Expert: Alan Kahn - 2/20/2007

Question
Your answer to Tony was of great value; thank you.  My situation: the bag I bought is an Everlast 4214.  The instructions say to fill to 4 pounds; since I don't have any way to measure the air pressure, I filled it until it was firm, but not hard (less than a basketball).  Over time the pressure drops, the action slows, and I reinflate it.

My question ... how important is the air pressure?

Second item: my bag does not look like the ones I see in movies and advertisements.  My bag is not as long, and is more round.  Is it just the design of my bag?  What advantage or disadvantage is there to an elongated bag?  Or to the rounder bag that I have?

I also noticed that there are 3 sizes of bags: is there a functional difference in the size of the bag?  Which size is best?

Answer
Hi Elmer,

I think Air Pressure is very important. It provides the internal resistance for the bounce in the rebound. It Sounds like your bag has a slow leak. This can be either a small pinhole leak in the bladder or a bad air valve. Outside air temperature can influence your bags pressure also, and cold air makes if a little flatter. Eventually you will probably notice your bag goes flat (loses air) faster and faster over time. A slow leak usually gets worse.

On your second point concerning speed bag shape, that is variable and it does change occassionally. Historically, sizes and shapes have varied with materials and manufacturers. Bags in the "old days" (1900 - 1940's) were Big and Large balloon looking behemouths. Here's a few pictures below:

http://www.kshs.org/cool2/graphics/cooljess.gif

http://www.pugilistica.com/BoxingArchive2/EddieSimmsC1936WorkingSpeedbagInGym.JP...

http://www.pugilistica.com/BoxingArchive1/JackDempsey1927trainingwithpulleysbefo...

http://www.antekprizering.com/braddocktraining003.jpeg

http://www.sports.nd.edu/exhibits/winkexhibit/Canzoneri.710-5-50.jpg


Now they seem to be smaller, and range in pretty standard sizes, but the shapes vary.  Some makers prefer the longer, leaner looking speed bag shapes, such as this:

Ringside boxing brand bags (2006 shape)
http://www.ringside.com/DETAIL.ASPX?ID=25256

or the more teardrop "rounder" bags
http://store.titleboxing.com/title-pro-mex-professional-speed-bags.html

Titleboxing brand bags.
http://store.titleboxing.com/titlespeedbags1.html

The one you like is personal preference. Personally, I like the shorter, more round shaped bags. I like them because I think they are slightly faster (fatter belly hits the board quicker) and there is less bag area under the "belly" (fastest part of the bag) making it easier to "pass the hands through the bag" to the other side. Remember, though, I hit from all sides of the bag, so it is important to be able to get my hand past the body of the bag.

Here are some videoclips of me punching to demonstate that:

speed bag punching
http://www.youtube.com/watch?v=2E9bmT4_twU

speed bag "Danger Zone"
http://www.youtube.com/watch?v=55DcX1TfCOc

speed bag beat
http://www.youtube.com/watch?v=qhk6DgY6lYY

Shorter, fatter bags just seem to make punching like this easier, so I stay away from the long, lean "bananna" bags.
++++++++++++++++++++++++++++++++++++++++++++++++++

As for bag SIZE, there are really more than three sizes, unless you want to say there is "small" 6x4, 7x5, 8x5
"medium" 9x6, 10x7, and "large" 11x8, 12x9 or larger.

The bag size is important for a few reasons. Large and medium size bags are usually easier for a beginner to control, and more forgiving of a miss placed punch. They are also great for power and strength workouts. Smaller bags are more difficult to control, so take more ability to keep them going, and are great for working real hand speed, faster rhythm and timing, and faster eye-hand coordination. Punching larger or small bags at near full power is also very cardiovascular. (I add in cycles to increase cardiovascular and coordination components)

Here is a unique comparison of speed bag size vs weight on speedbagforums.com (with smaller bags, but still interesting)
http://www.speedbagforum.com/forums/showthread.php?t=201

so it is hard to say which is BEST, for it depends on your punching ability and the focus of your workouts. check out some specialized workouts with different bag sizes here on Speedbagcentral.com

Focused speed bag workouts.
http://www.speedbagcentral.com/ssp/focused_workouts

unique speed bag workouts
http://www.speedbagcentral.com/ssp/unique_workouts

and for our friends needing some rehabiliation
http://www.speedbagcentral.com/ssp/rehab_training

I hope this answers your questions, Elmer. Good luck in your training.

sincerely

Alan Kahn
author, The Speed Bag Bible