QUESTION: I have been riding on and off for about 35 years. I am 54 now. My problem is I frequently “bonk” after about an hour. It doesn’t seem to matter if I am doing moderate or higher intensity ride. I can do 20 miles flat riding at about 15 MPH, my heart rate stays above 150 the whole time, after about an hour I just run out of gas.
I drink Gatorade and eat small snacks every 30 minutes or so. Sometimes I find a second wind. Sometimes I just crawl (metaphorically) back to the car. I always recover quickly. About an hour after a ride my heart rate is 70 or so. My resting HR is about 60. What can I do or increase my endurance and be able to ride 75 plus miles without bonking. I have the right gears and my position on my bike is pretty good, I am not a newbie. Just trying to get to where I was 20 years ago. – Brian W
ANSWER: Do you have any issues with low blood sugar when you are not riding your bike, or when doing any other types of exercise like hiking or long walks?
Most cyclists should be able to complete a ride of up to an hour without necessarily needing any calories at all. So if you are experiencing any other types of low blood sugar issues off the bike, my first recommendation is to see your doctor and make sure you don’t have an underlying issue such as Type 2 diabetes or some other type of insulin resistance.
Assuming no underlying blood sugar issues, I might suggest a counterintuitive idea. Might it be possible that you are triggering the bonks by consuming particularly high carb, sugary drinks like Gatorade and snacks that your body is overcompensating and trying to get your blood sugar back down just as you are exercising, causing a bonk?
How about trying to eat solid, regular food (like a meal) a couple of hours before your ride so that your glycogen stores are topped off, and ride the first 45 minutes to an hour with just water and then begin fueling? Additionally, you might try switching to an energy bar with water instead of Gatorade, to prevent a blood sugar spike from the liquid calories that could be followed by a bonk.
Kevin Kolodziejski recently wrote a column about his experience bonking after a sugar spike from eating a more highly processed food than he was accustomed to eating before his ride.
Two other articles about fueling — one from a retailer that sells endurance nutrition products, and another one from a manufacturer that makes it — have some decent tips about fueling for a ride.
The Feed writes,
A few years ago, I was about to start a 130-mile ride down the coast of California as part of multi-day San Francisco to San Diego charity event. For many of the participants, this was a daunting athletic challenge. At the start –at 6 am I might add– I saw a number of people tear into and devour a Gel…
This is actually the moment that I decided that I needed to start The Feed. That I could share my knowledge and help people with how to use performance nutrition, like Gels and Chews to their advantage, not their detriment.
The folks I saw devouring the gels and chews were going to be in for a rough day. They were now spiking their sugar levels and there was no way they could now consume enough chews and gels, aka Quick Energy, to sustain themselves for the next 8 to 10 hours of riding. The result I predicted (and came true) was that they had a significant energy crash after the first few hours and really struggled to finish the ride.
And Hammerhead Nutrition writes,
Yes, the body needs your assistance in replenishing what it loses, but that donation must be in amounts that cooperate with normal body mechanisms, not in amounts that override them. Here’s an important fact to keep in mind: at an easy aerobic pace, the metabolic rate increases 1200-2000% over the sedentary state. As a result, the body goes into survival mode, where blood volume is routed to working muscles, fluids are used for evaporative cooling mechanisms, and oxygen is routed to the brain, heart, and other internal organisms. With all of this going on, your body isn’t terribly interested in handling large quantities of calories, fluids, and electrolytes; its priorities lie elsewhere.
Your body already knows it is unable to immediately replenish calories, fluids, and electrolytes at the same rate it uses/loses them, and it has the ability to effectively deal with this issue. That’s why we don’t recommend trying to replace hourly losses of calories, fluids, and electrolytes with loss amounts. Instead, we recommend smaller replenishment amounts that cooperate with normal body mechanisms.
When even the guys who make and sell endurance fuel are telling us this, there might be something to it.
Readers, what is your perspective on this? How have you overcome bonking issues?
Rob Tesar says
I suggest you check out the website “off.io..” It appears that you are relying too much on carbs for your energy needs. You need to switch your engine to burning primarily fat.
Vespa can give you a good start on that.
Rob Tesar says
Sorry, that should be “ofm.io.”
Road Bike Rider says
Rob, do you use this product? I’d never seen it before today. If so, how often are you using it? Most rides, just important rides?
I am 54, too. Agree on the carbs as a problem (a lot of good advice in there), but the real issue is you are trying to sustain 150bpm for more than an hour. If you want to go 2 hours, drop your HR to 140. More than that should be 120-130 or lower. I still ride very long (multiple 12 hour days and recently Everested) and I’m can sustain descent speed, but I can’t sustain a 150 HR for much more than an hour. It is just part of being 54. It isn’t a problem going hard, even to 165+ bpm at our age just don’t expect to sustain those higher HRs for as long. Taking on much more than 250 calories an hour will only make it worse.
Jim Langley says
Okay, these are going to sound like a really stupid questions since you’ve been cycling so long, Brian, but I’m going to ask anyway. The reason I’m asking is because I’ve run into this before and it’s not impossible that you might have an issue like this.
1. By any chance has your seatpost slipped down in your frame so that now your seat is way too low and it’s not efficient at all for you to pedal causing you to work much too hard?
2. Is something rubbing on your bike. For example a chainring can rub against the frame and you might never notice it but it will sap your energy greatly. I had a triathlete friend who had this happen and he rode on it for so long that it wore a hole through his chainstay. Brakes are common rubbers, too and not everyone would notice. Wheels, too, can rub though usually it’ll be the tire rubbing, which typically means a flat tire soon.
3. Are your tires underinflated? With the new trend to softer/lower pressures it’s very possible, even easy to go too low and if the tires are too soft you will use more energy.
I figure your bike is probably fine but wanted to suggest a few things just in case it’s not you it’s your bike,
Rob Tesar says
I do use Vespa, but only on longer rides (75+). I’ll scarf down a concentrated pack every couple hours. The people at Vespa also suggest adding in some “strategic” carbs when necessary—-you have to experiment to find out what works for you. They are not “anti-carb,” but they suggest that carb’s (things like gels and “energy” bars) should not be your main source of fuel. About the only thing I take before a ride is a Vespa packet mixed with water and some beet powder.
FWIW—-I have also tried ketone esters which are supposed to quickly get you into a fat-burning mode. Very expensive, though, so I have to be prudent on when and what amount I ingest.
Pete Hall says
I think you need to slow down and work on your fitness. At 54 years old, 80% of your max heart rate is 132 beats per minute. You are practically sprinting for one hour. Exercise below the 132 bpm, and slowly build up your fitness. I am impressed you can ride for an hour at that high of a heart rate. Just my two cents.
Brian Nystrom says
The old “220 minus your age” rule of thumb for calculating max heart rate really doesn’t work, especially for active athletic people. Max heart rate is very individual. For example, I’m 65 and my max HR is still 180 or so. Using the old formula would mean that 80% of my max would be 124, which is a very easy pace for me. I can ride for multiple hours averaging 145-150. I’m certainly nothing special, just an example of how there aren’t any hard and fast rules for max HR.
David Le Fevre says
The suggestion that you’re triggering your slump by consuming sugar fits what happens to me, though it seems to be hitting you harder that it hits me.
I’d noticed that after a café stop on our club rides, my legs would feel a bit jelly-like shortly afterwards, lasting for a few kilometres. When I mentioned it to a clubmate, he suggested that it was the quantity of sugar in my coffee giving me a sugar high, which was inevitably followed by a slump.
I don’t consume much sugar, but I take a lot in my (black) coffee in order to counteract the sweetness. I’m pretty sure that my clubmate’s diagnosis was accurate.
Let’s assume that what he says is an accurate explanation of what he is feeling (“My problem is I frequently “bonk” after about an hour.”), then there is most likely an underlining health issue. Under no normal circumstances should this happen. The human body should not become functionally depleted of glycogen in under an hour (the definition of a bonk). But without some kind of testing there is no way to be sure what is happening. A “bonk” is not just being tired – it’s the total emptying of the engine – it’s exercise induced hypoglycemia. Is that what is happening?
A doctor should evaluate this. This seems serious.
Anecdotal experience: I don’t mix hydration with caloric intake (Gatorade has about 130-cal/500g from fructose and glucose). There are plenty of hydration and mineral replenishment methods that are practically calorie free. Eat calories – leave drinking calories to emergencies. This helps to better control the type and quantity of calories and hydration. Experiment with the foods you eat on the bike to find what fuels best. I like real food (e.g. fig newtons, apple pie, jelly & cream cheese sandwiches) on long rides until I near exhaustion when I might resort to some gels or simple sugars (cola); gels are calories of last resort. On long rides (more than 90-minutes) I’ll try to replace about 200 calories per hour but this isn’t easy because overeating is worse than being a little hungry. 4 hour ride = 2400-cal burned and close to 800-cal consumed. Generally if I don’t go much over 5-hours, then a 30% replacement rate works fine.
Harald Portig says
Could it be that the bonking here has nothing to do with carbs and calories, but is a symptom of overheating. As I got older, I had similar problems with bonking, sometimes as early as 45 minutes into a ride (I am 80 years old now). I was usually sweating profusely, and when I got home my rectal temperature was high. On one ride in 2012 I measured 104ºF. I drank two glasses of ice water which helped me cool to 100.2ºF in 35 minutes. In 2015 I measured 103.2ºF after a ride. I noticed that over time the feeling of bonk occurred at lower temperatures. Nowadays it seems that if I keep my heart rate around the mid-130s I don’t bonk. I think that monitoring heart rate is almost as useful as monitoring temperature.