Closed kinetic chain (linear) isokinetic testing: Relationships to functional testing

Abslract . S/lidy (Ies/gll: A corrcJ;;llion slUdy 10 delcmline Ihe relati onship of the results of linear isokinctk Icsti ng and various fUllctionultest s. Objeclil·cs: To detennine the relation shi p of scores on a linear isokiuetic test 10 scores on a ' ·<lriCI), of lower extremity functional tests. Background: Both isokinetic testing aud functional tests arc commonly used during the rehabilitation of individual s wilh sports <l nd orthopedic injuries. Limited inforll1ation exists regarding the re1<1tionships of scores on a linear isokinetk lesl and scores on functionallesls. M ethods all(/ measures: Twenty-nine hC<ll1hy subjccts perfonned a n:locity spectrum linear isokinetic test consist in g of 3 sets in <I bilateral rec ipmc<ll Ill ode. followed by three scl~ in a bilateml coupled mode. Testing ,·elocities were 25A. 50.8 <lml 76.2 cm per se cond. Six Ill<l.\im<ll volitionul1inear isokinet ic repetitions were perfonlled at e:lch testing velocity. Following linear isokinetic testing. su bjects perfonned 5 funct ional tests: bi lateral leg ,·ertical jump. unilat eral leg venic:lI jump. double legjump for distance. si ngle.leg hop for distance. an d single.leg limed 6·meter hop. Functional testing ent:likd 3 lI1<1xilll<ll volitional attempts of the 5 procedures for both the dominant and non·dominant lower extremity. The me<ln of the 3 al1empl~ was used for c:llculmions. Memls and sl:ln d:lrd devimions of the func tion:!1 test scores :lnd isokinelic lesl scores were detemlined us in g sl:lndard st<lliSl ic<l1 procedures. PC<lTSon product moment cOTTei<Jtion cocfficiems were used to detemline the rel:ltiollsh ip between the mean scores onlhc linc<lr iso kinctic test scorcs <lnd funct ion<llteSls for both Ihe dominam ami non-dominant limbs. Re.\JI/ts: Twellly-Ih ree OUI of 36 cOTTel<llion cocfficielll!; were significan t at the p < 0.01 level. whi Ie 12 OUI of 36 were significant at the p < 0.05 lel'el. Only l out of 36 was non-significant when comparing bilateral rcci proc<ll scores 10 single.leg functional te, 1 scores. The bilater<ll reciproc<l l cOTTelation coefficients ranged from -0.36 to 0 .65. Six OUI of 12 bilmer.J1 coupled correlation coefficienlS were s ignificant at p < 0.0 1. while 3 out of 12 were signific:lnl al ~he JJ <: 0_05 1.,,·.,1 and only 3 were cO ll ,idered non -significant. The bilmeral coupled cOTTelation coefficicnts rang.,d from 0 .11 100.64. COllell/siolls: Re sults from this slU dy indica te :! signific:l 1II rel :ltionship exists belween the re sullS of linear iso kinetic !esti ng <lnd various function:lllesis. Despite the signific <llll rel <ltionshi p. Ihe m<ljorit)' of Pearson Product mome nt correl:ltion coefficienlS were in the low to moder<lte ra nge. Thcrefore. Ihe usc of either a line:lr isokinetic test or a functional test in isolat ion 10 detemline strength :llld perform:lnce is strongly discouraged. LinC<lr isokinelic testing should be used for testing lower e"trem ity slrength. while functi on<ll tests should be used to dete mline pc rfoml<lncc le,·els. The authors recoJllmend lIIilizing both testing m~thods since Slrengl h docs nOi <llwa)'$ cOTTelate strongly with ph)'sieal perfonnance.