For many, running further or faster, or being fitter and healthier is a common goal. We often measure our fitness by the way we feel. However there is a more scientific measurement to determine fitness levels. Maximal oxygen uptake (VO2 max) is the maximum capacity of an individual’s body to transport and use oxygen during exercise. It is widely accepted as the single best measure of cardiovascular fitness.
The average untrained healthy male will have a VO2 max of approximately 35-40 ml/kg/min. The average untrained healthy female will score a VO2 max of approximately 27-31 ml/kg/min. Therefore absolute values of VO2 max are typically 40-60% higher in men than in women. A persons VO2 max will often decrease with age without training, though the degree of train-ability also varies very widely: conditioning may double VO2 max in some individuals, and will marginally improve it in others.
In sports where endurance is an important component in performance, such as running, rowing and cycling world class athletes typically have high VO2 max. With some elite male runners consuming up to 85 ml/kg/min, and female elite runners can consume about 77 ml/kg/min. The highest values in absolute terms are often found in rowers, as their much greater bulk makes up for a slightly lower VO2 max per kg.
VO2 max is effected by lactate threshold (LT). This is the point at which lactate (more specifically, lactic acid) starts to accumulate in the blood stream during exercise. This happens when lactate is produced faster than it can be removed in the muscle and signifies a significant shift from predominantly aerobic metabolism to predominantly anaerobic metabolism as the body begins to favour anaerobic energy systems. As the exercise intensity increases the lactate level in the blood reaches the ‘anaerobic threshold’ (AT), or the onset of blood lactate accumulation (OBLA).
The lactate threshold is a useful measure for deciding exercise intensity for training in endurance sports (e.g. long distance running, cycling, rowing and swimming), but varies between individuals and can be increased with training. High Intensity Interval Training (HIIT) takes advantage of the body being able to temporarily exceed the lactate threshold, and then recover (reduce blood-lactate) while operating below the threshold and while still doing physical activity.
Accurately measuring the lactate threshold involves taking blood samples (normally a pinprick to the finger, earlobe or thumb). While not many people have the ability to measure their own actual lactate threshold, there are tests that provide estimates. One simple way to estimate your lactate threshold is to perform a 30-minute time trial at a high, sustained pace. This test is suited to experienced athletes and should not be attempted by anyone who is not in top shape. The goal of this test is to exercise for 30 minutes at the highest effort that can be sustained and monitor your heart rate throughout the test. Your average heart rate during the final 20 minutes should correspond to your LT.
30-Minute Time Trial for Estimating LT
• You can perform this test by running, cycling, swimming or doing another endurance sport that can be sustained for 30 minutes
• You will need a heart rate monitor and a way to capture splits
• Warm up for 15 minutes
• Begin exercise and work up to the your peak, sustained intensity within the first 10 minutes
• Record your heart rate each minute for the last 20 minutes
• Calculate your average heart rate over the last 20 minutes
• This figure is your estimated heart rate at your lactate threshold
Those PT clients that have undertaken a running session with me will know we produce a heart rate figure at which you can sustain a high running pace, this would be your estimated LT heart rate!
In theory an individual could exercise at any intensity up to their VO2 max indefinitely. As exercise intensity draws closer to VO2 max however a sharp increase in blood lactate accumulation and subsequent fatigue occurs as the lactate threshold is broken.
Generally, in two people with the same VO2 max, the one with the higher lactate threshold will perform better in continuous-type endurance events, such as running, see graph left. Although both Athlete 1 and Athlete 2 reach VO2 max at a similar running speed, Athlete 1 has a lactate threshold at 70% and Athlete 2 has a lactate threshold at 60%. Theoretically, Athlete 1 can maintain a pace of about 7.5mph compared to Athletes 2s pace of about 6.5mph.
With training, lactate threshold as a percentage of VO2 max can be increased. Even if there are no improvements in maximal oxygen uptake increasing the relative intensity or speed at which lactate threshold occurs will improve performance. In effect, proper training can shift the lactate curve to the right! (see graph below) Training at or slightly above lactate threshold can increase the relative intensity at which it occurs.
If you would like to know more about Lactate Threshold or to improve your performance please contact Mark on 07771 985015
