Written informed consent was received from all participants and p

Written informed consent was received from all participants and parents after detailed explanation about Imatinib Mesylate manufacturer the aims, benefits, and risks involved with this investigation. Participants with self-reported history of neurological or musculoskeletal conditions affecting the balance control system were excluded from the study. Prior to testing, all participants completed a physical activity questionnaire (PAQ-C) to assess their basic activity level. Body height was measured and recorded in cm to the nearest mm. Body mass was measured to the nearest 0.1 kg with an electronic weight scale with the participant in shorts and T-shirt. BMI was calculated for each participant. The experimental session comprised of nine balance trials, three trials each of three sensory conditions, with each trial lasting 30 seconds in order to have reliable postural sway measures (Le Clair and Riach, 1996).

According to the findings of Geldhof et al. (2006) who used similar methods to the present study, the composite inter-test reliability of three trials has an ICC of 0.77. The sequence of the conditions was randomised with a one-minute rest period between conditions to avoid learning or fatigue effects. Participants were asked to stand barefoot quietly, with each foot on a separate force platform (1Hz, Models 4060-08 and 6090, Bertec Corporation, Columbus, OH, USA) embedded in the ground. Participants used a safety harness to prevent them from injury in case of an irrecoverable balance loss. The harness has proven to be safe without impeding natural quiet standing (Freitas et al., 2005).

The children stood with feet shoulder-width apart and arms hanging loosely at their sides for each trial. During the CONTROL and EOCS conditions, children were standing and gazed straight ahead at a 3 m far target. However, they were not required to fix their gaze on any particular spot. For the latter condition, a 10 cm thick layer of foam was placed on top of each force platform to interfere with somatosensory information from the feet and ankles. The COP and torque on the force platform were calculated from the force and moment components of the force platform data. The displacement of COP is the reaction to body dynamics (Winter, 1995) and follows the neuromuscular control signal to maintain the position the COM within the BOS and achieve equilibrium (Riley et al., 1990).

To obtain a quantitative description of standing ability, the following COP parameters were computed. COP path velocity (COP-PV): the average distance travelled by the COP per second. COP-PV is assumed to decrease with better balance performance. GSK-3 COP radial displacement (COP-RD): the mean radial distance of the COP from the centroid of the COP path over the entire trial. COP-RD data were normalized by expressing the results relative to the height of the participant. COP-RD is presumed to decrease with better balance performance.

This velocity was selected since it is often used in training, re

This velocity was selected since it is often used in training, representing http://www.selleckchem.com/products/pacritinib-sb1518.html the maximum aerobic velocity that swimmers can maintain without accumulation of fatigue (approximately 30 min) (Olbrecht, 2000; Fernandes et al., 2010). Previous studies conducted in order to observe whether the hip accurately represents the intracycle CM profile in front crawl have been carried out at much higher intensities (Maglischo et al., 1987; Psycharakis and Sanders, 2009). As results, higher IVV values were expected due to a significant increase in both propulsive and drag forces (Schnitzler et al., 2010). In fact, Barbosa et al. (2006) found a linear relationship between IVV and energy cost, and, therefore, with velocity, in the front crawl.

In the current study, a 2D kinematical recording was implemented since it requires less digitizing time and has fewer methodological problems. In fact, the 2D approach is conceptually easier to relate to, and can yield acceptable results (Bartlett, 2007), being proper to evaluate numerous samples and to implement in field studies, particularly in the swimming club. Conversely, the 3D analysis is a very time-consuming process that requires complex analytical methods, what makes it difficult for coaches to use on a day-to-day basis (Psycharakis and Sanders, 2009). CM and hip presented similar mean values for both forward velocity and displacement. Such a result was expected once the CM is located in the hip region (Costill et al., 1987; Maglischo et al., 1987; Figueiredo et al., 2009).

In fact, nonetheless the mean error concerning the hip and CM displacement towards a slight tendency for a hip underestimation, the approximately 0 velocity mean error values indicate that the hip seems not to under or overestimate the CM velocity values. This is in line with the literature, as Maglischo et al. (1987) concluded that forward velocity of the hip can be a useful tool for diagnosing problems within stroke cycles. However, the values of RMS error and percentage of error evidence the opposite behaviour: although being of low magnitude, the error is higher regarding forward velocity (7.54%) than the displacement (3.24%). It is accepted that the RMS error should be considered preferably to the mean error, since the hip frequently underestimates or overestimates the CM due to differences in swimmers�� technique (negative errors cancelled by the positive ones), and because RMS is considered a conservative estimate of accuracy (Allard et al.

, 1995). Furthermore, high and very high positive correlation coefficients were found between the hip and the CM regarding horizontal swimming velocity and displacement, Dacomitinib as seen in front crawl (Costill et al., 1987; Maglischo et al., 1987, Figueiredo et al., 2009), backstroke (Maglischo et al., 1987), breaststroke (Costill et al., 1987; Maglischo et al., 1987), and butterfly (Maglischo et al., 1987; Barbosa et al.

COP-AV is assumed to decrease with

COP-AV is assumed to decrease with selleck chemical improved balance ability (Winter, 1990). The children completed the PAQ-C (Crocker et al., 1997), a physical activity (PA) level questionnaire designed to quantify their daily activity level, which is a guided self-administered 7-day recall measure for children. It provides a summary PA score derived from nine items, each scored on a 5-point scale. A score of 5 indicates high PA level, whereas a score of 1 indicates low PA. The PAQ-C has been suggested as one of the most reliable and valid self-administered recall instruments (Crocker et al., 1997). Data are described as means ��SD. An independent sample t-test was used to examine the gender difference in postural stability parameters, whereas one-way ANOVA was used to examine the differences between conditions.

Effect sizes (Cohen��s d) were calculated to determine the practical difference between girls and boys. Effect size values of 0�C0.19, 0.20�C0.49, 0.50�C0.79 and 0.8 and above were considered to represent trivial, small, medium and large differences, respectively (Cohen, 1988). Pearson product moment correlation coefficient was used to assess the relationship between COP parameters and other variables. The magnitude of the correlations was determined using the modified scale by Hopkins (2000): trivial: r < 0.1; low: 0.1�C0.3; moderate: 0.3�C0.5; high: 0.5�C0.7; very high: 0.7�C0.9; nearly perfect > 0.9; and perfect: 1. Significance level was defined as p < 0.05. Results Significant gender differences (p < 0.05) were observed in COP-PV, COP-RD and COP-AV when the three conditions were pooled (Table 1).

Specifically, boys had significantly higher COPPV (p < 0.05, medium effect), longer COP-RD (p < 0.05, medium effect), and higher COP-AV (p < 0.05, medium effect), as compared to girls. Furthermore, COP-RD (p < 0.05, large effect) and COP-AV (p < 0.05, large effect) were significantly different between genders in CONTROL condition (Table 1), indicating the sensitivity of these two parameters in differentiating postural stability between genders in this age group. Table 1 Gender difference in postural stability performance and percentage change from CONTROL in postural stability performance for girls and boys with effect sizes, effect size magnitudes and 95% confidence intervals The data in Table 1 include the analysis of the percentage change from the CONTROL condition and these data are presented in Figure 1.

While there were no significant gender differences in the percentage change in COP-PV for either ECHB or EOCS, there was a significant gender difference (p > 0.05) in COP-RD for the ECHB condition with a medium gender effect for EOCS. There were medium gender effects in COP-AV Brefeldin_A in both ECHB and EOCS conditions. Figure 1 Percentage change (with reference to CONTROL) in postural stability performance for boys and girls (* indicate significant gender difference: p<0.

049) (ES �� 0 97) Figure 2 Example of raw

049) (ES �� 0.97). Figure 2 Example of raw selleck chem Alisertib EMG of rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) after different acute stretching methods (pre-static, post-static, pre-dynamic, and post-dynamic) during soccer instep kicking Figure 3 Mean �� SD changes in rectus femoris, vastus lateralis, and vastus medialis root mean square EMG during soccer instep kicking before and after static and dynamic stretching. Significant at p < 0.015, Significant at p < 0.004, Significant ... Table 2 Mean (�� SD) muscles activity, knee and ankle joints angular velocity, and foot and ball velocity descriptors of the soccer instep kicking after different acute stretching methods KAV showed a significant increase by 9.65% �� 4.92% after dynamic stretching (p = 0.002) versus a non-significant change (?1.

45% �� 4.84%) after static stretching (ES �� 0.98). Dynamic stretching (10.12% �� 5.32%) also showed greater AAV than static stretching (?3.29% �� 3.68%) (p = 0.011) (ES �� 0.96). In addition, dynamic stretching (10.77% �� 7.12%) caused significantly faster BV when compared to static stretching (?6.56% �� 3.67%) (p = 0.001) (ES �� 0.99). Discussion The main finding of this study is that, compared to static stretching, dynamic stretching of the quadriceps resulted in a higher increase of (1) VM, VL and RF muscle activation, (2) maximum knee and ankle angular velocity and (3) maximum ball velocity during an instep soccer kick. Further, dynamic stretching caused a higher increase of RF muscle activity as opposed to VM and VL muscles. The present results support previous research studies (Cramer et al.

, 2005; Marek et al., 2005) indicating that dynamic stretching increases activation of all superficial quadriceps muscles more than static stretching (Figure 3). However, in contrast to previous research studies, our results refer to a multiarticular movement, such as the soccer kick and therefore, direct comparison between the aforementioned studies is difficult. Particularly, backward and forward swinging motion of the kicking leg is mainly accompanied by a fast stretch-shortening cycle of the quadriceps (Bober et al., 1987). Along with the motion-dependent moments, the knee extensors provide the main force in order to accelerate the shank during the forward motion of the kicking leg (Kellis et al., 2006; Dorge et al., 1999).

A higher quadriceps activation and strength, coupled with a more efficient stretch-shortening cycle probably lead to a higher Entinostat maximal KAV (Kellis and Katis, 2007; Kellis et al., 2006) which is transmitted to the ankle and finally to the toe and increases ball speed (Asami and Nolte, 1983). Consequently, any changes observed after stretching should be related to some or all the aforementioned factors. In the present study, quadriceps muscle EMG (Figure 3) remained unaltered while angular and ball speed kinematics decreased after static stretching.

When STRO-1A cells had reached confluence, they were detached wit

When STRO-1A cells had reached confluence, they were detached with trypsin-ethylenediamine leave a message tetra-acetic acid (trypsin-EDTA, Sigma-Aldrich T4049), counted and re-suspended in culture medium (Iscove��s medium (Sigma-Aldrich I3390) with L-glutamine (Sigma-Aldrich G7513) containing 10% fetal bovine serum (VWR BWSTS1810/100), 100 U/mL penicillin G (Sigma-Aldrich P3032), 100 ��g/mL streptomycin sulfate (Sigma-Aldrich S9137) and 10?8 M dexamethasone (Sigma-Aldrich D4902). Inoculation of scaffolds and static culture The sterilised scaffolds were rehydrated with complete cell culture medium for 24 h before cell culture. After this period, STRO-1A cells were seeded onto the porous scaffolds by adding 50 ��L of cell suspension media to scaffolds (seeding density 5 �� 105 cells/scaffold), placed in 24-well culture plates and incubated for 30 min in an incubator.

Thereafter, 2 mL of Iscove��s medium was slowly added to each well and STRO-1A cells were incubated in a humidified atmosphere at 37��C and 5% CO2 for 24 h (to allow the initial cellular attachment on the scaffolds). The inoculated scaffolds were further cultured under static condition for 24 h and 3, 7, 14 and 21 d in a humidified incubator at 37��C and 5% CO2. The medium was renewed three times per week. Dynamic cultures The dynamic culture condition was applied within perfusion bioreactors supplied by Minucells and Minutissue? (Bad Abbach, ref. 1307). This perfusion system, which allows perfusion of up to six scaffolds in parallel depending on their size, is connected to an open circuit meaning that the container is connected to a medium bottle (input) and to a waste reservoir (output) by gas-permeable silicon tubes.

The STRO-1A cells seeded on the HA-Col scaffolds were maintained for 24 h in static condition to allow total cell adhesion. Then, samples were placed in the perfusion container within which they were separated by support rings and cultured for 1, 3, 7, 14 and 21 d at a temperature of 37��C and a carbon dioxide concentration of 5%. Only three samples were put in each bioreactor considering their size and to reduce the risk of hypoxia. Two constant flow perfusion rates at 0.03 (2) and 0.3 mL/min (20 mL/h)�Dlow and high flow-rate respectively�Dwere applied (Fig. 8A). For the low flow, the open circuit was maintained although it was closed for the high flow due to medium cost (Fig.

8B,C). In the low-flow condition, 250 mL of medium circulated in the bioreactor and was renewed every three/four days while in the high-flow condition, 250 mL of medium circulated in the bioreactor and was renewed every seven days. Cultures were maintained for up to 21 d. Figure 8. Schematic GSK-3 diagram of three HA-Col scaffolds submitted to two dynamic environments within the perfusion bioreactor (A). Scheme of the open circuit with low flow-rate (0.03 mL/min); (B) and the closed circuit with high flow-rate (0.3 mL/min); …

Figure 4 Mean workload and standard deviation in milliseconds (ms

Figure 4 Mean workload and standard deviation in milliseconds (ms), thru the Mixed Effect Model, for each exercise. Vastus Medialis (VM), Vastus Lateralis (VL) and Gluteus Medius (GM). Table 1 Mean (SD) ��T2 in milliseconds (ms) during each intervention and selleck inhibitor mean difference (95% CI) between exercises for each muscle Discussion The use of MRI to quantify muscle function has been extensively investigated in the last three decades, but the exact mechanism for changes in T2 is not known (Saab et al., 2000). In principle, many factors could contribute, including increase in intracellular and extracellular water content, accumulation of diamagnetic ions (eg. lactate, phosphate, sodium) and decrease in pH (Jenner et al., 1994; Meyer and Prior, 2000).

Some authors had demonstrated a direct relationship of the increase in T2 with the muscle perfusion and volume, but Prior et al. (2001) had documented the increase of T2 in rat muscle even with the occlusion of the vein and electric stimulation (Ploutz-Snyder et al., 1997). Although Cheng et al. (1995) observed that the recovery of muscle pH after exercise is faster than the recovery of T2. The Relaxometry method had good applicability, as demonstrated by Yue et al. (1994), only five repetitions of arm curl with a load of 25% of 1 Repetition Maximum were enough to increase the T2 of the short head of biceps brachii, thus proving the sensitivity of the method. In the same way Adams et al. (1992) could find differences in the increase of the T2 of the concentric and eccentric muscle contraction.

Previous studies provided evidence of a linear association between the ��T2 and the exercise intensity suggesting an index of muscle workload (Yue et al., 1994; Meyer and Prior, 2000). Based in those reports and in our data, it is possible to suggest the type of squat exercise that optimally workload the muscles responsible for stabilizing the patellofemoral joint and the knee dynamic Q angle. The squat exercise presented a significant higher workload of vastus medialis in relation to vastus lateralis, suggesting that the squat exercise presented less risk of patellofemoral maltracking among the 3 squats used in this work. The hypothesis that the contraction of the hip adductor muscles would favor the vastus medialis in the squat associated with isometric hip adduction exercise was not confirmed by our data.

There was no workload difference between vastus medialis and vastus lateralis, suggesting that squat associated with isometric hip adduction does not selectively recruit the vastus medialis muscle. But our hypothesis that the gluteus medius workload decrease with the association of isometric hip adduction was confirmed. Squat associated with isometric hip abduction was the only exercise that presented a balance of vastus medialis, vastus lateralis and gluteus Cilengitide medius muscles, despite a gluteus medius workload similar to squat exercise.