Purpose:This study aimed to examine the reliability and validity of load-velocity(L-V)relationship variables obtained through the 2-point method using different load combinations and velocity variables.Methods:Twenty ...Purpose:This study aimed to examine the reliability and validity of load-velocity(L-V)relationship variables obtained through the 2-point method using different load combinations and velocity variables.Methods:Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads(20 kg,40 kg,60 kg,and80 kg)and a heavy squat against a load linked to a mean velocity(MV)of 0.55 m/s(load_(0.55)).The L-V relationship variables(load-axis intercept(L_(0)),velocity-axis intercept(v_(0)),and area under the L-V relationship line(A_(line)))were obtained using 3 velocity variables(MV,mean propulsive velocity(MPV),and peak velocity)by the multiple-point method including(20-40-60-80-load_(0.55))and excluding(20-40-60-80)the heavy squat,as well as from their respective 2-point methods(20-load_(0.55)and 20-80).Results:The L-V relationship variables were obtained with an acceptable reliability(coefncient of variation(CV)≤7.30%;intra-class correlation coefficient>0.63).The reliability of L_(0)and v_(0)was comparable for both methods(CV_(ratio)(calculated as higher value/lower value):1.11-1.12),but the multiple-point method provided Al_(ine)with a greater reliability(CV_(ratio)=1.26).The use of a heavy squat provided the L-V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load(CV_(ratio):1.06-1.19).The peak velocity provided the load-velocity relationship variables with the greatest reliability(CV_(ratio):1.15-1.86)followed by the MV(CV_(ratio):1.07-1.18),and finally the MPV.The 2-point methods only revealed an acceptable validity for the MV and MPV(effect size≤0.19;Pearson s product-moment correlation coefficient≥0.96;Lin's concordance correlation coefficient≥0.94).Conclusion:The 2-point method obtained from a heavy squat load and MV or MPV is a quick,safe,and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L-V relationship.展开更多
Based on the CNN-LSTM fusion deep neural network,this paper proposes a seismic velocity model building method that can simultaneously estimate the root mean square(RMS)velocity and interval velocity from the common-mi...Based on the CNN-LSTM fusion deep neural network,this paper proposes a seismic velocity model building method that can simultaneously estimate the root mean square(RMS)velocity and interval velocity from the common-midpoint(CMP)gather.In the proposed method,a convolutional neural network(CNN)Encoder and two long short-term memory networks(LSTMs)are used to extract spatial and temporal features from seismic signals,respectively,and a CNN Decoder is used to recover RMS velocity and interval velocity of underground media from various feature vectors.To address the problems of unstable gradients and easily fall into a local minimum in the deep neural network training process,we propose to use Kaiming normal initialization with zero negative slopes of rectifi ed units and to adjust the network learning process by optimizing the mean square error(MSE)loss function with the introduction of a freezing factor.The experiments on testing dataset show that CNN-LSTM fusion deep neural network can predict RMS velocity as well as interval velocity more accurately,and its inversion accuracy is superior to that of single neural network models.The predictions on the complex structures and Marmousi model are consistent with the true velocity variation trends,and the predictions on fi eld data can eff ectively correct the phase axis,improve the lateral continuity of phase axis and quality of stack section,indicating the eff ectiveness and decent generalization capability of the proposed method.展开更多
Exercise intensity is usually prescribed based on a metabolic marker,such as maximum oxygen uptake or maximal lactate steady state.Those markers,however,face some difficulties regarding their practical applicability t...Exercise intensity is usually prescribed based on a metabolic marker,such as maximum oxygen uptake or maximal lactate steady state.Those markers,however,face some difficulties regarding their practical applicability to the general popula-tion.The critical speed emerges as an alternative parameter to determine aerobic exercise intensities through maximal tests using ergometers or field tests,demanding few resources.We evaluated the fidelity of test to predict critical speed and if this parameter could be used to prescribe intensity in aerobic exercise.One hundred recreational runners performed the T10 test and a conventional critical speed test to define running speeds.Out of them,44 runners proceed continuous and interval races.The critical speed assessed from T10 test was then compared to critical speed measured by three maximal runs in the track field(1200 m,2400 m,and 3600 m).We found a strong correlation(r=0.91)and did not find statistical differences(t=1.8,P=0.90)between critical speed assessed by T10(3.89±0.49 m/s)and field-test(3.85±0.51 m/s).T10 is also better associated with running and interval running speeds than metabolic markers.T10 test can be used as a valid alternative method to assess critical speed and to prescribe runs.展开更多
Microcirculation of the peripheral nerve is necessary for neural growth and regeneration. However, technical limitations have limited studies in this area. The few studies conducted have concerned active exercise effe...Microcirculation of the peripheral nerve is necessary for neural growth and regeneration. However, technical limitations have limited studies in this area. The few studies conducted have concerned active exercise effects on microcirculation of the peripheral nerve. Using an animal experiment, this study evaluated the effect of swimming training on microcirculation of injured peripheral nerve by laser Doppler flowmetry. The results showed that the blood vessel at the distal end of the peripheral nerve was the main blood supply for the nerve, and the internal blood supply for the nerve had strong compensatory ability. Swimming training promoted the functional recovery of rats with sciatic nerve injury and the regeneration of myelin sheath and blood vessels, but had no impact on neural blood flow.展开更多
基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Scie...基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Science、PubMed和中国知网等数据库的有关研究文献,从应用基础和训练效果方面对VBT的研究证据进行梳理和分析。结果显示:①常用的多关节力量训练动作的平均速度/平均推动速度均与%1RM呈强负相关关系,构建的个体速度与%1RM关系模型能使动作速度精确关联%1RM;②速度损失百分比与重复次数百分比呈强正相关关系,能够准确利用两者的关系模型推算特定速度区间的完成次数;③速度损失百分比与疲劳关系紧密,能量化疲劳和刺激水平,控制力量训练中过度疲劳带来的负面效应;④VBT能有效提升力量水平,相比传统力量训练方法,VBT能在疲劳程度和训练量更小的情况下提升运动表现;⑤VBT是实现力量训练科学化的重要途径,相关科学研究和实践应用领域应对其给予更多关注。展开更多
文摘Purpose:This study aimed to examine the reliability and validity of load-velocity(L-V)relationship variables obtained through the 2-point method using different load combinations and velocity variables.Methods:Twenty men performed 2 identical sessions consisting of 2 countermovement jumps against 4 external loads(20 kg,40 kg,60 kg,and80 kg)and a heavy squat against a load linked to a mean velocity(MV)of 0.55 m/s(load_(0.55)).The L-V relationship variables(load-axis intercept(L_(0)),velocity-axis intercept(v_(0)),and area under the L-V relationship line(A_(line)))were obtained using 3 velocity variables(MV,mean propulsive velocity(MPV),and peak velocity)by the multiple-point method including(20-40-60-80-load_(0.55))and excluding(20-40-60-80)the heavy squat,as well as from their respective 2-point methods(20-load_(0.55)and 20-80).Results:The L-V relationship variables were obtained with an acceptable reliability(coefncient of variation(CV)≤7.30%;intra-class correlation coefficient>0.63).The reliability of L_(0)and v_(0)was comparable for both methods(CV_(ratio)(calculated as higher value/lower value):1.11-1.12),but the multiple-point method provided Al_(ine)with a greater reliability(CV_(ratio)=1.26).The use of a heavy squat provided the L-V relationship variables with a comparable or higher reliability than the use of a heavy countermovement jump load(CV_(ratio):1.06-1.19).The peak velocity provided the load-velocity relationship variables with the greatest reliability(CV_(ratio):1.15-1.86)followed by the MV(CV_(ratio):1.07-1.18),and finally the MPV.The 2-point methods only revealed an acceptable validity for the MV and MPV(effect size≤0.19;Pearson s product-moment correlation coefficient≥0.96;Lin's concordance correlation coefficient≥0.94).Conclusion:The 2-point method obtained from a heavy squat load and MV or MPV is a quick,safe,and reliable procedure to evaluate the lower-body maximal neuromuscular capacities through the L-V relationship.
基金financially supported by the Key Project of National Natural Science Foundation of China (No. 41930431)the Project of National Natural Science Foundation of China (Nos. 41904121, 41804133, and 41974116)Joint Guidance Project of Natural Science Foundation of Heilongjiang Province (No. LH2020D006)
文摘Based on the CNN-LSTM fusion deep neural network,this paper proposes a seismic velocity model building method that can simultaneously estimate the root mean square(RMS)velocity and interval velocity from the common-midpoint(CMP)gather.In the proposed method,a convolutional neural network(CNN)Encoder and two long short-term memory networks(LSTMs)are used to extract spatial and temporal features from seismic signals,respectively,and a CNN Decoder is used to recover RMS velocity and interval velocity of underground media from various feature vectors.To address the problems of unstable gradients and easily fall into a local minimum in the deep neural network training process,we propose to use Kaiming normal initialization with zero negative slopes of rectifi ed units and to adjust the network learning process by optimizing the mean square error(MSE)loss function with the introduction of a freezing factor.The experiments on testing dataset show that CNN-LSTM fusion deep neural network can predict RMS velocity as well as interval velocity more accurately,and its inversion accuracy is superior to that of single neural network models.The predictions on the complex structures and Marmousi model are consistent with the true velocity variation trends,and the predictions on fi eld data can eff ectively correct the phase axis,improve the lateral continuity of phase axis and quality of stack section,indicating the eff ectiveness and decent generalization capability of the proposed method.
文摘Exercise intensity is usually prescribed based on a metabolic marker,such as maximum oxygen uptake or maximal lactate steady state.Those markers,however,face some difficulties regarding their practical applicability to the general popula-tion.The critical speed emerges as an alternative parameter to determine aerobic exercise intensities through maximal tests using ergometers or field tests,demanding few resources.We evaluated the fidelity of test to predict critical speed and if this parameter could be used to prescribe intensity in aerobic exercise.One hundred recreational runners performed the T10 test and a conventional critical speed test to define running speeds.Out of them,44 runners proceed continuous and interval races.The critical speed assessed from T10 test was then compared to critical speed measured by three maximal runs in the track field(1200 m,2400 m,and 3600 m).We found a strong correlation(r=0.91)and did not find statistical differences(t=1.8,P=0.90)between critical speed assessed by T10(3.89±0.49 m/s)and field-test(3.85±0.51 m/s).T10 is also better associated with running and interval running speeds than metabolic markers.T10 test can be used as a valid alternative method to assess critical speed and to prescribe runs.
基金the Military Project during "Tenth Five-Year Plan" Period, No.200626Z000058
文摘Microcirculation of the peripheral nerve is necessary for neural growth and regeneration. However, technical limitations have limited studies in this area. The few studies conducted have concerned active exercise effects on microcirculation of the peripheral nerve. Using an animal experiment, this study evaluated the effect of swimming training on microcirculation of injured peripheral nerve by laser Doppler flowmetry. The results showed that the blood vessel at the distal end of the peripheral nerve was the main blood supply for the nerve, and the internal blood supply for the nerve had strong compensatory ability. Swimming training promoted the functional recovery of rats with sciatic nerve injury and the regeneration of myelin sheath and blood vessels, but had no impact on neural blood flow.
文摘基于速度的力量训练(Velocity Based Training,VBT)是利用速度与最大力量百分比(%1RM)、速度与动作重复次数、速度与疲劳的强相关关系,制定、监控和调整力量训练负荷的新方法,具有实时性、准确性和普适性特点。通过系统检阅Web of Science、PubMed和中国知网等数据库的有关研究文献,从应用基础和训练效果方面对VBT的研究证据进行梳理和分析。结果显示:①常用的多关节力量训练动作的平均速度/平均推动速度均与%1RM呈强负相关关系,构建的个体速度与%1RM关系模型能使动作速度精确关联%1RM;②速度损失百分比与重复次数百分比呈强正相关关系,能够准确利用两者的关系模型推算特定速度区间的完成次数;③速度损失百分比与疲劳关系紧密,能量化疲劳和刺激水平,控制力量训练中过度疲劳带来的负面效应;④VBT能有效提升力量水平,相比传统力量训练方法,VBT能在疲劳程度和训练量更小的情况下提升运动表现;⑤VBT是实现力量训练科学化的重要途径,相关科学研究和实践应用领域应对其给予更多关注。
