Forefoot deformation during stance: does the forefoot collapse during loading?

This study presents a specific description of forefoot deformation during the stance phase of normal human walking based on the combined analysis of pressure and three-dimensional optoelectronic measurements. Forefoot deformation is measured in forty healthy subjects using (1) a six-camera motion capture system (sampled at 250 Hz) tracking five reflective skin markers attached to the forefoot, (2) a pressure platform (sampled at 500 Hz) and (3) a forceplate (sampled at 1250 Hz). Forefoot deformation is characterized by the forefoot width, the mediolateral metatarsal arch height and the plantar pressure under the metatarsal heads. Using this setup, a typical pattern of forefoot motion is described during stance phase: From a flexible, compliant configuration at the beginning of stance phase, characterized by a decrease in mediolateral metatarsal arch height and a controlled increase in forefoot width, the forefoot turns into a stable configuration during midstance. Subsequently, the increase in mediolateral arch height and the decrease in forefoot width describe the transformation into a tight configuration during final stance. This transfer from a compliant into a rigid configuration through stance phase rejects the idea of the forefoot as a collapsing structure under increased loading.

Influence of physical development on start and countermovement jump performance in adolescent sprint athletes.

AIM: The aim of the present study was to describe the effect of physical changes during adolescence on sprint start and countermovement jump (CMJ) performance. METHODS: Twenty-eight girls and 25 boys (15.0±1.6 and 14.7±1.9 years at start respectively) were measured twice with a one year interval. Anthropometric data allowed skeletal muscle mass (SMM) estimation. Athletes performed a 10m sprint tracked from behind by a laser sensor, with starting blocks measuring propulsion forces. CMJ's were performed on a Kistler force plate. RESULTS: Between the two measurement occasions both genders increased in body height, weight and SMM. In girls and boys, impulse during the push-off, block leaving velocity and times at 5 and 10 m improved significantly. In both genders CMJ absolute power increased but not power.kg-1. Only in boys a higher CMJ was registered on occasion 2. For both genders on both occasions, impulse during the push-off correlated with body weight, SMM and CMJ power (r from .46 to .84), and in boys also with CMJ height and CMJ power.kg-1 (r from 0.43 to 0.76). Boys showed CMJ height and power to correlate with 5 and 10 m times (r from -0.42 to -0.79) and with block leaving velocity, however only on the first data collection (r=0.61 and 0.59, respectively). CONCLUSION: Sprint start performance is only partly related to muscular development and CMJ could predict start performance in boys only. Sprint start and CMJ rely on technical skills and, therefore, increasing muscularity should be accompanied with sufficient specific training to allow an optimal transfer to start performance.

Anomalies of form and number, fused primary teeth, a correlation of the dentitions.

Fusion is rare in the primary dentition (range .14 percent to 3 percent). Patients with fused primary lateral incisors and canines have about a 75 percent chance of lacking the succedaneous lateral incisor. Patients with fused incisors have less than a 20 percent chance of having a missing permanent tooth.

Caries levels and patterns in head start children in fluoridated and non-fluoridated, urban and non-urban sites in Ohio, USA.

The purpose of the study was to determine caries levels and prevalences of previously identified caries patterns in low income children in the primary dentition in Ohio, USA. Children were examined from urban fluoridated (n = 505), urban non-fluoridated (n = 395), non-urban optimal fluoride (n = 183), and non-urban suboptimal fluoride (n = 227) sites. Caries scores were similar for the two sites having optimal fluoride; scores from fluoridated sites were lower than scores from the two suboptimal fluoride sites. Children from all four sites were caries-free ranging from 36% in the urban non-fluoridated site to 50% in the non-urban optimally fluoride site. More children in the suboptimal fluoridated sites had smooth surface lesions than in the optimally fluoridated sites. More children with defect associated lesions had fewer than six (chi 2 = 222; P less than 0.01) carious surfaces than did children with smooth surface lesions.

Fused primary teeth: a documented familial report of case.

A case report of fused teeth in two of five siblings is described. Both siblings had fusion of contralateral lower primary canines and lateral incisors. One had aplasia of one of the succedaneous lateral incisors.