The Sustainable % VO2max is the percent of VO2max that can be sustained during a race. As race distance increases the % VO2max that can be sustained decreases – typically well trained athletes can run at close to 100% VO2max during a 5km race (~98% VO2max) but this decreases significantly to around 92% during a 10km and 78% during a marathon. In order to maximize performance athletes must be able to sustain a pace that is as close to VO2max as possible. Research suggests that this is particularly important in races of greater than 30 minutes duration and appears to become increasingly important as race duration increases (Ghosh, 2004; Lucia et al., 2001; Fallowfield and Wilkinson, 1999; Coetzer et al., 1993; Coyle et al., 1995; Costil et al., 1973).
Over shorter duration races (e.g. 1500m-5km) the sustainable %VO2max appears to be less important – research looking at the sustainable % VO2max during a 5km race did not find any relationship between the %VO2max sustained and 5km race performance (Støa et al., 2010). This is not surprising since athletes are able to race at close to there VO2max during races of <5km and therefore there is little scope to improve the sustainable % VO2max in these events. However, as race duration increases it becomes harder to maintain a pace that is close to the maximal oxygen consumption, and the sustainable %VO2max becomes increasingly important, with even small differences in %VO2max sustained (e.g. 1-2% improvement) having a significant effect on race performance.
Factors Influencing The Sustainable % VO2max
The %VO2max sustained seems to be dependent on a number of factors including the aerobic capacity of the active muscles, the percentage of type I muscle fibres (Coyle et al., 1991 & 1995;), muscle capillary density (Coyle et al., 1988), and is strongly linked to the lactate threshold (Coetzer et al., 1993) and the VO2 at the lactate threshold (Coyle et al., 1988).
Individual variation in the %VO2max that can be sustained
The sustainable %VO2max can vary widely between individuals and can help to explain differences in race performance over varying distances. Generally, if two athletes have equal VO2max and vVO2max then the athlete with the highest sustainable % VO2max will win in a race situation of 30mins+ duration. However, it must be remembered that the sustainable % VO2max decreases as race distance increases and the rate of decrease varies from athlete to athlete – e.g. marathon specialists are able to sustain a much higher %VO2max than non-specialists over marathon distance but may have a lower or similar sustainable %VO2max over shorter distances like the 10km.
Assessing the Sustainable % VO2max
The %VO2max sustained can be evaluated under laboratory conditions, by measuring oxygen uptake at average race pace, at average power output, or, during a treadmill/cycle ergometer time trial. The VO2 sustained is then converted to a percentage of VO2max from a recent VO2max test. The %VO2 can also be established by comparing race pace/power outputs with laboratory recorded VO2 values from a recent incremental exercise.
Improving the Sustainable %VO2max
Since, the sustainable %VO2max appears to be strongly linked to the muscles aerobic capacity, muscle capillary density and the VO2 at the lactate threshold, training should focus primarily on enhancing the muscles aerobic capacity. It is therefore important that training volume is sufficient to maximize the muscles oxidative capacity. In addition athletes should include an adequate amount of lactate threshold training – a speed/power output that is at or slightly below the lactate threshold – to enhance muscle aerobic capacity, increase the lactate threshold and ultimately the sustainable %VO2max. It is important to remember that during races of shorter duration (e.g. 5-10km) there is a more limited scope for improvement in the sustainable %VO2max than in longer duration races like the marathon so the amount of time devoted to improving the sustainable %VO2max should be dependent on race duration.
Summary of Sustainable %VO2max
- The %VO2max that can be sustained is an important factor in endurance events of greater than 30 minutes.
- The sustainable %VO2max is less important in shorter events but becomes increasingly important as race distance increases.
- Factors influencing the sustainable %VO2max include the muscle capillary density, % type I muscle fibres, muscle capillary density, aerobic capacity of the muscle, the LT and the LTVO2.
- The sustainable %VO2max can vary greatly between individuals with some individuals better suited to longer duration races (e.g. marathon) whilst other suited to shorter duration races (e.g. 5km).
- Training to improve the sustainable %VO2max should concentrate on maximizing the muscles aerobic capacity (e.g. adequate volume of moderate intensity training, tempo training).
- The scope for increase in the sustainable %VO2max is less in shorter duration races (e.g. 5km) than longer races (e.g. marathon).