Anyone who has ever competed in a triathlon or duathlon knows the horrendous feeling of heaviness in the quads as you leave the bike rack and enter the run.
Your free-flowing running gait, which was the hallmark of your style when you ran fresh, is reduced to nothing more than a pathetic shuffle as you struggle to maintain contact with those with whom three minutes earlier you were riding shoulder-to-shoulder.
Take heart: there is hope. By undertaking a couple of practices and incorporating them into your normal training regimen, you can improve your running off the bike.
The Heavy-Leg Syndrome
Let's consider why heavy-leg syndrome occurs in the first place. Basically, there are two physiological reasons why your legs are reduced to sides of beef as you exit the bike-to-run transition:
To begin, when you cycle, a vast majority of your blood is directed to your quads. You experience what physiologists term a vasodilatory effect to the blood vessels and tiny capillaries servicing these muscles. As a result, you get a "pooling" or welling-up of blood in this region that remains when you exit T2 and then attempt to run. Therefore, heavy quads persist until blood is redirected to the muscles more directly involved in running (e.g., the hamstrings and calves).
The second reason has to do with neural innervation patterns. In plain-speak, when you ride hard for any significant period, your brain sends messages down your neural pathways telling your leg muscles to "pedal circles." Then, in a split second, you tell your legs they need to support your body weight and run. By asking them to perform a task completely unlike what you've been doing previously, you are not giving your body a proper chance to respond.
Still, as evidenced by the Simon Lessing's and Greg Welch's of this world, it is possible to adapt the body to perform under this duress. The question, of course, is how?
As you progress through a solid triathlon-training program for a few months, your body will naturally adapt to this demand, and running off the bike will become progressively easier. But there are methods you can incorporate into both your training and racing that will have you cruising out of the bike-to-run transition and regaining your land legs a lot sooner.
In Training
During the base phase of your training, incorporate at least one "brick" session into your weekly training. By definition, a brick session means a moderately long ride followed immediately with a moderately long run—preferably mid-week. This will force your legs to get used to firing the appropriate neural pathways and shunting blood from previously active to previously inactive muscles a lot quicker, without the pressure of competition.
As you start to get closer to competition, your brick session can be replaced by a "transition" session. Normally this session would combine all three triathlon disciplines in sequence, or in a mixed format, and you would work at the threshold of race-pace in all three disciplines for short periods (i.e., three to five minutes).
Treat the transitions as you would in a race, recover, and repeat the entire process another two to three times. Once again, you're getting your body used to the rigors of competition and teaching it to shunt blood and to fire appropriate neural pathways even quicker than was required during the earlier brick sessions.
Additionally, as competition looms closer, each time you get off your bike, go for a short run, even if it is only 800 meters, and treat it as you would a transition—go out hard until you find your rhythm and then turn around and jog home.
Finally, many observers of multisport have rightly labeled triathletes as "strength" runners who tend to muscle their way through the run as opposed to purist track runners who are termed "rhythm" runners and appear to float along on the track with a metronome's precision.
Obviously, there are exceptions to this rule, and anyone who has ever seen the likes Heather Fuhr or Luc Van Lierde in full flight off the bike will probably argue the point. But on the whole, these are exceptions rather than the rule. Consequently, because triathlon-style running is generally strength-orientated, you've got to become a strong runner, and that means hitting the hills.
Hill running requires you to use your quads more than running on flat surfaces, and the lifting motion of running uphill uses your quads and gluteals in a manner which is much more akin to cycling than running along the flat. This will result in a cross-training effect on your leg muscles and will benefit your cycling and running as well as your transition from one discipline to the other.
In Competition
In a smartly executed triathlon, your run starts well before you hit the bike-to-run transition. With about five to eight minutes of the bike portion remaining, start thinking "run" and prepare for it appropriately.
First, get out of the saddle in a slightly bigger gear and ride a couple of hundred meters standing up. This will alter your muscle firing patterns to make them more akin to running; it will also stretch your running muscles and start redirecting blood to the appropriate muscles.
Next, sit back down and put your bike into a smaller gear and spin your legs over, rather than cranking big gears all the way into the transition.
Finally, start stretching your "running muscles" (i.e., hamstrings, calves and lower back) on the bike as you head to the transition. This will help to ensure that they are looser, more supple and ready for the change of disciplines.
In the final analysis, there's simply no alternative to training, practice and competition. In other words, the longer you're involved in multisport, the easier running off the bike will become. But you can compress the learning curve if you incorporate some of the training and tactics discussed above into your preparation.