Paul R. Surburg

Neuromuscular adaptations following prepubescent strength training.

Underlying mechanisms of prepubescent strength gains following resistance training are speculative. The purpose of this investigation was to determine the effects of 8 wk of resistance training on muscular strength, integrated EMG amplitude (IEMG), and arm anthropometrics of prepubescent youth. Sixteen subjects (8 males, 8 females) were randomly assigned to trained or control groups. All subjects (mean age = 10.3 yr) were of prepubertal status according to the criteria of Tanner. The trained group performed three sets (7-11 repetitions) of bicep curls with dumbbells three times per week for 8 wk. Pre- and posttraining measurements included isotonic and isokinetic strength of the elbow flexors, arm anthropometrics, and IEMG of the biceps brachii. Planned comparisons for a 2 x 2 (group by test) ANOVA model were used for data analysis. Significant isotonic (22.6%) and isokinetic (27.8%) strength gains were observed in the trained group without corresponding changes in arm circumference or skinfolds. The IEMG amplitude increased 16.8% (P < 0.05). The control group did not demonstrate any significant changes in the parameters measured. Early gains in muscular strength resulting from resistance training prepubescent children may be attributed to increased muscle activation.

Reliability of isokinetic and isometric measurement of leg strength on men with mental retardation

The purpose of this study was to determine the reliability of isokinetic and isometric measurement of strength for tests of knee extension and hip abduction on men with mental retardation (MR). In addition, the relationships between isokinetic measures of peak torque (PT) and total work (TW) and isometric peak torque were examined. Twenty-two men with mild to moderate MR were tested for isokinetic knee extension and hip abduction strength on a Musculoskeletal, Evaluation, Rehabilitation and Conditioning (MAREC) systems dynamometer at velocities of 60 and 30 degrees/sec, respectively. Isometric peak torque was determined by an examiner using a Nicholas Manual Muscle Tester (NMMT). Intrarater correlation coefficients for the isokinetic PT and TW scores ranged from .97 to .99, whereas coefficients for isometric NMMT scores ranged from .97 to .98. Pearson correlation coefficients between PT and TW scores ranged from .76 to .93. Coefficients between isokinetic and isometric scores ranged from .43 to .73. These results indicate that highly reliable isokinetic and isometric measurements can be obtained on men with MR. Also, the relatively simple measurement of PT may be the isokinetic parameter of choice at the clinical setting. Moderate relationships between NMMT and isokinetic scores were found, indicating that the generalization of test scores from one test modality to another is not warranted.

Midline-crossing Inhibition: An Indicator of Developmental Delay

In normal development midline crossing integration is usually attained by eight or nine years of age. The inability to attain this developmental milestone is called midline crossing inhibition (MCI). A new method to detect MCI was used to examine the presence of MCI in a group of subjects with mental retardation. Seventeen subjects with mental retardation and an equal number of non-disabled peers participated in the study. Choice response time measurements consisting of reaction time and movement time were the dependent variables. These variables were recorded when subjects executed ipsilateral, midline and contralateral movements with each leg. Analysis of data revealed for both dependent variables significant differences between the two groups of subjects. Only the group with mental retardation exhibited contralateral times that were significantly slower than ipsilateral times. Midline crossing inhibition was evident with these developmentally delayed subjects. This new method shows promise for assessing developmental and neurological anomalies.

CROSSING THE MIDLINE : A STUDY OF FOUR-YEAR-OLD CHILDREN

Midline crossing refers to behavior that results in reaching, stepping, or looking across the bodys midline. Several studies have indicated that infants, young children, and individuals with disability make more errors on midline-crossing tasks than on similar tasks placed at the ipsilateral side. Until recently, assessment of midline crossing has used a spatial protocol and has been criticized for not having a temporal component. The purpose of this study was to assess midline crossing by 9 4-yr.-old children within an information processing context. Analysis indicated that contralateral tasks required more processing time than similar tasks placed ipsilaterally.

Fundamental Gross Motor Skill Performance by Girls and Boys with Learning Disabilities

The purpose of this study was to compare the performance of fundamental gross motor skills by 10 girls and 10 boys, 7 yr. old, with learning disabilities. Their skills were assessed on the Test of Gross Motor Development. The boys achieved significantly higher mean scores than the girls on the subtests of Locomotor Skills and Object Control Skills, and on the Gross Motor Development Quotient.

Imagery and Physical Practice in the Acquisition of Gross Motor Timing of Coincidence by Adolescents with Mild Mental Retardation

The purpose of this study was to examine the effect of imagery practice in conjunction with physical practice on the performance of anticipating a coincidence (striking) by adolescents with mild mental retardation. 32 adolescents were randomly assigned to either a physical practice plus imagery practice group or a physical practice only group. Subjects in the physical practice plus imagery practice group were asked to image the task before physically performing it, while subjects in the physical practice only group did not image the task. Subjects performed 20 trials per day for five consecutive sessions (days). The physical practice plus imagery group performed with significantly greater accuracy and less variability than subjects in the physical practice only group, and subjects regardless of group affiliation were able to reduce error and variability over the study. These results support the use of imagery practice in conjunction with physical practice when performing a relevant anticipation of coincidence (striking) task as well as an aid in reducing performance variability. Based on the increased amount of cognitive-symbolic elements in the striking task as opposed to tasks used in previous studies, evidence is presented for support of the notion that imagery facilitates motor performance to the extent that cognitive-symbolic elements are present.

Effects of midline crossing on response processing of adults with mental retardation

In normal development, midline crossing inhibition (MCI) generally disappears by age nine. Individuals with mental retardation exhibit developmental delays which are manifested as failure to attain motor milestones. This study utilized a new methodology predicated upon a response processing model to measure MCI in 20 adults with moderate mental retardation. A chronologically equivalent group of individuals with mental retardation served as the control group. Measurements of reaction time (RT) and movement time were recorded as a subject performed ipsilateral, midline and contra-lateral movements. The rationale behind this experiment was that crossing midline to the contralateral side constituted a more complex task, requiring more response processing time and longer RTs. Analysis of the RT revealed inhibitory responses in the subjects with mental retardation when movements were made in a contralateral direction with the preferred hand. No inhibition was manifested by the subjects in the control group. This new method of assessing MCI detected this phenomenon with subjects who were mentally retarded.

Postural Sway Characteristics of Single Leg Stance in Men with Mental Retardation

This study examined the postural sway characteristics of 10 men with mental retardation and 10 each normal men and women during the one-logged stance test. Significant differences between the men with mental retardation and the other two groups were found on measures of lateral sway and on the sagittal sway:lateral sway ratio.

Effects of Occurrence and Time Uncertainties on Reaction and Movement Times of Children

This study investigated the influence of catch trial (CT) occurrence and foreperiod variation on reaction time and movement time of children of different ages. 48 children were randomly assigned to a CT group or a no-CT group. All received randomly ordered foreperiods. The presence of CTs and varying foreperiods played an inhibitory role in the motor performance of children.

Lower Extremity Response Time Performance in Boys With ADHD

Objective: Children with ADHD have been labeled as “uncoordinated” and “inefficient movers”; however, a paucity of research has systematically examined “stimulant-free” motor processing in this population. Method: In the present investigation, the authors employ a cross-lateral integration task to assess the attainment of a motor milestone in a corpus of 16 adolescents with ADHD acutely removed from their daily medication routine (methylphenidate) and 19 age-matched peers. Participants perform a choice response time task involving the lower extremity to targets located at midline and in ipsilateral and contralateral space. Results/Conclusion: This investigation finds that children with ADHD have slower lower extremity reaction and movement times compared to controls, and all preadolescent children demonstrate an inhibition in processing movements that require crossing the midline of the body. (J. of Att. Dis. 2007; 10(4) 343-349)