title: Kinetic comparison of free weight and machine power cleans.
abstract: The purpose of this investigation was to compare the kinetic characteristics of the power clean exercise using either free weight or machine resistance. After familiarization, 14 resistance trained men (mean +/- SD; age = 24.9 +/- 6.2 years) participated in two testing sessions. During the initial testing session, one-repetition maximum performance (1RM) was assessed in either the free weight or machine power clean from the midthigh. This was followed by kinetic assessment of either the free weight or the machine power clean at 85% of 1RM. One week after the initial testing session, 1RM performance, as well as the subsequent kinetic evaluation, were performed for the alternate exercise modality. All performance measures were obtained using a computer-interfaced FiTROdyne dynamometer (Fitronic; Bratislava, Slovakia). Maximum strength (1RM) and average power were significantly greater for the free weight condition, whereas peak velocity and average velocity were greater for the machine condition (p < 0.05). Although peak power was not different between modalities, force at peak power (free weights = 1445 +/- 266 N, machine = 1231 +/- 194 N) and velocity at peak power (free weights = 1.77 +/- 0.28 m x s(-1), machine = 2.20 +/- 0.24 m x s(-1)) were different (p < 0.05). It seems that mechanical limitations of the machine modality (i.e., lift trajectory) result in different load capacities that produce different kinetic characteristics for these two lifting modalities.
authors.affiliation: Human Performance Laboratories, The University of Memphis, Memphis, Tennessee, USA.
authors.forename: R Murry
authors.initials: RM
authors.lastname: Jones
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Fry
authors.forename: Lawrence W
authors.initials: LW
authors.lastname: Weiss
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kinzey
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Moore
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D053581:Muscle Strength Dynamometer; D055070:Resistance Training / Q000295:instrumentation* / Q000379:methods; D014891:Weight Lifting / Q000502:physiology*