Sustainable Pace: Field Test

For a runner to evaluate their training effect (TE) it is important to learn how to monitor their sustainable pace. The sustainable pace(s) is an intensity level that you can sustain w/out accelerating the release of fatigue related waist products and the acidosis that accumulates when you are training at or above the lactate threshold (LT). In the lab you can evaluate this effect by determining the changes in speed (or power) and oxygen consumption levels (VO2) at the Lactate or ventilatory thresholds. See Lactate Threshold.

Lab testing can distinguish how the runner has physiologically adapted to improve his or her sustainable pace since we can observe the actual changes in oxygen consumption (i.e., metabolic fitness). Where as, speed changes at LT could represent both the economy of motion changes as well as those metabolic fitness changes. Knowing this is important because without all that information we typically are only guessing if your fitness is lifting up your pace to it's potential. Even using time trial speeds or race results may not be the best indicators of how well your body is adapting to your training plan. Time trials (TT) rely on your fastest effort for 30-60 minutes which can represent; your effort, metabolic fitness, economy and anaerobic (above LT) endurance changes. This may work well for endurance events that last fewer than a couple of hours, however if your event requires longer efforts (i.e., marathons) the anaerobic component to the TT may not reflect how well you can actually sustain the sub-threshold paces involved in the longer races or efforts. Similarly, if you evaluate your TE by your races only you can't be sure if the slower than goal pace was due to poor pacing, weather, fueling, effort, dehydration, overtraining or low fitness.

Although lab testing is your best bet to evaluate your TE the feasibility of regular testing every month is low due to limiters like cost and logistics. Another option that can be included along with periodic lab testing is to evaluate sustainable pace by using a field test that can monitor your pace changes at a constant subthreshold heart rate. One way to do this is to choose a heart rate that is about 10 beats below your lactate threshold heart rate and then run a 1 mile time trial at that heart rate. If the mile time decreases at the targeted HR from test to test than your sustainable pace is improving. This is a relatively safe test as well as a great field test to determine your TE for races or events that take longer than 2-3 hours.

To start tracking your Sustainable Pace check out this tool: Sustainable Pace Tracker.