The adductor complex is undoubtedly one of the most integral muscle groups in the human body...
But it's also a viable candidate for the most overlooked.
So how and why has such an important complex been nearly forgotten about when it comes to direct training?
The short answer: it is just pretty damn hard to find effective ways of isolating the adductors.
Unlike muscles like the quads or the delts or the glutes that can be easily programmed for with a medley of specific variations and techniques, the adductors find the majority of their utility through secondary functions: namely, in stabilizing the pelvis and femur during movements like squats, deadlifts and lunges.
Whereas our quads and glutes and even hamstrings will get a massive degree of stimulation from direct lengthening-shortening cycles, we rarely perform purposeful hip adduction.
In fact, I can almost guarantee that if you were to google search for "Leg Day" that an adductor-specific variation wouldn't show up in the top 10 results, and in my opinion, this needs to change...
Strong and healthy adductors have MANY positive effects:
1) The muscles of the thigh are typically thought of as just the quads and hamstrings so most trainees focus the bulk of their hypertrophic efforts on these groups. But well-developed adductors can contribute just as much, if not more, to the circumference of the upper thighs. Training them directly will grow your legs!
2) One of the more common and frustrating injuries is the groin strain. These seemingly mild ailments tend to persist for weeks and months, turning what should have been a minor setback into a program-halting issue. Direct training of the adductors will strengthen and bulletproof this region (adductors and "groin" are typically used interchangeably) so that strains will become much less common and those that do occur will be rehabbed in much less time.
3) Note how I keep referring the the adductors as a complex rather than an individual muscle. That's because there are multiple contributors that assist in the function of hip adduction, and they collectively make up the larger complex. The biggest and most powerful of these is the Adductor Magnus, but we also have the Add. Longus, Add. Brevis, Add. Minimus, the Pectineus, Gracilis and Obturator Externus. Memorizing each of these muscles isn't important but what is relevant is their specific actions—yes, they're all mainly responsible for hip adduction, but they also assist with hip flexion, extension and internal rotation. Having a strong adductor complex doesn't just stabilize during heavy squats and deadlifts; it actively assists through those movement patterns.
4) In addition to all of the above, directly training the adductors (through multi-planar hip adduction) actually creates more degrees of hip mobility. That mobility allows for more ROM in things like squats, sumo deadlifts and leg presses which leads to a greater growth potential for the quads, glutes and hamstrings. And because the adductors have been strengthened in those ROMs, the risk of injury is lower as well.
So now that we understand how important is is to have well-functioning adductors, how exactly do we achieve this?
We're back to our original problem...there just aren't many ways to easily and effectively train hip adduction.
There is the Seated Machine Adduction that can be found at some commercial gyms, but other than that, there is ????
Finding ways around this problem requires some creativity and ingenuity—I can think of more than a few ways to build, strengthen and solidify the adductors, but nothing comes close to the Copenhagen Plank in practice.
Before rushing to throw it in your next leg day, here are some things to know about Copenhagens:
1) They can be static or dynamic. Start with the static "plank" to build tolerance to the movement and then slowly progress towards dynamism as your adductors get used to the novelty.
2) While there isn't the convenience of a pin and weight stack to change resistance, you can easily titrate how much load your adductors handle by adjusting the fulcrum (placing of the bench/pad). The higher up your leg, the less tension that will be placed on your adductors. And vice versa. I recommend everyone start with the fulcrum on their lower thigh and above the knee.
3) It is important that the tension is eased into at the beginning of every set. Even though your adductors may be strong and adapted, this is still a 0-100 scenario with no real way of performing warmup or feeder sets. So it's good practice to use your bottom (downed) leg to act almost as a spotter and slowly "hand off" the full tension of your bodyweight to the working leg.
4) Intensity progressions won't be coming from adding load as they might with a machine. With Copenhagens, slowed tempo, ROM alterations, and static holds at varying degrees of hip abduction are going to be the main ways to ramp things up beyond the normal eccentric/concentric paradigm.
5) Not everyone will be able to comfortably perform even the static holds. This is a relatively advanced "plank" variation that happens to require a solid amount of prerequisite strength. There are ways of regressing the Copenhagen further depending on the weak link, but it should be clearly understood that this is NOT the movement to throw caution to the wind with. Scale down if you need to scale down.
Now that you're ready to introduce Copenhagens into your programming, use this structure to get the most out of them:
1) Start with the static variation with the fulcrum on the lower thigh for 2-3 sets of 20-30 sec holds as a prehab movement before your actual working volume
2) Once you can comfortable hold for 30 sec on each side with this positioning, move to dynamic reps with a 3001 tempo.
3) When you can achieve 15 reps on each side like this, move the fulcrum to your ankle and revert back to the static plank.
4) Go through the same process until you can get 15 dynamic reps at the ankle.
5) Once you can do this, you can utilize the movement as real adductor training rather than just preventative work.
Clearly there is a lot more than meets the eye with the adductors and the proper ways to train them. And while Copenhagens are by no means the only way (I would recommend using that seated machine if you have it!), they are going to have a massive positive effect for growing, strengthening and stabilizing your adductor complex.