Is a passive heat session exactly what it sounds like? How warm does the bathwater need to be to see results?
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@Scott_Barrow - absolutely. There’s certanly a trait around “big day” mentality for the best riders I’ve worked with over the years. Not many riders can be at the very top of their game on the exact dates they want… MSR, Roubaix, Tour, Worlds… I think there’s an important psychological aspect that brings the best out of their physiology / performance. Super interesting.
@chasse_patateThe first thing is to figure out how hot the water is that comes out of your bathtub. Buy a good-quality thermometer, fill the tub, mix it well, and measure the temperature a few times at different locations. I did this without me in it the first time, and repeated it after 10-mins, 20-mins, and 30-mins.
How much temperature does it lose over time? Then you know whether you need to add more hot water to maintain the temperature.
As our core temperature is around 37-38°C, I aim for a few degrees above this to ensure the water is hotter than I am, and so the heat transfers to the body. Everyone’s heat tolerance is different, so you need to use your judgement at first.
Personally, I started at 39°C for my first few sessions, as it meant I could stay in the water a little longer (temperature x time = heat stress). As I adapt, I increased the temperature to 40°C.
I find 41°C (and above) a bit too hot, and I can’t tolerate it for too long. I prefer a lower temperature for longer, and I feel the effects are likely better too.
ALWAYS ERR ON THE SIDE OF CAUTION - SAFETY ALWAYS COMES FIRST.
It’s better to do less, safely, than put yourself at risk. Especially at first. Indeed, it feels like “just enough” is the best strategy. Heat training is an additional stress, and should be considered similarly to hard intervals (but with higher risks, due to thermal stress),
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What an opportunity! I’m 63 and generally ride with about a NP of 190-200. How can I achieve a 1000 watts/30 seconds such as MVDP did at Strade Bianchi? I’ll hang up and listen.
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Hi @Jonathan_Baker. I’d like to know why my HR keeps climbing when I signed up to a sweet spot session?
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Hey Jules.
This looks completely normal for exercise in the “heavy domain” (which would include sweetspot, if FTP is set correctly). In the easier “moderate domain” (below LT1 [or similar]) we’d expect less drift in HR (although there will be some, with time).
There are likely two causes:
- Progressive recruitment of less-efficient muscle fibres through the session, which require more O2 (via the blood) to maintain the same power output.
- Increases in core temperature prompt the redirection of some additional blood to the skin for cooling (while maintaining blood flow to the working muscles).
Both situations lead to an increase in heart rate.
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Thanks @Jonathan_Baker very interesting.
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You’re welcome, @Jules.
I have some time today to answer questions, feel free to fire them over. 
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I’ve been reading various sources about energy replenishment during exercise in terms of % of kjs expended. The numbers vary but seem to hover around taking in 50% of what you “spend”. What are your thoughts on this approach? Any suggestions on finding ones own percentage?
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Does trying to maintain a calorie deficit of 200-300/day blunt the adaptations from training?
I’ve been doing coached training now for 4 years, and for the last 2 I am finding ftp gains very hard to come by. I am gaining fitness in other ways like fatigue resistance, but seem to be stuck with minimal progress improving the numerator of the watts/kg metric. I am seemingly always trying to reduce the kg denominator, and am beginning to wonder if that’s to my own detriment.
42yrs old, 69kg, 10-12hrs/week, 290 to 305 in last 24 months.
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@Drew, this is a challenging one, as there are several “it depends” factors to consider. The primary one is around what your starting glycogen stores are at the start of exercise? If you’ve been carbohydrate-loading in the previous days, they’re likely high, and may be lower (without adequate refuelling) if there’s been a big training block during the last days.
Replacing 50% from a high starting point is likely a good strategy. Replacing 50% from a low starting point may be risky, as it may lead to critically low glycogen levels in the muscle and liver, which can impair performance.
My advice would be to make a rough estimate of the likely KJ expenditure for the session and the probable proportion of energy supplied from carbohydrates (that’s tricky without lab testing) to understand the potential needs. If the session is quite intense or long, it’s essential to eat a carbohydrate-dense meal before exercise and then consume something like a 50% replenishment rate during exercise. Eating enough pre- and during-exercise ensures adequate fuel for the session, and removes the feeling of wanting to “eat everything and anything in the fridge” when you get home.
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@Matthew_Bart, I consider a 2-300 calorie deficit to be reasonably small, but the length of time you’ve been at this deficit matters too. If it’s been weeks, maybe a low number of months, then it’s likely fine. If it’s been chronic, years and years, I’d be thinking a bit more about it.
It also matters where the deficit comes – have you been adequately fueling sessions, and the deficit has been off the bike? Or have you been eating more while off the bike and underfueling your training? Maintaining training quality is obviously very important. But we also need fuel for training and adaptation. I’m also assuming that the calorie deficit is from carbohydrates, rather than from protein or fats.
Personally, I eat more protein on low-training days and reduce carbs slightly. If it’s a hard training day, I increase carbohydrates and reduce protein slightly. So I’m adjusting macro types to suit training. I also vary the deficit, or not, based on daily training. I’ll match energy needs when I train more, and I’ll run a small deficit when training is reduced. However, in both cases, I ensure that there’s adequate fuel for the daily session and replenish the stores after training to facilitate adaptation.
There’s more to performance than FTP (watts per kg) as you allude to in your post. But if we focus on just that metric for a moment. My approach would be to focus on the power side of the equation most of the time, and for that, you do need (more) fuel so that you can maximise the training stimulus. It’s generally harder to increase power than it is to lose weight (if you have a plan and willpower). Then, when it matters, such as before a big event or race, I’d look to drop weight over a shorter period, to boost watts per kg.
Finally, I’d need to know more about your training to comment on that side of the equation. Maybe / probably that needs a tweak or two too. Send me a DM if you’d like to discuss it.
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Thank you! This is very good clarity.
Replacing 50% from a low starting point may be risky, as it may lead to critically low glycogen levels in the muscle and liver, which can impair performance.
By this do you mean a low glycogen starting point may warrant more than 50% replenishment?
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Are you able to weigh in on the high protein debate that has been discussed on another thread here? What do you think about the debate on protein fads and upping the high end amount unnecessarily and what do you recommended for athletes? Do you ever suggest lowering intake?
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@Ren_S, I try to avoid fads (and podcasts) and stick to the overall consensus from the research. For endurance athletes, that’s 1.2-1.6 g/kg per day, or thereabouts.
I don’t think about a tick box for each day in isolation. I think about an average intake over a longer period. I eat more protein on easier training days, and I switch some protein calories for carbohydrates on harder training days. But I tend to stay roughly within the recommendations.
I’ll find and read the other thread when I have a bit more time.
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@Drew - Yes, exactly that. I think I read somewhere that “exhaustion” from glycogen depletion occurs somewhere around 20-30% of “full” capacity, as we reserve some for critical organs, such as the brain. We don’t hit zero. So, if we start with, say, 70% already, and we replace 50% of that amount, we can be around 35% of “full” and at risk of impaired performance. I know that percentages of percentages can get a bit confusing, but I hope you can follow the thought process.
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In my experience
- consistency beats any implementation details (provided the plans are reasonable), and
- the less you ride, the more nailing intervals becomes important and the more pyramidal you tend to get.
Coasting is a fact of life when you are riding outdoors. Things like navigating intersections and traffic force you to stop pedaling at times. That’s why training indoors is more time-efficient (≠ better all around).
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@Max_Lein – I’d mostly agree. But I think there’s an equal triangle of importance between consistency, specificity, and overload. I think we need all three. But also, doing something is better than doing nothing.
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That’s what I meant when I wrote that the plans are reasonable. And, obviously, I implied they should be comparable, a 5-hour/week sweet spot plan is not comparable to a 12-hour polarized plan.
I like your agnostic approach. I have been combining polarized and sweet spot blocks in my training for several years. In my experience (N = 1), they lead to different adaptations, both good, but different. 
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