Dominance of gait cycle duration in casual walking

In gait research, casual walking has been considered to be walking at a casual speed. However, it is unclear that walking speed is the most stable factor in casual walking compared to other factors such as cycle duration and stride length. Although walking speed can be calculated from cycle duration and stride length, it is not necessarily the case that these parameters are "stable" in the same manner. We therefore conducted an experiment to determine which of these three parameters is most stable, regarding walking speed as cycle speed and using the coefficient of variation across gait cycles as index of stability. Ten participants were invited to walk in their own casual manner, once a week for a period of four weeks. Cycle duration was measured by means of a foot switch attached to the right heel. To measure the moving distance, participants towed a distance meter. Stride length and cycle speed were measured using this device. Over the four-week period, cycle duration and stride length were stable, whereas cycle speed was the most variable parameter. Furthermore, in the results for each single day, the cycle duration was significantly more stable than the other parameters. These results suggest that, when we walk casually, cycle duration is the dominant factor, rather than stride length or walking speed.     

Pain perception across the menstrual cycle phases in women with chronic pain

The menstrual cycle has been reported to alter pain perception but the patterns differ among studies. It has been reported that estrogens may influence somatic sensory processes. The present aim was to investigate whether the perception of pain varies by phases of the menstrual cycle. 20 women with chronic low pain volunteered to participate and were asked to rate their pain each day during three successive menstrual cycles. The menstrual cycle was divided into four and five phases to be able to compare results. Analysis showed there were phase differences in pain ratings during the menstrual cycle. Regardless of whether the menstrual cycle was divided into four or five phases, women rated pain significantly higher in the menstrual and premenstrual phases than in the midmenstrual and ovulatory phases. This is consistent with other studies showing less pain sensitivity during phases of the menstrual cycle associated with high estrogen. Women with high pain frequency reported more frequently a passive coping style and catastrophizing thoughts.     

MOOD FLUCTUATIONS

Mood fluctuations in women and men were studied both prospectively and retrospectively to determine whether cyclic changes occur over phases of the menstrual cycle, lunar cycle, and/or days of the week. The participants (15 women using oral contraceptives, 12 normally cycling women, and 15 men), who did not know the purpose of the study, recorded the pleasantness, arousal, and stability of their moods daily for 70 days (concurrent data). Later they recalled (retrospective data) their average mood for each day of the week and phase of the menstrual cycle (women only). The only evidence of mood fluctuation over the menstrual cycle in the concurrent reports was that normally cycling women reported more pleasant moods in the follicular and menstrual phase than did men and women on oral contraceptives. Women's moods fluctuated less over the menstrual cycle than over days of the week. Recollections of menstrual mood changes differed from actual changes: Women recalled more pleasant moods in the follicular phase and more unpleasant moods in the premenstrual and menstrual phases than they had reported concurrently. Bias also was evident in recollections of weekday mood fluctuations: Weekend highs were exaggerated and Monday blues were reported even though they were not reported concurrently. There was no evidence of mood fluctuations over the lunar cycle and the groups did not differ in mood stability. The retrospective reporting bias for both the mensural cycle and days of week suggests the influence of stereotypes about moods. Implications for research and practice are discussed.     

Influence of duty cycle and off time of comparison-tone pulse trains on the measurement of perstimulatory loudness adaptation

An experiment was conducted to determine if duty cycle and off time of tone pulses presented to the comparison ear influence adaptation measured at the opposite (test) ear. Eight subjects were adapted for 5 min to a 1-kHz pure tone at 60 dB SPL. Using a tracking procedure, adaptation was measured under five comparison-signal conditions, each comprised of 1-kHz pulse trains having different on/off times. The on/off times (in milliseconds) were: 200/800 (20% duty cycle); 500/500, 200/200, and 800/800 (50% duty cycle); and 800/200 (80% duty cycle). Adaptation was found to increase as the duty cycle of the comparison tones increased from 20% to 80%. This was evident even when attempts were made to account for the extent to which pulse trains are perceived as softer than continuous signals at the same level (the so-called LOT effect). For the 50%-duty-cycle conditions, similar amounts of adaptation were measured whether the on/off times of the signals were 200, 500, or 800 msec.     

Visual cerebral lateralization over phases of the menstrual cycle: a preliminary investigation

This study investigated whether visual cerebral asymmetries would change in phase with hormonal variations during the menstrual cycle. Lexical decision and line orientation tasks were administered during follicular, luteal, and menstrual phases of each woman's cycle. These tasks were also administered to a reference group of male subjects. Signal detection analyses indicated an unvarying RVF advantage in word/nonword discriminability (d') throughout the menstrual cycle, but a phase-dependent shift in left hemisphere response criterion (log beta). Gender differences were present for discriminability of line orientation, and female performance on this task varied over the cycle. The results imply that the neural systems subserving some cognitive functions are sensitive to fluctuations in gonadal steroids and suggest a hormonal basis for gender differences in some visual-spatial functions.     

Phase of oral contraceptive cycle and endurance capacity of rowers

Eight female rowers (M age = 21.0 yr., SD = 2.8), using a monophasic oral-contraceptive pill, performed a 1-hr. rowing ergometer test (intensity: 70% VO2max) during the active-pill and non active-pill phases of the oral contraceptive cycle. No significant differences were found in mean energy expenditure, oxygen consumption, respiratory exchange ratio, and heart rate during the endurance test at the two phases of the oral contraceptive cycle. Mean energy expenditure rate, carbohydrate energy expenditure, lipid energy expenditure, and blood lactate during the test were not statistically significantly different among the cycle phases. In conclusion, there was no observed difference in substrate oxidation and blood lactate level during endurance rowing at different phases of the oral contraceptive cycle in these endurance-trained rowers. Endurance-trained female athletes on oral contraceptives should not worry about the possible differences in substrate oxidation during everyday training at different phases of the oral contraceptive cycle.     

Differential effects of the menstrual cycle on reactive and proactive aggression in borderline personality disorder

Borderline personality disorder (BPD) is characterized by rapidly shifting symptoms, including intense anger and aggressive behavior. Understanding how fluctuations in ovarian hormones across the menstrual cycle may contribute to symptom instability is key for accurate assessment of BPD symptoms and effective interventions. Reactive and proactive aggression, as well as anger-in and anger-out, were assessed daily in 15 physically healthy, unmedicated naturally cycling female individuals meeting criteria for BPD across 35 days. Urine luteinizing hormone surge and salivary progesterone were used to confirm ovulation and verify the cycle phase. Multilevel models evaluated cyclical differences of symptoms between cycle phases. Both forms of aggressive behavior demonstrated marked cycle effects, with reactive aggression highest during the midluteal cycle phase, co-occurring with initial increases in anger and irritability and followed by perimenstrual peaks in anger and anger-in. In contrast, highest levels of proactive aggression were observed during the follicular and ovulatory phases, when emotional symptoms and anger were otherwise at lowest levels. These findings highlight the importance of identifying the function of aggression when considering potential psychological and biological influences. Naturally cycling individuals with BPD may be at elevated risk for luteal worsening of a range of interpersonally reactive symptoms, including reactive aggression, whereas proactive aggression may occur more in phases characterized by less emotional and cognitive vulnerability and greater reward sensitivity. Research on aggression in this population should consider cycle effects. Cycling individuals with BPD attempting to reduce aggressive behavior may benefit from cycle-tracking to increase awareness of these effects and to develop appropriate strategies.     

Effects of menstrual cycle phase on aggression measured in the laboratory

This study investigated the effects of menstrual cycle phase on aggression in two groups of women, which differed in the severity of their self-reported perimenstrual symptoms. A low- and a high-symptom group were recruited using the Menstrual Distress Questionnaire (MDQ) to define the groups. Twenty-two subjects (11 low and 11 high symptom) participated across one menstrual cycle: during the premenstrual, menstrual, midfollicular, and ovulatory phases. The Point Subtraction Aggression Paradigm was used to assess aggression on each day of participation. There were three main findings; a) rates of aggressive responding did not vary across phases of the menstrual cycle; b) the high-symptom group emitted higher rates of aggressive responding across the menstrual cycle than did the low-symptom group; and c) rates of aggressive responding correlated with the MDQ's behavioral and psychological scales and not the somatic scales. These findings indicate that the menstrual cycle phase does not differentially affect this laboratory measure of aggression. The differences found between the two symptom groups parallel a few reports indicating that women who differ in retrospectively reported mood and behavioral changes related to their menstrual cycle also differ on a number of other psychometric measures. Aggr. Behav. 24:9–26, 1998. © 1998 Wiley-Liss, Inc.     

Evidence for generalized motor programs using gait pattern analysis

Human intra limb gait kinematics were analyzed via statistical and structural pattern recognition methods to determine the role of relative timing of limb segments within and between modes of gait. Five experienced runners were filmed while walking (3-6 km/hour) and running (8-12 km/hour) on a motor driven treadmill. Kinematic data consisted of relative timing of the four phases of the Philippson step cycle and intersegmental limb trajectories, determined from angle-angle diagrams. Despite marked decreases in absolute time durations within gaits remained constant over the speeds which were studied. Although a 2-fold increase in locomotor speed occurred in walking and a 1.5-fold speed increase occurred within running, the percentage of time spent in each of the Philippson phases was not significantly changed. However, significant differences in the time percentages and sequences of the step cycle phases were found between walking and running. Correlations between limb segment trajectories occurring in the different gaits showed strong coherence for overall step cycle patterns, but within step cycle phases and across speeds, selective phases displayed little correspondence.     

Menstrual cycle as focus of study and self-reports of moods and behaviors

Retrospective questionnaires show cyclical variations in moods and behaviors across the menstrual cycle. However, results obtained from daily mood questionnaires are inconsistent. In the present study, which ran for 11 weeks, self-report measures of menstrual symptomatology, using the 8-factor Moos (1968, 1969 a,c) Menstrual Distress Questionnaire (MDQ), were investigated. The MDQ was administered under conditions that made the menstrual cycle a salient (retrospective questionnaire) or not a salient (daily questionnaire) part of the study. The study included women who were taking and not taking oral contraceptives. A 2×3 analysis of variance (with the two groups of women and three menstrual cycle phases as independent variables) yielded broad cyclical variations only in the menstrual cycle salient condition. When the menstrual cycle was not a salient part of the study, only the pain factor reached significant cyclical variation (p<.01).A 2×3 analysis of variance (with the two types of questionnaires and three menstrual cycle phases as independent variables) indicated that for women not taking oral contraceptives the two questionnaires differed on pain (p<.01), concentration (p<.01), autonomic reaction (p<.05), and water retention (p<.01). Phase effects were significant on all factors, with largest cyclical variations in the menstrual cycle salient condition. A similar analysis for women taking oral contraceptives yielded fewer significant differences. These results suggest that questionnaires that make the menstrual cycle a salient part of the study may exaggerate possible cyclical variations in moods and behaviors.The authors are grateful to Dawn Christie Burns and Ross Hodges for their help in data reduction.     

Hormones and dichotic listening: evidence from the study of menstrual cycle effects

This report presents evidence for changes in dichotic listening asymmetries across the menstrual cycle, which replicate studies from our laboratory and others. Increases in the right ear advantage (REA) were present in women at phases of the menstrual cycle associated with higher levels of ovarian hormones. The data also revealed correlations between hormone levels and behavioural measures of asymmetry. For example, the pre-ovulatory surge in luteinising hormone (LH) was related to a decrease in left ear scores, which comprised a key part of the cycle related shift in asymmetry. Further analysis revealed a subgroup of women who had not reached postovulatory status by days 18-25 of the cycle, as verified by low progesterone levels. These women showed laterality profiles at days 18-25 that looked more like the other women when measured at the periovulatory phase (i.e., days 8-11). Data were combined with those from a previous study to highlight the stability of effects. Results showed a distinct menstrual cycle related increase in asymmetry in the combined sample. This final comparison confirmed the nature of sex differences in dichotic listening as being dependent on hormone status in women.     

Against Relative Timing Invariance in Movement Kinematics

The kinematics of stair climbing were examined to test the assertion that relative timing is an invariant feature of human gait. Six male and four female subjects were video-recorded (at 60 Hz) while they climbed a flight of stairs 10 times at each of three speeds. Each gait cycle was divided into three segments by the maximum and minimum angular displacement of the left knee and left foot contact. Gentner's (1987) analysis methods were applied to the individual subject data to determine whether the duration of the segments remained a fixed proportion of gait cycle duration across changes in stair-climbing speed. A similar analysis was performed using knee velocity maxima to partition the gait cycle. Regardless of how the gait cycle was divided, relative timing was not found to remain strictly invariant across changes in speed. This conclusion is contrary to previous studies of relative timing that involved less conservative analysis but is consistent with the wider gait literature. Strict invariant relative timing may not be a fundamental feature of movement kinematics.     

Coordination of the upper and lower extremities

Simultaneous walking and hand clapping were utilized to examine the patterns of coordination between upper and lower limbs. Eighteen normal adult subjects were filmed at high speed under instructions to: (a) walk and clap at a self-determined “preferred” speed, (b) walk as fast as possible while clapping at the preferred speed, (c) walk at the preferred speed while clapping as fast as possible and (d) walk and clap as fast as possible. Temporal data and individual patterns of phase relations were analyzed. Results indicated a disruption of the preferred clap cycle when combine with fast walking. The degree of disruption was a function of the individual coordinative pattern at the preferred rate. It is concluded that: (a) the temporal patterning of the clap cycle can be dictated by the step cycle, (b) heel strike is the point about which the clap cycle is modulated, and (c) subjects can select from various modes of phase linkage.     

Content-specific activational effects of estrogen on working memory performance

The authors explored the influence of task content and the menstrual cycle phase on working memory (WM) performance. They addressed the content specificity of WM in the framework of evolutionary psychology, proposing a hormone-mediated adaptive design governing face perception. The authors tested 2 groups of healthy young women (n = 66 women with regular menstrual cycle, n = 27 oral contraceptive users) on a WM task with adult male or infant face photographs. Analyses of variance showed significant interaction between task content and estrogen level. Women were more efficient in solving the male faces task during high-estrogen phase of the cycle than during low-estrogen phase. No differences were found in the efficacy of solving the infant faces task between different phases of the cycle. Results suggest content-specific activational effects of estrogen on the WM performance and are consistent with the notion of a hormonal mechanism underlying adaptive shifts in cognition related to mating motivation.     

Physical Characteristics of the Menstrual Cycle and Premenstrual Depressive Symptoms

ABSTRACT— Little is known about the associations between premenstrual depressive symptoms and specific physical symptoms of the menstrual cycle. In a nonclinical sample of 183 female university students, six physical symptoms of the menstrual cycle (headaches, skin changes, gastrointestinal problems, breast changes, and coagulation and heaviness of menstrual bleeding) were tested for their associations with premenstrual depressive symptoms. The physical symptoms explained nearly 30% of the variance in depressive symptoms. Moreover, when the summed score for all six physical symptoms was used as a predictor of depressive symptoms, a strong linear effect and a moderate curvilinear effect were observed. These results could not be explained by response bias or by the presence of a small group of highly depressed individuals. This study emphasizes the need to consider physical symptoms of the menstrual cycle to better understand premenstrual depressive symptoms, and suggests that the contribution of the menstrual cycle to depressive symptoms in the general population is underrecognized.     

Response-dependent shock in second-order fixed-ratio schedules of food presentation

Three pigeons key pecked under second-order schedules in which the completion of two successive fixed-ratio 50 components constituted a reinforcement cycle. Tandem, chained, and brief-stimulus second-order schedules were studied when completion of the initial fixed-ratio 50 component delivered brief intense electric shock in every nth reinforcement cycle and n assumed values between one and nine. During sessions without shock, the brief-stimulus (unpaired with food) schedule generated higher rates of responding in the initial component than did the tandem schedule. Electric shock engendered increased time to the fifth response and a repeated pause-run pattern of not responding and responding, particuuarly in the initial component, even with shock scheduled in every ninth reinforcement cycle. The results were consistent with those reported for shock of a shorter duration scheduled in every reinforcement cycle. The overall rate of responding decreased as a function of increasing shock density and was lower in brief-stimulus than in tandem schedules.     

Stability of harassment in children: analysis of the Canadian National Longitudinal Survey of Children and Youth data

No longitudinal information about bullying and peer harassment among Canadian children currently exists. In the present study, the author examined the stability of bullying and harassment. The sample consisted of two cohorts of children aged 10-11 years (n=2798) and 12-13 years (n=1946) drawn from the Canadian National Longitudinal Survey of Children and Youth, which is a stratified random sample of households in Canada. The author analyzed children's reports of bullying and harassment from 1994 to 2001 using cross-sectional time-series analyses. The results show that children who were not bullied or harassed in one cycle were unlikely to report being bullied or harassed at a subsequent cycle. About half of children who reported being bullied or harassed in a previous cycle also reported being bullied or harassed in a subsequent cycle. The author concludes that some children may be resilient, whereas others are vulnerable to ongoing bullying and harassment from their peers.     

Calories,beauty, and ovulation: The effects of the menstrual cycle on food and appearance-related consumption

The menstrual cycle has been largely ignored within the consumer research literature. Using a survey panel, women's food and appearance-related consumption was tracked for 35 consecutive days. As predicted, food-related desires, dollars spent, and eating behaviors were greater during the luteal (non-fertile) phase, whereas appearance-related desires, dollars spent, and beautification behaviors increased during the fertile phase. Dollars spent on products unrelated to food or beautification were not significantly influenced by the menstrual cycle. Hence, women's consumption desires, preferences, and dollars spent in evolutionarily relevant product categories (food and mating) fluctuate across their ovulatory cycle. Branding-related implications are briefly discussed.     

The circle of life: A cross‐cultural comparison of children's attribution of life‐cycle traits

Do children attribute mortality and other life‐cycle traits to all minded beings? The present study examined whether culture influences young children's ability to conceptualize and differentiate human beings from supernatural beings (such as God) in terms of life‐cycle traits. Three‐to‐5‐year‐old Israeli and British children were questioned whether their mother, a friend, and God would be subject to various life‐cycle processes: Birth, death, ageing, existence/longevity, and parentage. Children did not anthropomorphize but differentiated among human and supernatural beings, attributing life‐cycle traits to humans, but not to God. Although 3‐year‐olds differentiated significantly among agents, 5‐year‐olds attributed correct life‐cycle traits more consistently than younger children. The results also indicated some cross‐cultural variation in these attributions. Implications for biological conceptual development are discussed.