Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “REST”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed1998

Effects of prolonged bed rest on cardiovascular oxygen transport during submaximal exercise in humans.

The hypothesis was tested that prolonged bed rest impairs O2 transport during exercise, which implies a lowering of cardiac output Qc and O2 delivery (QaO2). The following parameters were determined in five males at rest and at the steady-state of the 100-W exercise before (B) and after (A) 42-day bed rest with head-down tilt at -6 degrees: O2 consumption (VO2), by a standard open-circuit method; Qc, by the pressure pulse contour method, heart rate (fc), stroke volume (Qh), arterial O2 saturation, blood haemoglobin concentration ([Hb]), arterial O2 concentration (CaO2), and QaO2. The VO2 was the same in A and in B, as was the resting fc. The fc at 100 W was higher in A than in B (+17.5%). The Qh was markedly reduced (-27.7% and -22.2% at rest and 100 W, respectively). The Qc was lower in A than in B [-27.6% and -7.8% (NS) at rest and 100 W, respectively]. The CaO2 was lower in A than in B because of the reduction in [Hb]. Thus also QaO2 was lower in A than in B (-32.0% and -11.9% at rest and at 100 W, respectively). The present results would suggest a down-regulation of the O2 transport system after bed rest.

Adult↗
PubMed1988

The effect of coronary artery bypass grafting on left ventricular systolic function at rest: evidence for preoperative subclinical myocardial ischemia.

Successful coronary artery bypass grafting (CABG) improves exercise-induced left ventricular (LV) dysfunction in patients with coronary artery disease (CAD), but its potential for improving resting LV function remains controversial. To assess the influence of CABG on LV function at rest, 31 CAD patients without previous myocardial infarction were studied before and 6 months after CABG by radionuclide angiography after all cardiac medicines were withdrawn. No patient had angina or ischemic electrocardiographic changes at rest. In 27 patients with patent bypass grafts, CABG significantly increased LV ejection fraction during exercise (47 +/- 11% before to 63 +/- 9% after operation, p less than 0.001), indicating reduction in exercise-induced LV ischemia. Moreover, LV ejection fraction at rest also increased (55 +/- 9 to 60 +/- 8%, p less than 0.001), with 20 of 27 patients manifesting an increase compared with preoperative values. Eleven of these 20 patients had apparently normal LV function at rest (ejection fraction and regional wall motion) before CABG. LV regional ejection fraction was computed by dividing the LV region of interest into 20 sectors. Regional analysis indicated that improved ejection fraction at rest after CABG occurred in regions developing ischemia during exercise before CABG. In 4 patients with occluded grafts, the ejection fraction at rest was unchanged by CABG globally (59 +/- 8 to 58 +/- 9%, difference not significant) and regionally. Thus, LV global and regional function at rest improved after successful CABG, even in patients with normal global LV ejection fraction and no visually detectable wall motion abnormality before surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Calcium absorption, endogenous excretion, and endocrine changes during and after long-term bed rest.

Negative calcium balance is a known consequence of bed rest, and is manifested in elevated urine and fecal calcium (Ca). Elevated fecal Ca can result from either decreased absorption, increased endogenous fecal excretion, or both. We measured the Ca absorption and endogenous fecal excretion in eight healthy male volunteers before and during 4 months of bed rest. Dual isotope (n = 6) or single isotope (n = 2) methods in conjunction with Ca balance were used to calculate true and net Ca absorption and endogenous fecal excretion. Stool Ca increased from 797 mg/day (mean intake 991 mg/day) to 911 mg/day during bed rest, whereas urine Ca excretion increased from 174 to 241 mg/day. True Ca absorption decreased from 31 +/- 7% of Ca intake pre-bed rest to 24 +/- 2% during bed rest, (p < 0.05) and returned toward pre-bed rest values within 5-6 weeks following reambulation. Endogenous fecal excretion did not change significantly, and therefore, most of the increased fecal Ca resulted from changes in absorption. However, in one individual, endogenous fecal Ca excretion was the major contributor to Ca loss. Ionized Ca and pyridinium crosslinks increased and 1,25(OH)2 vitamin D decreased during bed rest, similar to the decrease in Ca absorption; parathyroid hormone (PTH), calcitonin, serum albumin, phosphorus, and total serum Ca were unchanged. Although alkaline phosphatase, osteocalcin, and PTH were unchanged during bed rest, they were elevated during reambulation. These changes accompanied by increased Ca absorption and balance and decreased ionized and total serum Ca suggest a rebound in bone formation following immobilization.

Absorption↗
PubMed2006

How long shall the patient rest before clinic blood pressure measurement?

BACKGROUND: The optimal time at rest before clinic blood pressure (BP) measurement is still undefined. In this study in patients with essential hypertension, the time course of the hemodynamic changes during a 16-min rest in the chair-seated position was evaluated and compared with that observed in a stabilized postural condition, such as after a prolonged supine rest. METHODS: In 55 untreated essential hypertensive patients, BP, heart rate, stroke volume (impedance cardiography), and systemic vascular resistances were measured every other minute during a 16-min rest in the chair-seated position and, in random sequence, in the last 16 min of a 60-min supine rest. RESULTS: Overall, systolic BP (SBP) and diastolic BP (DBP) decreased by 11.6 and 4.3 mm Hg, respectively, during the chair-seated rest; only a 1.8-mm Hg decrease in SBP was observed in the control supine study. The chair-seated fall in BP was associated with a decrease in systemic vascular resistances, in the absence of significant changes in cardiac index. From the logarithmic curve of SBP and DBP decrements, a half-time of 5.8 and 5.5 min respectively, was calculated. Decrements in SBP, but not DBP, were inversely related to the corresponding baseline values. CONCLUSIONS: In untreated essential hypertensive patients a significant decrease in SBP and DBP associated with a systemic vasodilation was observed during a 16-min rest in the chair-seated position. Because approximately 75% of the spontaneous fall in BP occurred within 10 min, it appears that this time at rest before clinic BP evaluation could improve the precision and accuracy of the measurement.

Adult↗
PubMedDate not supplied

Diagnosis of heart failure in older adults: predictive value of dyspnea at rest.

The objective of this study was to describe the predictive value of dyspnea at rest in the diagnosis of heart failure in older adults. We have conducted a retrospective chart review of older adults hospitalized with heart failure in 11 hospitals in Alabama, US. We defined dyspnea at rest as dyspnea not accompanied by activities, sleep, or lying down. We confirmed diagnosis of heart failure using modified Framingham criteria (based on available variables). We estimated values for sensitivity, specificity, predictive value positive and likelihood ratio positive of dyspnea at rest along with their 95% confidence intervals (95% CI). Patients had a mean (+/-S.D.) age 79 (+/-7.5) years, were 60% female and 18% African-American. The prevalence (pre-test probability) of heart failure was 77%. Dyspnea at rest was reported by 975 (89%) patients. Dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea were, respectively, reported by 279 (26%), 356 (33%) and 230 (21%) patients. The sensitivity, specificity and positive predictive value (post-test probability) of dyspnea at rest were, respectively, 92% (95% CI = 90 - 94%), 19% (95% CI = 14 - 24%) and 79% (95% CI = 77 - 82%). Patients with dyspnea at rest were 13% (likelihood = 1.13; 95% CI = 1.06 - 1.20) more likely to have heart failure than those without. Presence of any three of the symptoms of dyspnea at rest, dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, fatigue and lower extremity edema increased the positive predictive value to 90% (95% CI = 87 - 93%). Dyspnea at rest was the commonest symptom among elderly hospitalized HF patients and had high sensitivity, but low specificity and positive predictive value, which increased in the presence of other symptoms.

Aged↗
PubMed2007

Effect of bed rest during pregnancy on bone turnover markers in pregnant and postpartum women.

OBJECTIVE: The aims of our study were to evaluate the changes in bone turnover markers during pregnancy and puerperium as a longitudinal study and to elucidate the effect of bed rest during pregnancy on bone turnover markers in pregnant and postpartum women. METHODS: The study population comprised 27 Japanese pregnant women aged 23-40 years. All women were recruited for the longitudinal study from the outpatients clinic of the Department of Obstetrics and Gynecology, Tokushima University Hospital. Concentrations of serum bone-specific alkaline phosphatase (BAP), urinary cross-linked type I collagen N-telopeptides (NTx), serum NTx and urinary C-terminal telopeptide of type I collagen (CTx) were measured at 10, 26, 30 and 36 weeks of pregnancy and at 4 days and 1 month postpartum. In addition, we recruited 15 pregnant women (aged 25-35 years) who were treated by bed rest before 30 weeks of pregnancy for threatened premature delivery and compared bone turnover markers in these women with those in 22 normal pregnant women (aged 22-39 years). Concentrations of serum BAP, serum NTx, urinary NTx and urinary CTx were measured at 30 and 34 weeks of pregnancy and at 4 days and 1 month postpartum. RESULTS: In the longitudinal study, serum BAP concentration at 1 month postpartum was significantly higher than that at any stage of pregnancy and that at 4 days postpartum. Urinary concentration of NTx increased gradually during pregnancy and showed a peak at 36 weeks of pregnancy, followed by a decrease in the postpartum period. Serum NTx concentration and urinary CTx concentration showed the same patterns of change as that of urinary NTx concentration. In the comparison study, urinary concentrations of NTx and CTx at 30 and 34 weeks of pregnancy in women with bed rest were significantly (p<0.0001 and p<0.001, respectively) higher than those in normal pregnant women. Serum NTx concentration at 34 weeks of pregnancy in women with bed rest was also significantly (p=0.0029) higher than that in normal pregnant women. Serum BAP concentration at 34 weeks of pregnancy in women with bed rest was significantly (p=0.0038) higher than that in normal pregnant women, and these high levels were maintained during puerperium. Serum BAP concentration at 34 weeks of pregnancy was significantly correlated with duration of bed rest (r=0.767, p=0.0041). CONCLUSION: Immobilization due to bed rest during pregnancy is associated with increases in bone turnover markers in pregnant and postpartum women. Concentrations of bone resorption markers increased rapidly at the start of bed rest, while the concentration of a bone formation marker gradually increased toward puerperium.

Adult↗
PubMedDate not supplied

Effects of orientation, intermittent rest and vehicle cleaning during transport on development of transport-related respiratory disease in horses.

The effects of various factors on the inflammatory and stress response in horses during transportation were examined in Experiments 1 and 2, carried out in April and August, respectively. In Experiment 1, three groups (G1-G3) of four Thoroughbreds were used, and in Experiment 2, two groups (G4, G5). G1 animals were loaded into lorries with their heads facing forwards (FF) and given periods of short rest (SR) (30 min for every 4 h driven). G2 horses were loaded facing rearwards (FR) and given SR. G3 horses were FF and given periods of long rest (LR) (2 h rest for every 4 h driven). G4 horses were transported FF with hay suspended in front of them and no cleaning of faeces or urine during rest stops. G5 horses were FF and given pellets instead of hay, and the lorry was cleaned and washed at each rest stop. G4 and G5 horses were rested for 1 h after every 5 h of driving. All groups were driven a distance of 1500 km, and the total journey time was 37 h for G1 and G2, 49 h for G3, and 40 h for G4 and G5. In Experiment 1, indicators of inflammatory and stress responses tended to be highest in G1, intermediate in G2 and lowest in G3. In Experiment 2 they tended to be higher in G4 than in G5. The results suggested that increasing the rest time and cleaning the interior of the vehicle during rest stops reduced transportation stress and respiratory insults, factors that may lead to respiratory disease.

Animal Husbandry↗
PubMed2005

A pre-task resting condition neither 'baseline' nor 'zero'.

This study introduce the comparison of a 'reference state' versus a resting condition (zero), defined upon normative developmental equations. We compared pre-task 'resting' data from healthy individuals with the Normative Cuban digital resting EEG-database recently calculated for VARETA (qEEG/VARETA). The results allowed us to state that a 'pre-task resting conditions' exists as a state beyond the 'zero' or 'baseline' condition. The pre-task 'resting' condition is never truly 'at rest', however most of the previous published fMRI/PET studies assumed such a pre-task condition as reference/baseline condition. By defining different 'resting states' by qEEG/VARETA analyses, we have a potential methodology which can define resting state conditions and to be sure that they are consistent when comparing within group analyses across tasks or between groups either void of task or for task specific conditions.

Adult↗
PubMedDate not supplied

Rest perfusion defects in patients with no history of myocardial infarction predict the presence of a critical coronary artery stenosis.

BACKGROUND: The rest/stress sequence in myocardial perfusion single photon emission computed tomography (SPECT) (MPS) permits evaluation of rest images before stress testing, allowing the identification of unexpected perfusion defects (PDs). We sought to study the angiographic correlates of these resting PDs. METHODS AND RESULTS: This study comprised 139 consecutive patients with no history of myocardial infarction referred for MPS whose stress test was canceled because of the observation of unexpected resting PDs (rest group). Of these, 60 patients (43.2%) were referred for angiography after MPS (6.0 +/- 11.5 days). Angiographic referral rates and results were compared with those of a diagnostic population (n = 3565) who demonstrated stress-induced PDs (stress group) on rest/stress MPS. The mean age in the rest group was 73 +/- 12.5 years, and 73% were men. The frequency of referral for angiography was higher in the rest group (43.2% vs 19.8%, P <.0001). In addition, the rest group more frequently had significant coronary artery disease (CAD) (>/=70%) (95% vs 80%, P =.008) and critical CAD (>/=90%) (80% vs 66%, P =.038). CONCLUSION: The rest/stress sequence for MPS enables the identification of patients with unexpected resting PD, usually resulting from critical CAD, in whom unnecessary stress testing can be avoided.

Aged↗
PubMed1999

Bed rest: a potentially harmful treatment needing more careful evaluation.

BACKGROUND: Bed rest is not only used in the management of patients who are not able to mobilise, but is also prescribed as a treatment for a large number of medical conditions, a procedure that has been challenged. We searched the literature for evidence of benefit or harm of bed rest for any condition. METHODS: We systematically searched MEDLINE and the Cochrane library, and retrieved reports on randomised controlled trials of bed rest versus early mobilisation for any medical condition, including medical procedures. FINDINGS: 39 trials of bed rest for 15 different conditions (total patients 5777) were found. In 24 trials investigating bed rest following a medical procedure, no outcomes improved significantly and eight worsened significantly in some procedures (lumbar puncture, spinal anaesthesia, radiculography, and cardiac catheterisation). In 15 trials investigating bed rest as a primary treatment, no outcomes improved significantly and nine worsened significantly for some conditions (acute low back pain, labour, proteinuric hypertension during pregnancy, myocardial infarction, and acute infectious hepatitis). INTERPRETATION: We should not assume any efficacy for bed rest. Further studies need to be done to establish evidence for the benefit or harm of bed rest as a treatment.

Bed Rest↗
PubMed2003

Short versus prolonged bed rest after uncomplicated acute myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: Recently updated guidelines by the American College of Cardiology/American Heart Association and the European Society of Cardiology recommend at least 12 hours bed rest in patients with uncomplicated myocardial infarction. METHODS: We performed a systematic literature review and meta-analysis of randomized and quasi-randomized controlled trials comparing short versus prolonged bed rest in patients with uncomplicated acute myocardial infarction. RESULTS: We found 15 trials with 1332 patients assigned to a short period of bed rest (range 2 to 12 days) and 1326 patients assigned to prolonged bed rest (range 5 to 28 days). Generally, the studies were outdated and seemed to be of poor methodologic reporting quality. There was no evidence that shorter bed rest was more harmful than longer bed rest in terms of death, reinfarction, post-infarction angina, or thromboembolic events. CONCLUSION: We concluded that bed rest ranging from 2 to 12 days seems to be as safe as longer periods of bed rest.

Aged↗
PubMed2001

Effect of prolonged head-down bed rest on complex cardiovascular dynamics.

We postulated that a change in complex dynamics of the cardiovascular system could be involved in the orthostatic intolerance observed after simulated weightlessness. Supine recordings of 1024 consecutive pulse intervals and systolic blood pressures were obtained on 7 subjects adapted to a 42 day head-down bed rest (day 22 and 42) but also before and 6 days after head-down bed rest (-6 degrees). Coarse graining spectral analysis was used to extract the non-harmonic (fractal) component from each time series. The power spectral densities of this fractal component are inversely proportional to their frequency (1/f beta). We fitted an inverse power law estimate to the fractal component to determine the spectral exponent beta. The complex dynamics of blood pressure and heart rate variability were also analyzed by correlation dimension and non-linear prediction. Bed rest induced orthostatic intolerance in 4 subjects. There was a significant increase in the spectral exponent beta of RR-interval variability during and after head-down bed rest (before: 1.039 +/- 0.090; during: 1.552 +/- 0.080 and 1.547 +/- 0.100; after: 1.428 +/- 0.040). Analysis of the blood pressure dynamics indicated lower correlation dimensions during head-down bed rest and higher coefficients of predictability after head-down bed rest. Complexity alterations of RR-interval and blood pressure variability were not linked with one another during head-down bed rest. These alterations seemed to be correlated with the orthostatic intolerance observed after bed rest. These results suggest a change of the integration level of cardiovascular autonomic regulation.

Adult↗
PubMed1997

Should imaging at stress always be followed by imaging at rest in Tc-99m MIBI SPECT? A proposal for a selective referral and imaging strategy.

OBJECTIVES: We addressed the question whether in patients with cardiac chest pain referred for stress myocardial perfusion scintigraphy, Tc-99m MIBI SPECT stress imaging should always be followed by a rest imaging procedure. BACKGROUND: Using Tc-99m MIBI imaging a stress rest sequence is usually performed implying that the resting study always follows the stress study irrespective of the results of the stress study. As a normal stress study would eliminate a subsequent resting study, it appears desirable to potentially define certain subsets of patients in whom a normal stress study can be expected in order to determine a more selective referral approach to the nuclear medicine department. The consequences of such a more streamlined approach would less impose on the logistics of the department of nuclear medicine, with decrease of investigation time, radiation dose, and costs in a time of retrenchment in the medical sector. METHODS: A consecutive series of 460 patients (mean age 58.2 years) was studied who were stratified to 269 patients without prior myocardial infarction, and to 191 patients with documented evidence of a previously sustained myocardial infarction. All patients underwent Tc-99m MIBI SPECT imaging according to a two-day stress-rest protocol. RESULTS: Patients with and without a previous myocardial infarction showed suboptimal overall predictive accuracies for the exercise electrocardiograms (58% and 60%, respectively). In the total group of 460 patients, 94 (20%) patients showed a normal stress-rest Tc-99m MIBI SPECT; this occurred in 86/269 (32%) patients without a previous myocardial infarction and in only 8/191 (4%) patients with a previous myocardial infarction. CONCLUSIONS: Patients with a stress defect at Tc-99m MIBI SPECT imaging should always undergo a resting SPECT study irrespective of the clinical and stress electrocardiographic findings. As patients without a previous myocardial infarction had a normal stress SPECT study in almost one-third (32%) of patients compared to only 4% in patients with a previously myocardial infarction, it may be useful to employ different referral and imaging strategies i.e., a stress-only versus a stress-rest procedure. To schedule referring patients differently according to the presence or absence of a previously sustained myocardial infarction may be cost-saving, less demanding for the nuclear medicine personnel, and patient-convenient. In addition, a stress-only imaging procedure reduces radiation exposure to the individual patient.

Adult↗
PubMed2002

Fluid volume compartments and biochemical measurements for disclosing fluid depletion during acute and rigorous bed rest in normal subjects.

Rigorous bed rest (RBR) induces fluid depletion, however, little is known about the mechanisms of development of fluid depletion during acute bed rest (ABR). Measuring fluid retention and body hydration parameters, the aim of this study was to establish whether ABR than RBR could depress significantly more fluid retention contributing to greater fluid depletion development. Studies were conducted during pre bed rest (BR) period of three days and during seven days period of ABR and RBR. Thirty normal male individuals aged, 24.2 +/- 5.0 years chosen as subjects. They were divided into three groups: unrestricted ambulatory control subjects (UACS), acute bed rested subjects (ABRS) and rigorous bed rested subjects (RBRS). Acute bed rested subjects confined abruptly to RBR, while they did not have any prior knowledge of the exact date and time when they would be asked to stay in bed. Rigorous bed rested subjects submitted to RBR on a predetermined date and time known to them right from the start of the study. Unrestricted ambulatory control subjects were not confined to any type of bed rest. Fluid loss, urinary and plasma sodium (Na+) and potassium (K+), urinary osmolality and plasma osmolality, whole blood hematocrit (Hct), whole blood hemoglobin (Hb), and total plasma protein increased significantly (p < 0.05) with time, while fluid retention, extracellular volume (ECV), plasma volume (PV), red cell volume (RCV), blood volume (BV), interstitial volume (IV) and fluid intakes reduced significantly (p < 0.05) with time in ABRS and RBRS compared with their pre-BR values and the control values (UACS). However, the measured parameters changed significantly (p < 0.05) more with time in ABRS than RBRS. Fluid rention, fluid loss, fluid intake, urinary and plasma Na+ and K+, Hct, Hb, plasma protein, urinary and plasma osmolality, ECV, PV, RCV, BV and IV did not change in UACS compared with their pre-BR values. It was concluded that significant increase of urinary and plasma osmolality, whole blood Hct and Hb, total plasma protein, plasma Na+ and K+, and significant decrease of ECV, PV, RCV, BV, and IV may demonstrate fluid depleteion, while a higher increase of fluid loss in spite of fluid depletion may show decreased fluid retention. Dissociation between fluid losses and fluid depletion may suggest the presence of impair fluid retention as a mechanism of development of fluid depletion.

Adult↗
PubMed1997

Site of insulin resistance after surgery: the contribution of hypocaloric nutrition and bed rest.

1. Insulin resistance after surgery has been shown to be related to several important derangements in protein and fat metabolism. However, mechanisms of impaired glucose tolerance after surgery remain ill-defined. 2. Insulin sensitivity and glucose kinetics (6,6(2)H2-glucose) were studied in seven patients before and after elective surgery (surgery group), by two step-hyperinsulinaemic (0.3 and 0.8 munits kg-1 min-1), normoglycaemic (4.5 mmol/l) clamps. Six healthy subjects were studied, using the same protocol, before and after a similar period of bed rest and hypocaloric nutrition (fast/bed rest group) to delineate the effects of surgery per se. 3. Basal endogenous glucose production and whole-body glucose disposal was higher after surgery (P < 0.001), whereas no change was found after fast/bed rest. During glucose clamps, the glucose infusion rates required to maintain normoglycaemia and whole-body glucose disposal decreased (P < 0.001) after surgery, while endogenous glucose production increased (P < 0.001). In the control subjects, levels of endogenous glucose production remained unchanged after fast/bed rest. In contrast, glucose infusion rates and whole-body glucose disposal during glucose clamps also decreased after fast/bed rest (P < 0.01). However, the relative decrease in both these parameters was greater after surgery compared with after fast/bed rest (P < 0.01). 4. After surgery, energy expenditure and fat oxidation increased (P < 0.001), whereas glucose oxidation decreased (P < 0.05). No significant change was found in glucose utilization postoperatively. After fast/bed rest, no change was found in energy expenditure. However, fat oxidation increased (P < 0.01), whereas glucose oxidation and glucose utilization decreased (P < 0.05). 5. In conclusion, impaired glucose tolerance develops after surgery as a result of decreased insulin-stimulated whole-body glucose disposal as well as increased endogenous glucose release. Despite the increase in endogenous glucose production, the reduction in endogenous glucose production with each elevation of insulin was unaffected by surgery. Perioperative bed rest and/or hypocaloric nutrition contribute to the decrease in insulin-stimulated whole-body glucose disposal in the post-operative state, whereas these factors have no effects on endogenous glucose production.

Adult↗
PubMed2004

Glycogen in the brain of Drosophila melanogaster: diurnal rhythm and the effect of rest deprivation.

One function of sleep is thought to be the restoration of energy stores in the brain depleted during wakefulness. One such energy store found in mammalian brains is glycogen. Many of the genes involved in glycogen regulation in mammals have also been found in Drosophila melanogaster and rest behavior in Drosophila has recently been shown to have the characteristics of sleep. We therefore examined, in the fly, variation in the glycogen contents of the brain, the whole head and the body throughout the rest/activity cycle and after rest deprivation. Glycogen in the brain varies significantly throughout the day (p=0.001) and is highest during rest and lowest while flies are active. Glycogen levels in the whole head and body do not show diurnal variation. Brain glycogen drops significantly when flies are rest deprived for 3 h (p=0.034) but no significant differences are observed after 6 h of rest deprivation. In contrast, glycogen is significantly depleted in the body after both 3 and 6 h of rest deprivation (p<0.0001 and p<0.0001, respectively). Glycogen in the fly brain changes in relationship to rest and activity and demonstrates a biphasic response to rest deprivation similar to that observed in mammalian astrocytes in culture.

Animals↗
PubMed2006

Highly demanding resistive vibration exercise program is tolerated during 56 days of strict bed-rest.

Several studies have tried to find countermeasures against musculoskeletal de-conditioning during bed-rest, but none of them yielded decisive results. We hypothesised that resistive vibration exercise (RVE) might be a suitable training modality. We have therefore carried out a bed-rest study to evaluate its feasibility and efficacy during 56 days of bed-rest. Twenty healthy male volunteers aged 24 to 43 years were recruited and, after medical check-ups, randomised to a non-exercising control (Ctrl) group or a group that performed RVE 11 times per week. Strict bed-rest was controlled by video surveillance. The diet was controlled. RVE was performed in supine position, with a static force component of about twice the body weight and a smaller dynamic force component. RVE comprised four different units (squats, heel raises, toe raises, kicks), each of which lasted 60 - 100 seconds. Pre and post exercise levels of lactate were measured once weekly. Body weight was measured daily on a bed scale. Pain questionnaires were obtained in regular intervals during and after the bed-rest. Vibration frequency was set to 19 Hz at the beginning and progressed to 25.9 Hz (SD 1.9) at the end of the study, suggesting that the dynamic force component increased by 90 %. The maximum sustainable exercise time for squat exercise increased from 86 s (SD 21) on day 11 of the BR to 176 s (SD 73) on day 53 (p = 0.006). On the same days, post-exercise lactate levels increased from 6.9 mmol/l (SD2.3) to 9.2 mmol/l (SD 3.5, p = 0.01). On average, body weight was unchanged in both groups during bed-rest, but single individuals in both groups depicted significant weight changes ranging from - 10 % to + 10 % (p < 0.001). Lower limb pain was more frequent during bed-rest in the RVE subjects than in Ctrl (p = 0.035). During early recovery, subjects of both groups suffered from muscle pain to a comparable extent, but foot pain was more common in Ctrl than in RVE (p = 0.013 for plantar pain, p = 0.074 for dorsal foot pain). Our results indicate that RVE is feasible twice daily during bed-rest in young healthy males, provided that one afternoon and one entire day per week are free. Exercise progression, mainly by progression of vibration frequency, yielded increases in maximum sustainable exercise time and blood lactate. In conclusion, RVE as performed in this study, appears to be safe.

Adult↗
PubMed1989

Glycogen synthesis during exercise and rest with carbohydrate feeding in males and females.

Since it has been demonstrated that endurance-trained cyclists are able to synthesize glycogen during mild exercise, glycogen synthesis was investigated in non-endurance-trained males and females as well. Seven males and nine females exercised on a cycle ergometer to deplete muscle glycogen. After the exhaustive exercise and taking a muscle biopsy, the males either exercised 2.5 h at 40% of maximal work load (trial A) or rested for 2.5 h (trial B). In both trials the subjects drank a 25% maltodextrin-fructose solution. After 2.5 h of exercise or rest, a second muscle biopsy was taken for determination of glycogen and for histochemistry (ATPase and PAS). In the females glycogen synthesis was only studied during 2.5 h rest, after prior glycogen depletion. In the male subjects, during mild exercise with carbohydrate feeding muscle glycogen did not increase. During rest muscle glycogen increased in the males from 123 +/- 49 mmol/kg DW at exhaustion to 229 +/- 70 mmol/kg DW (P less than 0.001), resulting in a net increase of 42 mmol/kg DW/h. Glycogen synthesis during rest occurred both in type I and type II fibers. In the females, during 2.5 h of rest, muscle glycogen increased from 130 +/- 56 mmol/kg DW at exhaustion to 224 +/- 51 mmol/kg DW, resulting in a net increase of 37 mmol/kg DW/h. The results demonstrate that glycogen synthesis during mild exercise does not occur in non-endurance-trained athletes, whereas in the resting state glycogen synthesis in non-endurance-trained males is not different from endurance-trained cyclists. In addition, glycogen synthesis during rest is similar in males and females.

Adult↗