I used to routinely run about 35 minutes each day. This was interval style running with 30 second sprints every 7 minutes or so. I kept this up for about 2 years. My stamina increased greatly doing this, but I didn't loose any weight.

Recently, I've cut out the running and started to cycle to work, which is 20 mins each way, and in only 2 months I have lost heaps of weight.

Although I do do 5 mins more exercise on the bike, I would have thought that running would be a more intensive work out, what with supporting your own weight more and not coasting.

I'm just curious: is there any reason why cycling seems more effective for me?

2 Answers 2


Yes, it's called the principle of specificity (or specific adaptation to imposed demand, SAID), essentially, your body will adapt to demands placed upon it, so if you run in a certain way every day for 2 years, your body will be very well adapted to it and more efficient at doing it, greater efficiency means less work means less calories being burned.

Cycling to work, although a lower intensity workout, is something your body isn't used to, so it hasn't adapted to it, learned the most efficient way to do it, so it burning more energy.

A great example of this is opposite to your situation, but is when Lance Armstrong ran the New York marathon. His body was very well adapted for cycling and performed it with amazing efficiency, but when it came to running, the efficiency wasn't there.

  • So the more I ride to work, the more weight I will gain. Damn!
    – MeltingDog
    Commented Feb 10, 2017 at 3:16
  • @MeltingDog Think of it more as, the more you ride to word, over time, the less calories you'll burn doing it. I'm not entirely certain how these things work, but you could try mixing it up by changing the route, cycling in a different gear to make it easier or harder, stopping every 5 minutes to crack out a few sets of chin ups on a nearby tree, anything really ;) Slightly more seriously though, people are often only concerned with burning calories, there are a host of other benefits to this type of physical activity past simply burning off that Mars bar you snuck in yesterday afternoon :)
    – Dark Hippo
    Commented Feb 10, 2017 at 9:07
  • I tell my athletes "if you settle for mediocrity, it becomes you." As outlined by @Dark Hippo, your "settled" state is likely responsible. Your metabolic tax, for lack of a better word, completely changes when you change your demand system on different muscles. This was the Lance Armstrong example. One thing I'd add is you can do more with cycling than with running. You can have more variations in gears, explore anaerobic sprints, hit hard climbs in different gear ratios for totally different workouts on one same hill. This mixture will allow you to "not ever settle". Commented Feb 11, 2017 at 15:25
  • @ngườiSàigòn With cycling I tend to hit it pretty hard as much as I can. Strava helps with that, I like seeing how I can increase my average speed and beat records on segments. If I keep this up - striving to get faster and faster - will it help?
    – MeltingDog
    Commented Feb 12, 2017 at 22:50
  • So long as you are mindful of not settling and avoid plateauing, it should work. Using a heart monitor would give you a much better feedback. Remember, HR monitor don't just tell you how hard you work, it can also signal you when you are doing it wrong or withdrawing. When you want to track your body, use a HR monitor. When you want to track speed, techniques, use the cyclo-computer. Basically, use both. I used to do this on my rides to work, & also switched up the different routes every few days, which changed all the hills and sprints along the way. Commented Feb 19, 2017 at 4:12

The lower intensity of cycling could be promoting more fat burning vs. glucose burning from the high intensity running. LiveStrong

One of the main factors, aside from diet, that influences the ratio of fat burning to carb burning is exercise intensity. At low intensities your body will turn to fat for energy, but as you start to train harder, it will switch to burning more glycogen, notes Dr. Edward Coyle of the Gatorade Sports Science Institute.

You're also working out twice a day instead of once; that could be having an effect as well. Have you noticed a change in cravings or eating patterns? Do you think you're eating more, less, about the same?

  • Thanks for the response. I think I'm eating the same amount, but I am craving less.
    – MeltingDog
    Commented Feb 9, 2017 at 6:22

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