Archive for May, 2019

Interpreting messages from the body to the brain

May 27, 2019

My hopes of blogging more frequently in 2019 have so far been frustrated by a heavy schedule at work.   But even more frustrating has been the fact that during the past few months various things have made it difficult to find time even to run. These things have included preparing our house for sale and attending academic conferences.  Potentially more promising with regard to opportunities for running was the task of bringing our newly purchased canal boat from the south of England to the Midlands. Canal boats travel slowly and the journey took more than two weeks.  During journeys in our previous boat, I usually made the most of opportunities to run along the canal tow path, circling back as required to assist with the task of opening lock gates. However our new boat is much longer and has a deeper draught than our previous boat. Our route to the Midlands included the River Thames from London to Oxford and thence northwards on the Oxford canal. The wide river offers relatively few opportunities to disembark to run along  the riverside path. The Oxford canal meanders through delightful countryside but is notoriously shallow. With the deeper draught of the new boat we faced the risk of running aground. It was best for me to remain on board, prepared to use a pole to lift the bow slightly and nudge the boat towards deeper water, while at the stern my wife put the engine into reverse at appropriate moments to enable the propeller to force water beneath the flat bottom of the boat.  It was a journey with delightful memories, but sadly I did not run along the canal tow path at any point.  As a result, I am now at a lower ebb of fitness than at any time in the past 15 years.

 

Three days ago I set off for a run across the Lakeland Fells. I had no intention of running at even a moderate pace.  My intention was to begin to rebuild some fitness while enjoying the spectacular mountain scenery.  On the steep ascents I clambered upwards maintaining at least three points of contact with the rock over craggy outcrops; on the descents my main goal was to remain upright.   However, on the grassy level ridge-top, I was dismayed by how uncomfortable I felt.  Although my pace was slow, the depth and rate of my breathing told me I was near the upper limit of the aerobic zone. To my dismay, I felt a strong urge to stop and walk.  It is very rare that I ever feel the urge to stop when running. When pushing hard I often need to dig into my reserves of determination to sustain the pace, but I am rarely tempted to slow to a walk.  At first I was inclined to acquiesce to my body’s clamour for respite and simply enjoy the scenery. But before acquiescing I wondered about the nature of the signals my body was sending to my brain.

I was definitely short of breath. No doubt the accumulation of carbon dioxide and acidity in my blood was triggering a barrage of moderately insistent messages from the chemoreceptors in the large blood vessels to my brain. But I usually interpret this level of breathlessness as exhilaration rather than distress.  In addition, my leg muscles felt a little sluggish.   However, there was none of the sharp pain that arises from the transient accumulation of lactic acid when running at speed, nor the dull ache that arises from microscopic damage to muscles after an hour or more of running.  In reality, none of the signals to my brain could be interpreted as pain; they were merely markers of effort.

Possibly on account of the need to avoid wasting precious energy reserves faced by our distant forebears living on the African savannah 2 million years ago, our brains are predisposed to minimise unnecessary effort.  However, in a world where we are no longer prey nor predators in everyday life, this natural predisposition to minimise effort tends to be far too over-protective.   While it is necessary to be a little cautious when returning from a lay-off from running, at this stage of my run, with only a few miles behind me, there was little need for caution.

It was time to reinterpret these signals from body to brain.  The sensation of effort was cause for satisfaction rather a signal of need for rest. However, my legs felt unpleasantly clunky.  At this point I shifted my focus from the clunkiness of my legs and engaged a few of the tricks than promote fluent form.  In particular I focussed on the rhythmic swing of my arms, allowing the down-swing of each arm to pace the lift-off of the opposite foot from stance.   The sensation of clunkiness disappeared.  Despite my slow pace I began to feel like a runner once again, running freely along a mountain ridge with the central Cumbrian Fells defining the skyline ahead of me and the intricate facade of the distant Howgill Fells away to my left, across the valley of the river Lune that marks the natural border between Cumbria and Yorkshire.    I am still far from fit, but it is good to once again feel that I am a runner.

Advertisements