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Biomedical subjects

D M Koceja

Publications and source records attributed to D M Koceja.

At least 37 records · Page 2Linked to original sources
PubMed1996

Age-dependent effects of muscle vibration and the Jendrassik maneuver on the patellar tendon reflex response.

OBJECTIVE: To explore possible effects of aging on the excitability of spinal reflexes. DESIGN: Using a cross-sectional design, the influences of muscle vibration and the Jendrassik maneuver on patellar tendon reflex function were compared between 30 young adults and 15 older adults. SETTING: Motor control research laboratory. SUBJECTS: The young adults were volunteers of college age. The older adults (74.5 +/- 4.14 yr) were volunteers from the local community. All subjects were free of medications and neurological conditions that would affect normal neuromuscular responses. MAIN OUTCOME MEASURES: A force-time curve analysis of the patellar tendon reflex response was used to assess the inhibition and facilitation of spinal reflexes. In the experimental protocol to assess spinal reflex inhibition, 100 Hz vibration was applied to the right quadriceps muscle. In another experimental protocol, spinal reflex facilitation was assessed using the Jendrassik maneuver. To perform the Jendrassik maneuver, subjects were instructed to grasp their hands together and to pull as hard as possible while breathing normally. After a 2-second count, the tendon tap was delivered to the right leg and the subject was instructed to relax. In both experimental protocols, control patellar tendon reflexes were collected. RESULTS: Analysis of variance for reflex peak force revealed a significant 30% reduction in the amount of vibration-induced reflex inhibition with increasing age, and a similar 33% reduction in the amount of Jendrassik maneuver facilitation observed for the older adults as compared with the younger adults. CONCLUSION: These results support the hypothesis that inhibitory and excitatory influences acting on the alpha motoneuron pool are different in young and older adults.

Adult↗
PubMed1996

Mood, neuromuscular function, and performance during training in female swimmers.

The effect of seasonal changes in training load on mood, neuromuscular function, and measures of physical power were examined in 12 collegiate women swimmers. These subjects were studied at three training stages during a competitive swim season: baseline (5,000 m.d-1), peak training (8,300 m.d-1), and taper (2,300 m.d-1). Mood was evaluated with the Profile of Mood States. Neuromuscular function was measured via the soleus Hoffmann-reflex (H-reflex). Anaerobic swimming power was assessed with a 30-s tethered swim test, and maximal aerobic power was determined following a maximal 378-m swim. Repeated measures ANOVA revealed that at peak training H-reflex and peak anaerobic swimming power were reduced (P < 0.05) below baseline values by 8.6% and 9.4%, respectively, and total mood disturbance was elevated above baseline (P < 0.01). These variables returned to baseline values at the taper assessment. H-reflex values were correlated with peak (r = 0.52, P < 0.01) and mean (r = 0.39, P < 0.05) anaerobic swimming power. Total mood disturbance was correlated (r = -0.34, P < 0.05) with mean swimming power. The results suggest that neurological mechanisms play a role in the adaptations that result from periodized training.

Adult↗
PubMed1995

The effects of vision and task complexity on Hoffmann reflex gain.

Previous research demonstrates modulation of the Hoffmann reflex amplitude and gain during changes in environmental conditions. H-reflex gain (defined in this study as the ratio of H-reflex amplitude to average soleus background EMG) is considered a functional measure of reflex modulation. In this study the effects of manipulating visual input and surface stability were to investigated in 17 subjects under four experimental conditions: (1) vision-stable surface, (2) no vision-stable surface, (3) vision-unstable surface, and (4) no vision-unstable surface. In each condition, subjects performed fifteen trials of a single leg stance for 7 s. The H-reflex was electrically elicited at the end of each trial by delivering a 1 ms square wave stimulation to the tibial nerve in the popliteal online for each trial (sampling rate = 2 kHz). An analysis of variance revealed significant decreases in H-reflex gain for the visual (F1.16 = 4.71, P < 0.05) and, surface conditions (F1.16 = 7.67, P < 0.05), however there was no interaction (F1.16 = 0.48, P < 0.05), between these variables. These results suggest that supraspinal mechanisms, possibly presynaptic inhibition, modulate H-reflex gain across environmental conditions. We conclude that visual and possibly cutaneous inputs were responsible for driving presynaptic inhibition and thus decreasing H-reflex gain.

Analysis of Variance↗
PubMed1995

Postural modulation of the soleus H reflex in young and old subjects.

The influence of different static postures on the soleus H reflex was assessed in 15 old (mean age = 76.3 years) and 10 young (mean age = 24.2 years) subjects. H reflex and M wave recruitment curves were obtained under 2 randomly administered conditions: (1) standing; and (2) prone. Once in place, the recording and stimulating electrodes were not removed until the completion of testing, to ensure that exact placement was maintained. A 1 msec current pulse was given transcutaneously to elicit the H reflex and M response. Static postural sway area (cm2) was assessed on a Kistler force platform using custom software (sample rate = 50 Hz/15 sec trials). Results demonstrated that the young subjects reduced the amplitude of the H reflex from the prone (Hmax/Mmax = 73.6%) to the standing (Hmax/Mmax = 59.9%) condition, whereas the old subjects did not (prone = 32.4%, standing = 38.2%). However, within the old group, 2 subgroups emerged--those who depressed the reflex similar to the young subjects (O-D, n = 6) and those who did not depress the reflex (O-ND, n = 9). Furthermore, there were significant differences in postural sway scores between the young and old, between the O-D and O-ND, but not between the O-D and young groups. These results suggest differences in the manner in which young and old subjects modulate the soleus H reflex when standing, and support the view that modulation of the stretch reflex may be important in the control of static posture.

Adult↗
PubMed1995

High school athletes and nutritional supplements: a study of knowledge and use.

Factors influencing nutritional supplement use by high school students were assessed. Comparisons were made between various groups of sports participants and non-sports participants. The Nutritional Supplement Use and Knowledge Scale was administered to 509 students. Mean supplement use score was 10.87 (SEM = 0.50, range 0-57). Mean knowledge score was 13.56 (SEM = 0.16, range 1-21). Significant relationships (p < .01) were obtained for supplement knowledge with use, and supplement use with gender. ANOVA found significant differences between supplement use by gender (p < .01), supplement use by sports category (p < .05), and knowledge scores by sports category (p < .01). Discriminant function analysis indicated knowledge, supplement use, and subscores for protein, vitamins/minerals, knowledge, supplement use, and subscores for protein, vitamins/minerals, and carbohydrates were best discriminators of sport group membership. Greater knowledge about supplements was associated with less use; hence, education about supplements can be a deterrent to use. This study may help coaches, athletic trainers, athletic directors, teachers, physicians, and parents identify nutritional misconceptions held by adolescents.

Adolescent↗
PubMed1995

Effects of auditory radio interference on a fine, continuous, open motor skill.

The effects of human speech on a fine, continuous, and open motor skill were examined. A tape of auditory human radio traffic was injected into a tank gunnery simulator during each training session for 4 wk. of training for 3 hr. a week. The dependent variables were identification time, fire time, kill time, systems errors, and acquisition errors. These were measured by the Unit Conduct Of Fire Trainer (UCOFT). The interference was interjected into the UCOFT Tank Table VIII gunnery test. A Solomon four-group design was used. A 2 x 2 analysis of variance was used to assess whether interference gunnery training resulted in improvements in interference posttest scores. During the first three weeks of training, the interference group committed 106% more systems errors and 75% more acquisition errors than the standard group. The interference training condition was associated with a significant improvement from pre- to posttest of 44% in over-all UCOFT scores; however, when examined on the posttest the standard training did not improve performance significantly over the same period. It was concluded that auditory radio interference degrades performance of this fine, continuous, open motor skill, and interference training appears to abate the effects of this degradation.

Attention↗
PubMed1994

Modulation of the triceps surae H-reflex with training.

Thirteen neurologically healthy adults were asked to balance on a specially designed balance board. This board allowed rotation in the sagittal plane only. Muscle activity of the triceps surae and tibialis anterior was sampled at 2 kHz and recorded. When the subject was balanced, soleus H-reflexes were elicited in the right leg with a constant-current stimulus pulse. The peak to peak amplitude of the soleus H-reflex served as the perturbation to the subject's balance as well as the dependent variable in question. Subjects performed three blocks (7 H-reflexes/block) of standing control trials with the balance board supported, and seven blocks of balancing trials. Prior to each block, maximal M-waves were recorded to ensure electrode stability across blocks. Results indicated that the subjects were able to significantly reduce (p < .001) the gain the soleus H-reflex while balancing and after the balance training. As a group, the subjects decreased their peak to peak amplitude of the soleus H-reflex by 26.2 percent from the initial standing block to the last balancing block. Moreover, subjects were also able to significantly reduce the gain of their standing control H-reflexes, supporting the notion of longer-term adaptability of the spinal stretch reflex. It is concluded that the progressive reduction in the H-reflex gain with short-term training may represent functional adaptation in the central nervous system.

Adolescent↗
PubMed1994

Postural sway patterns of normal men and women and men with mental retardation during a two-legged stance test.

Previous research has shown that in healthy subjects during a quiet two-legged stance, sagittal postural sway is greater than lateral postural sway with a ratio approximating 1.5. The purpose of this study was to examine the postural sway profiles of healthy men and women, and men with mental retardation (MR). Subjects consisted of 22 men (M), 22 women (W) and 22 men with MR. Postural sway characteristics were examined using a Kistler force platform. Each subject performed six trials, three with vision and three with vision occluded. Each trial was 15sec in duration, and the subject was instructed to stand motionless on the force platform. A custom-designed computer program sampled the lateral and sagittal sway characteristics for each trial, at a sample rate of 50Hz. Results indicated that the MR group exhibited significantly more lateral sway than the other two groups, and that the sagittal/lateral sway ratio was significantly lower in this group. Moreover, the MR group showed a greater amount of sway in the no-vision condition than either the M or W groups. Using the sagittal/lateral sway ratio, discriminant analyses indicated that group membership could be predicted in 75% to 82% of the cases in the vision condition, and 64% to 73% of the cases in the no-vision condition. It is concluded that the sagittal/lateral sway ratio provides a valid and objective assessment measure to determine the postural control/balance capacities of persons with MR. In addition, it is hypothesized that this ratio may prove useful in quantifying the effectiveness of therapeutic intervention programs on balance performance.

Adult↗
PubMed1993

Inhibition of the soleus H-reflex in standing man.

There exists evidence to support the notion that the segmental reflex system is not fixed and inflexible, but rather is highly modifiable under a variety of circumstances. In this study the H-wave and M-wave recruitment curves were obtained from 19 subjects, utilizing the procedures outlined by Hugon. Each subject was tested on one day under two randomly administered conditions: (1) standing; and (2) prone. Once in place, the recording and stimulating electrodes were not removed until the completion of the study, to ensure that exact placement was maintained. A percutaneous electrical stimulus (1 ms pulse) was utilized to elicit the pulse. The current was monitored with a current probe, and was increased in 2 mA increments from zero until a maximal M-wave was obtained. An analysis of variance revealed significant increases in the amplitude of the H-wave (P < 0.05) when the subject was prone with no significant increases in the M-wave. The results indicate significantly higher H/M ratios with the subjects in the prone position. Therefore, it is concluded that H-reflex amplitude is tonically depressed when the subject is maintaining a standing position.

Adult↗
PubMed1993

The relationship between body height extremes and the conditioned patellar tendon reflex response.

The purpose of this study was to determine the effects of extreme body heights on the conditioned patellar tendon reflex response in an attempt to differentiate between the contributions of supraspinal and spinal mechanisms on long-latency reflex facilitation. Unilateral and conditioned right patellar tendon reflexes were assessed in 10 extremely short males and females and 10 extremely tall males and females. The conditioning stimulus was a contralateral patellar tendon tap and the conditioning intervals were 10, 15, 25, 50, 60, 75, 100, 150, and 300 ms. There was a long-latency facilitation of quadriceps excitability beginning at the 75 ms conditioning interval regardless of the height of the subject. It is hypothesized that the similar conditioned patellar tendon recovery profiles in the extremely short subjects and the extremely tall subjects reflects the activation of a spinal polysynaptic pathway as the predominant mechanism for our long-latency reflex facilitation.

Adolescent↗
PubMed1993

Influence of quadriceps conditioning on soleus motoneuron excitability in young and old adults.

In an effort to investigate neuromuscular changes with age, the isometric force-time curve of the Achilles tendon-tap reflex (ATR) was measured in 10 college age (M = 20.9 yr) and 10 healthy active old subjects (M = 74.3 yr). In an effort to investigate spinal interneuronal pathways, the tendon-jerk was also conditioned with a tap to the ipsilateral or contralateral patellar tendon. The conditioning stimulus preceded the ATR by 25, 40, 55, 70, 85, 100, 115, 130, or 145 ms. Three trials were elicited at each conditioning interval plus three unilateral trials, for 30 trials per experimental session. Results indicated that the force production of the unilateral Achilles tendon-tap reflex was significantly reduced and the half-relaxation times were significantly lengthened in the old subjects. Moreover, ipsilateral conditioning produced short-latency facilitation and long-latency inhibition to the triceps surae in young subjects, whereas the same conditioning produced only a delayed long-latency inhibition in the old subjects. Similarly, the contralateral conditioning produced short-latency facilitation in the young subjects, with no changes observed in the old subjects. It is concluded that unilateral Achilles tendon-tap responses are different for the two groups, and that the reflex recovery profiles for the two groups are different. Several neurophysiological mechanisms are proposed to contribute to these differences.

Achilles Tendon↗
PubMed1992

Contralateral influences on triceps surae motoneuron excitability.

In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time curve of the tibial nerve H-reflex in 12 college age subjects. We also conditioned the reflex with a contralateral H-reflex stimulus or a contralateral tendon-tap, to ascertain the effects of crossed spinal segmental inputs on alpha motoneuron excitability. The conditioning stimulus preceded the test reflex by 10, 25, 40, 55, 70, 85, 100, 115, 130 or 145 msec. The results demonstrate that a conditioning tibial nerve H-reflex produced marked facilitation onto the contralateral triceps surae motoneurons, predominantly at longer-latency intervals. Conversely, a conditioning Achilles tendon-tap produced long-latency inhibition to the triceps surae. These results demonstrate that differential motoneuron excitability changes can be produced by electrical and mechanical conditioning stimuli. Moreover, these excitability changes may be long lasting and only appear after a relatively long latency. Several neurophysiological mechanisms are proposed to contribute to these changes.

Adult↗
PubMed1992

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-legged 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.

Adult↗
PubMed1992

Segmental reflex organization in endurance-trained athletes and untrained subjects.

In an effort to investigate the effects of training on spinal reflex pathways in humans, we measured the isometric force-time curve of the patellar (PTR) and Achilles (ATR) tendon-tap reflex in 12 endurance-trained (ET) athletes and 12 control (C) subjects. We also conditioned the tendon jerk with a contralateral or ipsilateral tendon-tap stimulus, to ascertain the effects of segmental inputs on crossed-spinal reflex activity. The conditioning stimulus preceded the test reflex by 25, 40, 55, 70, 85, 100, 115, 130, or 145 ms. The results demonstrated significant differences in control reflexes and conditioned reflexes between the two groups. A contralateral patellar tendon-tap produced a significantly greater excitatory effect to the contralateral quadriceps motoneurons for the ET group, whereas a contra- or ipsilateral conditioning caused a significantly greater inhibitory effect to the triceps surae motoneurons for the ET athletes. These results demonstrate that motoneuron excitability changes can be produced as a result of ipsi- and contralateral segmental inputs, and raise the possibility that trained athletes demonstrate different reflex recovery profiles. Several neurophysiological mechanisms are proposed to contribute to these changes.

Achilles Tendon↗
PubMed1991

Interactions in human quadriceps-triceps surae motoneuron pathways.

In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time curve of the patellar (PTR) and Achilles (ATR) tendon-tap reflex in 12 college age subjects. We also conditioned the tendon jerk with a contralateral or ipsilateral tendon-tap stimulus, to ascertain the effects of segmental inputs on crossed-spinal reflex activity. The conditioning stimulus preceded the test reflex by 25, 40, 55, 70, 85, 100, 115, 130 or 145 ms. The results demonstrate that a tap to the contralateral patellar tendon produced long-latency excitation of quadriceps motoneurons, but a tap to the contralateral Achilles tendon produced short-latency facilitation and long-latency inhibition of the triceps surae motoneurons. Also, a conditioning tap to the contra- or ipsilateral patellar tendon produced a brief short-latency facilitation that was followed by a distinct, long-latency inhibition of triceps surae motoneurons. These results demonstrate that motoneuron excitability changes can be produced as a result of ispi- and contralateral segmental inputs. Moreover, these excitability changes may be long-lasting and only appear after a relatively long-latency. Several neurophysiological mechanisms are proposed to contribute to these changes.

Achilles Tendon↗
PubMed1991

Organization of segmental reflexes in trained dancers.

Unilateral and conditioned Achilles tendontap reflex (ATR) characteristics were examined in a group of skilled dancers and a group of sedentary, untrained subjects (n = 7/group). For the conditioned reflex, the right ATR was conditioned by a tap to the left Achilles tendon using intervals of 10, 40, 70, 100, 130, 160 and 190 ms. Peak isometric force, contraction time and half-relaxation time were examined on each trial. The results indicated that the trained dancers exhibited less unilateral isometric force and longer half-relaxation times (p less than 0.05) than the untrained subjects. Moreover, the contralateral conditioning stimulus caused a more marked short-latency facilitation as well as a long-latency inhibition in the reflex force characteristics for the trained dancers when compared with the untrained subjects. These differences in both simple and conditioned reflexes in individuals trained for dance activities may reflect differences in muscle stiffness, tissue compliance or neural organization.

Achilles Tendon↗
PubMed1990

Quadriceps excitability is enhanced by a conditioning tap to the Achilles tendon.

In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time characteristics of the patellar tendon-tap reflex in ten college-age subjects. We also conditioned the tendon jerk with a tap to the contralateral Achilles tendon or the ipsilateral Achilles tendon. The results clearly demonstrated that a conditioning tap to the Achilles tendon produced a marked (greater than 200 percent) excitatory effect onto the quadriceps muscle. Also, this effect occurred sooner when the quadriceps was conditioned by an ipsilateral stimulus rather than a contralateral stimulus. It is concluded that in accord with other conditioning studies to date, the quadriceps muscle is characterized by a predominantly excitatory effect caused by a conditioning stimulus, and that this arousal is independent of the origin of the conditioning stimulus.

Achilles Tendon↗