Endurance sports all have one thing in common irrespective of their origin. They aim to push your body to complete depletion, that is exhaust your muscles and work your cardio system beyond what you might have thought you are capable of. So when it comes to training for an endurance event it seems that putting in the hard miles will pay off in the end. Personally my race calendar involves several endurance runs, from 50 miles to 100 miles then ultimately a whopping 153 miles later this summer.
Getting miles into my legs has been paramount, but there are literally only so many miles you can do in a week before the quality of your running drops severely. To train consistently well you have to train smart, for me this means alternating the types and distance of runs that I do. Longer slower runs become very important as they aren't as high impact on your leg muscles as the shorter fartlek sessions.
Recently though I have been finding that cross training, that is to say training in a different discipline from running has been helping my overall fitness and leg strength. To supplement my run training I have been spending hours on the bike turning the legs over without generating too much resistance as so not to work them too hard but to work consistently in a certain heart rate zone.
Cycling obviously has a lot less impact and with the help of a heart rate monitor you can spend time working in a comfortable heart rate zone that is slightly more akin to your race heart race without punishing the legs too much. Coupling some good miles on the bike on days where the run work has been tougher is a great way to encourage your body to continue working under stressed conditions without over loading the resistance work going through your legs.
To give you an example here is an idea of how one of my weeks looks:
Monday: 2 mile warm up (130 heart rate). 8 mile fartlek session (heart rate up to 80% max), slow hour bike session (heart rate 120-130).
Tuesday: 4 mile warm up. 12 mile casual run (140 heart rate). Hour bike session (120-130 heart rate).
Thursday: 2 mile warm up, 5 mile fartlek, 1:30-2 hour bike session.
Friday: 4 mile warm up and 12 mile run. Optional hour on the bike.
Saturday: Long run day 20+ miles
Sunday: 6-8 easy miles and 1:30 hours on the bike.
If like me running is your main goal then make sure you prioritise your running miles and feel free to bypass a day on the bike in favour of being road ready the next day for a running session. However if you can fit in time on the bike I think you'll find that your body will thank you for it once you come to line up and race. Any queries or help with preparing a training program please feel free to contact me on firstname.lastname@example.org