Welcome to the Podiatry Arena forums, for communication between foot health professionals about podiatry and related topics.
You are currently viewing our podiatry forum as a guest which gives you limited access to view all podiatry discussions and access our other features. By joining our free global community of Podiatrists and other interested foot health care professionals you will have access to post podiatry topics (answer and ask questions), communicate privately with other members (PM), upload content, view attachments, receive a weekly email update of new discussions, earn CPD points and access many other special features. Registered users do not get displayed the advertisments in posted messages. Registration is fast, simple and absolutely free so please, join our global Podiatry community today!
If you have any problems with the registration process or your account login, please contact contact us.
The effect of lower extremity fatigue on shock attenuation during single-leg landing
Evan Coventry, Kristian M. O’Connor, Barbara A. Hart, Jennifer E. Earl, Kyle T. Ebersole Clinical Biomechanics (in press)
Quote:
Background
The forces that are imposed on the body due to landings must be attenuated primarily in the lower extremity. Muscles assist in the absorption of these forces, and it has been shown that a fatigued muscle decreases the body’s ability to attenuate shock from running. The purpose of the study was to determine the effect of lower extremity fatigue on shock attenuation and joint mechanics during a single-leg drop landing.
Methods
Ten active male participants were recruited (eight used for analysis). Each participant took part in a fatigue landing protocol. This protocol included cycles of a drop landing, a maximal countermovement jump, and five squats, repeated until exhaustion. Accelerometers attached to the skin measured tibia and head accelerations. Lower extremity kinematics were collected using an electromagnetic tracking system and kinetics were collected using a forceplate. A repeated-measures ANOVA (P<0.05) was performed on each of the dependent variables across the cycles of the fatigue protocol.
Findings
Fatigue was induced, however there was no significant change in shock attenuation throughout the body. Hip and knee flexion increased and ankle plantarflexion decreased at touchdown with fatigue. Hip joint work increased and ankle work decreased.
Interpretation
This change in work distribution is thought to be a compensatory response to utilize the larger hip extensors that are better suited to absorb the mechanical energy of the impact. The results suggested that the lower extremity is able to adapt to fatigue though altering kinematics at impact and redistributing work to larger proximal muscles.
The effect of lower extremity fatigue on shock attenuation during single-leg landing
Evan Coventry, Kristian M. O’Connor, Barbara A. Hart, Jennifer E. Earl, Kyle T. Ebersole Clinical Biomechanics (in press)
There is currently no consensus in the literature on whether the magnitude of the ground reaction force or loading rate decreases or increases with muscle fatigue. In this article, the effects of lower extremity muscle fatigue on the magnitude of the ground reaction force and loading rate during running and drop landing are examined. Through a systematic search of the literature, 24 articles are identified that satisfy the inclusion criteria and study the relationship between fatigue and the ground reaction force variables during running, single-leg drop landing, and bilateral drop landing. The articles are categorized based on the type of locomotion they study. To determine whether or not the ground reaction force peaks/loading rate are markedly affected by fatigue, meta-analyses are conducted both separately for each type of locomotion and for an aggregate of all studies. The results of the meta-analyses show that the ground reaction force active peak significantly decreases for the following study groups: aggregate of all included studies, studies of drop landing (both single-leg and bilateral), and studies of bilateral landing only. The ground reaction force active peak did not significantly change in running and single-leg drop landing. The effects of muscle fatigue on the magnitude of the ground reaction force impact peak and loading rate was always insignificant.
Decreased foot inversion force and increased plantar surface after maximal incremental running exercise
Bruno Vie, Christelle Brerro-Saby, Jean Paul Weber, Yves Jammes Gait & Posture; Article in Press
Quote:
Formulating the hypothesis that a maximal running exercise could induce fatigue of some foot muscles, we searched for electromyographic (EMG) signs of fatigue in the tibialis anterior (TA), peroneus longus (PL), and gastrocnemius medialis (GM) muscles. We also searched for post-exercise alterations of the stationary upright standing in normal-arched feet subjects.
Healthy subjects performed a maximal running exercise. Surface EMGs of the TA, PL, and GM muscles were analysed during maximal dynamic efforts. Before and after the running bout, we measured the evoked compound muscle potential (M-wave) in TA, the maximal force into inversion (MIF), and the repartition of the plantar and barycentre surfaces with a computerised stationary platform.
During maximal running exercise, the median frequency of the EMG spectra declined in TA while it remained stable in the PL and GM muscles. After the exercise, MIF decreased, and both the rearfoot plantar surface and the barycentre surface increased.
We concluded that a maximal running bout elicits EMG signs of fatigue, though only in the TA muscle. It also elicits post-exercise changes in the foot position during stationary upright standing which indicates a foot eversion. These data solely concern a maximal running test and they can not be extrapolated to walking or running at a low speed.
Quote:
Highlights
► We hypothesised that maximal running could induce fatigue of some foot muscles.
► Surface electromyograms (EMG) of three foot muscles were recorded during running.
► We measured maximal foot inversion force and repartition of the plantar surfaces.
► EMG signs of fatigue were measured in a foot invertor muscle (tibialis anterior)
► Running elicited post-exercise foot eversion during stationary upright standing.
Effect of Functional Fatigue on Vertical Ground Reaction Force Among Individuals with Flat Feet.
Boozari S, Jamshidi AA, Sanjari MA, Jafari H. J Sport Rehabil. 2013 Mar 8.
Quote:
CONTEXT:
Flat foot as one of the lower extremity deformities might change kinetic variables of gait. Fatigue is one of the factors which can alter the vertical ground reaction force (GRF). Effect of fatiguing condition on vertical GRF was not documented in individuals with flat feet.
OBJECTIVE:
To examine the fatigue effect on vertical GRF in individuals with flat feet compared with a normal group during barefoot walking.
DESIGN:
Repeated measure ANOVA for the effects of fatigue on individuals with flat feet and normal feet.
SETTING:
Biomechanics laboratory.
PARTICIPANTS:
Seventeen subjects with flat feet and 17 normal subjects (recruited according to their arch height ratio) completed the test.
MAIN OUTCOME MEASURES:
Three vertical GRF measures (F1; the first peak force, F2; minimum force; and F3; the second peak force) were extracted before and after a functional fatigue protocol.
RESULTS:
No significant interaction between fatigue and group was observed for the three vertical GRF measures. For F2, fatigue and group effects were significant (p = 0.001 and p = 0.02, respectively). Furthermore, F2 was higher in the flat feet group compared with the normal group; F2 also increased after fatigue. For F3, only a significant fatigue effect was observed (p = 0.004). F3 decreased after fatigue in both groups.
CONCLUSIONS:
In the flat feet group, a decrease in the variation of vertical GRF might be due to more flexible foot joints. After fatigue, muscles might lose their ability to control the foot joints and cause higher F2 in the flat feet group.
We analyzed gait and function of the supporting limb in participants of a marathon race at three stages: prerace, midrace (18 km), and near the end of the race (36 km). We confirmed that the most successful runners were able to maintain running speed for the duration of the race with little change in speed or gait. Speed slowed progressively during the race for those with slower race times, but stride frequency–stride length relationships remained normal for the speed they ran. These findings differ from most lab-based studies of fatigue, in which runners are forced to match a constant preset treadmill speed. Small changes in maximum ground force were seen in both slow- and fast-running participants as race end approached.
Shock absorption when fatigued
Linear Mode
