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  • 1985-1989  (3)
  • 1975-1979
  • Maximum oxygen uptake  (3)
  • 1
    ISSN: 1439-6327
    Schlagwort(e): Respiratory exchange ratio ; Maximum oxygen uptake ; Dietary manipulation ; Maximal incremental exercise
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary This study examined the effects of dietary manipulation upon the respiratory exchange ratio ( $$R = \dot V_{{\text{CO}}_{\text{2}} } /\dot V_{{\text{O}}_{\text{2}} } $$ ) as a predictor of maximum oxygen uptake ( $$\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} } $$ ). Seven healthy males performed fixed term maximal incremental treadmill exercise after an overnight fast on three separate occasions. The first test took place after the subjects had consumed their normal mixed diet (45±5% carbohydrate (CHO)) for a period of three days. This test protocol was then repeated after three days of a low CHO diet (3±2% CHO), and again after three days of a high CHO diet (61±5% CHO). Respiratory gases were continuously monitored during each test using an online system. No significant changes in mean exercise oxygen uptake ( $$\dot V_{{\text{O}}_{\text{2}} } $$ ), $$\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} } $$ or maximum functional heart rate (FHRmax) were found between tests. Mean exercise carbon dioxide output ( $$\dot V_{{\text{CO}}_{\text{2}} } $$ ) and R were significantly lower than normal after the low CHO diet (bothp〈0.001) and significantly higher than normal after the high CHO diet (bothp〈0.05). Moreover, compared with the normal CHO diet, the R-time relationship during exercise was at all times significantly (p〈0.001) shifted to the right after the low CHO diet, and shifted to the left, being significantly so (p〈0.05) over the final 5 min of exercise, after the high CHO diet. As a result, predictions of $$\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} } $$ based on the R-time relationship were similar to recorded $$\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} } $$ after the normal CHO dietary condition (-1.5±1.9%), but higher after the low CHO diet (+14.8±3.9%,p〈0.001) and lower after the high CHO diet (−7.0±4.5%,p〈0.01). These results indicate that dietary manipulation can significantly affect respiratory gas exchanges during fixed term maximal incremental exercise, and by doing so can significantly influence predictions of $$\dot V_{{\text{O}}_{{\text{2}} {\text{max}}} } $$ based on R.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of applied physiology 57 (1988), S. 714-719 
    ISSN: 1439-6327
    Schlagwort(e): Respiratory $$\dot V_{CO_2 } /\dot V_{O_2 }$$ exchange ratio ; Incremental exercise ; Treadmill ; Maximum oxygen uptake ; Prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The purpose of this study was to define carefully the dynamic relationship between oxygen uptake (as% $$\dot V_{O_{2\max } }$$ ) and the respiratory $$\dot V_{CO_2 } /\dot V_{O_2 }$$ exchange ratio (R) during maximum progressive treadmill exercise in trained and untrained men, and to determine if this relationship could be used to predict $$\dot V_{{\text{O}}_{{\text{2max}}} } $$ . Respiratory gases were continuously monitored and the % $$\dot V_{{\text{O}}_{{\text{2max}}} } $$ /R time profile calculated at 15 sec intervals over the final 5 min of each test. Young sedentary men (controls,n = 122) and over −60y sedentary men (n = 30) shared the same % $$\dot V_{{\text{O}}_{{\text{2max}}} } $$ /R relationship but the latter group had lower R values at $$\dot V_{{\text{O}}_{{\text{2max}}} } $$ (1.06±0.03 vs 1.08±0.03,P〈0.01) than controls. Endurance trained men (n = 45) had a lower % $$\dot V_{{\text{O}}_{{\text{2max}}} } $$ /R relationship and higher R at $$\dot V_{O_{2\max } }$$ (1.11±0.02,P〈 0.001), team athletes (n = 98) had a lower% $$\dot V_{O_{2\max } }$$ /R relationship but lower R at $$\dot V_{O_{2\max } }$$ (1.06±0.03,P〈0.001) and the weight trained (n = 19) had a higher% $$\dot V_{O_{2\max } }$$ /R relationship and lower R at $$\dot V_{O_{2\max } }$$ (1.01±0.02,P〈 0.001) all compared to controls. From the % $$\dot V_{O_{2\max } }$$ /R time profile, the following formulae were devised for the estimation of $$\dot V_{O_{2\max } }$$ ( $$\dot V_{O_{2\max } }$$ R): Young Sedentary, $$\dot V_{O_{2\max } }$$ R = $$\dot V_{O_2 }$$ R (3.000 −1.874 R); Over −60y Sedentary, $$\dot V_{O_{2\max } }$$ R = $$\dot V_{O_2 }$$ R (3.457-2.345 R); Endurance Trained, $$\dot V_{O_{2\max } }$$ = $$\dot V_{O_2 }$$ R (1.980–0.912 R); Team Athletes, $$\dot V_{O_{2\max } }$$ R = $$\dot V_{O_2 }$$ R (2.805−1.726 R); Weight Trained, $$\dot V_{O_{2\max } }$$ R = $$\dot V_{O_2 }$$ R (4.236−3.191 R). Comparison of recorded $$\dot V_{O_{2\max } }$$ and the estimated $$\dot V_{O_{2\max } }$$ R values showed no significant differences in any of the groups examined (r = 0.89–0.90,p〈 0.001). These results suggest the R response to maximum incremental exercise may be influenced by different types of physical training, and that specific formulae derived from the % $$\dot V_{O_{2\max } }$$ /R relationship can provide a precise estimate of $$\dot V_{O_{2\max } }$$ for individuals.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    European journal of applied physiology 57 (1988), S. 720-725 
    ISSN: 1439-6327
    Schlagwort(e): Respiratory $$\dot V_{CO_2 } /\dot V_{O_2 }$$ exchange ratio ; Maximum oxygen uptake ; Maximum exercise ; Prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The present study examined the effect of previous severe exercise upon (i) respiratory exchange during maximal exercise, and (ii) the respiratory $$\dot V_{CO_2 } /\dot V_{O_2 }$$ exchange ratio (R) as a predictor of maximum oxygen uptake ( $$\dot V_{O_{2\max } }$$ )- Thirteen healthy males performed a progressive treadmill test to $$\dot V_{O_{2\max } }$$ : at rest (T1); after a 1 h run on the level treadmill at a speed corresponding 82.4±7.3% of their $$\dot V_{O_{2\max } }$$ (T2); after 1 h recovery (T3); and after 24 h recovery (T4). Respiratory gases were continuously monitored. No changes in average work $$\dot V_{O_2 }$$ , $$\dot V_{O_{2\max } }$$ or maximum heart rate were found between trials. Average work $$\dot V_{CO_2 }$$ was lower in T2 (2.055±0.093 l·min−1,p〈0.001), T3 (2.080±0.087 l·min−1,p〈0.001) and T4 (2.337±0.154 l·min−1, NS) compared with T1 (2.360±0.147 l·min−1). This resulted in lower average R values in T2 (0.81±0.02,P〈0.001), T3 (0.83±0.02,P〈0.001) and T4 (0.94±0.02, NS) in relation to T1 (0.95±0.02). Analysis of the % $$\dot V_{O_{2\max } }$$ /R relationship over the final 5 min of each test showed a shift to the left during T2 (p〈0.001), T3 (p〈0.001) and T4 (NS) compared with T1. As a result predictions of $$\dot V_{O_{2\max } }$$ based on R ( $$\dot V_{O_{2\max } }$$ R) were similar to recorded $$\dot V_{O_{2\max } }$$ in T1 (+0.6%) and T4 (+2.2%). But higher in T2 (+8.7%,p〈0.001) and T3 (+6.9%,p〈0.001). The present results show that previous severe exercise can significantly affect respiratory exchange at rest and during maximum incremental exercise, and by doing so can significantly influence predictions of $$\dot V_{O_{2\max } }$$ based on R.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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