Biomedical subjects

K A Kubitz

Publications and source records attributed to K A Kubitz.

10 recordsLinked to original sources

PubMed1999

Effects of a proposed challenge on effort sense and cardiorespiratory responses during exercise.

PURPOSE: Highly trained endurance athletes train and race at relatively high intensities and are often confronted with challenges throughout a running event. The purpose of this study was to examine the effects of the anticipation of a proposed challenge on effort sense, heart rate (HR), ventilation ([dotVE), and ventilatory equivalent VE/VO2), a measure of ventilatory efficiency. METHODS: Highly trained endurance athletes (VO2max = 68.46 +/- 1.47 mL x kg(-1) x min(-1) ran two sessions at approximately 75% of VO2max for 35 min in a control condition and a proposed challenge condition. During the control condition, the subjects ran on a treadmill while simultaneously viewing a video depicting a runner exercising at 75% of VO2max and were told the run would continue at a speed that elicited 75% of VO2max. During the proposed challenge condition, subjects completed the same exercise protocol but viewed a video of a struggling runner and were told that the treadmill speed would be increased to "an extremely difficult" 95% of VO2max matching the intensity of the runner on the video. However, after data assessment at 17 min, subjects were told that the treadmill was malfunctioning and the treadmill speed could not be altered. The same intensity was maintained in both conditions. RPE, HR, VE, and VE/VO2 were assessed during the treadmill runs at 10, 17, 25, and 35 min. RESULTS: The effects of the manipulation were represented by a significant increase in state anxiety immediately following the video proposing the 95% challenge. RPE, HR, and VE increased similarly under both conditions, while VE/VO2 did not change. CONCLUSION: These findings suggest that for highly trained endurance athletes, anticipation of proposed challenge during running does not influence cardiorespiratory responses; thus these athletes demonstrate a "physiologically toughened" response.

Adaptation, Psychological↗

PubMed1996

EEG power spectral densities during and after cycle ergometer exercise.

This study examined the effects of aerobic exercise on spontaneous electroencephalographic (EEG) activity. Participants (N = 34) were asked to (a) sit quietly for a 10-min adaptation period, (b) either exercise on a cycle ergometer (n = 18) or watch a videotape (n = 16) for 15 min, and (c) sit quietly for a 10-min recovery period. EEGs were collected during the last 2 min of the adaptation period, the last 2 min of each 5-min stage of the exercise/videotape period, and the last 2 min of the recovery period. EEG power densities were combined across the alpha and beta frequency bands. The results indicated that brain activation increased (i.e., alpha activity decreased and beta activity increased) during the exercise condition and returned to baseline following exercise. This did not occur in the nonexercise condition. Thus, the results were consistent with the opponent-process theory (Solomon, 1980) in that brain activation increased during exercise.

Adaptation, Physiological↗

PubMed1996

The effects of acute and chronic exercise on sleep. A meta-analytic review.

Studies attempting to ascertain the effects of acute and chronic exercise on measures of sleep have yielded conflicting results and interpretations. Methodological differences among studies may explain this lack of consensus; however, small sample sizes and subsequently low statistical power may also have contributed. In an attempt to resolve these issues, this review used meta-analytical techniques to: (a) re-examine the effects of exercise on sleep; and (b) examine possible moderators of these effects. Studies meeting the selection criteria were included in the analysis. Analyses of moderating factors were performed for stage 4 sleep and rapid eye movement (REM) sleep. The results indicated that acute and chronic exercise increased slow wave sleep (SWS) and total sleep time but decreased sleep onset latency and REM sleep. Moderating variables influencing the magnitude and direction of these effects were related to characteristics of the individual (e.g. sex, age, fitness level) and the exercise (e.g. time of day exercise was completed, type of exercise, exercise duration). Mechanisms which have been suggested to explain the relationship between exercise and sleep are discussed and directions for further research are provided.

Exercise↗

PubMed1995

Anxiety responses to maximal exercise testing.

The influence of maximal exercise testing on state anxiety was examined in three separate studies. Highly trained male distance runners (Study 1, n = 12) as well as college students with average (Study 2, n = 16) and below average (Study 3, n = 32) physical fitness levels completed graded maximal exercise tests. This last group was also randomly assigned to either a control or an 8 week training programme in order to determine the effect of increased fitness on the psychological responses to maximal exercise testing. Physical fitness was determined by the measurement of maximal oxygen uptake. State anxiety (State-Trait Anxiety Inventory) was assessed before and from 2-15 min following exercise. It was found that the state anxiety responses to maximal exercise testing were not influenced by re-testing or by 8 weeks of endurance training. Across the three study groups, the anxiety response was variable during the first 5 min following exercise testing; increases, decreases and no changes in anxiety were observed when compared to pre-exercise levels. The anxiety response to maximal exercise appeared to be dependent on the pre-exercise anxiety levels as well as the timing of the post-exercise assessments. It is concluded that maximal exercise testing can be associated with negative mood shifts during the first 5 min after exercise; however, this response is transitory and followed by positive mood shifts 10-15 min following such tests.

Adult↗

PubMed1995

Effects of exercise on the coherence of human EEG signals at selected hemispheric sites.

This study investigated the effects of exercise on the intrahemispheric coherence of human electroencephalographic (EEG) signals. The frontal and temporal sites of each hemisphere (left: F3, T3; right: F4, T4) were selected as the sites to be compared. The subjects were divided into an exercise group and a control (nonexercise) group. Subjects rested for ten minutes; exercised on a cycle ergometer or watched a videotape for three consecutive five-minute periods, and then rested again for ten minutes. EEG recordings were taken during each of these five activity periods. The coherences between F3 and T3 and between F4 and T4 were calculated for each activity period. The coherence values were averaged across a specific frequency band (alpha, beta 1, or beta 2), and a randomized block-design test was applied to the z-transformed mean coherence values to determine whether any significant differences existed among the coherences within a particular frequency band. In the exercise group the right- and left-hemisphere alpha-band coherences for all three exercise periods were significantly decreased compared with the alpha-band coherence for the final rest period. In the control group the right-hemisphere beta 1-band coherences for the videotape periods were significantly decreased compared with the beta 1-band coherence for the initial rest period.

Adult↗

PubMed1991

A meta-analysis on the anxiety-reducing effects of acute and chronic exercise. Outcomes and mechanisms.

The relationship between exercise and anxiety has been extensively examined over the last 15 years. Three separate meta-analysis were conducted to quantitatively review the exercise-anxiety literature for state anxiety, trait anxiety and psychophysiological correlates of anxiety. Such a procedure allows tendencies of the research to be characterised. The results substantiate the claim that exercise is associated with reductions in anxiety, but only for aerobic forms of exercise. These effects were generally independent of both subject (i.e. age and health status) and descriptive characteristics. Numerous design characteristics were different, but these differences were not uniform across the 3 meta-analyses. For state anxiety, exercise was associated with reduced anxiety, but had effects similar to other known anxiety-reducing treatments (e.g. relaxation). The trait anxiety meta-analysis revealed that random assignment was important for achieving larger effects when compared to the use of intact groups. Training programmes also need to exceed 10 weeks before significant changes in trait anxiety occur. For psychophysiological correlates, cardiovascular measures of anxiety (e.g. blood pressure, heart rate) yielded significantly smaller effects than did other measures (e.g. EMG, EEG). The only variable that was significant across all 3 meta-analyses was exercise duration. Exercise of at least 21 minutes seems necessary to achieve reductions in state and trait anxiety, but there were variables confounding this relationship. As such, it remains to be seen what the minimum duration is necessary for anxiety reduction. Although exercise offers therapeutic benefits for reducing anxiety without the dangers or costs of drug therapy or psychotherapy, it remains to be determined precisely why exercise is associated with reductions in anxiety. Since several mechanisms may be operating simultaneously, future research should be designed with the idea of testing interactions between these mechanisms.

Acute Disease↗

PubMed1991

The influence of electrocortical biofeedback on performance in pre-elite archers.

The purpose of the present research was to determine whether EEG biofeedback training could improve archery performance as well as self-reported measures of concentration and self-confidence. Experienced pre-elite male (N = 16) and female (N = 8) archers were randomly assigned to one of three treatment conditions: (a) correct feedback (i.e., greater left hemisphere low frequency activity), (b) incorrect feedback (i.e., greater right hemisphere low frequency activity), and (c) no feedback control. The pretest and posttest consisted of 27 shots, with EEG data collected for the left and right temporal hemispheres (T3, T4). Feedback subjects were then given EEG biofeedback, while control subjects rested for 30 min. Analyses indicated that only the performance measure was significant. The correct feedback group significantly improved performance, while the incorrect feedback group showed a significant performance decrement from pre- to posttest (Ps less than 0.05). The control group showed no significant pre-post differences in performance. EEG analyses showed differences that were consistent with the training given to the incorrect, but not the correct, feedback group. Overall, the results provide some support for the use of known relationships between EEG and performance as an effective means of providing biofeedback to affect the performance of pre-elite archers.

Attention↗

PubMed1990

Hemispheric asymmetry, cardiac response, and performance in elite archers.

Previous sport research on elite athletes has shown systematic changes in psychophysiological measures, such as heart rate (HR) deceleration and hemispheric asymmetries in EEG activity, in the few seconds prior to executing a motor response. These changes are believed to be due to a more focused attention on the external environment. Using archery (an attentive state), this investigation was designed to examine: (a) whether hemispheric asymmetry and HR deceleration would occur during the aiming period, and (b) if they did, whether this would affect performance. HR and left and right temporal EEG were recorded from 28 right-handed elite archers for 16 shots. The results indicated that (a) there was no HR deceleration; (b) during the aiming period, EEG alpha activity formed the dominant frequency and this was significantly greater in the left than in the right hemisphere; (c) there were no significant right hemisphere EEG changes in spectral power from 3 s before the shot to arrow release, but there were significant left hemisphere increases at 10, 12, and 24 Hz; and (d) at 1 s prior to the shot, there were no significant right hemisphere spectral power differences between best and worst shots, but there were significant left hemisphere differences at 6, 12, and 28 Hz. The relationships among hemispheric asymmetry, HR deceleration, attentional processes, and shooting performance are discussed.

Adolescent↗

PubMed1987

A comparison of two methods of training resistance to visually-induced motion sickness.

This report concerns the use of two methods of training subjects to tolerate visually-induced motion sickness (VMS). Sixteen subjects were selected on the basis of their response to a motion sickness history questionnaire and assigned to one of four groups on the basis of their ability to tolerate visually-induced motion (VM). One group received 10 sessions of confidence building and desensitization training (BT); a second group received 10 sessions of EMG and temperature biofeedback (FB); a third group received 10 sessions of BT and 10 sessions of FB (BTFB); and a fourth group received no treatment (C). The results indicated that the BT and BTFB groups exhibited significant increases in tolerance to VM when pretreatment measures were compared to posttreatment measures, while no significant differences in pre-post measures were observed in the FB or C groups. A similar pattern emerged from the symptomatology data.

Behavior Therapy↗

PubMed1986

The effect of daily Hassles of humoral immunity: an interaction moderated by locus of control.

Research has shown that stress is associated with depressed cellular immune functioning. Controversy exists as to whether humoral immunity shows a similar depression under stress. Several psychological variables have been found to moderate responses to stress. In particular, an internal locus of control has been correlated with better health. The present study examined the level of salivary immunoglobulin A (IgA) and health locus of control in subjects with high and low stress levels. The Hassles scale was administered to identify two subject groups differing significantly in reported stress levels. Results showed no significant differences between the two groups on salivary IgA. There was a significant negative correlation between IgA and internal locus of control. The direction of this correlation is in contrast with previous findings on internality. The evidence suggests that high internal individuals may be especially vulnerable to high levels of stress, particularly stress that they cannot control. Also, there was a significant difference in IgA levels between females depending on whether they were in the first or the second half of their menstrual cycle. Those in the premenstrual phase had lower IgA levels.

Adult↗