Nordic walking (NW) was compared with walking (W) and running (R) with respect to upper and lower limb injury risks. 24 NW-instructors performed W, NW, and R trials on a runway covered with artificial turf at controlled speeds. Foot pronation and ground reaction forces were measured as well as shock wave transmission to the right wrist. Comparison of NW and W shows similar results for all of the four chosen velocities (5 km/h, 7 km/h, 8 km/h, 8.5 km/h). Except for the 2nd peak of the vertical ground reaction force, NW results in higher loading rates and horizontal forces as well as higher pronation and pronation velocity values as compared with W. Wrist acceleration values up to 7.6 times gravitational acceleration were recorded in NW. Compared with R at the same speeds (8 km/h and 8.5 km/h), NW can be recommended as low impact sport with 36% lower loading rates and 59% lower pronation velocities. However, the high wrist accelerations in NW reveal that the upper extremities are exposed to considerable repetitive shocks, which may cause overuse injuries of the upper extremities. Thus, additional preventive exercises for the upper limb muscles are recommended as well as using shock absorbing walking poles.
Marco Hagen, Ewald M. Hennig, and Peter Stieldorf
Ewald M. Hennig and Mario A. Lafortune
Using data from six male subjects, this study compared ground reaction force and tibial acceleration parameters for running. A bone-mounted triaxial accelerometer and a force platform were employed for data collection. Low peak values were found for the axial acceleration, and a time shift toward the occurrence of the first peak in the vertical force data was present. The time to peak axial acceleration differed significantly from the time to the first force peak, and the peak values of force and acceleration demonstrated only a moderate correlation. However, a high negative correlation was found for the comparison of the peak axial acceleration with the time to peak vertical force. Employing a multiple regression analysis, the peak tibial acceleration could be well estimated using vertical force loading rate and peak horizontal ground reaction force as predictors.
Ewald M. Hennig and Thomas L. Milani
Discrete pressure sensors were used to examine the influence of shoe construction on the local forces under the foot. Measurements were performed at eight locations under the feet of 22 subjects wearing 19 different models of running shoes. Mechanical properties of shoe soles were assessed with an impacter device. Pressure distribution, ground reaction force, and acceleration data were collected simultaneously during running at 3.3 m/s. Early lateral loading of the rearfoot was followed by increasing medial forefoot loads. In the later phase of pushoff the load was almost entirely carried by the first metatarsal head and the hallux. Substantial differences in plantar foot pressures and relative loads among shoe models indicated that footwear construction has a substantial influence on the loading behavior of the foot during ground contact. Finally, the chosen sensor locations under the foot were found to be adequate to estimate the vertical ground reaction force.
Ewald M. Hennig and David J. Sanderson
Foot function and possible mechanisms for the etiology of frequently observed forefoot complaints in bicycling were studied. Pedal forces and in-shoe pressure distributions were measured with 29 subjects, who rode on a stationary bicycle with a cadence of 80 rpm at 100, 200, 300, and 400 W. The influence of footwear on foot loading was also investigated by comparing running and bicycling shoes at 400 W. The first metatarsal head and the hallux were identified as the major force-contributing structures of the foot. High pressures under the toes, midfoot, and under the heel showed that all foot areas contribute substantially to the generation of pedal forces. For increasing power outputs, higher peak pressures and relative loads under the medial forefoot were identified. These may cause pressure-related forefoot complaints and accompany increased foot pronation. As compared to the running shoe, the stiff bicycling shoe demonstrated a more evenly distributed load across the whole foot and showed a significantly increased index of effectiveness.
Ewald M. Hennig, Thomas L. Milani, and Mario A. Lafortune
Ground reaction force data and tibial accelerations from a skin-mounted transducer were collected during rearfoot running at 3.3 m/s across a force platform. Five repetitive trials from 27 subjects in each of 19 different footwear conditions were evaluated. Ground reaction force as well as tibial acceleration parameters were found to be useful for the evaluation of the cushioning properties of different athletic footwear. The good prediction of tibial accelerations by the maximum vertical force rate toward the initial force peak (r 2 = .95) suggests that the use of a force platform is sufficient for the estimation of shock-absorbing properties of sport shoes. If an even higher prediction accuracy is required a regression equation with two variables (maximum force rate, median power frequency) may be used (r 2 = .97). To evaluate the influence of footwear on the shock traveling through the body, a good prediction of peak tibial accelerations can be achieved from force platform measurements.
Thomas L. Milani, Gerrit Schnabel, and Ewald M. Hennig
The purpose of this study was to investigate the influence of 8° varus and vaigus shoe modifications on the foot mechanics in overground running. Twenty male subjects performed eight rearfoot running trials in three shoe conditions. Ground reaction forces, tibial accelerations, rearfoot motion, and in-shoe pressure distribution data were collected simultaneously. Between footwear conditions, force and acceleration parameters were found to be significantly different. Compared to the neutral shoe, maximum pronation and pronation velocity were reduced for the varus and increased for the vaigus shoes. Higher lateral rearfoot loads and an increased contribution of the first ray in the forefoot could be evaluated for the vaigus shoe. In contrast, a larger contribution of the medial midfoot and the fifth metatarsal head was observed for the varus shoe. The relative load analysis from the pressure distribution measurements provided additional information about the behavior of the foot in response to major changes in shoe construction.
Ewald M. Hennig, Gordon A. Valiant, and Qi Liu
Using a 15-point rating scale, subjects rated perception of cushioning during running on a treadmill with three different footwear constructions of varying midsole hardness. During overground running, various biomechanical ground reaction force and pressure variables were collected and compared to the perception of cushioning scores. The perception scores identified the three shoes as very hard, medium soft, and soft. Peak pressures in the heel, the force rate, and the median power frequency of the impact force signal demonstrated increases in values with the perception of less cushioning. In the harder shoes, the subjects altered the loading patterns under their feet, resulting in lower impact forces and increased weight bearing of the forefoot structures.
Peter R. Cavanagh, Gary C. Andrew, Rodger Kram, Mary M. Rodgers, David J. Sanderson, and Ewald M. Hennig
A comprehensive biomechanical profile for the evaluation of elite distance runners is outlined. The profile includes the following sections: (a) structural assessment, (b) movement analysis, (c) plantar force and pressure, and (d) selected metabolic measurements. For each of these sections the methodology is described, examples of results from two elite distance runners evaluated are presented and, where appropriate, recommendations for performance improvement and/or injury prevention are made. The concluding discussion addresses a number of philosophical issues related to the biomechanical study of elite athletes and makes some' recommendations for farther development of programs of this nature.