Showing papers in "Journal of Applied Physiology in 1997"
TL;DR: Both men and women experience age-related losses in isometric, Con, and Ecc knee extensors peak torque; however, age accounted for less of the variance in Ecc peak torque in women, and women tend to better preserve muscle quality with age for Eccpeak torque.
Abstract: Lindle, R. S., E. J. Metter, N. A. Lynch, J. L. Fleg, J. L. Fozard, J. Tobin, T. A. Roy, and B. F. Hurley. Age and gender comparisons of muscle strength in 654 women and men aged 20–93 yr.J. Appl. ...
927 citations
TL;DR: The hypotheses that skeletal muscle is reduced in the elderly and that whole body 40K counting-derived total body potassium (TBK) provides a reasonable indirect assessment of skeletal muscle mass are supported.
Abstract: Gallagher, Dympna, Marjolein Visser, Ronald E. De Meersman, Dennis Sepulveda, Richard N. Baumgartner, Richard N. Pierson, Tamara Harris, and Steven B. Heymsfield. Appendicular skeletal muscle mass: effects of age, gender, and ethnicity. J. Appl. Physiol. 83(1): 229–239, 1997.—This study tested the hypothesis that skeletal muscle mass is reduced in elderly women and men after adjustment first for stature and body weight. The hypothesis was evaluated by estimating appendicular skeletal muscle mass with dual-energy X-ray absorptiometry in a healthy adult cohort. A second purpose was to test the hypothesis that whole body40K counting-derived total body potassium (TBK) is a reliable indirect measure of skeletal muscle mass. The independent effects on both appendicular skeletal muscle and TBK of gender (n = 148 women and 136 men) and ethnicity (n = 152 African-Americans and 132 Caucasians) were also explored. Main findings were 1) for both appendicular skeletal muscle mass (total, leg, and arm) and TBK, age was...
884 citations
TL;DR: It is demonstrated that strike-interval fluctuations are more random (i.e., less correlated) in elderly subjects and in subjects with Huntington's disease, which are apparently associated with changes in central nervous system control.
Abstract: Fluctuations in the duration of the gait cycle (the stride interval) display fractal dynamics and long-range correlations in healthy young adults. We hypothesized that these stride-interval correlations would be altered by changes in neurological function associated with aging and certain disease states. To test this hypothesis, we compared the stride-interval time series of 1) healthy elderly subjects and young controls and of 2) subjects with Huntington's disease and healthy controls. Using detrended fluctuation analysis we computed alpha, a measure of the degree to which one stride interval is correlated with previous and subsequent intervals over different time scales. The scaling exponent alpha was significantly lower in elderly subjects compared with young subjects (elderly: 0.68 +/- 0.14; young: 0.87 +/- 0.15; P < 0.003). The scaling exponent alpha was also smaller in the subjects with Huntington's disease compared with disease-free controls (Huntington's disease: 0.60 +/- 0.24; controls: 0.88 +/-0.17; P < 0.005). Moreover, alpha was linearly related to degree of functional impairment in subjects with Huntington's disease (r = 0.78, P < 0.0005). These findings demonstrate that strike-interval fluctuations are more random (i.e., less correlated) in elderly subjects and in subjects with Huntington's disease. Abnormal alterations in the fractal properties of gait dynamics are apparently associated with changes in central nervous system control.
793 citations
TL;DR: Four weeks of living high-training low improves sea-level running performance in trained runners due to altitude acclimatization and maintenance of sea- level training velocities, most likely accounting for the increase in velocity at VO2 max and MSS.
Abstract: Levine, Benjamin D., and James Stray-Gundersen.“Living high-training low”: effect of moderate-altitude acclimatization with low-altitude training on performance.J. Appl. Physiol. 83(1): 102–112, 19...
695 citations
TL;DR: It is concluded that Wb normally incurred during maximal exercise causes vasoconstriction in locomotor muscles and compromises locomotor muscle perfusion and VO2.
Abstract: Harms, Craig A., Mark A. Babcock, Steven R. McClaran, David F. Pegelow, Glenn A. Nickele, William B. Nelson, and Jerome A. Dempsey.Respiratory muscle work compromises leg blood flow during maximal ...
662 citations
TL;DR: Results add further support to the validity of the Hanai theory, the equation used, and the conclusion that ECW and ICW volume can be predicted by an approach based solely on fundamental principles.
Abstract: De Lorenzo, A., A. Andreoli, J. Matthie, and P. Withers.Predicting body cell mass with bioimpedance by using theoretical methods: a technological review. J. Appl. Physiol. 82(5): 1542–1558, 1997.—T...
649 citations
TL;DR: It is concluded that the passive pharynx is more narrow and collapsible in sleep-apneic patients than in matched controls and that velopharyngeal Pc is the principal correlate of the frequency of nocturnal desaturations.
Abstract: Isono, Shiroh, John E Remmers, Atsuko Tanaka, Yasuhide Sho, Jiro Sato, and Takashi Nishino. Anatomy of pharynx in patients with obstructive sleep apnea and in normal subjects.J. Appl. Physiol. 82(4...
518 citations
TL;DR: It is concluded that long-term creatine supplementation enhances the progress of muscle strength during resistance training in sedentary females.
Abstract: Vandenberghe, K., M. Goris, P. Van Hecke, M. Van Leemputte, L. Vangerven, and P. Hespel. Long-term creatine intake is beneficial to muscle performance during resistance training.J. Appl. Physiol. 8...
444 citations
TL;DR: It is concluded that there are differences in fascicle lengths and pennation angles when the muscle is in a relaxed and isometrically tensed conditions and that the differences are affected by joint angles, at least at the submaximal contraction level.
Abstract: Fukunaga, Tetsuo, Yoshiho Ichinose, Masamitsu Ito, Yasuo Kawakami, and Senshi Fukashiro. Determination of fascicle length and pennation in a contracting human muscle in vivo.J. Appl. Physiol. 82(1)...
444 citations
TL;DR: The altered ratio between glycolytic and oxidative enzyme activities found in skeletal muscle of individuals with NIDDM suggests that a dysregulation between mitochondrial oxidative capacity and capacity for gly colysis is an important component of the expression of insulin resistance.
Abstract: The insulin resistance of skeletal muscle in glucose-tolerant obese individuals is associated with reduced activity of oxidative enzymes and a disproportionate increase in activity of glycolytic enzymes. Because non-insulin-dependent diabetes mellitus (NIDDM) is a disorder characterized by even more severe insulin resistance of skeletal muscle and because many individuals with NIDDM are obese, the present study was undertaken to examine whether decreased oxidative and increased glycolytic enzyme activities are also present in NIDDM. Percutaneous biopsy of vatus lateralis muscle was obtained in eight lean (L) and eight obese (O) nondiabetic subjects and in eight obese NIDDM subjects and was assayed for marker enzymes of the glycolytic [phosphofructokinase, glyceraldehyde phosphate dehydrogenase, hexokinase (HK)] and oxidative pathways [citrate synthase (CS), cytochrome-c oxidase], as well as for a glycogenolytic enzyme (glycogen phosphorylase) and a marker of anaerobic ATP resynthesis (creatine kinase). Insulin sensitivity was measured by using the euglycemic clamp technique. Activity for glycolytic enzymes (phosphofructokinase, glyceraldehye phosphate dehydrogenase, HK) was highest in subjects with subjects with NIDDM, following the order of NIDDM > O > L, whereas maximum velocity for oxidative enzymes (CS, cytochrome-c oxidase) was lowest in subjects with NIDDM. The ratio between glycolytic and oxidative enzyme activities within skeletal muscle correlated negatively with insulin sensitivity. The HK/CS ratio had the strongest correlation (r = -0.60, P < 0.01) with insulin sensitivity. In summary, an imbalance between glycolytic and oxidative enzyme capacities is present in NIDDM subjects and is more severe than in obese or lean glucose-tolerant subjects. The altered ratio between glycolytic and oxidative enzyme activities found in skeletal muscle of individuals with NIDDM suggests that a dysregulation between mitochondrial oxidative capacity and capacity for glycolysis is an important component of the expression of insulin resistance.
442 citations
TL;DR: Theimmune response to heavy exertion is transient, and further research on the mechanisms underlying the immune response to prolonged and intensive endurance exercise is necessary before meaningful clinical applications can be drawn.
Abstract: Nieman, David C. Immune response to heavy exertion. J. Appl. Physiol. 82(5): 1385–1394, 1997.—Epidemiological data suggest that endurance athletes are at increased risk for upper respiratory tract ...
TL;DR: Insight is provided into how k(leg) adjustments can allow similar locomotion mechanics on the variety of terrains encountered by runners in the natural world.
Abstract: Ferris, Daniel P., and Claire T. Farley. Interaction of leg stiffness and surface stiffness during human hopping.J. Appl. Physiol. 82(1): 15–22, 1997.—When mammals run, the overall musculoskeletal ...
TL;DR: The results suggest that NO may be a potential mediator of exercise-induced glucose transport, and chronic treadmill training increased protein expression of both type I and type III NOS in soleus muscle homogenates.
Abstract: Balon, Thomas W., and Jerry L. Nadler. Evidence that nitric oxide increases glucose transport in skeletal muscle.J. Appl. Physiol. 82(1): 359–363, 1997.—Nitric oxide synthase (NOS) is expressed in ...
TL;DR: It is demonstrated that the superimposition of dehydration on hyperthermia during exercise in the heat causes an inability to maintain cardiac output and blood pressure that makes the dehydrated athlete less able to cope withhyperthermia.
Abstract: Gonzalez-Alonso, Jose, Ricardo Mora-Rodriguez, Paul R. Below, and Edward F. Coyle.Dehydration markedly impairs cardiovascular function in hyperthermic endurance athletes during exercise. J. Appl. ...
TL;DR: It is suggested that the strength loss is also due to factors resulting in decreased neural input to muscle and/or reduced specific tension of muscle, as evidenced by decreased torque/EMG ratio.
Abstract: Berg, H. E., L. Larsson, and P. A. Tesch. Lower limb skeletal muscle function after 6 wk of bed rest. J. Appl. Physiol. 82(1): 182–188, 1997.—Force, electromyographic (EMG) activity, muscle mass, a...
TL;DR: The data indicate that carbohydrate ingestion attenuates cytokine levels in the inflammatory cascade in response to heavy exertion.
Abstract: Nehlsen-Cannarella, S. L., O. R. Fagoaga, D. C. Nieman, D. A. Henson, D. E. Butterworth, R. L. Schmitt, E. M. Bailey, B. J. Warren, A. Utter, and J. M. Davis. Carbohydrate and the cytokine response...
TL;DR: From QB to 0% Wmax there is a switch in respiratory muscle control, with immediate recruitment of rib cage and abdominal muscles, and a simple mechanism that increases drive equally to all three muscle groups allows the diaphragm to contract quasi-isotonically and act as a flow generator, while rib cage
Abstract: Aliverti, A., S. J. Cala, R. Duranti, G. Ferrigno, C. M. Kenyon, A. Pedotti, G. Scano, P. Sliwinski, Peter T. Macklem, and S. Yan. Human respiratory muscle actions and control during exercise.J. Ap...
TL;DR: It is suggested that PVI tests may be used to extract information not only on intracranial compliance and CSF circulation, but also on the status of mechanisms controlling CBF, and the generation of plateau waves and the effect of acute arterial hypotension on ICP.
Abstract: A simple mathematical model of intracranial pressure (ICP) dynamics oriented to clinical practice is presented. It includes the hemodynamics of the arterial-arteriolar cerebrovascular bed, cerebrospinal fluid (CSF) production and reabsorption processes, the nonlinear pressure-volume relationship of the craniospinal compartment, and a Starling resistor mechanism for the cerebral veins. Moreover, arterioles are controlled by cerebral autoregulation mechanisms, which are simulated by means of a time constant and a sigmoidal static characteristic. The model is used to simulate interactions between ICP, cerebral blood volume, and autoregulation. Three different related phenomena are analyzed: the generation of plateau waves, the effect of acute arterial hypotension on ICP, and the role of cerebral hemodynamics during pressure-volume index (PVI) tests. Simulation results suggest the following: 1) ICP dynamics may become unstable in patients with elevated CSF outflow resistance and decreased intracranial compliance, provided cerebral autoregulation is efficient. Instability manifests itself with the occurrence of self-sustained plateau waves. 2) Moderate acute arterial hypotension may have completely different effects on ICP, depending on the value of model parameters. If physiological compensatory mechanisms (CSF circulation and intracranial storage capacity) are efficient, acute hypotension has only negligible effects on ICP and cerebral blood flow (CBF). If these compensatory mechanisms are poor, even modest hypotension may induce a large transient increase in ICP and a significant transient reduction in CBF, with risks of secondary brain damage. 3) The ICP response to a bolus injection (PVI test) is sharply affected, via cerebral blood volume changes, by cerebral hemodynamics and autoregulation. We suggest that PVI tests may be used to extract information not only on intracranial compliance and CSF circulation, but also on the status of mechanisms controlling CBF.
TL;DR: It is concluded that body composition estimates from DEXA are accurate compared with those from a four-component model in young adults who vary in gender, race, athletic status, body size, musculoskeletal development, and body fatness.
Abstract: Prior, Barry M., Kirk J. Cureton, Christopher M. Modlesky, Ellen M. Evans, Mark A. Sloniger, Michael Saunders, and Richard D. Lewis. In vivo validation of whole body composition estimates from dual...
TL;DR: The importance of heat shock proteins (HSPs) in thermotolerance and differences in their accumulation in organisms adapted to the heat suggest a role for HSPs in acclimatization as well.
Abstract: Moseley, Pope L. Heat shock proteins and heat adaptation of the whole organism. J. Appl. Physiol. 83(5): 1413–1417, 1997.—Adaptation to heat may occur through acclimatization or thermotolerance; ho...
TL;DR: A finite-element analysis of a two-layer composite model for an airway is used to investigate the factors that determine the mucosal folding pattern and how it is altered as a result of changes in the thickness or stiffness of the different layers that comprise the airway wall.
Abstract: Wiggs, Barry R., Constantine A. Hrousis, Jeffrey M. Drazen, and Roger D. Kamm. On the mechanism of mucosal folding in normal and asthmatic airways. J. Appl. Physiol. 83(6): 1814–1821, 1997.—Previou...
TL;DR: The inherent problems of the Ultrasound Doppler technique have been addressed, and the accuracy was improved by storing the velocity tracings continuously and calculating the flow in relation to the muscle contraction-relaxation phases.
Abstract: Radegran, G. Ultrasound Doppler estimates of femoral artery blood flow during dynamic knee extensor exercise in humans. J. Appl. Physiol.83(4): 1383–1388, 1997.—Ultrasound Doppler has been used to ...
TL;DR: Faster on-transient responses in exercise above, but not below, VT with hyperoxia and, to a lesser degree, after prior high-intensity exercise above VT support the theory of an O2 transport limitation at the onset of exercise for workloads >VT.
Abstract: MacDonald, Maureen, Preben K. Pedersen, and Richard L. Hughson. Acceleration ofV˙o 2 kinetics in heavy submaximal exercise by hyperoxia and prior high-intensity exercise.J. Appl. Physiol. 83(4): 13...
TL;DR: The hypothesis that, in contrast to the prevailing view, the rate of decline in maximal aerobic capacity with age is greater, not smaller, in endurance-trained vs. sedentary women is supported.
Abstract: Fitzgerald, Margaret D., Hirofumi Tanaka, Zung V. Tran, and Douglas R. Seals. Age-related declines in maximal aerobic capacity in regularly exercising vs. sedentary women: a meta-analysis.J. Appl. ...
TL;DR: It is concluded that there are no meaningful acute or chronic effects of exercise, independent of the amount of body fat, on leptin levels in humans.
Abstract: Perusse, Louis, Gregory Collier, Jacques Gagnon, Arthur S. Leon, D. C. Rao, James S. Skinner, Jack H. Wilmore, Andre Nadeau, Paul Z. Zimmet, and Claude Bouchard. Acute and chronic effects of exerci...
TL;DR: The results of this study suggest that the inherent characteristics of skeletal muscle fibers per se and of skeletal Muscle as a whole are altered in the direction of disuse in MS and suggest that changes in skeletal muscle in MS may significantly affect function.
Abstract: Kent-Braun, J. A., A. V. Ng, M. Castro, M. W. Weiner, D. Gelinas, G. A. Dudley, and R. G. Miller. Strength, skeletal muscle composition and enzyme activity in multiple sclerosis.J. Appl. Physiol. 8...
TL;DR: CO and stroke volume can be estimated during progressive work rate exercise testing from measured Vo2 (in normal subjects and patients with congestive heart failure), and the resultant linear regression equation provides a good estimate of C(a-vDo2).
Abstract: Stringer, William W., James E. Hansen, and K. Wasserman.Cardiac output estimated noninvasively from oxygen uptake during exercise. J. Appl. Physiol. 82(3): 908–912, 1997.—Because gas-exchange measu...
TL;DR: Evaluated the effect of running intensity on small intestinal permeability by using the lactulose and rhamnose differential urinary excretion test and found increases did not result in a higher prevalence of gastrointestinal symptoms, and urinary recovery of sucrose did not reflect increased gastric permeability.
Abstract: Enhanced intestinal permeability has been associated with gastrointestinal disorders in long-distance runners. The primary purpose of this study was to evaluate the effect of running intensity on small intestinal permeability by using the lactulose and rhamnose differential urinary excretion test. Secondary purposes included assessing the relationship between small intestinal permeability and gastrointestinal symptoms and evaluating gastric damage by using sucrose as a probe. Six healthy volunteers [5 men, 1 woman; age = 30 +/- 2 yr; peak O2 uptake (VO2peak) = 57.7 +/- 2.1 ml.kg-1.min-1] rested or performed treadmill exercise at 40, 60, or 80% VO2peak for 60 min in a moderate environment (22 degrees C, 50% relative humidity). At 30 min into rest or exercise, the permeability test solution (5 g sucrose, 5 g lactulose, 2 g rhamnose in 50 ml water, approximately 800 mosM) was ingested. Urinary excretion rates (6 h) of the lactulose-to-rhamnose ratio were used to assess small intestinal permeability, and concentrations of each probe were determined by using high-performance liquid chromatography. Running at 80% VO2peak increased (P < 0.05) small intestinal permeability compared with rest, 40, and 60% VO2peak with mean values expressed as percent recovery of ingested dose of 0.107 +/- 0.021 (SE), 0.048 +/- 0.009, 0.056 +/- 0.005, and 0.064 +/- 0.010%, respectively. Increases in small intestinal permeability did not result in a higher prevalence of gastrointestinal symptoms, and urinary recovery of sucrose did not reflect increased gastric permeability. The significance and mechanisms involved in increased small intestinal permeability after high-intensity running merit further investigation.
TL;DR: It is concluded that physical fitness and formation of NO at rest are positively linked to each other and a single session of exercise elicits an acute elevation of NO formation.
Abstract: Jungersten, Lennart, Anneli Ambring, Bjorn Wall, andAke Wennmalm. Both physical fitness and acute exercise regulate nitric oxide formation in healthy humans. J. Appl. Physiol. 82(3): 760–764, 1997....
TL;DR: A follow-up of aerobic power and body composition was performed by Pollock, Michael L., Michael L. Mengelkoch, James E. Graves, David T. Lowenthal, Marian C. Limacher, Carl Foster, and Jack H. Wilmore as discussed by the authors.
Abstract: Pollock, Michael L., Larry J. Mengelkoch, James E. Graves, David T. Lowenthal, Marian C. Limacher, Carl Foster, and Jack H. Wilmore. Twenty-year follow-up of aerobic power and body composition of o...