Degree of agreement between impulse and magnitude of momentum change for different types of movements

This study aims to investigate the degree of agreement between the impulse and the magnitude of momentum change (MMC) for various types of movements. Six males performed five successful trials for four movements: straight jogging (SJo), 90 degrees open cross cutting (OC), running jump for height (RJu), and curved jogging with a 5-m radius (CJo). Impulse and MMC were respectively measured using two forceplates and a 3D motion capture system with 10 infrared cameras. Correlation coefficients between the two were over 0.95 except for RJu's medio-lateral component (0.83). RJu motion is mainly in the sagittal plane, and it has a high-frequency impact force at touchdown; the accompanying noise explains the low correlation. In the vertical component, MMC increased with the impulse value. However, the relative error was similar to 10%. This is attributable to random equipment errors, error amplifications due to numerical calculations, and skin movements. (C) 2012 Elsevier B.V. All rights reserved.