Without doubt, one of the most effective ways for triathletes to build fitness and speed is interval training. It’s a proven method that intersperses intervals of high-intensity exercise with short periods of rest.
Most swimmers use intervals in their training as a matter of course. Swimming a straight 2km in the pool is pretty boring. But split it up into say 4 x 400m and 4 x 100m and not only does time fly, but the work quality will almost certainly rise too.
Meanwhile, the rapid rise in bike computer technology use means that structured interval training on the bike is easier and more interesting than it’s ever been. But perhaps even more importantly, the risk of injury during high-intensity training in these two disciplines is relatively low. This is in stark contrast to running, where increased impact shock, combined with any biomechanical imbalances you might have, makes high-intensity run training a far riskier proposition.
Bike for run speed
Although the muscle recruitment patterns are different there’s quite a lot of overlap in the muscles used during cycling and running, which poses the question of whether interval training on the bike could enhance run speed? If so, bike intervals could be a valuable tool for injury-prone triathletes who want to improve run performance without the increased injury risk.
A group of British and Australian scientists (Etxebarria et al, 2013) have been studying the effects of two types of bike-based high-intensity interval training (HIT) on triathlon-specific cycling and running performance.
Fourteen trained male triathletes completed a maximal incremental test to measure their aerobic fitness, 16 x 20sec cycle sprints to measure their power and a 1hr tri-specific bike ride(at an average power output of 65% maximum power – simulating the relative intensity observed during Olympic-distance triathlon racing), followed immediately by a 5km run time-trial to measure tri-specific running performance.
After this ‘baseline’ test, the triathletes commenced an interval programme, training twice a week for three weeks, and were split into one of two groups:
- Short intervals (9-11 x 10, 20 and 40sec efforts at near maximum).
- Long intervals (6-8 x 5min efforts at 80% of the triathletes’ maximum oxygen uptake – in other words, fairly hard).
When the triathletes were retested after three weeks, both groups had increased their aerobic power by around 7% and both groups saw gains in power during the sprint test of around 10.5%.
What was fascinating, however, was that only the long-distance intervals had a truly significant effect on 5km run times, reducing it, on average, by around 1:04mins. Although there was a drop in 5km times after short intervals, it wasn’t large enough to be considered statistically significant.
Previous research using mathematical modelling suggests that cross-transfer training effects do occur between cycling training and run performance in elite triathletes, but that swimming training is unlikely to benefit either running or cycling.
That’s not surprising given the minimal muscle overlap between swimming and cycling/running. What this new study shows is how those benefits can be achieved. Despite the undisputed fitness benefits of short, high-intensity intervals, if you want to use cycling intervals to help your running performance in a sprint-distance triathlon, long intervals are what you need.
- To boost your 5km run performance in three weeks without performing running intervals, try using long cycling intervals
- Advanced triathletes should train twice a week, performing 6 x 5min efforts at 80% VO2max with 1min recovery between efforts. Build this to 7 x 5min efforts in week two and eight efforts in week three
- Less accomplished triathletes should begin with 4 x 5min efforts performed just once a week, building to six efforts as fitness increases
- Always ensure that you take a rest or easy day before and after your interval days
(Main image: Jonny Gawler)
For lots more advice on how to improve your performance head to our Training section