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PubMed2003

The associations between physical activity and inflammatory markers in high-functioning older persons: MacArthur Studies of Successful Aging.

OBJECTIVES: To determine the relationships between recreational activity, house/yard work activity, work activity, and total physical activity and high levels of two peripheral blood markers of inflammation: interleukin-6 (IL-6) and C-reactive protein (CRP). DESIGN: Cross-sectional study. SETTING: Three communities (Durham, NC; New Haven, CT; and East Boston, MA). PARTICIPANTS: Eight hundred seventy persons aged 70 to 79 who were in the top third of community-dwelling older persons with respect to physical and cognitive functioning. MEASUREMENTS: Blood levels of IL-6 and CRP and self-reported recreational activity, house/yard work activity, work activity, and total physical activity. RESULTS: The adjusted odds ratios (AORs) for individuals with high levels of recreational activity to have values in the top tertiles of IL-6 and CRP were 0.65 (95% confidence interval (CI) = 0.48-0.87) and 0.70 (95% CI = 0.51-0.95), respectively. The AORs for those with a high level of house/yard work activity to have values in the top tertile of IL-6 and CRP were 0.90 (95% CI = 0.67-1.20) and 0.70 (95% CI = 0.50-0.96), respectively. High levels of house/yard work and recreational activity were independently associated with lower risk of high CRP. CONCLUSION: The association between high levels of recreational activity and lower levels of the inflammatory markers IL-6 and CRP suggests a mechanism for its protective effect and supports interventions that increase physical activity in older persons. Such potential benefits of increased physical activity on inflammatory markers will need to be confirmed in clinical trials.

Aged↗
PubMed2001

Physical exercise and/or enriched foods for functional improvement in frail, independently living elderly: a randomized controlled trial.

OBJECTIVE: To examine the effects of an exercise program and an enriched food regimen on physical functioning of frail elderly persons. DESIGN: A 17-week randomized, placebo-controlled trial. SETTING: Community. PARTICIPANTS: One hundred fifty-seven independently living frail elderly (mean age, 78.7 +/- 5.6yr). INTERVENTION: Thirty-nine subjects participated in a twice weekly group exercise designed to improve daily functioning; 39 subjects daily ate foods enriched with vitamins and minerals (at 25%-100% of the recommended daily allowances); 42 subjects exercised and ate enriched foods; and 37 subjects served as controls. Nonexercising groups followed a social program; nonsupplement groups received the same food products without the micronutrients. MAIN OUTCOME MEASURES: Functional performance based on 6 performance tests, physical fitness based on 7 fitness tests, and disabilities based on the self-reported ability to perform 16 daily activities. RESULTS: Performance sum scores were significantly enhanced in trained (+8%) compared with nontrained subjects (-8%) (difference in change: 1.9 points, p < .001, adjusted for baseline scores). Fitness sum scores were significantly enhanced as well (+3% in trained vs -2% in nontrained) (difference in change: 0.9 points, p = .05, adjusted for baseline scores). No exercise effects on the disability score were observed. Consumption of enriched products did not affect performance, fitness, or disability scores. CONCLUSION: Our comprehensive exercise program, designed for widespread applicability, enhanced physical performance and fitness in a population of frail elderly. Daily consumption of micronutrient enriched foods showed no functional benefits within 17 weeks.

Activities of Daily Living↗
PubMed1998

The effect of dietary creatine supplementation on skeletal muscle metabolism in congestive heart failure.

AIMS: To assess the effects of dietary creatine supplementation on skeletal muscle metabolism and endurance in patients with chronic heart failure. METHODS: A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction was measured using handgrip dynanometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of maximum voluntary contraction or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg and 21 kg. Patients were assigned to creatine 20 g daily or matching placebo for 5 days and returned after 6 days for repeat study. RESULTS: Contractions (median (25th, 75th interquartiles)) until exhaustion at 75% of maximum voluntary contraction increased after creatine treatment (8 (6, 14) vs 14 (8, 17), P = 0.025) with no significant placebo effect. Ammonia per contraction at 75% maximum voluntary contraction (11.6 mumol/l/contraction (8.3, 15.7) vs 8.9 mumol/l/contraction (5.9, 10.8), P = 0.037) and lactate per contraction at 75% maximum voluntary contraction (0.32 mmol/l/contraction (0.28, 0.61) vs 0.27 mmol/l/contraction (0.19, 0.49), P = 0.07) fell after creatine but not after placebo. CONCLUSIONS: Creatine supplementation in chronic heart failure augments skeletal muscle endurance and attenuates the abnormal skeletal muscle metabolic response to exercise.

Aged↗
PubMed2006

On the origin of genetics and beginnings of medical genetics of diseases of the kidney.

The twentieth century has been termed the century of the gene. Although the term "gene" was introduced in 1909, interest in reproduction and heredity has occupied humankind since its transition from hunter-gatherers to farmers and herders. Heredity, as it applies to diseases, began with Greek medicine. The humoral theory of the Hippocratic Corpus provided an etiological explanation for susceptibility of individuals to certain diseases well into the nineteenth century and was variously termed diathesis, temperament, and constitution. The application of the new probability math to quantify the hybridization of sweet peas by Gregor Mendel (1822-1884) in 1866 provided a scientific basis to inheritance, which had theretofore been an amalgam of scattered empirical observations. The near simultaneous publication of Origin of Species by Charles Darwin (1809-1882) in 1859 was a key catalyst in the transfer of what had been studies in plant biology into studies of populations and humans. The subsequent growth of genetics has been the outcome of interplay of technological breakthroughs in statistical analysis, cytology, biochemistry, physics, and computer science, coupled with the insightful analysis of workers in the field, several of whom have been the recipients of the Nobel Prize in medicine or chemistry since 1933. Application of these techniques to molecular biology and medical genetics is just beginning to yield insight into diseases of the kidney and provide visions of their likely therapies in the future.

Genetics, Medical↗
PubMed1999

Hand function following single ray amputation.

We retrospectively studied primary and reconstructive single ray resection at 16 to 150 months after surgery (median, 41 months) in 25 patients (18 males) whose average age was 28 years. Cases were reviewed 16 to 154 months after surgery (median, 41 months). The injuries involved 14 dominant and 11 nondominant hands. Twelve patients had primary ray resection (< or =2 weeks after injury) and 13 had secondary/reconstructive amputation of 18 border and 7 central digits. Examinations and functional testing by Minnesota rate of manipulation and timed grooved pegboard tests were done and x-rays were reviewed. The majority of patients were subjectively satisfied with the appearance and function of the hand. Patients lost an average of 13 weeks of work (range, 2-24 weeks); those with primary resection were out of work 9 weeks (range, 2-17 weeks) and patients who had secondary resection lost a total of 16 weeks of work (range, 7-24 weeks). Twenty-one of the 25 patients returned to their preinjury occupation. Evaluation of nonwork plus settled workers' compensation cases versus nonsettled compensation/litigation cases showed that there were statistically significant differences in grip strength, key pinch, oppositional pinch, and Minnesota rate of manipulation test results. Primary ray removal limits the total costs associated with injury and disability; unsettled compensation/litigation issues produce statistically disparate and otherwise physically inexplicable differences.

Adolescent↗
PubMed2000

Comparative responsiveness of Short-Form 12 and Minnesota Living With Heart Failure Questionnaire in patients with heart failure.

BACKGROUND: The Short-Form 12 (SF-12) and Living With Heart Failure Questionnaire (LHFQ) are commonly used to measure quality of life (QOL) in heart failure outcomes research. Their comparative responsiveness, however, has not been documented. METHODS AND RESULTS: A prospective cohort study was conducted among patients attending a university-based heart failure clinic between April 1997 and September 1998. All patients received comprehensive heart failure care management. QOL of patients was assessed by the SF-12 and LHFQ at baseline and 3 months. Of 87 patients completing follow-up, the mean change score was 10.1 for the LHFQ and 5.8 for the SF-12 (both Ps < .001). The change scores of the instruments were correlated (r = 0.61; P < .001). The SF-12 had a greater ability than the LHFQ to statistically detect change in physical health but was less sensitive to changes in mental health. The LHFQ performed better than the SF-12 in the ability to distinguish the differences in perceived global health transition. CONCLUSION: The LHFQ is more responsive than the SF-12 to changes in QOL. The SF-12 should not be used alone to measure the changes in QOL of patients with heart failure.

Adult↗
PubMed2002

Exercise intensity of cycle-touring events.

The aim of the study was to analyze the exercise intensity of recreational cyclists participating in a cycling-touring event. In 14 male healthy recreational cyclists heart rate (HR) monitoring was performed during the Otztal Radmarathon 1999 (distance: 230 km; altitude difference: 5500 m) in order to evaluate the HR response and to estimate the cardiopulmonary strains for the less-trained athlete confronted with such a marathon. Four different exercise intensities were defined as percentages of maximal HR (HR(max)) as follows: recovery HR (HR(re)) < 70 % of HR max; moderate aerobic HR (HR(ma)) = 70 - 80 %; intense aerobic HR (HR(ia)) = 80 - 90 %; and anaerobic HR (HR(an)) > 90 %. All athletes finished the competition successfully. The mean racing time was 10 h 14 min, the average speed 22.5 km/h. The mean HR(max) was 188 bpm, the average value of the measured HRs (HR(average)) was 145 bpm resulting in a mean HR(average)/HR(max) ratio of 0.77. Athletes spent 18.5 % (1 h 54 min) of total race time within HR(re), 28 % (2 h 52 min) within HR(ma), 39.5 % (4 h 02 min) within HR(ia), and 14 % (1 h 26 min) within HR(an). The vast majority of exercise was done under "aerobic conditions" (HR(re) + HR(ma) + HR(ia) = 86 % or 8 h 48 min) - confirming the knowledge that the aerobic energy supply is crucial for the performance of long-term exercise. The large amount of high exercise intensities (HR(ia) + HR(an) = 53.5 % or 5 h 30 min), however, features the intense cardiopulmonary strains evoked by such competitions. The HR response was related to the course profile with HRs significantly declining in all subjects to an extent of 10 % during the course of race. Our findings show that the exercise intensity borne by recreational cyclists during a cycle-touring event is high and very similar to that of professionals. With respect to the high cardiovascular strains a thorough medical screening is advisable for any participant of such an event combining both high volume and high intensity loads.

Adult↗
PubMed2002

Markers of coagulation, fibrinolysis and angiogenesis after strenuous short-term exercise (Wingate-test) in male subjects of varying fitness levels.

It was the aim of the study to analyse the haemostatic system during a high standardized intensive short-term (30 s) exercise (anaerobic Wingate test). Blood samples were taken from 15 male subjects before (t0 ), and within 2 (t1 ), 9 (t2 ) and 30 min (t3 ) after the test. We found that the partial thromboplastin time was markedly shortened, whereas the prothrombin time increased slightly from t0 to t1 (p < 0.002) and remained elevated (t3, p < 0.046). Factor VIII increased from t0 to t1 (p < 0.001) and remained elevated as well (t3, p < 0.001). Fibrin monomers were approximately 15 times higher immediately post-exercise (t1, p < 0.001) and continued to be elevated (t3, p < 0.004). The tissue plasminogen activator increased by 4 times after exercise (t1, p < 0.001) and remained elevated (t3, p < 0.002). The d-dimers increased from t0 to t1 (p < 0.001) as well and remained elevated (t3, p < 0.005). Thrombopoietin concentrations were unchanged, whereas the vascular endothelial growth factor increased immediately post-exercise (t0 to t1, p < 0.011 resp. at t2 p < 0.019) and returned to the control level at t3 (p < 0.878). In conclusion, it was found that prothrombotic markers and, even more pronounced, those of the fibrinolytic system were increased. The study provides evidence that due to intensive short-term exercise the balance of the haemostatic system is shifted to a higher equilibrium. Theoretically, the data show that in the case of a subject with risk factors such as impaired fibrinolysis, unfavourable conditions cannot be excluded.

Adult↗
PubMed2004

Age-related differences in growth hormone (GH) regulation during strenuous exercise.

This study was designed to investigate the central neuroendocrine mechanisms by which exercise (EX) stimulates growth hormone (GH) release as a function of age. Twelve male subjects, six in their early-to-mid twenties and six in their late sixties or seventies, received a strong GH stimulus either as incremental EX until volitional exhaustion or by administration of GHRH alone or Hex alone two hours after a presumed maximal GH response to combined administration of GHRH plus hexarelin (Hex). Total GH availability was calculated as area under the curve (AUC) over time periods 0 - 120 and 120 - 240 min. The mean AUC in micro g/l x 120 min to GHRH+Hex in the younger group was approximately twice that in the older group (11,260, range 3,947 - 19,007 vs. 5,366, range 2,262 - 8,654). In younger males, the mean AUC to EX (509, range 0 - 1,151) was larger than to GHRH (119, range 0 - 543), but less than that to Hex (919, range 0 - 1,892). In the older group, GH responses to EX and GHRH were abolished (mean AUC: 112, range 0 - 285, and 156, range 30 - 493), respectively) in contrast to the response to Hex (1,077, range 189 - 1,780). These data indicate that maximal GH stimulation by GHRH+Hex results in greater desensitization of GHRH compared to Hex, irrespective of age. We postulate that the abolished responsiveness of GH to EX in older group is due to insufficient disinhibition of hypothalamic somatostatin activity and desensitization of GHRH, while the preserved activity of a central Hex-related pathway is not involved. The GH response to EX in younger males is due to complete inhibition of somatostatin activity and stimulation of a central Hex-related pathway in spite of GHRH desensitization. We conclude that a central Hex-related pathway is the primary factor for EX-induced GH release only in younger males.

Adult↗
PubMed2006

Heart rate variability and performance at two different altitudes in well-trained swimmers.

UNLABELLED: The aim of this study was to compare the effects of training at two different altitudes on heart rate variability (HRV) and performance in well-trained swimmers. Eight national-level male swimmers (age = 17.0 +/- 1.8 yrs, weight = 67.0 +/- 6.6 kg, height = 180.4 +/- 7.2 cm, V(O2max) = 60.4 +/- 4.0 ml.min(-1). kg(-1)) trained 17 days at 1200 m altitude (T1200), then, after 6 weeks of moderate training at sea level, reproduced the same training plan at 1850 m (T1850). The training was mainly aerobic with 86 % and 84 % < or = anaerobic threshold for T 1200 and T1850, respectively. Four HRV analysis tests were performed during T1200 and T1850, respectively (pre-test = day 0, test 2 = day 5, test 3 = day 11, post-test = day 17), in supine and standing position. Performance was measured over a 2000-m freestyle test at the altitude of 1200 m. A difference in HRV changes was observed between the two altitudes: during T1200, addition of parasympathetic and sympathetic activity in supine (TP(SU)) (p < 0.05) and standing (TP(ST)) (p < 0.05) position, supine parasympathetic activity (HF(SU)) (p < 0.05), and standing sympathetic activity (LF(ST)) (p < 0.05) were increased and the 2000-m performance was improved (p < 0.05) whereas none of these parameters was changed during T1850. Change in performance was correlated with increase in HF(SU) (r = 0.73; p < 0.05) and tended towards correlation with increase in LF(ST) (r = 0.73; p = 0.06). CONCLUSION: the same training loads induced a positive effect on HRV and performance at 1200 m but not at 1850 m. This may be the consequence of greater stress due to an interaction between greater hypoxic stimulus and the same training loads. These results highlight two opposing effects: aerobic training increases, whereas hypoxia decreases HF(SU), due to the correlation between HRV and changes in performance during altitude training.

Adolescent↗
PubMed2006

The 24 h urinary cortisol/cortisone ratio and epinephrine/norepinephrine ratio for monitoring training in young female tennis players.

The effect of training variations on the 24 h urinary cortisol/cortisone (C/Cn) ratio and the epinephrine/norepinephrine (E/NE) ratio in relation with mood (evaluated using the Brunel Mood Scale: BRUMS) and performance was investigated in seven trained young female tennis players (12.8 +/- 1.7 years). Like the proposed model in adults, the monitoring of hormonal and mood parameters could be a useful index in training follow-up in young sportswomen. Assessment of nutritional intake, nitrogen excretion rate and nitrogen balance were also determined to measure the dietary practice of these athletes. Nitrogen balance was calculated from the mean daily protein intake and the urinary nitrogen excretion. Data were collected after a 1-month rest (September, T1), 3 months after T1 (after technical and endurance training: December, T2) and 7 months after T1 (after 4 months of increasing-volume/high-intensity training: March, T3). A significant increase in C/Cn ratio (+ 30 %, p < 0.05) were noted from T1 to T3. In the same time, urinary NE concentrations decreased significantly. The E/NE ratio increased from T1 to T2 and decreased at T3 (T1 vs. T3: - 30 %, p < 0.05). The BRUMS inventory at T3 reflected changes in specific mood states with a significant increase in fatigue and anger scores, while vigor scores decreased significantly compared to T1. This period also corresponded with the lowest percentage of matches won and with the highest training load. Energy intake was about 16 % lower than the French recommendations for girls of the same age. However, a positive nitrogen balance was observed from a mean intake of 1.0 g x kg (-1) x day (-1). Our results reveal that an increase of overnight urinary C/Cn ratio and a decrease of E/NE ratio are concomitant with alterations in mood state and performance, all these parameters being associated with physical and psychological stress.

Affect↗
PubMed1997

Paced effort and all-out 30-second power tests.

The purpose of this study was to determine whether mean power output in 30 seconds was greater in a paced effort test or an all-out effort under optimal loading conditions. Nine male athletes volunteered to participate. All testing was done on a Monark cycle ergometer with continuous measurement of velocity and resistance. Power output was calculated (Resistance x Velocity) and corrected for acceleration of the flywheel. For each subject, optimal resistance for peak power output was determined with 5 brief (7-second) tests. Subsequently, 3 all-out 30-second tests using 80, 90 and 100% of this estimated optimal resistance, then 3 paced effort 30-second tests were completed on separate days. Pacing was accomplished with velocity feedback at 80, 100 or 120% of optimal velocity calculated from the all-out tests. Subjects were encouraged to try to exceed the target velocity if possible during the final 10 seconds of the paced effort test. The best all-out test (772 +/- 35 W) was not different (paired t test, p = 0.31) from the best paced effort test (787 +/- 27 W). Furthermore, there was no significant difference between mean power output in the all-out tests at 90% (736 +/- 28 W) and 100% (766 +/- 36 W) of estimated optimal resistance for peak power output (1.16 +/- 0.05 N x kg[-1]), but mean power at 80% of the estimated optimal resistance was lower (722 +/- 31 W; ANOVA for repeated measures, p < 0.05). In conclusion, a paced effort test does not permit greater mean power output over 30 seconds than an all-out test, and there is considerable latitude in apparent optimal resistance for mean power output in a 30-second test.

Analysis of Variance↗
PubMed1997

Physical activity and fitness in patients with headache disorders.

Recent studies indicate that aerobic activities might reduce severity and/or frequency of migraine attacks. The present study was intended to investigate whether physical activities and fitness (aerobic endurance, flexibility, and muscle strength endurance) as well as body composition are different in patients with headache disorders and healthy control subjects. The study included 56 patients (aged 17-64 years) with headache disorders (migraine, tension-type, cluster, analgetics abuse, and other types of headache) and 145 age-matched volunteers without history of recurrent or chronic headache. A standardized questionnaire revealed similar self-esteem of physical activities in both groups. Objective physical fitness testing in a representative sample of 22 patients and 36 control subjects showed significantly reduced aerobic endurance in female and male patients as well as reduced flexibility in female patients as compared to control subjects, whereas muscle strength endurance was not significantly different between both groups. Female patients presented with a significantly higher total body fat as compared to control subjects. In conclusion, headache patients turned out to be less physically fit than control subjects. There was a discrepancy between self-esteem and objective test results regarding physical activity and fitness in patients with headache disorders.

Adolescent↗
PubMed2002

Coherent structures and self-consistent transport in a mean field Hamiltonian model.

A study of coherent structures and self-consistent transport is presented in the context of a Hamiltonian mean field, single wave model. The model describes the weakly nonlinear dynamics of marginally stable plasmas and fluids, and it is related to models of systems with long-range interactions in statistical mechanics. In plasma physics the model applies to the interaction of electron "holes" and electron "clumps," which are depletions and excesses of phase-space electron density with respect to a fixed background. In fluid dynamics the system describes the interaction of vortices with positive and negative circulation in a two-dimensional background shear flow. Numerical simulations in the finite-N and in the N--> infinity kinetic limit (where N is the number of particles) show the existence of coherent, rotating dipole states. We approximate the dipole as two "macroparticles" (one hole and one clump) and consider the N=2 limit of the model. We show that this limit has a family of symmetric, rotating integrable solutions described by a one-degree-of-freedom nontwist Hamiltonian. A perturbative solution of the nontwist Hamiltonian provides an accurate description of the mean field and rotation period of the dipole. The coherence of the dipole is explained in terms of a parametric resonance between the rotation frequency of the macroparticles and the oscillation frequency of the self-consistent mean field. This resonance creates islands of integrability that shield the dipole from regions of chaotic transport. For a class of initial conditions, the mean field exhibits an elliptic-hyperbolic bifurcation that leads to the filamentation, chaotic mixing and eventual destruction of the dipole. (c) 2002 American Institute of Physics.

Journal Article↗
PubMed2004

Coping with the node problem in quantum hydrodynamics: the covering function method.

A conceptually simple approach, the covering function method (CFM), is developed to cope with the node problem in the hydrodynamic formulation of quantum mechanics. As nodes begin to form in a scattering wave packet (detected by a monitor function), a nodeless covering wave function is added to it yielding a total function that is also nodeless. Both local and global choices for the covering function are described. The total and covering functions are then propagated separately in the hydrodynamic picture. At a later time, the actual wave function is recovered from the two propagated functions. The results obtained for Eckart barrier scattering in one dimension are in excellent agreement with exact results, even for very long propagation times t=1.2 ps. The capability of the CFM is also demonstrated for multidimensional propagation of a vibrationally excited wave packet.

Biophysics↗
PubMed2005

Stochastic multiresonance in the coupled relaxation oscillators.

We study the noise-dependent dynamics in a chain of four very stiff excitable oscillators of the FitzHugh-Nagumo type locally coupled by inhibitor diffusion. We could demonstrate frequency- and noise-selective signal acceptance which is based on several noise-supported stochastic attractors that arise owing to slow variable diffusion between identical excitable elements. The attractors have different average periods distinct from that of an isolated oscillator and various phase relations between the elements. We explain the correspondence between the noise-supported stochastic attractors and the observed resonance peaks in the curves for the linear response versus signal frequency.

Diffusion↗
PubMed2005

Transition probabilities of a string oscillator subject to impulsive collisions with a heavy mass point.

Impulsive linear collisions between a string oscillator (a one-dimensional particle in a box) and a mass point are studied quantum mechanically. In the limit of a very heavy mass point (which corresponds classically to many collisions during a single encounter) the transition probabilities are determined exactly. The result permits a discussion of the mixed quantum-classical regime where the collider becomes almost classical while the oscillator remains quantum mechanical. While the average transition probabilities P(m-->n) are well reproduced by the Ehrenfest mean-field approximation, the prediction for the superimposed high-frequency resonance structure is qualitatively wrong for a genuine quantum oscillator. Only if the oscillator is also almost classical and if (m-n)2 square root(mu) << m, where mu is the mass ratio collider/oscillator, this structure is correctly predicted by the Ehrenfest approximation.

Chemistry, Physical↗