This is a debate that has been heard by all of us one time or another, I believe: Should strength training be incorporated into HEMA, and how much of it should there be? The extreme usually goes towards having a minimum of strength training, focusing on form and technique instead. Well, I believe it's time we take a bit more theoretical approach to the issue. Thus, I've conducted a short research, and here are the results:
Learning strikes, techniques, footwork and the like is achieved through the phenomenon of motor muscle memory, the basic premise of which is this: the more you repeat a certain action, the better you get at it. A premise accepted widely enough. However, even this seems to have two stages: one happening mainly in the brain, called memory encoding; this term is also generally used for non-physical encoding.
This means the brain is actively connecting the actions needed to make the strike or technique, it is effectively re-mapping our neural pathways so that we are able to perform the action we wish to most effectively. Of course, this is also strengthening over time, as our understanding of strikes and techniques grows better through repetition. This part can be done rather slowly, and should be done so with beginners, so that they do not encode any big mistakes. Once the basic movement has been mastered, however, there is nothing wrong with adding speed to it.
Consolidation means that the strike has moved to the longterm memory, and thus can be performed much more quickly. What is also of note is that in both stages, synaptogenesis happens: We get new synapses, enabling our nerves to communicate better. Nerve excitability in general is improved, allowing us to make our movements faster. Not only that, through repetition it would seem as if our spine takes over most of the work, shortening the distance and allowing for even better, faster strikes (it is theorized that the brain needs less error correction and so makes it possible for the spine to take over).
So this can be achieved with skill training. For the first part, solo drills with long and short edge are great tools for advancing, as well as drills with a partner. For the second (which should come after the basic movement is good enough, so after the encoding has been sufficiently completed), an exercise which focuses on as many repetitions of a single strike as quickly as possible in a short time interval is most appropriate. So why would we even need strength training? Surely you can build up enough strength through skill drills.
As far as strength training goes, there seems to be a fair number of people claiming it really isn't all that important in swordfighting. Seeing the information above, it isn't too difficult to see why. However, reality is not quite so simple.
To quote the font of all knowledge, which in turn quotes an academic research in this instance: ''strength training enhances motor neuron excitability and induces synaptogenesis, both of which would help in enhancing communication between the nervous system and the muscles themselves.'' Simply put, strength training makes your neural connections even stronger. Not only that, ''neurotropic factors within the motor cortex are upregulated in response to endurance training to promote neural survival,'' meaning that retention of what you learn in HEMA training is higher when coupled with endurance training (not quite strength training, but not skill training either).
What is important is that both things are done regularly; it won't help much if you have skill drills one week and strength training another, but it will be greatly benefitial if you train HEMA one day, and strength the next. Of course, there can be a day's break in between, and it is in fact recommended for regeneration.
In the end, it isn't about strength vs. skill training, as many seem to believe. The fact is, they are interconnected. This is why we see so much strength training in all sports and competative martial arts: it helps you learn faster. It isn't just about being stronger, or having a quicker strike. It's about having the optimum condition for learning the Art. And strength training, which seems underrepresented in HEMA today, is a big part of it.
Sources and further reading:
Adkins, DeAnna L., Boychuck, Jeffery. 2006. Motor training induces experience specific patterns of plasticity across motor cortex and spinal cord. Journal of Applied Physiology. 101: 1776-1782; also available through: http://jap.physiology.org/content/101/6/1776.long
Figure 1: http://psychclasses.wikispaces.com/Group+-+Chapter+07+-+Memory – taken on 2nd December 2012
Figure 2: http://scienceblogs.com/purepedantry/2007/03/06/neuron-to-glia-synapse-on-axon/ - taken on 2nd December 2012
Figure 3: http://www.vision-academy.co.uk/kettlebells - taken on 2nd December 2012