Reliability of the parameters of the power-duration relationship using maximal effort time-trials under laboratory conditions

The purpose of this study was to assess the reliability of critical power (CP) and the total amount of work accomplished above CP (W´) across repeated tests using ecological valid maximal effort time-trials (TTs) under laboratory conditions. After an initial incremental exercise test, ten well-trained male triathletes (age: 28.5 ± 4.7 yrs; body mass: 73.3 ± 7.9 kg; height: 1.80 ± 0.07 m; maximal aerobic power (MAP): 328.6 ± 41.2 W) performed three testing sessions (Familiarization, Test I and Test II) each comprising three TTs (12 min, 7 min and 3 min with a passive recovery of 60 min between trials). CP and W´ were determined using a linear regression of power vs. the inverse of time (1/t) (P = W´ ∙ 1/t + CP). A repeated measure ANOVA was used to detect differences in CP and W´ and reliability was assessed using the intra-class correlation coefficient (ICC) and the coefficient of variation (CoV). CP and W´ values were not significantly different between repeated tests (P = 0.171 and P = 0.078 for CP and W´, respectively). The ICC between Familiarization and Test I was r = 0.86 (CP) and r = 0.58 (W´) and between Tests I and II it was r = 0.94 (CP) and r = 0.95 (W´). The CoV notably decreased from 4.1% to 2.6% and from 25.3% to 8.2% for CP and W´ respectively. Despite the non-significant differences for both parameter estimates between the repeated tests, ICC and CoV values improved notably after the Familiarization trial. Our novel findings indicate that for both, CP and W´ post familiarization ICC and CoV values indicated high reliability. It is therefore advisable to familiarize well-trained athletes when determining the power-duration relationship using TTs under laboratory conditions

Different durations within the method of best practice affect the parameters of the speed-duration relationship

The aim of the study was to determine whether estimates of the speed-duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2 to 15 min. Ten triathletes (mean±SD age: 31.0±5.7yrs; height: 1.81±0.05m; body mass: 76.5±6.8kg) performed two randomly assigned field-tests to determine critical speed (CS) and the total distance covered above CS (D´). CS and D´ were obtained using two different protocols comprising three TT that were interspersed by 60 min passive rest. The TTs were 12, 7, and 3 min in Protocol I and 10, 5, and 2 min in Protocol II. A linear relationship of speed vs. the inverse of time (s=D´x1/t+CS) was used to determine parameter estimates. Significant differences were found for CS (P=.026), but not for D´ (P=.123). The effect size for CS (d=.305) was considered small, whilst that for D´ was considered moderate (d=.742). CS was significantly correlated between protocols (r=.934; P<.001), however, no correlation was found for D´ (r=.053; P=.884). The 95% limits of agreement were ±0.28m∙s-1 and ±73.9m for CS and D´, respectively. These findings demonstrate that the choice of exhaustive times within commonly accepted durations, results in different estimates of CS and D´ and thus protocols cannot be used interchangeably. The use of a consistent protocol is therefore recommended, when investigating or monitoring the speed-duration relationship estimates in well-trained athletes

TBK1 is part of a galectin 8 dependent membrane damage recognition complex and drives autophagy upon Adenovirus endosomal escape.

Intracellular pathogens cause membrane distortion and damage as they enter host cells. Cells perceive these membrane alterations as danger signals and respond by activating autophagy. This response has primarily been studied during bacterial invasion, and only rarely in viral infections. Here, we investigate the cellular response to membrane damage during adenoviral entry. Adenoviruses and their vector derivatives, that are an important vaccine platform against SARS-CoV-2, enter the host cell by endocytosis followed by lysis of the endosomal membrane. We previously showed that cells mount a locally confined autophagy response at the site of endosomal membrane lysis. Here we describe the mechanism of autophagy induction: endosomal membrane damage activates the kinase TBK1 that accumulates in its phosphorylated form at the penetration site. Activation and recruitment of TBK1 require detection of membrane damage by galectin 8 but occur independently of classical autophagy receptors or functional autophagy. Instead, TBK1 itself promotes subsequent autophagy that adenoviruses need to take control of. Depletion of TBK1 reduces LC3 lipidation during adenovirus infection and restores the infectivity of an adenovirus mutant that is restricted by autophagy. By comparing adenovirus-induced membrane damage to sterile lysosomal damage, we implicate TBK1 in the response to a broader range of types of membrane damage. Our study thus highlights an important role for TBK1 in the cellular response to adenoviral endosome penetration and places TBK1 early in the pathway leading to autophagy in response to membrane damage

The comparison of maximal and endurance strength of quadriceps femori in trained and untrained elderly

The purpose of this study was to examine the differences in knee extensor maximal and endurance strength in elderly. Sixteen healthy elderly served as subjects, eight of them trained , age 61.0±8.9 yrs; height, 170.6±6.8 cm; weight, 71.8±11.7 kg [mean ± standard deviation] and eight untrained 61.4±8.1 yrs, height 174.6±7.4 cm; weight 83.9 ±14.2 kg. Maximal strength in single leg extension exercise was measured unilaterally with the dominant leg until the subjects reached their 1 Repetition Maximum (RM) covering the full Range of Motion (ROM). Muscular endurance was obtained with a load of 75% of 1-RM for 3 consecutive sets, with 2 min rest periods till failure. Load at 1 RM was lower in absolute terms in untrained, but not significant, while the relative 1-RM test was significantly lower in untrained subjects (0.20 vs. 0.25 kg load/kg body weight) (p<0.05). The number of repetitions and amount of weight lifted performed of all 3 sets was higher in trained subjects, but not significant. In the trained group both repetitions and the load managed in the third set was significant lower compared with the first two sets. The result that maximal force output is more affected compared to muscular endurance in these subjects might be due to the habitual use of quadriceps femoris muscles during activity of daily living in both trained and untrained elderly

The Enjoyability of Physical Exercise: Exergames and Virtual Reality as New Ways to Boost Psychological and Psychosocial Health in Astronauts. A Prospective and Perspective View

On Earth, physical activity plays a tremendous role to preserve and improve the physical, psychological, and social well-being of people. The enjoyability, the appreciation, and the variability of the exercises are fundamental factors for the production of lifestyle benefits. Currently, exercise countermeasures for astronauts during long-duration missions focus more on the physiological side, frequently overlooking the relevant psychosocial one. Exergames are a form of physical activity that have taken hold in the last decades on Earth and has been widely accepted as a more enjoyable and engaging rehabilitation, reconditioning, and training tool compared to the previous conventional ones. After a review of the current needs of astronauts and of the positive effects of exergames on people on Earth, we suggest that exergaming should be implemented in space missions to improve physical, psychological, and social well-being of astronauts. We also propose practical methods on how exergames can be effectively implemented

A Video-Based Tactical Task Does Not Elicit Mental Fatigue and Does Not Impair Soccer Performance in a Subsequent Small-Sided Game

Mental fatigue can impair physical, technical, and tactical performance in sports. Since most previous research used general cognitive tasks to elicit mental fatigue, the aim of this study was to investigate whether a more sport-specific task could induce the effects of mental fatigue and impair the subsequent physical and technical performance in a soccer small-sided game. Ten soccer players performed two small-sided games on two different days in a crossover design. Before each small-sided game, they performed a video-based tactical task (30 min) and a control task (documentary watching, 30 min) in a randomized and counterbalanced order. Mental effort was measured through a visual analog scale after the tactical and control tasks. Subjective ratings of perceived exertion were assessed through the RPE questionnaire after the end of the SSG. Physical performance was assessed during the SSG through GPS technology. Results showed no differences (p &gt; 0.05) in physical performance between the two conditions. None of the technical variables were negatively affected by the video-based tactical condition, with the number of total passes (p = 0.003; ES = 0.72 medium) and successful passes (p = 0.003; ES = 0.82 large) results even improved by the video-based tactical task. The mental effort required by the video-tactical task was significantly higher than the control task (p = 0.002; ES = 2.09 huge). However, overall RPE did not differ between conditions. The video-based tactical task did not elicit mental fatigue and did not impair subsequent physical and technical performance. The higher ecological validity of the task and the higher motivation of the participants might have contributed to the results

Belastungs Beanspruchungsprofil im Fussball aus physiologischer Sicht

Contains fulltext : mmubn000001_215791673.pdf (publisher's version ) (Open Access)Promotor : K. WellensXV, 396 p

Lacrosse Athletes Load and Recovery Monitoring: Comparison between Objective and Subjective Methods

Both objective (OM) and subjective (SM) methods are used in athletic studies, regardless of sport type, to identify and analyze load and recovery status of athletes. As little information exists about the comparison of these two methodologies, the aim of this study is to compare and contrast information that defines the relationship between both methods. Twelve international male lacrosse athletes participated in this study over the course of which participants heart-rate-variability and questionnaire-data were collected. Statistical analysis was performed to evaluate changes over time and correlations between used methods. Comparison between baseline values and competition showed a reduction in root-mean-square of successive differences (RMSSD) (p &lt; 0.01) and the proportion of beat-intervals (NN) that differ by more than 50 ms divided by total number of NNs (pNN50) (p &lt; 0.01). Further, RMSSD values showed differences during competition with large effects (p = 0.02; &eta;2 = 0.24). SM (p &lt; 0.01) showed different progression during competition. Correlation was found for used SM and OM, when considered separately. No evidence for a reliable prediction of OM values using SM could be found. According to these findings, we recommend using a combination of SM and OM data to quantify the physiological stress of training and competition, respectively

The penalty kick accuracy in soccer: A new biomechanical approach

The purpose of this study was to present a practical novel method to calculate the penalty kick accuracy in football. The mathematical advantage considered the ratio of the rectangle goal dimension (1:3) and equalized between horizontal axis as it longer 3 times than the vertical axis. Twelve male soccer players 16 (3) years)), height 174.7 (4.5) cm)), body mass 67.6 (5.5) kg)) volunteered to participate in this study. The players were asked to do penalty kicks where the ball is aimed at the farthest point from the centre of the target portion for shooting. The soccer goal was split into quarters at three different velocities (low, medium, and high) the calculation was conducted two times by height to width ratio (HWR) and the most common method radial error. Kinovea Software 0.8.27. were used for digitizing. The ICC demonstrated high reliability (r = .99) for digitization at the moment the ball crossed the goal line for the inter and intra-ratter reliability. There was a significant relationship between some kinematics variables of the ball and the accuracy outcome of the HWR method in the four sections of the goal (p < .05)