title: Low-Budget Instrumentation of a Conventional Leg Press to Measure Reliable Isometric-Strength Capacity.
abstract: Maximum strength and rate of force development (RFD) are 2 important strength characteristics for everyday tasks and athletic performance. Measurements of both parameters must be reliable. Expensive isokinetic devices with isometric modes are often used. The possibility of cost-effective measurements in a practical setting would facilitate quality control. The purpose of this study was to assess the reliability of measurements of maximum isometric strength (Fmax) and RFD on a conventional leg press. Sixteen subjects (23 ± 2 y, 1.68 ± 0.05 m, 59 ± 5 kg) were tested twice within 1 session. After warm-up, subjects performed 2 times 5 trials eliciting maximum voluntary isometric contractions on an instrumented leg press (1- and 2-legged randomized). Fmax (N) and RFD (N/s) were extracted from force-time curves. Reliability was determined for Fmax and RFD by calculating the intraclass correlation coefficient (ICC), the test-retest variability (TRV), and the bias and limits of agreement. Reliability measures revealed good to excellent ICCs of .80-.93. TRV showed mean differences between measurement sessions of 0.4-6.9%. The systematic error was low compared with the absolute mean values (Fmax 5-6%, RFD 1-4%). The implementation of a force transducer into a conventional leg press provides a viable procedure to assess Fmax and RFD. Both performance parameters can be assessed with good to excellent reliability allowing quality control of interventions.
authors.affiliation: Bern University of Applied Sciences, Health, Physiotherapy, Bern, Switzerland.
authors.forename: Heiner
authors.initials: H
authors.lastname: Baur
authors.forename: Alessia Severina
authors.initials: AS
authors.lastname: Groppa
authors.forename: Regula
authors.initials: R
authors.lastname: Limacher
authors.forename: Lorenz
authors.initials: L
authors.lastname: Radlinger
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005080:Exercise Test / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007866:Leg / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D015203:Reproducibility of Results; D019415:Torque; D055815:Young Adult
keywords: muscle strength; muscle strength dynamometer; resistance training