Time course and mechanisms of adaptations in cardiorespiratory fitness with endurance training in older and young men

The time-course and mechanisms of adaptation of cardiorespiratory fitness were examined in 8 older (O) (68 ± 7 yr old) and 8 young (Y) (23 ± 5 yr old) men pretraining and at 3, 6, 9, and 12 wk of training. Training was performed on a cycle ergometer three times per week for 45 min at ∼70% of maximal oxygen uptake (V̇o2 max). V̇o2 max increased within 3 wk with further increases observed posttraining in both O (+31%) and Y (+18%), ( P < 0.05). Maximal cardiac output (Q̇max, open-circuit acetylene) and stroke volume were higher in O and Y after 3 wk with further increases after 9 wk of training ( P < 0.05). Maximal arterial-venous oxygen difference (a-vO2diff) was higher at weeks 3 and 6 and posttraining compared with pretraining in O and Y ( P < 0.05). In O, ∼69% of the increase in V̇o2 max from pre- to posttraining was explained by an increased Q̇max with the remaining ∼31% explained by a widened a-vO2diff. This proportion of Q̇ and a-vO2diff contributions to the increase in V̇o2 max was consistent throughout testing in O. In Y, 56% of the pre- to posttraining increase in V̇o2 max was attributed to a greater Q̇max and 44% to a widened a-vO2diff. Early adaptations (first 3 wk) mainly relied on a widened maximal a-vO2diff (∼66%) whereas further increases in V̇o2 max were exclusively explained by a greater Q̇max. In conclusion, with short-term training O and Y significantly increased their V̇o2 max; however, the proportion of V̇o2 max increase explained by Q̇max and maximal a-vO2diff throughout training showed a different pattern by age group.

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Confinement, partial sleep deprivation and defined physical activity–influence on cardiorespiratory regulation and capacity

European Journal of Applied Physiology ◽

10.1007/s00421-021-04719-z ◽

2021 ◽

Author(s):

Jessica Koschate ◽

Uwe Drescher ◽

Uwe Hoffmann

Keyword(s):

Physical Activity ◽

Cardiorespiratory Fitness ◽

Space Mission ◽

Cycle Ergometer ◽

Work Rate ◽

Binary Sequences ◽

Kinetics Parameters ◽

Slow Heart Rate ◽

Partial Sleep Deprivation ◽

Sleep Schedule

Abstract Introduction Adequate cardiorespiratory fitness is of utmost importance during spaceflight and should be assessable via moderate work rate intensities, e.g., using kinetics parameters. The combination of restricted sleep, and defined physical exercise during a 45-day simulated space mission is expected to slow heart rate (HR) kinetics without changes in oxygen uptake ($${\dot{\text{V}}\text{O}}_{{2}}$$ V ˙ O 2 ) kinetics. Methods Overall, 14 crew members (9 males, 5 females, 37 ± 7 yrs, 23.4 ± 3.5 kg m−2) simulated a 45-d-mission to an asteroid. During the mission, the sleep schedule included 5 nights of 5 h and 2 nights of 8 h sleep. The crew members were tested on a cycle ergometer, using pseudo-random binary sequences, changing between 30 and 80 W on day 8 before (MD-8), day 22 (MD22) and 42 (MD42) after the beginning and day 4 (MD + 4) following the end of the mission. Kinetics information was assessed using the maxima of cross-correlation functions (CCFmax). Higher CCFmax indicates faster responses. Results CCFmax(HR) was significantly (p = 0.008) slower at MD-8 (0.30 ± 0.06) compared with MD22 (0.36 ± 0.06), MD42 (0.38 ± 0.06) and MD + 4 (0.35 ± 0.06). Mean HR values during the different work rate steps were higher at MD-8 and MD + 4 compared to MD22 and MD42 (p < 0.001). Discussion The physical training during the mission accelerated HR kinetics, but had no impact on mean HR values post mission. Thus, HR kinetics seem to be sensitive to changes in cardiorespiratory fitness and may be a valuable parameter to monitor fitness. Kinetics and capacities adapt independently in response to confinement in combination with defined physical activity and sleep.

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Physical Activity, Sedentary Behavior, and Cardiorespiratory Fitness in Hazardous and Non-Hazardous Alcohol Consumers

American Journal of Health Promotion ◽

10.1177/0890117120985830 ◽

2021 ◽

pp. 089011712098583

Author(s):

Mats Hallgren ◽

Davy Vancampfort ◽

Thi-Thuy-Dung Nguyen ◽

Elin Ekblom-Bak ◽

Peter Wallin ◽

...

Keyword(s):

Physical Activity ◽

Sedentary Behavior ◽

Cardiorespiratory Fitness ◽

Leisure Time ◽

Health Assessment ◽

Cross Sectional Study ◽

Cycle Ergometer ◽

Cross Sectional ◽

Physically Active ◽

Alcohol Abstainers

Purpose: To describe physical activity habits, sedentary behavior, and cardiorespiratory fitness levels among alcohol abstainers, hazardous and non-hazardous drinkers. Design: Cross-sectional study with data collected between 2017-19. Setting: Sweden. Subjects: Adults aged 18-65 years (n = 47,559; 59.4% male). Measures: During a routine health assessment, participants answered validated single-item questions regarding: habitual physical activity, structured exercise, and the percentage of time spent sedentary during leisure-time (past 30 days), and completed a 6-minute cycle ergometer test (V02max) to determine cardiorespiratory fitness (CRF). Participants were categorized as alcohol abstainers, non-hazardous drinkers or hazardous drinkers (low/high) based on the Alcohol Use Disorders Identification Test (AUDIT-C) cut-points for men and women. Analysis: Logistic regression models stratified by sex and age. Results: Compared to non-hazardous drinkers, the heaviest drinkers were less physically active (males: OR = 1.38, CI = 1.13-1.67, p = .001; females: OR = 1.41, CI = 1.01-1.97, p = .040) and more sedentary during leisure time (males: OR = 1.94, CI = 1.62-2.32, p = .000; females: OR = 1.62, CI = 1.21-2.16, p = .001). Apart from young females, the heaviest drinkers also did less structured exercise than non-hazardous drinkers (males: OR = 1.22, CI = 1.15-1.51, p = .000; females: OR = 1.43, CI = 1.15-1.78, p = .001). The strongest associations were seen among adults aged 40-65 years (shown here). High-hazardous drinking was associated with low CRF among older males only (OR = 1.19, CI = 1.00-1.41). Conclusion: Middle-aged adults with AUDIT-C scores of ≥6 (women) and ≥7 (men) were less physically active and more sedentary during leisure time and may be appropriate targets for physical activity interventions.

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MECHANISMS OF ADAPTATION OF THE LEFT VENTRICLE TO MUSCULAR EXERCISE

PEDIATRICS ◽

10.1542/peds.32.4.660 ◽

1963 ◽

Vol 32 (4) ◽

pp. 660-670

Author(s):

Jere H. Mitchell

Keyword(s):

Cardiac Output ◽

Left Ventricle ◽

Stroke Volume ◽

Pulse Rate ◽

Individual Factors ◽

Normal Male ◽

Oxygen Intake ◽

Mechanisms Of Adaptation ◽

Male Subjects ◽

Oxygen Difference

THE mechanisms of adaptation of the left ventricle to the demands of muscular exercise have intrigued cardiovascular physiologists for many years. Although highly complex, these adaptive mechanisms are more and more susceptible to analysis and quantification. In this presentation I will attempt to identify some of the individual factors which appear to be important in the response of the left ventricle to exercise, beginning with data obtained from experiments on conscious normal male subjects and proceeding to experiments performed on dog preparations in which individual factors were controlled and analyzed. The changes in oxygen intake, cardiac output, estimated arteriovenous oxygen difference, pulse rate and estimated mean stroke volume were determined in 15 normal male subjects during rest in the standing position and during treadmill exercise at the maximal oxygen intake level. Oxygen intake was obtained from the volume and composition of expired air, cardiac output by the dye dilution technique, and pulse rate from the electrocardiogram. Estimated arteriovenous oxygen difference was obtained by dividing the oxygen intake by the cardiac output (Fick principle) and estimated mean stroke volume by dividing the cardiac output by the heart rate. The data are shown in Figure 1. Oxygen intake increased from a mean value of 0.34 at rest to a maximal value of 3.22 L./min. The corresponding mean values for cardiac output were 5.4 and 23.4 L./min. and for arteriovenous oxygen difference were 6.5 and 14.3 ml./100 ml. Thus, as oxygen intake increased 9.5 times, the cardiac output increased 4.3 times and the arterio venous oxygen difference 2.2 times.

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Sensation of dyspnea during hypercapnia, exercise, and voluntary hyperventilation

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.5.2100 ◽

1990 ◽

Vol 68 (5) ◽

pp. 2100-2106 ◽

Cited By ~ 38

Author(s):

T. Chonan ◽

M. B. Mulholland ◽

J. Leitner ◽

M. D. Altose ◽

N. S. Cherniack

Keyword(s):

Visual Analog Scale ◽

Line Intensity ◽

Time Course ◽

Normal Subjects ◽

Cycle Ergometer ◽

Base Line ◽

Analog Scale ◽

Voluntary Hyperventilation ◽

The Difference ◽

End Tidal

To determine whether the intensity of dyspnea at a given level of respiratory motor output depends on the nature of the stimulus to ventilation, we compared the sensation of difficulty in breathing during progressive hypercapnia (HC) induced by rebreathing, during incremental exercise (E) on a cycle ergometer, and during isocapnic voluntary hyperventilation (IVH) in 16 normal subjects. The sensation of difficulty in breathing was rated at 30-s intervals by use of a visual analog scale. There were no differences in the level of ventilation or the base-line intensity of dyspnea before any of the interventions. The intensity of dyspnea grew linearly with increases in ventilation during HC [r = 0.98 +/- 0.02 (SD)], E (0.95 +/- 0.03), and IVH (0.95 +/- 0.06). The change in intensity of dyspnea produced by a given change in ventilation was significantly greater during HC [0.27 +/- 0.04 (SE)] than during E (0.12 +/- 0.02, P less than 0.01) and during HC (0.30 +/- 0.04) than during IVH (0.16 +/- 0.03, P less than 0.01). The difference in intensity of dyspnea between HC and E or HC and IVH increased as the difference in end-tidal PCO2 widened, even though the time course of the increase in ventilation was similar. No significant differences were measured in the intensity of dyspnea that occurred with changes in ventilation between E and IVH. These results indicate that under nearisocapnic conditions the sensation of dyspnea produced by a given level of ventilation seems not to depend on the method used to produce that level of ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effect of age on body composition and resting metabolic rate

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.259.2.e233 ◽

1990 ◽

Vol 259 (2) ◽

pp. E233-E238 ◽

Cited By ~ 20

Author(s):

N. K. Fukagawa ◽

L. G. Bandini ◽

J. B. Young

Keyword(s):

Body Composition ◽

Metabolic Rate ◽

Isotope Dilution ◽

Resting Metabolic Rate ◽

Bioelectrical Impedance ◽

Impedance Analysis ◽

Open Circuit ◽

Fat Free Mass ◽

The Difference ◽

Old Men

The relationship between fat-free mass (FFM) and resting metabolic rate (RMR) was compared in young men (n = 24; age 18-33 yr), old men (n = 24; 69-89 yr), and old women (n = 20; 67-75 yr). Body composition was assessed using anthropometry, bioelectrical impedance analysis (BIA), and isotope dilution with 18O-labeled water. RMR was measured at least twice using an open-circuit indirect calorimetry system with a ventilated hood. The results indicate that the different methods for assessing body composition vary substantially and should not be used interchangeably. Anthropometry was not adequate to assess group differences in body fatness, although skinfold measures may be appropriate for within-group comparisons. BIA correlated well with the isotope-dilution technique and may be a useful measure of FFM. Finally, RMR was lower in the old men than the young (1.04 +/- 0.02 vs. 1.24 +/- 0.03 kcal/min, P less than 0.001) and remained lower even when adjusted for FFM estimated by isotope dilution (P less than 0.001). RMR in the women was also lower (0.84 +/- 0.02 kcal/min), but in contrast to the difference between young and old men, RMR adjusted for FFM did not differ (P = 0.16) between old men and women. Therefore, it is clear that differences in FFM cannot fully account for the lower RMR in the old, suggesting that aging is associated with an alteration in tissue energy metabolism.

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Domain-specific physical activity patterns and cardiorespiratory fitness among adults in Germany

European Journal of Public Health ◽

10.1093/eurpub/ckz185.639 ◽

2019 ◽

Vol 29 (Supplement_4) ◽

Author(s):

J Zeiher ◽

M Duch ◽

L E Kroll ◽

G B M Mensink ◽

J D Finger ◽

...

Keyword(s):

Physical Activity ◽

Cardiorespiratory Fitness ◽

Leisure Time ◽

Leisure Time Physical Activity ◽

Adult Population ◽

Activity Patterns ◽

Strong Association ◽

Maximal Oxygen Consumption ◽

Cycle Ergometer ◽

Physical Measurements

Abstract Background Studies show that occupational physical activity (OPA) has less health-enhancing effects than leisure-time physical activity (LTPA). The spare data available suggests that OPA rarely includes aerobic PAs with little or no enhancing effects on cardiorespiratory fitness (CRF) as a possible explanation. This study aims to investigate the associations between patterns of OPA and LTPA and CRF among adults in Germany. Methods 1,204 men and 1,303 women (18-64 years), who participated in the German Health Interview and Examination Survey 2008-2011, completed a standardized sub-maximal cycle ergometer test to estimate maximal oxygen consumption (VO2max). Job positions were coded according to the level of physical effort to construct an occupational PA index and categorized as low vs. high OPA. LTPA was assessed via questionnaires and dichotomized in no vs. any LTPA participation. A combined LTPA/OPA variable was used (high OPA/ LTPA, low OPA/LTPA, high OPA/no LTPA, low OPA/no LTPA). Information on potential confounders was obtained via questionnaires (e.g., smoking and education) or physical measurements (e.g., waist circumference). Multi-variable logistic regression was used to analyze associations between OPA/LTPA patterns and VO2max. Results Preliminary analyses showed that less-active men were more likely to have a low VO2max with odds ratios (ORs) of 0.80 for low OPA/LTPA, 1.84 for high OPA/no LTPA and 3.46 for low OPA/no LTPA compared to high OPA/LTPA. The corresponding ORs for women were 1.11 for low OPA/LTPA, 3.99 for high OPA/no LTPA and 2.44 for low OPA/no LTPA, indicating the highest likelihood of low fitness for women working in physically demanding jobs and not engaging in LTPA. Conclusions Findings confirm a strong association between LTPA and CRF and suggest an interaction between OPA and LTPA patterns on CRF within the workforce in Germany. Women without LTPA are at high risk of having a low CRF, especially if they work in physically demanding jobs. Key messages Women not practicing leisure-time physical activity are at risk of having a low cardiorespiratory fitness, especially if they work in physically demanding jobs. Different impact of domains of physical activity should be considered when planning interventions to enhance fitness among the adult population.

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A Clinical Method for Estimation of VO2max Using Seismocardiography

International Journal of Sports Medicine ◽

10.1055/a-1144-3369 ◽

2020 ◽

Vol 41 (10) ◽

pp. 661-668

Author(s):

Kasper Sørensen ◽

Mathias Krogh Poulsen ◽

Dan Stieper Karbing ◽

Peter Søgaard ◽

Johannes Jan Struijk ◽

...

Keyword(s):

Prediction Model ◽

Cardiorespiratory Fitness ◽

Demographic Data ◽

Cycle Ergometer ◽

Accurate Estimation ◽

Clinical Method ◽

Cycle Ergometer Test ◽

Aortic Valve Closure ◽

Proposed Model ◽

Ergometer Test

AbstractThe purpose of this study was to investigate the correlation between the seismocardiogram and cardiorespiratory fitness. Cardiorespiratory fitness can be estimated as VO2max using non-exercise algorithms, but the results can be inaccurate. Healthy subjects were recruited for this study. Seismocardiogram and electrocardiogram were recorded at rest. VO2max was measured during a maximal effort cycle ergometer test. Amplitudes and timing intervals were extracted from the seismocardiogram and used in combination with demographic data in a non-exercise prediction model for VO2max. 26 subjects were included, 17 females. Mean age: 38.3±9.1 years. The amplitude following the aortic valve closure derived from the seismocardiogram had a significant correlation of 0.80 (p<0.001) to VO2max. This feature combined with age, sex and BMI in the prediction model, yields a correlation to VO2max of 0.90 (p<0.001, 95% CI: 0.83–0.94) and a standard error of the estimate of 3.21 mL·kg−1·min−1 . The seismocardiogram carries information about the cardiorespiratory fitness. When comparing to other non-exercise models the proposed model performs better, even after cross validation. The model is limited when tracking changes in VO2max. The method could be used in the clinic for a more accurate estimation of VO2max compared to current non-exercise methods.

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Oxygen cost and oxygen uptake dynamics and recovery with 1 min of exercise in children and adults

Journal of Applied Physiology ◽

10.1152/jappl.1991.71.3.993 ◽

1991 ◽

Vol 71 (3) ◽

pp. 993-998 ◽

Cited By ~ 52

Author(s):

S. Zanconato ◽

D. M. Cooper ◽

Y. Armon

Keyword(s):

Time Course ◽

Significant Degree ◽

Cycle Ergometer ◽

Work Intensity ◽

O2 Uptake ◽

Ergometer Exercise ◽

Adults And Children ◽

The Difference ◽

Recovery Dynamics ◽

Best Fit

To test the hypothesis that O2 uptake (VO2) dynamics are different in adults and children, we examined the response to and recovery from short bursts of exercise in 10 children (7–11 yr) and 13 adults (26–42 yr). Each subject performed 1 min of cycle ergometer exercise at 50% of the anaerobic threshold (AT), 80% AT, and 50% of the difference between the AT and the maximal O2 uptake (VO2max) and 100 and 125% VO2max. Gas exchange was measured breath by breath. The cumulative O2 cost [the integral of VO2 (over baseline) through exercise and 10 min of recovery (ml O2/J)] was independent of work intensity in both children and adults. In above-AT exercise, O2 cost was significantly higher in children [0.25 +/- 0.05 (SD) ml/J] than in adults (0.18 +/- 0.02 ml/J, P less than 0.01). Recovery dynamics of VO2 in above-AT exercise [measured as the time constant (tau VO2) of the best-fit single exponential] were independent of work intensity in children and adults. Recovery tau VO2 was the same in both groups except at 125% VO2max, where tau VO2 was significantly smaller in children (35.5 +/- 5.9 s) than in adults (46.3 +/- 4 s, P less than 0.001). VO2 responses (i.e., time course, kinetics) to short bursts of exercise are, surprisingly, largely independent of work rate (power output) in both adults and children. In children, certain features of the VO2 response to high-intensity exercise are, to a small but significant degree, different from those in adults, indicating an underlying process of physiological maturation.

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Effect of duration of exercise on excess postexercise O2 consumption

Journal of Applied Physiology ◽

10.1152/jappl.1987.62.2.485 ◽

1987 ◽

Vol 62 (2) ◽

pp. 485-490 ◽

Cited By ~ 89

Author(s):

R. Bahr ◽

I. Ingnes ◽

O. Vaage ◽

O. M. Sejersted ◽

E. A. Newsholme

Keyword(s):

Rectal Temperature ◽

Time Course ◽

Control Experiment ◽

Respiratory Exchange Ratio ◽

Exercise Duration ◽

Cycle Ergometer ◽

O2 Consumption ◽

Work Intensity ◽

O2 Uptake ◽

Male Subjects

This study was undertaken to determine the effect of exercise duration on the time course and magnitude of excess postexercise O2 consumption (EPOC). Six healthy male subjects exercised on separate days for 80, 40, and 20 min at 70% of maximal O2 consumption on a cycle ergometer. A control experiment without exercise was performed. O2 uptake, respiratory exchange ratio (R), and rectal temperature were monitored while the subjects rested in bed 24 h postexercise. An increase in O2 uptake lasting 12 h was observed for all exercise durations, but no increase was seen after 24 h. The magnitude of 12-h EPOC was proportional to exercise duration and equaled 14.4 +/- 1.2, 6.8 +/- 1.7, and 5.1 +/- 1.2% after 80, 40, and 20 min of exercise, respectively. On the average, 12-h EPOC equaled 15.2 +/- 2.0% of total exercise O2 consumption (EOC). There was no difference in EPOC:EOC for different exercise durations. A linear decrease with exercise duration was observed in R between 2 and 24 h postexercise. No change was observed in recovery rectal temperature. It is concluded that EPOC increases linearly with exercise duration at a work intensity of 70% of maximal O2 consumption.

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