Gross motor skills involve the large muscles of the body that enable major body movement such as walking, jumping, reaching, and maintaining balance and coordination. Gross motor skills depend on both muscle tone and strength. Children with better-developed motor skills may find it easier to be active and engage in more physical activity than those with less-developed motor skills. Children with poorer motor skill performance have been found to be less active than children with better-developed motor skills1-9. The relationship between motor skill performance and physical activity may be important to the health of children. The Test of Gross Motor Development – Second Edition(TGMD2) (http: //www.proedinc.com/customer/productView.aspx?ID=1776) was used to test the motor skills of all children aged 3-5 years who participated in the National Health and Nutrition Examination Survey’s (NHANES) National Youth Fitness Survey (NNYFS).
Participants aged 3-5 years, who do not meet any of the exclusion criteria, were eligible for this component. Participants were excluded from this component if they had physical limitations requiring a wheelchair; amputations of the leg, foot, arm, or hand; paralysis of one or both arms or hands; hand/arm/shoulder/leg surgery in last 3 months; or mental impairment.
The TGMD-2 is composed of two subtests for gross motor development––Locomotor and Object Control––both of which have six skills that assess a different aspect of gross motor development. For each of these six skills, there are between 3 and 5 criteria to assess the skill. The locomotor subset measures run (4 criteria), gallop (4 criteria), hop (5 criteria), leap (3 criteria), horizontal jump (4 criteria) and slide (4 criteria). The object control subset measures striking a stationary ball (5 criteria), stationary dribble (4 criteria), kick (4 criteria), catch (3 criteria), overhand throw (4 criteria), and underhand roll (4 criteria).
Standardized procedures were followed in order to compare a child’s scores to those made by peers in the normative sample. The following requirements are standard for administering the tests most reliably in an attempt to minimize any discriminatory practices by ensuring that the participant understands the examiner’s directions.
• Give an accurate demonstration and verbal description of the skill to the participant prior to allowing the participant to perform it.
• Provide a practice trial to ensure that the participant understands what to do.
• Provide an additional demonstration when the participant does not appear to understand the task.
• Administer two test trials and score each performance criterion on each trial.
Each gross motor skill includes several behavioral components that are presented as performance criteria in TGMD-2 procedures manual (
https://www.cdc.gov/nchs/data/nnyfs/tgmd.pdf). For example, performance criteria for the run are (1) arms move in opposition to legs, elbows bent; (2) brief period where both feet are off the ground; (3) narrow foot placement landing on heel or toe (i.e., not flat-footed); and (4) nonsupport leg bent approximately at 90 degrees (i.e., close to buttocks). If the child performed a performance criterion correctly, the examiner recorded a “1.” If the child did not perform a performance criterion correctly, the examiner recorded a “0.” Partial scores to show that the child displays the criterion, but is inconsistent, were not allowed. If the participant refuses to perform the skill, he or she was coded “missing”.
After completing the procedure for each of the two trials, the two results for each criteria were added. The summed values for the locomotor criteria are reported in the dataset as: TGQR1S, TGQR2S, TGQR3S, TGQR4S, TGQG1S, TGQG2S, TGQG3S, TGQG4S, TGQH1S, TGQH2S, TGQH3S, TGQH4S, TGQH5S, TGQL1S, TGQL2S, TGQL3S, TGQJ1S, TGQJ2S, TGQJ3S, TGQJ4S, TGQS1S, TGQS2S, TGQS3S, and TGQS4S. The summed values for the object control criteria are reported in the dataset as: TGQB1S, TGQB2S, TGQB3S, TGQB4S, TGQB5S, TGQD1S, TGQD2S, TGQD3S, TGQD4S, TGQC1S, TGQC2S, TGQC3S, TGQK1S, TGQK2S, TGQK3S, TGQK4S, TGQT1S, TGQT2S, TGQT3S, TGQT4S, TGQU1S, TGQU2S, TGQU3S, and TGQU4S.
A raw subset score for locomotor (TGRAWLOC) and object control (TGRAWOBJ) were calculated by adding the summed values for the respective criteria. A locomotor standard score (TGSSLOC), object control standard score (TGSSOBJ), and overall Gross Motor Quotient (TGQUOTNT) were assigned based on Dale A. Ulrich’s Test of Gross Motor Development, Second Edition. Gross Motor Quotient was calculated for participants with complete locomotor and object control standard scores.
In converting to standard scores and the Gross Motor Quotient, the age in months at time of examination was used.
Detailed description of the protocol are provided in the Test of Gross Motor Development Procedures Manual available on the NNYFS website at:
https://www.cdc.gov/nchs/data/nnyfs/tgmd.pdf
Examiners were trained in administering this component prior to the start of the NHANES National Youth Fitness Survey, and quality control checks were made during field visits by NHANES and survey operations staff.
Edits were made where necessary to ensure the completeness, consistency, and analytic usefulness of the data.