A question for the physiologists and training experts here, would really appreciate your expertise and thoughts on this, as it’s not actually something I have ever seen discussed.

There is a type of exercise where you take muscle groups to exhaustion by pushing them to their limit, but over a medium period of time rather than the very short period of a weight training set. Paddling (lying down) on a surfboard, where you go at it as hard as you can, after a while you can barely lift your arms above your head any more is probably the one I have most in mind here. But we are finding it in stand-up paddleboarding and outrigger paddling (etc) as well, where you are pushing down on the top of the paddle as hard as you possibly can. And eventually you just run out of power, but, as you get fitter, you can go for longer. And as anyone who surfs occasionally knows, what normally finishes your session is when you just don’t have any power left in your arms and shoulders to paddle back out there. But if you do it regularly, your endurance grow. And you can paddle harder, too. But it’s not at all about aerobic capacity or fitness, it really is specifically about those muscles. Climbing is another example where eventually you just have no strength left in your arms.

So what is actually going on here, from a physiological point of view? Are the muscles being built up? If you keep doing it will you actually generate more muscle mass in those body parts, or is it just a case that the muscles in question getting better conditioned? Can your muscles get stronger while not actually getting bigger? Because you don’t tend to see pro climbers looking bulked up, but these guys can do one-armed pull-ups till the cows come home. And likewise pro surfers are generally really well conditioned and ripped but not carrying massive amounts of muscle.

And if you are doing lots of training of this sort (or even just from a recreational point of view, going off on a surfing trip where you want to be out there as much as possible), what would be the best advice to look after your muscles with regard to however they’re developing. Obviously higher carbs because of the calories burned, but would it be beneficial to significantly increase the protein intake too?

Would really appreciate some expert explanations on this – many thanks in advance!