Reader Olivia Chia asks: "Is cross-training effective in improving or maintaining running fitness? I have personally witnessed the benefits of keeping my workout routine varied with aerobic classes like bodypump/combat, occasional yoga and high intensity training. I find that I am able to run longer distances and clock better timings for my races despite running less than what I used to in the past."

Cross-training refers to a training routine whereby athletes engage in other sports apart from their primary discipline to achieve some sort of training effect.

From the perspective of a runner, if the question is, "Can I replace running training with other types of exercise?", then the answer is both "yes" and "no", depending on the individual's goals.

YES - BY PREVENTING INJURIES

As running consists of repeated movement and exerts tremendous stress on a specific group of muscles and joints, it is essential that this group of muscles and joints are allowed to rest occasionally.

By replacing some of your runs with other forms of exercise which activate different parts of the body, those muscles and joints which are worked the hardest during runs can be rested.

This may help to prevent over-usage of joints, muscles and ligaments, and allow a runner to stay injury-free.

I personally experienced a much lower injury rate when I trained for and competed in triathlons between 2005 and 2008, before switching over to marathon running. This may very well be due to my training hours being split among three different sports.

YES - BY COMPLEMENTING RUNNING

By replacing an easy run with an easy bike ride, you achieve the same objective of putting in some easy comfortable aerobic work.

But did you know that performing an aerobic exercise in a different form brings about a multitude of other benefits?

For example, cycling on a stationary bike requires you to activate your core muscles, while swimming requires you to focus on the regulation of your breathing - both skills are applicable to running.

Even yoga, which is generally not considered an aerobic sport but places an emphasis on stretching and building flexibility, is beneficial to runners as flexibility helps prevent injuries from occurring during vigorous exercise.

In essence, every sport that generates some carry-over benefit can assist to build on your running performance.

YES - BY MAINTAINING FITNESS WHILE INJURED

If you are injured, cross-training allows you to maintain your fitness as you continue to work on those parts of your body which are unaffected by such injuries.

This has been the greatest impetus for me to engage in cross-training. In 2011, I suffered from plantar fasciitis (pain at the heel) which required a prolonged break from running. During my recovery period, I turned to spinning (cycling on a stationary bike) to maintain my fitness.

However, I would caution that even with intensive cross-training, it may be difficult to maintain your full level of running fitness.

While I managed to retain a degree of fitness by replacing my daily runs with spinning sessions instead, I did require a few months to get back up to speed when I eventually returned to running.

NO - TO EACH HIS OWN

Sometimes, the best way to become a better runner is to run more. Everyone has his own sweet spot - the number of kilometres one can run in a week without injuries. When every kilometre counts towards hitting that sweet spot, it simply does not make sense to sacrifice running for cross-training.

Elite runners typically aim to first hit that magical number, and then add on another few hours of cross-training, strictly as a supplement.

In Olivia's case, I am not surprised that adding variety to her exercise regimen has enhanced her running times. Utilising the same energy systems while strengthening other parts of the body has allowed her to run better.

However, she may need to replace some of her cross-training sessions with running instead when she finds that her running times are starting to plateau.

However, as everyone is built differently, I would advise you to experiment with different training stimulus and see what works best.

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