Some advice on increasing pedaling efficiency with platform pedals
So I'm a long time bicycle commuter, started about 15 years ago when I was in abject poverty and had no other choice. I knew nothing about bikes, but picked up a cheapo old mountain bike at a garage sale. I started huffing and puffing my way to work and back every day. Soon, I was no longer so poor but the biking stuck.
Wasn't until a few years later when I got into cycling as a recreational activity. I got a nice road bike with clipless pedals and boy what a difference! My daily commuter still has platform pedals though, I can't be bothered with wearing those shoes to work...
But, after thousands of miles being clipped in, and riding on rollers, some of that new technique has spilled over to the way I ride on platform pedals.
When I first started riding bikes, the way I thought about pedaling was to repeatedly push straight downwards on the pedal. Turns out, this is inefficient and only uses a few of your leg muscles. The most efficient technique is to engage many more muscles while pushing down AND pulling upwards in a fluid circular motion so that both legs are always working.
Unfortunately, since your feet are not attached to platform pedals, it's awfully hard to pull upwards on them! HOWEVER, you can do the next best thing, which is to PUSH forwards at the top of the stroke and PULL backwards at the bottom of the stroke, in a fluid motion. You can do this by finding shoes or boots with tread that kind of "lock in" to the platform pedal, so that your foot can't easily slide forward or back. Then, with each stroke, you PUSH forwards and backwards on the pedal in a fluid circular motion. You'll really start to feel your hamstrings engaging and your whole leg working. You'll be moving faster with much less effort.
Bottom line, you'll make it to work a lot faster!