Occasional half-marathon distance

Question

I've been running for about six months and have done a few easy 15k runs lately. I find them too boring to be enjoyable, but otherwise not particularly challenging. However, I'd like to be able to do a longer run and have the confidence to know I can do it if I want to. Would it be practical to do an easy half marathon say once a month, but otherwise to restrict my runs to 10k (the distance I enjoy most).

I'm mostly running for weight loss, fitness and enjoyment, rather than performance (I'm not interested in racing, except an occasional park run), so I am primarily concerned about injury risk (I am in my mid 50s, no longer overweight and in reasonably good health) and any other potential disadvantages I might not be aware of.

I am running three times a week at the moment (total 25-30 km), but also go to the gym and swim regularly, so there isn't much scope for increasing the number of runs.

Updates (empirical testing of the answers ;o):

19/04/2023 - I've run my first half-marathon (2:16:43) without a real problem, I'll try it again next month and report back. Hopefully the lack of an answer (at time of writing) suggests that my plan isn't too daft!

23/05/2023 - Run second half-marathon (2:18:06,but trail rather than on track and lower average heart rate). Felt much easier than last time, no immediate problems.

06/06/2023 - 2:13:35 this time, again on trail, continuing to feel easier, no immediate problems.

03/07/2023 - 2:08:45 again on trail, no problems. Did the last km at almost my 5k "race" pace (5:02 per km), which suggests I had something in reserve ;o) Weight loss has stalled for a couple of months, but that is less important than it once was. VO2 max still increasing.

04/08/2023 There won't be an August half marathon, I've strained my Achilles tendon, but I don't think that was anything to do with the half marathons, I injured it while sprinting and I have historically had problems with the tendon involved.

14/09/2023 Achilles much better now (thanks for the advice @Andy !), ran a (heart rate reserve) zone 3 trail half-marathon this morning, not very quick (2:16), but I did a lot of walking and gardening yesterday so my legs were already tired from the start. Very tired at the end!

Answer 1

The way to go strongly depends on your goals.

As your main goals seem to be keeping yourself fit and maintaining weight, the main variables to look at should be adherence and mileage. Thus, running enough volume (30k sounds good) and a fashion that you enjoy and feel able to maintain (check) sounds like a very good idea.

If you would sprinkle one of your 10k runs with some fashion of interval training (eg. 1min at faster pace without heart rate going through the roof, 4 mins with normalisation of pace/heart rate), it would be even more efficient for training the cardiovascular system and add significant performance training effects not as a main goal but a simple outcome of how much your cardiovascular system improved its function.

Generally, a half-marathon here and there probably doesn't hurt (especially if you protect your joints with additional, progressive strength training in the gym), but it also does not really add much in terms of long-term training effect.

In the end, it is all about what you would like to achieve. And if you want to (be able to) run more, frequent interval training is preferable.

For the goals you explicitly stated, what you do and enjoy is perfectly good, though.

Answer 2

Running 3 times a week 10 km should provide enough mileage to be able to run half-marathon.

Doing your longest distance one a month is not much, but if you'll do your 10km workouts relatively fast (compared to half-marathon pace), you'll have less effort per km in your long run, which should make it feel easier at least first 15 km. You're doing other sports, so you should be fit enough.

It seems that trying to run faster workouts will be good for you, because you easily get bored by running. Faster pace is more 'action' and the whole workout takes less time.

Answer 3

I am 50 and struggling with the same problem as you, and have spent a bit of time researching this.

First here is the best info I have found on how to rehab.

Next for what I think I have found so far:

Whenever a tendon is subject to a sufficiently high tension it starts signalling for repair and strengthening (collagen synthesis) to take place. Unfortunately the signaling only occurs for the first 10 mins (1). This means that if a workout involving the tendon such as running takes much longer than 10 mins the activity may be a net loss, the tendon is more damaged than it will be repaired. Instead it would be better for the achilles tendon to run shorter but more often.

Failing this it should be important to trigger collagen synthesis by strength training often.

Heavy (<= 8 reps) slow resistance (HSR) training works.

Very light high rep ( > 15 reps) "pump" work before and after HSR may be beneficial to "pump" blood into the calf muscle and the achilles tendon.

(Overcoming) isometrics also works(2). They work the tendons but the muscles not so much and thereby cause less muscle soreness. Say you perform HSR 2 x a week. Then you should perform isometrics on some of the other days.

Isometrics can be implemented using a barbell (3) or standing in a door frame pushing up with the arms. To begin with a standard unloaded 1 leg isometric calf raise will be heavy enough, but I think it is key to keep going past the rehab period and keep pushing the strength of the achilles tendon upwards.

Strengthening the calf muscles also helps since the muscles and the tendons work together. A stronger muscle puts less stress on the tendon. It is important to train both the gastroc: standing calf raises and the soleus: seated calf raises.

The strength training mentioned above should performed often, but not so often that the calf muscle becomes tight, pulling on the achilles and causing pain. This is a delicate balance.

Tendons are visco elastic. When the force is constant (rate = dF/dt = 0) they have one linear stress-strain region. However when the force increases rapidly (rate >> 0) such as when jumping or running they should stiffen up (slope in linear stress-strain region increases)(7). This is a very good thing as it starts the deceleration when landing from a jump early instead of stretching out the tendon fully with little deceleration before at the end where the tendon may snap.

HSR does not train this important aspect of the tendons. This is why plyometrics is a key part of the rehab process as mentioned in the link at the top of this answer. Sadly most of the info on plyometrics is targeting young and athletic people and this conditions how we think about plyometrics. Everyone may benefit from plyometrics (4). The key is to start with easy plyometric exercises, practice these 2-3 a week with low volume each workout, and progressing to harder exercises very slowly and cautiously (5). Doing plyometrics only once a week is not recommended (6: 2mins 5 secs). You will overdo the volume. It is much safer to do 2 sets of 5 jumps 2-3 x a week than to do 6 sets of 5 jumps once a week! When doing a box jump the landing should be soft and barely audible. If not you must use a lower box! I do not think it is worth the risk for someone our age to perform hard plyometric exercises. Better stick to the easy ones.

Also it may be better to use plyometric exercises that mimics the running movement (8).

(1) Jumper’s Knee: Train Twice Daily

(2) Jumper’s Knee: Keith Baar Case Study

(3) Overcoming ISO Calf Raise

(4) Plyometrics for the Elderly Client

(5) How to Progress Plyometrics

(6) How I Turned My Achilles Tendon Into a SPRING Like a Gazelle!

(7) Tendon Biomechanics

(8) 2 Exercises for The Achilles: Build SPRING and Reduce Injuries

Answer 4

12 months of running half-marathons, 11 half marathons run, no injuries caused by long runs (but strained an Achilles sprinting, so no half marathon in August and none in December due to an unforeseen visit to A&E). So one data point confirming the existing answers were right. I'm running them much more slowly now (trying the "run slow to run fast" thing - but it isn't working at the moment), this months was 2:24:20. Would like to get my PR below 2 hours at some point, but no rush.

... didn't take that long - managed 1:55:31 on Monday. I was in heart rate reserve zone 4 for pretty much the whole run, but didn't feel too uncomfortable. Will go back to running them in zone 3 again now. Thanks again to the commenters for their helpful advice!