Improving the measurement of TMS-assessed voluntary activation in the knee extensors

The present study was designed to test the accuracy, validity, reliability and sensitivity of the main outcomes of alternative methods for the measure of TMS-assessed voluntary activation (VATMS) in the knee extensors. Ten healthy recreationally active males (24 ± 5 years) completed a neuromuscular assessment protocol (NMA) before and immediately after a fatiguing isometric exercise, consisting of two sets of five contractions (50%, 62.5%, 75%, 87.5%, and 100% of Maximal Voluntary Contraction; MVC) with superimposed TMS-evoked twitches (SITs) for calculation of VATMS (1x5C vs. 2x5C). The protocol was performed on two separate occasions for the measurement of between-day reliability. Where deemed appropriate, comparisons were made with a routinely used protocol [i.e. 50%, 75%, and 100% of MVC (1x3C) performed three times (3x3C)] from re-analysed data (Dekerle et al., 2018). Confidence intervals for the measure of a key determinant of VATMS (estimated resting twitch) were similar between 1x5C and 2x5C but improved by six-fold when compared to 1x3C (P<0.05). Potentiated twitch force evoked via percutaneous electrical stimulation of the femoral nerve was unchanged from pre- to post-NMA at baseline for 1x5C (P>0.05) but decreased for 2x5C and 3x3C (P<0.05). Its recovery post-exercise was lesser for 1x5C compared to 2x5C and 3x3C (P<0.05), with no difference between the latter two (P>0.05). Absolute reliability was strong enough for both 1x5C and 2x5C to depict a true detectable change in the sample’s VATMS following the fatiguing exercise (TEM < 3% at rest, <9% post-exercise) but 2x5C was marginally more sensitive to individual’s changes at baseline. In conclusion, both 1x5C and 2x5C provide reliable measures of VATMS. However, the 1x5C protocol may hold stronger internal validity.

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The AccuKick football passing test: Reliability, discriminate ability, and correlations with athletic capabilities

AccuKick is a new football passing test that measures passing accuracy and time to ball release (TTR) under time constrains. We examined AccuKick’s test-retest reliability, discriminate ability, and its relationships with jumping, sprinting, change-of-direction and intermittent running tests, among adolescent football players. Forty-seven players of different age groups participated in this study: U19 (n = 15), U17 (n = 15) and U16 (n = 17). Athletes completed two trials of AccuKick on two different days. Test-retest reliability of accuracy and TTR outcomes were very high (r = 0.85) and moderately high (r = 0.66), respectively. Accuracy scores significantly differed between groups (p < 0.001) with the U19 players being more accurate than the U17 (8%) and the U16 (22%) players. TTR scores significantly differed between groups (p = 0.005) with U19 releasing the ball 0.005 seconds faster than U17 (g = 1.3) but with no other statistical differences between groups. Trivial to small correlations (r ≤ 0.25) were observed between AccuKick performance and the physical tests, excluding the Yo-Yo test which was weakly correlated with accuracy and TTR (p ≤ 0.01; r range: 0.35-0.48). AccuKick is a reliable passing test that can distinguish between adolescent players according to their age.

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Perceived Impact: A Mechanism Underpinning the End-Spurt and U-Shape Pacing Patterns

The end-spurt and U-shape reflect common pacing patterns across numerous fields. To date, however, the literature lacks a parsimonious, applicable account for these effects. Here, I propose a novel causal explanation for these effects – perceived impact. As one perceives his/her actions to better affect progress within a task, the higher one’s motivation. The higher one’s motivation in a given time, the better his/her performance. To illustrate, during a race, if an athlete has five more laps to go, completing a given lap closes 20% of the remaining distance (1/5 laps = 20%). Alternatively, when the athlete has two laps to go, each lap represents 50% of the remaining distance. In the latter case, the impact of completing a single lap on goal progress is perceived to be higher. Accordingly, his/her motivation will increase near the end – giving rise to an end-spurt. I exemplify through simulations how this model can account for previous racing and research outcomes observing end-spurts and U-shaped pacing patterns. In addition to being theoretically insightful, this framework offers practical field implications for coaches and athletes by modifying counting style within sets (e.g., “3, 2, 1” instead of “13, 14, 15”), session outline (e.g., challenging sets in the end, instead of in the middle of the session), etc.

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The Effect of Narcissistic Admiration and Rivalry on Mental Toughness in Thai Athletes

Objective. Are narcissistic athletes mentally tough? Despite the existing literature supporting the view that narcissistic grandiosity is positively related to mental toughness, no efforts have been made to understand how the agentic and antagonistic sides of narcissism are associated with mental toughness. Here we examine the effect of narcissistic admiration and rivalry on self-reported and behavioural mental toughness. Based on the different cognitive-affective-motivational pathways associated with admiration and rivalry, we hypothesized that the agentic side of narcissism (i.e., admiration) would predict greater mental toughness, whereas the antagonistic dimension of narcissism would be negatively related to mental toughness. Method. A sample of 276 elite Thai athletes completed self-report measures of narcissistic admiration and rivalry, self-esteem and mental toughness. Informant ratings of mentally tough behaviour were provided by coaches (n = 19) for a subset of athletes (n = 119). Results. Narcissistic admiration was positively associated with self and coach-ratings of mental toughness; in contrast, narcissistic rivalry was negatively associated with self and coach-ratings of mental toughness. These effects were independent of self-esteem. Conclusion. The findings stress the importance of considering the effects of different dimensions of narcissism and, contrary to previous evidence, suggest that narcissism is not universally predictive of heightened mental toughness.

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Dose response association of objective physical activity with mental health in a representative national sample of adults: a cross-sectional study

Although higher physical activity (PA) levels are associated with better mental health, previous findings about the shape of the dose–response relationship between PA and mental health are inconsistent. Furthermore, this association may differ according to sedentary levels. We investigated the cross-sectional dose-response associations between objectively measured PA and mental health in a representative national sample of adults. We also examined whether sedentary time modified the PA – mental health associations. Based on 2007-2013 Canadian Health Measures Survey data, PA and sedentary time were measured using accelerometry among 8150 participants, aged 20 to 79 years. Generalized additive models with a smooth function were fitted to examine associations between minutes per day of moderate and vigorous PA (MVPA), light PA (LPA), daily steps (combined or not with sedentary time) and self-rated mental health. A significant curvilinear relationship between average daily minutes of MVPA and mental health was observed, with increasing benefits up to 50 minutes/day. For LPA, a more complex shape (monotonic and curvilinear) was found. For daily steps, inverted U-shaped curve suggested increasing benefits until a plateau between 5000 and 16000 steps. The MVPA-LPA combination was significantly associated with mental health but with a complex pattern. The tested PA-sedentary time combinations showed that increasing sedentary time decreased the positive PA-mental health associations. Non-linear dose-response patterns between the PA modalities and self-reported mental health were observed. Optimal doses of daily minutes of MVPA, LPA, MVPA combined with LPA and daily steps are independently associated with better mental health in adults. The results also suggest that PA-mental health associations could be hampered by daily sedentary time.

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Exercise practice associates with different brain rhythmic patterns during vigilance

Purpose: To investigate brain oscillatory patterns underlying prolonged attentional performance as a function of cardiorespiratory fitness in healthy young adults. Design: Cross-sectional study. Method: Two groups of participants (25 higher-fit and 25 lower-fit) were compared in terms of reaction time (RT) performance, tonic electroencephalographic (EEG) overall dynamics, and event-related spectral perturbation (ERSP) in a 60’ version of the psychomotor vigilance task. Resting state EEG was also measured. A submaximal cardiorespiratory fitness test confirmed the between-groups difference in terms of aerobic fitness. Results: Descriptive behavioural data showed shorter RTs in higher-fit participants, but only during the first 30’ of the task. Crucially, this same period was accompanied by increased theta (4-8 Hz) and upper beta (20-40 Hz) power and reduced alpha (8-14 Hz) and lower beta (14-20 Hz) suppression after the target stimulus presentation compared to their lower-fit peers, but these differences disappeared in the second part of the task. Additionally, lower-fit showed greater suppression of upper beta power than higher-fit after the cue stimulus presentation, an effect that was not modulated by the time-on-task. EEG overall dynamics results did not show significant differences between groups, although they also evidenced interesting differential brain oscillatory patterns as a function of aerobic fitness both at rest and during task performance. Conclusions: Cardiorespiratory fitness was related to a brain oscillatory differential response pattern over a wide range of the frequency spectrum and spatio-temporal distribution, which seems to underlie the positive association between aerobic fitness and sustained attention.

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Mechanical Misconceptions: Have we lost the “mechanics” in “biomechanics”?

In theory, everything in biomechanics stems from two disciplines, physics and biology. While a number of papers, editorials, letters to the editor, and even a review have addressed the misapplication of mechanical principles, the misapplication of the basic principles of physics in the field of biomechanics continues. There are three principles, specifically, that have been misapplied that we address: 1) reaction forces as they pertain to joint reaction forces; 2) the treatment of scalar quantities with direction; and 3) the terms weightlessness, microgravity, hypergravity, and unweighted.

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Objectively measured physical activity and sedentary behaviors in a representative sample of Canadian adults with chronic disease(s) : a cross-sectional study

Background: Physical activity and sedentary behaviors are major determinants of quality of life in adults with one or more chronic disease(s). However, there are no Canadian representative population-based studies investigating objectively measured physical activity and sedentary behaviors in adults with and without chronic disease(s). Objective: To compare objectively measured physical activity and sedentary behaviors in a representative sample of Canadian adults with and without chronic disease(s). Methods: Data were obtained from the Canadian Health Measure Survey (CHMS) (2007-2013). Physical activity and sedentary behaviors were measured using accelerometry in Canadians aged between 35 and 79 years. Data are characterized as daily mean time spent in moderate to vigorous physical activity (MVPA), light physical activity (LPA), and sedentary behavior, as well as steps accumulated per day. Chronic diseases (chronic obstructive pulmonary disease, diabetes, heart diseases, cancer) were assessed via self-report diagnostic or laboratory data. Four weighted multivariable analyses of covariance comparing physical activity and sedentary behavior variables among adults without and with one or more chronic diseases were conducted. Results: In the total, 6270 CHMS participants were included. Analyses indicated that 23.9%, 4.9% and 0.5% had one, two, and three or more chronic diseases. Adults with two or three and more chronic diseases had significantly lower daily duration of MVPA and LPA, lower daily step counts, and higher daily duration of sedentary behavior compared to adults with no chronic diseases, with low effect sizes. Conclusions: Canadian multimorbid adults might benefit from targeted interventions to increase physical activity and reduce sedentary behaviors.

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Examining the influence of skin tone on playing position in the Premier and English Football Leagues

Within the present manuscript we explore the role of skin tone on playing position within English football’s top four professional leagues. Player data (N = 4,515) was collected across five seasons (2010-2015). Results indicate that in general, darker skin toned players are more likely to operate within peripheral rather than central positions. Using both one and two-way ANOVAs, results suggest significant differences between skin tone and individual playing positions. Between league differences were, however, non-significant. Although darker skin toned players are still more likely to occupy peripheral positions, the situation is more nuanced than first thought. Instead of segregating players by central versus peripheral roles, it appears that darker skin toned players occupy positions associated with athleticism. In contrast, lighter skin toned players appear to fulfil roles requiring organization and communication skills.

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Daily objective physical activity and sedentary time in adults with COPD using spirometry data from Canadian Measures Health Survey

Chronic obstructive pulmonary disease (COPD) is expected to be the third leading cause of premature death and disability in Canada and around the world by the year 2020. The study aims to compare objective physical activity (PA) and sedentary time in a population-based sample of adults with chronic obstructive pulmonary disease (COPD) and comparison a group, and to investigate whether these behaviors differ according to COPD severity. Methods From the 2007-2013 Canadian Health Measures Survey dataset, accelerometer and pre-bronchodilator spirometry data were available for 6441 participants, aged 35 to 79. Two weighted analyses of covariance were performed with adjustments for age, sex, body mass index, accelerometer wearing time and season, work, smoking (cotinine), education level and income. A set of sensitivity analyses were carried out to examine the possible effect of COPD, and type of control group. Results A cross-sectional weighted analysis indicated that 14,6% of study participants had a measured airflow obstruction consistent with COPD. Time in PA (moderate-vigorous and light PA), number of steps and sedentary duration were not significantly different in participants with COPD, taken together, compared to controls. However, moderate to severe COPD participants (stages ≥2) had a significantly lower daily time spent in PA of moderate and vigorous intensity level compared to controls. Conclusions Canadian adults with COPD with all disease severity levels combined did not perform lower daily duration of light, moderate and vigorous PA, number of steps and higher daily sedentary time than those without airflow obstruction. Both groups are extremely sedentary and have low PA duration. Thus, “move more and sit less” public health strategy could equally target adults with or without COPD.

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