Article

VO2max: what do we know, and what do we still need to know? J Physiol

Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, 7232 Greenville Avenue, Dallas, TX 75231, USA.
The Journal of Physiology (Impact Factor: 5.04). 02/2008; 586(1):25-34. DOI: 10.1113/jphysiol.2007.147629
Source: PubMed

ABSTRACT

Maximal oxygen uptake (.VO(2,max)) is a physiological characteristic bounded by the parametric limits of the Fick equation: (left ventricular (LV) end-diastolic volume--LV end-systolic volume) x heart rate x arterio-venous oxygen difference. 'Classical' views of .VO(2,max) emphasize its critical dependence on convective oxygen transport to working skeletal muscle, and recent data are dispositive, proving convincingly that such limits must and do exist. 'Contemporary' investigations into the mechanisms underlying peripheral muscle fatigue due to energetic supply/demand mismatch are clarifying the local mediators of fatigue at the skeletal muscle level, though the afferent signalling pathways that communicate these environmental conditions to the brain and the sites of central integration of cardiovascular and neuromotor control are still being worked out. Elite endurance athletes have a high .VO(2,max) due primarily to a high cardiac output from a large compliant cardiac chamber (including the myocardium and pericardium) which relaxes quickly and fills to a large end-diastolic volume. This large capacity for LV filling and ejection allows preservation of blood pressure during extraordinary rates of muscle blood flow and oxygen transport which support high rates of sustained oxidative metabolism. The magnitude and mechanisms of cardiac phenotype plasticity remain uncertain and probably involve underlying genetic factors, as well as the length, duration, type, intensity and age of initiation of the training stimulus.

    • "When the duration of maximal exercise is increased, the body begins to increasingly rely on the aerobic system to produce energy [11]. This in turn increases oxygen uptake and, with it, heart rate [2] [15]. The above physiological responses allow the body to perform at a high exercise intensity while at the same time causes the onset of fatigue to accelerate [11]. "
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    ABSTRACT: BACKGROUND: While interval training is considered an effective modality for improving physical performance, it is still unclear how to monitor and determine optimal training load. OBJECTIVE: The study aimed to identify differences in power, heart rate, and acid-base balance in response to a single interval training session in cyclists. METHODS: The research involved 21 mountain cyclists experienced and inexperienced with interval training. The interval training test consisted of several sets (4-6, until exhaustion) of maximal intensity exercise on a cycle-ergometer. Each set comprised four 30-s repetitions interspersed with 90-s recovery periods. Peak power, work output, heart rate, hydrogen and lactate ion concentrations were measured. RESULTS: The cyclists experienced with interval training performed significantly more (p< 0.01) sets than inexperienced cyclists (5.6 ± 1.0 vs. 4.5 ± 0.8 sets, respectively). Power and work output decreased in the last completed set only in the inexperienced group (660.5 ± 53.6 vs. 659.9 ± 71.3 W and 666.6 ± 63.3 vs. 633.7 ± 86.8 W in the first and last sets for the experienced and inexperienced cyclists, respectively). The experienced group showed a decrease in hydrogen ion accumulation in the fourth set; in the inexperienced group this occurred in the second set. The experienced group showed lower heart-rate recovery times after the last set. CONCLUSIONS: Cyclists experienced with interval training could perform more repeated bouts of exercise with a disrupted acid-base balance at a similar performance level than inexperienced cyclists.
    No preview · Article · Nov 2015 · Isokinetics and exercise science
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    • "For endurance athletes, maximal oxygen consumption allows a more appropriate and objective classification, because this variable is considered " gold-standard " and predicts time-trial performance [22]. This is due to the concept that an athlete's maximal oxygen consumption is mainly determined by the oxygen delivery to the mitochondria and its utilization, which in turn are limiting the oxidative production of ATP required for the energy supply of the working muscles [23]. As neural efficiency is task-related, it is necessary to study brain cortical activity in athletes directly during endurance exercise. "
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    ABSTRACT: The “neural efficiency” hypothesis suggests that experts are characterized by a more efficient cortical function in cognitive tests Although this hypothesis has been extended to a variety of movement-related tasks within the last years, it is unclear whether or not neural efficiency is present in cyclists performing endurance exercise. Therefore, this study examined brain cortical activity at rest and during exercise between cyclists of higher (HIGH; n=14 ;55.6 ± 2.8 mL/min/kg) and lower (LOW; n=15; 46.4 ± 4.1 mL/min/kg) maximal oxygen consumption (VO2MAX ). Male and female participants performed a graded exercise test with spirometry to assess VO2MAX. After 3 to 5 days, EEG was recorded at rest with eyes closed and during cycling at the individual anaerobic threshold over a 30 min period. Possible differences in alpha/beta ratio as well as alpha and beta power were investigated at frontal, central, and parietal sites. The statistical analysis revealed significant differences between groups, as the alpha/beta ratio was increased in HIGH compared to LOW in both the resting state and the exercise condition. The present results indicate enhanced neural efficiency in subjects with high VO2MAX, possibly due to the inhibition of task-irrelevant cognitive processes.
    Full-text · Article · Oct 2015 · Neural Plasticity
    • "Variables significantly associated with VO 2peak in bivariate analysis were entered into the regression model as independent variables. Additionally, multiple regression analyses forcing the inclusion of potential causative variables (Q peak , haemotological variables, capillary-to-fibre ratio, total Mito VD , ST cross-sectional area) based on established underlying physiology (di Prampero & Ferretti, 1990; Bassett & Howley, 2000; Levine, 2008 "
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    ABSTRACT: It remains unclear whether improvements in peak oxygen uptake (VO2peak ) following endurance training (ET) are primarily determined by central and/or peripheral adaptations. Herein, we tested the hypothesis that the improvement in VO2peak following 6 weeks of ET is mainly determined by haematological rather than skeletal muscle adaptations. Sixteen untrained healthy male volunteers (age = 25 ± 4 years, VO2peak = 3.5 ± 0.5 l min(-1) ) underwent supervised ET (6 weeks, 3-4 sessions/week). VO2peak , peak cardiac output (Qpeak ), haemoglobin mass (Hbmass ) and blood volumes were assessed prior to and following ET. Skeletal muscle biopsies were analysed for mitochondrial volume density (MitoVD ), capillarity, fibre types and respiratory capacity (OXPHOS). After the post ET assessment, red blood cell volume (RBCV) was re-established to the pre ET level by phlebotomy and VO2peak and Qpeak were measured again. We speculated that the contribution of skeletal muscle adaptations to the ET-induced increase in VO2peak would be revealed when controlling for haematological adaptations. VO2peak and Qpeak were increased (P < 0.05) following ET (9 ± 8 and 7 ± 6 %, respectively) and decreased (P < 0.05) after phlebotomy (-7 ± 7 and -10 ± 7 %). RBCV, plasma volume and Hbmass all increased (P < 0.05) after ET (8 ± 4, 4 ± 6 and 6 ± 5 %). As for skeletal muscle adaptations, capillary-to-fibre ratio and total MitoVD increased (P < 0.05) following ET (18 ± 16 and 43 ± 30 %), but OXPHOS remained unaltered. Through stepwise multiple regression analysis, Qpeak , RBCV and Hbmass were independent predictors of VO2peak . In conclusion, the improvement in VO2peak following 6 weeks of ET is primarily attributed to increases in Qpeak and oxygen-carrying capacity of blood in untrained healthy young subjects. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Aug 2015 · The Journal of Physiology
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