Aerobic fitness and somatic growth in adolescents: a cross sectional investigation in a high school context.

AIM: A cross-sectional investigation to study the relations between aerobic fitness and somatic growth of Italian adolescents within a school context. METHODS: The Léger and Lambert 20-m shuttle run test scores were used to estimate the oxygen uptake (VO2max) of 290 high school adolescent students aged 14-18 years. Descriptive statistics of body mass, standing height, body mass index (BMI) and of predicted VO2max were calculated within age and sex group. RESULTS: Body mass and standing height were significantly larger in males than in females, and significantly increased with age (P < 0.002, analysis of variance). For standing height, a significant sex age interaction was found (P = 0.0004), with a larger age-related increment in males than in females. No significant differences in BMI were found. VO2max was significantly influenced by sex and age. The age-related decrement in VO2max was larger in females than in males (P = 0.001). Predicted VO2max was significantly related to BMI (males: r = -0.41; females: r = -0.336) and to body mass (females: r = -0.34; males: r = -0.352). A negative relationship between BMI and VO2max was found also in the overweight adolescents. CONCLUSIONS: In both sexes, aerobic fitness declined with age. The decline was particularly evident in females. Low-cost methods to detect the nutritional level and aerobic performance of adolescents should be encouraged at school.

The influence of occlusion on jaw and neck muscle activity: a surface EMG study in healthy young adults.

The electromyographic (EMG) characteristics of masseter, temporalis and sternocleidomastoid (SCM) muscles during maximum voluntary teeth clench were assessed in 27 male and 35 female healthy young adults. Subjects were divided into two groups: (i) 'complete' Angle Class I (bilateral, symmetric canine and molar Class I relationships), and (ii) 'partial' Angle Class I (one to three canine/molar Class I relationships, the remaining relationships were Class II or Class III). On average, standardized muscular symmetry ranged 80.7-87.9%. During maximum voluntary teeth clench, average co-contraction of SCM muscle was 13.7-23.5% of its maximum contraction. On average, all torque coefficients (potential lateral displacing component) were >90%, while all antero-posterior coefficients (relative activities of masseter and temporalis muscles) were >85%. The average integrated areas of the masseter and temporalis EMG potentials over time ranged 87.4-106.8 muV/muV s%. Standardized contractile muscular activities did not differ between 'complete' and 'partial' Angle Class I, and between sexes (two-way analysis of variance). A trend toward a larger intragroup variability in EMG indices was observed in the subjects with 'partial' Angle Class I than in those with 'complete' Angle Class I (significant difference for the temporalis muscle symmetry, P = 0.013, analysis of variance). In conclusion, the presence of a complete or partial Angle occlusal Class I did not seem to influence the standardized contractile activities of masseter, temporalis and SCM muscles during a maximum voluntary clench. Subjects with a 'complete' Angle Class I were somewhat a more homogenous group than subjects with 'partial' Angle Class I.

Spatiotemporal consistency of trajectories in gymnastics: a three-dimensional analysis of flic-flac.

Sport performance during the execution of closed skills combines specific body and limb movements into codified patterns where stability and consistency may be more important than variability. Repeated sport movements can be investigated to assess the consistency of body trajectories. More consistent trajectories will result in more repeatable movements. The present study quantified the short-term consistency of body trajectories during the performance of the backward flic-flac, a technique of floor gymnastics. Nine experienced gymnasts (six men, three women), all of national level, performed 10 repetitions of backward flic-flac. An optoelectronic instrument was used for the detection of the three-dimensional movement of 13 body landmarks. The spatiotemporal consistency of repeated landmark trajectories was measured by the standard deviation between standardized trajectories. The results showed smaller standard deviation (larger consistency between landmark trajectories) in female than in male gymnasts. The analysis of the consistency of landmark trajectories could help gymnasts indicating which parts of the body do not repeat a selected movement with sufficient accuracy.

Repeatability of choku-tsuki and oi-tsuki in shotokan karate: a 3-dimensional analysis with thirteen black-belt karateka.

13 black-belt karateka performed two different standardized counter-offensive techniques. The trajectories of selected body landmarks were studied by using a computerized image analyzer that allows a 3-dimensional reconstruction of standardized movements. The repeatability of both karate techniques was quantified for each participant. Analysis confirmed that more experienced karateka obtained the best repeatability, as already demonstrated in a preliminary study conducted with a smaller sample of less experienced participants.