Walking kinematics and kinetics following eccentric exercise-induced muscle damage

The goal of this investigation was to investigate how walking patterns are affected following muscle-damaging exercise by quantifying both lower limb kinematics and kinetics. Fifteen young women conducted a maximal isokinetic eccentric exercise (EE) muscle damage protocol (5 × 15) of the knee extensors and flexors of both legs at 60°/s. Three-dimensional motion data and ground reaction forces (GRFs) were collected 24 h pre-EE while the participants walked at their preferred self-selected walking speed (SWS). Participants were asked to perform two gait conditions 48 h post-EE. The first condition (COND1) was to walk at their own speed and the second condition (COND2) to maintain the SWS (±5%) they had 24 h pre-EE. Walking speed during COND1 was significantly lower compared to pre-exercise values. When walking speed was controlled during COND2, significant effects of muscle damage were noticed, among other variables, for stride frequency, loading rate, lateral and vertical GRFs, as well as for specific knee kinematics and kinetics. These findings provide new insights into how walking patterns are adapted to compensate for the impaired function of the knee musculature following muscle damage. The importance to distinguish the findings caused by muscle damage from those exhibited in response to changes in stride frequency is highlighted.     

Bilateral eccentric and concentric torque of quadriceps and hamstring muscles in females and males

This study assessed maximum eccentric (ECC) and concentric (CON) torque of quadriceps (QUAD) and hamstring (HAM) muscle groups in healthy females (n = 13) and males (n = 27). Peak torques (PT) of bilateral muscle actions were recorded at constant angular velocities of 0.52, 1.57 and 2.61 rad.s-1. The QUADCON and HAMCON PT decreased (p less than 0.05) with increasing angular velocity. The QUADECC and HAMECC PT increased (p less than 0.05) in females, whereas QUADECC PT decreased (p less than 0.05) and HAMECC PT showed no change in males. In general, ECC PT was higher (p less than 0.05) than CON PT and QUAD PT was higher (p less than 0.05) than HAM PT, for any given angular velocity. Males displayed higher (p less than 0.05) PT than females but when PT were adjusted for body mass the sex differences in QUADCON and HAMCON were reduced (p less than 0.05), whereas the differences in QUADECC and HAMECC were abolished. The CON and ECC PT were, on average, 60% and 41% greater, respectively, in males than in females. The corresponding differences, when adjusted for body mass, were 23% and 8%. ECC:CON PT for QUAD were higher (p less than 0.05) in females than in males. CON and ECC HAM:QUAD PT ratio increased (p less than 0.05), as a function of velocity. This study suggests, that bilateral ECC PT is higher than CON PT and CON HAM:QUAD PT ratio is higher than ECC HAM:QUAD PT ratio.(ABSTRACT TRUNCATED AT 250 WORDS)     

Added mass in human swimmers: Age and gender differences

In unstationary swimming (changing velocity), some of the water around the swimmer is set in motion. This can be thought of as an added mass (M_a) of water. The purpose of this study was to find added mass on human swimmers and investigate the effect of shape and body size. Thirty subjects were connected to a 2.8 m long bar with handles, attached with springs (stiffness k=318 N/m) and a force cell. By oscillating this system vertically and registering the period of oscillations it was possible to find the added mass of the swimmer, given the known masses of the bar and swimmer. Relative added mass (M_a%) for boys, women and men were, respectively, 26.8±2.9%, 23.6±1.6% and 26.8±2.3% of the subjects total mass. This study reported significantly lower added mass (p<0.001) and relative added mass (p<0.002) for women compared to men, which indicate that the possible body shape differences between genders may be an important factor for determining added mass. Boys had significantly lower (p<0.001) added mass than men. When added mass was scaled for body size there were no significant differences (p=0.996) between boys and men, which indicated that body size is an important factor that influences added mass. The added mass in this study seems to be lower and within a smaller range than previously reported (Klauck, 1999, Eik et al., 2008). It is concluded that the added mass in human swimmers, in extended gliding position, is approximately 1/4 of the subjects’ body mass.     

Prevalence of metabolic syndrome and gender differences

In a comparative study, involving 500 subjects with 294 males and 206 females aged 30 years and above, data were collected from NIMS (National Institute of Medical Sciences) hospital and research centre and controls from the general population whose age and sex were matched with subjects during the years 2010 - 2011. Metabolic syndrome was present both in women and men corresponding to 29% and 23% of the women's and men's sample, respectively. The prevalence was higher in women than in men. In women, elevated BMI, low HDL cholesterol, increased waist circumference and hyperglycemia were significantly larger contributors to the metabolic syndrome while in men these were hypertension and elevated triglycerides. The contribution of several metabolic components to the metabolic syndrome is different in men and women. This might contribute to gender specific differences in the relative risk of metabolic complications such as insulin resistance.     

Hemodynamics of orthostatic intolerance: implications for gender differences

Women have a greater incidence of orthostatic intolerance than men. We hypothesized that this difference is related to hemodynamic effects on regulation of cardiac filling rather than to reduced responsiveness of vascular resistance during orthostatic stress. We constructed Frank-Starling curves from pulmonary capillary wedge pressure (PCWP), stroke volume (SV), and stroke index (SI) during lower body negative pressure (LBNP) and saline infusion in 10 healthy young women and 13 men. Orthostatic tolerance was determined by progressive LBNP to presyncope. LBNP tolerance was significantly lower in women than in men (626.8 +/- 55.0 vs. 927.7 +/- 53.0 mmHg x min, P < 0.01). Women had steeper maximal slopes of Starling curves than men whether expressed as SV (12.5 +/- 2.0 vs. 7.1 +/- 1.5 ml/mmHg, P < 0.05) or normalized as SI (6.31 +/- 0.8 vs. 4.29 +/- 0.6 ml.m-2.mmHg-1, P < 0.05). During progressive LBNP, PCWP dropped quickly at low levels, and reached a plateau at high levels of LBNP near presyncope in all subjects. SV was 35% and SI was 29% lower in women at presyncope (both P < 0.05). Coincident with the smaller SV, women had higher heart rates but similar mean arterial pressures compared with men at presyncope. Vascular resistance and plasma norepinephrine concentration were similar between genders. We conclude that lower orthostatic tolerance in women is associated with decreased cardiac filling rather than reduced responsiveness of vascular resistance during orthostatic challenges. Thus cardiac mechanics and Frank-Starling relationship may be important mechanisms underlying the gender difference in orthostatic tolerance.     

Age and gender differences in the relationship between heart rate reactivity and elevated serum lipids

Data on serum lipids and heart rate reactivity to a standardized mental arithmetic stressor were collected on 54 healthy men and 73 healthy women. Subjects' ages ranged from 18 to 61 years, allowing analysis of data from both young and older subgroups. MANOVA revealed that age was directly associated with elevated lipids in men and women. There was no significant relationship between reactivity and lipids for either older or young men. Conversely, young women showed a significant direct relationship between reactivity and Total Cholesterol and LDL, but this was not present for older women. Implications of these data for the previously reported hypothetical relationship between reactivity and lipids are discussed. Limitations of the study are examined, and future directions for research suggested.I wish to thank Dianne Vella for her assistance in aspects of data-collection. This research was supported by grant No. 900946 from the National Health & Medical Research Council.     

Specific and gender differences between hospitalized and out of hospital mortality due to myocardial infarction

In this paper, the authors evaluate gender related differences of myocardial infarction mortality before and after hospital admittance. Myocardial infarction mortality in the Clinical Hospital Split in the seven years period between 2000 and 2006, have been analyzed together with out of hospital sudden death patients with acute myocardial infarction established during autopsy. During the seven year period between 2000 and 2006, 3434 patients were treated for myocardial infarction in the Split Clinical Hospital, 2336 (68%) males and 1098 (32%) females with a 12% total mortality (427 patients). The annual number of hospitalized persons has been increasing during that period (474 in yr. 2000 us. 547 in yr. 2006), while mortality decreased from 15% in 2000 to 9.6% in 2006. Female patients had significantly higher hospital mortality than male patients, (228 or 21% vs. 202 or 9%, p<0.05). Women also had significantly higher total AMI mortality (23.7% vs. 15,7%, p <0.05). Anterior myocardial infarction with ST elevation in precordial leads had significantly higher mortality (19%) compared to patients with lateral (11%), inferior (10%) myocardial infarction with ST elevation and also NSTEMI (4%) mortality p<0.05. Female patients more frequently die in hospital, 84% (230) than out of hospital 16% (43). From the total number of AMI deaths (388) in male patients, 56% (217) were in hospital and 44% (171) out of hospital (p<0.001). Men had significantly higher prehospital mortality rate than women (81% vs. 19%, p<0.05). Men also more frequently died from ventricular fibrillation (22% vs. 10%, p<0.05), while women died more frequently of heart failure, cardiogenic shock, and myocardial rupture (33% vs. 15% p<0.05). Regarding the total number of deaths from myocardial infarction men had significantly higher prehospital mortality compared to women (178 or 7.3% vs. 43 or 3.7%, p<0.05). Anterior myocardial infarction had a significantly higher rate in patients dying pre-hospital (58%), in contrast to inferior (36%) and lateral myocardial infarction with ST elevation (6%) p<0.05. We have concluded that male patients die more frequently within the first few hours of AMI mostly due to malignant arrhythmias, while female patients died in sub acute stage due to heart failure while being hospitalized. Nevertheless total mortality of AMI remains significantly higher in women.     

Shoulder and hip roll differences between breathing and non-breathing conditions in front crawl swimming

The effects of breathing on body roll have been previously investigated for the roll of the whole trunk only. The purposes of this study were: to calculate separately the shoulder roll (SR) and hip roll (HR) of swimmers during front crawl for non-breathing and preferred-side breathing conditions; to assess the differences in the magnitude and temporal characteristics of these variables between non-breathing and preferred-side breathing conditions; and to examine their association with swimming performance (indicated by swimming speed). Twelve male swimmers who competed at national and international level performed two maximum 25 m front crawl trials: one non-breathing and one with breathing to their preferred side. Performance was recorded with four below and two above water synchronised cameras. SR and HR in both trials were calculated for the breathing and non-breathing sides. The timings of SR and HR peaks to each side and at the positions of neutral roll were also calculated. Swimming speed was significantly slower in the breathing trial (p < 0.01). Swimmers rolled their shoulders and hips to the breathing side significantly more in the breathing than in the non-breathing trial (SR: p < 0.01; HR: p = 0.03). Nevertheless, there were no significant differences in the overall SR or HR between these trials. In the breathing trial, SR was higher in the breathing than in the non-breathing side (p < 0.01) but HR was not significantly different (p = 0.07). There was no evidence to suggest that temporal characteristics of SR or HR were associated with swimming performance.     

Odor-evoked autobiographical memories: age and gender differences along the life span

Odors are powerful in bringing back old and vivid memories bearing emotional content. This inherent hedonic property of olfactory stimuli makes this sensory modality particularly suitable for studying autobiographical memory. In the present work, adolescents (first experiment), young adults (second experiment), and elderly (third experiment) of both sexes were asked to smell 10 familiar odorants and to report if these odorants evoked personal autobiographical memories or referential memories (i.e., names and objects). The participants were then required to link these memories to triplets of words using the progressive elaboration method of the Loci mnemonic. The aim of the study was to investigate whether 1) odorants evoking autobiographical memories led to faster reaction times (RTs) and to a greater number of correct responses in the recall of the items associated to such memories than do odorants evoking referential memories, 2) females differed from males on the above tasks along with the life span, and 3) the preferential codes (i.e., autobiographical or referential) attributed to the odorants vary according to gender and age. In general, it was observed that the way in which the odorants were encoded affected the subsequent retrieval. Indeed, data analyses have shown that odorants evoking autobiographical memories lead to faster RTs (experiments 2 and 3) and that females outperform males (experiments 1 and 2). However, these effects are greatly age and gender dependent. Furthermore, females are more prone than males to code the odorants autobiographically (as shown by the higher amount of autobiographical experiences that they have provided at all ages relative to males). Results are discussed in terms of developmental differences and odor-emotion links and the possible role of odors and autobiographical memory in learning and retrieval of other items.     

Effects of gender and foot-landing techniques on lower extremity kinematics during drop-jump landings

The purpose of this study was to assess kinematic lower extremity motion patterns (hip flexion, knee flexion, knee valgus, and ankle dorsiflexion) during various foot-landing techniques (self-preferred, forefoot, and rear foot) between genders. 3-D kinematics were collected on 50 (25 male and 25 female) college-age recreational athletes selected from a sample of convenience. Separate repeated-measures ANOVAs were used to analyze each variable at three time instants (initial contact, peak vertical ground reaction force, and maximum knee flexion angle). There were no significant differences found between genders at the three instants for each variable. At initial contact, the forefoot technique (35.79 degrees +/- 11.78 degrees ) resulted in significantly (p = .001) less hip flexion than did the self-preferred (41.25 degrees +/- 12.89 degrees ) and rear foot (43.15 degrees +/- 11.77 degrees ) techniques. At peak vertical ground reaction force, the rear foot technique (26.77 degrees +/- 9.49 degrees ) presented significantly lower (p = .001) knee flexion angles as compared with forefoot (58.77 degrees +/- 20.00 degrees ) and self-preferred (54.21 degrees +/- 23.78 degrees ) techniques. A significant difference for knee valgus angles (p = .001) was also found between landing techniques at peak vertical ground reaction force. The self-preferred (4.12 degrees +/- 7.51 degrees ) and forefoot (4.97 degrees +/- 7.90 degrees ) techniques presented greater knee varus angles as compared with the rear foot technique (0.08 degrees +/- 6.52 degrees ). The rear foot technique created more ankle dorsiflexion and less knee flexion than did the other techniques. The lack of gender differences can mean that lower extremity injuries (e.g., ACL tears) may not be related solely to gender but may instead be associated with the landing technique used and, consequently, the way each individual absorbs jump-landing energy.     

Age distribution and gender differences in psychogenic fever patients

Psychogenic fever is one of the most common psychosomatic diseases. In Japan, psychogenic fever has generally been reported to occur in adolescents, with a peak seen at age 13. However, in our department we have encountered many adults with psychogenic fever. Therefore, we investigated all outpatients who visited the Psychosomatic Department of the University of Occupational and Environmental Health between April 2003 and March 2007. Of the 2705 outpatients that were seen, 55 patients (2.0%) were diagnosed with psychogenic fever. The patients ranged in age from 11 to 82 years old, with a mean age of 33.6 ± 17.9 (mean ± SD) years. In addition to the adolescents, many of the patients were in their 20 s and 30 s, and the male:female ratio was 1:2.2. This study suggests that psychogenic fever commonly occurs not only in adolescents but also in adults.     

The influence of hip strength on gluteal activity and lower extremity kinematics

The effects of hip muscle strength and activation on anterior cruciate ligament injury biomechanics, particularly knee valgus loading, have been reported in isolation and with equivocal results. However, the combination of these factors influences joint biomechanics. This investigation evaluated the influence of hip strength on gluteal activation and knee valgus motion. Maximal isometric hip abduction (ABD) and external rotation (ER) contractions were used to define High and Low strength groups. Knee kinematics and gluteus maximus (GMax) and medius (GMed) EMG amplitudes obtained during landing were compared between High and Low strength groups after controlling for the potential confounding influence of sex. Knee valgus motion did not differ between the High and Low hip ABD and ER strength groups. However, the Low ABD and ER strength groups displayed greater GMed and GMax EMG amplitudes, respectively, compared to the High strength groups. These findings suggest that weaker individuals compensate for a lack of force production via heightened neural drive. As such, hip muscle strength influences knee valgus motion indirectly by determining neural drive requirements.     

Relationship between hip and knee strength and knee valgus during a single leg squat

The purpose of this study was to determine the relationship between hip and knee strength, and valgus knee motion during a single leg squat. Thirty healthy adults (15 men, 15 women) stood on their preferred foot, squatted to approximately 60 deg of knee flexion, and returned to the standing position. Frontal plane knee motion was evaluated using 3-D motion analysis. During Session 2, isokinetic (60 deg/sec) concentric and eccentric hip (abduction/adduction, flexion/extension, and internal/external rotation) and knee (flexion/extension) strength was evaluated. The results demonstrated that hip abduction (r2=0.13), knee flexion (r2=0.18), and knee extension (r2=0.14) peak torque were significant predictors of frontal plane knee motion. Significant negative correlations showed that individuals with greater hip abduction (r=-0.37), knee flexion (r=-0.43), and knee extension (r=-0.37) peak torque exhibited less motion toward the valgus direction. Men exhibited significantly greater absolute peak torque for all motions, excluding eccentric internal rotation. When normalized to body mass, men demonstrated significantly greater strength than women for concentric hip adduction and flexion, knee flexion and extension, and eccentric hip extension. The major findings demonstrate a significant role of hip muscle strength in the control of frontal plane knee motion.