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result(s) for
"Roos, Lilian"
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Analysis of the multi-segmental postural movement strategies utilized in bipedal, tandem and one-leg stance as quantified by a principal component decomposition of marker coordinates
2013
Postural control research describes ankle-, hip-, or multi-joint strategies as mechanisms to control upright posture. The objectives of this study were, first, development of an analysis technique facilitating a direct comparison of the structure of such multi-segment postural movement patterns between subjects; second, comparison of the complexity of postural movements between three stances of different difficulty levels; and third, investigation of between-subject differences in the structure of postural movements and of factors that may contribute to these differences.
Twenty-nine subjects completed 100-s trials in bipedal (BP), tandem (TA) and one-leg stance (OL). Their postural movements were recorded using 28 reflective markers distributed over all body segments. These marker coordinates were interpreted as 84-dimensional posture vectors, normalized, concatenated from all subjects, and submitted to a principal component analysis (PCA) to extract principal movement components (PMs). The PMs were characterized by determining their relative contribution to the subject's entire postural movements and the smoothness of their time series.
Four, eight, and nine PM were needed to represent 90% of the total variance in BP, TA, and OL, respectively, suggesting that increased task difficulty is associated with increased complexity of the movement structure. Different subjects utilized different combinations of PMs to control their posture. In several PMs, the relative contribution of a PM to a subject's overall postural movements correlated with the smoothness of the PM's time series, suggesting that utilization of specific postural PMs may depend on the subject's ability to control the PM's temporal evolution.
Journal Article
Validity of sports watches when estimating energy expenditure during running
2017
Background
The aim of this study was to assess the accuracy of three different sport watches in estimating energy expenditure during aerobic and anaerobic running.
Methods
Twenty trained subjects ran at different intensities while wearing three commercial sport watches (Suunto Ambit2, Garmin Forerunner920XT, and Polar V800). Indirect calorimetry was used as the criterion measure for assessing energy expenditure. Different formulas were applied to compute energy expenditure from the gas exchange values for aerobic and anaerobic running.
Results
The accuracy of the energy expenditure estimations was intensity-dependent for all tested watches. During aerobic running (4–11 km/h), mean absolute percentage error values of −25.16% to +38.09% were observed, with the Polar V800 performing most accurately (stage 1: −12.20%, stage 2: −3.61%, and stage 3: −4.29%). The Garmin Forerunner920XT significantly underestimated energy expenditure during the slowest stage (stage 1: −25.16%), whereas, the Suunto Ambit2 significantly overestimated energy expenditure during the two slowest stages (stage 1: 38.09%, stage 2: 36.29%). During anaerobic running (14–17 km/h), all three watches significantly underestimated energy expenditure by −21.62% to −49.30%. Therefore, the error in estimating energy expenditure systematically increased as the anaerobic running speed increased.
Conclusions
To estimate energy expenditure during aerobic running, the Polar V800 is recommended. By contrast, the other two watches either significantly overestimated or underestimated energy expenditure during most running intensities. The energy expenditure estimations generated during anaerobic exercises revealed large measurement errors in all tested sport watches. Therefore, the algorithms for estimating energy expenditure during intense activities must be improved before they can be used to monitor energy expenditure during high-intensity physical activities.
Journal Article
Impact of Training Patterns on Injury Incidences in 12 Swiss Army Basic Military Training Schools
2014
Non-battle injury rates are a major health problem in the armed forces today. Injury rates are related to physical demands of daily military routine. The aim of this study is to investigate the impact of different physical training patterns on incidences of injuries in 12 Swiss Army basic military training schools. Therefore, injury data of 1,676 voluntary participant recruits and objective sensor data on physical demands of 50 volunteers at each of 12 trainings schools were assembled. Multiple linear regression showed that high physical demands, decreasing development of distances covered on foot, monotony in weekly physical demands, little time spent on sport-related physical training, and little time for night rest were significant risk factors for injuries. Together, those variables describe 98.8% of the variances of total injury incidence rate between military training schools. The new method used to objectively assess training demands allowed this study to investigate the impact of training patterns on injury incidence in a large number of training schools. The results of this study are important for future interventions to reduce injury incidence rates in a military setting by quantifying the injury risk potential of a large number of training patterns.
Journal Article
Musculoskeletal Injuries and Training Patterns in Junior Elite Orienteering Athletes
2015
Findings about the relation between musculoskeletal injuries and training patterns in orienteering athletes are sparse. Therefore, the musculoskeletal injuries and training patterns of 31 Swiss elite orienteering athletes aged 18-19 years were analyzed in a retrospective study. Individual training diaries and medical records were used to assess training data and injury history, respectively. Group comparisons and a multiple linear regression (MLR) were performed for statistical analysis. The junior elite orienteering athletes performed 7.38 ± 2.00 training sessions weekly, with a total duration of 455.75 ± 98.22 minutes. An injury incidence rate (IIR) of 2.18 ± 2.13 injuries per 1000 hours of training was observed. The lower extremity was affected in 93% of all injuries, and the knee (33%) was the most commonly injured location. The MLR revealed that gender and six training variables explained 60% of the variance in the injury severity index in this study. Supported by the low IIR in the observed age group, the training protocol of the junior elite orienteering athletes was generally adequate. In comparison to elite track, marathon, and orienteering athletes, the junior elite athletes performed less high-intensity interval training (HIIT). However, more frequent HIIT seems to be a protective factor against injuries.
Journal Article
Transformational Leadership, Achievement Motivation, and Perceived Stress in Basic Military Training: A Longitudinal Study of Swiss Armed Forces
by
Roos, Lilian
,
Brand, Serge
,
Pramstaller, Maria
in
Achievement motivation
,
Armed forces
,
Employees
2021
In Switzerland, military service is a civic obligation for all adult male citizens, and thus, leadership style can be particularly challenging. The present study investigated the impact of superiors’ leadership styles on recruits’ achievement motivation, organizational citizenship behavior (OCB), and perceived stress during their Basic Military Training (BMT). To this end, a total of 525 male recruits (mean age: 20.3 years) recruits were assessed both cross-sectionally and longitudinally. At the start of BMT (baseline), at week 7, and at week 11, participants completed a series of self-rating questionnaires covering demographic information, achievement motivation, organizational citizenship behavior (OCB), perceived stress, and their superiors’ leadership styles (transformational, transactional und laissez-faire). Longitudinally, scores for achievement motivation and OCB showed no significant difference between baseline and the 11th week. In a group comparison, the group experiencing higher transformational leadership (from week 7 to week 11) had the highest scores for achievement motivation and OCB, and the lowest scores for perceived stress, all at week 11. Exploratively, achievement motivation and OCB at baseline were associated with transformational leadership and transactional leadership at week 7 and week 11. Perceived stress at baseline correlated only with transformational leadership but not with transactional leadership, both at week 7 and week 11. Transformational leadership style fostered achievement motivation and OCB in Swiss military recruits and protected them from stress, both cross-sectionally and longitudinally.
Journal Article
Adapted Marching Distances and Physical Training Decrease Recruits' Injuries and Attrition
2015
There is evidence that progressive loading of physical demands at the beginning of basic military service and specific physical training can reduce injury incidences. Therefore, aim of this study was to measure the effects of a progressive increase in marching distances and an adapted physical training program on injury incidence and attrition rate in a Swiss Army infantry training school. One company reduced the distances covered on foot during the first 4 weeks of basic military training. A second company performed an adapted physical training program for 10 weeks. A third company participated in both interventions combined, and a fourth company served as a control group without any intervention. The injury incidences and attrition rates of 651 male recruits were registered during 21 weeks of military service. Several predictor variables for injury and attrition, such as physical fitness, previous injuries, level of previous physical activity, smoking, motivation, and socioeconomic factors, were assessed as well. The data were analyzed using binary logistic backward regressions. Each intervention separately had a favorable effect on injury prevention. However, combining the 2 interventions resulted in the greatest reduction in injury incidence rate (-33%). Furthermore, the adapted physical training successfully reduced the military service attrition rates (-53%).
Journal Article
Gastroprotective Effects of the Aqueous Extract from Taraxacum officinale in Rats Using Ultrasound, Histology, and Biochemical Analysis
by
Oliveira, Beatriz M. M.
,
Bohnen, Lilian
,
Zanatta, Maria Eduarda D. C.
in
Acids
,
Animals
,
Biochemical analysis
2021
Taraxacum officinale F.H. Wigg. belonging to the family Asteraceae is an edible medicinal plant distributed worldwide. This study aimed to determine the gastroprotective effects of aqueous extract of T. officinale (AETo) in rats using ultrasound, histological, and biochemical analyses. In this study, gastric ulceration was induced by ethanol or piroxicam. Rats were then treated with AETo (3, 30, or 300 mg/kg). The area and histological appearance of gastric ulcers were quantified, and histochemical analysis was performed. The activity of AETo on inflammatory and oxidative stress markers was assessed in the ulcerated tissue. In addition, we investigated the thickness of the gastric wall using the ultrasound technique. Moreover, chemical analyses of AETo were performed. In rats with ethanol- or piroxicam-induced ulcers, AETo reduced the ulceration area, elevated mucin level, and the gastroprotective effect was confirmed by histological analysis. The gastroprotective effect was accompanied by increased activities of SOD, CAT, and GST, as well as an increase in GSH level and reduction in MPO activity. Furthermore, AETo reduced the thickness of the gastric wall in rats. Phytochemical analysis of AETo indicated phenolic acids and flavonoids as the main active compounds. In conclusion, the gastroprotective effect of AETo involves reduction in oxidative stress and inflammatory injury and increase in mucin content. This study advances in the elucidation of mechanisms of gastric protection of T. officinale, contributes to the prospection of new molecules gastroprotective, and proposes the ultrasonographic analyses as a new gastroprotective assessment tool in preclinical studies.
Journal Article