It depends on what your goals are? Are you going to race?
Short version: 4/8 time spent swimming Master's swim time 3/8 time biking and 1/8 time running with 1/8 time crossing training weights particular emphasis on strengthening knees 1/10 time stretching.
Ok...I know that adds up to more than one..yet proportions are what matters.
I give special Clydes tips below.
Important to remember is that recovering time for running is inherently longer Clydes as impact to body is exponential.
Cycling DEFINITELY helps running ESPECIALLY for clydesdales as it takes the stress off the joints. First consideration: How many hours a week do you that to train? I always believed in proportions a this is not affected by the number of hours...one week I could have more hours...next less...yet proportions can stay the same.
My personal experience: I was a fitness consultant who did Tris at the highest level (nationals and won every Clydesdale I entered back in early 80s) weighing 250lb(Football build) redesigning my body to 200-220lb 5% body fat. At my peak I was training 6-8 hours a day for over a year. 4 hrs/day for a few years. I say this to let you know that what I say comes from a great deal of experience of trial and error and reading everything I could on fitness(including latest medical journals)
Even if you have a great biomechanical running form, we can't escape that the force of each foot strike is exponentially greater by a power of 3(if I remember right...so 5lb more is 5x5x5=125lb strike force).
I am not sure if it translates exponentially at the same factor back up the body due to the vectors of strike...it is a glancing blow. I didn't read any articles back then on someone doing the physics of the strike force translated back up the body. Maybe current research shows something different.
In ultra distance training you are trading off many factors: How many hours do you have to train? Recovery time for the training you do(e.g running requires more recovery time)? How strong are your muscles supporting knees and rest of the body. My goal was to increase my aerobic capacity as much as possible with reducing recovery time as this would allow more intense training. One summer I did 12 Tris in 13 weeks.
So I joined a Master's swim team. Swimming can be one of the areas you can shave the most off your total time. Yet, once you have a clean stroke, get your open water skills and have specific training done to a certain level....the time returns on swimming diminish quickly versus time invested. Where swimming pays off long term is recovery time, increasing Max VO2 faster and with less toil on the body. Also this helped with my ability to process lactic acid when pushing redline in general YET you need to do sport specific training. Swimming also increases flexibility thus reducing injuries and allows spine to decompress from all the running.
In Tris the time it takes to do each event in order (greatest first) is : Run, Bike, Swim.
Yet the order of time training should be the opposite for Clydes unless you are going for an ultra personal best and will accept wear/tear on the body from that extra running training. Whatever race run distance is, you should have some runs going at least up to 1.25 times(not more than 2.0...diminishing returns) the race distance the 4-6 weeks prior. Then leading up to the race, you should be working on more speed/intensity vs long slow distance. If you have time, the max I would run(trade off ...the higher intensity workouts are harder on the knees and longer recovery time) is 2 interval workouts and one LSD each week. This allows for alternate day running with extra day after LSD.
Back then the thought was to do your high impact workouts earlier in the day and less impactful workouts in the evening. This would allow your body to decompress. My experience bared this out. On this subject I HIGHLY recommend going to a chiropractor. (I was totally against them when I was younger yet one saved my season in a week of treatment after 2 months of treatment by an Othropedic surgeon did nothing for my swimmer's shoulder. After 4 weeks of chiro, I NEVER had swimmer's shoulder again. Find a chiro that all the top local athletes go to...they will be more in tune with their bodies ...as Chiros vary greatly in adjustment ability/knowledge)
Back to specific training, regarding running the goal is to finish the race strong so you need LDL yet need to have speed so the intervals you use should be fairly long...even up to 1/10th race distance. Longer intervals will reduce recovery time...besides...you are not training to have a power kick at the end. Remember, your general aerobic workouts will come from the pool and bike.
With regards to biking I would say the same proportions of LDL versus interval work. Now, I trained in Louisiana which besides Texas is a Clyde's greatest friend. The highest mountain I ever climbed was a staggering 200 feet and that was a bridge!! If you have climbs in your race, you must train for them...this is where a good portion of your interval training should be done. As a clyde on a bike, we are like elephants running stadiums. This is where you can lose the most time. I remember when I did real hills/mountains for the first time....I bonked for months. Riders I could easily keep up with on the flats just blew past me like I was slug. Their time gains on the climbs far exceeded what I could gain back with power on the flats as air drag increases exponentially.
: I iced knees after every run as this helped reduce recovery time/ reduce long term negative effects. 20 minutes on/off with towel between skin/ice. I was careful not to fall asleep with ice on(set alarm) as one can cause nerve damage which can result in one not walking properly for life. I had it where I left it on my ankle as I fell asleep. Woke up after an hour to discover I couldn't move my ankle properly for hours.
is very important...it will reduce recovery time and prevent injuries.
Things that I didn't do that I would do now. I would try replacing some of my running with running in the pool with one of the vests made for that. I would even run with running shoe(clean, old pair) in the pool if pool director. Shoes would help protect the bones in the feet.
Get your running style video taped on a tread mill and analyzed to make sure you are getting the best shoe. Each shoe maker has different fits/styles in their shapes. But for my money, there is only one company that makes their shoes that can handle a clyde and that is Nike. I would always run with their max cushion shoe and my racing shoe would be a mid cushion shoe like the Pegasus. I may go lighter if it was a big race with no other races coming up knowing I was risking injury/longer recovery time vs faster finish time..
Weight training should focus more on lower body and core muscles as this builds the muscles that support knees/joints and abs/lower back excercises will help support spine. Leg work outs will help with the bike. I found leg extensions/curls better than squats (less stress on the knees and more closely resembled biking/running motion. Calf raises help with running and biking. I would do mine seated as this didn't put pressure on the spine.
With what v1k1ng1001
said regarding impact/nonimpact building tendon strength, bone density. This is very true. So in this regard, depending on the length of the tri, running should be incorporated in to training at least once a week. If the run portion of the tri is longer than 3 miles then you need to be more frequent. All of this depends on if one has a extensive running background where tendons strentghened/density increased. Tendons take much longer than muscles to strengthen(why you see sterod using body builder blow out tendons while weightlifting as the tendon strength has not developed in tandem with muscle strength) Bone density take longer.
By rule(trial and error) The longest race distance I would run would be 3 times my longest LDL run which I could/would consistently run. This would ONLY be done with great cross training. I could still run the entire race reasonably fast yet couldn't finish with speed as I didn't train at that distance. Also, my recovery time would be 2-3 times that for distances I had trained for.(1 day versus 3-4days) Now, this was done with a long running foundation over an extended time that allowed for tendons to strengthen and bone density to increase. Before applying this rule, I would think that one would need a 3 month running foundation minimum to reduce the chance of tendon/stress fracture issues. I would recommend that someone considering an accelerated running training program or a tri training schedule that was very light with running training to do a little research on how long tendon strength /bone density takes to develop.
hope this helps.