Ronald V. Croce

Reliability and Concurrent Validity of the Movement Assessment Battery for Children

Reliability and concurrent validity of the Movement Assessment Battery for Children were evaluated with a sample of 106 boys and girls, distributed into four age groups: 5–6 yr. (n = 20), 7–8 yr. (n = 20), 9–10 yr. (n = 46), and 11–12 yr. (n = 20). Test-retest reliability of the Movement Assessment Battery for Children, estimated using intraclass correlation coefficients, was high across all age groups, and concurrent validity yielded moderate Pearson correlation coefficients between the Movement battery and long and short forms of the Bruininks-Oseretsky Test of Motor Proficiency. These results support the use of the Movement battery as a measure of motor ability in children, ages 5 to 12 years.

Peak Torque, average power, and hamstring/quadriceps ratios in nondisabled adults and adults with mental retardation

OBJECTIVE To compare isokinetic hamstring and quadriceps peak torque (Nm), average power (watts), and corresponding hamstring/quadriceps (HQ) ratios (as percentages) of adult men with Down syndrome(DS), with mental retardation without Down syndrome (NDS), and nondisabled sedentary controls (SC). DESIGN Repeated measures analysis of variance. SETTING Subjects were tested at a university exercise science laboratory. SUBJECTS Volunteer sample of 35 subjects: SC(n=13), DS(n=9), and NDS (n=13). INTERVENTION Subjects performed isokinetic strength tests at 60 degrees /sec and 90 degrees/sec using gravity effected torque procedures. Subjects with DS and NDS performed the test on two separate days with best results selected for statistical comparisons. Sedentary controls performed the test once. MAIN OUTCOME MEASURES Isokinetic hamstring and quadriceps peak torque and average power, and corresponding HQ ratios on a Cybex 340 isokinetic dynamometer. RESULTS In all isokinetic parameters measured, sedentary controls demonstrated significantly higher scores than subjects with DS and NDS. There was no significant difference between subjects with DS and NDS, although mean peak torque and average power scores were greater in subjects with NDS. Finally, there were no significant differences in peak torque and average power HQ ratios across groups (p> .01), although group mean peak torque HQ ratios were greatest for sedentary controls (range=61% to 63%) and approximated accepted HQ ratio norms, and lowest for subjects with DS(range=40% to 46%). CONCLUSIONS Individuals with mental retardation are in need of progressive resistance exercise programs to improve hamstring and quadriceps strength and normalize HQ strength and power ratios.

Reciprocal coactivation patterns of the medial and lateral quadriceps and hamstrings during slow, medium and high speed isokinetic movements

The effect of movement velocity and fatigue on the reciprocal coactivation of the quadriceps and hamstrings was investigated through analysis of the root mean square (RMS) and the median frequency (MDF) of surface electromyography for the vastus medialis (VM), vastus lateralis (VL), medial hamstrings (MH) and biceps femoris (BF). Fourteen subjects performed six continuous isokinetic knee extension and flexion movements at 60 degrees, 180 degrees and 300 degrees s(-1), and 30 continuous movements at 300 degrees s(-1) to examine muscular fatigue patterns. Statistical analyses revealed that the RMS activity of the VM displayed greater coactivation than the VL (P<0.01) and the BF displayed greater coactivation than the MH (P<0.0001). There was no effect of velocity on the coactivation levels of the VM, the VL, or the MH; however, there was an effect of velocity on the coactivation levels of the BF (P<0.0001). Relative to MDF activity, the MH shifted upward as velocity increased (P<0. 01) while the BF decreased between 180 and 300 degrees s(-1) (P<0. 01). Results of the muscular fatigue test indicated that the RMS activity of the VM showed a higher degree of coactivation than the VL (P<0.01) and the BF showed approximately three times the coactivation level of the MH (P<0.001). The MDF of the VL and MH shifted downward as the repetitions progressed (P<0.01) with no changes for the VM or for the BF. Results of this study suggest that during isokinetic testing, both the VM and BF have significantly greater reciprocal coactivation levels when compared to the VL and MH, respectively. In addition, these results suggest that motor unit recruitment patterns of the VM and VL and the MH and BF differ with regard to the effects of velocity and fatigue.

The effects of EMG biofeedback on strength acquisition.

This study investigated the effectiveness of electromyographic (EMG) biofeedback in maximizing strength gains and integrated electromyographic (IEMG) levels of the quadriceps muscle group resulting from an isokinetic exercise program. Twenty-one male volunteers recruited from physical education classes at a large southwestern university were randomly assigned to one of the following three treatment groups: (1) a biofeedback (BF) trained group, (2) a deception (DEC) trained group, and (3) a nonfeedback (NF) trained group. Subjects were trained and tested for strength by extension on a Cybex Isokinetic Exercise Machine at a speed of 30 degrees per second. Training sessions were performed three times per week for five weeks; pretest and posttest data were based on the best score of three trials of a 1-RM maximum effort. A pretraining to posttraining comparison indicated significant increases in strength (p<.001)and IEMG levels (p<.001) for all treatment groups when a pairedt test was applied to the data. A multivariate analysis of covariance (MANCOVA) revealed that the BF trained group showed significantly greater peak torque values than DEC and NF trained groups (p<.01) and produced significantly greater IEMG levels than the NF trained group (p<.05). Overall, these results were taken as supporting the hypothesis that a training program of combined isokinetics and EMG biofeedback produces significant gains in maximal force and IEMG activity of leg-extensor muscles.

Effects of Collaborative Peer Tutoring on Urban Seventh Graders.

Abstract The effects of a collaborative peer tutor teaching program on the self-concept and school-based attitudes of seventh-grade students at a large urban junior high school were explored. Many of the students in the sample had been previously identified to be at risk by traditional school identification strategies. The study consisted of the 282 subjects enrolled in the seventh grade at F.C. Hammond Junior High School in Alexandria, Virginia. The Piers-Harris Self-Concept Scale was used to measure self-concept in subjects. The Demos D (Dropout) Scale was used to measure student tendency to drop out of school. Data were collected at two points during the 16-week period (immediately before program onset and immediately after program completion. A post hoc analysis revealed that students in the collaborative peer tutor teaching program demonstrated significant improvement in dropout scores compared with students in both the traditional class using group learning activities and the traditional class using...

Wavelet analysis of quadriceps power spectra and amplitude under varying levels of contraction intensity and velocity

Introduction: We investigated the effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity (50°, 100°, 200°, and 400°/s) on surface electromyography root mean square amplitude (SEMGRMS) and median frequency (SEMGMDF) of rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM). Methods: SEMGs during knee extension were resolved into their respective frequencies using wavelet transformations. Results: RF, VL, and VM muscles displayed increased SEMGMDF as contraction intensity increased from 25% to 50% MVC and from 75% to 100% MVC, and each muscle displayed its own unique frequency shifting patterns. The SEMGMDF was not influenced by movement velocity. SEMGRMS increased in all 3 muscles as contraction intensity increased and was influenced by movement velocity, with the highest values observed at 400° and 200°/s. Conclusions: We infer that increasing contraction intensity facilitates greater recruitment of fast‐twitch muscle fibers, but there are differing responses in RF, VL, and VM muscles. Muscle Nerve 50: 844–853, 2014

Comparison of Isokinetic Peak Force and Power in Adults with Partial and Total Blindness

For many populations the ability to move efficiently is compromised by an impaired muscular functioning. Strength development is necessary to overcome the effects of gravity to maintain posture and generate movement responses for mobility. The strength and power capabilities of individuals with total blindness (n=12) were compared to those with partial vision (n=12) to evaluate effects of vision on performance. Results indicate that (1) no significant differences were apparent between total blindness and partial vision, (2) significant sex differences were evident in each group, and (3) better performance was apparent at lower velocities. It was concluded that physical performance in individuals with blindness and partial vision are equally deficient.

Augmented Feedback for Enhanced Skill Acquisition in Individuals with Traumatic Brain Injury

Coincident timing by individuals who exhibit traumatic brain injury was measured under conditions of no knowledge of results (no KR; n = 12), KR on every trial (n = 14), summary KR (n = 13), and average KR (n = 12). Following acquisition trials, groups performed immediate and longer retention trials without KR. Absolute constant error and variable error, analyzed in separate repeated-measures analyses of variance, indicated that during acquisition trials subjects receiving KR on every trial were the most accurate and the most consistent in their responses; however, subjects in groups receiving summary and average KR were the most accurate during immediate retention, with the group receiving summary KR being the most accurate during longer retention.

Contraction intensity and velocity on vastus lateralis SEMG power spectrum and amplitude.

Effect of contraction intensity [100%, 75%, 50%, and 25% maximum voluntary contraction (MVC)] and movement velocity [0° (isometric)], 50°, 100°, 200°, and 400°/sec. [isovelocities]) on root mean square amplitude (SEMG–RMS) and median frequency power spectrum (SEMG–MNF) of vastus lateralis (VL) surface electromyography was investigated with ten healthy female university students. Peak torque (PT), mean torque (MT), SEMG–MNF, and SEMG–RMS, analyzed using separate repeated-measures analyses of variance (p ≤ .05), indicated: (1) an inverse relation between PT and MT and movement velocity, (2) greater SEMG–MNF values during all isovelocity conditions compared with isometric conditions, with highest values occurring at 50°/sec. and at 100% and 75% MVC, and (3) at all contraction intensities SEMG–RMS values were higher during dynamic movements than isometric movements and highest at 200° / sec. Isovelocity contractions were inferred to facilitate a greater recruitment of fast-twitch fibers (via increased SEMG–MNF), which was intensified at 50°/sec, whereas greater overall muscle activation was found at 200° / sec.

Coincident Timing by Nondisabled, Mentally Retarded, and Traumatic Brain-Injured Individuals under Varying Target-Exposure Conditions

Coincident timing by 15 nondisabled individuals, 15 mentally retarded and 15 traumatically brain injured was measured under varying target-exposure conditions. Absolute constant error, constant error, and variable error were analyzed in separate repeated-measures analyses of variance for early performance (first block of practice), late performance (last block of practice), and retention (last block of retention). Subjects with mental retardation displayed the least accurate and most variable coincident-timing responses. Nondisabled subjects were most influenced by target-exposure time; subjects with traumatic brain injury were most influenced by target-viewing distance; and subjects with mental retardation were most influenced by a combination of target velocity and target-viewing distance. Subjects with mental retardation displayed a too-early response bias, while nondisabled subjects tended to have a too-late response bias. Individuals with traumatic brain injury had a variable response bias.