'Cross-training' - attempting to improve your performance in your prime sport by practising a separate activity - was very popular for a time during the 1980s and now seems ready to make a second big splash in the athletic world. Several recent studies have shown, for example, that runners can completely preserve their performance capacities during time periods when they totally abstain from running simply by carrying out alternative activities such as cycling, aquarunning or stair climbing. Up until now, however, no published study had linked cross training with IMPROVED running performances during a race.

That cross-training research drought is now at an end. At the University of Toledo in the United States, scientists recently asked 10 well-trained runners who averaged 30-35 miles of weekly running to add three bicycle workouts per week to their existing schedules over a six-week time span. The additional cycling sessions were simple. On Mondays, the runners carried out five five-minute intervals on exercise cycles, with heart rates at 95-100 per cent of maximal during the intervals, which were always followed by five-minute recoveries. On Wednesdays, the athletes pedaled continuously for 50 minutes with heart rates at around 80 per cent of maximal, and on Fridays, the runners added three 150-second cycling intervals and six 75-second intervals at close to maximal intensity, with rest intervals again equal in duration to the work periods.

Augmenting the athletes' regular running work-outs with the cycling sessions may sound pretty tough, but the added workouts didn't do horrible things to the runners' endocrine or immune systems, and there was little sign of overtraining. Most importantly, the extra sessions produced some physiological and performance bonuses. After six weeks, perceived effort during strenuous running was lower, ie, the runners felt that difficult speeds were easier to sustain. In addition, the runners' 5K times improved by almost 30 seconds, from 18:16 to 17:48. The trio of weekly cycling workouts had produced faster running performances!

Most interestingly, the 5K gains achieved by the runners who added cycling training were the same as those attained by another group of 10 runners who instead of cycling conducted a trio of comparable running workouts each week on the track. In other words, adding extra running training wasn't any better than adding some similar cycling sessions in terms of producing faster 5Ks. Over the long run, in fact, the cycling might be better since it usually produces less leg-muscle trauma than running.

This it seems that runners can learn a valuable lesson. Running performances can be improved by jumping on a bike several times a week. For various reasons, however, it's doubtful that cyclists can improve their cycling performances by lacing on their running shoes. Triathletes should bear this in mind when they map out their weekly training schedules; a cycling workout will generally have a broader impact on fitness than a running session.