| Background and purpose:The maximum muscle strength is the foundation of other power quality, andplays an important role in the development of other power quality. One RepetitionMaximum is operationally defined as the heaviest load that can be moved over aspecific range of motion, one time and with correct performance. It is often on behalfof maximum muscle strength, and commonly used to develop as the standard ofstrength training load to athlete and the public, and used to National Physical FitnessHealth Evaluation as a test indicator of force. The procee of traditional1RM test iscumbersome steps and time-consuming, and appliying to the crowd with no trainingexperience are prone to damage particularly. Therefore, traditional1RM strength testis not easy to be used largely-scale, highly-frequency. Many foreign scholars hadestablished prediction equations with simple measurements to compensate for thelack of1RM test, and which greatly increased the scope of application of1RM. Atpresent,1RM prediction equation is still lacking in our country, there may be someerrors if quoted foreign equation directly. Therefore, the purpose of this study isselecting our young adults as research objects in reference to the basis of foreignresearch achievements, choosing1RM strength of bench press, squat and biceps curlas the dependent variable, the sub-maximum load and the corresponding numbers ofcompleted, the general morphology indicators (height, weight, circumference, etc.)and simple static strength indicators (left and right grip strength, back strength, legstrength) as independent variables in order to establish1RM prediction equations,providing an important method in accordance with evaluation of the1RM simplyand accurately.Methods:The subjects in this study contains240healthy untrained young adults(18-27year-old,124males and116females), each subject should test general morphologyindicators, simple static strength indicators (grip strength, leg strength and back strength) and1RM and4-10RM strength of bench press, squat and biceps curl. Eachsubject participated in two weeks (2-3times/week) practice sessions, familiar withthe testing process and exercises technique; Two weeks later,32subjects wererandomly selected for1RM repetitive test; New prediction equations werereturn-tested by a independent sample of38young subjects and a independentsample of45middle-aged subjects. The data using SPSS16.0statistical software forprocessing, expressed as mean±standard deviation. The actual1-RM as thedependent variable respectively, sub-maximum strength (4-10RM) and completedrepetitions, the general morphology indicators and simple static strength indicatorsas independent variables, using linear regression to establish the prediction equations;Pearson correlation analysis of subjects morphology indicators, simple static strengthindicators between the actual1RM value; The interclass correlation (ICC) is used toexamine the1RM test repeatability; Using paired T-test analysis to compare foreignequations and new equations produced predicted1-RM difference between the actual1-RM value, the significance level P <0.05.Results:1. The ICC coefficient between two tests of the three exercises (Bench press,squat，biceps curl) are highly, both male and female in turn are as follows:0.932,0.986,0.928and0.961,0.988,0.962.2. The result of determining the accuracy of foreign equation for our youths: Inmale subjects, only Brzyck and Lombardi prediction equation produced predicted1-RM values are no significantly different from the actual1-RM performances. Infemale subjects, only Epley and Wathan prediction equation produced predicted1-RM values are no significantly different from the actual1-RM performances.3. Maximum load and completed repetitions as the independent variables,1RMprediction equations are as follows:Males:1RMbench press=rep wt/(0.983-0.021*reps) R~2=0.962;1RMsquat=rep wt/(0.977-0.019*reps) R~2=0.987;1RMbiceps curl=rep wt/(0.976-0.022*reps) R~2=0.989;Females:1RMbench press=rep wt/(0.964-0.021*reps) R~2=0.964; 1RMsquat=rep wt/(0.964-0.018*reps) R~2=0.983;1RMbiceps curl=rep wt/(0.972-0.023*reps) R~2=0.969.Young adults re-test results: All the new prediction equations of young adultsubjects, the relationship between predicted1RM and actual values is high (r=0.982,0.999,0.988;0.990,0.993,0.910), there is no significant difference (p>0.05).Middle-aged subjects re-test results: In all the new prediction equation, therelationship between predicted1RM and actual values is high(r=0.953,0.971,0.933;0.983,0.987,0.918), but for the prediction equations of the female benchpress, other exercises new equation produced predicted1-RM values that are notsignificantly different from the actual1-RM performances (p>0.05).4. The general morphology of indicators as the independent variables，1RMprediction equations are as follows:Males：1RMbench press=6.345*Upper arm tension Cir-3.740*Upper arm relaxed Cir-26.742;1RMsquat=3.164*Weight-3.321*Hip Cir-2.236*Thigh Cir+280.305;1RMbiceps curl=1.299*Upper arm tension Cir-0.524*Calf Cir+12.543;Females:1RMbench press=5.532*Upper arm tension Cir-4.462*Upper arm relaxed Cir+1.197;1RMsquat=1.774*Thigh Cir+9.022*(Upper arm tension Cir-relaxed Cir)-47.186;1RMbiceps curl=0.576*Calf Cir+2.339*(Upper arm tension Cir-relaxed Cir)-3.401.R~2as follpws:0.562,0.389,0.407;0.166,0.196,0.267.Re-test results: In three prediction equations of male subjects, the relationshipbetween predicted1RM and actual values is moderate (r=0.690,0.596,0.422), thereis no significant difference (p>0.05). In bench press and biceps curl predictionequations of male subjects, the relationship between predicted1RM and actualvalues is moderate (r=0.417,0.547), there is no significant difference (p>0.05). Insquat prediction equations, the relationship between predicted1RM and actualvalues is reduced slightly (r=0.16), and there is significant difference (p <0.05).5. Simple static strength indicators as the independent variables,1RMprediction equations are as follows: Males:1RMbench press=0.990*Left grip+11.292R2=0.421;1RMsquat=0.050*Back strength+0.890*Left grip+1.322R2=0.452;1RMbiceps curl=0.211*Left grip+0.006*Leg strength+11.339R2=0.429;Females:1RMbench press=1.029*Right grip+8.004R2=0.431;1RMsquat=0.032*Back strength+0.875*Right grip+13.625R2=0.353;1RMbiceps curl=0.352*Left grip+10.598R2=0.282.Re-test results: In male subjects, three exercises prediction equations producedpredicted1-RM values are moderately related with the actual1-RM performance(r=0.550,0.584,0.629), but for the bench press prediction equations, the otherexercise new equations produced predicted1-RM values that are not significantlydifferent from the actual1-RM performance (p>0.05). In bench press and biceps curlprediction equations of male subjects, the relationship between predicted1RM andactual values is moderate (r=0.672,0.632), there is no significant difference (p>0.05).In squat prediction equations, the relationship between predicted1RM and actualvalues is reduced slightly (r=0.449), and there is significant difference (p <0.05).Conclusions:1. The results of the cross-validations display that foreign prediction equationsapplied to Chinese, reliability declines.2. The maximum load and number of repetitions as independent variable toestablish1RM new prediction equations, R Squared is high, the youth participantsre-test to verification of its reliability shows great, it can be used to projection the1RM strength of the youth population simply and accuratly; middle-aged subjectsre-test to verification, the equation can be used in1RM strength evaluation of therelevant population, but for female bench press.3. The general morphology indicators as the independent variables to establish1RM prediction equation, R Squared is relatively low, especially in the femaleequation. Re-test to verification of its reliability shows good in male subjects, andsuggested that the female should not make morphology indicators to projection1RM.4. The simple static strength indicators as the independent variables to establish 1RM new prediction equation, R Squared is general. Re-test to verification of itsreliability shows good, it is recommended that new prediction equation maybe usedto evaluation1RM strength, but for the male bench press and female squat. |
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