Duke Economics

Recent Publications

• • TJ Somers, JA Blumenthal, F Guilak, VB Kraus, DO Schmitt, MA Babyak, LW Craighead, DS Caldwell, JR Rice, DC McKee, RA Shelby, LC Campbell, JJ Pells, EL Sims, R Queen, JW Carson, M Connelly, KE Dixon, LJ Lacaille, JL Huebner, WJ Rejeski, FJ Keefe.
  • 2012.
  • Pain coping skills training and lifestyle behavioral weight management in patients with knee osteoarthritis: a randomized controlled study..
  • Pain
  • 153:
  • 1199-209
  • .

  Publication Description

  Overweight and obese patients with osteoarthritis (OA) experience more OA pain and disability than patients who are not overweight. This study examined the long-term efficacy of a combined pain coping skills training (PCST) and lifestyle behavioral weight management (BWM) intervention in overweight and obese OA patients. Patients (n=232) were randomized to a 6-month program of: 1) PCST+BWM; 2) PCST-only; 3) BWM-only; or 4) standard care control. Assessments of pain, physical disability (Arthritis Impact Measurement Scales [AIMS] physical disability, stiffness, activity, and gait), psychological disability (AIMS psychological disability, pain catastrophizing, arthritis self-efficacy, weight self-efficacy), and body weight were collected at 4 time points (pretreatment, posttreatment, and 6 months and 12 months after the completion of treatment). Patients randomized to PCST+BWM demonstrated significantly better treatment outcomes (average of all 3 posttreatment values) in terms of pain, physical disability, stiffness, activity, weight self-efficacy, and weight when compared to the other 3 conditions (Ps

• • MC O'Neill, D Schmitt.
  • 2012.
  • The gaits of primates: center of mass mechanics in walking, cantering and galloping ring-tailed lemurs, Lemur catta..
  • The Journal of experimental biology
  • 215:
  • 1728-39
  • .

  Publication Description

  Most primates, including lemurs, have a broad range of locomotor capabilities, yet much of the time, they walk at slow speeds and amble, canter or gallop at intermediate and fast speeds. Although numerous studies have investigated limb function during primate quadrupedalism, how the center of mass (COM) moves is not well understood. Here, we examined COM energy, work and power during walking, cantering and galloping in ring-tailed lemurs, Lemur catta (N=5), over a broad speed range (0.43-2.91 m s(-1)). COM energy recoveries were substantial during walking (35-71%) but lower during canters and gallops (10-51%). COM work, power and collisional losses increased with speed. The positive COM works were 0.625 J kg(-1) m(-1) for walks and 1.661 J kg(-1) m(-1) for canters and gallops, which are in the middle range of published values for terrestrial animals. Although some discontinuities in COM mechanics were evident between walking and cantering, there was no apparent analog to the trot-gallop transition across the intermediate and fast speed range (dimensionless v>0.75, Fr>0.5). A phenomenological model of a lemur cantering and trotting at the same speed shows that canters ensure continuous contact of the body with the substrate while reducing peak vertical COM forces, COM stiffness and COM collisions. We suggest that cantering, rather than trotting, at intermediate speeds may be tied to the arboreal origins of the Order Primates. These data allow us to better understand the mechanics of primate gaits and shed new light on primate locomotor evolution.

• • C. Workman and D.Schmitt.
  • 2012.
  • Positional behavior of Delacour’s langurs (Trachypithecus delacouri) in northern Vietnam.
  • International Journal of primatology
  • 33:
  • 19 - 37
  • .
• • D. Schmitt.
  • 2012.
  • Primate Locomotor Evolution: Biomechanical Studies of Primate Locomotion and Their Implications for Understanding Primate Neuroethology.
  • 31-61
  • .
• • KD Allen, BA Mata, MA Gabr, JL Huebner, SB Adams Jr, VB Kraus, DO Schmitt, LA Setton.
  • 2012.
  • Kinematic and dynamic gait compensations resulting from knee instability in a rat model of osteoarthritis..
  • Arthritis research & therapy
  • 14:
  • R78
  • .

  Publication Description

  BACKGROUND: Osteoarthritis (OA) results in pain and disability; however, preclinical OA models often focus on joint-level changes. Gait analysis is one method used to evaluate both preclinical OA models and OA patients. The objective of this study is to describe spatiotemporal and ground reaction force changes in a rat medial meniscus transection (MMT) model of knee OA and to compare these gait measures with assays of weight bearing and tactile allodynia. METHODS: Sixteen rats were used in the study. The medial collateral ligament (MCL) was transected in twelve Lewis rats (male, 200 to 250 g); in six rats, the medial meniscus was transected, and the remaining six rats served as sham controls. The remaining four rats served as naïve controls. Gait, weight-bearing as measured by an incapacitance meter, and tactile allodynia were assessed on postoperative days 9 to 24. On day 28, knee joints were collected for histology. Cytokine concentrations in the serum were assessed with a 10-plex cytokine panel. RESULTS: Weight bearing was not affected by sham or MMT surgery; however, the MMT group had decreased mechanical paw-withdrawal thresholds in the operated limb relative to the contralateral limb (P = 0.017). The gait of the MMT group became increasingly asymmetric from postoperative days 9 to 24 (P = 0.020); moreover, MMT animals tended to spend more time on their contralateral limb than their operated limb while walking (P