When BBC political reporter, Andrew Marr, suffered a major stroke in 2013, he believed one of the causes, aside from his heavy work schedule, was a HIT (High Intensity Training) session on his rowing machine. Here's what he said.
"I went onto a rowing machine and gave it everything I had, and had a strange feeling afterwards - a blinding headache, and flashes of light - served out the family meal, went to bed, woke up the next morning lying on the floor unable to move."
After intense therapy, he's returned to work with limited movement and has said he thinks he's luck to be alive. But should we be wary of training hard?
On one hand we're told to keep active and stay in shape, but on the other, can intense workouts pose a serious health risk? Obvious age is a factor, Marr is 54, but I believe it's not what you do - but how you do it.
I see many people in my practice that appear to use what I call 'the wrong kind of effort'. By this, I mean when they row, run or try harder, they stiffen their neck, shoulders and lower back - all of which make movement harder. It's like applying the brake on your car and then putting your foot hard on the pedal. Trying to accelerate with the brake on isn't good for your car, and the equivalent isn't good for your body either.
But somewhere along the way, many of us have learned some bad habits when exercising (or trying harder) and contract muscles when we should be releasing them.
I'll write more on my theory later, for now let's just look at rowing. When you're raising the stroke rate, or working against a higher resistance level, how do you do it. Do you lift your shoulders, tighten your lower back or pull back your head?
You may not notice if it's become a habit, so ask someone to watch, or video yourself and play it back in slow motion. You might be surprised to see what your doing with parts of your body and not have a clue you're doing it.
You may think you have to do this things when working harder, but it's not true. Try the following experiment during your next rowing workout.
As soon as you start to pull a face, or notice you've tightened your neck or shoulders, slow your rate and start back at step 1.
Why focus on the face? Your neck muscles play a vital role in coordinating your movement. If you clench your jaw, your neck muscles will also tighten - try it and see for yourself. Once your neck muscles contract your brake goes on and movement becomes harder.
Try the above for other activities such as running or walking hard. Keep it simple and just relax your face and see what effect that has on your movement. Top sprinters use this technique - watch their jaws move as they run up to 30mph. They know that relaxing the face makes it easier.
So it is possible to train for short periods of high intensity, but make sure you're not making it harder than it needs to be by stiffening your neck. Not only will this impact coordination, it can effect your circulation at a moment when your body needs it most.
See more on rowing technique here.
Roy Palmer is an athletics coach, teacher of The Alexander Technique and a rowing fanatic.