It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortali...It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation-the transient period between the quiet standing posture and steady state walking-is a functional task that is classically used in the literature to investigate how the central nervous system(CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a prerequisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on:(1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and(2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward:(1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and(2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices.展开更多
Purpose:To observe the relative change in foot-strike pattern,pressure characteristics,surface electromyography(sEMG) recordings,and stride characteristics in forefoot strike runners wearing both minimalist and tradit...Purpose:To observe the relative change in foot-strike pattern,pressure characteristics,surface electromyography(sEMG) recordings,and stride characteristics in forefoot strike runners wearing both minimalist and traditional shoes during a 50-km run.Methods:Four experienced minimalist runners were enrolled in this study.Each runner ran a 50-km simulated run in both minimalist shoes and traditional shoes.Pressure data,sEMG recordings,and limited 3D motion capture data were collected during the initial 0.8 km and final 0.8 km for each trial.Results:Three runners in the traditional shoe type condition and one runner in the minimalist shoe type condition demonstrated a more posterior initial contact area(midfoot strike(MFS) pattern) after the 50-km run.which was supported by increased activity of the tibialis anterior in the pre-contaet phase(as per root mean square(RMS) values).In addition,in both pre- and post-run conditions,there were increased peak pressures in the minimalist shoe type,specifically in the medial forefoot.Muscle fatigue as defined by a decreased median frequency observed in isometric,constant force contractions did not correspond with our hypothesis in relation to the observed foot strike change pattern.Finally,step rate increased and step length decreased after the 50-km run in both shoe type conditions.Conclusion:More runners adopted a more posterior initial contact area after the 50-km run in the traditional shoe type than in the minimalist shoe type.The runners who adopted a more posterior initial contact area were more closely associated with an increased median frequency of the medial gastrocnemius,which suggests there may be a change in motor unit recruitment pattern during long-distance,sustained velocity running.The increased peak pressures observed in the medial forefoot in the minimalist shoe type may predispose to metatarsal stress fractures in the setting of improper training.展开更多
文摘It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation-the transient period between the quiet standing posture and steady state walking-is a functional task that is classically used in the literature to investigate how the central nervous system(CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a prerequisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on:(1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and(2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward:(1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and(2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices.
基金the Medical College of Wisconsin's Department of Physical Medicine & Rehabilitation,as well as by grant 1UL1RR031973 from the Clinical and Translational Science Award(CTSA)program of the National Center for Research Resources,National Institutes of Health
文摘Purpose:To observe the relative change in foot-strike pattern,pressure characteristics,surface electromyography(sEMG) recordings,and stride characteristics in forefoot strike runners wearing both minimalist and traditional shoes during a 50-km run.Methods:Four experienced minimalist runners were enrolled in this study.Each runner ran a 50-km simulated run in both minimalist shoes and traditional shoes.Pressure data,sEMG recordings,and limited 3D motion capture data were collected during the initial 0.8 km and final 0.8 km for each trial.Results:Three runners in the traditional shoe type condition and one runner in the minimalist shoe type condition demonstrated a more posterior initial contact area(midfoot strike(MFS) pattern) after the 50-km run.which was supported by increased activity of the tibialis anterior in the pre-contaet phase(as per root mean square(RMS) values).In addition,in both pre- and post-run conditions,there were increased peak pressures in the minimalist shoe type,specifically in the medial forefoot.Muscle fatigue as defined by a decreased median frequency observed in isometric,constant force contractions did not correspond with our hypothesis in relation to the observed foot strike change pattern.Finally,step rate increased and step length decreased after the 50-km run in both shoe type conditions.Conclusion:More runners adopted a more posterior initial contact area after the 50-km run in the traditional shoe type than in the minimalist shoe type.The runners who adopted a more posterior initial contact area were more closely associated with an increased median frequency of the medial gastrocnemius,which suggests there may be a change in motor unit recruitment pattern during long-distance,sustained velocity running.The increased peak pressures observed in the medial forefoot in the minimalist shoe type may predispose to metatarsal stress fractures in the setting of improper training.
