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The Journal of Sports Medicine and Physical Fitness 1999 September;39(3):253-8

lingua: Inglese

Comparison of two abdom­i­nal train­ing devic­es with an abdom­i­nal ­crunch ­using ­strength and EMG meas­ure­ments

Demont R. G. 1, Lephart S. M. 1, Giraldo J. L. 1, Giannantonio F. P. 1, Yuktanandana P. 3, Fu F. H. 2

1 Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA, USA;
2 Department of Orthopaedics, University of Pittsburgh Medical System, Pittsburgh, PA, USA;
3 Department of Orthopaedics, Chulalongkorn University, Bangkok, Thailand


Background. The pur­pose of ­this ­study was to com­pare the train­ing ­effects of the Ab-Flex (F), Ab-Roller (R) and stan­dard ­crunch (C) on EMG pro­duc­tion, iso­met­ric max­i­mum vol­un­tary con­trac­tion (MVC), and iso­ki­net­ic aver­age ­peak ­torque at 30°/sec (ISO) of the abdom­i­nal mus­cles. It was hypoth­e­sized ­that the train­ing devic­es ­would ­have sim­i­lar val­ue in a ­strength train­ing pro­gram.
Methods. Experimental design: this was a pros­pec­tive ­study involv­ing 18 train­ing ses­sions of pro­gres­sive­ly increas­ing rep­e­ti­tions. Setting: Neuromuscular Research Laboratory, University of Pittsburgh. Subjects: thirty-two sub­jects vol­un­teered for ­this ­study, but ­only 26 com­plet­ed the train­ing. Each sub­ject par­tic­i­pat­ed in rec­re­a­tion­al activ­ity, but had not per­formed any abdom­i­nal train­ing ­prior to start­ing ­this ­study. Each sub­ject was ran­dom­ly ­assigned to ­either the con­trol ­group or one of the treat­ment ­groups. Interventions: there ­were ­three inter­ven­tions: two train­ing devic­es (Ab-Flex and Ab-Roller) and the stan­dard ­crunch, con­sid­ered a con­trol ­group. Measures: the pretest con­sist­ed of ­skin ­fold meas­ure­ments (%), EMG activ­ity (V) dur­ing the ­three inter­ven­tions, and ­peak ­torque (Nm) ­plus EMG dur­ing the MVC and ISO ­tasks. The 18 train­ing ses­sions ­over ­three ­weeks con­sist­ed of ­three ­sets of exer­cise ­with increas­ing rep­e­ti­tions ­from 10 to 20, by 2, eve­ry ­three ses­sions. The dif­fer­ence in ­pretest/­post­test ­scores ­were com­pared ­using a One-way ANO­VA on the ­mean dif­fer­enc­es (Mdiff) for ­each of: MVC, ISO (­peak ­torque), and EMG for ­upper rec­tus (UR), low­er rec­tus (LR), inter­nal ­oblique (IO), and exter­nal ­oblique (EO). A T-Test was ­used to ­detect sig­nif­i­cance for the ­body fat meas­ures.
Results. Mean dif­fer­enc­es (Mdiff) ­were nor­mal­ly dis­trib­ut­ed ­about ­zero for ­both MVC and ISO (MVC= -0.55, ISO=4.57). The anal­y­sis by ­group ­showed no dif­fer­ence (p=0.596) on the report­ed ­means (Nm) -3.16 (C), 5.84 (F) and -4.83 (R). The ­change asso­ciat­ed to the treat­ment dur­ing MVC was ­only 4% (η=0.04). For the ISO the Mdiff (Nm) ­were 1.39 (C), 13.66 (F) and -2.06 (R) ­which ­were not sig­nif­i­cant (p=0.127). The Ab-Flex was the ­only ­group to ­have a 95% con­fi­dence inter­val ­above ­zero, increas­ing by an aver­age of 16.5%. There ­were no sig­nif­i­cant dif­fer­enc­es for the EMG activ­ity for Mdiff or ­between ­group ­scores.
Conclusions. No sig­nif­i­cant dif­fer­enc­es ­were ­found ­with ­this ­study. These ­results ­would sug­gest ­that ­using ­these devic­es ­does not add sig­nif­i­cant­ly to over­all abdom­i­nal ­strength devel­op­ment, or reduc­tion of ­body fat. A sug­ges­tion ­could be ­made ­that cer­tain devic­es influ­ence mus­cles dif­fer­ent­ly.

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