Changes of the maximum strength potential of elbow flexors in 3 groups of subjects after 3 weeks of exercises with modified muscle contractions

Abstract

The purpose of this study was to assess the changes in the maximal strength potential in elbow flexor muscles of the subjects, following a realised 6-week strength programme of exercises with standard and modified repetitive muscle loads. 51 subjects were placed in 3 groups. The subjects have executed muscle power exercises on Scott bench for the elbow flexor muscles (m.biceps brashii; m.brachialis; m.brachioradialis) on the non-dominant arm, by using barbell weights, and movements with central support in the period of 3 weeks, with 3 sets and 5 minutes breaks in-between. The main task of each subject was to execute as many repetitions as possible until failure. The subjects in the groups have executed movements with reduced muscle contractions. The groups were differentiated in the manner (movement amplitude) of performing the non-dominant arm elbow flexion: E1-matrix method; E2 group – movement amplitude in the zone of half-flexion to maximal flexion of the elbow and vice-versa: E3 group – movement amplitude in the zone of maximal extension to half-flexion and vice-versa. Subjects were tested at the beginning and upon completion of the experiment in the tests: One maximal repetition on Scott bench (kg) (1RM), Maximal dynamometric strength in elbow under angle 90° [kg] (DMAX); Maximal repetition strength with load of 60% on Scott bench (RS60) and angle speed at elbow flexion Scott bench (1RM) rad/sec - (AGOLV). Т- tests were used as statistics to track changes on level 0.05. There are significant changes in the Е1 group for 1RМ, of 6.64% (p<0.01) in the mean value. For E2, significant strength increase is noted by 4.15% (p<0.005), as well as for E3 by 5.67% (p<0.01). The dynamometrical measured static strength of the flexor muscles was not impacted by the experimental programme in a statistically important manner, although the reduction of this component is observed following the 3 weeks of exercise. For the E1 and E3 group, the angle speed test did not present any significant difference between the two tests; however, there is percentage increase of time in seconds (Е1=20.94%; Е3=67.49%). Whereas, for the E2 group, execution was also reduced by 45.36% against the initial value for 1RM; however with statistically significant change (p<0.005). Although the three groups have shown positive transformation of strength endurance in percentage terms, only the E2 group (half to maximal flexion) shows significant changes of 20.79% (p<0.036). Although the subjects did not execute full amplitude, there is still a positive transfer in the maximal strength of elbow flexors. Transformation methods of strength capacity were directed towards the maximal strength capacities; however, this type of exercises also impacts the endurance at manifesting muscle strength. The three weeks of exercises were sufficient for the occurrence of early transformation of the maximal strength of elbow flexor muscles.