EMG activation of abdominal muscles in the crunch exercise performed with different external loads.
OBJECTIVE
The aim of this study was to describe by means of surface electromyography the activation of the rectus abdominis, obliquus externus and rectus femoris muscles during the "crunch" abdominal exercise performed with loads.


METHODS
Thirteen subjects performed crunch exercises with loads representing 80, 60, 40 and 20% of the 1-RM (100%) in a random order with the subjects drawing lots, and with a 5 min rest between sets. Surface bipolar EMG electrodes were used. The root mean square of the EMG was calculated for the first repetition of each load. Differences between conditions were tested using a one way ANOVA for repeated measures. Post-hoc Bonferroni tests was used to detect significant differences between specific loads (p<0.05).


RESULTS
An average of the percentage values of all studied abdominal muscles was used as a representative value of abdominal synergy (Ab Syn). In general it can be concluded that the abdominal muscles were significantly more recruited in the 100% load condition. Abdominal activation significantly differed between the various loads; however, in general adjacent loads (20 vs. 40% - 1-RM) did not differ.


CONCLUSIONS
These results suggest that for young, healthy and physically active adults when the objective is progression in the training process of abdominal force, the option ought to be for changes of load superior to 20% of the 1-RM.
Faculty of Physical Education, University of Campinas, UNICAMP, São Paulo, Brazil. acmoraes@fef.unicamp.br
Antonio C
AC
Moraes
Ronei S
RS
Pinto
Maria Jose
MJ
Valamatos
Maria Joao
MJ
Valamatos
Pedro L
PL
Pezarat-Correia
Alexandre H
AH
Okano
Pedro M
PM
Santos
Jan M
JM
Cabri
D000009:Abdominal Muscles / Q000502:physiology*; D000293:Adolescent; D004576:Electromyography; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult