Objective To explore the effect of exercise-induced fatigue on intra-and interhemispher-ic functional connectivity of the primary motor cortex during unilateral ankle plantar-dorsiflexion.Meth-ods Twenty-four healthy adult males(age:21.6±2.2 years;all right-side dominant)were selected as participants for the study.They ran on a treadmill at an individualized constant speed until fatigue.Fatigue was determined when all the following criteria were met:(1)participants failing to maintain the individualized constant speed despite the strong verbal encouragement from the experimenters;(2)reaching a rating of perceived exertion(RPE)score of at least 19;and(3)their heart rate reaching 90%of their age-predicted maximal heart rate(220-age).Moreover,EEG signals from four channels(C1,C2,C3,and C4)of the primary motor cortex were collected during unilateral ankle dorsi-plan-tarflexion movements before and after fatigue,followed by EEG coherence analyses on the collected da-ta.Results Compared to the pre-fatigue state,the coherence values of the intra-hemispheric primary motor cortex electrode pairs C1-C3 and C2-C4 during unilateral ankle plantar-dorsiflexion decreased significantly in the alpha and gamma bands after fatigue(both P<0.05).Conversely,the value of the interhemispheric primary motor cortex electrode pair C1-C2 increased significantly in the beta band(P<0.05).Conclusion Exercise-induced fatigue significantly weakens the intra-hemispheric functional con-nectivity of the primary motor cortex during unilateral ankle plantar-dorsiflexion.However,it may en-hance the interhemispheric functional connectivity and potentially collaborate to strengthen the regula-tion of fatigued muscles.

Objective To explore the effect of exercise-induced fatigue on intra-and interhemispher-ic functional connectivity of the primary motor cortex during unilateral ankle plantar-dorsiflexion.Meth-ods Twenty-four healthy adult males(age:21.6±2.2 years;all right-side dominant)were selected as participants for the study.They ran on a treadmill at an individualized constant speed until fatigue.Fatigue was determined when all the following criteria were met:(1)participants failing to maintain the individualized constant speed despite the strong verbal encouragement from the experimenters;(2)reaching a rating of perceived exertion(RPE)score of at least 19;and(3)their heart rate reaching 90%of their age-predicted maximal heart rate(220-age).Moreover,EEG signals from four channels(C1,C2,C3,and C4)of the primary motor cortex were collected during unilateral ankle dorsi-plan-tarflexion movements before and after fatigue,followed by EEG coherence analyses on the collected da-ta.Results Compared to the pre-fatigue state,the coherence values of the intra-hemispheric primary motor cortex electrode pairs C1-C3 and C2-C4 during unilateral ankle plantar-dorsiflexion decreased significantly in the alpha and gamma bands after fatigue(both P<0.05).Conversely,the value of the interhemispheric primary motor cortex electrode pair C1-C2 increased significantly in the beta band(P<0.05).Conclusion Exercise-induced fatigue significantly weakens the intra-hemispheric functional con-nectivity of the primary motor cortex during unilateral ankle plantar-dorsiflexion.However,it may en-hance the interhemispheric functional connectivity and potentially collaborate to strengthen the regula-tion of fatigued muscles.

Objective To investigate the effects of high-definition transcranial direct current stimulation(HD-tDCS)on the modulation of the H-reflex and M-wave during ankle dorsiflexion-plantar flexion fatigue tasks to provide direction for the application of HD-tDCS in mitigating neuromuscular fatigue.Methods Twenty healthy young male participants were recruited and randomly assigned to either the real stimulation or sham stimulation group,with 10 participants in each group.The intervention consisted of a 5-day single-blind HD-tDCS application(duration:20 min;intensity:2 mA;target:Cz).Baseline measurements of the H-reflex and M-wave under resting conditions,M-wave during maximal voluntary isometric contraction(MVIC)of the dorsiflexor muscle,and MVIC torque of the dorsiflexor and plantar flexor muscles were obtained.An ankle dorsiflexion fatigue task was performed to determine the time to achieve fatigue for the task.The same fatigue task was repeated and evaluated one day after the intervention.A repeated-measures two-factor(stimulation condition x pre/post fatigue)analysis of variance(ANOVA)was used to analyze the effects of independent variables on the mechanical properties of the muscles and α-motoneuron conduction characteristics.Results After fatigue,voluntary activation(VA),maximal H-reflex(Hmax),maximal M-wave(Mmax),and dorsiflexor and plantar flexor MVIC torques in both groups were significantly reduced compared with pre-fatigue levels(P＜0.05).However,compared to the real stimulation group,the sham stimulation group showed a more significant decline in VA and plantar flexor MVIC torque(P＜0.05).Conclusions A continuous 5-day HD-tDCS intervention can effectively increase α-motoneuron activity at the spinal segment.It can also exert an inhibitory effect on reducing information transmission capacity at the peripheral neuromuscular junction under the ankle dorsi-plantarflexion fatigue task.

Sports fatigue of the lower limbs is one of the important factors affecting sports performance. How to improve the anti-fatigue ability of the lower limbs during endurance exercise is the focus of the research field of human sports biomechanics. This study systematically reviewed the relevant literature on transcranial direct current stimulation (tDCS) intervention on lower limb endurance performance, summarized the effect of tDCS on lower limb endurance performance, and analyzed the influencing factors and potential mechanisms. The results showed that: tDCS intervention has a significant effect on the endurance performance of the whole lower limbs, but there is no unified conclusion on the effect on the endurance performance of the knee joint. The researchers deem that tDCS can increase the excitability of the primary motor cortex and reduce the activation of the supplementary motor area and the premotor area to producing a lower rating of perceived exertion, but cannot affect the perception of exercise-induced pain, and stimulation protocols varied across studies, which may be partly responsible. This study can provide a theoretical basis for exploring the central mechanism of tDCS to improve endurance performance, formulating rehabilitation and sports training programsfor different groups of people, and developing new stimulation equipment to enhance the human body’s anti fatigue ability.

Objective To establish the reference intervals of hemoglobin A 1c( HbA1c ) and fasting plasma glucose ( FPG ) in the first and second trimester of pregnancy in Chongqing , and to evaluate the viability of the combination of HbA 1c and FPG in screening gestational diabetes mellitus (GDM).Methods The study retrospectively selected the pregnant women seen at the Department of Obstetrics and Gynecology in Daping Hospital between September 2014 and August 2015.The results of FPG during 10-13 pregnant weeks and 75 g oral glucose tolerance test ( OGTT ) and HbA1c during 24-28 pregnant weeks were available.Totally 185 cases were assigned into GDM group , and 269 cases were assigned into normal group based on the American Diabetes Association ( ADA) guidelines.Reference intervals of HbA 1c and FPG in normal pregnant woman were developed .The difference of HbA 1c , FPG and OGTT results between two groups was analyzed.T-student test, NcMemar test,signed rank sum test, ROC curve were used for statistical analysis.Results The reference intervals of HbA 1c and FPG in first and second trimester were 4.58%-5.52%,4.21-5.49 mmol/L and 4.03-5.08 mmol/L.The FPG level in first and second trimester and HbA 1c level in GDM group vs normal group were(5.06 ±0.37) vs(4.85 ±0.32)mmol/L(t=6.569,P=0.000), 5.23(5.11,5.4) vs 4.74(4.54,4.91) mmol/L(z=-14.31,P=0.000)and 5.3(5.1,5.4)% vs 5.2(5.0, 5.3)%( z=-5.79,P=0.000) respectively.The area under receiver operating characteristic curve ( ROC) of HbA1c , and FPG in first and second trimester was 0.655, 0.659 and 0.890 respectively.When the cut-off value of HbA1c was 5.35%, the AUC of the combination of HbA 1c and FPG in second trimester was 0.898, the sensitivity was 0.838,and the specificity was 0.859.The kappa coefficient for identifying GDM between OGTT and the combined method was 0.692(P=0.000).Conclusion HbA1c combined with FPG is of some value in screening GDM.