As with any athlete, the dancer has a high risk for injury. Most studies carried out relate to classical and modern dance; however, there is a lack of reports on injuries involving other dance techniques. This study is an attempt to determine the differences in the incidence, the exposure-related rates, and the kind of injuries in three different dance techniques. A prospective study about dance injuries was carried out between 2004 and 2007 on students of modern, Mexican folkloric, and Spanish dance at the Escuela Nacional de Danza. A total of 1,168 injuries were registered in 444 students; the injury rate was 4 injuries/student for modern dance and 2 injuries/student for Mexican folkloric and Spanish dance. The rate per training hours was 4 for modern, 1.8 for Mexican folkloric, and 1.5 injuries/1,000 hr of training for Spanish dance. The lower extremity is the most frequent structure injured (70.47%), and overuse injuries comprised 29% of the total. The most frequent injuries were strain, sprain, back pain, and patellofemoral pain. This study has a consistent medical diagnosis of the injuries and is the first attempt in Mexico to compare the incidence of injuries in different dance techniques. To decrease the frequency of student injury, it is important to incorporate prevention programs into dance program curricula. More studies are necessary to define causes and mechanisms of injury, as well as an analysis of training methodology, to decrease the incidence of the muscle imbalances resulting in injury.

Zapateado is a repetitive percussive footwork in dance. This percussive movement, and the differences in technique, may be risk factors for injury. A survey on zapateado dance students found a rate of 1.5 injuries/1,000 exposures. Knee injuries are more frequent than in Spanish dancers than folkloric dancers. The aim of this research was to study the relationship between technique and ground reaction force between zapateado on Spanish and Mexican folkloric dancers. Ten female dance students (age 22.4 ± 4 yrs), six Spanish dancers and four Mexican folkloric dancers, were considered. Each student performed zapateado with a flat foot, wearing high-heeled shoes during 5 seconds on a force platform. Videotapes were taken on a lateral plane, and knee and hip angles in each movement phase were measured with Dartfish software. Additionally, knee and ankle flexor and extensor strength was measured with a dynamometer. Ground reaction forces were lower for Spanish dancers than Mexican folkloric dancers. Spanish dancers had less knee flexion when the foot contacted to the ground than did Mexican folkloric dancers. On Spanish dancers, the working leg had more motion in relation to hip and knee angles than was seen in folkloric dancers. The ankle extensors were stronger on folkloric dancers, and there were no differences for the other muscle groups. Knee flexion at foot contact and muscle strength imbalance could be risk factors for injuries. It is suggested that the technique in Spanish dance in Mexico be reviewed, although more studies are required to define more risk factors.

The effect of cholesterol incorporation on some functions of the mitochondrial inner membrane and on the morphology of rat liver mitochondria was studied. Basal ATPase and succinate dehydrogenase activities remained unchanged after cholesterol was incorporated into the mitochondria; however, uncoupled ATPase activity was partially inhibited. The presence of several substrates and inhibitors did not change the amount of cholesterol incorporated, which was localized mostly in the outer membrane. Electron-microscope observations revealed the presence of vesicles between the outer and inner membranes; these vesicles increased in number with the amount of cholesterol incorporated. The data suggest that cholesterol induces the formation of vesicles from the outer membrane, and modifies the activity of stimulated ATPase.

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