It is a question of resolve, of will. I am going to row directly into the pain. I will row faster and faster. Blood will pool in my head and turn my vision red. My whole body will ache, and there will be a rictus of agony on my face. I will row until the pain is blinding, until it shuts out everything, until I can’t think of anything but my stroke rate and the water on either side of the sculls. And then if I’m still awake, I’ll row on.
In a rowing machine the law of the lever is no longer that which determines the speed of the boat—it is the human body, inverted at a 90-degree angle, pulling on pair of lever arms. This means that a trainer on a rowing machine can measure how hard you’re working on a scale of 1 to 5, with 1 being an “active recovery” pace (https://www.medicalnewstoday.com/articles/active-recovery) and 5 being flat out. The goal is to stay at 4, because 5 is unsustainable for any length of time. At 4, the heart rate stays in the training zone, the lactic acid builds up just enough to provide an edge without inducing exhaustion, and the calorie count soars.
When you use the machine in the way it is intended—as a tool for structured interval training—it can be one of the best strength-building machines in the gym. At moderate weights it is the closest thing there is to real rowing, because it forces you to use all the muscle groups that you use in real rowing. There are, however, certain machine-training protocols that are better than others, and if you employ them you will wind up with much better preparation for an actual workout, or for competition. The main hazard in using the machine is the tendency to overtrain; when you work out on a rowing machine you use your muscles in an explosive manner, and you therefore exacerbate muscle-lengthening contractions in the muscle cells. The result is that after each workout your muscles will be in need of considerably more recovery time than they got in the previous week.