Posts Tagged ‘biomechanics’

Kayaking Back Pain and Leg Numbness (Part 1)

Sunday, February 10th, 2008

First, some basic mechanics:
According to Isaac Newton’s Third Law of Action and Reaction, whenever a body exerts a force on another body, the latter exerts a force of equal magnitude and opposite direction on the former.

In other words, when your legs push your feet against your kayak’s foot braces (or footrests) they also push your lower back against your seat - and as a result the seat pushes back against your lower back with an equal force.
Your legs have the most powerful muscles in your body, and they constantly generate this force from the moment you sit in your kayak until you get out of it.
The L kayaking position deprives your legs from their natural role, and together with the seat and footrests turn them into a source of ergonomic problems for your back.
All that unnatural pressure is bad for your legs as well, and this is why you suffer from leg numbness, poor circulation and sometime pain and even chronic injuries.

The traditional kayaking position


The Evolution of the Kayak (6)

Monday, February 4th, 2008

Raising the Bar in Kayak Design and Performance:
New Standards For The Third Millennium

 

This article discusses the changes in kayak design, usage and performance over the past century and in recent years.

Part 3
Ergonomics: From a single, uncomfortable position to the freedom to choose from a variety of ergonomic positions

 

4. VARIATIONS ON THE L POSITION - TRYING TO DEAL WITH A PROBLEM BY CREATING DIFFERENT ONES

Manufactures of monohull kayaks who tried to depart from the L position by offering higher seats found that they needed to increase their kayaks’ width considerably in order to compensate for raising the paddlers’ center of gravity (CG). This was done only to rediscover the fact that excessively wide kayaks track very poorly and are harder to paddle.

5. THE NATURAL SOLUTION: THE W KAYAK POSITIONS

The W departed completely from both the monohull design and the L kayaking position.
By offering much better lateral stability and a high saddle the W Kayak has enabled a new set of comfortable positions and a wide range of intermediary positions, as well as the possibility to alter your posture anytime you feel like it.
This is achieved without widening the kayak - In fact, the current W Kayak models are only 25″ wide, which is as wide as some sea kayaks are.
The key to improving comfort and performance in paddling and fishing is the new, full role played by your legs: Instead of pushing horizontally against your lower back as they do in the L kayaking position, your legs support your torso vertically - from below, in the W Kayak riding (mounted) position. This is our legs’ natural position for locomotion and other major physical efforts. For this reason the W Riding (mounted) position is not only ergonomically better (I.E. more comfortable) but it’s also better biomechanically, that is more efficient in effort terms and more effective in performance terms of power output and control level.

The four basic W positions are: Standing, Riding (Mounted) with your legs on both sides of your body, Sitting with your legs forward (similar to sitting in a canoe), and Kneeling - a position preferred by some canoeists.

For more information visit Wavewalk’s website Ergonomics section.


The Evolution of the Kayak (5)

Monday, February 4th, 2008

Raising the Bar in Kayak Design and Performance:
New Standards For The Third Millennium

This article discusses the changes in kayak design, usage and performance over the past century and in recent years.

Part 3
Ergonomics: From a single, uncomfortable position to the freedom to choose from a variety of ergonomic positions

1. HOW THE TRADITIONAL, L KAYAKING POSITION CAME TO BE

The native kayak was a ‘man’s boat’ - that is a hunters’ boat. What it practically meant was that the native hunter in his kayak had to approach prey such as swimming caribou, beached seals or certain bird species from the shortest possible range in order to effectively shoot a harpoon or an arrow at them. To remain unnoticed from the shortest range the Inuit kayaker needed to stay low above water. In fact, for whaling and long sea trips the Inuit preferred to use their bigger and stabler canoe-like Umiaks.
Since stealth was important for native kayak hunters they paddled in the low, traditional L kayaking position with their legs stretched forward. People around the world used to sit on the floor in similar postures before nearly everybody adopted special sitting furniture such as stools, benches, chairs, sofas, armchairs and other seats.

The kayak is rather unique boat in this sense since native canoes around the world usually offered additional, more comfortable and powerful positions such as sitting higher, kneeling and standing.
Interestingly, the L is not the only position that monohull kayaks offer: Some whitewater canoeists take kayaks and ‘convert’ them into ‘canoes’ just by adding a very low saddle inside their cockpit. This arrangement enables them to kneel inside on both knees in one of the traditional canoe kneeling positions, and paddle with a single-blade paddle (I.E. canoe paddle). The reason why only few paddlers ‘convert’ kayaks into ‘canoes’ is because that particular kneeling position is even less comfortable than the traditional L kayaking position, and this may be the reason why some of these canoeists call themselves ‘pain boaters’…
This leaves modern monohull kayakers with just one position to choose from, and it’s not an ergonomic one. That’s not much in terms of freedom of choice, especially when one considers the fact that in their everyday life modern kayakers are used to a variety of seats and sitting positions that do not include the L position.

2. THE MODERN L KAYAKING POSITION - TRYING TO SOLVE A PROBLEM BY CREATING ANOTHER

Seats and foot rests (a.k.a. ‘foot braces’) have altered the L position without improving much: The backrest prevents the kayaker’s torso from ‘falling’ backwards but it makes it slide down and forward. In order to counter affect this problem modern kayaks offer support for the kayaker’s feet: By anchoring their feet in those small depressions or ‘braces’ kayakers can stop their bodies from sliding down and forward.
However, the combined backrest and footrest system created a new problem, which is constant pressure on the kayaker’s lower back. This pressure is generated by the kayaker’s own legs pushing against both footrests and backrest like a powerful spring. The negative physiological impact of this pressure is felt as fatigue, discomfort in the legs and back pain. The problem is amplified by the kayaker’s inability to switch to other positions. Some kayak seats offer a rigid support for the kayaker’s back and other kayak seats offer heavily cushioned support, but four decades of experimentation proved the L position to be an ergonomic dead end.

3. BIOMECHANICAL ISSUES WITH THE L POSITION

Our legs have the most powerful muscles in our body and they are naturally best fit to do the hard work involved in locomotion and balance. The L kayaking position prevents paddlers from using their legs effectively for balancing, controlling and propelling their kayaks. Therefore, the kayaker’s back, abdomen, shoulders and arms must do considerable extra work. This effort distribution is insensible from a biomechanical standpoint, which means you’re spending energy for nothing and get tired more quickly while your kayak delivers less performance than you need.

Kayak Fishing From the Mounted (Riding) Position

Thursday, January 31st, 2008

While the advantages of fishing standing are pretty obvious to most fishermen many who haven’t tried the W Riding (mounted) position may wonder what’s so special about it, and why it is considered so advantageous when compared to the traditional L kayaking position or to fishing seated in a canoe.

The answer is that it has to do with how much support you have for your casting and reeling-in efforts, as well as when you’re fighting a strong fish:
The result of every physical effort you make, whether it’s jumping, running, pulling or throwing something depends on the kind of support your body gets from the ground you stand on. Soft, slippery or shaky ground doesn’t offer you good enough resistance.
Similarly, fishing from a big boat enables better physical performance than fishing from a small, unstable one: You can cast to longer distances and fight bigger fish more easily.
Riding the saddle of a W kayak doesn’t offer you as much stability, support and confidence as the deck of a big bass boat, but it certainly gives your legs more support than a sit-in or SOT kayak does, and through your legs you get more support and power for your arms and upper body.
Imagine riding a pony, which is similar to riding a W kayak saddle: The horse rider can gallop and jump hurdles, throw a spear or shoot arrows like ancient warriors used to do, or a lasso like modern days cowboys still do, and so on. -Now try to imagine all this being done when the rider sits on the horse’s saddle in the traditional L kayaking position… It’s practically impossible because the rider lacks stability and sufficient support from his legs.
Like any analogy this one is not perfect but it’s close to the truth: The combination of having two hulls on the W kayak’s sides and riding the saddle that you mount in a posture that’s advantageous from a biomechanical standpoint changes everything when you fish.

As Jeff McGovern puts it: -”I would venture to say the W offers improved casting with any gear. From the riding position, I get more power with my casting and spinning because I can put my whole body into the cast and use my legs. The solid feel of the boat gives you a great sense of security. ” (Read More)

Riding (Mounted) position: Best for kayak fishing Riding (Mounted) position: Best for kayak fishing (2)