Role of sex and stature on the biomechanics of normal and loaded walking: implications for injury risk in the military.

Load carriage and marching 'in-step' are routine military activities associated with lower limb injury risk in service personnel. The fixed pace and stride length of marching typically vary from the preferred walking gait and may result in overstriding. Overstriding increases ground reaction forces and muscle forces. Women are more likely to overstride than men due to their shorter stature. These biomechanical responses to overstriding may be most pronounced when marching close to the preferred walk-to-run transition speed. Load carriage also affects walking gait and increases ground reaction forces, joint moments and the demands on the muscles. Few studies have examined the effects of sex and stature on the biomechanics of marching and load carriage; this evidence is required to inform injury prevention strategies, particularly with the full integration of women in some defence forces. This narrative review explores the effects of sex and stature on the biomechanics of unloaded and loaded marching at a fixed pace and evaluates the implications for injury risk. The knowledge gaps in the literature, and distinct lack of studies on women, are highlighted, and areas that need more research to support evidence-based injury prevention measures, especially for women in arduous military roles, are identified.

A novel and simple test of gait adaptability predicts gold standard measures of functional mobility in stroke survivors.

BACKGROUND: Although there is evidence that stroke survivors have reduced gait adaptability, the underlying mechanisms and the relationship to functional recovery are largely unknown. We explored the relationships between walking adaptability and clinical measures of balance, motor recovery and functional ability in stroke survivors. METHODS: Stroke survivors (n=42) stepped to targets, on a 6m walkway, placed to elicit step lengthening, shortening and narrowing on paretic and non-paretic sides. The number of targets missed during six walks and target stepping speed was recorded. Fugl-Meyer (FM), Berg Balance Scale (BBS), self-selected walking speed (SWWS) and single support (SS) and step length (SL) symmetry (using GaitRite when not walking to targets) were also assessed. Stepwise multiple-linear regression was used to model the relationships between: total targets missed, number missed with paretic and non-paretic legs, target stepping speed, and each clinical measure. RESULTS: Regression revealed a significant model for each outcome variable that included only one independent variable. Targets missed by the paretic limb, was a significant predictor of FM (F(1,40)=6.54, p=0.014,). Speed of target stepping was a significant predictor of each of BBS (F(1,40)=26.36, p<0.0001), SSWS (F(1,40)=37.00, p<0.0001). No variables were significant predictors of SL or SS asymmetry. DISCUSSION: Speed of target stepping was significantly predictive of BBS and SSWS and paretic targets missed predicted FM, suggesting that fast target stepping requires good balance and accurate stepping demands good paretic leg function. The relationships between these parameters indicate gait adaptability is a clinically meaningful target for measurement and treatment of functionally adaptive walking ability in stroke survivors.

Effects of dual task on turning ability in stroke survivors and older adults.

BACKGROUND: Turning is an integral component of independent mobility in which stroke survivors frequently fall. OBJECTIVE: This study sought to measure the effects of competing cognitive demands on the stepping patterns of stroke survivors, compared to healthy age-match adults, during turning as a putative mechanism for falls. METHODS: Walking and turning (90°) was assessed under single (walking and turning alone) and dual task (subtracting serial 3s while walking and turning) conditions using an electronic, pressure-sensitive walkway. Dependent measures were time to turn, variability in time to turn, step length, step width and single support time during three steps of the turn. Turning ability in single and dual task conditions was compared between stroke survivors (n=17, mean ± SD: 59 ± 113 months post-stroke, 64 ± 10 years of age) and age-matched healthy counterparts (n=15). RESULTS: Both groups took longer, were more variable, tended to widen the second step and, crucially, increased single support time on the inside leg of the turn while turning and distracted. CONCLUSIONS: Increased single support time during turning may represent biomechanical mechanism, within stepping patterns of turning under distraction, for increased risk of falls for both stroke survivors and older adults.

Work experience program at a metropolitan paediatric hospital: assisting rural and metropolitan allied health professionals exchange clinical skills.

The needs of rural allied health professionals (AHPs) have been widely documented. In particular, problems of professional isolation, lack of professional development opportunities and limited support systems have been highlighted as problems associated with working in rural and remote areas. This research aimed to provide rural and remote AHPs with an opportunity to gain experience in paediatric clinical areas of their choice, to provide rural/remote and metropolitan AHPs with an opportunity to share clinical knowledge and expertise, and to develop networks between rural/remote and metropolitan AHPs. A clinical experience program was developed to meet these aims. Twenty-nine AHPs from rural and remote areas of Queensland participated in the program. Participants completed questionnaires at the end of clinical experience program and 4-8 weeks after the visit. A focus group was also conducted. Analyses found the program met the majority of participants goals and expectations. Enhanced clinical skills in specialist paediatric areas, increased networking and access to resources were reported by rural/remote AHPs as benefits of the program. The role of a clinical consultant was found to be critical to the success of the program.

Divergent selection for incidence of degenerative myopathy of the Musculus supracoracoideus of meat-type chickens.

The response to three generations of selection for incidence of degenerative myopathy of the Musculus supracoracoideus (DMS) in meat-type chickens was studied. From each of two genetic bases named E and F, which were derived from two commercial broiler stocks, a high incidence, low incidence, and a nonselected control strain were initiated. Selection of breeders to produce Generations 1 and 2 was based on the incidence of DMS in their parents after induced wing exercise; mass selection for plasma creatine kinase levels after induced wing exercise was used to produce Generation 3. Little genetic progress in selection occurred in Generations 1 and 2. There was a response in Generation 3, especially in Base E selected for low incidence. Heritability of incidence of DMS was estimated to be .48. Body weights at 8 weeks of age, 18 weeks of age, and breast angle at 18 weeks of age of Generation 3 were greater (P less than .05) for affected than nonaffected birds and positively correlated phenotypically with incidence of DMS. Genetic correlations were extremely variable. The higher incidence of DMS in birds with desirable traits suggests that the breeder must use a multitrait selection program to reduce incidence of DMS as well as improve production traits.

Degenerative myopathy of the Musculus supracoracoideus and production traits in strains of meat-type chickens.

The incidence of degenerative myopathy of the Musculus supracoracoideus (DMS) was calculated in 23 strains comprising 1868 meat-type chickens. Twenty strains were commercial parent stocks and three strains were experimental strains from Ottawa similar to commercial broiler stocks of some 15 to 20 years ago. In the commercial strains DMS incidence ranged from 0 to 43% in males and 0 to 22% in females at ages ranging from 49 to 68 weeks. The three experimental strains did not have DMS. Data from strains with DMS were analyzed for associations between DMS and each of a number of body size and egg production traits. The DMS-positive birds had a larger breast angle (P less than .05) measured at 6 weeks of age (93 vs. 89 degrees) and a larger body weight (P less than .01) at 52 weeks (3748 vs 3594 g) than DMS-free birds. No significant relationships with other body size or egg production traits were detected.

Response to five generations of selection for blood cholesterol levels in White Leghorns.

The response to five generations of selection for high and low plasma cholesterol levels was examined in two lines of Single Comb White Leghorn chickens derived from the same population. An unselected control line was also maintained. Juvenile cholesterol levels of blood plasma were measured in 24,754 birds during the experiment. Males at 9 to 10 weeks of age had higher plasma cholesterol levels than females of the same age. Estimates of the heritability of plasma cholesterol level for males and females from the sire and dam components of variance in unselected population, ranged from .19 to .30. Realized heritabilities from the selected lines were lower and ranged from .14 to .19 with no significant differences between lines or sexes. Differences between the two selected lines in the fifth generation were 37 mg% for males and 33 mg % for females. High cholesterol levels were associated with high mortality. The estimated genetic correlation between plasma cholesterol and egg production was negative. After five generations of selection for plasma cholesterol, yolk cholesterol was 108 mg % lower in the low selected line than in the controls, but there was little difference between the high selected line and controls in this trait.

Plasma creatine kinase as an indicator of degenerative myopathy in live turkeys.

1. Diagnosis for degenerative myopathy of the Musculus supracoracoideus (DMS) in the live bird was attempted from plasma creatine kinase (CK) [EC 2.7.3.2] activities in 70 female turkeys. The blood of each bird was sampled 18 to 20 times over an age span of 16 to 79 weeks. 2. DMS incidence was 15.7%. 3. After CK values were logarithmically transformed and corrected for bleeding date, 82% of the affected birds had one CK value that deviated 3 or more standard deviations from the mean of other values for the same bird. The results indicate that plasma CK activities can be used to identify affected birds with a high degree of reliability.

Incidence of degenerative myopathy among turkeys fed corn or wheat based rations.

Turkeys were fed either corn based or wheat based rations and necropsied between 28 and 118 weeks of age. Practically all birds affected with degenerative myopathy were detected among those killed between 77 and 85 weeks of age. The incidence of the disease was 0% among 125 males and 7.9% among 139 females. No significant difference in incidence was observed between birds fed corn based and birds fed wheat based rations.

Inheritance of adenosine deaminase variants in chickens and turkeys.

Blood cell lysates of chickens and turkeys were subjected to starch gel electrophoresis and the gels were stained for adenosine deaminase. Two zones were observed singly or together in the electrophoretic patterns of each lysate. Zones of chicken lysates were analogous in electrophoretic mobility to those of turkeys. An extra zone which appeared in patterns of a sample stored over one month was not detected in patterns of a second aliquot of stored sample treated with a reducing agent prior to electrophoresis. Family data involving 110 chicken progeny and 221 turkey progeny supported the hypothesis that these zones were controlled by two codominant alleles designated ADAA and ADAB. In the two Leghorn strains studied ADAB was much more frequent than ADAA, but the frequency distribution was reversed in the Small White turkey strain examined.

Carbonic anhydrase isozymes of blood and oviducal tissues of Leghorn hens.

A group of hens laying high specific gravity eggs and a group laying low specific gravity eggs were selected from each of 6 Single Comb White Leghorn strains and compared for possible qualitative differences in carbonic anhydrase (CA) isozymes in blood and oviducal tissues. Starch gel electrophoretic patterns of erythrocytes, blood plasma and oviducal tissues of magnum, isthmus and uterus from 173 selected hens disclosed 9 carbonic anhydrase isozymes. In oviducal tissues 5 isozyme zones were routinely observed in gel patterns. Of these zones, the 2 with the slowest migration rate had differing staining intensity depending upon the section of the oviduct examined. Five zones were also observed in patterns of lysed erythrocytes, 4 of them possessing the same electrophoretic mobility as 4 to 5 observed in the oviducal tissues, and 1 zone that was observed only in the erythrocytes. Plasma patterns of hens with active ovaries possessed 2 zones, 1 always and 1 occasionally present in patterns of oviducal tissues. Plasma patterns of hens with inactive ovaries possessed 1 or 2 additional unique CA zones. No qualitative differences were found in enzyme patterns between birds laying high specific gravity eggs and those laying low specific gravity eggs.