Effects of concentric and eccentric contractions on strength, retention and bilateral transfer
McDonald, Calvin Edward
Master of Science
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The purpose of this study was to examine the effects of two different strength training methods, (concentric and eccentric) on strength, retention and bilateral transfer. Subjects were 22 male volunteers, aged 16 to 17. Subjects were randomly assigned to one of two treatment groups and to exercise the left or right elbow flexor - extensors. Following a preliminary training and safety period the subjects were pre-tested on the four dependent variables static flexion, static extension, dynamic flexion and dynamic extension at multiple angles of 90, 105, 120, and 135 degrees. The groups alternated each week training Monday, Wednesday and Friday while the other group trained Tuesday and Thursday. Both groups performed 3x6 RM at a velocity of 7.2 revolutions per minute. The instrumentation designed by the investigator was used for training and testing. The non-trained arm remained in a standardized position during training and testing. Subjects were assessed for strength at the beginning of a 6 week training program, at the conclusion of training and after a 4 week retention period. Data were analyzed with a four-way split plot ANOVA, t-tests and percentage changes. The statistical index was represented by the higher score of two trials. An alpha level of .05 was accepted for all statistical procedures. Results showed: (a) strength training methods (concentric and eccentric) improved static and dynamic strength, (b) a significant difference was demonstrated amon^ test angles, (c) specificity between static and dynamic testing procedures was present on a percentage basis, (d) there was a wide range of response among subjects to the exercise regimen, (e) eccentric tension was greater than concentric or isometric tension, (f) neither strength training method was superior to the Other, (g) following 4 weeks of detraining neither training procedure resulted in a significant loss of strength, (h) neither training procedure resulted in a significant transfer of strength and (i) the trained arm was superior to the non-trained arm on the 4 test items.