One of the most popular questions asked by people beginning a fitness campaign is which is best - cycling or running?
There's no simple answer, of course, as each sport has its own pros and cons.
Running requires little equipment other than decent running shoes and is arguably a much more agreeable pastime than cycling when the weather is foul.
It's also very efficient in terms of fitness gains per hour invested. However, cycling is still a great fitness builder and the smooth pedalling action is much easier on the joints, which means a much lower risk of injury.
Cycling is also a great way to get from A to B, making it excellent for commuting and for the environment. Then there's the undeniable thrill of moving along at speed under your own power.
But research by US scientists suggests that when the training volume increases, cyclists enjoy an additional advantage over runners.
In the study, scientists at the Appalachian State University in North Carolina compared the levels of exercise-induced muscle damage, soreness and inflammation in cyclists and runners who were asked to perform a three-day period of intensified training.
To do this, 13 trained long-distance runners and 22 trained cyclists were monitored for a period of 12 weeks.
During this period, the runners and cyclists continued with their normal training, but during the fifth week, subjects from both the groups went to the lab and ran or cycled for 2½ hours for three consecutive days, which represented a significant increase over their normal training volumes.
Both the runners and the cyclists exercised at 70 per cent of their maximum oxygen uptake (ie a moderate-intensity pace) and had blood samples taken before and after the three-day period to test for markers of muscle damage, inflammation and immunity.
The subjects also reported on the degree of delayed onset muscle soreness (DOMS) they experienced.
In a nutshell
When the scientists compared the two groups, it became very apparent that despite the identically increased workloads and durations, the runners' muscles had taken a big hit compared to those of the cyclists.
The markers of muscle damage were 133-404 per cent higher in the runners compared to the cyclists. The runners also had inflammation markers that were up to 256 per cent higher.
Moreover, the runners reported a level of DOMS that was 87 per cent higher than their cycling counterparts.
When it came to immune markers, both groups suffered a drop in immunity of about the same magnitude.
If you're a cyclist who includes a bit of running in your weekly programme, you'll probably already be aware that hard running is more likely to induce muscle soreness than the equivalent intensity of cycling.
What this study shows, however, is that even at moderate intensities, running causes far more muscle tissue breakdown and inflammation than does cycling - something that partly explains why endurance runners generally have much weaker and less powerful leg muscles than their cycling counterparts and why runners are more prone to injury.
Another implication is that when adding running into a cycling programme, you should keep the length of your runs relatively short in order to minimise muscle tissue breakdown and strength/power losses on the bike.
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