Systematic reduction of leg muscle activity throughout a standard assessment of running footwear

Purpose This study aimed to investigate whether there is a systematic change of leg muscle activity,as quantified by surface electromyography(EMG),throughout a standard running footwear assessment protocol at a predetermined running speed.Methods Thirty-one physically active adults(15 females and 16 males)completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s.The level of muscle activity from 6 major leg muscles was recorded using surface EMG.The variables assessed were the EMG total intensity as a function of time and the cumulative EMG overall intensity.Systematic effects of the chronological testing round(independent variable)on the normalized EMG overall intensity(dependent variable)were examined using Friedman analysis of variates and post hoc pairwise Wilcoxon signed-rank tests(α=0.05).Results There was a systematic reduction in overall EMG intensity for all 6 muscles over the time course of the running protocol(p<0.001)until the fourth testing round when EMG intensities reached a steady state.The one exception was the biceps femoris muscle,which showed a significant reduction of EMG intensity during the stance phase(p<0.001)but not the swing phase(p=0.16).Conclusion While running at a predetermined speed,the neuromuscular system undergoes an adaptation process characterized by a progressive reduction in the activity level of major leg muscles.This process may represent an optimization strategy of the neuromuscular system towards a more energetically efficient running style.Future running protocols should include a familiarization period of at least 7 min or 600 strides of running at the predetermined speed.

Effect of Exercise with Rhythmic Auditory Stimulation on Muscle Coordination and Gait Stability in Patients with Diabetic Peripheral Neuropathy: A Randomized Controlled Trial

Background: Diabetic peripheral neuropathy (DPN) changes leg muscle coordination during walking and reduces stability. The aim of this study was to determine whether rhythmic auditory stimulation (RAS) affected the gait performance of patients with DPN. Methods: Forty DPN patients (mean age, 59.1 ± 9.4 y) were randomly allocated to RAS and control groups in equal numbers. The participants in each group underwent 2 weeks of supervised rehabilitative treatment (40 min/day) as inpatients. This included walking twice a day, during which the RAS group participants walked in time with a metronome set at a self-chosen, comfortable rate. We compared gait function, lower limb muscle co-contraction, and gait stability before and after the intervention for both groups, calculated the change in score for each parameter, and assessed differences between the groups with unpaired t-tests and ANCOVA. Results: RAS was associated with significant improvement in all parameters. In the control group, there was no improvement in cadence, co-contraction, or gait stability (vertical). Compared with the control group, the RAS group showed improvement in co-contraction and gait stability. Conclusion: RAS may be helpful for improving the lower limb muscle coordination and gait function of DPN patients.

Differences in Kinetics,Kinematics and Muscle Activation Strategies in Male and Female Team Sport Athletes During Unanticipated Sidestepping

Purpose The purpose of this study was to compare kinetics,kinematics and muscle activation strategies between male and female collegiate level athletes during unanticipated sidestepping tasks to further the understanding of sex-specific differ-ences in injury incidence and their potential influence on ACL injury risk.Methods Three-dimensional kinematics,ground reaction forces and surface electromyography of eight lower limb muscles were recorded during unanticipated sidestepping in 20 male soccer and 17 female field hockey National Collegiate Athlet-ics Association Division 1 athletes.Trunk,hip and knee kinematics,knee joint moments,total muscle activation(TMA:knee,gluteal,quadriceps,hamstrings and gastrocnemii)and directed co-contraction ratios(DCCR)were compared between groups with two-sample t tests.Results No sex differences were observed for peak frontal and transverse plane knee moments(P>0.05),however males had 10%greater knee flexion moments(P=0.047).Females had lower hip flexion and abduction and greater hip internal rota-tion angles than males likely concomitant with the 30%reduction in gluteal TMA(P<0.05).Females had lower quadriceps TMA during pre-contact and weight acceptance and higher hamstrings TMA during weight acceptance(P<0.05).Group averages for DCCR were not representative of individual patterns,where the majority of males were quadriceps dominant compared with females.Conclusions Female and male team sport athletes display similar frontal and transverse plane knee moments,however their ability to support/counter the load applied(i.e.,muscle activations strategies)to the knee joint differed.