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Biomedical subjects

L N Burkett

Publications and source records attributed to L N Burkett.

11 recordsLinked to original sources
PubMed1990

Exercise capacity of untrained spinal cord injured individuals and the relationship of peak oxygen uptake to level of injury.

Twenty spinal cord injured individuals were tested for maximal oxygen uptake (VO2 peak using a hysteresis brake wheelchair ergometer. The subjects were divided into 4 groups as follows: (a) quadriplegics (4 subjects); (b) untrained female paraplegics (5 subjects); (c) untrained male paraplegics (7 subjects); and (d) trained male paraplegics (4 subjects). The VO2 peak were analysed by a one way ANOVA and Fisher's LSD multiple comparisons. The F-ratio (50.93) was significant (p = less than 0.0001). Fisher's LSD post hoc multiple comparisons found the following differences: (a) quadriplegics were significantly lower than the untrained paraplegic females, untrained paraplegic males and trained paraplegic males; (b) untrained females were significantly lower than the untrained male paraplegics, and trained paraplegic males; (c) untrained paraplegic males were significantly lower than the trained male paraplegics. A Spearman Rho correlation was calculated using injury level and VO2 max for all the untrained SCI individuals. The correlation was 0.68 and had a significance level of 0.0019. The present study combined with the known research literature gives strong evidence that VO2 peak in the untrained SCI is highly related to level of injury.

Exercise Test↗
PubMed1990

Maximal exercise testing of mentally retarded adolescents and adults: reliability study.

Few data are available regarding maximal exercise testing of mentally retarded individuals. No data are available on the reliability of maximal exercise testing of mentally retarded individuals. The purpose of this study was to determine the reliability of graded exercise testing of mentally retarded adolescents and adults. The testing was conducted at two geographically different centers. At Center A, 14 mentally retarded adolescents (11 boys, three girls) with Down syndrome, who were educable or trainable, were recruited from a nonresidential school. The subjects completed two Balke-Ware treadmill protocols until exhaustion. The treadmill time and heart rate (HR) were recorded. The time between tests was approximately one week. At Center B, 21 mentally retarded adults (14 women, seven men means IQ = 56) were recruited from local workshops and group homes. These subjects completed a treadmill walking protocol, with metabolic measurements, until exhaustion. The time between tests varied from one to four months. At Center A, the subjects achieved a mean treadmill time of 8.72min on test one and 8.84min on test two (means HR = 174 and 175bpm, respectively). The reliability coefficient between the two tests was .94. At Center B, the subjects achieved a mean V0(2)max of 27.2mL.kg-1.min-1 on test one and 26.9mL.kg-1.min-1 on test two. The reliability coefficient was .93. These data show that maximal exercise testing is reliable for these populations of mentally retarded individuals, exhibiting similar values to their nonretarded peers.

Adolescent↗
PubMed1986

The effect of training on exercise-induced R-wave amplitude changes in young females.

The effects of an exercise training program on R-wave amplitude (Ramp) changes during graded exercise were investigated in 14 adolescent females. The experimental group (EG) (N = 6) underwent a 20-wk aerobic exercise program. Eight subjects served as controls (CG). Oxygen uptake (VO2), heart rate (HR), and Ramp were determined during incremental exercise to exhaustion, pre- and post-program. The Ramp was calculated by using the average of 10 electrocardiographic complexes to provide a stable criterion. Pre-training, EG and CG were not significantly different for VO2max and HRmax; Ramp decreased significantly between rest and 5 min prior to exhaustion for both groups (P less than 0.05). Ramp changes were significant between the first min of exercise and 2 min prior to exhaustion for EG (P less than 0.05) and between the first min of exercise and 1 min prior to exhaustion for CG (P less than 0.05). These changes occurred at 87% of VO2max and 95% of HRmax for EG and at 93% of VO2max and 97% of HRmax for CG. CG showed no change in these variables post-program except for Ramp exhibiting a significant change between rest and the first min of exercise (P less than 0.05). EG showed a significant increase in VO2max (P less than 0.05), and Ramp changes during exercise were delayed. The first significant change occurred between rest and 3 min prior to exhaustion (P less than 0.05), and the second change occurred between the first min of exercise and exhaustion (P less than 0.05). Thus the latter Ramp change was delayed to 100% of VO2max and HRmax post-training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Effects of shoes and foot orthotics on VO2 and selected frontal plane knee kinematics.

The objective of this study was to investigate the effects of shoes and foot orthotics on running economy and selected frontal plane knee kinematics during the support phase of running. Twenty-one male runners who had been fitted with orthotics served as subjects. Subjects participated in three submaximal runs on a treadmill under the following conditions: barefoot, shoes, and shoes plus orthotics. A run consisted of 1 min at 161 m . min-1, 2 min at 180 m . min-1, and 4 min at 201 m . min-1. VO2 was calculated for the last 3 min of each test. Frontal plane motion was filmed during the sixth min of each submaximal run, and linear and angular displacement of the knee were then calculated from film data. Results from the mechanical aspect of this study indicate that there were no significant differences among the means for linear displacement of the knee. Angular displacement of the knee during barefoot running was significantly (P less than 0.05) less than shoe and shoe-plus-orthotic conditions. There was no difference, however, between shoes and shoes plus orthotics. The economy results revealed that the aerobic cost of running increased as the amount of mass added to the foot increased. In absolute terms (1 . min-1), running in shoes plus orthotics was significantly (P less than 0.05) more costly than running barefoot. It appears that if orthotics do, in fact, improve running economy by improving running mechanics, the amount of improvement is negated by the additional cost of running associated with the mass of the orthotics.

Energy Metabolism↗
PubMed1978

Field testing of cardiorespiratory fitness in primary school children.

The purpose of the investigation was to explore the validity of using timed distance runs as predictors of cardiorespiratory fitness in first, second and third grade children. Maximal oxygen uptake (Vo2 max), determined via the open-circut method during treadmill running, and performance on runs of 800, 1200 and 1600 meters were compared for 83 children. Males were found to exceed females on Vo2 max and possessed significantly faster times on all the distances run. The 1600-meter run proved to be the best predictor of Vo2 max (ml/kg) in both sexes. Test-retest reliability of the 1600-meter run was checked with 120 students and found to range from +.824 for first grade females to + .918 for third grade males. Normative values for first, second, and third grade students were calculated from data collected on 1440 elementary students. All subjects studied had previously received instruction and practice on the phenomenon of paced distance running.

Child↗
PubMed1977

Field estimation of VO2 max in children eight years of age.

The purpose of the investigation was to explore the validity of using timed distance runs as predictorr of cardiorespiratory fitness in young untrained children. Maximal oxygen consumption and performance in runs of 549, 1207, and 1609 meters (600 yards, 3/4 mile, and 1 mile) were compared in 38 children eight years of age. Males were found to exceed females on Vo2max and possessed significantly faster times in the 1207 and 1609 meter runs. The females exhibited greater six-site skinfold totals. The 1609 meter run proved to be the best predictor of Vo2max (ml/kg) in males. However, none of the three distances was acceptable for females.

Adolescent↗
PubMedDate not supplied

Investigation into hamstring strains: the case of the hybrid muscle.

Past research on hamstring strains indicated an imbalance in leg strength as a cause of hamstring strains. No theory has been put forth to explain why the strength imbalance would cause strain. Investigation on cadavers of the muscular attachment of the short head of the biceps femoris indicated the varied attachment of this muscle to the linea aspera. It is theorized that an extensive attachment to the linea aspara and a strength imbalance would cause hamstring strains.

Biomechanical Phenomena↗