Hiking with Trekking Poles

What are the benefits of using poles?

The force that goes through your knees when descending is reduced. Many studies have looked to quantify this, and on average they have found that when descending the force going through your knees is 25% less when using two poles, compared to using none. When you consider that on descending a steep slope the joint reaction force between you patella (knee cap) and femur (thigh bone) is the equivalent of four times your body weight, you can see that anything that reduces the load can be a good thing.
Balance. Clearly having four points of contact with the ground rather than two improves your balance. This is especially useful on stream and river crossings and loose ground.
Going uphill poles give you more climbing power

Your hands are full, looking at the map/ GPS, having a snack or a drink is trickier
On some terrain poles are more of a hindrance than a help. Hands are more useful than poles when scrambling. On a narrow path with thick vegetation on either side poles will get in the way. Plas –y – Brenin the National Mountain Centre in Wales report an increase in accidents above the snow line where walkers have relied on poles when an ice axe should have been used, and consequently they have been unable to self arrest after a slip.

Generally two. Balance is better and load is more symmetrically distributed

You need the strap to be in a correct position over the wrist to allow the wrist to take some of the weight. If you do not hold the pole correctly you will end up having to grip the pole too tightly
Let the strap hang down. Put your hand through the strap from the underneath and take hold of the grip. This is the same way that you hold ski poles.

Start off with the poles adjusted so your shoulders are relaxed and elbows at 90 degrees
Shorten the poles when going uphill
Lengthen the poles when going downhill
On a long traverse make the uphill pole shorter and the downhill longer.

For normal walking and uphill put the opposite pole and leg forwards. i.e. place the left pole forwards with the right leg.
On steep descents you may feel better placing both poles downhill then stepping down.

Poles come with lots of features. You may want to consider the following:

Weight. The lighter the better, but they still need to be sturdy and durable.
Telescopic poles. Two or three section poles allow the pole to be collapsed and carried on the rucksack during sections of the walk when they are not needed. Three section poles collapse down smaller than two section.
Adjustment system. This can be external (eg Black Diamond Poles) or internal (eg lekki poles) External tend to be easier to adjust with cold hands on or gloves, but get clogged with dirt and grime and look slightly less neat.
Grips- try them out and find one that is comfortable for your hand size
Tips- Choose a tip depending on the surface you intend to be doing most of your walking on. Some poles have changeable tips and baskets.
Shock absorbers- make the pole less rigid and therefore decrease the efficiency of the energy transfer. Probably only worth considering if you have painful wrists or shoulders.
Added accessories – it’s possible to get various fittings eg ice axe, camera tripod. Consider how much you will need these.