Lactic Testing and Field Testing for Cycling
Fromwheel hub to crank arm to pedals, cycling power meters have become increasingly sophisticated and popular. In fact, there was a 14 per cent increase in the use of power measurement devices at the 2013 Ironman World Championships (from 20 per cent in 2012 to 34 per cent). Furthermore, many pros made their race data available to viewers online within minutes of finishing the bike leg.
Measured in watts, power is the absolute value put to the pedals. It allows the athlete and coach to precisely measure the work that is being done: 200 watts is 200 watts. Because of this the athlete can be sure of going easy on recovery days and hard enough during intervals. While heart rate is often used to determine effort or pace, it’s subject to the effects of fatigue, temperature, altitude or diet. Power allows athletes to quantify when they are feeling strong or tired; on a good day he or she may require 60 per cent maximum heart rate to achieve a wattage that on another day may require 65 per cent maximum heart rate.
In order to use a power meter effectively, one has to determine the appropriate power ranges that stress the various energy systems the human body is able to call upon. There a number of different schools of thought regarding how to define and differentiate these energy systems based upon physiological cost and the time the athlete is able to work in each zone. The most common system used by coaches and athletes today is lactate threshold rather than maximum heart rate.
Contrary to popular belief, lactate is not an evil, burning solution that courses through your veins when you work hard. It’s a natural by-product of the muscles burning glucose and pyruvate in the presence of oxygen to form atp, the energy used to contract the muscle. Lactate is returned to the liver to be reprocessed and turned back into glucose. When the blood stream, liver and/ or glycogen levels in the body are unable to keep up with this process, we reach our aerobic threshold (muscles are using the oxygen in the blood to help with atp creation). This is typically what we call lactate threshold, above which, the muscles are no longer able to get enough oxygen and the system goes anaerobic which can only be maintained for a short time.
With lactate blood testing meters, one can determine a fairly accurate point where the effort goes from aerobic to anaerobic. Lactate levels are measured in millimols per litre (mmol/ L) and the current process bases threshold when the lactate content reaches four mmol/ L or there is an abrupt change in lactate values. Keep in mind this point is not an on/off switch, it happens over a relatively narrow heart rate range. This effort also coincides with the maximum effort one can maintain for 45 minutes to an hour and, when using power, is known as functional threshold power or ftp. An individual’s power zones are then derived from this value.
The two ways to determine threshold power are either step test (a gradual increase in load), or a short time trial. During a step test, the athlete rides on a trainer that has controllable power resistance, like a CompuTrainer. After a warm-up of 15 to 20 minutes, the test starts off with a low load and the resistance is increased by a set amount (usually 20 watts for women and 30 watts for men) every three minutes. A blood sample is taken at the end of each interval and analyzed in a tester. The test is continued until the athlete cannot hold a predetermined cadence. Time, power and blood lactate levels are plotted on a graph and the corresponding values where the line def lects at 4 mmol/ L is considered lactate threshold and threshold power.
The field test can be conducted on a stationary trainer or outside on a f lat road. Care should be taken to make sure conditions are the same
from test to test. If outdoors, there are environmental factors to be aware of; avoid wind, hills or stop signs. Ensure that the test falls in the athlete’s workout cycle at the same time. For example, athletes should aim to make the three days leading up to the test as easy – allowing athletes to be fresh.
As with any test effort, begin by warming up easily for 20 minutes then do a series of four, one-minute build intervals with two minutes recovery after each. Then do a five-minute time trial effort followed by 10 minutes easy. Now you are ready to go for the best average effort for 20 minutes, a maximal steady state effort that is uncomfortable, but manageable; anything above it is unsustainable and results in an abrupt drop off, avoid sprinting to the finish. To determine ftp take the average power for the test and subtract five per cent from this value. This is not quite as scientific as blood values, but with regular tests it is accurate. It is important to repeat either of these tests at regular intervals to stay up to date with improvements as the rider gets stronger.
Using Power Zones to Improve Performance
Every athlete is different, there is no one prescription to improving performance. For newer athletes coming from a sedentary background, oftentimes just getting out and riding is going to impact fitness the most. Gradually increasing mileage over a number of months in the recovery and endurance zones will improve cardiovascular fitness without overly stressing the heart. By staying below Zone 2 ( 75 per cent of ftp), the typical age group Ironman power output, athletes will improve bike stamina and be able to ride longer at a given heart rate.
Getting faster or increasing power is another matter for a seasoned racer. Studies have shown that repeated work at or close to ftp provide the highest fitness benefits. However, maximal efforts for every workout are not physiologically possible. One needs to balance recovery, strength and speed, muscular and cardiovascular over the week. There are a number of workouts that take advantage of the power meter. Strength set: An effort between three and twenty minutes with a cadence of 60 rpm at 85 to 90 per cent ftp at low heart rate, followed by 50 per cent time of interval easy spin ( less than 55 per cent ftp) ( Zone 1) between intervals. One mistake with using a power meter is to always strive for the highest achievable number. The goal for this particular workout is to stress the muscular system by applying a lot of pressure on the pedals. Threshold set: Short efforts of three to eight minutes with a cadence of 90 to 95 rpm at 105 per cent ftp ( Zone 4 to 5), followed by an equal time of recovery spin ( Zone 1) between efforts. This interval improves lactate threshold and cardiovascular fitness as one is working right at that upper limit. When performing this workout based on power, heart rate gradually rises such that the first interval will seem easier than the rest. By the last interval, the heart will be working at maximum capacity as a result of carrying the load from the earlier intervals. Threshold Endurance set (training for half distance races): three hour ride with intervals of 90 to 95 per cent ftp ( low to high Zone 4) (20 minutes Zone 1 recovery in between). This is a way to include higher than race effort in a longer workout. Of course these are only the bike workouts for a triathlon training program, swims and runs need to be accommodated. Be sure to include a run off the bike at regular intervals. Following a prescribed plan using a power meter allows one to precisely dial in their efforts and know exactly where improvements are being made. LifeSport senior coach Dan Smith has been involved with multisport for more than 15 years. Visit LifeSportCoaching.com