Prediction Of Maximum Repetitions And Repetitions In Reserve Of A Set From The Barbell Velocity

Purpose:This study is aimed(1)to provide a regression equation that could predict the maximum number of repetitions(XRM)of a set from the mean velocity(MV)of the barbell,and the relative load(1RM%)was used to assist the regression analysis;(2)to find whether the mean velocity(MV)of barbell can be used to determine the repetitions in reserve(RIR)of a set,and the maximum velocity of a set(Vmax),the relative load(%1RM)and the persentage of velocity loss(VL%)was used to assist the regression analysis;(3)To determine the between-sessions reliability of the MV associated with 1RM to 10RM,so as to determine the feasibility of the application of individual XRM-MV relationship into practice.Methods:23 training-experienced PE students of Beijing Sport University(age:20.8±3.2 years;height:181.2±5.7 cm;body mass 76.9±7.1 kg;BMI:23.4± 1.8;training ages 4.2±1.6 years)were recruited to the study,and their 1RM of free weight squat(144.9±19.1 kg)was tested.After that,the subjects were asked to completed four sets of free weight back squat as many repetitions as possible against relative loads of 60%1RM,70%1RM,80%1RM,and 90%1RM over two separate sessions.Then the experimental data were analyzed by repeated measures ANOVA analysis,regression analysis and test-retest reliability analysis.Results:The regression equations of MV and XRM showed good relationships(R2=0.713-0.876),but the MV associated with each XRM showed great betweensubjects variability(CV=8.7%-15.6%).The coefficient of variation between 5RM and 10RM was below 10(CV=8.7%-9.6%),while between 1RM and 4RM the coefficient of variation was higher than 10(CV=10.1%-15.6%).The regression equations of MV and RIR showed moderate relationships(R2=0.570-0.618),while the between-subjects variability of MV associated with each RIR was too high(CV=11.03%18.71%).However,a strong relationship(median R2=0.9726)and acceptable reliability(CV=4.15%-6.62%<10%and ICC>0.77)were observed between the fastest MV of the set and the XRM when considering individual data.Conclusions:These results highlight that generalized group equations are not acceptable methods for estimating the XRM-MV relationships or the number of repetitions in reserve.When attempting to estimate the XRM-MV relationship individualized relationships must be utilized in order to objectively estimate the exact number of repetitions that can be performed in a training set.