The effect of progressive and individualised sport-specific training on the prevalence of injury in football and handball student athletes: a randomised controlled trial

Objective: To evaluate the effectiveness of communication and coordination combined with designing a progressive and individualised sport-specific training program for reducing injury prevalence in youth female and male football and handball players transitioning to a sports academy high school. An additional aim was to investigate the characteristics of the reported injuries. Methods: Forty-two Norwegian athletes were randomised into an intervention or control group. Mean age, height, weight and BMI was 15.5 ± 0.5 years, 178.6 cm ± 6.3 cm, 71.3 ± 9.8 kg, 22.3 ± 2.7 BMI for the intervention group (IG) (n = 23), and 15.4 ± 0.5 years, 175.6 cm ± 6.6 cm, 67.1 ± 9.8 kg, 21.7 ± 2.4 BMI for the control group (CG) (n = 19). During the summer holiday, the intervention group received weekly progressive, individualised sport-specific training programs and weekly follow-up telephone calls from the researchers. All athletes completed a baseline questionnaire and a physical test battery. Training data and injuries were recorded prospectively for 22 weeks using the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2). A two-way chi-square (χ2) test of independence was conducted to examine the relationship between groups and injury. Results: Average weekly prevalence of all injuries was 11% (95% CI: 8%–14%) in IG and 19% (95% CI: 13%–26%) in CG. Average weekly prevalence of substantial injuries was 7% (95% CI: 3%–10%) in IG and 10% (95% CI: 6%–13%) in CG. The between-group difference in injuries was significant: χ2 (1, N = 375) = 4.865, p = .031, φ = .114, with 1.8 times higher injury risk in CG vs. IG during the first 12 weeks after enrolment. Conclusions: For student athletes transitioning to a sports academy high school, progressive individualised, sport-specific training programs reduced the prevalence of all-complaint injuries following enrolment. Clubs and schools should prioritise time and resources to implement similar interventions in periods where student athletes have less supervision, such as the summer holidays, to facilitate an optimal transition to a sports academy high school.publishedVersio

Core temperature in triathletes during swimming with wetsuit in 10 °C cold water

Low water temperature (<15 °C) has been faced by many organizers of triathlons and swim-runs in the northern part of Europe during recent years. More knowledge about how cold water affects athletes swimming in wetsuits in cold water is warranted. The aim of the present study was therefore to investigate the physiological response when swimming a full Ironman distance (3800 m) in a wetsuit in 10 °C water. Twenty triathletes, 37.6 ± 9 years (12 males and 8 females) were recruited to perform open water swimming in 10 °C seawater; while rectal temperature (Tre) and skin temperature (Tskin) were recorded. The results showed that for all participants, Tre was maintained for the first 10−15 min of the swim; and no participants dropped more than 2 °C in Tre during the first 30 min of swimming in 10 °C water. However; according to extrapolations of the results, during a swim time above 135 min; 47% (8/17) of the participants in the present study would fall more than 2 °C in Tre during the swim. The results show that the temperature response to swimming in a wetsuit in 10 °C water is highly individual. However, no participant in the present study dropped more than 2 °C in Tre during the first 30 min of the swim in 10 °C water

Fluctuation in Shear Rate, with Unaltered Mean Shear Rate, Improves Brachial Artery Flow-Mediated Dilation in Healthy, Young Men.

AIM: Increase in mean shear stress represents an important and potent hemodynamic stimulus to improve conduit artery endothelial function in humans. No previous study has examined whether fluctuations in shear rate patterns, without altering mean shear stress, impacts conduit artery endothelial function. This study examined the hypothesis that 30-minutes exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. METHODS: Fifteen healthy males (27.3±5.0 years) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30-minutes of intermittent negative pressure (10seconds -40mmHg, 7seconds 0mmHg) to induce fluctuation in shear rate, whilst the contra-lateral arm was exposed to a resting period. RESULTS: Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P<0.001). Across the 30-minute intervention, mean shear rate was not different compared to baseline (P=0.458). A linear mixed model revealed a significant effect of time was observed for flow-mediated dilation (P=0.029), with exploratory post-hoc analysis showing an increase in the intervention arm (∆FMD +2.0%, P=0.008), but not in the contra-lateral control arm (∆FMD +0.5%, P=0.664). However, there was no effect for arm (P=0.619) or interaction effect (P=0.096). CONCLUSION: In conclusion, we found that fluctuations in shear patterns, with unaltered mean shear, improves brachial artery flow-mediated dilation. These novel data suggest that fluctuations in shear pattern, even in the absence of altered mean shear, represents a stimulus to acute change in endothelial function in healthy individuals

Diabetic foot assessment using skin impedance in a custom made sensor-sock

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Applications of bioimpedance measurement techniques in tissue engineering

Rapid development in the field of tissue engineering necessitates implementation of monitoring methods for evaluation of the viability and characteristics of the cell cultures in a real-time, non-invasive and non-destructive manner. Current monitoring techniques are mainly histological and require labeling and involve destructive tests to characterize cell cultures. Bioimpedance measurement technique which benefits from measurement of electrical properties of the biological tissues, offers a non-invasive, label-free and real-time solution for monitoring tissue engineered constructs. This review outlines the fundamentals of bioimpedance, as well as electrical properties of the biological tissues, different types of cell culture constructs and possible electrode configuration set ups for performing bioimpedance measurements on these cell cultures. In addition, various bioimpedance measurement techniques and their applications in the field of tissue engineering are discussed

Increased LV apical untwist during preload reduction in healthy humans. An echocardiographic speckle tracking study during lower body negative pressure (LBNP)

Background: We sought to investigate the effect of reduced preload on LV untwist and early diastolic filling in healthy individuals. Methods: Twelve healthy men, 22 (22,23) years of age, were examined at rest and during applied lower body negative pressure (LBNP) of -20 mmHg and -40 mmHg, respectively. Regional untwist and untwist rate during IVRT were calculated at LV basal, papillary, sub-papillary and apical short axis levels by two dimensional speckle tracking echocardiography. LV early diastolic filling was assessed by transmitral E-wave (E) peak velocity by pulsed Doppler and flow propagation velocity (Vp) by color M-mode Doppler and early diastolic pulsed Doppler tissue velocities (E`) from septal and lateral mitral annulus. Results: From rest to LBNP -40 mmHg the LV untwist and untwist rate at sub-papillary level increased from 2.3 (1.4,3.5) to 4.5 (3.1,7.6) degrees and from -36 (-51,-25) to -69 (-127,-42) °/s (p<0.001, p=0.003), respectively, while apical untwist and untwist rate increased from 3.9 (2.3,4.3) to 7.6 (6.4,10.5) degrees and from -51 (-69,-40) to -118 (-170,-84) °/s (p<0.001, p<0.001), respectively. Since untwist and untwist rate at the basal level were unchanged, this created markedly larger base to apical untwist and untwist rate gradients from rest to LBNP -40 mmHg. E, Vp and E` were reduced by 34, 32 and 39 %, respectively. Conclusions: LV untwist and untwist rate during IVRT were increased at apical levels, which might be a physiological mechanism to minimize the impairment in LV early diastolic filling during preload reduction

A Novel Design of an Optical Probe for Detecting Perfusion Changes in Buccal Tissue

Measuring the blood perfusion and microcirculation at a specific depth in human tissue is an important method to monitor oxygenation in critically ill patients. The optical probes that are currently available in the market are not capable of monitoring the blood perfusion from a given tissue layer and at a specific depth. We have designed a novel optical probe which is able to focus the light at a specific depth of ~ 670 ìm in buccal tissue. The new probe consists of two light guides for sending and detecting the reflected light from the sampling area (tissue), and a lens to focus the light into the desired depth of the tissue and collect it back from the same area. The new optical probe has been compared to a commercial laser Doppler probe by collecting data from the same sampling area. The result from our probe showed 15% higher accuracy in detecting changes in blood perfusion compared with an existing commercial probe

Cerebral blood flow velocity during simultaneous changes in mean arterial pressure and cardiac output in healthy volunteers

Abstract Purpose Cerebral blood flow (CBF) needs to be precisely controlled to maintain brain functions. While previously believed to be autoregulated and near constant over a wide blood pressure range, CBF is now understood as more pressure passive. However, there are still questions regarding the integrated nature of CBF regulation and more specifically the role of cardiac output. Our aim was, therefore, to explore the effects of MAP and cardiac output on CBF in a combined model of reduced preload and increased afterload. Method 16 healthy volunteers were exposed to combinations of different levels of simultaneous lower body negative pressure and isometric hand grip. We measured blood velocity in the middle cerebral artery (MCAV) and internal carotid artery (ICAV) by Doppler ultrasound, and cerebral oxygen saturation (ScO 2 ) by near-infrared spectroscopy, as surrogates for CBF. The effect of changes in MAP and cardiac output on CBF was estimated with mixed multiple regression. Result Both MAP and cardiac output had independent effects on MCAV, ICAV and ScO 2 . For ICAV and ScO 2 there was also a statistically significant interaction effect between MAP and cardiac output. The estimated effect of a change of 10 mmHg in MAP on MCAV was 3.11 cm/s (95% CI 2.51–3.71, P  &lt; 0.001), and the effect of a change of 1 L/min in cardiac output was 3.41 cm/s (95% CI 2.82–4.00, P  &lt; 0.001). Conclusion The present study indicates that during reductions in cardiac output, both MAP and cardiac output have independent effects on CBF

Intraocular Pressure Increases in Parallel with Systemic Blood Pressure during Isometric Exercise

PURPOSE. Normal-tension glaucoma has been found to be related to transient increases in intraocular pressure (IOP). Isometric exercise induces a pressor response with a characteristic increase in blood pressure. The purpose of the present study was to investigate how transient changes in systemic blood pressure, induced by isometric exercise, affect IOP. METHODS. Nine healthy volunteers participated in the study. Systemic blood pressure, heart rate (ECG) and IOP (electronic continuous-indentation tonometer) were recorded continuously before, during, and after a 2-minute period of isometric exercise (40% maximum voluntary contraction of the forearm). RESULTS. During the 2-minute isometric exercise, heart rate increased from 74 Ϯ 6 beats/min (mean Ϯ SEM) to 93 Ϯ 6 beats/min (P Ͻ 0.005) and systolic and diastolic arterial blood pressure increased from 125 Ϯ 6 to 169 Ϯ 8 mm Hg (P Ͻ 0.005) and from 65 Ϯ 3 to 96 Ϯ 5 mm Hg (P Ͻ 0.005), respectively. IOP increased from 15 Ϯ 1 mm Hg at rest to 19 Ϯ 2 mm Hg at the end of the isometric exercise (P Ͻ 0.005). CONCLUSIONS. During isometric exercise, IOP increased continuously, as long as the isometric exercise persisted, in parallel to the increase in systemic blood pressure. (Invest Ophthalmol Vis Sci. 2009;50:760 -764

The role and development of sprinting speed in soccer

Author's version of an article in the journal: International Journal of Sports Physiology and Performance. Also available from the publisher at: http://dx.doi.org/10.1123/IJSPP.2013-0121The overall objective of this review was to investigate the role and development of sprinting speed in soccer. Time–motion analyses show that short sprints occur frequently during soccer games. Straight sprinting is the most frequent action before goals, both for the scoring and assisting player. Straight-line sprinting velocity (both acceleration and maximal sprinting speed), certain agility skills, and repeated-sprint ability are shown to distinguish groups from different performance levels. Professional players have become faster over time, indicating that sprinting skills are becoming more and more important in modern soccer. In research literature, the majority of soccer-related training interventions have provided positive effects on sprinting capabilities, leading to the assumption that all kinds of training can be performed with success. However, most successful intervention studies are time consuming and challenging to incorporate into the overall soccer training program. Even though the principle of specificity is clearly present, several questions remain regarding the optimal training methods within the larger context of the team-sport setting. Considering time-efficiency effects, soccer players may benefit more by performing sprint-training regimens similar to the progression model used in strength training and by world-leading athletics practitioners, compared with the majority of guidelines that traditionally have been presented in research literature