The effect of breast support on upper body muscle activity during 5 km treadmill running

Breast support has previously been shown to influence surface EMG of the pectoralis major during running. Reductions in muscle activity have previously been associated with a reduction in energy cost, which may be advantageous for female runners. Ten female participants performed two self-paced (average pace 9 km h⁻¹) 5 km treadmill runs under two breast support conditions (low and high); an additional bare-breasted 2 min run was also conducted. Surface EMG electrodes were positioned on the pectoralis major, anterior deltoid, medial deltoid, and upper trapezius, with data collected during the first 2 min of running and each kilometer interval thereafter. Reductions in peak EMG of the pectoralis major, anterior and medial deltoid were reported when participants ran in the high breast support during the initial intervals of the run (up to the second kilometer). The increased activation in the pectoralis major, anterior and medial deltoid in the low breast support may be due to increased tension within these muscles, induced by the greater breast pain experienced in the low breast support. This may be a strategy to reduce the independent breast movement causing the pain through increased muscular activation. This study further promotes the use of a high breast support during running with potential benefits for treadmill running associated with reductions in muscular demand during a 5 km run.     

Effects of post-encoding wakeful rest and study time on long-term memory performance

Recent work shows that post-encoding wakeful rest, in contrast to a cognitive task delay period, supports memory performance. The present study aimed at investigating whether study time modulates the impact of post-encoding rest on delayed memory performance. Healthy young adults were allocated to one of two “study time” groups (fixed-paced vs. self-paced). Participants encoded two word lists. After immediate recall of one word list, participants wakefully rested for 8?min, after the other, they performed a visual problem solving task. A delayed recall took place at the end of the experimental session (Experiment 1) and again after 7 days (Experiment 1?+?2). We found that participants in the self-paced group outperformed those in the fixed-paced group. In Experiment 1, participants showed higher memory performances after 7 days in the resting condition independent of study time. No significant differences between post-encoding (rest vs. problem solving) and study time conditions were found in Experiment 2. Combined analyses of both experiments revealed that an additional recall (Experiment 1) supported memory retention in both post-encoding conditions. Our findings suggest that resting is beneficial over the long term, but only when the encoded information is repeatedly retrieved at the end of a learning session.     

Effects of motor programming on the power spectral density function of finger and wrist movements

Power spectral density analysis was applied to the frequency content of the acceleration signal of pen movements in line drawing. The relative power in frequency bands between 1 and 32 Hz was measured as a function of motoric and anatomic task demands. Results showed a decrease of power at the lower frequencies (1-4 Hz) of the spectrum and an increase in the middle (9-12 Hz), with increasing motor demands. These findings evidence the inhibition of visual control and the disinhibition of physiological tremor under conditions of increased programming demands. Adductive movements displayed less power than abductive movements in the lower end of the spectrum, with a simultaneous increase at the higher frequencies. The relevance of the method for the measurement of neuromotor noise as a possible origin of delays in motor behavior is discussed.     

Effects of scapular retraction/protraction position and scapular elevation on shoulder girdle muscle activity during glenohumeral abduction

According to scapulohumeral rhythm, shoulder abduction is followed through scapular upward rotation to ensure joint mobility and stability. Of interest, the shoulder abduction can be performed holding the scapula in different positions and in association with scapular elevation, with possible effects on shoulder muscle activity. Therefore, the aim of the study was to analyze the activity of relevant shoulder muscles and the activity ratios between the scapulothoracic muscles, during shoulder abduction performed in different combinations of scapular position (neutral, retracted, protracted) and scapular elevation.The electromyographic activity of middle deltoid, serratus anterior, upper, middle and lower fibers of trapezius was recorded during shoulder abduction movements executed holding the scapula in neutral, retracted and protracted position, and subsequently a shoulder elevation movement. The activation of each muscle and the scapulothoracic muscles activity ratios were determined every 15 degrees, from 15° to 120° of abduction.Scapular retraction led to higher activation of the entire trapezius muscle, whereas protraction induced higher upper trapezius, middle deltoid and serratus anterior activity, along with lower activity of middle and lower trapezius. Shoulder elevation led to higher activity of the upper trapezius and middle deltoid. Moreover, it induced lower activation of the serratus anterior and middle and lower trapezius, thus leading to high ratios between the upper trapezius and the other scapulothoracic muscles, especially between 15 and 75 degrees of abduction.This study highlights that shoulder abduction performed with scapular protraction and in combination with scapular elevation leads to increased activity of the middle deltoid and upper trapezius, resulting in imbalances between the scapulothoracic muscles that could hamper the optimal scapulohumeral rhythm. The abduction performed in the aforementioned scapular conditions also induce potential reciprocal inhibition effects between the movers and stabilizers muscles of scapula, suggesting different motor control strategies of integrating a common shoulder movement with various modification of the scapular position.     

Effect of reaction time condition on EMG activities of the biceps brachii muscle in elbow flexion and forearm supination

Under simple- and choice-RT conditions, the biceps brachii muscle was examined in 8 healthy male subjects to determine how the temporal and spatial characteristics of elbow flexion and forearm supination differed at the initial phase of EMG activity and whether preparation or the presence of response uncertainty influenced the EMG outputs of the two movements. In the simple-RT condition, RT of supination was significantly faster than that of flexion but EMG activity of supination was less than that of flexion. In contrast, in the choice-RT condition, RT of flexion was significantly faster than that of supination but EMG activity of flexion was significantly reduced compared to supination. These findings indicate that advanced preparation or motor set facilitates the differentiation of RTs and EMG activities of the response movements and that response uncertainty causes a significant change in the temporal and spatial specificity of both elbow flexion and forearm supination.     

Relationship between activity, rest, and free feeding in rats.

General activity and food intake were recorded concurrently in free-feeding rats. Correlations of meal size with associated postmeal interval, activity, and rest were determined. Meal size was significantly positively correlated with both the length of the postmeal interval and the amount of rest in the postmeal interval, but not with the amount of activity in the postmeal interval. This suggests that the amount of energy expended following a meal is not related to the initiation of the subsequent meal and that some alternate mechanism underlies meal-to-meal regulation.     

Effects of environmental support on overt and covert visuospatial rehearsal

People can rehearse to-be-remembered locations either overtly, using eye movements, or covertly, using only shifts of spatial attention. The present study examined whether the effectiveness of these two strategies depends on environmental support for rehearsal. In Experiment 1, when environmental support (i.e., the array of possible locations) was present and participants could engage in overt rehearsal during retention intervals, longer intervals resulted in larger spans, whereas in Experiment 2, when support was present but participants could only engage in covert rehearsal, longer intervals resulted in smaller spans. When environmental support was absent, however, longer retention intervals resulted in smaller memory spans regardless of which rehearsal strategies were available. In Experiment 3, analyses of participants’ eye movements revealed that the presence of support increased participants’ fixations of to-be-remembered target locations more than fixations of non-targets, and that this was associated with better memory performance. Further, although the total time fixating targets increased, individual target fixations were actually briefer. Taken together, the present findings suggest that in the presence of environmental support, overt rehearsal is more effective than covert rehearsal at maintaining to-be-remembered locations in working memory, and that having more time for overt rehearsal can actually increase visuospatial memory spans.     

Receiving and giving support: Effects on relationships and well-being

Sixty-five subjects reported amount of social support given and received, and satisfaction with relationships where support exchanges took place. Negative affect from relationships, psychological symptoms, and happiness were also measured. Multiple regression analyses showed that receiving and giving support was related to some negative feelings toward the relationships concerned. Receiving support was also related to inflated anxiety symptoms. Effects of receiving support on guilt and dependent feelings were moderated by relationship satisfaction. Effects of giving support on anxiety were also moderated by relationship satisfaction. Extraversion and satisfaction with relationships predicted happiness. There were some individual differences in support exchanges. Extraverts gave more support. Women received more support whereas conscientious people received less.     

Localization of electrocutaneous stimuli on the fingers and forearm: Effects of electrode configuration and body axis

Four experiments were done on the effects of electrode configuration (concentric vs. unifocal) and body axis (longitudinal vs. transverse) on localization of electrocutaneous pulse stimuli at the fingers and forearm. Subjects pointed to the apparent location of current pulses. For the transverse placement of electrodes, pulses were localized correctly, whatever the configuration and the body site might be. In addition, intrasubject variability at the forearm was smaller for the transverse axis than for the longitudinal axis. For the longitudinal placement of electrodes, pulses were localized as a function of configuration and body site. At the fingers, concentric electrodes provided precise localization but unifocal electrodes provided a great mislocalization; and intrasubject variability of localization was larger for the unifocal electrodes than for the concentric electrodes. At the forearm, whatever the configuration might be, the pulses were localized more proximally than the stimulus site; and intrasubject variability of localization did not differ between the configurations. These results are related to Boring’s anchor theory, apparent distance between two points, and the localization of other somatosensory stimuli.     

Effects of gender and gender role identification of participant and type of social support resource on support seeking

The relationship between type of social support resource (emotional vs. instrumental support) sought and gender and gender role identification was examined. Gender-typed and androgynous, white, middle to upper middle class males and females were given scenarios describing situations in which help was needed, and which also identified a female helper who would provide either emotional or instrumental support. The results indicated that males reported a significantly lower likelihood of seeking emotional support than instrumental support, while no significant differences were found between levels of seeking emotional and instrumental support for females. In comparing men and women for each type of support, it was found that males reported a significantly lower likelihood of seeking emotional support than did females. In addition, gender-typed males reported seeking emotional support significantly less than did the other three groups: androgynous males and females, and gender-typed females.This article was derived from the first author's master's thesis, who wishes to gratefully acknowledge the support and guidance of Ann Fuehrer, Richard Sherman, and Stephen Hinkle in the preparation of this article, the assistance of Andrew Avellano and Jami Pennington, and the anonymous reviewers for their comments on this article.     

Magnitude of cerebral asymmetry at rest: covariation with baseline cardiovascular activity

The cerebral regulation of cardiovascular functioning varies along both a lateral and a longitudinal axis. The parasympathetic and sympathetic nervous systems are lateralized to the left and right cerebral hemispheres, respectively. Further, the frontal lobes are known to be inhibitory in nature, whereas the temporal lobes are excitatory. However, no systematic investigation has been conducted to determine the nature and strength of the relationship between the left and right frontal and temporal lobes in regulating cardiovascular activity. The present investigation sought to examine these relationships by testing the hypothesis that negative correlations would be found between baseline heart rate and blood pressure and asymmetry of alpha magnitude across the frontal lobes. Further, positive correlations were hypothesized to exist across the temporal lobes. A total of 20 women were asked to relax with their eyes closed while heart rate and blood pressure as well as quantitative electroencephalography data were obtained. The results indicated that, as hypothesized, significant negative correlations existed across the frontal lobes and significant positive correlations existed across the temporal lobes. The results provide further support for a division of responsibility between the left and right frontal and temporal lobes in the regulation of heart rate and blood pressure.     

Influence of strategy on muscle activity during impact movements

Participants (N = 10) made flexions or extensions about the elbow. Movements either were pointing (i.e., self-terminated) or terminated by impact on a barrier. The author examined how the trajectory and the electromyographic (EMG) patterns varied according to the distance moved, the instruction provided concerning speed, or the type of termination. Variations in kinematics induced by changes in the target distance or the instruction regarding speed were the same for impact and pointing movements. In comparison with a pointing movement of similar distance and speed instruction, an impact movement (a) accelerated longer and reached a higher velocity, (b) had a longer agonist EMG burst, and (c) had a low level of contraction that started slightly after the agonist burst and continued throughout the movement but had little or no antagonist burst. Because the different types of movements required different forces from the muscles, there were systematic, task-specific differences in EMG patterns that reflected task-specific differences in central control. The results of this experiment demonstrate that impact movements share some of the rules used in the control of other tasks, such as pointing and reversing movements. The sharing is not imposed by mechanical or physiological constraints but, rather, represents the imposition of internal constraints.     

Effector dynamics of rhythmic wrist activity and its implications for (modeling) bimanual coordination

To examine the role of the effector dynamics of the wrist in the production of rhythmic motor activity, we estimated the phase shifts between the EMG and the task-related output for a rhythmic isometric torque production task and an oscillatory movement, and found a substantial difference (45-52 degrees) between the two. For both tasks, the relation between EMG and task-related output (torque or displacement) was adequately reproduced with a physiologically motivated musculoskeletal model. The model simulations demonstrated the importance of the contribution of passive structures to the overall dynamics and provided an account for the observed phase shifts in the dynamic task. Additional simulations of the musculoskeletal model with added load suggested that particular changes in the phase relation between EMG and movement may follow largely from the intrinsic muscle dynamics, rather than being the result of adaptations in the neural control of joint stiffness. The implications of these results are discussed in relation to (models of) interlimb coordination in rhythmic tasks.     

The inappropriate smile and zygomatic muscle activity

Long-term recording of activity of the zygomatic muscle, the most important mimic muscle involved in smiling, was performed in 22 disorganized type schizophrenic patients with inappropriate smiles and 15 normal subjects in two separate experiments. During inappropriate smiles, the zygomatic muscle exhibited waxing and waning bursts of activity with an amplitude of 75 to 120 microV, which could not be distinguished from the activity observed during usual smiling in normal subjects. However, the duration of such activity tended to be longer when compared to that in usual smiling by normal subjects as well as by schizophrenic patients. In contrast to usual smiles, inappropriate smiles decreased with personal contact. When asked about their thoughts during smiling shortly after inappropriate smiles, more patients reported that they thought of nothing at all or something not necessarily pleasant rather than something pleasant that would be expected to induce smiling.     

Covert neuromuscular activity of the dominant forearm during visualization of a motor task

This study evaluated specific covert neuromuscular activity during a silent visualization exercise. 30 subjects participated in a dual-baseline single-subject procedure. The experimental test condition required the subjects to visualize themselves squeezing a hand-size rubber ball as tightly as possible for 1 min. In the comparison test condition, subjects were asked to imagine the 'sun setting on the horizon' for 1 min. Visualization of the motor task brought about significant (p <.05) increases in dominant forearm EMG (microV) and heart-rate activity (bpm) from rest to the experimental test condition. Nondominant forearm activity showed no significant changes from rest to either test condition, and heart-rate activity (bpm) showed no significant change from rest to the comparison visualization task.