Part II of this series was supposed to look at equipment and efficiency, two major contributors to performance. But based on the number of requests I've received relative to the first installment of The Masters Skater, we'll instead focus on the topic of Lactate Threshold and how it is related to performance, along with ways to train for improving it. Before we delve in to those areas, let's take a bit of a "refresher course" on the components of athletic performance and how they are altered by the aging process.

We are looking at athletic performance in sports such as inline skating, running, and cycling which require muscles to repeatedly exert forces through a range of motion for an extended time (dependent on the distance traversed). In inline skating, the distances are anywhere from a sprint to a marathon. Most of the focus of this series is on the "aerobic distance" races (10K - marathon).

Recap

The major contributors to performance in this subset are physiology (VO₂, lactate threshold (LT)), biomechanics (efficiency, equipment), and mental considerations (preparation, strategy, tactics). In Part I (physiology) we noted: max VO₂ typically declines with age; the decline can be offset to a large degree with proper training; lactate threshold is a significant contributor to performance, since we are only able to use that portion of our max VO₂ that is "sustainable" for the duration of a race; and we can pretty much maintain our LT as we age, if we maintain a threshold volume and intensity of training. Now, a bit more about the LT.

Tricky Little Thing Called LT

The lactate threshold (LT)) is a tricky thing. Although you may be able to determine what your LT is (see Photo) through human performance lab tests, with blood-sampling and multiple bouts of exertion at various levels, you need to know that your LT changes with training, muscle fiber-type (which "changes" with training), distribution of blood flow (which changes when heat dissipation becomes a factor, as during a hot, humid race), and distribution of work load (applying force with a smaller muscle mass versus a larger number of muscles); and the percentage of your LT that you will want to maintain will depend on, among other things, the distance of the race you're entering. It's not simply an issue of finding out what your heart rate is at your LT; it's much more complicated than that.

The graph below depicts the results of a typical LT test. In Part I, we described two skaters, Joe and Mike. These test results are from our fictitous skater Mike. Notice how the lactate concentration increases slowly, then much faster, as the oxygen consumption increases. At low workload levels, the lactate concentration in the blood remains fairly low (near 1 - typical resting level). As workload increases, the lactate concentration increases until, at a point, it starts to increase in a non-linear fashion (curved line behind the lactate concentration data points). Theoretically, this point is your LT. As you can see, it is not a clearly-defined point, and there is much controversy in terms of "where" the LT occurs.

If you look at the dashed line coming in to the graph from the left, it points to this lactate concentration. In addition, the dashed line pointing downward from that lactate concentration data point points to the oxygen consumption level at the LT(in this case, approximately 45 ml/kg/min). Finally, the left-facing, horizontal dashed line that starts at the heart rate directly above the "breakpoint" lactate concentration shows the heart rate at MIke's LT (in this case, 150 beats/min).

When calculated as a percentage of a person's max VO₂, their LT will typically fall into a range of approx. 60% to 90%. Untrained individuals will, of course, have the lowest values, while many masters athletes will rank near the 80% mark. Some elite athletes can rank even higher; near the 90% mark. Looking at the graph, we can see that Mike's LT occurs at approximately 78% of his max VO₂ (42.9 ml/kg/min LT VO₂ divided by his 55 ml/kg/min max VO₂).

Now I Know... So What?

Great. Now we know (theoretically) our LT. What do we do with it? It would seem obvious, train at that level. Well, as it happens, athletes do not use 100% of their LT during many races, and in training, it has its place as well. In fact, the percentage of LT that can be sustained varies according to the duration of the event. For example, in a 10K race, you can skate at a level slightly above your LT, while in a marathon, you would need to stay slightly below your LT. In a two to three hour skate race, you'll need to stay at a level comfortably below your LT. But how can you skate above your LT? You learn to deal with the discomfort of skating with an accumulation of lactic acid in your muscles. There are physiological reasons why you cannot skate tremendously above your LT for extended periods of time, but a highly motivated, extremely well-conditioned athlete can sustain a power output representing their max VO₂ (a value significantly higher than their LT) for nearly an hour. Longer bouts of exercise carried on at that level would ultimately produce too much lactate to continue exercising without reducing the workload.

How to Use the Information

So you need to keep in mind - once you find out your LT - that you won't be working at that level all of the time. For endurance training, you'll want to train with a heart rate equivalent to some 20 beats or so below your LT heart rate. For speed work, you can train with your heart rate at or near your LT heart rate, and for short bursts, exceed your LTheart rate.

Using the example graph above, and the information from Part I, if Mike had a max vo₂ of 55 ml/kg/min and a lactate threshold that occurred at 42.9 ml/kg/min, his lactate threshold heart rate ( LTHR) is 150 beats/min. This represents 78% of his max vo₂, but it represents 83% of his max heart rate (HR) - 180 beats/min (see Table below). By using this information, Mike could setup a solid plan for his training. During his initial endurance build-up phase, he would keep his exercise HR approx. 20 beats/min below his LTHR and his exercise HR at or below 130 beats/min. This training HR would represent 72% of his max HR; a figure consistent with conventional fitness training information. It would represent 63% of his max vo₂, which is consistent with conventional wisdom. This level of training would be appropriate for 6-12 weeks of training (during a base-building period), contingent on the idea that he is training for distances of 10K or greater. For speed work, he would achieve and maintain an exercise HR close to 150 beats/min, and for short bursts, a higher HR.

Of course, all of this is dependent on the LTHR not changing (which, in reality, it does). Since we know the LTHR changes as a result of training (among other things), it is a good idea to have your LTHR re-measured occasionally during training - especially during the first 3 months of your program, where much change is likely to occur. Once a new LTHR has been established, the training principles apply to the new LTHR .

Note: HR can be quite variable. Heat, humidity, time of day, ingestion of caffeine or other substances, and others can have a significant effect on your HR; it should be used mainly as a guide. Your perception of your effort level is usually a good indicator of your body's physiologic load - listen to it.

While this information is not just for master athletes, it does provide "hope" for the masters athlete who is concerned that their max vo₂ and max HR are declining. Numerous masters athletes have increased their LT to a level that they did not previously experience, allowing them to go faster and farther than ever before. In fact, since efficiency (which I promise we'll discuss) can also be enhanced through repeated training, the masters athlete has yet another "leg up" on the younger skater.

I promised many of the respondents to the first installment that I would cover LT in this issue, and how to do your own "lab test" of LT in another issue. So, unless anyone has any strong objections, the topics of equipment and efficiency will be pushed back another issue, so we can use Part III to describe how to do a "relative" of an LT test on yourself, and get all of you worked up about how fast you can go.

In Part I, three masters endurance athletes were highlighted in order to demonstrate the fact that elite level performances are quite possible once an athlete reaches the "Masters" level age of 30. Just to be fair, here's another world-record performance by a masters athlete - this time, a sprint event athlete. In ‘95, Britain's Linford Christie broke the world indoor record in the 200m. Christie set the mark with a time of 20.25 at the age of 34.