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     Juerg Senior Member Username: Juerg Post Number: 1965 Registered: 04-2006 |
Here an example and the regular readers will see that question somewhat different than new readers. Here very short. Using a % of VO2 max and throw this to all people involved in the research means , that they work out at the same mathematical intensity as the will work by 75 % of their VO2 max. Question `is this as well the same physiological intensity for all the people. How about the possibility , that some may go O2 dependent nicely at 75 % of VO2 max, some may just be at the border line and some may be already very heavy in the O2 independent intensity involvement. So if we train them by 75 % for the same time can we expect the same reaction and stimulus on their systems . Here to read and you give the answer on the result. In previously sedentary people, training at 75% of aerobic power, for 30 minutes, 3 times a week over 6 months increases VO2 max an average of 15-20% (6). However, this is an average and there are large individual variations with increases as wide ranging as 4% to 93% reported (6). Amongst groups of people following the same training protocol there will be responders - those who make large gains, and non-responders - those who make little or no gains (14,9). This was originally put down to a simple issue of compliance but more recent research suggests that genetics plays a role in how well any one individual responds to an endurance training program (13). | ||
| Juerg Senior Member Username: Juerg Post Number: 1966 Registered: 04-2006 |
Here one possible answer from one of the authors himself: Crucially, once a plateau in VO2 max has been reached further improvements in performance are still seen with training. This is because the athlete is able to perform at a higher percentage of their VO2 max for prolonged periods (2). Two major reasons for this are improvements in anaerobic threshold and running economy And as a nice follow up for all fans`of interval as a common ongoing discussion : `Resistance training and intense 'burst-type' anaerobic training have little effect on VO2 max. Any improvements that do occur are usually small and in subjects who had a low level of fitness to begin with (17). Resistance training alone does not increase VO2 max (30,31,32) even when short rest intervals are used between sets and exercises (33). | ||
| Juerg Senior Member Username: Juerg Post Number: 1967 Registered: 04-2006 |
VO2 Max as a Predictor of Performance In elite athletes, VO2 max is not a good predictor of performance. The winner of a marathon race for example, cannot be predicted from maximal oxygen uptake (15). Perhaps more significant than VO2 max is the speed at which an athlete can run, bike or swim at VO2 max. Two athletes may have the same level of aerobic power but one may reach their VO2 max at a running speed of 20 km/hr and the other at 22 km/hr. While a high VO2 max may be a prerequisite for performance in endurance events at the highest level, other markers such as lactate threshold are more predictive of performance (3). Again, the speed at lactate threshold is more significant than the actual value itself. Think of VO2 max as an athlete’s aerobic potential and the lactate threshold as the marker for how much of that potential they are tapping | ||
| Juerg Senior Member Username: Juerg Post Number: 1968 Registered: 04-2006 |
As you will see, there is one system missing in the òld `discussion. Which one Factors Affecting VO2 Max There are many physiological factors that combine to determine VO2 max but which of these are most important? Two theories have been proposed: Utilization Theory This theory maintains that aerobic capacity is limited by lack of sufficient oxidative enzymes within the cell's mitochondria (3). It is the body's ability to utilize the available oxygen that determines aerobic capacity. Proponents of this theory point to numerous studies that show oxidative enzymes and the number and size of mitochondria increase with training. This is coupled with increased differences between arterial and venous blood oxygen concentrations (a-vO2 difference) accounting for improved oxygen utilization and hence improved VO2max. Presentation Theory Presentation theory suggests that aerobic capacity is limited not predominantly by utilization, but by the ability of the cardiovascular system to deliver oxygen to active tissues. Proponents of this theory maintain that an increase in blood volume, maximal cardiac output (due to increased stroke volume) and better perfusion of blood into the muscles account for the changes in VO2max with training. So what plays the greater role in determining an athlete's VO2 max - their body's ability to utilize oxygen or supply oxygen to the active tissues? In a review of the literature, Saltin and Rowell (7) concluded that it is oxygen supply that is the major limiter to endurance performance. Studies have shown only a weak relationship between an increase in oxidative enzymes and an increase in VO2 max (8,9,10). One of these studies measured the effects of a 6-month swim training program on aerobic function. While oxidative enzymes continued to increase until the end, there was no change in VO2 max in the final 6 weeks of the program (10). Yes the respiratory system. | ||
| Juerg Senior Member Username: Juerg Post Number: 1969 Registered: 04-2006 |
VO2 Max at Altitude VO2 max decreases as altitude increases above 1600m (5249ft) or about the altitude of Denver, Colorado. For every 1000m (3281ft) above that, maximal oxygen uptake decreases further by approximately 8-11% (3). Anyone with a VO2 max lower than 50 ml/kg/min would struggle to survive at the summit of Everest without supplemental oxygen. The decrease is mainly due to a decrease in maximal cardiac output. Recall that cardiac output is the product of heart rate and stroke volume. Stoke volume decreases due to the immediate decrease in blood plasma volume. Maximal heart rate may also decrease and the net effect is that less oxygen is "pushed" from the blood into the muscles (2). |