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National Biomechanics Day (NBD) was initiated in 2016 as a nation-wide effort to introduce Biomechanics to high school students throughout the United States. After that initial year, many people around the world joined NBD to promote Biomechanics in their own countries. National Biomechanics Day became international. We describe NBD procedures and events in four of these countries with the intent of demonstrating mechanisms that may enable Biomechanists around the world to successfully join the NBD celebration.

peer-reviewed ???????????????????????????????????????????????????? The fixed position of force plates has led researchers to pursue alternative methods of determining centre of pressure (CoP) location. To date, errors reported using alternative methods to the force plate during dynamic tasks have been high. The aim of this study was to investigate the accuracy of a motion analysis marker-based system to determine CoP during a two-legged hopping task. Five markers were attached to the left and right feet of eight healthy adults (5 females, 3 males, age: 25.0??2.8 years, height: 1.75??0.07 m, mass: 71.3??11.3 kg). Multivariate forward stepwise and forced entry linear regression was used with data from five participants to determine CoP position during quiet standing and hopping at various frequencies. Maximum standard error of the estimate of CoP position was 12 mm in the anteroposterior direction and 8 mm in the mediolateral. Cross-validation was performed using the remaining 3 participants. Maximum root mean square difference between the force plate and marker method was 14 mm for mediolateral CoP and 20 mm for anteroposterior CoP during 1.5 Hz hopping. Differences reduced to a maximum of 7 mm (mediolateral) and 14 mm (anteroposterior) for the other frequencies. The smallest difference in calculated sagittal plane ankle moment and timing of maximum moment was during 3.0 Hz hopping, and largest at 1.5 Hz. Results indicate the marker-based method of determining CoP may be a suitable alternative to a force plate to determine CoP position during a two-legged hopping task at frequencies greater than 1.5 Hz. ACCEPTED peer-reviewed

World-class athletes of both sexes cover 100 metres in about 10 seconds. What percentage of this is spent not touching the ground? And what's the figure for a 2-hour marathon?