Most athletes have a 'base-building' period during their training year, during which their intensity of exercise is kept fairly moderate while their volume (number of minutes or miles per week of training) is gradually increased. The purpose of this base-building phase of training is usually considered to be an increase in overall aerobic capacity and a gradual strengthening of muscles and connective tissues.

While most athletes have such a base period, few are sure about exactly what to do after the base phase is over. In addition, many athletes are faced with a sudden need to get into competitive shape quickly after a base period is over, because they may suddenly decide to participate in an important competition on the near horizon. For such athletes, what is a good way to emerge from a base period rapidly, heightening fitness without significant risk of overtraining?

The four-week regime
South African scientists have the answer. At the University of Cape Town, researchers followed eight competitive cyclists who were coming out of a base phase of training, during which they had been exercising moderately at about 80 per cent of maximal heart rate (around 70% V02max). The cyclists were about 25 years of age, weighed 174 pounds, had been cycling for three to four years, and were averaging about 43 kilometres (26-27 miles) of riding per day (300 kilometres per week).

At the beginning of the study period, which lasted for 28 days, the cyclists trimmed their weekly training volume by about 15 per cent and began carrying out interval training twice a week. The interval workouts were simple, consisting of six to eight five-minute repetitions per workout, with short, one-minute recoveries between repetitions. The intensity for each work interval was set at 80 per cent of peak power output, eg, about 90 per cent of V02max (heart rate would have reached around 93 per cent of max near the end of each five-minute interval).

Thus, the 'base-period-emergence training' was kept very simple. Regular mileage was simply reduced by 15 per cent, and two interval workouts were added each week. Otherwise, training continued as before.

More speed, power and endurance
Did the 'emergence training' improve the cyclists' performances quickly? You said it! After the four weeks of emergence-interval training, the athletes' times on a 40-K time trial improved from 57.1 minutes to 55.9 minutes, a nice 2-per cent improvement.

But that wasn't all! Even though the interval training was not really super-high-intensity exertion, the cyclists' 'peak power output' (the maximal power their leg muscles could exert while riding the bicycle) rose by 3 per cent in 28 short days, and their ability to continue pedalling at an extremely high intensity soared by 22 per cent (from 59.3 to 72.5 seconds).

In addition, maximal aerobic capacity (V02max) rocketed upward by 4 per cent, and muscle 'buffering capacity' (the ability of muscle cells to tolerate rapid rises in lactic acid) advanced by a hefty 16 per cent. Although not actually measured by the researchers, blood volume probably also burgeoned in the Cape Town cyclists (blood volume usually 'perks up' in response to higher-intensity training). A spike in blood volume is a definite plus for endurance athletes, because it allows the cardiovascular system to do a better job of transporting enough blood to both the muscles and skin. Of course, the muscles need blood for the oxygen it contains; the skin requires hot blood to cool off the body.

An especially heartening feature of the Cape Town research was the fact that the cyclists not only boosted their peak power after carrying out the simple interval workouts but also aggrandized the per cent of maximal power which they could sustain during a rigorous, one- hour effort like a 40-K time trial. Before the emergence- interval training, in fact, the cyclists could only work at an average of 72 per cent of peak power during the 40K; after the intervals, they were able to cruise at 75 per cent of peak power, even though their peak power was quite a bit higher than before!