Mechanical determinants of walking energetics in older adults (Felperin, Ortega). Muscles must perform at least four functions during walking: (1) Generate muscular force to support body weight; (2) Perform mechanical work to redirect and restore the center of mass velocity during the step-to-step transition; (3) Swing the legs; and (4) Maintain stability. We are performing a series of experiments that manipulate one or more of these functions so as to quantify the cost of each function in normal healthy older adults.

Mechanics and Energetics of Walking in Curved Soled Shoes (Anecito, Ortega). It has been suggested that walking in curved bottom shoes has become a popular among fitness enthusiasts. However, little is known about the effects of using curved shoes on the metabolic cost and mechanics of walking. This study investigates the effects of walking in curved shoes on the metabolic cost, inverted pendulum mechanics and mechanical work associated with walking at different speeds.

Effect of mild traumatic brain Injury (mTBI/concussion) on neurocognitive function and motor control (Garcia, LaFarga, Larson, Ortega). Individuals who experience a mTBI are known to exhibit decreases in brain function and motor control. We are performing a series of studies that look at the relationships between neurocognitive function, balance and walking mechanics and how these factors change during concussion recovery.

Effects of age and physical activity on mobility, balance and fall risk in rural and urban dwelling older adults (Alvarado, LaFarga, Ortega). Normal aging is associated with impaired mobility, reduced balance and an increased risk of falls. This series of studies look at how living in rural vs. urban communities influences balance, mobility and fall risk and how different types of exercise may be used to improve balance and mobility and reduce fall risk in older adults.

Effects of immersion physical therapy on balance and mobility in knee osteoarthritis patients (Alvarado, Ortega). Knee osteoarthritis is associated with slower preferred walking speed, increase pain during walking and standing and reduced balance. Recently, water immersion physical therapy has been used in the physical rehabilitation process for these patients. The purpose of this study was to determine the relative effect of immersion therapy and lab-based therapy on balance and mobility in knee osteoarthritis patients.

Effect of mass distribution on energetics and mechanics of walking (Mannatt, Ortega). It has been shown that adding as little as 4 kg of load to the feet substantially increases the energetic cost of walking while adding as much as 20% BW load on top of the head doe not increased energetic cost. The purpose of this study is to determine how distributing a load on the body (feet, hip, shoulder or head) influences the metabolic cost and mechanics of walking.

Opportunities for Undergraduates
• The requirements for undergraduate students who want a research experience in our Laboratory are:
o Completed at least one year in college.
o Will be at Humboldt for at least two more semesters.
o Available for 5-10 hours of time per week in blocks of 2-4 hours at a time.
o Kinesiology majors are encouraged.
• For more information, contact Sarah Landis (sam85@humboldt.edu). Unfortunately, due to high demand, we cannot accommodate all qualified students.

Recent Publications
• Venturelli, M and Ortega JD (2013). Skeletal muscle mechanical efficiency does/does not change with age. Journal of Applied Physiology, 114(8):1108-1109.

• Kontos AP and Ortega JD (2011). Neuromotor effects of concussion: A biobehavioral model (p.325-356). In Handbook of Sport Neuropsychology (1st Ed). New York, NY. Springer Publishing.

• Nelson  FE, Ortega JD, Jubrias  S, Kushmerick MJ, and Conley  KE. (2011) A Review: High efficiency in human muscle: an anomaly and an opportunity? Journal of Experimental Biology 214, 2649-2653.

• Frey DJ, Ortega JD, Wiseman C, Farley CT, Wright KP. (2010) Influence of zolpidem and sleep inertia on balance and cognition during nighttime awakening: a randomized placebo-controlled trial. Journal of the American Geriatric Society 59(1):73-81

• Ortega, JD and Farley, CF. (2008) Energetic cost of stability and arm swing in young and elderly adults. Journal of Biomechanics 41(16): 3303-8.