Cross training is a fancy way of saying mixing up your training. For instance if your a runner you could swap a run for a swim or a bike ride, and hey presto you are cross training.
Fans of cross training argue that it gives the body a rest from the same movements associated with whatever athletic activity you are pursuing. For instance swimming will take impact off your joints and work your upper body as well as your lower.
When someone asks me if they should cross train I usually agree, but warn about neglecting your chosen discipline. I would also ask how much weekly training you are already doing? If its pretty low then cross train by all means but do not swap it for your main discipline.
Lets say 'Susan' wants to cross train and is running 4 times a week for a 10km road race. She performs a track day a long run and two easy runs. She wants to swap one of her days for a bike ride which she enjoys. I would argue that a bike ride could be added not swapped for a run. A gentle ride on a rest day will aid recovery by getting tired muscles working, and flushing waste products out with increased blood flow. The extra cardio will also strengthen her heart.
But lets say Susan says she really doesn't have any time to spare. She want to swap a run session for a bike ride. Which one should she pick? Again I would advise her not to swap if she wants to hit her target time in her 10k, but if she is adamant then swap for a recovery run. Swapping for a hard session like intervals or her long run will de-rail her training.
Training is specific, that is to say if I want to improve at swimming I have to swim. If I want to improve at running I must run. Both are aerobic based activities and both will have a slight cross over, both will strengthen my heart and my circulation.
In a study a group of researchers took 15 men and put them through a swimming programme for 10 weeks. The swims were tough and in the range of 85-95% of maximum heart rate. When they tested the subjects in the pool they found that their VO2 max had improved by 11.5% and their swim time to exhaustion had improved by 34%.
The researchers then tested the subjects on a treadmill. Their VO2 max had only improved by 1.5% when measured on a treadmill! The run to exhaustion had improved by 4.6%.
This a perfect example of how training in one discipline does not carry over to another. Muscles must be overloaded and done so in a specific way to elicit an improvement. Little gain is to be had by 'getting your cardio' by cross training.
So don't cross train then? Well no. I believe cross training does have its place. If you are just training for general fitness I would urge you to try to exercise in as many ways as humanly possible, if you are training for performance in a certain sport you have to be more careful. Here are my recommendations for cross training and how to fit it in.
1. Don't automatically think cardio. If you are running/cycling/swimming most days you probably don't need more cardio. What you need is to address muscle imbalances and guard against overuse injuries. These are best fixed with strength and conditioning exercises or some form of movement that is far removed from running, think yoga, climbing, gymnastics etc. These don't need to replace a session but can easily be added in at the end of sessions or by doubling up a day. Just make sure your not draining your energy bank for your big sessions in the week.
2. If you do use another form of cardio use it for recovery. If you do feel like you would like to switch up your training then do it on a recovery day and don't go hard. A gentle swim/walk/cycle can help the recovery process.
3. Make sure your training is already diverse. If your running are you running on different surfaces, different gradients, speeds, distances. If you answer no then make sure you try to vary your training to guard against injury. There's a big difference between mountain biking and road cycling, just as there is between trail running and road running.
Lastly please don't take that I am against cross training from this post. If your just training for health and the fun of it all, go wild. Don't pigeon hole yourself, there are so many rewarding activities out there. If you have a target race or goal though, you have to be specific in your training, discipline and some sacrifices will have to be made if you want to achieve your best.
I do hope you take something from this post and please e-mail with any questions.