Linearly optimum seeking K-value in the fitting of exponential and geometric curves

Based on logarithmic transformation of exponential and geometric curves, the paper proposes a method of choosing k-value to improve the goodness of fit. Functions between the sum of squares of regression(SSR) and k-value are built up; and the maximum of SSR value can be solved by derivation in which an iterative algorithm is used. A computer program has been developed for application. The result shows that the method is simple, and the goodness of fit is not inferior to other optimum methods of curve fitting.

Chronic training status affects muscle excitation of the vastus lateralis during repeated contractions

This study examined electromyographic amplitude(EMGRMS)-force relationships during repeated submaximal knee extensor muscle actions among chronic aerobically-(AT),resistance-trained(RT),and sedentary(SED)individuals.Fifteen adults(5/group)attempted 20 isometric trapezoidal muscle actions at 50%of maximal strength.Surface electromyography(EMG)was recorded from vastus lateralis(VL)during the muscle actions.For the first and last successfully completed contractions,linear regression models were fit to the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments,and the b terms(slope)and a terms(antilog of y-intercept)were calculated.EMGRMS was averaged during steady force.Only the AT completed all 20 muscle actions.During the first contraction,the b terms for RT(1.3010.197)were greater than AT(0.9100.123;p?0.008)and SED(0.9120.162;p?0.008)during the linearly increasing segment,and in comparison to the linearly decreasing segment(1.0180.139;p?0.014),respectively.For the last contraction,the b terms for RT were greater than AT during the linearly increasing(RT?1.3730.353;AT?0.8830.129;p?0.018)and decreasing(RT?1.5260.328;AT?0.9700.223;p?0.010)segments.In addition,the b terms for SED increased from the linearly increasing(0.9680.144)to decreasing segment(1.2680.126;p?0.015).There were no training,segment,or contraction differences for the a terms.EMGRMS during steady force increased from the first-([64.0851.68]μV)to last-contraction([86.7349.55]μV;p?0.001)collapsed across training statuses.The b terms differentiated the rate of change for EMGRMS with increments in force among training groups,indicating greater muscle excitation to the motoneuron pool was necessary for the RT than AT during the linearly increasing and decreasing segments of a repetitive task.