A Fitness & exercise forum. FitnessBanter.com

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » FitnessBanter.com forum » Fitness & Exercise » General
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

the physics of situps

Thread Tools Display Modes
Old November 14th 09, 10:37 PM posted to sci.physics,misc.fitness.misc,rec.martial-arts,alt.martial-arts.karate
Sam Wormley
external usenet poster
Posts: 1
Default the physics of situps

RichD wrote:
Long ago, in my wasted youth, I participated in
a weekend of sadomasochism, conducted
annually by my college karate club, called
'special training'. One part of this consisted
of a ton of situps.

We paired off, with locked legs, done by count.
It was impossible to do them all with good form,
so I came up with a trick: throw my arms forward
as hard as I could, on each one, to raise myself.

But Newton's physics tells us an isolated body
cannot generate net momentum; action = reaction.
But I swear I couldn't have completed that segment
without the arm swing. So the question is, did this
trick really work as a cheat, physically? Or was
it just an illusion?


Are you taking into account the differences in
static and kinetic friction?

Old May 10th 10, 07:53 AM
alfanzo alfanzo is offline
Junior Member
First recorded activity by FitnessBanter: May 2010
Posts: 2

The difference between a sit up and crunch is range of motion. With a sit up, you raise all the way up and will actually have no tension on your abs at the top. With a crunch, you don't raise up so far and constant tension is kept on the ab muscles.

As far as how you weight them, I don't think it matters. Move the weight around till you find what works for you. I set the plate on my chest for crunches. But I only use weighted crunches as my finisher. The two ab exercises I like to hit hardest are cable crunches and weighted knee raises.

I kneel and crunch to the floor on cable crunches. Sitting on a bench didn't seem to work as well for me. I go as heavy as I can go for 15 clean reps. I usually have to reduce weight as I go. I think those exercises focus on the abs much better with less stress to my back than crunches. But that's just me.

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
the physics of situps hal General 2 November 15th 09 03:00 AM
Problems with situps GlynneathJack General 2 April 19th 05 07:20 PM
Situps and pushups meirman Aerobic 8 December 9th 04 02:14 PM
Situps and pushups meirman General 8 December 9th 04 02:14 PM
How many situps? Roamer7 Weights 1 January 29th 04 06:23 AM

All times are GMT +1. The time now is 12:03 AM.

Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2004-2019 FitnessBanter.com.
The comments are property of their posters.