton spring stiffness for walking and running was 83 Nm Rad−1, corresponding to 7.2% ± 1.2% (mean ± s.e.m, paired t-test p < 0.01) and 6.8% ± 1.0% (p < 0.01) metabolic reductions compared to walking and running without exoskeleton. The metabolic energy within the tested speed range can be reduced with the assistance except for low-speed walking (1.0 m s−1). Participants showed different changes in muscle activities with the assistance of the proposed exoskeleton. Conclusions This paper first demonstrates that the metabolic cost of walking and running can be reduced using an unpowered hip exoskeleton to regulate the metabolic energy of hip flexion. The design method based on analyzing the common energy consumption characteristics between gaits may inspire future exoskeletons that assist multiple gaits. The results of different changes in muscle activities provide new insight into human response to the same assistive principle for different gaits (walking and running).

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An insight into biomechanical study for replacement of knee joint

Materials Today Proceedings ◽

10.1016/j.matpr.2021.05.202 ◽

2021 ◽

Author(s):

M.A. Kumbhalkar ◽

K.S. Rambhad ◽

Nand Jee Kanu

Keyword(s):

Knee Joint ◽

Biomechanical Study ◽

Insight Into

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Knee Kinematics Estimation Using Multi-Body Optimisation Embedding a Knee Joint Stiffness Matrix: A Feasibility Study

PLoS ONE ◽

10.1371/journal.pone.0157010 ◽

2016 ◽

Vol 11 (6) ◽

pp. e0157010 ◽

Cited By ~ 13

Author(s):

Vincent Richard ◽

Giuliano Lamberto ◽

Tung-Wu Lu ◽

Aurelio Cappozzo ◽

Raphaël Dumas

Keyword(s):

Knee Joint ◽

Feasibility Study ◽

Stiffness Matrix ◽

Joint Stiffness ◽

Knee Kinematics ◽

Multi Body

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Knee joint stiffness during walking in knee osteoarthritis

Arthritis Care & Research ◽

10.1002/acr.20012 ◽

2010 ◽

Vol 62 (1) ◽

pp. 38-44 ◽

Cited By ~ 31

Author(s):

Sharon J. Dixon ◽

Rana S. Hinman ◽

Mark W. Creaby ◽

Georgie Kemp ◽

Kay M. Crossley

Keyword(s):

Knee Joint ◽

Knee Osteoarthritis ◽

Joint Stiffness

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A STUDY OF THE EFFECT OF COLD ON JOINT TEMPERATURE AND MOBILITY

Canadian Journal of Medical Sciences ◽

10.1139/cjms51-031 ◽

1951 ◽

Vol 29 (5) ◽

pp. 255-262 ◽

Cited By ~ 1

Author(s):

John Hunter ◽

M. G. Whillans

Keyword(s):

Knee Joint ◽

Test Object ◽

Joint Stiffness ◽

Ambient Temperatures ◽

Significant Fall ◽

Average Skin ◽

Skin Temperatures ◽

Rectal Muscle

Exposure to zero and subzero ambient temperatures results in a significant fall in joint temperature, where the knee joint of the cat was used as test object. The fall in rectal, muscle, and “average” skin temperatures for similar exposures is considerably less. Low joint temperature is associated with increased joint stiffness.

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Neuromuscular Reflexes Contribute to Knee Stiffness During Valgus Loading

Journal of Neurophysiology ◽

10.1152/jn.00921.2004 ◽

2005 ◽

Vol 93 (5) ◽

pp. 2698-2709 ◽

Cited By ~ 22

Author(s):

Y. Y. Dhaher ◽

A. D. Tsoumanis ◽

T. T. Houle ◽

W. Z. Rymer

Keyword(s):

Knee Joint ◽

Muscle Activation ◽

Joint Stiffness ◽

Muscle Contractions ◽

Emg Activity ◽

Lateral Direction ◽

Reflex Responses ◽

Torque Response ◽

Joint Dynamics ◽

Periarticular Tissue

We have previously shown that abduction angular perturbations applied to the knee consistently elicit reflex responses in knee joint musculature. Although a stabilizing role for such reflexes is widely proposed, there are as of yet no studies quantifying the contribution of these reflex responses to joint stiffness. In this study, we estimate the mechanical contributions of muscle contractions elicited by mechanical excitation of periarticular tissue receptors to medial-lateral knee joint stiffness. We hypothesize that these reflex muscle contractions will significantly increase knee joint stiffness in the adduction/abduction direction and enhance the overall stability of the knee. To assess medial-lateral joint stiffness, we applied an abducting positional deflection to the fully extended knee using a servomotor and recorded the torque response using a six degree-of-freedom load-cell. EMG activity was also recorded in both relaxed and preactivated quadriceps and hamstrings muscles with surface electrodes. A simple, linear, second-order, delayed model was used to describe the knee joint dynamics in the medial/lateral direction. Our data indicate that excitation of reflexes from periarticular tissue afferents results in a significant increase of the joint’s adduction-abduction stiffness. Similar to muscle stretch reflex action, which is modulated with background activation, these reflexes also show dependence on muscle activation. The potential significance of this reflex stiffness during functional tasks was also discussed. We conclude that reflex activation of knee muscles is sufficient to enhance joint stabilization in the adduction/abduction direction, where knee medial-lateral loading arises frequently during many activities.

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