The association of handgrip strength and mortality: What does it tell us and what can we do with it?

© Copyright 2019, Mary Ann Liebert, Inc., publishers 2019. The relationship between grip strength and mortality is often used to underscore the importance of resistance exercise in physical activity guidelines. However, grip strength does not appear to appreciably change following traditional resistance training. Thus, grip strength could be considered reflective of strength independent of resistance exercise. If true, grip strength is not necessarily informing us of the importance of resistance exercise as an adult, but potentially highlighting inherent differences between individuals who are stronger at baseline compared to their weaker counterpart. The purpose of this article is to discuss: (1) potential factors that may influence grip strength and (2) hypothesize strategies that may be able to influence grip strength and ultimately attain a higher baseline level of strength. Although there appears to be a limited ability to augment grip strength as an adult, there may be critical periods during growth/development during which individuals can establish a higher baseline. Establishing a high baseline of strength earlier in life may have long-term implications related to mortality and disease

Further explorations of illness uncertainty: Carer’s experiences of Parkinson’s disease

Objective: Dominant models of illness uncertainty define uncertainty as ‘an inability to determine the meaning of illness-related events’. Recent research has shown patient uncertainty to be multidimensional encompassing personal issues indirectly affected by illness. The nature of carer uncertainty has yet to be fully explored. The present study aimed to investigate the nature of illness uncertainty in the carers of patients with Parkinson’s disease (PD). Design: Eighteen carers of a spouse with PD participated in semi-structured interviews. Transcripts were thematically analysed, statements were coded as uncertain if they reflected ‘a lack of certainty, or a state of limited knowledge, understanding or worry regarding an existing or future outcome’. Results: The domains of uncertainty expressed by carers closely fitted the five domain framework of patient uncertainty: symptoms and prognosis, medical management, self-management, social functioning and impact. An additional ‘carer-role’ domain was identified. Conclusions: Carer uncertainty about PD went beyond issues directly related to the illness. The findings have implications for research into uncertainty suggesting that widely used measures may not be accurately capturing the nature of carer uncertainty about chronic illness. The breadth of uncertainty reported has implications for the provision of appropriate support to improve caregiver well-being

Differential electrophysiological response during rest, self-referential, and non-self-referential tasks in human posteromedial cortex

The electrophysiological basis for higher brain activity during rest and internally directed cognition within the human default mode network (DMN) remains largely unknown. Here we use intracranial recordings in the human posteromedial cortex (PMC), a core node within the DMN, during conditions of cued rest, autobiographical judgments, and arithmetic processing. We found a heterogeneous profile of PMC responses in functional, spatial, and temporal domains. Although the majority of PMC sites showed increased broad gamma band activity (30-180 Hz) during rest, some PMC sites, proximal to the retrosplenial cortex, responded selectively to autobiographical stimuli. However, no site responded to both conditions, even though they were located within the boundaries of the DMN identified with resting-state functional imaging and similarly deactivated during arithmetic processing. These findings, which provide electrophysiological evidence for heterogeneity within the core of the DMN, will have important implications for neuroimaging studies of the DMN

Limb Occlusion Pressure: A Method to Assess Changes in Systolic Blood Pressure

Although often used as a surrogate, comparisons between traditional blood pressure measurements and limb occlusion assessed via hand-held Doppler have yet to be completed. Using limb occlusion pressure as a method of assessing systolic pressure is of interest to those studying the acute effects of blood flow restriction, where the removal of the cuff may alter the physiological response. Purpose: We sought to determine how changes in limb occlusion pressure track with changes in traditional assessments of blood pressure. Basic Procedures: Limb occlusion pressure measured by hand-held Doppler and blood pressure measured by an automatic blood pressure cuff were assessed at rest and following isometric knee extension (post and 5 minutes post). Main Findings: Each individual had a similar dispersion from the mean value for both the limb occlusion pressure measurement and traditional systolic blood pressure measurement [BF10: 0.33; median (95% credible interval): 0.02 (−6.0, 5.9) %]. In response to lower body isometric exercise, blood pressure changed across time. The difference between measurements was small at immediately post and 5 minutes post. The Bayes factors were in the direction of the null but did not exceed the threshold needed to accept the null hypothesis. However, at 5 minutes post, the differences were within the range of practical equivalence (within ± 4.6%). Principal Conclusions: Our findings suggest that changes in limb occlusion pressure measured by hand-held Doppler track similarly to traditional measurements of brachial systolic blood pressure following isometric knee extension exercise

The Basics of Training for Muscle Size and Strength: A Brief Review on the Theory

The periodization of resistance exercise is often touted as the most effective strategy for optimizing muscle size and strength adaptations. This narrative persists despite a lack of experimental evidence to demonstrate its superiority. In addition, the general adaptation syndrome, which provides the theoretical framework underlying periodization, does not appear to provide a strong physiological rationale that periodization is necessary. Hans Selye conducted a series of rodent studies which used toxic stressors to facilitate the development of the general adaptation syndrome. To our knowledge, normal exercise in humans has never been shown to produce a general adaptation syndrome. We question whether there is any physiological rationale that a periodized training approach would facilitate greater adaptations compared with nonperiodized approaches employing progressive overload. The purpose of this article is to briefly review currently debated topics within strength and conditioning and provide some practical insight regarding the implications these reevaluations of the literature may have for resistance exercise and periodization. In addition, we provide some suggestions for the continued advancement within the field of strength and conditioning

Opposing brain differences in 16p11.2 deletion and duplication carriers

Deletions and duplications of the recurrent ∼600 kb chromosomal BP4–BP5 region of 16p11.2 are associated with a broad variety of neurodevelopmental outcomes including autism spectrum disorder. A clue to the pathogenesis of the copy number variant (CNV)'s effect on the brain is that the deletion is associated with a head size increase, whereas the duplication is associated with a decrease. Here we analyzed brain structure in a clinically ascertained group of human deletion (N = 25) and duplication (N = 17) carriers from the Simons Variation in Individuals Project compared with age-matched controls (N = 29 and 33, respectively). Multiple brain measures showed increased size in deletion carriers and reduced size in duplication carriers. The effects spanned global measures of intracranial volume, brain size, compartmental measures of gray matter and white matter, subcortical structures, and the cerebellum. Quantitatively, the largest effect was on the thalamus, but the collective results suggest a pervasive rather than a selective effect on the brain. Detailed analysis of cortical gray matter revealed that cortical surface area displays a strong dose-dependent effect of CNV (deletion > control > duplication), whereas average cortical thickness is less affected. These results suggest that the CNV may exert its opposing influences through mechanisms that influence early stages of embryonic brain development

The Politics of Commerce : The Congress of Chambers of Commerce of the Empire, 1886-1914

Peer reviewedPublisher PD

Evolved Eclipsing Binaries and the Age of the Open Cluster NGC 752

We present analyses of improved photometric and spectroscopic observations for two detached eclipsing binaries at the turnoff of the open cluster NGC 752: the 1.01 day binary DS And and the 15.53 d BD $+$37 410. For DS And, we find $M_1 = 1.692\pm0.004\pm0.010 M_\odot$, $R_1 = 2.185\pm0.004\pm0.008 R_\odot$, $M_2 = 1.184\pm0.001\pm0.003 M_\odot$, and $R_2 = 1.200\pm0.003\pm0.005 R_\odot$. We either confirm or newly identify unusual characteristics of both stars in the binary: the primary star is found to be slightly hotter than the main sequence turn off and there is a more substantial discrepancy in its luminosity compared to models (model luminosities are too large by about 40%), while the secondary star is oversized and cooler compared to other main sequence stars in the same cluster. The evidence points to non-standard evolution for both stars, but most plausible paths cannot explain the low luminosity of the primary star. BD $+$37 410 only has one eclipse per cycle, but extensive spectroscopic observations and the TESS light curve constrain the stellar masses well: $M_1 = 1.717\pm0.011 M_\odot$ and $M_2 = 1.175\pm0.005 M_\odot$. The radius of the main sequence primary star near $2.9R_\odot$ definitively requires large convective core overshooting ($> 0.2$ pressure scale heights) in models for its mass, and multiple lines of evidence point toward an age of $1.61\pm0.03\pm0.05$ Gyr (statistical and systematic uncertainties). Because NGC 752 is currently undergoing the transition from non-degenerate to degenerate He ignition of its red clump stars, BD $+$37 410 A directly constrains the star mass where this transition occurs.Comment: 34 pages, 23 figures, accepted for Astronomical Journa

Evolved Eclipsing Binaries and the Age of the Open Cluster NGC 752

We present analyses of improved photometric and spectroscopic observations for two detached eclipsing binaries at the turnoff of the open cluster NGC 752: the 1.01 days binary DS And and the 15.53 days BD +37 410. For DS And, we find M1 = 1.692 ± 0.004 ± 0.010M⊙, R1 = 2.185 ± 0.004 ± 0.008R⊙, M2 = 1.184 ± 0.001 ± 0.003M⊙, and R2 = 1.200 ± 0.003 ± 0.005R⊙. We either confirm or newly identify unusual characteristics of both stars in the binary: the primary star is found to be slightly hotter than the main-sequence turnoff and there is a more substantial discrepancy in its luminosity compared to models (model luminosities are too large by about 40%), while the secondary star is oversized and cooler compared to other main-sequence stars in the same cluster. The evidence points to nonstandard evolution for both stars, but most plausible paths cannot explain the low luminosity of the primary star. BD +37 410 only has one eclipse per cycle, but extensive spectroscopic observations and the Transiting Exoplanet Survey Satellite light curve constrain the stellar masses well: M1 = 1.717 ± 0.011M⊙ and M2 = 1.175 ± 0.005M⊙. The radius of the main-sequence primary star near 2.9R⊙ definitively requires large convective core overshooting (>0.2 pressure scale heights) in models for its mass, and multiple lines of evidence point toward an age of 1.61 ± 0.03 ± 0.05 Gyr (statistical and systematic uncertainties). Because NGC 752 is currently undergoing the transition from nondegenerate to degenerate He ignition of its red clump stars, BD +37 410 A directly constrains the star mass where this transition occurs