Just a branch will do if you believe that just a board will do for a pair of skis.
There is a physiology involved in trekking poles; a stave is just a balancing device that uses one arm to drag it along. Many pilgrims don't use them, but do not think that grabbing a branch will give you the same benefits as trekking poles. It won't happen. Pacer Poles may be an improvement on the established trekking pole physiology. Anniesantiago will let us know in a few weeks.
From a pole-hater:
II. The "Pro" Side: Advantages of Trekking Poles
Most obviously, poles reduce the impact of hiking on knee joints and leg muscles. Arm and shoulder muscles support and relieve the leg muscles. With the basic "hands above the heart" position necessitated by the poles, circulation is improved and heart rate is reduced. The "rhythm" created by walking with poles leads to relaxed, more regular breathing and increased stamina.
A landmark study published by Dr. G. Neureuther in 1981 proved that use of "ski poles" while walking reduces the pressure strain on the opposite leg by approximately 20%. Furthermore, while walking on level ground, poles reduce the body weight carried by the legs by approximately 5 kg every step. Move to an incline, and that reduction increases to 8 kg. This translates into tons of weight -- yes, tons -- for even a two hour hike.
Jacquie Hunt, editor of a popular hiking newsletter, weighs in with additional health benefits: "An advantage that I found once I started using poles is that my hands no longer swell up when it is hot. Keeping your arms moving so the blood doesn't pool in the hands is a lot safer than keeping hands high on pack straps and risking a smashed face if you trip."
Finally, poles help many people with balance issues. We all have different comfort levels when balancing along puncheons, crossing streams, etc.; for some hikers, trekking poles are worth their weight in gold. They can certainly aid when crossing soft ground, and can be indispensible [sic] for tasks like river crossings, and scree running.
III. The "Con" Side: Problems with Trekking Poles
There are two categories of drawbacks to hiking poles -- those legitimate, and those perceived. One of the main problems with my comments in the LA Times article is that my "over the top" approach precluded me from stating the legitimate drawbacks to using poles. So here goes...
First, using poles increases your total energy expenditure. Your arms were not designed to prop up your body, nor to distribute weight. Even Peter Clinch, whose "Pete's Pole Page" is long recognized as an on-line authority, says, "...if you have tired legs and knees then poles can be a win, but if you have a tired body, with your cardiovascular system at its limits, then poles may be more of a hindrance than a help." Those "tons of weight" that poles save the knees aren't carried up the hill by themselves. Many hikers with good legs are unaware that they actually may run out of gas more quickly by using poles.
Not only do poles make hands and arms do what they aren't designed to do, they prevent your hands from being hands! Open the map, eat a snack, wipe your brow, grab a rock, snap a photo, read a compass...all of these become clumsy and time consuming with poles in hand.
The final "legitimate" con is that many people simply do not use poles correctly. Clinch says, "judging from the people I see in the UK using poles, the majority of folk get little or no benefit from them." Without proper technique, poles are simply in the way. And that brings us to the "perceived" drawbacks.