Does running with a jumper (i.e. causing yourself to sweat more during a workout) increase the effect of a workout?

If the answer is no, then what does running in a jumper do? I've read it doesn't help you to loose weight (because you're loosing water rather than fat), and you've got to be careful you don't dehydrate yourself... so does it do anything positive, or should I stick to shorts and t-shirt?

I used to run in shorts and t-shirt, but I've switched to joggers and sweatshirt because it feels harder, and I assumed it was doing more good for me (because I can feel my body working harder running the same distance).

(I guess "effect of a workout" is ambiguous, so to add some context for my case: My intended effects of running are to keep building my stamina, improving my fitness and keep my body toned.)

4 Answers 4


If you're preparing yourself for exertion in a hot environment, wearing more layers will help condition your body and make it easier. For general fitness, though, it has a nominal effect.

  • Well the guy who I gave the accepted answer to seems to have deleted his answer... so let's try accepting another one :P.
    – Matt
    Commented Jun 28, 2011 at 10:21

You'll start out warmer, and you'll warm up quicker. If you're doing an early morning run when it's still chilly and there's dew out, you'd want to wear a jumper. If you're starting a run a bit later when the sun is already out and it's more nippy than chilly, or even straight up warm, not so much benefit.

I don't like spending extra time warming up to do whatever the core activity is, so I like to wear layers to start just for that. It's more efficient, and allows me to spend less time doing stuff I find boring.

Aside from the benefits of a good warmup (less risk of injury), I couldn't say whether there's any other benefit to it.


Layering clothing is a smart idea if you live in cooler climates, or where the weather may change suddenly [A].

then what does running in a jumper [sweater] do?

In my opinion, it is a throwback to the fashion from the movie Rocky. Although I like Christopher's idea of heat conditioning [B].

A - I live in Denver, CO. We can get some very severe weather changes. Also, with the altitude and humidity here, it is possible to get 50°F (28°C) temperature swings during the day.
B - Summer highs (here) are frequently over 100°F (38°C) for extended periods. During heat waves, the night time lows are rarely 20°F (11°C) cooler.

  • Guess I need to go rent Rocky out and take a look :P. Thanks for the answer. Wish I could accept 3 answers :( :P.
    – Matt
    Commented Jun 23, 2011 at 10:02
  • I hadn't considered the need for buffering. Can you pass through a significant elevation/temperature change during a normal training session? I've done it during an all day ride heading from the mountains down into Golden, CO. But not during a 45-minute exercise session. Commented Jun 23, 2011 at 12:02
  • @Christopher, not during a "normal" session. However, there have been a few days where a front blows in over the mountain and what started as a nice sunny day to go biking/walking became a rainstorm before I made it back home. And the temp swings are nowhere near as bad as when I worked in Conifer (4000' higher in altitude than Denver yields a 22°F drop just due to altitude difference [6.5°C/km or 5.4°F/1000 feet], but, hey, they got snow last week) while living in Denver (officially at 5280 feet above sea level).
    – Tangurena
    Commented Jun 23, 2011 at 16:12

I'm a regular 5k runner and I run 5+ times every week. I used to run with shorts and a shirt and I saw results in conditioning the body within 2 weeks (of course with a strict diet). After 2 weeks you will not see much results and eventually the running pace will come to you with ease.

I then tried running with jumper and track pants the following 2 weeks. The body found it more challenging and a stronger workout than running with just shorts and a shirt. The body difference was more toned than ever. However, after 2 weeks your body will adapt to that as well and you will go through that with ease.

Now I still run 5k a week but with weighted training of 2kg. I feel every run I do now is exhausting and more challenging than ever but the body toning is unbelievable. My whole body is so toned with low body fat percentage. Fitness is on another level.

My advice is that you have to know your body and what your body needs, but the end result is spectacular. Good luck!

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