Understanding the Lactic Energy System

by Steve Bechtel

If you’ve ever climbed to the top of a strenuous route, you’ve felt the burn. If you’ve ever trained super-hard, you’ve felt the debilitating soreness the day after the session. Undoubtedly, you’ve also read or been told that one or both of these is due to lactic acid buildup in your muscles. In this article, I hope to explain why neither of these situations is true, and why lactate production is a useful and an essential part of training hard.

This has always been a confusing subject for me, so I was really pleased to find two great resources that could explain the complexity to a dummy like me: Special Strength Training by Yuri Verhoshansky and Ultimate MMA Conditioning by Joel Jamieson.

In an ideal situation, all of your training would be aerobic. It’s efficient, less fatiguing, and you recover quickly from it. But when things get strenuous, your body isn’t capable of delivering energy quickly enough by aerobic methods alone. Your body has two ways of generating energy beyond the aerobic system. These two systems are the Alactic (or ATP-CP) energy system and the Lactic (or Glycolytic) energy system. Both systems can generate energy much more quickly than aerobic means, but both cause much faster fatigue.  

The Alactic energy system uses fuel present in the muscles themselves and can produce high levels of energy for 10-12 seconds before having to “pass the torch” to the Lactic system. The latter system is capable of being your primary source of energy for around a minute before you have to rest or slow down. Knowing that most routes (and many boulder problems) take more than a minute to climb, it’s important that climbers understand the critical importance of developing each of these systems optimally. Having a properly conditioned lactic system will mean the difference between sending and coming back to redpoint next month.

Lactic Energy Production
In order to understand how muscular fatigue occurs, let’s look a bit at how the lactic system works. Lactic energy production follows a series of chemical steps known as anaerobic glycolysis. The whole thing starts with a molecule of sugar. This molecule is converted to glucose, which is then converted to 2 molecules of pyruvate. The pyruvate can either be used oxidatively (not our concern here) or it can be converted to lactate.

The higher the intensity of workload, the higher the level of lactate in the blood. This initially led scientists to believe that lactic acid was responsible for the pain and fatigue associated with these workloads. We have also learned that any lactate present in the blood during high levels of intensity are all-but-gone within a couple of hours after exercise, showing us that it can’t be lactate that makes us sore. The fault then fell on hydrogen ions, which are also accumulated during intense exercise. Although this theory has also come under fire recently, the take home is the same: lactate is your friend, not your foe.

A great way to look at lactate is as a bridge between anaerobic and aerobic energy production. It can be used within the muscles in which it’s produced or transported to other parts of the body to be used as a source of energy for aerobic metabolism. Climbers, and other athletes who rely heavily on lactate metabolism, we often see accumulations of lactate as much as 50% higher than we see in athletes in aerobic sports. These accumulations reflect the body’s enhanced ability to tolerate intense exercise and do it longer than other athletes. These abilities are termed anaerobic capacity and anaerobic power.

Improving Lactate Metabolism
The balance between the aerobic and anaerobic energy systems is really the balance between anaerobic power and anaerobic capacity. Like I said above, anaerobic power is how quickly you can generate power, anaerobic capacity is how long you can keep it up. This is easily illustrated in your ability to do all the moves on a short route or long problem (anaerobic power) versus linking them (capacity). Improving your capacity is key for boulderers moving into routes, where improving your anaerobic power will allow you to do longer cruxes and sustained sequences.

There is a threshold level where you can no longer sustain high-intensity activity, known as the anaerobic threshold or lactate threshold. This is easily marked by the accumulation of lactate in the blood, though as I said earlier, lactate is not responsible for the fatigue. At anaerobic threshold (AT), the body’s need for energy is simply overwhelming its ability to produce it. Once an athlete is over this line, there are only moments before the intensity of activity has to back off before the athlete has to stop activity altogether.

How does one go about improving these factors, though? The truth is that anaerobic capacity is dependent not only on training in the nauseating and painful world above AT, but also in building sub-maximal endurance just below the threshold. Depending on your specific needs, you’ll need to parcel out your training: if you are doing 10-12 move sequences or problems, then much of your training can be intervals, boulder links, and the like. If you’re doing routes that are more sustained, such as the sport climbs of Indian Creek or the Red River Gorge, you’ll need more time below threshold.

Training for anaerobic capacity causes a few distinct changes in your body’s systems. You’ll see an increase in pH buffering capacity, in the rate of waste product removal, and an increase in the availability of energy substrates. On the other hand, anaerobic power adaptations include increases in the amount or percentage of glycolytic muscle tissue, and increase in glycolytic enzymes, and improvements in “recruitment” or CNS pathways.

There are, of course, limitations to how much you can develop this system. The metabolic pathway involved in anaerobic energy production is significantly less involved than that of the aerobic system, and thus there are fewer qualities we can improve. Science also shows that there is a significant genetic component to your ability to develop power or capacity in this system…some people just don’t have it. Because this system is fairly simple, the potential methods for developing it are limited.

To improve your anaerobic power, you need to do as much work as possible as fast as possible. Improving anaerobic capacity involves working anaerobically for as long as possible each session. Below are a couple of exercises adapted from Jamieson’s great book.

Anaerobic Power Exercises
Lactic Power Intervals – These are performed on a steep bouldering wall or on a continuously overhanging route. Movement has to be continuous and fast, and the problems should lack cruxes or tiny holds. In fact, most climbers will need to start on pretty easy problems with very large holds. Start with 30-40 seconds of hard, fast climbing followed by 3x as much rest (90-120 seconds) Do three repetitions of this, then rest 5-8 minutes. After resting repeat the same protocol for three more sets, resting 5-8 minutes between each. 1-2 days per week during a PE phase. We reduce the volume to once per week during redpointing, and then only if you can’t get to the crag.

These can be done with weights or kettlebells or even running, but remember that anaerobic adaptations are extremely specific to the muscles used in training. As always, climbing is best.

Anaerobic Power Resistance Combos – This method is complex and requires a facility that has a weightroom close to your bouldering wall. We do 30 seconds of sustained anaerobic steady state activity, 30 seconds of total body resistance and finish with a boulder problem. Try to take less than 15 seconds between each exercise. Total work will be about 100-120 seconds, which is followed by 3 minutes rest. Start with 3 rounds of the circuit, rest 8-10 minutes, then do another circuit with different exercises.

Anaerobic Steady State modes:

Airdyne Bike

Battling Ropes

Rowing Machine

Ski Erg



Total Body Resistance Modes:

Power Cleans

Kettlebell Snatches

Hang Power Snatches

Sled Pushing / Dragging

Front Squat / Push Press Combos


Static Dynamics – As strange as the term is, these are actually pretty cool. We tend to use a pull-up bar with a kickboard or chair below it, an inverted row, or a pair of large holds on a system wall. Pull on, do three pulls through a full range of motion, then rest in the straight-arm position for 10 seconds. Repeat this series for 3-6 minutes. Rest (actively – jogging or walking) for 10-15 minutes, then repeat, preferably with a different exercise mode.

To improve anaerobic power, you’ll intensify the exercise by doing more pulls or making the holds worse. For capacity, you would extend the set, or add additional sets to the workout.

Anaerobic Capacity Exercises
Lactic Capacity Intervals – This exercise is similar to the power intervals, but you change the work to rest ratios a bit to force more work time and reduce rest. This method is appropriate for building capacity for long, sustained routes that lack significant cruxes and for building overall day-long power. Training hard for lactic power costs; long endurance and max strength have both been shown to decline when training is focused on lactic capacity. We use the same methods as outlined for Power Intervals, a 30-45 degree wall or route.

For these intervals, you’ll climb for 1.5 to 2 minutes non-stop, and I mean non-stop. Rest is decreased to be exactly as long as the climbing takes. Do four repetitions of this, then rest 5 minutes before starting the next set. Do 2-5 sets per workout.

Anaerobic Capacity Resistance Combos – These are exactly like the power combos, except we change the work to rest ratio and the workout volume. Each exercise in the circuit is performed for 45 to 60 seconds (for a total of 3-3.5 minutes per circuit), and you rest just 60-90 seconds between efforts. Do three circuits, rest 5-7 minutes, then do three more with different exercises if you like.

Yes, there’s more to life than just getting pumped. Although your ability to improve your anaerobic fitness is fairly limited, it can be done. And if you’re going to bother to train this energy system, you might as well get something out of it.