Biomedical subjects

C D Davlin

Publications and source records attributed to C D Davlin.

4 recordsLinked to original sources

PubMed2001

The role of vision in control of orientation in a back tuck somersault.

During a back tuck somersault, the angular velocity of the head is thought to surpass the visual system's ability to maintain a distinct and continuous picture of the environment. The primary objectives of this research were to determine if differences existed with regard to trunk and lower body kinematics, as well as landing balance, when gymnasts perform back tuck somersaults under different vision conditions. Ten female gymnasts (age = 11.6 +/- 2.67 years, competitive level = 8 +/- 1.15, and training time in gymnastics = 5.9 +/- 1.63 years) performed back tuck somersaults under 4 vision conditions while wearing electromagnetic sensors that allowed automatic digitizing. Although no significant differences were found between vision conditions with regard to timing, joint angles, and joint angular velocities, gymnasts were more stable at landing under conditions that allowed vision during either the entire somersault or the last half of the sumersault.

Acceleration↗

PubMed2001

Peripheral vision and back tuck somersaults.

Although vision appears to enhance performance of somersaulting skills, few studies have investigated the source (foveal or ambient) of useful visual cues that can potentially be used by gymnasts during a somersault. Therefore, the primary objectives were to investigate the possible role of peripheral vision in the control of orientation and landing balance in a back tuck somersault. 10 female gymnasts (age = 11.6 +/- 2.7 yr., competitive level = 8 +/- 1.2, training time in gymnastics = 5.9 +/- 1.6 yr.) performed back tuck somersaults under four visual conditions (full visual field, horizontal peripheral vision limited to 100 degrees, horizonal peripheral vision limited to 60 degrees, and no vision) while wearing electromagnetic sensors that allowed automatic digitizing. Analysis yielded no statistically significant difference on any of the kinematic variables among vision conditions. Despite limiting the gymnasts' available horizontal peripheral vision, joint angles, angular velocities, and timing remained very similar. There were no statistically significant differences in landing balance between the conditions of full vision, 100 degrees peripheral vision, and 60 peripheral vision. However, gymnasts were less stable at landing when vision was absent as compared to the three other vision conditions.

Adolescent↗

PubMed1999

The effect of hip position and electromyographic biofeedback training on the vastus medialis oblique: vastus lateralis ratio.

OBJECTIVE: PATELLOFEMORAL PAIN SYNDROME IS A PATELLAR TRACKING DYSFUNCTION USUALLY ASSOCIATED WITH VASTUS MEDIALIS OBLIQUE (VMO) WEAKNESS, AND SUBSEQUENTLY, A SMALL VMO: vastus lateralis (VL) ratio. Several early electromyographic (EMG) studies have defined specific limb positions (such as external rotation of the hip) that preferentially activate the VMO. However, whether preferential activation of the VMO successfully translates into increased VMO:VL ratios with training has not been investigated. The purpose of our study was to investigate the effects of hip rotation on the mean VMO:VL EMG ratio using EMG biofeedback training over a 5-day period. DESIGN AND SETTING: Subjects performed isometric quadriceps contractions, in terminal extension, in 1 of 3 hip positions: the anatomically neutral hip position (group A), external hip rotation (group B), and internal hip rotation (group C). Pretest to posttest data were analyzed with a 3 (group) x 2 (test) analysis of variance with repeated measures on the last factor. SUBJECTS: Thirty-six healthy female college students with no known right knee musculoskeletal dysfunction. MEASUREMENTS: Activity of the VMO and VL was recorded by EMG and reported as the VMO:VL ratio. RESULTS: The main effect for group was not significant, but the main effect for test was significant. No significant interaction between group and test was noted. CONCLUSIONS: The statistical analysis of our results suggests that hip position during EMG biofeedback training has no effect on the VMO:VL ratio. However, because subjects were able to significantly increase their VMO:VL ratio in 5 days regardless of hip position, EMG biofeedback can be recommended for the facilitation of VMO muscular recruitment.

Journal Article↗

PubMed1999

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Journal Article↗