Intraocular pressure and choroidal thickness respond differently to lower body negative pressure during spaceflight

Spaceflight associated neuro-ocular syndrome (SANS) develops during long-duration (>1 month) spaceflight presumably because of chronic exposure to a headward fluid shift that occurs in weightlessness. We aimed to determine whether reversing this headward fluid shift with acute application of lower body negative pressure (LBNP) can influence outcome measures at the eye. Intraocular pressure (IOP) and subfoveal choroidal thickness were therefore evaluated by tonometry and optical coherence tomography (OCT), respectively, in 14 International Space Station crewmembers before flight in the seated, supine, and 15° head-down tilt (HDT) postures and during spaceflight, without and with application of 25 mmHg LBNP. IOP in the preflight seated posture was 14.4 mmHg (95% CI, 13.5-15.2 mmHg) and spaceflight elevated this value by 1.3 mmHg (95% CI, 0.7-1.8 mmHg, P<0.001). Acute exposure to LBNP during spaceflight reduced IOP to 14.2 mmHg (95% CI, 13.4-15.0 mmHg), which was equivalent to that of the seated posture (P>0.99), indicating that venous fluid redistribution by LBNP can influence ocular outcome variables during spaceflight. Choroidal thickness during spaceflight (374 µm, 95% CI, 325-423 µm) increased by 35 µm (95% CI, 25-45 µm, P<0.001), compared to the preflight seated posture (339 µm, 95% CI, 289-388 µm). Acute use of LBNP during spaceflight did not affect choroidal thickness (381 µm, 95% CI, 331-430 µm, P=0.99). The finding that transmission of reduced venous pressure by LBNP did not decrease choroidal thickness suggests that engorgement of this tissue during spaceflight may reflect changes that are secondary to the chronic cerebral venous congestion associated with spaceflight.

Where Narrative and Performance Meet

This chapter contextualizes and provides a translation of the Rāmāyaṇa Saṃkṣēpam, a concise summary of the Ramayana story, which serves as a training manual for a Kutiyattam artist preparing for the stage. It is taught by the guru to the disciple during the earliest stage of Kutiyattam training. Each of the five active schools of Kutiyattam in Kerala uses its own abridged version of the story to initiate pupils into an extended multiphase training of the performance form through gesture and facial expression. Performed in a seated posture, the Rāmāyaṇa Saṃkṣēpam demonstrates episodes in the Ramayana story with a focus on specific characters and a gamut of emotions which provide the basic vocabulary of Kutiyattam performance. The summary that is translated here is sourced from a handwritten text in Malayalam belonging to the Nepathya School in Moozhikkulam, Kerala.

Knee Extensor Strength Measurement in Patients With Limited Physical Activity Using a Supine Dynamometer Anchoring Frame

Objective To investigate the reliability of knee extensor strength measurements using a supine hand-held dynamometer (HHD) anchoring frame in patients with limited physical activity. Although an HHD is suitable for bedside use, its inter-rater reliability is low because measurements can be influenced by tester strength.Methods Maximal knee extensor isometric strength was measured using an HHD anchored to the supine frame. Three trials of three maximal contractions were assessed by two raters.Results A total of 33 inpatients who were non-ambulatory due to acute illness participated in the study. The intraclass correlation coefficients were 0.974 (inter-rater) and 0.959 (intra-rater). The minimal detectable changes in intra- and inter-observer measurements were 29.46 N (24.10%) and 36.73 N (29.26%), respectively. The limits of agreement ranged from -19.79% to 24.81% for intra-rater agreement and from -21.45% to 37.07% for inter-rater agreement.Conclusion The portable dynamometer anchoring system can measure the isometric strength of the knee extensor reliably in the supine position, and could be used for measurements in patients who have difficulty visiting the laboratory and maintaining a seated posture.

Impact of the 2020 COVID-19 Pandemic on Older Adults’ Perceived Sedentary Behavior and Physical Activity

Starting in March 2019, stay-at-home orders meant to control the spread of the COVID-19 pandemic have limited movement, activities, and services in Washington State. For older adults, who are the most sedentary age group, we hypothesized that these public health measures encouraged increased sedentary behavior (SB) and reduced physical activity (PA) levels. To explore this, we conducted 25 semi-structured interviews with a sub-sample of participants in an ongoing sedentary behavior reduction intervention. Interviews were recorded and transcribed, and an iterative coding process was used to extract key themes related SB changes, PA changes, and other impacts of COVID-19 social distancing measures. Most participants reported an increase in SB due to limitations on leaving their home, canceled activities, increased free time in which to pursue indoor hobbies traditionally done in a seated posture (reading, sewing, tv, etc.), and feelings of depression or lack of motivation. Some participants suggested that these restrictions also led to a decrease in their PA and exercise levels due to cancelled fitness classes, loss of social support around exercise routines, and fear of leaving the house. However, other participants reported that the social distancing measures have allowed them to increase their PA levels, giving them more time to walk outdoors or pursue active outdoor hobbies like tennis, gardening, or home improvement tasks. In conclusion, the COVID-19 pandemic and associated social distancing measures have had varying impacts on participant perceived SB and PA levels. It is unclear how these changes will be maintained when pandemic restrictions are lifted.

Regulating distance to the screen while engaging in difficult tasks

Regulation of distance to the screen (i.e., head-to-screen distance, fluctuation of head-to-screen distance) has been proved to reflect the cognitive engagement of the reader. However, it is still not clear (a) whether regulation of distance to the screen can be a potential parameter to infer high cognitive load and (b) whether it can predict the upcoming answer accuracy. Configuring tablets or other learning devices in a way that distance to the screen can be analyzed by the learning software is in close reach. The software might use the measure as a person-specific indicator of need for extra scaffolding. In order to better gauge this potential, we analyzed eye-tracking data of children (N = 144, Mage = 13 years, SD = 3.2 years) engaging in multimedia learning, as distance to the screen is estimated as a by-product of eye tracking. Children were told to maintain a still seated posture while reading and answering questions at three difficulty levels (i.e., easy vs. medium vs. difficult). Results yielded that task difficulty influences how well the distance to the screen can be regulated, supporting that regulation of distance to the screen is a promising measure. Closer head-to-screen distance and larger fluctuation of head-to-screen distance can reflect that participants are engaging in a challenging task. Only large fluctuation of head-to-screen distance can predict the future incorrect answers. The link between distance to the screen and processing of cognitive task can obtrusively embody reader’s cognitive states during system usage, which can support adaptive learning and testing.

Can Physical Activity While Sedentary Produce Health Benefits? A Single-Arm Randomized Trial

Background Sedentary time poses a risk to health. Substituting physical activity for inactivity is obvious but this requires a behavior change. Interventions advocated to decrease uninterrupted physical inactivity (defined as Metabolic Equivalent of Task (METS) less than 1.5) are important. One such intervention is accomplished with the Gentle Jogger (GJ), a low risk motorized wellness device which produces effortless, rapid motion of the lower extremities simulating locomotion or fidgeting. GJ produces health benefits in type 2 diabetes, heart disease, and high blood pressure. The purpose of this trial was to ascertain whether GJ increases METS above 1.5 to explain its effectiveness despite sedentary behavior or whether tapping is responsible. Methods A randomized single-arm trial was conducted. Subjects were randomized to begin the study in either the supine or seated postures and on the same day crossed over with the starting posture reversed. Oxygen consumption was measured at rest and during GJ. Results Twenty-six subjects were studied (15 women and 11 men) with a mean age of 44 ± 15 years and BMI 27.9 ± 5.0, 19 were overweight or obese, and 7 had normal BMI. GJ increased oxygen consumption and METS 15% in the seated posture and 13% in the supine posture. No individual receiving GJ achieved METS exceeding 1.5. Conclusions In a moderately obese population, GJ in seated or supine posture did not exceed 1.5 METS. The values are comparable to those reported for sit-stand interventions and cannot explain the health benefits of GJ. Trial registration ClinicalTrials.gov, NCT03602365. Registered on July 26, 2018

Rock and roll: The influence of bicycle lean on the mechanics of non-seated cycling

When riding off the saddle during climbing and sprinting, cyclists appear to coordinate the rhythmic, vertical oscillations of their centre of mass (CoM) with the side-to-side lean of the bicycle. Is the coordination of these two motions merely a stability requirement, or could it also be a strategy to more effectively generate crank power? Here we combined a kinematic and kinetic approach to understand how different constraints on bicycle lean influence CoM movement and limb mechanics during non-seated cycling. Ten participants cycled in a non-seated posture at a power output of $5\ W\cdot kg^{-1}$ and a cadence of 70 rpm under three bicycle lean conditions: unconstrained on rollers (Unconstrained), under instruction to self-restrict bicycle lean on rollers (Self-Restricted) and constrained in a bicycle trainer (Trainer). Bicycle lean angle in the Unconstrained condition was greater than Self-Restricted and in the Trainer. Vertical CoM displacement, peak vertical crank force, and peak instantaneous crank power in the Unconstrained condition were greater than Self-Restricted but similar to in the Trainer. The amount and rate of energy lost and gained by the rider's CoM in the Unconstrained condition was greater than Self-restricted but similar to in the Trainer. The differences in joint power contributions to total joint power (hip, knee, ankle, and upper body) between conditions were inconclusive. We interpret these results as evidence bicycle lean plays an important role in facilitating the production of high crank force and power output during non-seated cycling by allowing a greater non-muscular contribution to crank power.