This study compared actual and perceived physical competence of overweight and nonoverweight children. Participants were 109 nonoverweight and 33 overweight Grade 5 and 6 children (mean age 10.8 years). Overweight status was determined using age- and gender-specific international body-mass-index cut-off values. Actual competence was assessed using the Test of Gross Motor Development, 2nd ed., and perceived competence was assessed using an expanded version of the Athletic Competence subscale of the Self-Perception Profile for Children (SPPC). Overweight children had significantly lower actual and perceived physical competence. When actual competence was partitioned into locomotor and object-control skills, however, differences only existed for locomotor skills. These findings indicate that low actual and perceived physical competence might be important contributing factors in maintaining childhood obesity. Interventions to improve actual and perceived physical competence in overweight children should provide opportunities to learn and master fundamental movement skills in an environment where parents, teachers, and coaches provide positive and specific feedback, encouragement, and modeling.

OBJECTIVE: This study examines the relationship between obesity and foot structure in prepubescent children. DESIGN: Field-based, experimental data on BMI (body mass index) and foot structure were collected for 431 consenting children from 18 randomly selected primary schools. SUBJECTS: Of the 431 participants, 62 obese (BMI b 95th percentile) and 62 non-obese (10th percentile`BMI b 90th percentile) children (age 8.5 AE 0.5 y) were selected. MEASUREMENTS: Height and weight were measured to calculate BMI. Static weight-bearing footprints for the right and left foot of each subject were then taken using a pedograph to calculate the Footprint Angle and the ChippauxSmirak Index as representative measures of the surface area of the foot in contact with the ground. RESULTS: A signi®cant difference was found between the Footprint Angle of the obese and non-obese subjects for both the left (t 3.663; P`0.001) and right (t 3.742; P`0.001) feet whereby obese subjects displayed a reduced angle. Chippaux ± Smirak Index scores were also signi®cantly different for both the left (t 7 6.362; P`0.001) and right (t 7 5.675; P`0.001) feet between the two subject groups where a greater score for the obese subjects was evident. A decreased footprint angle and an increased Chippaux ± Smirak Index are characteristic of structural foot changes that have been associated with compromised foot function. CONCLUSIONS: Excess body mass appears to have a signi®cant effect on the foot structure of prepubescent children whereby young obese children display structural foot characteristics which may develop into problematic symptoms if excessive weight gain continues. Further investigation into possible consequences, particularly any effects on foot function, is warranted.

Many variables have been studied pertaining to the block sprint start. Research suggests that the adoption of a medium block spacing is preferred, with front and rear knee angles in the set position approximating 90 and 130 degrees, respectively, with the hips held moderately high. The sprinter must be capable of developing a high force rate combined with a high maximum force, especially in the horizontal direction. This ability to create high force underlies other important indicators of starting performance such as minimum block clearance time, maximum block leaving velocity and maximum block leaving acceleration. Once the sprinter has projected him/herself from the blocks at a low angle (40 to 45 degrees) relative to the ground, the following 2 post-block steps should occur with the total body centre of gravity ahead of the contacting foot at foot strike to minimise potential horizontal braking forces.

It was concluded that these changes in the kinematic and EMG parameters of sprint running primarily served as protective mechanisms to reduce stress placed on the hamstring muscles at critical phases of the stride cycle.

In the present study we investigated tension regulation in the human soleus (SOL) muscle during controlled lengthening and shortening actions. Eleven subjects performed plantar flexor efforts on an ankle torque motor through 30 degrees of ankle displacement (75 degrees -105 degrees internal ankle angle) at lengthening and shortening velocities of 5, 15 and 30 degrees. S(-1). To isolate the SOL from the remainder of the triceps surae, the subject's knee was flexed to 60 degrees during all trials. Voluntary plantar flexor efforts were performed under two test conditions: (1) maximal voluntary activation (MVA) of the SOL, and (2) constant submaximal voluntary activation (SVA) of the SOL. SVA trials were performed with direct visual feedback of the SOL electromyogram (EMG) at a level resulting in a torque output of 30% of isometric maximum. Angle-specific (90 degrees ankle angle) torque and EMG of the SOL, medial gastrocnemius (MG) and tibialis anterior (TA) were recorded. In seven subjects from the initial group, the test protocol was repeated under submaximal percutaneous electrical activation (SEA) of SOL (to 30% isometric maximal effort). Lengthening torques were significantly greater than shortening torques in all test conditions. Lengthening torques in MVA and SVA were independent of velocity and remained at the isometric level, whereas SEA torques were greater than isometric torques and increased at higher lengthening velocities. Shortening torques were lower than the isometric level for all conditions. However, whereas SVA and SEA torques decreased at higher velocities of shortening, MVA torques were independent of velocity. These results indicate velocity- and activation-type-specific tension regulation in the human SOL muscle.