ELECTROMYOGRAPHIC (EMG) ACTIVITY OF LOWER EXTREMITY MUSCULATURE DURING DROP JUMPING FROM DIFFERENT HEIGHTS

The purpose of this study was to determine EMG activation patterns of the lower extremity musculature during drop jumping from different heights. Ten subjects participated in the study. EMG activity of the rectus femoris, biceps femoris, and gastrocnemious muscles as well as ground reaction forces were simultaneously recorded during drop jumping from 20, 30, and 40cm. Sagittal video data were also recorded and synchronized to the analog data. Results show similar jump height and EMG activation patterns for the 20 and 40cm drop jumps, but not for the 60cm. It was concluded that activation patterns of the lower extremity musculature varies when the drop height exceeds certain limits. The activation pattern of gastrocnemious deviated from the one described in the literatur

Individual-environment interactions in swimming: The smallest unit for analysing the emergence of coordination dynamics in performance?

Displacement in competitive swimming is highly dependent on fluid characteristics, since athletes use these properties to propel themselves. It is essential for sport scientists and practitioners to clearly identify the interactions that emerge between each individual swimmer and properties of an aquatic environment. Traditionally, the two protagonists in these interactions have been studied separately. Determining the impact of each swimmer’s movements on fluid flow, and vice versa, is a major challenge. Classic biomechanical research approaches have focused on swimmers’ actions, decomposing stroke characteristics for analysis, without exploring perturbations to fluid flows. Conversely, fluid mechanics research has sought to record fluid behaviours, isolated from the constraints of competitive swimming environments (e.g. analyses in two-dimensions, fluid flows passively studied on mannequins or robot effectors). With improvements in technology, however, recent investigations have focused on the emergent circular couplings between swimmers’ movements and fluid dynamics. Here, we provide insights into concepts and tools that can explain these on-going dynamical interactions in competitive swimming within the theoretical framework of ecological dynamics

Diagnostic and prognostic value of procalcitonin among febrile critically ill patients with prolonged ICU stay

<p>Abstract</p> <p>Background</p> <p>Procalcitonin (PCT) has been proposed as a diagnostic and prognostic sepsis marker, but has never been validated in febrile patients with prolonged ICU stay.</p> <p>Methods</p> <p>Patients were included in the study provided they were hospitalised in the ICU for > 10 days, were free of infection and presented a new episode of SIRS, with fever >38°C being obligatory. Fifty patients fulfilled the above criteria. PCT was measured daily during the ICU stay. The primary outcome was proven infection.</p> <p>Results</p> <p>Twenty-seven out of 50 patients were diagnosed with infection. Median PCT on the day of fever was 1.18 and 0.17 ng/ml for patients with and without proven infections (p < 0.001). The area under the curve for PCT was 0.85 (95% CI; 0.71-0.93), for CRP 0.65 (0.46-0.78) and for WBC 0.68 (0.49-0.81). A PCT level of 1 ng/mL yielded a negative predictive value of 72% for the presence of infection, while a PCT of 1.16 had a specificity of 100%. A two-fold increase of PCT between fever onset and the previous day was associated with proven infection (p 0.001) (OR = 8.55; 2.4-31.1), whereas a four-fold increase of PCT of any of the 6 preceding days was associated with a positive predictive value exceeding 69.65%. A PCT value less than 0.5 ng/ml on the third day after the advent of fever was associated with favorable survival (p 0.01).</p> <p>Conclusion</p> <p>The reported data support that serial serum PCT may be a valuable diagnostic and prognostic marker in febrile chronic critically ill patients.</p

Variable, but not free-weight, resistance back squat exercise potentiates jump performance following a comprehensive task-specific warm-up

Studies examining acute, high-speed movement performance enhancement following intense muscular contractions (frequently called "post-activation potentiation"; PAP) often impose a limited warm-up, compromizing external validity. In the present study, the effects on countermovement vertical jump (CMJ) performance of back squat exercises performed with or without elastic bands during warm-up were compared. After familiarization, fifteen active men visited the laboratory on two occasions under randomized, counterbalanced experimental squat warm-up conditions: (a) free-weight resistance (FWR) and (b) variable resistance (VR). After completing a comprehensive task-specific warm-up, three maximal CMJs were performed followed by three back squat repetitions completed at 85% of 1-RM using either FWR or VR Three CMJs were then performed 30 seconds, 4 minutes, 8 minutes, and 12 minutes later. During CMJ trials, hip, knee, and ankle joint kinematics, ground reaction force data and vastus medialis, vastus lateralis, and gluteus maximus electromyograms (EMG) were recorded simultaneously using 3D motion analysis, force platform, and EMG techniques, respectively. No change in any variable occurred after FWR (P > 0.05). Significant increases (P < 0.05) were detected at all time points following VR in CMJ height (5.3%-6.5%), peak power (4.4%-5.9%), rate of force development (12.9%-19.1%), peak concentric knee angular velocity (3.1%-4.1%), and mean concentric vastus lateralis EMG activity (27.5%-33.4%). The lack of effect of the free-weight conditioning contractions suggests that the comprehensive task-specific warm-up routine mitigated any further performance augmentation. However, the improved CMJ performance following the use of elastic bands is indicative that specific alterations in force-time properties of warm-up exercises may further improve performance

Automated office blood pressure measurements in primary care are misleading in more than one third of treated hypertensives: The VALENTINE-Greece Home Blood Pressure Monitoring study

Abstract Background This study assessed the diagnostic reliability of automated office blood pressure (OBP) measurements in treated hypertensive patients in primary care by evaluating the prevalence of white coat hypertension (WCH) and masked uncontrolled hypertension (MUCH) phenomena. Methods Primary care physicians, nationwide in Greece, assessed consecutive hypertensive patients on stable treatment using OBP (1 visit, triplicate measurements) and home blood pressure (HBP) measurements (7 days, duplicate morning and evening measurements). All measurements were performed using validated automated devices with bluetooth capacity (Omron M7 Intelli-IT). Uncontrolled OBP was defined as ≥140/90 mmHg, and uncontrolled HBP was defined as ≥135/85 mmHg. Results A total of 790 patients recruited by 135 doctors were analyzed (age: 64.5 ± 14.4 years, diabetics: 21.4%, smokers: 20.6%, and average number of antihypertensive drugs: 1.6 ± 0.8). OBP (137.5 ± 9.4/84.3 ± 7.7 mmHg, systolic/diastolic) was higher than HBP (130.6 ± 11.2/79.9 ± 8 mmHg; difference 6.9 ± 11.6/4.4 ± 7.6 mmHg, p Conclusions In primary care, automated OBP measurements are misleading in approximately 40% of treated hypertensive patients. HBP monitoring is mandatory to avoid overtreatment of subjects with WCH phenomenon and prevent undertreatment and subsequent excess cardiovascular disease in MUCH

Recovery kinetics of knee flexor and extensor strength after a football match

© 2015 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0128072We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12h (both limbs) and 36h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36h at 60°/s and for 60h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level.Published versio

Physical activity in pre-school children: Trends over time and associations with body mass index and screen time

Background: Pre-school years are important for adopting health behaviours; however, today’s children seem to be overweight, present low physical activity (PA) levels and exceed screen time (ST) recommendations. Aim: To examine (a) time trends in PA in Greek pre-school children, (b) the associations among PA, body mass index (BMI) and ST and (c) potential PA differences between boys and girls. Subjects and methods: Data from five cross-sectional cohorts (2005 [n = 252]; 2008 [n = 212]; 2011 [n = 187]; 2014 [n = 194]; 2017 [n = 128]) were compared. PA was assessed using Omron HJ-720IT-E2 pedometers, whereas ST was reported by participants’ parents. A 4-way ANOVA was applied on children’s average week step counts. Results: A significant association (F = 828.90, p &amp;lt; 0.001, η2 = 0.638) between ST and PA was revealed, with children that had ST &amp;lt; 1 hour/day presenting the higher PA levels and being the only ones that met PA recommendations (11,500 steps/day). Statistically significant PA differences, though of no practical importance, were found among cohorts. There were no significant PA differences between boys and girls or among BMI categories. Nevertheless, obesity prevalence was found to exist at alarming levels (24.5% in 2008–41.4% in 2017), and a large percentage of children (23.6% in 2008–63.3% in 2017) presented excessive ST (&amp;gt; 2 hours/day). Conclusion: Effective interventions aiming at reducing ST and enhancing PA seem imperative if children’s health is to be safeguarded. © 2019, © 2019 Informa UK Limited, trading as Taylor &amp; Francis Group

Physiological responses during interval training at relative to critical velocity intensity in young swimmers

Objectives: The purpose of this study was to examine the physiological responses on three interval training sets performed at intensities relative to the critical velocity which was calculated from two different combinations of distances using a 2-parameter linear model. Methods: In a controlled repeated measures design, ten male well trained swimmers (age: 15.2±1.2years) swam 5×400-m, 10×200-m and 20×100-m on separate days with rest to swimming ratio 1:8, aiming to maintain the critical velocity calculated from distances of 50, 100, 200, 400-m (CV4) or 200, 400-m (CV200-400). Results: The sustained velocity on the 5×400-m was lower compared to CV4 and velocity on the 20×100-m was higher compared to CV200-400. The velocity on the 10×200-m was kept similar to both CV4 and CV200-400 (5×400-m: 1.27±0.07 vs. CV4: 1.33±0.09ms-1, p&amp;lt;0.05; 20×100-m: 1.32±0.02 vs. CV200-400: 1.28±0.09ms-1, p&amp;lt;0.05; 10×200-m: 1.30±0.10ms-1 vs. CV4 and CV200-400, p&amp;gt;0.05). The blood lactate concentration increased after 1200 compared to 400-m (4.45±0.23 vs. 5.82±0.24mmoll-1, p&amp;lt;0.05) and was no different between sets (p&amp;gt;0.05). Stroke rate and stroke length were not different between and within conditions (p&amp;gt;0.05). Heart rate during the recovery periods was lower in the 5×400-m compared to 10×200-m and 20×100-m training set (p&amp;lt;0.05). Conclusion: Interval swimming pace can be adjusted in relation to critical velocity calculated from distances of 200 and 400-m or from distance of 50, 100, 200, 400m. When the distance of repetitions is increased from 100 to 200 and 400-m the velocity should be reduced by 2% to achieve similar metabolic responses. © 2011 Sports Medicine Australia

Enhancing motor competence and physical activity in kindergarten

Background: This study aimed at evaluating the effect of the “Walk,” an 8-month physical activity (PA) program led by classroom and physical education teachers, on the motor competence (MC) and PA of 5- to 6-year-old children. Methods: A total of 143 children (mean age = 61.51 [1.85] mo) participated in the study and were randomly assigned to the experimental and control groups. Children&apos;s MC was assessed by the Körperkoordination Test für Kinder (KTK), and PA was objectively measured by Omron HJ-720IT-E2 pedometers. Measurements were performed at baseline, midintervention, and postintervention. A 1-sample t test computed at baseline step counts revealed that children presented significantly lower PA than recommended for their age (P &amp;lt; .001). To examine the effect of the intervention on children&apos;s MC and PA, several repeated-measures analyses of variance were utilized on (1) KTK item scores and (2) pedometer data. Results: The results revealed that the Walk project led to practically significant changes in the experimental group compared with the control group in both MC (P &amp;lt; .001, η 2 &amp;gt; .14 for all KTK items) and PA (P &amp;lt; .001, η 2 = .23). Conclusions: This study highlights the efficacy of a PA project, involving both classroom and physical education teachers, for the enhancement of children&apos;s MC and PA. © 2019 Human Kinetics, Inc