Indoor Training Part 2

Continuing from where my last post left off, I thought it would be beneficial to add a post about some basic workout principles, and the variety of different workouts that could be done on the bike.

First off, I just want to say that this post is not going to completely exhaust all the various workouts and all their respective physiological benefits; there is an entire book I would recommend if your really interested called Training and Racing with a Power Meter by Hunter and Coogan which is 350 pages of training principles, and workouts (Coogan who is the one behind the power zones that so many elites, amateurs, and weekend warriors use today). I also want to note that just like in running where you have some coaches calling your half marathon pace "T" pace, others call it Tempo Pace, with cycling there are a number of different power training zone schemas that have been proposed, the most popular being Andrew Coogan's, and Joe Friel's from the Triathlon Training Bible book. Personally I go by Coogan's formula since it is more similar to what I would use in running in terms of the terminology, and the terminology used for some like myself who has a exercise science background makes the most sense to me.

What are these zones and how do I set them up? I'll take you through the easy process (well easy in the sense that it doesn't take very long) of how to get started with them. So you've bought your smart trainer after reading my last post and learning about all the different things you can do with the trainer. Your pedalling along on Zwift and in the top left corner you see you power number says 200W. You say something like, "Oh this is so cool, look over here [parent] or [significant other] I'm pedalling at 200W." To what the reply is always, "Cool [sarcastically], is that good?" "Umm, uh, umm, I think so." What you really need to do to maximize the impact of your indoor training and training and racing performance in general is first to perform a Functional Threshold Power Test or an FTP test. "Oh no, a test, is it hard?" Well...hate to kind of calm your excitement from your new trainer for a bit, but an FTP is essentially the closest thing to hell on earth, other than the world as we know it with Trump as President. It is out and out a sufferfest, and no matter how many you've done you never really get over the butterfly feeling in your stomach, sweaty palms, fear, and the memories of being hunched over your bike over a puddle of sweat and tears weeping like a baby when your getting ready for your next test. "So why should I need to do it?" An FTP test helps you to structure your training, get the most out of every workout, to pace yourself in long races so you don't blow up 10 miles to the finish, to track improvement over time and make adjustments as necessary, and to add the experience to your growing mental training folder** to reference it in times of need.

**While all elite athletes are extremely skilled at being able to essentially sever the lines of communication between there screaming/burning legs and their minds, all elite athletes and any endurance athlete in general will get to some point in a race when those signals coming in from their body are too much to ignore anymore. That is why it pays off to build a mental folder of all your training experiences and emotions to reference when you need to, to be able to tell (convince) yourself that everything is okay because we have been here before. Remember when on that training ride or run we felt this same thing, and it ended up being okay, so keep going. Basically when out training take notes constantly of your feelings and aches and pains, so that when out racing you have a huge folder of experiences to draw from. Just for some real world application, I'll give an example of how I did this. I've mentioned this many times before but in 2013 in my lead up to Scotiabank Marathon, I designed my own little Race Series called the Running on the Sun Series. It was mid-July and Toronto was experiencing the hottest heat wave in its history (and still is to this day). Daily temps w/ humidity were in the 40s. I decided during that four day stretch to put in at that time the biggest block of run training I had done - 152km in 4 days (38km/day), and was running outside around mid-day and then another run a little bit later without taking water during the runs (Disclaimer: I am not recommending this). I was returning from runs emaciated from the sweat loss and dehydration. But it meant every run for the rest of the summer I cruised along like I was now completely immune to the heat, and did well at Scotiabank because I had the memory of those July days out there baking in the heat to look back to and use as a comparator. Going down Queen Street I remember literally having a conversation with myself in my head saying, "You remember those 400/800s that day in July when it was 43, how much pain I was in and how much I wanted to stop, this is nothing, so keep going and stop complaining." 

Anyways that was a long winded way of saying that FTP tests, in addition to serving as a benchmark and a reference value for all your training, build mental toughness. So what is it and how do you do it? A FTP test is a 20 minute max power test, that helps to predict your maximum estimated 1 hour power. Why do a 20 minute power test to predict 1 hour power, and not just a 1 hour power test. Well because a 20 minute test can be repeated more regularly (every 6-8 weeks), whereas a 1 hour long test will take too long to recover from, which will impact your other training, and will require a more substantial taper to go into the test fresh. A 20 minute test on the other hand takes maybe a 2 day taper of going a little easier on the bike, and maybe one day easy afterwards. However, for myself personally, I don't perform well on an FTP test if i've rested too much on the bike leading into the test. Usually, a couple days out I like to do a little pre-test of a few 5-6 minuters at my goal power for the test to get my mind wrapped around the necessary power. Some people on the other hand will like to have 2-3 days of super easy riding to be as fresh as possible. For the test to be the most accurate and give you a true picture to your level, the software TrainerRoad (which I discussed in my last post) has I believe the best test method. It starts with a 30 minute all-encompassing warmup. The warmup includes three short 1 minute efforts which are all about leg-speed (cadence) and not too concerned with power. This helps to further ramp up the system, and warm your legs sufficiently prior to the test. Then after these efforts, TrainerRoad includes a 5 minute all-out effort just prior to the 20 min test. This 5 minute effort is the reason why I think that TrainerRoad's FTP test is the most accurate. While a 5 minute all-out effort may sound counter-productive just prior to going all-out for 20 minutes, I believe it is beneficial in a number of ways. First it further enhances the warmup, and more importantly it helps to burn off any anaerobic contribution to the test. The test is truly about the aerobic system's capabilities, so you need to eliminate that anaerobic contribution which could help you start very hard for the first minute and over-inflate the test results. For the test itself you would like to have the effort be as constant as possible start to finish, not starting too quick and having your power fall off a cliff the last few minutes, and conversely you don't want to start too conservatively, and then in the last 2-3 minutes be hammering a much higher power. For instance not starting out at 300 W, and then with 3 minutes to go ripping at 450W - that would indicate you started way to slow. At the end of the test you should be having to try with all your might to maintain the power, you shouldn't have anything left for a sprint to the finish. A perfect test therefore would be you start at say 340 W and the power doesn't drift outside of a few watts from 340 so maybe keeping the power between 337-343. If you have TrainingPeaks the variability index for the 20 minutes should be very low. Below is a picture from TrainingPeaks of my last test:

 The highlighted area is the 20 minute segment, and the variability index for my test was 1.00 meaning the average power and normalized were the same - meaning a perfectly consistent test (not to sound to arrogant). So that's the test. 20 minutes flat out. In my experience I usually find 11-13 minutes into the test to be the hardest. I just find its when fatigue is really starting to kick in, and at the same time you still have 7-9 minutes left which mentally can seem very daunting. But you can make it, just find different things to focus on. For me, I get through the first half repeating in my head stay calm, be patient, and keep it smooth. In the second half, I usually resort to trying to focus on my pedalstroke. So envisioning a perfect smooth circle, kicking my toes over the top, and pulling my heels across the bottom. If times get really tough, I have even got through tests by counting in my head 10-15 pedalstrokes for my left leg, then 10-15 for my right, and repeating that a couple times, and before you know it, you've knocked another minute down. After you finish, and have stopped sulking, and your breathing calms down you will get the result, say with that previous example you managed to keep 340W. Remember this is a 20 minute test used to predict your 1 hour max power, therefore your 20 minute power will be slightly higher than the 1 hour power, how much: 5%. So you take that 340W and multiply it by 0.95 and you would get 323 W, or TrainerRoad will do this for you, and that is your FTP. Now, besides 323W now being your FTP number with which you will set up your power zones (which I will explain in just a second), is that number any good? Well to help normalize the playing field and see where you stack up to the pros, you can take that power number and divide it by your weight in kilograms to give your W/kg value. And then Coogan, who analyzed many riders from world class to untrained cyclists, put together a great table showing where the W/kg for 5 second power to FTP lies for various ability levels (shown below).

Now finally the Zones 

So you have you FTP number now you can take that number and develop your training zones, or let TrainingPeaks or Strava or really any Premium online training software do that for you. With Coogan's formula he describes 7 different training zones: 

1. Active Recovery (<55% FTP): can keep this power all day long, or commonly used during recovery between intervals. 
2. Endurance (56-75% FTP): Can still keep this pace all day long for the most part. The upper end of this range at 75% FTP will definitely increase breathing rate, and would require some concentration to maintain, but you should still be able to hold a conversation reasonably well. 

--before I get to the other zones just to say a brief word about active recovery rides, and endurance rides. Based on my previous posts in the past, you probably could guess that I'm not a huge fan of these super long monotonous low intensity type workouts. Even when I was only running I wasn't a fan of the classic LSD run (long slow distance) which was popularized in the 1970s during the running boom, and still a high percentage of runners incorporate LSD runs as a weekly staple in their marathon build. Even though the fact is they aren't that effective physiologically, and for elite runners especially those who already have a huge mileage base and aerobic base there are pretty much a waste of time. For years East African runners have been doing long hard runs instead, and since Abebe Bikila won gold in the Olympics in Rome 1960, the East Africans have dominated the sport. The way I've always looked at it is if I'm out here running for 2.5 hours or riding for 4 hours I may as well get some good quality work in. Essentially, I like to focus on quality, rather than slow, monotonous quantity. I think my aerobic base is pretty substantial, so I don't think riding for 5 hours in zone 1 is going to do much for me. 

3. Tempo (76-90%): this is kind of a middle zone. You can maintain this intensity for a long period of time, but it does require a fair amount of concentration to maintain especially when your in the upper end of this zone (88% is very different then 76%). For the long course triathletes out there your Tempo Power is a  realistic range to be within for the entire bike leg. For 70.3 distance the general guideline is between 80-85% of FTP, and for full ironman 70-75% depending on experience. Beginners could be conservative and make their goal the lower end of those ranges, and then see how well they are able to run off the bike. For some people there may be able to run well off higher for 70.3s say 85-90%. Because this type of power is quite sustainable, tempo "intervals" are usually very long. I say intervals with quotations because for me a tempo ride might be anywhere from 1.5 to 2.5 hours long of straight continuous power at say 80% FTP, so I don't really consider them true intervals. But you could make these tempo type workouts slightly more enjoyable and make the time pass quicker by having say 10-15 minute blocks of power at various percentages all within the tempo zone. So for example you could do a workout of 60 minutes continuous tempo riding with 15 minutes at 80%, 15 minutes 83%, 15 minutes 85%, 15 minutes 80%. Or even staying within that tempo zone of power but breaking the time up with cadence variations. So for instance 15 minutes at normal cadence, 15 minutes 3-5 RPM higher than normal cadence, 15 minutes 10 RPM lower than normal cadence, and then the final 15 minutes at whichever of the two (higher or lower) was more challenging. Besides the aerobic benefits of tempo zone riding, it helps you to get accustomed to producing a fair amount of power for a prolonged period of time. You can use tempo rides closer to the race to mimic what the goal race power will feel like, or to fine tune what percentage of that zone you are able to run well off of in brick training. I like to do a lot of my brick runs off tempo power workouts. I think it more closely replicates the feeling in the race since that will be the power I'm targeting, compared to doing a brick run off of say 10x3 minute VO2 max intervals. If the goal of the workout is to hurt, sure go ahead and run off some insanely difficult bike workouts, but if the goal of the workout is to simulate what you can expect to feel on race day (and add those memories to your mental training folder) than brick runs off tempo power is the way to go in my opinion. Really with any swim/bike/run workout it is crucial that before the workout you are able to answer the simple question of what is the goal/purpose of this workout (how is this going to benefit me on race day).

4. Lactate Threshold (91-105% FTP): Work done in this zone is intense. You can't maintain conversation anymore, and it requires full concentration to maintain the target power. Efforts can still be relatively long anywhere from 8-30 minutes (if on the low end of the zone - more on this is just a bit**). The goal of intervals done at or just above the lactate threshold is pretty self-explanatory: increase lactate threshold. The power at lactate threshold is probably the most important determinant of performance for endurance cycling. Going just above your threshold (101-105%) is going to help push your FTP (threshold) higher and therefore you will become faster. Also by riding only slightly above your FTP you'll become both physically and mentally accustomed to a workload just beyond your current capabilities. With threshold riding my favourite workout has to be over-unders. Over-unders can be anywhere from 6-15 minutes long and alternate between going from about 95% FTP to 105% (essentially going just over, and then "recovering" just under your lactate threshold). So you can ride for say 2 minutes at 95% FTP, then 1 minute at 105%, then back to 2 minutes at 95%, and then back to 105% for one minute and so fourth. This type of workout has so many benefits. Firstly, physiologically you improve at how quickly you are able to clear lactate, and "ride off the burn" while still being at quite a high intensity. Also mentally, over-unders make you into a tougher rider, since it's that first 20 seconds or so after the over period at 105% when you just want to back all the way off, except you need to work through that very uncomfortable feeling in your legs while still being at a very high power.

**Sweet Spot - this additional zone is really like zone 3.5. The power in this zone is between 88-92%, so between upper end Tempo, and low end threshold. Even though Coogan didn't formally include this zone in his 7, it may be one of the more beneficial zones. Essentially, you are able to get the same physiological and psychological effects of a threshold workout but because the intensity is just ever so slightly less you can do longer and more repetitions of intervals. And you can do these workouts more regularly since they require less recovery then true lactate threshold workouts like the over-under I explained. With sweet spot workouts you can make intervals 15, 20, 30 minutes or even longer. You can do workouts like 3x20 minutes at 90% or 2x30minutes at 90%, and you will get huge benefits increasing your aerobic capacity and FTP. 

5. VO2 max (106-120%): the last zone I will talk about in detail is the classic and sometimes dreaded VO2 max zone, which as the name suggests is for the purpose of increasing your VO2 max, or maximal aerobic capabilities - increase stroke volume and cardiac output, muscle capillarization, hypertrophy of slow twitch fibres, increased plasma volume, etc. Intervals can be anywhere from 3-8 minutes in length, but only the most experienced would be able to stay in this zone for 8 minutes. In this zone you will have severe leg discomfort, hard breathing, and fatigue, and the time accumulated in this zone would rarely be more than 20-30 minutes. Also, although VO2 max workouts are extremely effective and important physiologically they can only be done so often and with a good recovery before and afterwards (not on repeated days). Physiologically speaking one could actually only sustain VO2 max for 8-9 minutes therefore your not going to be doing something like 10x9 minutes intervals at VO2 max. A good effective VO2 max workout could be something like 4x5 minutes, or 5x4 minutes at 108% FTP. Something though that I did want to touch on with VO2 max workouts is how to properly design the workout when it comes to the rest between intervals. From rest it takes our bodies approximately 2 minutes to get to VO2 max, therefore when you design a workout it will not be true VO2 max workout if you do say 10x2 minutes with 5 minutes recovery between each. The 5 minutes of recovery will be enough for you to get back down to baseline, and the 2 minutes will not be long enough to ramp your aerobic system up to its maximum. That being said could a VO2 max workout use 2 minute intervals. Absolutely, however, the rest between each needs to be short enough that you are unable to get back down to baseline. So you could do that same 10x2minutes but only 1 minute recovery between each, and then since you are not able aerobically to get back down to baseline you will be starting from a higher intensity at the start of the next interval and therefore able to actually reach VO2 max. Again going back to what I said previously, you need to ask yourself what is the purpose of the workout. If the goal of the workout is just to repeatedly hold a power which lies within your VO2 max zone for 1 minute at a time then sure do 10x1 minute at that power with a full 10 minutes of recovery in between each, but understand that you will not be actually touching your maximal aerobic capabilities. For that the interval needs to be about 3 minutes long to ramp up to your aerobic capacity, or that same short interval of 1-2 minutes can be used but with a very short recoveries in between each.

6. Anaerobic Capacity (greater than 121% FTP): short intervals 30s to 3 minutes to increase anaerobic (sprint) power - which is why I'm not going to go into detail on them since then aren't really important for long course triathletes

7. Neuromuscular power: super short 5-15 second out of the saddle sprints not designed to get after any metabolic gains, but more to just increase musculoskeletal power (again not big advantage for long course triathlon).

So there you have it all the training zone explained with some workout examples. In the next post, which will be the final part 3 of indoor training, I will put it all together to help you come up with a good structured training plan for your bike training. I hope you found this helpful, I compiled all this information from about 15 different sources the main one's being Andrew Coogan and Hunter Allen's Book: Training with Power, Joe Friel's Training Bible, TrainerRoad, and Jack Daniel's Running Formula 3rd Edition, along with my own exercise science background, and experiences. 

Thoughts on Indoor Training

Indoor Training

Years ago you could maybe count on one hand how many people you knew who trained either exclusively or did the majority of their training, whether it was running or cycling, indoors. Nowadays it seems that everyone is converting to indoor training, or at least incorporating it into their regular training regimen in some way. It used to be that indoor training was pretty much reserved for those of us living in cold climates to get into some quality training runs in on the treadmill, or for cyclists trying to stay in good shape through the winter by spending long hours on the bike while getting to watch some tv at the same time (a point I'll touch on later). Now however, we are seeing many athletes, including myself, not just hold a spot in our training regimen to be indoors throughout the winter, but also year-round. I think the shift in the training methods stems from a couple different factors.

Firstly, indoor training has become more fun and engaging. It used to be that when the snow started to come down and cover the streets, cyclists would either stop training until the spring, or would grab there bikes and take them out into the garage or the dark dungeon of a basement fix their bike to the trainer, and go at it suffering in absolute boredom for hours on end. Now we have all sorts of different gadgets and software tools to help the time fly by and actually use this "offseason" time to make huge gains on the bike. We have smart trainers like the Wahoo Kickr (http://www.wahoofitness.com?acc=a532400ed62e772b9dc0b8 6f46e583ff) which can do a number of fun and interesting things. The trainer can simulate climbs up to 20%, simulate downhills since the flywheel is so heavy (5kg) if you stop pedalling the wheel keeps spinning giving an incredibly realistic road feel, and it is compatible with numerous different online platforms like Zwift and TrainerRoad which can help you become a faster, stronger cyclist. Zwift (http://zwift.com/) is an interactive online world where you bike around an island and your smart trainer will automatically simulate all the climbs and downhills to making it incredibly engaging and rewarding. Basically what I mean by simulates climbs and downhills, for those who don't know how the trainer or Zwift works, is that in Zwift when your

Riding on Zwift - normally in the top left corner
are you stats like Time, Power, Heart rate, cadence
hill gradient, speed, etc. 

character on the screen gets to a hill the trainer automatically adjusts the resistance making it harder to pedal and the amount of resistance depends on the gradient of the hill. If your going downhill, the trainer lowers the resistance accordingly, and you can gear up to blast it down the hill. In terms of it being interactive, everyone who has Zwift is riding on the same Island so you have thousands of cyclists able to interact with you as you play. And it is not just merely everyone is separate doing their own thing on the island, the software has been developed so that when you are behind another cyclist you benefit from the effects of drafting, and their are always races or group rides that you can join (your speed is determined by the terrain your on and then a combination of your power (wattage) and body weight (W/kg)). The game is also linked into Strava so there are KOM's and segments where you can compare your best times to everyone around the world. It will be tough though to get some of those KOM's as there are many professional cyclists who use Zwift on a regular basis.

TrainerRoad (https://www.trainerroad.com/) on the other hand I find just as engaging as Zwift but a little more serious (I use both). Yes in Zwift races can be very intense, and they also now have workout mode where you can select from a number of workouts, but TrainerRoad is a training tool where you can either select a training plan that gives you daily workouts to complete or you can pick and choose workouts selectively without being in a plan, and as you complete the workouts instead of the screen being a character riding around a bright and beautiful island, on the screen is just a lot of graphs and numbers telling you heart rate, power, time left in interval, speed, overall time, power variability, etc. How TrainerRoad works is first you complete an FTP test, and then lets say in your plan you are to complete an interval workout of 5x10 minutes at 90% FTP w/ 3 minute recoveries at 50% FTP. If your FTP is 300W then the 90% is 270W and the 50% for the recoveries is 150W. In trainerRoad, there is something called Erg Mode which basically automatically sets the resistance on the trainer to keep your power at a certain number no matter what the cadence is, therefore you never have to change gears. What that means is you can spin at 60RPM and the trainer will boost up the resistance to keep the power at 270W and when you speed up the cadence to say 100RPM the trainer will lower the resistance slightly but still have enough to keep you at 270W. So basically during the interval you don't really have to think to much about what gear your in or keeping your cadence at a certain number to maintain your power, the trainer will do that for you. No matter what it will keep you at 270W unless of course is gets to hard and then you can't pedal anymore and need to stop. On the 50% or 150W recoveries the trainer will lower down the resistance automatically, and you recover at whatever cadence you like, again the trainer keeps you 150W regardless. In addition to having over 1000 different workouts to choose from, the training plans are extremely effective and there a numerous available to be specific to exactly what you training for from Sprint Triathlon to Full Ironman, short steep climbs for mountain biking, cyclocross, hilly grand fondos, criteriums, 40 k TT, etc. The plans are also nicely periodized into a base phase, build phase, and speciality phase.

In addition you can use these smart trainers to simulate exactly the race course you intend on racing to help you with those test sets prior to a race. You can do this by using online tools like Best Bike Split (https://bestbikesplit.com/). Basically here's what you do (it is quite brilliant):

1. Make an account on Best Bike Split 
2. Go to "My Bikes" and input all the information on your bike (the make, geometry, fit, components, wheels, hydration setup, etc) 
3. Go to "My Profile" input you FTP, max heart rate, experience, height, weight
4. Go to "My Courses" and search for the race course that you are doing, they have most, if not you could just create one; so for instance I can look up Wisconsin Ironman 70.3 
5. Then in "My Races" add the course, and the predicted weather conditions, and the tool will work out based on your FTP, riding position, weather, road surface, and the course profile the estimated time and your average and normalized power for that time. If you want a specific time you input that and the software will work out the power needed for all the segments on the course and give you all this information in a nice graph. For example for Wisconsin it may say for a 2:13 90k bike split up Observatory Hill I need to average 310 W, and then 250W on following downhill etc. 
6. Then now this is pretty brilliant, what you can do is two things with this information: either you can take their proposed power plan file for the course needed to achieve your goal time save it and load it into TrainerRoad where you can now essentially ride the course at your goal power indoors to prepare, or you can upload the power plan file to your garmin and during the race have your target power number for whatever segment of the route you are on live on the screen with your current power making sure you stay on power and can achieve your goal time. Essentially it will give up live power instructions during the race. 

Miami Prediction with new improved FTP, under this
Best Bike Split has the power for all the segments
the graph shows the power plan for the race. 

Now some of you may be wondering well how accurate really is Best Bike Split at predicting my time and the power needed to achieve that time for whatever the course is. Well the software was not developed by some triathlete or cyclist like myself just wanting a better way to be able to pace myself on the bike. Instead it was developed by a PhD Mathematician, Ryan Cooper, who came up with this super complicated algorithm late one night prior to a time trial in the Tour de France which correctly predicted something like the first 10 riders times, including Chris Froome and Tony Martin, to within seconds over a 36km stage. It has of course been refined and perfected since then so it is incredibly accurate. In Barrelman this year it predicted my bike split to within 12 seconds, and in Miami to within 22 seconds (when I had only estimated the temperature and wind speed 2 weeks prior, had I used the forecast from the day before it would have been bang on - but still 12 or 22 seconds over a 90km bike ride (and remember in Miami I had also took a wrong turn at one point which cost me some time) is pretty amazing).

So that was all my first reason for why indoor training is becoming more popular - lol sorry about that rambled on for quite a while there. The second reason why I think indoor training throughout the year is becoming more popular is because well quite frankly biking outside can be downright dangerous with all the idiot drivers out on the road. Not only do I not trust any driver out there enough to put my head down and blast it at 45 km/hr on a city street with traffic, but the fact is that with the insane level of development in the GTA and York Region there are very few places where you can go without encountering a traffic light every few hundred meters. Therefore, it is almost impossible to do effective workouts outside anyway. Think about it, your out there doing a VO2 max workout where you are really going to challenge your aerobic system by biking at 125% FTP for 3 minutes. The challenge is not hitting 125% FTP, that part of the workout is pretty easy, but the challenge really is maintaining 125% FTP over 3 minutes, 3 minutes where your heart rate is going to go up and up and up until getting close to your max heart rate. So your out there ripping through the first minute at 125% FTP and heart rate is steadily climbing, and boom, red light, you have to stop, heart rate drops back to resting, and that's pretty much the end of that interval. No point finishing out the other 2 minutes, the workout was supposed to be 3 minutes. 2 minutes at that wattage won't be enough time to get the aerobic system churning at full gas.

So to sum it up, indoor training is safer, more effective in my opinion, and becoming more and more interactive and engaging. For me, last year I did probably 98% of my riding indoors. However, having said that, I do think outdoor riding still has it's place. First off, I think it is important to still have some of that road feel outside in terms of being confident in your aero-tuck position, and also handling of the bike on turns and downhills (and being confident enough to be aggressive going downhill). On the trainer, you can sometimes get pretty lazy regarding your core activation since you don't need to balance the bike at all, it isn't moving anywhere fixed to the trainer. It was always funny last year when if I went for a long of a period of time without going outside, that first time outside, the first minute or so, you would feel a little wobbly on the bike. It would come back within a minute, but still wouldn't want to train 100% indoors and then arrive at the race without having been outside on the bike in months. Second, while I believe you are able to work on your aero-tuck position indoors, it still always feels slightly different outside. So go out once and a while and practice staying in your tuck for extended periods of time to get used to that feeling for race day. Third, bike skills like taking in your nutrition need to be practiced outside on the road. It is great on the trainer having your three or four bottles surrounding you well within reach, but outside it is different. If your like me and have a bottle up between your arms in the aerobars, and a bottle behind the saddle (the most aerodynamic spot hidden from the wind), you need to practice reaching behind you to grab that bottle. I didn't take my own advice in this case, as just before Miami I purchased a behind the seat mounted bottle, and was not able to get used to reaching behind me to grab that bottle in such a short period of time. The flexibility to do it and the balance required was just not something I had worked on and when I got to Miami, I was able to take the bottle out of the cage, but in the race I couldn't put it back in (it was a very tight fit with my bottle I was using + the bottle cage has 14 lbs of grip) so I had to just fill my front bottle with the rear one, and then toss the rear bottle (a 12.99$ bottle wasted; it was at the aid station so wasn't littering). Lastly, outdoor still has it place for extremely long rides. Yes I have done 4.5-5 hour rides on Zwift and TrainerRoad before inside. How? Takes a lot of mental fortitude, and an amazing music playlist. I think on some of those rides my Dad probably started to think the music was on random since I think I started with electronic dance/house music (my favourite training music), then changed to latin party anthems like Daddy Yankee, and Don Omar, then went to ACDC, then some old-school Blink-182, then some CCR, back to electric music, and so on. But seriously, I think it is possible to do very long rides inside, however, why not keep indoor rides slightly shorter, and more intense to get the most bang for your buck, and save the super long rides for outside where you can work on being in your aero position, find some new roads, and practice hydrating on the go. That brings me back to my point from earlier where you hear about people doing 5-6 hour long rides in front of the tv watching netflix. Personally I think my aerobic base is pretty darn good after years of pushing my body to the limit, so I really doubt spending 6 hours on the trainer watching Suits episodes where my heart rate doesn't go above 110 is really going to benefit me in any way. Indoors I like to keep my rides under 3 hours for long rides, but within those 3 hours there is a tonne of high intensity work. 

Some Final Tips to maximize your Indoor Training:

http://www.wahoofitness.com?acc=a532400ed62e772b9dc0b8 6f46e583ff
Go to Wahoo Fitness for more information on differen trainers,
they have the direct one shown here, and a cheaper but still
incredibly high-quality wheel-on model. 

1. Buy a good fan. Unlike when you are outside, inside the air around you is not moving, so you can overheat very quickly without a fan, and your performance will suffer.
2. Related to the first stay hydrated (and make note of your weight before and after rides to see how you are performing with your hydration) 
3. Invest in a decent sound system, and start compiling a good music playlist. 
4. Use a smart trainer like the Wahoo Kickr to be able to take advantage of all the online training tools available nowadays. 
5. Don't neglect your position on the bike. I like to always incorporate some drills to work on my position into my workouts. For example, lifting one hand off the handlebars and seeing to it that your body position doesn't change at all, holding that position for 30 seconds, and then switching hands. Or another could be making sure your "sit" bones are anchored to the wings of the saddle, and pelvis is not tilted forward. Indoors is also the perfect place to work of pedalling technique (kicking your toes over the top 10-2 o'clock position, and then pulling across the bottom 4-8 o'clock position). 
6. A safety tip from inside from someone who really knows it (trust me): When you are done the workout, do not linger, take the shorts off, shower and get on with the day. After a few hours sweating buckets in a pair of bike shorts, the chamois essentially becomes a petri dish for bacteria, fungus, and yeast to thrive (sorry this is so bluntly put but it needs to be said). Get the shorts off and shower, and do not, I repeat DO NOT, wear the same shorts twice. I am famous for talking too much (look at this post it was supposed to be short and sweet and here I am still writing). In elementary school and high school I spent pretty much everyday after school in the office because I was talking too much in class - many times where my parents had to be called in to the school and told by the teacher that "Frank just won't stop chatting to other students during the lesson." However, after I'm done a training session it is not the time to chat to people about how good of a workout it was (or bad), or when Tiger Woods is finally going to be healthy (come on man I'm rooting for you). Go upstairs and shower. How do I know what I'm talking about well I'll tell you, it's embarrassing but I'm open on this blog, last year in October I got an absolutely horrible infection in my groin area (from sweaty bike shorts) and it actually kept me from running for just short of a week, and when I did manage to get my run in it literally felt like I was running with shards of glass in my shorts. I also couldn't sleep at night for about two weeks because I was in so much pain and so damn itchy. Anyways, my point is don't linger finish the workout and move on. 
7. Finally, have fun. Indoor training as I think I've explained is a great way to not only stay in shape, but also improve your fitness during the winter and also year-round, so give it a try.

In my next post, I will talk about the variety of different bike workouts I like to do, and some tips on using heart rate data to it's fullest.