So you want to PB? Have you taken a look at your strength program recently?
Thought not. And fear not, I get it, you're in a safe space here. The weight room is not the standard habitat for the fleet footed, pigeon chested, shaven legged Endurance Athlete. Even the words "strength program" can strike fear into otherwise steely-eyed, determined individuals.
It is however, a necessary evil. And it can be your secret weapon too. I've lost count of the number of athletes I've seen smash through plateaus just through changing (or starting!) their strength work. I've also witnessed far too many individuals do entirely the wrong thing, resulting in no improvement, frustration and injuries. The key is correct exercise selection, and adherence to a program. To get to what is right however, we must first consider the task at hand.
Any long-distance endurance activity is essentially thousands of repetitions of one movement. Whether via bike, in the water or on your feet, these cyclical, repetitive movements are the hallmark of endurance sport. It is their repetitive nature that stands out, and thousands of reps of one movement in one direction is a recipe for one thing: Joint imbalances. So how do we correct this and why will it help my running/cycling/swimming so much.
Balance around Joints
The body is a stack of joints. Muscles act on joints in agonist/antagonist pairs to create movement (e.g at the knee, the quads and hamstrings act as a pair). From ankle to neck we are designed to move, twist and leap. All joint have a balance of strength and mobility around them, some joints require more range (shoulder) and others more stiffness (knee). Constant swimming/running/cycling leads to an over-development of certain muscles and an under-development of their antagonistic counterpart. Cyclist often have superb quadricep bulk and strength, but are incredibly weak in the hamstrings. This balance affects the position of the joint, as one side is exerting much greater force than the other. Simultaneously, weak muscles (hamstrings) begin to feel tight because the over-dominance of one muscle (quads) changes the position of the joint(s), resulting in feeling of tightness that are actually rooted in weakness.
What to do?
The simple answer here is: do what you suck at. Nearly everyone is over dominant in the quads and chest, so in your next gym session, leave the squat rack and bench press alone. Focus instead on single sided stability work around the muscles you don't use as much during your chosen sport. Runner? Hammer your single leg hamstring bridge and tibialis anterior raises. Cyclist? You likely need the same hamstring work and a lot of core. Swimmer? horizontal rows and rotator cuff for you.
Why will this help?
Simply put, economy. A body that is better balanced is a body than can more efficiently transfer force. So much energy is wasted due to poor technique, but this usually stems from an inherent weakness/inactivity of whichever supporting muscle it may be. Strengthening supporting muscles is one of the easiest ways to reinvent yourself as an athlete, you just need to identify precisely what you suck at....