The Role of Objective Movement Analysis in the Control of Yoga Asanas: A Case Study.

INTRODUCTION: Yoga is classified as a form of complementary and alternative medicine. It can be used in many disciplines including physiotherapy, medicine, and sport. The objective of the study was to identify possible biomechanical problems during yoga practice and to minimize the risk of injury. CASE PRESENTATION: Objective evaluation of the symmetry of asanas, balance, stability, and muscle tension was provided in case of a 37-year-old woman, practicing mainly aerial and Hatha yoga for 6 years. The bigger body tilt and deviations in center of pressure (COP) parameters were observed in tadasana during forward examinations. In tadasana, the highest muscle activity was observed in the rectus femoris. In case of forward tadasana observation, the highest activity was found in the gastrocnemius and in the lumbar portion of the erector spinae. During backward tadasana trial, the most active were the tibialis anterior and rectus femoris muscles. In garudasana and natarajasana, the symmetry of the trunk position in relation to the lower limbs was observed, regardless of the supporting limb. In the same way, COP parameters in garudasana were similar regardless of the supporting limb. However, in natarajasana, the higher COP displacement parameters were observed in the case of the nondominant supporting limb. As for the electromyographic evaluation of garudasana and natarajasana, the highest muscle activity was observed in the lumbar portion of the erector spinae. In chakrasana, a slightly greater angle of the hip extension was observed in the left hip. A higher muscle activity in chakrasana was observed in the lumbar portion of the right erector spinae. In sirsasana, no significant displacements of the cervical spine were observed, but a higher activity of the left sternocleidomastoid muscle was found. CONCLUSION: With the use of objective movement analysis, possible biomechanical problems were identified. Attention should be paid to the normalization of the tension in the lumbar part of the right erector spinae and the right sternocleidomastoid muscle, as well as to the balance training in positions on the nondominant lower limb. Objective movement analysis can be a useful tool for instructors or physiotherapists to adjust yoga programs and correct asanas in order to avoid future injuries.Yoga gilt als Form der Komplementär- und Alternativmedizin. Es ist in vielen Disziplinen einsetzbar, von Physiotherapie über Medizin bis Sport. Das Ziel dieser Studie war es, mögliche biomechanische Probleme bei der Ausübung von Yoga zu identifizieren, um das Verletzungsrisiko zu minimieren.Eine objektive Beurteilung der Symmetrie der Asanas, des Gleichgewichts, der Stabilität und der Muskelspannung erfolgte bei einer 37-jährigen Frau, die seit 6 Jahren hauptsächlich Aerial- und Hatha-Yoga praktiziert. Stärkere Körperneigung und Abweichungen bei Druckmittelpunkt-Parametern wurden in Tadasana bei der Vorwärts-Beobachtung festgestellt. In Tadasana wurde die höchste Muskelaktivität im Rectus femoris beobachtet. Bei der Tadasana-Vorwärts-Beobachtung war die höchste Aktivität im Gastrocnemius und im lumbalen Anteil des Erector spinae zu verzeichnen. Während der Tadasana-Rückwärts-Übung waren die aktivsten Muskeln der Tibialis anterior und Rectus femoris. In Garudasana und Natarajasana wurde die Symmetrie der Rumpfposition im Verhältnis zu den unteren Gliedmaßen unabhängig von der belasteten Gliedmaße beobachtet. Ebenso waren die Parameter des Druckmittelpunkts (DMP) in Garudasana unabhängig von der belasteten Gliedmaße vergleichbar. In Natarajasana wurden jedoch höhere Parameter der DMP-Verschiebung bei der nicht-dominanten belasteten Gliedmaße beobachtet. Bei der elektromyografischen Auswertung von Garudasana und Natarajasana wurde die höchste Muskelaktivität im lumbalen Anteil des Erector spinae beobachtet. In Chakrasana wurde ein etwas größerer Winkel der Hüftstreckung im linken Hüftgelenk beobachtet. Eine höhere Muskelaktivität in Chakrasana wurde im lumbalen Anteil des rechten Erector spinae beobachtet. In Sirsasana wurden keine signifikanten Verschiebungen der Halswirbelsäule beobachtet, jedoch war eine höhere Aktivität des linken Sternocleidomastoideus zu verzeichnen.Mit Hilfe einer objektiven Bewegungsanalyse wurden mögliche biomechanische Probleme identifiziert. Mit besonderer Aufmerksamkeit sollte auf die Normalisierung der Spannung im lumbalen Anteil des rechten Erector spinae und des rechten Sternocleidomastoideus sowie auf die Schulung des Gleichgewichts in Positionen auf der nicht-dominanten unteren Extremität geachtet werden. Die objektive Bewegungsanalyse kann ein nützliches Instrument für Instruktoren oder Physiotherapeuten sein, um Yoga-Programme anzupassen und Asanas zu korrigieren, um Verletzungen vorzubeugen.

The First Step in Standardizing an Artificial Aging Protocol for Dental Composites-Evaluation of Basic Protocols.

The clinical performance of a dental restoration is strongly influenced by the complex and dynamically-changing oral environment; however, no standard procedure exists to evaluate this lifetime. This research provides an in-depth analysis of the effect of different aging procedures on the flexural strength (FS), diametral tensile strength (DTS) and hardness (HV) of selected dental materials (Resin F, Flow-Art and Arkon). Material structure was evaluated by scanning electron microscopy. It was found that each aging protocol had some influence on the tested properties, with continual erosion and degradation being observed. Greater mechanical degradation was observed for Resin F (neat resin) after the applied aging protocols, suggesting that a resin matrix is more susceptible for degradation. The most aggressive aging protocol was Protocol 5: 0.1 M NaOH, seven days, 60 °C. Further studies on the effect of artificial aging on dental materials should include a study of the thermal and chemical factors. A standardized aging procedure is crucial for improving the resistance of dental resin composite to oral conditions and their clinical performance.

The Influence of Low-Molecular-Weight Monomers (TEGDMA, HDDMA, HEMA) on the Properties of Selected Matrices and Composites Based on Bis-GMA and UDMA.

Bisphenol A-glycidyl methacrylate (bis-GMA) and urethane dimethacrylate (UDMA) are usually combined with low-viscosity monomers to obtain more desirable viscosity, handling characteristics and general properties. The present study determined the flexural strength (FS), flexural modulus (FM), diametral tensile strength (DTS), and hardness (HV) of five matrices and composites based on these resins. The polymerization shrinkage stress (PSS) was also studied for the composites. The polymer matrices were formed using bis-GMA and UDMA. TEGDMA, HEMA and HDDMA acted as co-monomers. The composites had 45 wt.% of filler content. The highest FS and FM were obtained from the UDMA/bis-GMA/TEGDMA/HEMA matrix and the composite (matrix + filler). The best DTS values were obtained from the UDMA/bis-GMA/HEMA matrix and the composite. One of the lowest values of FS, FM, and DTS was obtained from the UDMA/bis-GMA/HDDMA matrix and the composite. All the composites demonstrated similar hardness values. The lowest polymerization shrinkage stress was observed for the UDMA/bis-GMA/TEGDMA/HEMA composite, and the highest PSS was observed for the UDMA/bis-GMA/TEGDMA/HDDMA composite. The addition of HEMA had a positive effect on the properties of the tested materials, which may be related to the improved mobility of the bis-GMA and UDMA monomers.