The evidence base for diaphragmatic breathing (DB) as an adjunctive treatment modality for persons with COPD is questionable. This article reviews the literature regarding the efficacy of DB in persons with chronic obstructive pulmonary disease (COPD), and reports on the beneficial and detrimental effects of DB in persons with COPD. Diaphragmatic breathing has been described as breathing predominantly with the diaphragm while minimizing the action of accessory muscles that may assist with inspiration. No single or combined patient characteristic has been identified consistently to help predict which person with COPD may benefit from DB. However, it has been suggested that persons with moderate to severe COPD and marked hyperinflation of the lungs without adequate diaphragmatic movement and increase in tidal volume during DB may be poor candidates for instruction in DB. Conversely, persons with COPD who have elevated respiratory rates, low tidal volumes that increase during DB, and abnormal arterial blood gases with adequate diaphragmatic movement may benefit from DB. Identification of an abdominal paradoxical breathing pattern and worsening dyspnea and fatigue during or after DB are criteria to modify or terminate DB. Persons with COPD demonstrating an abdominal paradox during DB may benefit from a more upright body position or trunk flexion. Several methods to examine diaphragmatic movement and the potential for success with DB will be discussed. Future research is needed to better identify which patients may benefit from DB.

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Coordination between the left and right limbs during cyclic movements, which can be characterized by the amplitude of each limb's oscillatory movement and relative phase, is impaired in patients with Parkinson's disease (PD). A pedaling exercise on an ergometer in a recent clinical study revealed several types of coordination disorder in PD patients. These include an irregular and burst-like amplitude modulation with intermittent changes in its relative phase, a typical sign of chaotic behavior in nonlinear dynamical systems. This clinical observation leads us to hypothesize that emergence of the rhythmic motor behaviors might be concerned with nonlinearity of an underlying dynamical system. In order to gain insight into this hypothesis, we consider a simple hard-wired central pattern generator model consisting of two identical oscillators connected by reciprocal inhibition. In the model, each oscillator acts as a neural half-center controlling movement of a single limb, either left or right, and receives a control input modeling a flow of descending signals from higher motor centers. When these two control inputs are tonic-constant and identical, the model has left-right symmetry and basically exhibits ordered coordination with an alternating periodic oscillation. We show that, depending on the intensities of these two control inputs and on the difference between them that introduces asymmetry into the model, the model can reproduce several behaviors observed in the clinical study. Bifurcation analysis of the model clarifies two possible mechanisms for the generation of disordered coordination in the model: one is the spontaneous symmetry-breaking bifurcation in the model with the left-right symmetry. The other is related to the degree of asymmetry reflecting the difference between the two control inputs. Finally, clinical implications by the model's dynamics are briefly discussed.

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These results indicated that patients with Parkinson's disease overestimated their stability limits, which may result in falls. In addition, the results demonstrate that patients with Parkinson's disease develop overestimation of stability limits in parallel with their disease progression.

We measured oxygen consumption in the exercising lower limb by using noninvasive tissue oximetry with the near-infrared spectra of hemoglobin in the quadriceps muscle during bicycle ergometer exercise in four normal controls and three patients with chronic progressive external ophthalmoplegia (CPEO) as well as one patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS). Normal controls showed constant oxygenation during exercise and a rapid recovery after exercise. However, all four patients with mitochondrial myopathy showed abnormal oxygenation during exercise and a slow recovery afterward. The results reflected the defect in oxidative phosphorylation and the impairment in oxygen utilization in those patients. The distinctive patterns of imbalance between oxygen delivery and utilization correlated well with the severity of mitochondrial myopathy as judged by the sum of the serum lactate and pyruvate content during exercise. Noninvasive tissue oximetry may be useful to measure the severity of myopathy and exercise intolerance in patients with mitochondrial myopathy.

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