Exercise Physiology Monitoring and Modeling

Motivation

Running is a great exercise that can be incorporated into any training regime and can be done by people of various ages with widely differing levels of fitness. Running has many physiological benefits including potential weight loss, improved cardiovascular health, increased muscle mass and increased bone density. However, due to its high-impact nature, there are many injuries associated with running. Common injuries include knee pain, shin splints, pulled muscles, twisted ankles, iliotibial band syndrome, plantar fasciitis, and Achilles tendinitis. While some of the injuries are caused by over-exertion, running form also contributes towards a majority of the cases. In a survey by the American Orthopaedic Foot and Ankle Society, 63% of respondents reported having an injury related to their shoes. According to the American Academy of Orthopaedic Surgeons, more than 43.1 million Americans--one in every six persons--have trouble with their feet, mostly from improperly-fitting shoes. A huge public health risk, foot problems cost the U.S. $3.5 billion a year. A majority of these problems can be addressed by improving the running efficiency.

Foot Pronation

Biomechanical efficiency is one of the most important contributory factors for injury prevention and enhancing performance. In particular, the angle of the foot when it hits the ground can significantly affect efficiency. This angle is broadly defined as pronation. Runners can be usually classified into one of three broad pronation categories: neutral, overpronation, and supination (underpronation). Overpronation is the excessive inward roll of the foot after landing. In overpronators, the foot continues to roll when it should be pushing off. This twists the foot, shin and knee and can cause pain in all those areas. Supination is caused by insufficient inward roll of the foot after landing. This places extra stress on the foot and can result in iliotibial band syndrome of the knee, achilles tendinitis, plantar fasciitis. Properly identified, pronation can usually be corrected with proper shoe selection or using sole inserts.

AOP
This figure shows the different types of pronation. The angle of pronation (AOP) is also defined.

Pronation Detection System

We are currently developing a system for detecting pronation using the Intel Wireless Identification and Sensing Platform (WISP). This system uses specialized RFID tags that are able to sense 3d acceleration without the need of a power supply. These tags are attached to the side of the leg and can sense the motions as a runner moves through a stride. By collecting data from runners who pronate with differing severity, we can build a pronation classifier based on histrogram matching. Runners to be classified run on the treadmill for a short period of time. During this time, a distribution is made of the lateral leg accelerations observed. This distribution is then compared to other known distributions.

AOP
The long sensor at the bottom is a WISP sensor. Other common motes are included for scale.

System Video


Publications

Erickson09b
Varick Erickson, Ankur U. Kamthe, Alberto E. Cerpa, "Demo Abstract: Measuring Foot Pronation Using RFID Sensor Networks," To appear in the Proceedings of the 7th ACM conference on Embedded Network Sensor Systems (SenSys 2009), ACM, Berkeley, CA, USA, November, 2009.

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