The Great Debate - 4x4's vs Intervals

Not that long ago I had an athlete who experienced a huge leap their performance, after just over two months of training they went from occasionally redpointing .12a to onsighting two .12b’s in a single session. Success! It’s one of the things that makes coaching worthwhile, guiding an athlete and seeing them achieve their goals and realize their potential. “I know it’s because of the 4x4s, that’s definitely what did it” they told me. Um, was it? Are you sure it wasn’t one of the many other training facets we’ve been working on? “What about the interval boulders, those seemed to really suit you well?” I asked. “No, it was the 4x4’s for sure”… Let’s try and unpack the “why” behind that statement.

For anyone who’s unfamiliar with the terms 4x4s and Intervals, let’s start by taking a step back and look at the meat and potatoes behind these two Endurance/Power Endurance training methods.

The 4x4 or Four by Four is the combination of four climbs, typically boulder problems, climbed back to back with no rest between each. After those four are completed, a specific rest period is taken (usually about four minutes) and then the group of four climbs is repeated again, and again twice more with the same rest periods. Essentially it’s 16 climbs done with very specific resting parameters, the emphasis of the drill being placed on longer work periods and limited rest. The traditional 4x4 has been around for a very long time in training circles. I remember dabbling with these in the late 90’s as a teen after hearing that “all the strong climbers down in Lander” were doing these and sending routes of unimaginable difficulty.

Interval training is also a combination of four (or more) boulder problems but without the specific volume of 16 total climbs and more attention paid to the rest portion of the workout. Interval boulders can look very different from coach to coach but perhaps the biggest common theme is the rest period, it’s equal to or greater than the TUT or time under tension (time spent climbing). Again the idea of interval training is not new. In 2003 I was introduced to the idea of interval training after reading a short article detailing Josune Bereziartu’s recent ascent of E la Nave Va in Switzerland - side note - This is still in my mind one of the most underrated achievements in the history of our sport. The font traverse scale 8c (V13/14 - 5.14d) climb is over 100’ of sustained micro crimping with almost no rest. Her training consisted of gradually increasing the duration of hard climbing coupled with equal amounts of rest (1:1 work to rest ratio). Modern interval designs tend to stay in this 1:1 - 1:2 work to rest ratio terms.

Josune Bereziartu on E la Nave Va (V14-5.14d) - photo by Rikar Otegui

These are two variations on climbing circuits that have long histories in our sport and both seem quite effective, so is one better than the other? Firm answer - No, they’re just very different and need to be used appropriately.

Let’s break down the 4x4 first. I personally believe it’s as popular as it is due to its simplicity. There’s not really that much to juggle, 4 problems and a stopwatch, pretty simple. Metabolically the 4x4 is very different from interval variations though due to that resting component. 4x4’s largely exploit the lactic energy system which is good for up to about 90 seconds. They feel so hard because they more or less deplete that energy reserve each time despite what seems like ample rest afterwards. 4x4 problems should be done at a grade range that’s “doable” call it 40-60% effort or around flash/onsight grades. The goal of this exercise is to stay on the wall and given the volume of climbing you wouldn’t stand a chance doing these with redpoint or project grades. Rounds 1 and 2 usually feel pretty good (ah hubris), rounds 3 and 4 however tend to feel like total redline and often result in failure - particularly round 4. This is usually a good indicator that you’ve dialed in an appropriate level of intensity.

By pushing the Lactic energy system to failure again and again, growing increasingly tired is inevitable. 4x4’s are training to reach near max fatigue. Now you might be thinking “Why, what the hell is the point of that”? I love using 4x4’s for conditioning early in training. I like to dial down the intensity of the climbing and use them to push an athletes energy system just enough to force it to adapt to more work. Next I like to use them as a “topper”, a finisher or polishing exercise for athletes looking to enter into a redpoint or performance phase. The common denominator there is that athletes work with these regularly, 1-2x per week in a training block. That consistency is what makes them effective. Without that consistency the just feel crippling and won’t help you adapt, they’ll just put you into a hole.

Interval training regardless of its structure is based around one guiding principle - staying at or above a 1:1 work to rest ratio. The only other guideline I like to follow is that the climbing durations stay sub 45 seconds (for reference most gym boulders or board problems are often completed in under 30 seconds). For the purposes of this post we’ll stick to single climbs instead of interval training on a macro scale (that’s easily it’s own blog post). Let’s use the same problems we used for the 4x4’s but this time, after climbing problem one, we rest for at least as much time as it took to climb it plus some (you can easily bump all the way to a 1:2 in this instance). By incorporating that little rest period we’ve accomplished two things: 1) the lactic energy system isn’t depleted or run down into the red, and 2) we’ve broken down a rather large block of climbing into more manageable pieces. So back to those original 4x4 problems, with this new rest period incorporated into the structure, now those rounds feel more reasonable. So much so that it’s possible to increase the difficulty of the climbing perhaps?

As stated before, I really don’t believe that one of these circuit protocols is better than the other. That would be like arguing which hangboard routine is “the best” - good luck with that. Probably the most important takeaway from looking at these two methods is this: 4x4’s are training that’s designed to make you fatigued. Interval training is designed to help resist fatigue. When used consistently in a well thought out training program they can both be very beneficial and yield great results. It’s also worth noting (like many training tools) that these warrant athletes trying them both and measuring the outcomes (as best as possible). Athletes will undoubtedly respond differently to these just as they would most any training stimulus.

Which brings us back to my athlete who was certain the 4x4’s made all the difference in their training. I do in fact agree that the 4x4’s helped them break through to that new level. However; some background information is important here. We started that program with the athlete having spent months climbing long multi-pitch routes before the training began, their baseline fitness and overall capacity for work was at its highest levels which gave us a fantastic head start in the training. We began working with interval boulders to increase their ability to climb harder sequences, upping the difficulty of climbing they could do on a consistent basis during climbing sessions. Then towards the end of the program, as the weather turned and the focus shifted to shorter more power endurance sport climbing goals, we transitioned to 4x4’s with a new baseline of climbing difficulty under their belt. The end result was of course a new personal best with the most recent training focus seeming to make the most impact. The catch being there was a significant preparatory or build up phase that led to that breakthrough. The combination of the two methods is ultimately what led to that success.

There are really great resources for implementing these two methods into your climbing. Nearly all SUBSTR8 athletes work with one or both of these in their programs. My colleagues over at Climb Strong have some great modifications of the 4x4 on their website, and earlier this year Neil Gresham did a nice little write up on Interval Training for Climbing magazine. Luckily we have a lot of curious minds in the coaching field and there are some really great variations of these out there to try - I’m particularly fond of the SUBSTR8 Hi-Lo 4x4 (shamelesss plug). If you haven’t incorporated these in your training yet I do recommend them for building your endurance and power endurance bases. Just remember that like all training stimulus, they need to be implemented in a well thought out plan, not just thrown into random sessions.