Intramuscular Temperature Changes in the Quadriceps Femoris Muscle After Post-Exercise Cold-Water Immersion (10°C for 10 min): A Systematic Review With Meta-Analysis

Post-exercise cold-water immersion (CWI) is a widely accepted recovery strategy for maintaining physical performance output. However, existing review articles about the effects of CWI commonly pool data from very heterogenous study designs and thus, do rarely differentiate between different muscles, different CWI-protocols (duration, temperature, etc.), different forms of activating the muscles before CWI, and different thickness of the subcutaneous adipose tissue. This systematic review therefore aimed to investigate the effects of one particular post-exercise CWI protocol (10°C for 10 min) on intramuscular temperature changes in the quadriceps femoris muscle while accounting for skinfold thickness. An electronic search was conducted on PubMed, LIVIVO, Cochrane Library, and PEDro databases. Pooled data on intramuscular temperature changes were plotted with respect to intramuscular depth to visualize the influence of skinfold thickness. Spearman's rho (rs) was used to assess a possible linear association between skinfold thickness and intramuscular temperature changes. A meta-analysis was performed to investigate the effect of CWI on pre-post intramuscular temperature for each measurement depth. A total of six articles met the inclusion criteria. Maximum intramuscular temperature reduction was 6.40°C with skinfold thickness of 6.50 mm at a depth of 1 cm, 4.50°C with skinfold thickness of 11.00 mm at a depth of 2 cm, and only 1.61°C with skinfold thickness of 10.79 mm at a depth of 3 cm. However, no significant correlations between skinfold thickness and intramuscular temperature reductions were observed at a depth of 1 cm (r s = 0.0), at 2 cm (r s = -0.8) and at 3 cm (r s = -0.5; all p > 0.05). The CWI protocol resulted in significant temperature reductions in the muscle tissue layers at 1 cm (d = -1.92 [95% CI: -3.01 to -0.83] and 2 cm (d = -1.63 [95% CI: -2.20 to -1.06]) but not at 3 cm (p < 0.05). Skinfold thickness and thus, subcutaneous adipose tissue, seems to influence temperature reductions in the muscle tissue only to a small degree. These findings might be useful for practitioners as they demonstrate different intramuscular temperature reductions after a specific post-exercise CWI protocol (10°C for 10 min) in the quadriceps femoris muscle. Keywords: adipose tissue; cold-water immersion; exercise; intramuscular temperature; metabolism

Changes in balance coordination and transfer to an unlearned balance task after slackline training: a self-organizing map analysis

How humans maintain balance and change postural control due to age, injury, immobility or training is one of the basic questions in motor control. One of the problems in understanding postural control is the large set of degrees of freedom in the human motor system. Therefore, a self-organizing map (SOM), a type of artificial neural network, was used in the present study to extract and visualize information about high-dimensional balance strategies before and after a 6-week slackline training intervention. Thirteen subjects performed a flamingo and slackline balance task before and after the training while full body kinematics were measured. Range of motion, velocity and frequency of the center of mass and joint angles from the pelvis, trunk and lower leg (45 variables) were calculated and subsequently analyzed with an SOM. Subjects increased their standing time significantly on the flamingo (average +2.93 s, Cohen’s d = 1.04) and slackline (+9.55 s, d = 3.28) tasks, but the effect size was more than three times larger in the slackline. The SOM analysis, followed by a k- means clustering and marginal homogeneity test, showed that the balance coordination pattern was significantly different between pre- and post-test for the slackline task only (χ2 = 82.247; p 0.001). The shift in balance coordination on the slackline could be characterized by an increase in range of motion and a decrease in velocity and frequency in nearly all degrees of freedom simultaneously. The observation of low transfer of coordination strategies to the flamingo task adds further evidence for the task-specificity principle of balance training, meaning that slackline training alone will be insufficient to increase postural control in other challenging situations

DOI:10.1068/htwu154 Measurement of the thermal diffusivity by the laser-flash

method with repeated pulse

DOI:10.1068/htwu184 An estimation of thermophysical properties of layered materials by the laser-flash method

Abstract. An investigation of two-layered and three-layered systems by the flash method has been carried out. Because of the behaviour of the material analysed, the theory considers twolayered and three-layered composites with the ideal thermal contact described by zero thermal contact resistance. The data reduction algorithm is introduced and results are given of an estimation of the thermal diffusivity of alumina (aluminium oxide, Al 2O 3) on copper/alumina layers. An estimation of the thermal diffusivity of one layer requires, besides the knowledge of other relevant properties (density, heat capacity, and thickness of components), knowledge of the thermal diffusivity of the remaining layer(s). The way the error in the known thermal diffusivity influences the error in the unknown thermal diffusivity estimation is analysed. The proposed approach, which indicates error propagation and estimates the accuracy limits, is applied to a two-layered system.

Entwicklung und Einsatzverhalten von aktiv gekühlten Testlimitern für das Fusionsexperiment TEXTOR

To investigate aspects of the plama-wall-interaction in fusion devices, TEXTOR ($\underline{T}$oroidal$\underline{E }$xperiment for $\underline{T}$echnology $\underline{O}$rientated $\underline{R}$esearch) provides a favourable testbed. The enhanced possibilities of TEXTOR-94 enable to study typical erosion- and redeposition phenomena on plasma exposed surfaces under stationary, technology relevant conditions. For these purposes actively cooled test limiters are developed and described in their experimental behaviour. Compared to the maximum length of plama discharges in TEXTOR of 10 s, these limiters reach a stationary state within 5,5 s. The detailed analysis of the thermal load conditions led to an optimized geometry of the test limiters. The use of the new load lock system "TEXTOR-Schleuse-III" limits the maximum diameter of the inserted structures to 120 mm. Both, the heat load distribution at the limiter surface and the restrictions of the load lock system, led to the selection of a hemispherical shape with a maximum diameter of 80 mm at the top of the test limiters. They where realized in two technological variants. The first variant was a brazed compound of a metallic heat sink (TZM) with carbon materials as the two directional C/C material SEPCARB-N11 or the fine grain graphite IG 610. The second one was a TZM heat sink, coated with thermally sprayed tungsten. The choosen braze was CulCr. The used thermal spray technology was LPPS ($\underline{L}$ow $\underline{P}$ressure $\underline{P}$lasma $\underline{S}$praying). For the analysis of the thermomechanical conditions in the joined hemispherical test limiter, analytical as well as numerical estimations of the transient spatial tempmeratures were done. Both methods predicted a stationary temperature on the C/C surface is 1150$^{\circ}$ C. In the joining zone 630 $^{\circ}$ C. are reached, at the cooling surface 220 $^{\circ}$ C. For the coated test liiter the calculations predicted stationary conditions after 2 s and a maximum hot spot temperature of 550 $^{\circ}$ C. A qualitative, numerical analysis of the von Mises equivalent stress was done for the C/C-TZM brazing compound. In the hot spot zone moderate stress levels as weIl as stress amplitudes appear. Maximum stress levels and stress amplitudes were predicted in the equatorial area of the hemispherical test limiter. Stress levels in the TZM structure are approximately four times higher than in the carbon materials. Mismatches in the elastomechanical properties of the joining partners locally generate high stress levels. They were reduced by the use of the ductile Cu1Cr braze and an optimized interface design. High heat flux tests with prototype test limiters in the ion beam test facility MARION($\underline{M}$aterial $\underline{R}$esearch $\underline{I}$on Beam Test Facility) confirmed the calculated cooling behaviour and the application reliability of the components under high vacuum conditions and high heat loads. An optimized brazed test limiter was inserted in TEXTOR for 101 plasma discharges. Experimental results with heat loads of up to 12 MW/m$^{2}$ are in excellent agreement with the mathematical models and confirmed the structural integrity of the joined structure. Physical and chemical erosion of carbon from the limiter surface could be observed. Erosion and redeposition phenomena led to an optical change of the C/C surface, but no significant loss of C/C material was detectable

Intercomparison of thermal diffusivity measurements on CuCrZr and PMMA

The results of an inter laboratory comparison of thermal diffusivity measurements on two different materials, namely a copper alloy (CuCrZr) and a polymer (PMMA), are presented here. Both materials were selected with respect to their different thermal conductivity, since the copper alloy belongs to the family of good metallic conductors whereas the polymer is characterized by a low thermal conductivity. The measurements of the thermal diffusivity have been performed within a temperature range from RT to 500°C for the copper alloy and from RT to 100°C for the PMMA, respectively