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S F Siconolfi

Publications and source records attributed to S F Siconolfi.

15 recordsLinked to original sources
PubMed1995

Graded exercise testing for spaceflight.

We developed and validated a graded exercise protocol suitable for operational use on space station. The new treadmill protocol has three level-grade stages (3-min each) at 70, 80, and 90% of estimated VO2peak. The protocol maintains the third stage speed while grade increases each minute to produce work rates equivalent to 100, 107, and 115% of the estimated VO2peak. We compared the new protocol's peak and submaximal responses to those observed during a NASA graded exercise test. All mean protocol differences, including peak work rate (-1.8%), VO2peak (-6.4%), HRpeak (-2.4%), and VEpeak (-9.7%), were not significantly different from the expected measurement errors. We observed similar results for indices (the oxygen uptake at a HR of 150 and the HR's at 70, 80, and 90% of VO2peak) of the submaximal HR-VO2 relationship. The new protocol is an acceptable graded exercise test for periodic operational fitness tests.

Adult↗
PubMed1994

Comparing the effects of two in-flight aerobic exercise protocols on standing heart rates and VO(2peak) before and after space flight.

The effects of regular aerobic exercise on orthostatic tolerance have been the subject of a long-standing controversy that will influence the use of exercise during space flight. To examine these effects, astronauts performed continuous (CE) aerobic exercise (n = 8), interval (IE) aerobic exercise (n = 4), or no (NE) exercise (n = 5) during flights of 7 to 11 days. Heart rate (HR) responses to an orthostatic challenge (stand test) were measured 10 days before flight and on landing day. VO(2peak) (graded treadmill exercise) was measured 7 to 21 days before and 2 days after flight. No significant differences across the groups were observed in standing HRs before or after flight. However, the within-group mean HRs significantly increased in the NE (71-89 beats/min) and CE (60-85 beats/min) groups after space flight. The HRs for the IE group did not significantly increase (75-86 beats/min) after space flight. VO(2peak) decreased (P < .05) in the NE (-9.5%) group, but did not change in the CE (-2.4%) and IE (1%) groups. The relationship (r = 0.237) between the delta HR and delta VO(2peak) was not significant. These preliminary results indicate that: (1) continuous exercise does not affect the orthostatic HR response after space flight; (2) interval exercise may minimize an increase in the postflight orthostatic HR; and (3) both exercise protocols can maintain VO(2peak).

Adult↗
PubMed1994

Physical performance is maintained in women consuming only foods used on the U.S. Space Shuttle.

In-flight reductions in caloric intake, body weight, lean body mass (LBM), aerobic capacity, and other measures of physical performance have been consistent findings in the U.S. and Russian space programs. The diet provided for astronauts in space has been suggested as a possible contributor to these changes because food selection, preparation, and storage facilities are limited on spacecraft. In this ground-based study, consuming only foods used on the Space Shuttle for 28 d did not affect aerobic capacity, LBM, or measures of muscle strength or endurance in 12 healthy women (ages 28-47 years). However, normal consumption patterns were affected by restriction to the Space Shuttle diet, namely a proportional increase in carbohydrate consumed, with compensatory decreases in protein and fat. These results suggest that physical performance and LBM can be maintained under normal gravity conditions in active women who consume a Space Shuttle food-system diet for 28 d.

Adult↗
PubMed1992

Metabolic and performance responses to uphill and downhill running in distance runners.

Distance running performance is slower on hilly race courses than flat courses even when the start and finish are at the same elevation, resulting in equal amounts of uphill and downhill running. The physiological mechanism limiting performance on these courses is not known. We examined the effects of uphills and downhills with 11 trained male distance runners running three 30 min self-paced competitive races on a treadmill. Race courses consisted of five, 6 min stages. Percent grades were: course A (0, 0, 0, 0, 0), course B (0, +5, 0, -5, 0) and course C (0, -5, 0, +5, 0). Pace, oxygen consumption (VO2), heart rate (HR), blood lactate (LA), and rating of perceived exertion (RPE) did not change significantly (P greater than 0.05) over stages on the control course A. Pace changed inversely with percent grade on courses B and C. The increase in downhill running pace was inadequate to maintain a level VO2 during the race. LA increased on the uphill stages even though running pace decreased. The running paces for courses B and C were slower (P less than 0.05) than course A by 2.8% and 2.4%, respectively. Runners do not maintain constant energy expenditure when racing on hilly courses. Lactate accumulated on uphill stages even though pace decreased. Running pace increased on downhills but not enough to maintain a constant VO2.

Adult↗
PubMed1991

A comparison between computer-controlled and set work rate exercise based on target heart rate.

Good exercise prescriptions provide work rates (WRs) that maintain heart rates (HR) in a target zone and at a percent of maximum metabolic equivalent (%METmax). HR and MET were evaluated from computer-controlled and set WR (constant speed) sessions (20 min at 65% METmax). Computer-controlled WR used a control algorithm to adjust speed and grade to maintain the target HR. The set WR (mean +/- S.D.) HR (139 +/- 8 bpm) was lower (p less than 0.05) than the target (147 +/- 3 bpm) and computer-controlled HRs (153 +/- 5 bpm). The set WR MET (8.6 +/- 2.2) was not different than the target (8.6 +/- 2.2), but both were lower than computer-controlled exercise (9.7 +/- 2.2). Computer-control time in target HR zone (16 +/- 5 min) was significantly (p less than 0.004) greater than set WR exercise (6 +/- 5 min). Computer-controlled WR was significantly better in maintaining target HR and the MET values were not physiologically different than target WRs.

Adult↗
PubMed1990

Mechanical efficiency during cycling in prepubertal and adult males.

Previous studies have indicated that values for mechanical efficiency during cycle exercise in prepubertal subjects are similar to those in adults. Few studies have directly compared these groups, however, and earlier reports did not consider the importance of assessing efficiency at similar relative exercise intensities. Nineteen prepubertal boys and 21 college men underwent cycle exercise testing for determination of delta efficiency (the energy required to increase workload), related to both absolute work load and relative work intensity (percent VO2max). No significant differences in either of these measures were observed between the two groups. Mean delta efficiency between workloads of similar relative intensity was 23.2% for the prepubertal subjects and 22.5% for the adults (p greater than .05). Between equal absolute workloads the values were 23.2 and 26.5%, respectively (p greater than .05). These findings support earlier contentions that the efficiency of muscular contraction during exercise is comparable in pre- and post-pubertal subjects.

Adult↗
PubMed1987

Plasma beta-endorphin levels in silent myocardial ischemia induced by exercise.

Although silent myocardial ischemia is a well recognized phenomenon, the reasons for the lack of symptoms in patients with coronary artery disease (CAD) is unclear. Because the endogenous opioid beta-endorphin has been related to pain modulation, plasma beta-endorphin levels were studied before, during and after exercise-induced ischemia in symptomatic and asymptomatic men. Because beta-endorphin responses have been closely linked to adrenocorticotropic hormone (ACTH) and cortisol responses, these hormones also were measured. Nine symptomatic and 12 asymptomatic patients with a high probability (at least 95%) of CAD and 8 apparently healthy men completed a Bruce protocol treadmill test. Blood samples were drawn before, during and 10 minutes after exercise. During exercise the measured hormones showed no significant increases from basal levels. However, plasma beta-endorphin, ACTH and cortisol levels were significantly elevated (p less than or equal to 0.01) 10 minutes after exercise in all 3 groups. There was no significant difference in plasma beta-endorphin levels during or after exercise between the symptomatic and asymptomatic patients with CAD. Thus, differences in circulating levels of beta-endorphin, ACTH and cortisol are not associated with the presence or absence of pain during exercise-induced myocardial ischemia.

Adrenocorticotropic Hormone↗
PubMed1987

'Athlete's heart' in prepubertal children.

Bradycardia, cardiomegaly, heart murmurs, and ECG changes are typically observed in adult endurance athletes, but frequency of such changes among children involved in sports training is unclear. Pediatricians need to be aware of whether these features of the "athlete's heart" occur in their patients, because such features may mimic those of cardiac disease. Fourteen prepubertal competitive male swimmers were evaluated by physical examination, ECG and echocardiogram, and findings were compared to those of a group of active but nontrained control boys. Lower resting heart rates and echocardiographic manifestations of chronic left ventricular volume overload were observed among the swimmers. These changes were not manifest on physical examination, however, and no significant ECG alterations were identified among the athletes. These findings indicate that, although features of the athlete's heart are present in children involved in endurance training, seldom will these findings simulate heart disease or be apparent on routine clinical examination.

Adaptation, Physiological↗
PubMed1985

A simple, valid step test for estimating maximal oxygen uptake in epidemiologic studies.

The authors' modification of the Astrand-Rhyming Cycle Ergometer Test is of short duration, has low initial and peak work rates and was in an earlier study applied for population fitness testing (N = 587) at a survey center after other cardiovascular risk factor measures were obtained in the home. To add fitness testing in the home, the authors have designed a safe, brief 10 inch (25.4 cm) high step test for estimating maximal oxygen uptake (VO2max). Measured maximal oxygen uptake for step tests has been shown to be approximately 10% higher than that reported for cycle tests. All test instructions and stepping rates were included on a cassette tape; heart rates were monitored by a digital tachograph during the last 30 seconds of stepping. Maximal oxygen uptake was measured directly on a bicycle, estimated by the step test, and measured by the authors' bike test in 48 men and women aged 19-70 years who took part in a community fitness program in Pawtucket, Rhode Island in January-February 1983. No significant differences in maximal oxygen uptake were found between the bicycle protocols. The step test estimate of maximal oxygen uptake (VO2max) was significantly higher (12%) than directly measured VO2max, reflecting the expected difference between stepping and cycling. The correlation between direct and both estimates was 0.92. The cross-validation correlation between the estimates was 0.98. The authors' protocol provides accurate estimates of maximal oxygen uptake and is safe and suitable for in-the-home assessment of fitness of people aged 19-70 years for epidemiologic studies.

Adult↗
PubMed1985

Self-reported physical activity compared with maximal oxygen uptake.

Maximal oxygen uptake has been used as a measure of physical fitness. This measure increases by approximately 25% when sedentary individuals become more physically active. Oxygen uptake measurement in the laboratory or estimation in fieldwork is complex and costly with finite risk. For the present study, 36 men and 32 women completed the Paffenbarger Physical Activity Index Questionnaire, including a sweat-inducing physical activity frequency question, and had measurement of oxygen uptake during pedal ergometry. Using maximal oxygen uptake as the measure of fitness, the authors found that the Paffenbarger Physical Activity Index, although more detailed, may be less valid than the simpler sweat induction frequency question for estimating fitness. The correlations observed between the sweat question and oxygen uptake were 0.54 for males, 0.26 for females, and 0.46 for the total group. The correlations between the Physical Activity Index and oxygen uptake were 0.26 for males, 0.08 for females, and 0.29 for the total group. The regression relationship (oxygen uptake = 1.92 X (sweat days) + 23.76; standard error of estimate = 8.63 ml/kg/min) is significant for sweat versus oxygen uptake. While the confidence interval limits the practical ability to predict individual values, low cost, absence of risk, and population validity suggest that fitness can be assessed rapidly and simply for epidemiologic studies with a simple "sweat" question.

Adult↗
PubMed1985

Physical fitness and blood pressure: the role of age.

Most epidemiologic studies have shown an inverse relationship between resting blood pressure and usual levels of physical fitness or activity. The inference is that fitness lowers blood pressure. However, maximum oxygen uptake (VO2max--a widely accepted measure of fitness) and blood pressure are both correlated with age; young people usually have lower pressures and higher VO2max (ml X kg-1 X min-1). Systolic and diastolic pressures were measured and maximal oxygen uptake was estimated in 184 men and 227 women aged 18-65 years who were randomly selected as part of a cardiovascular risk factor survey conducted in two New England cities between April 1981 and March 1982. Initially, both measures of blood pressure were strongly and inversely correlated with estimated maximal oxygen uptake. However, when the effects of age were partialed out, the strength of the correlations decreased sharply for both males and females. The proportion of the variance in systolic pressure explained by maximal oxygen uptake decreased from 9.6 to 0.8% for males and 21.2 to 2.3% for females. Similar decreases were demonstrated for diastolic pressure in males (14.4 to 2.9%) and females (20.3 to 2.3%). These data indicate that the frequently observed relationship between fitness and blood pressure is strongly influenced by age. Future research to specifically examine the effects of physical activity and of physical fitness on blood pressure is needed.

Adolescent↗
PubMed1985

Validity of "generalized" equations for body composition analysis in male athletes.

Equations by Durnin and Womersley [(D-W), Br. J. Nutr. 32:77, 1974], Jackson and Pollock [(J-P), Br. J. Nutr. 40:497, 1978], and Lohman [(L), Human Biol., 53:181, 1981] for estimating body density (BD) purportedly overcome the problem of specificity by accounting for age and/or the curvilinear relationship between skinfolds (SF) and BD. Their equations were validated on 265 male athletes against percent fat measured by underwater weighing [(UWW); mean +/- SD = 9.2 +/- 4.4%]. Equations by Sloan [(S), J. Appl. Physiol. 23:311, 1967], Katch and McArdle [(K-M), Human. Biol. 45:445, 1973], and Forsyth and Sinning [(F-S), Med. Sci. Sports 5:174, 1973] were included as "linear regression models" to compare to the curvilinear models of J-P, D-W, and L. Differences between UWW and estimated mean values ranged from -1.1 to +5.9%; correlations ranged from 0.58 to 0.85; SEE ranged from +/- 2.41 to +/- 3.61% and total error (E) ranged from 2.38 to 6.97%. The seven D-W equations overestimated mean percent fat by from 3.9 to 5.9%. The K-M, S, and L equations overestimated by 1.3, 0.5, and 1.7%, respectively. The F-S equations overestimated by 2.4 to 3.8%. Of the 21 equations evaluated, only 3 by J-P gave estimates not significantly different from UWW percent fat. Regression analyses of the relationship between UWW (y) and estimated (x) percent fat values from those equations were: y = 1.037x - 0.08 +/- 2.38, E = 2.38, r = 0.84; 0.869x + 1.36 +/- 2.45, E = 2.51, r = 0.83; 1.107x - 1.14 +/- 2.51, E = 2.53, r = 0.82.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1984

Circulatory effects of mental stress during exercise in coronary artery disease patients.

We examined the effects of mental stress during steady-state exercise on heart rate, blood pressure, pressure-rate product, and oxygen uptake in 10 coronary artery disease patients. Subjects walked at three mph with grade increases of 4% every two minutes until the target heart rate (60% peak heart rate from a previous symptom-limited exercise test) was reached. A computerized Stroop-Color-Word Test (mental stress) was added one minute after the subject reached steady-state exercise and lasted 11 +/- 4 minutes. When mental stress was added to steady-state exercise it significantly (p less than 0.01) increased the heart rate (101 +/- 15 to 108 +/- 19 beats per min), systolic (154 +/- 26 to 170 +/- 26 mmHg) and diastolic (86 +/- 10 to 92 +/- 13 mmHg) blood pressure, and pressure-rate product (158 +/- 42 to 179 +/- 48 x 10(-2)). This increase in the mean response during exercise and mental stress was not observed for oxygen uptake (17 +/- 6 to 18 +/- 5 ml/kg/min). The circulatory changes probably reflect increased sympathetic activity with both centrally mediated cardioacceleratory (and probably cardiac output) and vasoconstrictor effects during the combination of mental stress and steady-state exercise. The altered hemodynamics without concomitant changes in oxygen uptake has major implications concerning the safety of competitive exercise for people with coronary artery disease.

Adult↗
PubMed1982

Assessing VO2max in epidemiologic studies: modification of the Astrand-Rhyming test.

Direct measurement of maximum oxygen uptake (VO2max) is the standard index of cardiorespiratory fitness, but is practical only in a laboratory setting. Current cycle ergometer tests to estimate VO2max are difficult for inactive adults because most of these tests are lengthy and require a high initial exercise rate. We modified an existing test, the Astrand-Rhyming test, to avoid these problems. Maximum oxygen uptake was measured directly and estimated by means of our protocol in a test group of 50 men and women, ten for each decade between 20 and 70 yr, to develop multiple regression equations to correct for variations due to age. Equations for each sex were computed with directly measured VO2max as the dependent variable and with the estimated VO2max and age as independent variables. The validity of these equations was tested by deriving data from an additional 63 subjects (validity group). No significant differences were found between the directly measured VO2max and the VO2max estimated by our protocol and equations. For each group, the mean difference between the two values was less than 120 ml X min-1. Correlations between the measured and estimated VO2max ranged from 0.92-0.93 for the age groups. Our modification of the Astrand-Rhyming protocol accurately estimates VO2max and is safe and suitable for assessing cardiovascular fitness in epidemiologic studies of people between the ages of 20-70 yr.

Adult↗