ARENDSE, R. E., T. D. NOAKES, L. B. AZEVEDO, N. ROMANOV, M. P. SCHWELLNUS, and G. FLETCHER. Reduced Eccentric Loading of the Knee with the Pose Running Method. Med. Sci. Sports Exerc., Vol. 36, No. 2, pp. 272-277, 2004.
Purpose: The aim of this study was to compare the biomechanical changes during natural heel-toe running with learned midfoot and Pose running.
Methods: Twenty heel-toe runners were instructed in midfoot running and a novel running style in which the acromium, greater trochanter, and lateral malleolus are aligned in stance (Pose running). Clinical gait analysis was performed for each running style and the biomechanical variables compared.
Results: In comparison with midfoot and heel-toe running Pose running was characterized by shorter stride lengths and smaller vertical oscillations of the sacrum and left heel marker. Compared with midfoot and Pose running heel-toe running was characterized by greater magnitudes and loading rates of the vertical impact force. In preparation for initial contact, the knee flexed more in Pose than in heel-toe and midfoot running. The ankle at initial contact was neutral in Pose compared with a dorsiflexed and plantarflexed position in heel-toe and midfoot running, respectively. The knee power absorption and eccentric work were significant lower (P < 0.05) in Pose than in either heel-toe or midfoot running. In contrast, there was a higher power absorption and eccentric work at the ankle in Pose compared with heel-toe and midfoot running.
Conclusions: Pose running was associated with shorter stride lengths, smaller vertical oscillations of the sacrum and left heel markers, a neutral ankle joint at initial contact, and lower eccentric work and power absorption at the knee than occurred in either midfoot or heel-toe running. The possibility that such gait differences could be associated with different types and frequencies of running injuries should be evaluated in controlled clinical trails.
Running style is described as a learned response to a given set of anthropometric and physiological constraints (4) so that the movement of the body components minimizes the amount of mechanical work performed (1). Running style may be described by the overall action, body angle, arm swing, foot placement, rear leg lift, and length of stride (19).
The biomechanical variables associated with specific running styles change with running speed (16), inclination of the running surface (2,20), the use of running shoes (6), and the use of treadmills (24). Biomechanical variables also differ between different running styles for example between forward and backward running (7).
Backward running is characterized by initial contact with the midfoot, with the ankle plantarflexed (7). Compared with forward running, the knee is more flexed in terminal swing, initial contact, and stance (7). One of the consequences of this running style is that the peak ground reaction force is only 25-33% of that measured during forward running, suggesting that the calf musculature absorbs more of the impact forces during backward running (15). The peak patellofemoral compressive force is also reduced with backward running (3.0 ± 0.6 body weight (BW) compared with 5.6 ± 1.3 BW for forward running (8)). These biomechanical characteristics of backward running may be more beneficial in the treatment of running injuries, as suggested by anecdotal reports (15). But backward running is an impractical method for the treatment or prevention of running injuries.
Running in the forward direction with similar flexed knee geometry and midfoot contact to that of backward running may be hypothesized to offer equivalent treatment benefits. Midfoot running is, however, not associated with a lower risk of injury (3). Although the stance phase knee geometry of midfoot running is not described, it appears that foot contact is unlikely to be the exclusive determinant of the risk of injury.
A novel running style with a midfoot strike pattern and a flexed knee in stance has been developed and is called Pose running. The Pose running lower-limb geometry instance is achieved by forward lean of the trunk and vertical alignment of the ipsilateral shoulder, hip, and heel of the supporting limb. Pose running therefore appears to have a similar lower-limb geometry to backward running. It is intuitive that Pose running may have a role in the treatment of running injuries equivalent to backward running.
Accordingly, the aims of this study were to determine whether clinical gait analysis can distinguish between midfoot and Pose running in natural heel-toe recreational runners and whether the Pose method produces biomechanical changes that might be of value in the treatment or prevention of running injuries.