How Much Training Is Too Much?

2017 ◽  
Vol 32 (1) ◽  
pp. 61-62 ◽  
Author(s):  
Bronwen J Ackermann
Keyword(s):  
Approximate Determination ◽  
International Studies ◽  
Common Causes ◽  
Or Practice ◽  
Performance Domains ◽  
Underlying Mechanisms ◽  
Rest Breaks ◽  
Performing Artist ◽  
Musculoskeletal Performance

Managing training practices in elite performance domains is recognised to play an important role in preventing musculoskeletal overload, and hence reducing the risk of overuse-related injuries. In international studies spanning four decades, the duration of playing, especially in combination with sudden increases in playing and inadequate rest breaks, remains one of the most common causes of injuries. With musculoskeletal performance in occupational and sports domains, both the work:rest ratio and the acute:chronic workload ratio are considered critical in making an approximate determination in the length of training sessions. However, there are many complex underlying mechanisms that interact with the duration of training and how long a performing artist may safely rehearse or practice. Instead of trying to set rigid timelines, particularly for personal practice/training, recognising mental and physical signs of fatigue may be more useful to inform the performing artist when to stop and rest rather than to persist.

scholarly journals MANAGEMENT OF ENDOCRINE DISEASE: Secondary osteoporosis: pathophysiology and management

2015 ◽  
Vol 173 (3) ◽  
pp. R131-R151 ◽  
Author(s):  
Faryal Mirza ◽  
Ernesto Canalis
Keyword(s):  
Bone Loss ◽  
Fragility Fractures ◽  
Low Bone Mass ◽  
Endocrine Disease ◽  
Skeletal Fragility ◽  
Increased Risk ◽  
Common Causes ◽  
The Common ◽  
Skeletal Disorder ◽  
Underlying Mechanisms

Osteoporosis is a skeletal disorder characterized by decreased mass and compromised bone strength predisposing to an increased risk of fractures. Although idiopathic osteoporosis is the most common form of osteoporosis, secondary factors may contribute to the bone loss and increased fracture risk in patients presenting with fragility fractures or osteoporosis. Several medical conditions and medications significantly increase the risk for bone loss and skeletal fragility. This review focuses on some of the common causes of osteoporosis, addressing the underlying mechanisms, diagnostic approach and treatment of low bone mass in the presence of these conditions.

scholarly journals Differentially altered Ca2+ regulation and Ca2+ permeability in Cx26 hemichannels formed by the A40V and G45E mutations that cause keratitis ichthyosis deafness syndrome

2010 ◽  
Vol 136 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Helmuth A. Sánchez ◽  
Gülistan Meşe ◽  
Miduturu Srinivas ◽  
Thomas W. White ◽  
Vytas K. Verselis
Keyword(s):  
Single Channel ◽  
Sensorineural Deafness ◽  
Cell Integrity ◽  
Extracellular Loop ◽  
Amino Terminal ◽  
Cysteine Substitution ◽  
Common Causes ◽  
Excessive Entry ◽  
Underlying Mechanisms ◽  
Pore Lining

Mutations in GJB2, which encodes Cx26, are one of the most common causes of inherited deafness in humans. More than 100 mutations have been identified scattered throughout the Cx26 protein, most of which cause nonsyndromic sensorineural deafness. In a subset of mutations, deafness is accompanied by hyperkeratotic skin disorders, which are typically severe and sometimes fatal. Many of these syndromic deafness mutations localize to the amino-terminal and first extracellular loop (E1) domains. Here, we examined two such mutations, A40V and G45E, which are positioned near the TM1/E1 boundary and are associated with keratitis ichthyosis deafness (KID) syndrome. Both of these mutants have been reported to form hemichannels that open aberrantly, leading to “leaky” cell membranes. Here, we quantified the Ca2+ sensitivities and examined the biophysical properties of these mutants at macroscopic and single-channel levels. We find that A40V hemichannels show significantly impaired regulation by extracellular Ca2+, increasing the likelihood of aberrant hemichannel opening as previously suggested. However, G45E hemichannels show only modest impairment in regulation by Ca2+ and instead exhibit a substantial increase in permeability to Ca2+. Using cysteine substitution and examination of accessibility to thiol-modifying reagents, we demonstrate that G45, but not A40, is a pore-lining residue. Both mutants function as cell–cell channels. The data suggest that G45E and A40V are hemichannel gain-of-function mutants that produce similar phenotypes, but by different underlying mechanisms. A40V produces leaky hemichannels, whereas G45E provides a route for excessive entry of Ca2+. These aberrant properties, alone or in combination, can severely compromise cell integrity and lead to increased cell death.

scholarly journals Causal Effects of Well-Being on Health: It's Complicated

2020 ◽  
Author(s):  
Julia Marie Rohrer ◽  
Richard E. Lucas
Keyword(s):  
Boundary Conditions ◽  
Experimental Studies ◽  
Well Being ◽  
Causal Effects ◽  
Subjective Well Being ◽  
Cross Sectional ◽  
Common Causes ◽  
Cast Doubt ◽  
Underlying Mechanisms ◽  
Main Effects

In positive psychology and well-being research, subjective well-being is frequently considered a cause of desirable outcomes, such as health. We discuss major conceptual complications that cast doubt on such claims. Well-being and health share a multitude of common causes, and neither cross-sectional, longitudinal, nor experimental studies can identify the effects of interest without strong assumptions that may be deemed implausible. We conclude that the field should rise to the causal inference challenge posed by understanding the main effects of well-being before moving on to more sophisticated claims concerning underlying mechanisms and boundary conditions.

Venous Pumps of The Hand

1996 ◽  
Vol 21 (5) ◽  
pp. 595-599 ◽  
Author(s):  
P. SIMONS ◽  
P. COLERIDGE SMITH ◽  
W. R. LEES ◽  
D. A. MCGROUTHER
Keyword(s):  
Muscle Contraction ◽  
Doppler Ultrasound ◽  
Venous Return ◽  
Venous Blood ◽  
Blood Velocity ◽  
Clinical Applications ◽  
Oedema Formation ◽  
Velocity Increase ◽  
Common Causes ◽  
Underlying Mechanisms

Oedema remains one of the most common causes of hand stiffness. Local venous return is intimately associated with oedema formation and management. To elucidate, the underlying mechanisms of venous return, the venous pumping systems in the hand were objectively and quantitatively investigated using Doppler ultrasound, cadaveric dissection and venography. It was demonstrated that functionally there are three independent venous systems: the superficial palmar, deep palmar and dorsal veins, which are activated by palm compression, isometric intrinsic muscle contraction, and dorsum compression, respectively. Each system was investigated independently and found to increase venous blood velocity in both the cephalic and ulnar veins. These systems were also shown to act in synergy, producing the greatest velocity increase when concurrently activated during fist-clenching. The volume of blood pumped during fist-clenching could also be potentiated by preloading by digit abduction. The clinical applications of these findings are discussed.

scholarly journals Sesamin: A Naturally Occurring Lignan Inhibits CYP3A4 by Antagonizing the Pregnane X Receptor Activation

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Yun-Ping Lim ◽  
Chia-Yun Ma ◽  
Cheng-Ling Liu ◽  
Yu-Hsien Lin ◽  
Miao-Lin Hu ◽  
...  
Keyword(s):  
Drug Effects ◽  
Pregnane X Receptor ◽  
Therapeutic Index ◽  
Receptor Activation ◽  
Dependent Manner ◽  
Metabolizing Enzymes ◽  
Sesame Seeds ◽  
Common Causes ◽  
Underlying Mechanisms ◽  
Dose Dependent

Inconsistent expression and regulation of drug-metabolizing enzymes (DMEs) are common causes of adverse drug effects in some drugs with a narrow therapeutic index (TI). An important cytochrome, cytochrome P450 3A4 (CYP3A4), is predominantly regulated by a nuclear receptor, pregnane X receptor (PXR). Sesamin, a major lignan constituent in sesame seeds and oil, exhibits a variety of biological functions; however, the effect of sesamin on the modulation of CYP3A4 is not well understood. In this study, the effects of sesamin on the PXR-CYP3A4 pathway were characterized, as well as the underlying mechanisms of those effects. Sesamin potently attenuated CYP3A4 induction in a dose-dependent manner by blocking the activation of PXR. The PXR inducer-mediated inhibition of CYP3A4 was further evidenced by the ability of sesamin to attenuate the effects of several PXR ligands in the CYP3A4 reporter assay. Further mechanistic studies showed that sesamin inhibited PXR by interrupting the interacting with coregulators. These results may lead to the development of new therapeutic and dietary approaches to reduce the frequency of inducer-drug interaction. Sesamin was established as a novel inhibitor of PXR and may be useful for modulating DMEs expression and drug efficacies. Modification of CYP3A4 expression and activity by consumption of sesamin may have important implications for drug safety.

scholarly journals The impact of supplementary short rest breaks on task performance – A meta-analysis

2016 ◽  
Vol 2016 (2) ◽  
Author(s):  
Johannes Wendsche ◽  
Andrea Lohmann-Haislah ◽  
Jürgen Jürgen
Keyword(s):  
Task Performance ◽  
Meta Analysis ◽  
Well Being ◽  
Working Time ◽  
Future Research ◽  
Performance Improvements ◽  
Positive Effects ◽  
Underlying Mechanisms ◽  
Rest Breaks ◽  
The Impact

Within-shift rest breaks are important to prevent an accumulation of impairing short-term effects of strain over working time. In this meta-analysis (k = 11, N = 705), we investigated how supplementary, frequent short rest breaks affect task performance and strain. We found positive effects on quality (g = 0.23) and quantity (g = 0.12) measures of task performance. The mean reduction of working time due to rest breaks was 9.3%. Performance improvements occurred not at costs of higher strain. Thus, our study shows that both employees’ performance and well-being benefits from scheduled within-shift breaks. We found no further effects of potentially moderating variables. Future research should examine the boundary conditions and underlying mechanisms of these effects.

scholarly journals Periodic fluctuations in recruitment success of Atlantic cod

2020 ◽  
Vol 77 (2) ◽  
pp. 236-246
Author(s):  
Anna Rindorf ◽  
Noel Cadigan ◽  
Daniel Howell ◽  
Margit Eero ◽  
Henrik Gislason
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Recruitment Success ◽  
The North ◽  
Reading Errors ◽  
Adult Growth ◽  
Predation Mortality ◽  
Common Causes ◽  
Periodic Fluctuations ◽  
Underlying Mechanisms

Autocorrelation in recruitment success of fish is frequently reported, but the underlying mechanisms are generally only vaguely alluded to. We analysed recruitment success of 21 cod (Gadus morhua) stocks in the North Atlantic to investigate possible common causes of autocorrelation in recruitment. We found autocorrelation and periodic fluctuations in recruitment success and adult growth in just above half of the stocks considered and investigated six possible underlying mechanisms. With three exceptions, the variations in recruitment success were not significantly related to temperature or growth anomalies, indicating that the variation was not caused by temperature-dependent survival or growth-dependent spawning products. Further, a link between recruitment and subsequent spawning biomass could not explain the observed recruitment patterns. Slow-growing cod stocks tended to exhibit longer cycles and positive autocorrelations consistent with dilution of predation mortality by adjacent large year classes or age reading errors, whereas fast-growing cod stocks showed shorter cycles and no significant autocorrelation at lag 1. Both types exhibited significant negative autocorrelations consistent with cannibalism at one or more lags greater than lag 1.

Health and well-being of lesbians, gay men and bisexual people in later life: examining the commonalities and differences from quantitative research

2019 ◽  
pp. 191-208 ◽  
Author(s):  
Mark Hughes
Keyword(s):  
Quantitative Research ◽  
Later Life ◽  
Well Being ◽  
International Studies ◽  
Health And Wellbeing ◽  
Quantitative Studies ◽  
Or Practice ◽  
And Bisexual ◽  
Lgbt People ◽  
Bisexual People

Findings from quantitative research speak to majority experiences and general patterns within populations. However, the aggregation of people into one LGBT category risks quantitative research – and the translation of its results into policy or practice – misrepresenting the issues and needs across the diversity of LGBT people. This chapter argues that what is needed is careful unpacking of quantitative findings to ensure that this diversity is respected. To facilitate this, the chapter examines some of the commonalities and differences in quantitative findings on lesbian, gay and bisexual older people’s health and wellbeing. By parsing the findings from international studies, the chapter identifies trends in relation to physical wellbeing, disability, alcohol consumption, smoking, and mental health. Despite their limitations, it is argued that these quantitative studies provide insights into the structural intersectionality, alongside political and representational intersectionality, that operates to marginalise lesbian, gay and bisexual people in later life..

scholarly journals Cold weather increases the risk of scrotal torsion events: results of an ecological study of acute scrotal pain in Scotland over 25 years

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chidi N. Molokwu ◽  
Judith K. Ndoumbe ◽  
Chris M. Goodman
Keyword(s):  
Ambient Temperature ◽  
Ecological Study ◽  
Inverse Correlation ◽  
Cold Weather ◽  
Scrotal Pain ◽  
Acute Scrotal Pain ◽  
Common Causes ◽  
Group A ◽  
Underlying Mechanisms ◽  
Group B

Abstract The role of ambient temperature in the aetiology of acute scrotal pain (ASP) remains uncertain. The most common causes of ASP are torsion of the testis (TT) or its appendages (TA) and epidymo-orchitis (EO). We undertook an ecological study of ASP in Scotland to determine whether a seasonal variation could be observed. Episode reports for TT, TA and EO in Scotland over 25 years were collated monthly. Statistical analyses were performed to determine whether changes in ambient temperature during the year could explain variations in monthly frequency. 7882 episodes of TT and TA (Group A), and 25,973 episodes of EO (Group B) were reported. There was significant variance in the frequency of Group A (p < 0.0001) and B (p = 0.0031) episodes by month, higher frequency of Group A episodes in the colder half of the year (p < 0.0001), and an inverse correlation between the frequency of Group A episodes and ambient temperature (Spearman r = − 0.8757, 95% CI − 0.9661 to − 0.5941, p = 0.0004). Ambient temperature is likely to be playing a role in the aetiology of TT and TA in Scotland but not EO. Further study is warranted to explain underlying mechanisms.

The limits of human performance

2008 ◽  
Vol 44 ◽  
pp. 11-26 ◽  
Author(s):  
Ralph Beneke ◽  
Dieter Böning
Keyword(s):  
Human Performance ◽  
Safety Margin ◽  
Afferent Input ◽  
Metabolic Energy ◽  
Human Organism ◽  
Mechanical Resistance ◽  
As Doping ◽  
Gene And Protein Expression ◽  
Underlying Mechanisms ◽  
Biochemical Research

Human performance, defined by mechanical resistance and distance per time, includes human, task and environmental factors, all interrelated. It requires metabolic energy provided by anaerobic and aerobic metabolic energy sources. These sources have specific limitations in the capacity and rate to provide re-phosphorylation energy, which determines individual ratios of aerobic and anaerobic metabolic power and their sustainability. In healthy athletes, limits to provide and utilize metabolic energy are multifactorial, carefully matched and include a safety margin imposed in order to protect the integrity of the human organism under maximal effort. Perception of afferent input associated with effort leads to conscious or unconscious decisions to modulate or terminate performance; however, the underlying mechanisms of cerebral control are not fully understood. The idea to move borders of performance with the help of biochemicals is two millennia old. Biochemical findings resulted in highly effective substances widely used to increase performance in daily life, during preparation for sport events and during competition, but many of them must be considered as doping and therefore illegal. Supplements and food have ergogenic potential; however, numerous concepts are controversially discussed with respect to legality and particularly evidence in terms of usefulness and risks. The effect of evidence-based nutritional strategies on adaptations in terms of gene and protein expression that occur in skeletal muscle during and after exercise training sessions is widely unknown. Biochemical research is essential for better understanding of the basic mechanisms causing fatigue and the regulation of the dynamic adaptation to physical and mental training.

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