Combined protein and calcium β-hydroxy-β-methylbutyrate induced gains in leg fat free mass: a double-blinded, placebo-controlled study

Background The leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) is widely used as an ergogenic supplement to increase resistance-training induced gains in fat free mass (FFM) and strength in healthy adults. Recent studies have questioned the effectiveness of HMB, particularly when a high protein diet is habitually consumed. To investigate the additive resistance-training induced effects of HMB and protein in untrained individuals, we conducted a randomized double-blind, placebo-controlled study that compared the effects of combined protein and HMB supplementation to protein supplementation alone on FFM and muscle strength after 12-week resistance training. Methods Sixteen healthy men (22 +/- 2 yrs) performed a periodized resistance-training program for twelve weeks (four sessions per week). The program comprised two mesocycles, characterized by a linear periodization and non-linear periodization, respectively, and separated by a 1-week tapering period. All participants received 60 g of whey protein on training days and 30 g of whey protein (WP) on non-training days. Participants were randomly assigned to additionally receive 3 g of calcium HMB (WP + HMB) or a placebo (WP + PLA). Body composition and physical fitness were tested before and after the 12-week training program. Whole-body and arm and leg fat free mass (FFM) were assessed by bioimpedance spectroscopy; upper arm and leg fat free cross sectional areas were also quantified using magnetic resonance imaging (MRI); upper and lower body strength were measured by One-repetition maximum (1-RM) bench press and leg press. Results Whole-body and segmental FFM increased in both groups (P < 0.001). However, gains in leg FFM were higher in WP + HMB vs. WP + PLA (arm FFM: + 6.1% vs. + 9.2%, P = 0.2; leg FFM: + 14.2% vs. + 7.0%, P < 0.01). No change in fat mass was observed (P = 0.59). 1-RM increased in both groups (P < 0.001). Conclusions Combined protein and HMB supplementation resulted in segmental, but not whole-body increases in FFM compared to protein supplementation alone. These findings could explain some of the controversial effects of HMB reported in previous studies and have practical implications for maximizing training-induced gains in FFM and clinical conditions associated with skeletal muscle deconditioning such as aging, sedentary lifestyles, bed rest and spaceflight

Helioseismology of Sunspots: A Case Study of NOAA Region 9787

Various methods of helioseismology are used to study the subsurface properties of the sunspot in NOAA Active Region 9787. This sunspot was chosen because it is axisymmetric, shows little evolution during 20-28 January 2002, and was observed continuously by the MDI/SOHO instrument. (...) Wave travel times and mode frequencies are affected by the sunspot. In most cases, wave packets that propagate through the sunspot have reduced travel times. At short travel distances, however, the sign of the travel-time shifts appears to depend sensitively on how the data are processed and, in particular, on filtering in frequency-wavenumber space. We carry out two linear inversions for wave speed: one using travel-times and phase-speed filters and the other one using mode frequencies from ring analysis. These two inversions give subsurface wave-speed profiles with opposite signs and different amplitudes. (...) From this study of AR9787, we conclude that we are currently unable to provide a unified description of the subsurface structure and dynamics of the sunspot.Comment: 28 pages, 18 figure

Dynamic ensemble prediction of cognitive performance in spaceflight

During spaceflight, astronauts face a unique set of stressors, including microgravity, isolation, and confinement, as well as environmental and operational hazards. These factors can negatively impact sleep, alertness, and neurobehavioral performance, all of which are critical to mission success. In this paper, we predict neurobehavioral performance over the course of a 6-month mission aboard the International Space Station (ISS), using ISS environmental data as well as self-reported and cognitive data collected longitudinally from 24 astronauts. Neurobehavioral performance was repeatedly assessed via a 3-min Psychomotor Vigilance Test (PVT-B) that is highly sensitive to the effects of sleep deprivation. To relate PVT-B performance to time-varying and discordantly-measured environmental, operational, and psychological covariates, we propose an ensemble prediction model comprising of linear mixed effects, random forest, and functional concurrent models. An extensive cross-validation procedure reveals that this ensemble outperforms any one of its components alone. We also identify the most important predictors of PVT-B performance, which include an individual's previous PVT-B performance, reported fatigue and stress, and temperature and radiation dose. This method is broadly applicable to settings where the main goal is accurate, individualized prediction of human behavior involving a mixture of person-level traits and irregularly measured time series

Comparison of double sensor, skin, and rectal temperature recording for determining circadian rhthm

Background: In chronobiology studies, the circadian rhythm of core body temperature has often been monitored via rectal temperature recordings. Compliance with rectal recordings, however, limits voluntary participation and prevents a broader spectrum of investigations. With the progress of technology, systems have been developed which allow a measurement of the core body temperature from an intact skin surface, such as the Double Sensor [1], a skin surface temperature and heat-flux combining device. Studies regarding how well such systems reflect the circadian rhythm of core body temperature, however, are lacking. Material & Methods: As part of the 2nd Berlin BedRest Study (BBR2-2), subjects underwent micro-g simulated conditions, i.e. 6\ub0 head-down tilt bed-rest. On bed-rest day 49, 24 hours temperature profiles were obtained in seven health men by a single skin surface temperature sensor and the Double Sensor, each placed at forehead (Tfhd, DSfhd) and sternum (Tste, DSste), and by a rectal probe (Trec). The degree of parallelism between measured temperature variables was assessed by calculating the Pearson correlation coefficient r. Rhythm characteristics determined by fitting a single cosine curve included MESOR, amplitude, and acrophase, and were statistically tested for significance by Student's paired t- test. Results: Averaged value (\ub1 SD) of Pearson\u2019s r was .867 (.059), .797 (.097), .519 (.373), -.021 (.549) for correlation between Trec with DSfhd, Tfhd, DSste, and Tste, respectively. The correlation mean demonstrated a good parallelism between Trec and temperatures obtained from the forehead. Regarding the rhythm parameters MESOR, amplitude, and acrophase, no significant difference was found between Trec and DSfhd, but between Tfhd and DSfhd as well as between Tfhd and Trec. Discussion & Conclusions: Not the skin surface temperature recordings, but the temperatures of the Double Sensor from the forehead seem promising for determining the circadian rhythm of core body temperature in occupational and environmental medicine on earth and space, where the use of rectal probes is not feasible or desired. References: 1. Gunga HC, Sandsund M, Reinertsen RE, Sattler F and Koch J. A non-invasive device to continuously determine heat strain in humans. Journal of Thermal Biology 33: 297-307, 2008

Continuous and Intermittent Artificial Gravity as a Countermeasure to the Cognitive Effects of 60 Days of Head-Down Tilt Bed Rest

Environmental and psychological stressors can adversely affect astronaut cognitive performance in space. This study used a 6° head-down tilt bed rest (HDBR) paradigm to simulate some of the physiologic changes induced by microgravity. Twenty-four participants (mean ± SD age 33.3 ± 9.2 years, N = 16 men) spent 60 consecutive days in strict HDBR. They were studied in three groups of eight subjects each. One group served as Control, whereas the other two groups received either a continuous or intermittent artificial gravity (AG) countermeasure of 30 min centrifugation daily (1 g acceleration at the center of mass and 2 g at the feet). Participants performed all 10 tests of NASA’s Cognition battery and a brief alertness and mood survey repeatedly before, during, and after the HDBR period. Test scores were adjusted for practice and stimulus set difficulty effects. A modest but statistically significant slowing across a range of cognitive domains was found in all three groups during HDBR compared to baseline, most consistently for sensorimotor speed, whereas accuracy was unaffected. These changes were observed early during HDBR and did not further worsen or improve with increasing time in HDBR, except for emotion recognition performance. With increasing time spent in HDBR, participants required longer time to decide which facial emotion was expressed. They were also more likely to select categories with negative valence over categories with neutral or positive valence. Except for workload, which was rated lower in the Control group, continuous or intermittent AG did not modify the effect of HDBR on cognitive performance or subjective responses. Participants expressed several negative survey responses during HDBR relative to baseline, and some of the responses further deteriorated during recovery, which highlights the importance of adequate medical and psychological support during extended duration HDBR studies. In conclusion, 60 days of HDBR were associated with moderate cognitive slowing and changes in emotion recognition performance, but these effects were not mitigated by either continuous or intermittent exposure to AG for 30 min daily

Phase shifts of circadian core body temperature profiles during Mars500

A growing body of research indicates that a misalignment of circadian rhythms can be detrimental to mental and physical health. Long-term space missions may also potentially alter circadian rhythms, and pose a critical risk to crew health and safety. The long-term impact of isolation and confinement on circadian rhythms has not been fully characterized. We here assessed the impact of the Mars500 study on the circadian phase of core body temperature (CBT). CBT was recorded continuously for 24 h at the forehead using a recently proposed heat-flux technique (Double Sensor) [1] before (BDC) and during (ISO-20, ISO-60, ISO-140, ISO-200, ISO-260, ISO-320, ISO-400, ISO-460) the mission. Each recording was then subjected to cosinor analysis to determine acrophase for each subject and session. A linear mixed model treating \u201cTime\u201d as fixed e\u21b5ect was fit to phase, including random e\u21b5ects (intercepts and slopes) to account for individual subject variation. To analyze whether the rate of change in CBT was characterized by nonlinear changes over time, quadratic and cubic models were also considered. In spite of substantial inter-individual variation, visual inspection of the data indicated a phase advance during the first half of the mission (+1.4 h), after which phase returned to baseline again (phase delay of about -1.2 h relative to first mission half). At ISO-460 phase sharply advanced again to similar levels observed during the first half of the mission. This pattern was confirmed by significant linear, quadratic and cubic components of the mixed model (P<0.05). This third degree polynomial trend is well in line with recent data, showing substantial di\u21b5erences for sleep-wake cycles between the first and last the part of the 520-d mission [2]. We suggest that this specific pattern is related to a highly controlled diet, which was administered during the first half of the mission. This diet required very strict meal times, which are well known to be strong nonphotic cues for circadian entrainment [3]. In contrast, we speculate that the sudden phase advance after 400 mission days could be related to the exposure of blue light, which was exclusively employed during days 439-499 only. In conclusion, the present results indicate that long-term isolation can induce significant changes in the circadian timing system, which might be attributed to specific nonphotic and photic cues of the Mars500 experiment. [1] Respir Physiol Neurobiol, 169 (2009) S63-S68 [2] PNAS, 110 (2013) 2635-2640 [3] Science, 320 (2008) 1074\u2013107

Continuous and intermittent artificial gravity as a countermeasure to the cognitive effects of 60 days of head-down tilt bed rest

Environmental and psychological stressors can adversely affect astronaut cognitive performance in space. This study used a 6⁰ head-down tilt bed rest (HDBR) paradigm to simulate some of the physiologic changes induced by microgravity. Twenty-four participants (mean ± SD age 33.3 ± 9.2 years, N = 16 men) spent 60 consecutive days in strict HDBR. They were studied in three groups of eight subjects each. One group served as Control whereas the other two groups received either a continuous (cAG) or intermittent (iAG) artificial gravity (AG) countermeasure of 30 minute centrifugation daily (1 g acceleration at the center of mass and 2 g at the feet). The centrifugation protocol included: acceleration at 5°/s2 for 32–33 seconds until target rotation speed was achieved followed by rotation at constant velocity for either 30 minutes (cAG) or 5 minutes, with a 3minute rest, repeated six times (iAG). Deceleration was at 5°/s2 . Participants performed all 10 tests of NASA’s Cognition battery and a brief alertness and mood survey repeatedly before, during, and after the bed rest period. A modest but statistically significant slowing across a range of cognitive domains was found in all three groups during HDBR compared to baseline, most consistently for sensorimotor speed, whereas accuracy was unaffected. These changes were observed early during HDBR and did not further deteriorate or improve with increasing time in HDBR, except for emotion recognition performance. With increasing time spent in HDBR, participants required longer time to decide which facial emotion was expressed. They were also more likely to select categories with negative valence over categories with neutral or positive valence. Except for workload ratings, which were assessed lower in the Control group, continuous or intermittent AG did not modify the effect of HDBR on cognitive performance or subjective responses. Participants expressed several negative survey responses during HDBR relative to baseline, and some of the responses further deteriorated during recovery, stressing the importance of adequate medical and psychological support during extended duration HDBR studies. In conclusion, 60 days of HDBR were associated with moderate cognitive slowing and changes in emotion recognition performance, but these effects were not mitigated by either continuous or intermittent exposure to AG for 30 minutes daily

Effects of Head-Down Tilt Bed Rest Plus Elevated CO₂ on Cognitive Performance

Microgravity and elevated CO₂ levels are two important environmental spaceflight stressors that can adversely affect astronaut cognitive performance and jeopardize mission success. This study investigated the effects of 6⁰ head-down tilt bed rest (HDBR) with (N=11 participants, 30 days HDBR) and without (N=8 participants, 60 days HDBR) elevated ambient (3.73 mmHg) CO₂ concentrations on cognitive performance. Participants of both groups performed all 10 tests of NASA's Cognition battery and a brief alertness and mood survey repeatedly before, during, and after the HDBR period. Test scores were adjusted for practice and stimulus set effects. Concentrating on the first 30 days of HDBR, a modest but statistically significant slowing across a range of cognitive domains was found in both groups (Controls: -0.37 SD; 95% CI 0.48, -0.27; adjusted p<0.0001; CO₂: -0.25 SD; 95% CI 0.34, -0.16; adjusted p<0.001), most prominently for sensorimotor speed. These changes were observed early during HDBR and did not further deteriorate or improve with increasing time in HDBR. The study found similar cognitive effects of HDBR irrespective of CO₂ levels, suggesting that elevated CO₂ neither ameliorated nor worsened the HDBR effects. In both groups, cognitive performance after 15 days of recovery was statistically indistinguishable from pre-HDBR performance. However, subjects undergoing 60 days of HDBR rated themselves as feeling more sleepy, tired, physically exhausted, stressed and unhealthy during recovery compared to their 30-day counterparts

Hyper.Campus-Effects of Artificial Gravity on Structural and Functional Brain Plasticity During Head-Down Tilt Bed Rest

Artificial gravity (AG) is emerging as a candidate countermeasure against cardiovascular and musculoskeletal deconditioning associated with long duration spaceflight. Remarkably, the neural basis of cognitive performance changes (especially spatial cognition) associated with AG have received little attention. In fact, research on the effects of intermittent AG on structural and functional changes of the brain is lacking. Whereas the entire brain may be prone to structural and functional changes as a result of body unloading and AG, the hippocampal formation is a key area due to its role in spatial learning, memory, and navigation. Furthermore, the hippocampus is one of only two areas of the human brain capable of adult neurogenesis, suggesting it may be a key target for mitigating neurocognitive impairments associated with bed rest. To address this gap, we aimed to investigate effects of longduration bed rest and the efficacy of AG as a countermeasure on brain plasticity and their behavioral significance. As part of the joint NASA and ESA bed rest experiment using AG as a countermeasure (AGBRESA), we investigated the impact of 60 days of -6° head down-tilt bed rest with and without AG using two different centrifugation protocols (intermittent vs. continuous exposure) on brain structure and function, cognitive performance and key neurotrophic growth factors. A total of N=24 subjects were randomly assigned to one of the three following groups of N=8: bed rest only (CTRL), bed rest plus intermittent AG (iAG), bed rest plus continuous AG (cAG). Our primary outcomes were structural and functional changes of the brain using high-resolution imaging sequences. In addition to structural and resting state functional imaging, we also employed various fMRI tasks, specifically targeting pattern separation and affective processing. Neurobehavioral testing comprised a range of tasks, assessing visuospatial navigation, working memory and executive control. Saliva and venous blood samples were collected to better understand the mechanisms underlying any changes in brain structure and function. The study was conducted at DLR :envihab, and involved two campaigns of 12 participants each. The final sample included the target N=24 subjects with N=8 CTRL (6 men, 2 women, mean age: 35 yrs), N=8 cAG (5 men, 3 women, mean age: 32 yrs), and N=8 iAG (5 men, 3 woman, mean age: 34 yrs). The following data were collected, and analyzed: (1) 96 multimodal brain imaging sessions performed on BDC-3, HDT30, HDT59, and R+11 (100% of nominal); (2) 120 sessions of Spatial Cognition Battery 1 comprising four tasks, and administered on BDC-3, HDT2, HDT30, HDT59, and R+12 (99.4% of nominal); (3) 24 sessions of Spatial Cognition Battery 2 comprising four tasks administered on HDT59 or HDT60 (93.3% of nominal); (4) 312 sessions of NASA’s Cognition Battery comprising 10 tasks performed on BDC-9, BDC-7, BDC-6, HDT1, HDT3, HDT5, HDT14, HDT28, HDT42, HDT57, R+1, R+5, and R+12 (98.84% of nominal); (5) 432 collections of saliva cortisol collected in the morning and evening on BDC-6, BDC-3, HDT2, HDT14, HDT30, HDT42, HDT56, R+1, and R+10 (99.6% of nominal); and (6) 296 venous blood collections collected in the morning and after AG (only during HDBR) on BDC-6, BDC-3, HDT02, HDT14, HDT30, HDT42, HDT56, R+1, and R+10, providing a total of 2072 samples to determine BDNF, IGF-1, VEGF, NF-L, IL-1b, IL-6, and TNa (99% of nominal). In this presentation we summarize the main findings of neuroimaging, cognitive, and biochemical measures. Our primary outcome focused on high resolution hippocampal imaging. The findings confirm our previous data showing impairments of hippocampal plasticity in response to bed rest, and adverse effects on spatial cognition. Furthermore, our findings suggest that AG seems to mitigate some of these effects, and deserves further consideration as a countermeasure to reduce neurobehavioral risks during exploration class space mission