Training with Power

Why Train with Power

As we are dedicated to keeping our coaching and training methods and practices as current as possible, we are able to offer a power meter rental service to coaching clients. Why do you need a power meter to train I hear you ask? Well, when training with power you are able to see the actual work that your body is doing in watts, rather than watching how your body is responding to the demands of the training as is the case with heart rate. Heart rate will vary dependant upon temperature, altitude, hydration and so forth. This heart rate variation will be apparent when viewed as a relation of heart rate and power. When training in hot conditions power will be lower when compared with a given heart rate compared to cool conditions.

Also when interval training anaerobically above the lactic threshold, using heart rate as your intensity guide, you would see a gradual drop in power as this type of training causes "cardiac creep" which is the gradual rising of heart rate at a fixed intensity, so you would actually be doing less work as the session goes on. The picture above shows how heart rate (Red crosses) rises although the intensity/power output (Green line) remains constant.

Training Applications

The uses of power meters within cycling is growing at a great rate with new methods and software for interpreting the data becoming more readily available, along with a large number of sport scientists lecturing on the subject and hosting coaching workshops. The power meter alone is of little use and can be a problem on the club run when every man and his dog wants to know what power your doing rather than concentrating on the road. It's the analysis of the data that will enable coaches and sport scientists to improve an athlete's performance.

Basic descriptions of some of the most useful analysis tools are as follows;

Quadrant Analysis and Power Distribution

Of all the data analysis tools available I find this tool one of the most useful for highlighting a fundamental area of cycle training that may in the past have been picked up only by a well trained eye. The quadrant analysis breaks down the power into force and pedal velocity and plots each set of data as a scatter plot.

The graph above shows blue (25 mile TT) and red (muscular endurance training) data points. When training it is important to generate the desired power output that will be required in a specific event, but what is sometimes neglected is what cadence or rate of muscle contraction is required for the event. For example mountain bike power climbing up very short steep technical off road sections as seen in the 2006 Commonwealth Games course is usually tackled with very high power and low cadence (Low muscle velocity), whereas tempo climbs such long European mountain stages are ridden with a high power at a high cadence (High muscle velocity). This Graph enables me to see that the intervals in this riders training ride (Red markers) were done using a slightly lower cadence and force that was used during the event. This information can be fed back to the rider and incorporated into the next training plan.

Functional Threshold Power

The functional threshold power is very similar to the laboratory assessed lactic threshold 2 which is described as a non linear rise in lactic threshold greater than 1 mmol/L during an incremental exercise test, or in lay terms, the highest intensity that can be maintained for a long time - usually about 1 hour.

Above this threshold there is an increased reliance on non-mitochondrial ATP turnover, resulting in fatigue and a reduction in power output. Functional threshold power can be used to see if the lab-based lactic threshold 2 occurs at the same power output when the rider is in a real world racing situation. This functional threshold for this 25 mile time trial is seen as the sharp drop off on the right hand side of the power histogram (Green) corresponding to 260 watts.

SRM Race analysis

This diagram shows the SRM analysis of a whole race. There are 6 training zones from recovery to anaerobic energy systems on the X-axis marked with time and % indications. You can see how much time was spent in each of the phases.

Almost the whole duration of this 25 mile time trial was ridden in the very highest aerobic threshold zone (Top of Zone 4) with little time spent in any of the lower aerobic zones. This curve shows clearly the importance of having a good aerobic power capacity and muscular endurance that is as high as possible in order to maintain the high sustainable power required for this event. Long interval training is very helpful here to build that muscular endurance on a sound aerobic base. Different events over different terrain will require very different physiological demands that need to be considered in the rider's preparation.