JasonD67

I've been riding for decades, but just recently got a Scosche heart rate monitor. Only ridden with it a 100 miles or so, but found something that really surprised me. When I ride inside on the trainer, my HR is 20-30 beats less than when I ride outside despite me riding just as hard (or so it feels). Inside, I stay in Zone 2 most of the time and have to work to get into Zone 3. Outside, I'm in Zone 3 most of the time and the slightest hill puts me into Zone 4.

Now, the only difference I can see (other than it being a different bike on the trainer) is the temperature. Outside it's been in the 40's (~5C to our more enlightened readers), while my trainer sits in my toasty house. Have others experienced a similar increase in HR in the cold? I guess that might explain why my speed and cadence is lower overall in the winter as my body is using so much more energy to stay warm, as measured by the increased heart rate.

rubiksoval

It's generally the opposite as higher temperatures raise the hr due to the body trying to cool itself.

You're probably simply riding a lot harder outside.

A power meter would tell the difference immediately.

Dean V

It isn't the temperature. It can just be harder to put the effort in on a trainer especially if you are not used to them.
It takes a certain kind of mental discipline.
If you had a power meter you would see that power on the trainer is down as well, corresponding with the lower heart rate.

Seattle Forrest

My heart rate is about what you'd expect for the effort skiing.

You don't actually work harder to stay warm while you exercise. Heat is a byproduct of all the watts you're making to move the bike down the road.

Carbonfiberboy 

It's called "arousal." That's absent indoors or at least usually. Really loud music is helpful as is having some goals and staying on the rollers or trainer for over an hour. Indoors, warm up for 15', do three 1.5' max efforts, then take it up into Z4. It's not that hard. Once you get it up there, you'll cruise right along. Try holding a cadence well over 90. If you don't need a towel on the floor to absorb all the sweat, you're dogging it. That's why folks are saying usually lower power indoors because of overheating. Two box fans and cycling glasses should be necessary.

The thing is that HR comes up with arousal. Hormonal releases are what drive HR up. That's easy to get outdoors, not so easy indoors until you figure out how to do it.

MoAlpha

TimothyH

This is very intersting. Thank you.


-Tim-

on the path

If your HRM doesn't have a chest strap my money says it's the inaccuracy of your device. Even chest straps can be wonky in the cold weather, but are generally much more accurate than the wrist bands.

Sy Reene

The Scosche isn't really a wristband.. more of an armband. They're pretty accurate and don't suffer dropouts from lack of sweat (more common in the cold) that the chest-based units can have. Anyway, if same HR monitor is used both indoors/outdoors, on a relative basis the OPs results are probably correct.
https://www.dcrainmaker.com/2014/05/...h-optical.html

Voodoo76

I think your perceived exertion inside is fooling you. You are simply riding harder outside, likely because you are cooler. Ride to the same HR inside and I'll bet you are overheating, causing a higher perceived exertion. Don't underestimate how much air flow you need inside even at Z2. Add more or bigger fans, to the point were there is no sweat dripping off you (it's evaporating)& see what happens.

canklecat

Could be stress, tension. I burn more energy outdoors because I'm alert to dangers from traffic and road conditions. And it takes more energy to ride on the chipseal and rough pavement common to some areas -- more weight on the legs to compensate for rough roads. Outdoor temperature usually isn't a factor for me. I just dress for the conditions.

I don't pay much attention to my heart rate outdoors -- occasionally I'll stop and check it but I don't wear a heart monitor. Indoors on the trainer I check my HR and BP when doing intervals.

But I do have to focus on breathing properly outdoors. In traffic and on rough roads when I'm riding fairly fast I'll tend to tense up and not breathe from the diaphragm.

I notice the traffic stress more after having been hit by a car last year. I really notice it on climbs. I expect to have trouble on climbs so I tense up the abdomen, breath from the chest, and feel tired sooner. Self-fulfilling failure.

When I focus on breathing properly from a relaxed diaphragm I do better on climbs. Helps to find a long enough challenging route away from traffic. We don't have any long serious climbs here but there are a few longish gradual grades and I'll pick a day with a significant headwind to practice -- like Saturday's 22-40 mph headwind.

AdrenaChrome9

I have noticed the same results.

eja_ bottecchia

JasonD67

Rode on the trainer again today thanks to today's rain...turning my biggest gear (53-13 on my old bike), 100+ cadence, sweating like a pig and barely cracked Z4. Maybe I need more fans or someone yelling at me, but I just can't seem to get my heartrate up indoors.

on the path

For what it's worth... I've been using chest strap based HR monitors for years. I bought a Scosche about 2 years ago. Wore it on my arm, as an armband. I used it on 1 ride. I found it to be inadequate for my needs. It seemed to be accurate at times but, as an example, I did a tough climb and rather than rising steadily it just jumped around a lot, up and down.

I have a fitness wristband that has an HR monitor. It works relatively well, for what it's worth, but again, inadequate for my cycling needs. As far as the Scosche that I used once, I returned it for a full refund. Not "highly accurate" as advertised. I'm sticking with my theory that the OP's issue is with his HRM.

MoAlpha

JasonD67

mordy111

I noticed the same. My avg HR is about 10-15 points higher in the cold (28-32f)

I've read that air density is much higher in cold weather so much more work to achieve same speeds which likely contributes to the higher avg HR. I don't have a power meter so I can't confirm, but I did a similar ride indoors and covered way more ground in less time.

​​​​​​​M

Trakhak

I used to think that until I read a Bicycle Guide magazine article in which the writer reported going out on an off-road ride with one of the first wearable heart rate monitors on the market. He did a long, high-speed, technical downhill run and checked his pulse rate as soon as he got to the bottom, expecting to see a sky-high number. It wasn't far above his resting rate. As the writer said, "So much for heart-pounding descents."

canklecat

I'd still suspect that expectations and experiences will influence measurable reactions to conditions -- HR and BP. If the writer enjoyed that downhill run and didn't experience fear or anxiety, it's likely he wouldn't show elevated HR and BP.

I enjoy riding fast on the road (I'm inexperienced off road). But I don't enjoy being hit by cars. So it's likely my HR and BP will vary on public roads depending on conditions and presence or absence of traffic. It wouldn't surprise me if my HR/BP were within normal range on a 40 mph downhill blast with no traffic in sight, and then spiked during a 15 mph approach to a busy intersection. But I'd need a monitor to test my theory, along with time codes related to video or voice notes to correlated HR/BP with external factors at that time.

These are personal and variable factors, so responses would vary. And it would get into subjective interpretations, probably lacking a statistically significant sampling group, etc.

I suggest it only as one possible factor to consider in trying to figure out why our HR/BP varies between indoor and outdoor sessions.

canklecat

Regarding the air density theory, I suspect that has less influence than wind resistance. Power meters, Strava software guesstimates and similar tools usually don't account for wind resistance, tailwind assistance or buffeting from cross winds. But those are real things with undeniable influences.

Saturday I took advantage of a 22-25 mph wind from the west to tackle a PR on a favorite 6 mile time trial segment. But to get to the head of that segment I had to ride an undulating 8 mile moderate climb into that 22 mph headwind. Gusts and swirling winds redirected by the open prairie terrain caused some buffeting so it was a challenge to hold a steady line. I was riding solo, not much traffic, so it wasn't too stressful. The slow slog into the headwind was worth the effort for the reward. That TT segment is a blast, like a roller coaster ride, especially with a tail wind.

Looking at Strava later, and comparing results for other cyclists I know who do use power meters, it's clear that the effects of wind are omitted from the data. Power meters and software guesstimates tell us we're churning 300-400 watts for the 12-15 minutes it takes to ride that 6 mile TT route, but only 60-100 watts for the 6-8 mile uphill ride into headwinds to get there? C'mon, that defies logic.

Most meters and software only consider our moving speed, distance and terrain. Not winds, air density, road conditions, etc. We know we're working hard to ride into the wind, especially uphill and/or on slow pavement -- stuff like striated concrete or chipseal. Figure 150 watts, minimum, even if we're loafing along, and probably closer to 200.

None of those factors exist with indoor trainer sessions.

MoAlpha

The mechanics of riding outdoors and on a conventional trainer feel different enough that I would not be surprised if muscle recruitment weren't lower indoorst. That would reduce the demand on the cardiorespiratory system at any subjective level of effort. Consider running in a straightjacket or something, which kept the upper body from muscles from moving properly.

As for the "arousal" hypothesis, I can't reject it out of hand, but I don't think the effects of arousal and exercise are likely to be linearly additive, especially balls to the wall.

Power data would go a long way toward answering this interesting question.

2manybikes

It's the cold. It's more work. Long rides in the cold tell you a lot. Especially if you've been doing it for 25+ years. It becomes obvious aiming for, but not always reaching, 100 miles when it's below freezing. It's a lot more work. Hydration is critical too. The cold drier air dries the sweat off a breathable jacket and you don't know your sweating, You don't feel sweaty. Once, going 50 miles with 1/2 a big bottle at 25f dehydrated me so much it put me the hospital. I knew I needed to drink and I did and I was fine. My blood pressure was down to 60/30 before I got my drinks.
The best part is how much stronger you feel when it warms up.

BengalCat

As others have said the cooler it is the lower your HR for the same power effort at any given temperature. (Also the cooler it is the quicker the HR recovery if you really push it and then back off or rest.) For me the older I get the greater the impact of temperature on my exercise HR.

rubiksoval

What exactly do you think a power meter is? If I put out 300 watts in a tailwind and go 30 mph, and I put out 300 watts into a headwind and go 20 mph, I'm still putting out 300 watts.

That's what the power meter is showing.