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## Compensatory Acceleration Training

Andy Bolton (pictured below), the first person to deadlift 1,000lbs, and Dr. Fred Hatfield, one of the first people to squat 1,000lbs, both describe a similar phenomenon they use in their training. They both accelerate throughout the lift. Dr. Hatfield calls this method compensatory acceleration training. This method seems to work for them, so it can probably help many others.

## What is Compensatory Acceleration Training?

Compensatory acceleration training involves trying to move the weight as quickly as possible throughout the lift. If we take the simple equation of force = mass x acceleration, the more we accelerate, then the more force we can put into a movement. Thus, we need to move light weight quickly in order to equal the force we put into moving heavy weight.

Here is Dr. Hatfield’s description:

If you’re applying a thousand pounds of force at the bottom of the lift and then as leverage improves you continue to apply a thousand pounds or less, you’re not accomplishing as much as you can. Instead, you’ll see that as leverage improves you’re able to apply twelve hundred pounds of force, fourteen hundred pounds of force up near the top. The secret though is that you’re applying as much force as you possibly can exert all the way through the lift. That means you’re spending more time under maximum tension. That means you’re going to make progress much faster than you could otherwise, probably twice as fast.

Applying this training to the squat would mean that you start out slow at the bottom of the movement (where the leverage is not as good) and you speed up as you move up the movement. If the weight is light enough, your speed will actually throw the bar up in the air at the top. With the deadlift, the acceleration at the top will shoot the bar outward.

Andy Bolton completes this speed work after his heavier training. In a recent seminar, he told a story about a person who wanted to follow Andy’s routines. This person did the same or above the same weight in each of his own workouts. However, when the competition came, the other lifter could not do as much as Andy. What it came down to was not how much this other person lifted in training, but the way he lifted the weights. This other lifter did not accelerate through the movements like Andy.

In addition to Andy Bolton and Dr. Hatfield’s world records, there has also been a great deal of research showing the benefits of this type of training.

## Modifications to Compensatory Acceleration Training

One difficulty with this type of training is the continued movement of the bar after the lift has been finished (especially at lower weights). The bar flying off the body could cause injuries. Dr. Hatfield suggests learning to slow the lift down at the very end of the lift.

Another modification to the method, popularized by Louie Simmons at Westside Barbell, is to use bands and chains on the bar. A band will exert the most force at the end of the lift. Thus, the lifter must accelerate to overcome the resistance of the band. Chains are similar in that more resistance is encountered when more links of the chain are off the ground (a future article will discuss using chains and other types of resistance in greater detail).

## Take Home

In general, it is a good idea to incorporate explosiveness in any strength training. Dr. Hatfield suggests:

Most guys I know are content to squat down and really strain hard to get up through that sticking point and then back off and then coast to the top and I’m saying you’re wasting your time. First of all, you should be applying maximum force through the entire range of motion; maximum force.

References:

1. González-Badillo JJ., Rodríguez-Rosell D., et al. “Maximal Intended Velocity Training Induces Greater Gains in Bench Press Performance than Deliberately Slower Half-Velocity Training.” European Journal of Sport Science 0 (0): 1–10 doi:10.1080/17461391.2014.905987.

2. Hatfield, FC., Power: A Scientific Approach. 1989. 1st edition. Chicago: McGraw-Hill.

3. Swinton, PA., Lloyd, R. et al. “Contemporary Training Practices in Elite British Powerlifters: Survey Results From an International Competition.” Journal of Strength and Conditioning Research 23 (2): 380–84. doi:10.1519/JSC.0b013e31819424bd.

## How To Do Your First Pull-Up.

I have a rule when working with new athletes on pull-ups. I ask them to “just say no” to bands. Bands are much like drugs in that once a person gets hooked, it is difficult to get them off.

You may have inadvertently gotten yourself hooked on these little strips of rubber with the best of intentions. But I’m going to explain the three reasons you need to break this habit, and how doing so will help you and your pull-ups be stronger.

## Bands Provide Inconsistent Assistance

The intent of banded pull-ups is a good one. It provides assistance to the athlete so he or she can get the chin or chest to the bar. It is a cheap alternative to the expensive machine that provides a counterweight applied to the person’s legs or knees to assist him or her (sometimes called a Gravitron machine). But as the cliché goes, you get what you pay for.

The banded pull-up is like a spotter that is sometimes overly attentive and at other times not paying attention at all. Imagine someone spotting you on a bench press and at the bottom position, he yanks on the bar for you. At the top position, he is off checking his phone. The banded pull-up is similar in how it assists people.

## The Solution – Get a Spotter

If you want to perform assisted pull-ups, get a spotter. A spotter will be able to provide more optimal assistance by giving you enough assistance in your sticky spots so you can finish the movement and gain strength. In many group classes, it might be difficult to have spotters, but a team workout where one member is working and the other is spotting could be an alternative.

## Bands Should Only Complement the Resistance Curve

In compensatory acceleration training of the squat, the athlete uses bands attached to the ground to provide greater resistance in the top part of the exercise where the movement is easier. With this technique, we learn to accelerate through our lifts, which helps us lift heavier things. In banded pull-ups, we are doing the opposite by giving assistance in all the wrong places.

The bottom of the pull-up is where we need to start from a dead stop. We have no momentum and our leverage is at its worst. Sounds like a perfect place to help, right? Well, yes – but only if you don’t want to build strength. The places we struggle are where we build the most strength. The bottom of a banded pull-up is like a jumping device for babies. It might be entertaining and fun, but it is not the optimal way to build strength.

Many people are as happy as infants when they start doing banded pull-ups. But you should treat them like a highly addictive drug and stay away.

## The Solution – Do Jumping Pull Ups

You can break through strength plateaus by getting stuck in the toughest positions. We do box squats to practice being stuck in the bottom. Thus, I would suggest jumping pull-ups, which simply involve jumping up on the bar and slowly lowering yourself down. The key is in resisting on the way down.

### “A more advanced person could do pauses at his or her sticky points. This controlled and slow descent will build pull up strength much faster than bands.”

In a workout, you can figure out how long each descent should be and shoot for time on the way down as the goal (e.g., each round will have five reps of two seconds on the way down). Don’t count reps where you don’t hold for the specified time. It will be much better for you in the long run if you don’t rush on the way down. A more advanced person could do pauses at his or her sticky points. This controlled and slow descent will build pull up strength much faster than bands.

## Get Rid of the Bands

The third reason is a sub-reason of the last one. If you are not creating strength in the right part of the strength curve, then you will have a difficult time getting off bands. The idea is that a person will progress from heavier to lighter bands. However, this progression seems to move too slowly and see people doing banded push-ups for years. For the majority of people, we can often get their first pull-up within a month with the proper training.

## The Solution – Grease the Groove

As a person attempting your first pull up, more volume can be helpful. A greasing-the-groove type of program might be perfect for some. Every hour or so, do a few jumping pull-ups with a slow descent. If you can’t do them throughout the day, do them every day. A low daily volume over frequent days adds up to impressive gains.

## Ring Rows Are a Better Alternative for Beginners

Ring rows are great for a beginning athlete. The movement is easily scaled by moving the feet forward or backward and/or bending the knees.

In many aspects of CrossFit and other conditioning programs, we do a lot of pressing movements (overhead presses, bench press, push ups). The pull up winds up being one of our only pulling movements. The pull up is great, but it is also good to change the angle of the pull to build up the muscles of the back, the rotator cuff, and around the scapula. I recommend ring rows or some type of bent-over row for everyone in order to create balance in muscular development and to support shoulder health.

Another similar option is to place a bar in the rack. You can then do pull ups with your feet outstretched in front to provide assistance (i.e., a nice tight plank with the feet taking away some of the weight of the body).

## Wrap Up

As the saying goes (I may have it slightly wrong), friends don’t let friends do banded pull-ups. Bands are like drugs. Please don’t get hooked on them.

The only time a band would be appropriate is if the bands are attached to something on the floor and providing resistance. That is a great use of bands as it gives the most resistance at the top of the movement and teaches explosiveness on the way up.

But if your goal is to build strength for strict pull-ups, I recommend ring rows and jumping pull-ups with slow descents. These exercises will build strength much more quickly for the pull-up.

## HIRT for Hypertrophy

The program below is a byproduct of a strength-endurance protocol for athletes that I worked on with strength coach Pavel Tsatsouline. Trainees who used the program routinely complained about their clothing no longer fitting properly: their shoulders got bigger and their waist sizes got smaller.

### Myofibrillar vs. Sarcoplasmic Hypertrophy

Myofibrillar hypertrophy is the growth of muscle contractile parts, specifically actin and myosin. They equate to strength, speed, and a “functional” type of muscle growth. It’s the muscle of a lean African leopard and it’s what you see in elite sprinters, boxers, and gymnasts.

It stands in stark contrast to sarcoplasmic hypertrophy, which is the increase of plasma, organelles, and non-contractile proteins with no increase in strength. You can think of water-injected chicken breast at the supermarket as an example of sarcoplasmic hypertrophy.

In contrast to most bodybuilding programs, the one presented below details a 6-week protocol that concentrates on lean, striated myofibrilliar hypertrophy while burning fat and building the type of endurance needed to carry 160-pound kegs up multiple sets of stairs (as Dr. Fred Hatfield described it).

### The Myofibrillar Hypertrophy & Conditioning Program

Here’s a quick overview, then we’ll break down the training and dig into the science behind it.

This program consists primarily of heavy kettlebell swings and double kettlebell presses. Do this 3 days per week:

#### Kettlebell Swings

Complete 25 heavy kettlebell swings (40-48kg for strong gentlemen; 20-24kg for strong ladies).

These swings should be as powerful as possible. If you lose form or more than 10% of your power, you’ve chosen the wrong weight. You need to fight to the end without looking like you’re fighting to the end. Once completed, briefly catch your breath (for two minutes) and do the next series of exercises.

#### Double Kettlebell (or Dumbbell) Presses

Do 3 sets over a 10-minute period. You want your presses to be crisp and powerful. Don’t grind out reps. Instead, go grab a lighter weight or take more rest.

• 2 minutes after doing kettlebell swings: 7-8 reps of presses at 65% of 1RM
• 4 minutes after doing kettlebell swings: 2-3 reps of presses at 85% of 1RM
• 7 minutes after doing kettlebell swings: 5-6 reps of presses at 75% of 1RM
• Rest for two minutes. You are now done with  one series. Repeat this series two to four more times, depending on the day of the week.
• Monday: Go through the series 3 times (75 total swings and about 45 presses).
• Wednesday: Go through the series 5 times.
• Friday: Go through the series 4 times.

### Program Notes

• On other weight training days, work abs, squats, and upper-body pulls. There’s no need to train lower body pulls or upper-body presses as you’re already getting plenty of volume on those movements. If you’re an endurance athlete, you can also train long, slow distances, but in general, avoid other glycolytic, burn-types of exercises while on this program.
• Maintain this program for 6 weeks. It should be cycled every 3 months at most.

### The Science Behind This Program

The general goal is to drain the ATP stores from our system as quickly as possible. That’s why we need maximum effort on every set. When we use up our ATP, our body initiates a complex mechanism that starts building new mitochondria, which builds more endurance.

To be more specific, by using our ATP, we trigger AMPK, which signals the need for more mitochondria and better endurance. (While research on long, slow, endurance training has shown AMPK to inhibit mTOR, which regulates, among other things, cellular growth, it’s not the case with this style of training.)

### Grow the Muscles

Pushing sets over 15 seconds leads to a big increase in the acidic environment as the glycolytic system kicks in to create more ATP. We can use this acidic rest period to trigger hypertrophy because it allows us to maximally utilize the hormone system to create body composition changes.

### Train Like Sprinters

This protocol uses high-intensity repeat training (HIRT). The key difference between HIRT and HIIT is that we repeat each high-level performance, whereas interval training builds up fatigue and leads to declining performance over the intervals. In our protocols, we want 90% power across the complete set with no decline over time.

In HIIT training, the rest interval is short and the build-up of acid reduces performance over each accumulating set. In our repeat training protocol, we wait ten minutes between doing our sets of kettlebell swings, which take about 20 seconds.

This type of training is similar to what sprinting coach Charlie Francis did. He wanted every sprint to be perfect, so he needed the ATP system to be fully replenished before the next set. His training started with 10 minutes of rest between the first set and the second, but the rest increased over the course of the training session.

### Putting the Science Together

By providing enough rest between sets, we optimize power for every rep. When we’re powerful on each rep, we optimize our genetic ability to convert type IIX fibers (fast-twitch glycolytic). We might not all be built to be lean, athletic sprinters, but we can get as close to our genetic limits as possible.

We also reap the benefit of an acidic environment by doing power sets that last over 20 seconds, which, when followed by the double kettlebell presses, leads to muscular growth. (Our first few studies on this type of protocol were quite successful to that end, but we’re undertaking a more formal research protocol with more control.)

### Program Variations

I don’t care if you become bored with this protocol. Your boredom isn’t related to the results. However, if you’re unable to do powerful swings or lack suitable shoulder mobility for presses, I can offer a few variations.

For the endurance portion, we need an exercise that taps into maximum power. I recommend sled pushes or uphill sprints instead of sprints. These will help you find your power sweet spot. However, you don’t want to push the sled as fast as you can, nor do you want to push it slowly.

Power will optimize both speed and strength. Finding your maximum power will provide the training stimulus needed to maintain maximum effort for 20 seconds.

For the upper body, double kettlebell presses are a great overall movement, but you can do landmine presses if you don’t have the proper shoulder mobility. Pull-ups are also an option. Power is also important here, so you don’t want to grind out reps.

### References

1. Burgomaster, K. A., Heigenhauser, G. J., & Gibala, M. J. (2006). “Effect of short-term sprint interval training on human skeletal muscle carbohydrate metabolism during exercise and time-trial performance,” Journal of Applied Physiology, 100 (6), 2041-2047.
2. Burgomaster, K. A., Howarth, K. R., Phillips, S. M., Rakobowchuk, M., MacDonald, M. J., McGee, S. L., & Gibala, M. J. (2008). “Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans,” The Journal of Physiology, 586(1), 151-160.
3. Gibala, M. J., Little, J. P., Van Essen, M., Wilkin, G. P., Burgomaster, K. A., Safdar, A., … Tarnopolsky, M. A. (2006). “Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance,” The Journal of Physiology, 575(3), 901-911.
4. Lo, M.-C., Lu, C.-I., Chen, M.-H., Chen, C.-D., Lee, H.-M., & Kao, S.-H. (2010). “Glycoxidative stress-induced mitophagy modulates mitochondrial fates,” Annals of the New York Academy of Sciences, 1201, 1-7.
5. López-Lluch, G., Irusta, P. M., Navas, P., & de Cabo, R. (2008). “Mitochondrial biogenesis and healthy aging,” Experimental Gerontology, 43(9), 813-819.
6. Fiorenza, M., Gunnarsson, T. P., Hostrup, M., Iaia, F. M., Schena, F., Pilegaard, H., & Bangsbo, J. (2018). “Metabolic stress-dependent regulation of the mitochondrial biogenic molecular response to high-intensity exercise in human skeletal muscle,” The Journal of Physiology, 596(14), 2823-2840.

## HIIT versus HIRT

Your feelings don’t matter! That is, your subjective feeling of the effectiveness of a workout is not important as what science tells us is important to building an impressive base of endurance and changing your body composition. A common training method is high-intensity interval training (HIIT).

This type of training leaves people on the floor in a pool of sweat feeling as if they have accomplished a great workout. In this article, I propose a smarter way of training, which should have a greater effect on endurance and long-term body composition effects. This high-intensity repeat training (HIRT) may not ‘feel’ as good, but your feelings don’t matter.

## History of HIIT

Interval training with high intensities has been around for years. The tipping point of HIIT seems to have come with the research of Dr. Izumi Tabata. In the early 1990s, he collaborated with Irisawa Koichi, the Japanese speed skating team coach who had developed a protocol of short maximum bursts of sprints followed by short periods of rest. These short maximum burst improved and maintained peak performance in elite speed skating athletes. Tabata wanted to test the protocol with athletes at different levels.

The initial Tabata paper from 1996 examined two groups of amateur athletic males in their mid-twenties:

1. The first group pedaled on an ergometer for sixty minutes at moderate intensity (70% of VO2 max). Similar to a long jogging session or what has been termed long slow distance (LSD) work.
2. The second group pedaled for 20 seconds, followed by 10 seconds of rest, for 4 minutes (completing 7 to 8 sets total) at maximal effort. The key phrase is maximal effort, as each interval was expected to be a sprint. If athletes could not keep up the speed requirements, they were stopped at 7 sets.

Both groups trained for 5 days a week for a grand total of 5 hours a week or 20 minutes. The protocol lasted for 6 weeks.

In the above figure, the graph on the right shows anaerobic progress. As expected, the Tabata-style sprinting group improved their performance while the long-duration group did not. These results make sense given that the sprints use a lot more anaerobic processes.

The graph on the left shows the results of oxygen uptake, which is a measure of how efficient people are at aerobic activities (the more oxygen we can take in, the more efficient our aerobic processes will be). Both groups improved on this measure in similar fashions (the red line shows the Tabata-style maximal-effort group).

This result was expected for the long-duration group as they were specifically training for this goal. The result for the group doing sprints was surprising in that they improved in a similar fashion. Thus, it seems that a four-minute maximal intensity Tabata workout had the same aerobic benefits as doing a sixty-minute moderate intensity workout. This news was pretty shocking in that you could get two-in-one benefits from only a four-minute workout. The HIIT revolution had begun.

Tabata Velergometer

## Potential Issues with HIIT

Maximal-effort sprint-like activities are a key component for Tabata workouts. Many people have difficulties maintaining maximum effort for 20 seconds over seven series. Thus, very few people actually do a Tabata style workout. There are many “Tabata-inspired” workouts that last from 20 minutes to 60 minutes. These bastardizations of Tabata protocols often lead to decreased effort on each interval.

Tabata style protocols have been shown to be beneficial in the short-term. The high stress on the body can cause it to adapt by getting rid of poorly functioning mitochondria (mitophagy) and replacing them. Issues arise when people attempt it for long periods of time. The high stress from these workouts can have detrimental effects in the long-term with degradation of mitochondria. Too much of a good thing becomes a bad thing (Ramos-Filho 2015).

## Burgomaster and Gibala Intervals

Kirsten Burgomaster and Martin Gibala have modified Tabata’s maximal effort protocols. The big difference in their protocols from Tabata is that they allow for longer rest (4 minutes), but also longer work intervals (30 seconds of maximum effort).

Similar to Tabata’s original research, Burgomaster and Gibala have found benefits to aerobic and anaerobic systems. Others have found benefits in fat loss (here is a good review article). Four minutes of rest allows for more time for our ATP and creatine phosphate system to recover and may provide better performance on the maximal effort attempts.

A major benefit of Burgomaster and Gibala intervals is that it activates the AMPK pathway that is responsible for mitochondrial enhancement. In a nutshell, when we quickly deplete our ATP stores, we create ADP and AMP (each iteration having one less phosphate molecule; from triphosphate to diphosphate, to monophosphate). Our body uses the ATP/AMP ratio to signal AMPK, which then leads to more mitochondria to process the extreme energy demands5.

#### ATP -> ADP + energy -> AMP + energy

A single 30-second sprint increases the AMP/ATP ratio by as much as 21 times. However, we are walking a fine line between mitochondrial growth and ripping out the framework of our energy system. Once we get down to AMP, we can rip off the last phosphate and the whole structure breaks apart. We no longer have a structure to add phosphates.

Some of the biggest damage from a heart attack comes after oxygen returns to the heart (Emerling, 2009). The heart has used up all of the phosphate and the mitochondria start making free radicals as there are not enough adenosine ribose frames to accept phosphate molecules. With too long of intense training, we actually start making ammonia as the AMP molecule is broken down.

Timing is important. The longer rest of Gibala and Brugomaster’s protocols is nice, but for some athletes, we might be causing too much damage to the adenosine molecules going for 30-second intervals. We might improve upon these protocols by shortening the work intervals, which allows us to recover quicker and to not bring about as much lactic acid.

## High-Intensity Repeat Training (HIRT)

Interval training is differentiated from repeats by when the recovery occurs. In interval training, the recovery is incomplete, so the next interval starts when the person is already fatigued. This incomplete recovery leads to a decline in performance after each interval. Repeats maintain the same high level of performance over time. Gibala and Burgomaster’s work would likely qualify as repeats as participants recover enough between sets to do the training again.

HIRT reduces long-term stress on the body that comes from HIIT training. The key component of HIRT is to maintain effort and power on each and every repeat. Charlie Francis, coach to many Olympic world-record holding sprinters, was known to maximize rest intervals so each sprint could be better or at least the same as the sprint before. Rest was vital so that people could ‘repeat’ their performance, not watch it degrade.

The important part of repeat training is to be able to perform at maximal intensity each time. Another example is to work around 10 seconds or less, so that recovery can occur much quicker. An example would be doing ten kettlebell swings every minute on the minute for about 10 minutes. The key is to have maximum power on each and every set. A potential way to make sure one is maximizing power is to use an accelerometer.

## Summary

There are some key components to HIRT:

• The first component is built right into high-intensity repeat training name. The person must be able to repeat the high-intensity performance. If it can’t be repeated, then the training session should end or more rest is needed.
• Intensity is key. The goal is to practice the exercises with maximal intensity for a short duration of time. Don’t worry about your feelings of guilt for not training longer. Doing more than the specified sets will not help you in the long run.
• Work duration should be between 5 to 15 seconds. Longer time intervals will lead to decreased performance and the need for longer rest (Gibala needs 4 minutes of rest for 30 seconds of work). Keeping the work time short allows for maximum effort and quicker repeat performance.
• Luxurious rest intervals are needed. For 10 seconds of work, there should be about 45 seconds of rest. Training in every minute on the minute fashion works well for 10 seconds of intense work.
• Pick exercises with less risk of injury and the ability to maintain maximum power. Sprinting form is a difficulty for many people. Furthermore, the power in a sprint can only be maximized for the first few seconds of the sprint (then the maintenance or stopping of deceleration is what is important). Sled pushes or pedaling an exercise bike are better and probably safer for a sedentary athlete. Rowers or swimming are also good alternatives. For advanced athletes with the ability to swing or snatch a kettlebell explosively, the snatch and swing work well. The key is the ability to do it with maximum power.
• Volume varies depending on goals. If your goal is maximal strength, then doing HIRT workout one to two times a week might be beneficial. If your goal is to build greater endurance, then four to five days a week will be most beneficial.
• Separate strength from conditioning. Do not think HIRT as a way to build strength. You must be strong first.

## A Sample Protocol

Combining the above components we can create an example protocol. Load a sled so that you can move fast (hill sprints would work too). Sprint for 8 seconds as far as possible. Measure the distance after each push and maintain it. Do one set every minute for 4 to 10 sets (vary the volume each session by doing low medium and high volume days). If you can’t maintain the distance, the training session is complete and you need to add more rest to your next training session.

References:

1. Boutcher, S. H. (2010). “High-Intensity Intermittent Exercise and Fat Loss.” Journal of Obesity, 2011, e868305. doi:10.1155/2011/868305

2. Burgomaster, K. A., Heigenhauser, G. J., & Gibala, M. J. (2006). “Effect of short-term sprint interval training on human skeletal muscle carbohydrate metabolism during exercise and time-trial performance.” Journal of Applied Physiology, 100 (6), 2041–2047.

3. Burgomaster, K. A., Howarth, K. R., Phillips, S. M., Rakobowchuk, M., MacDonald, M. J., McGee, S. L., & Gibala, M. J. (2008). “Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans.” The Journal of Physiology, 586(1), 151–160.

4. Emerling, B. M., Weinberg, F., Snyder, C., Burgess, Z., Mutlu, G. M., Viollet, B., … Chandel, N. S. (2009). Hypoxic activation of AMPK is dependent on mitochondrial ROS but independent of an increase in AMP/ATP ratio. Free Radical Biology and Medicine, 46(10), 1386–1391.

5. Hardie, D. G. (2003). Minireview: The AMP-Activated Protein Kinase Cascade: The Key Sensor of Cellular Energy Status. Endocrinology, 144(12), 5179–5183.

6. Hardie, D. G., Ross, F. A., & Hawley, S. A. (2012). AMPK: a nutrient and energy sensor that maintains energy homeostasis. Nature Reviews Molecular Cell Biology, 13(4), 251–262.

7. Gibala, M. J., Little, J. P., Van Essen, M., Wilkin, G. P., Burgomaster, K. A., Safdar, A., … Tarnopolsky, M. A. (2006). “Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance.” The Journal of Physiology, 575(3), 901–911.

8. Kahn, B. B., Alquier, T., Carling, D., & Hardie, D. G. (2005). AMP-activated protein kinase: Ancient energy gauge provides clues to modern understanding of metabolism. Cell Metabolism, 1(1), 15–25.

9. Medbo, J. I., & Tabata, I. (1989). “Relative importance of aerobic and anaerobic energy release during short-lasting exhausting bicycle exercise.” Journal of Applied Physiology, 67(5), 1881–1886.

10. Ramos-Filho, D., Chicaybam, G., de-Souza-Ferreira, E., Martinez, C. G., Kurtenbach, E., Casimiro-Lopes, G., & Galina, A. (2015). High Intensity Interval Training (HIIT) Induces Specific Changes in Respiration and Electron Leakage in the Mitochondria of Different Rat Skeletal Muscles. PLOS ONE, 10(6), e0131766.

11. Tabata, I., Irisawa, K., Kouzaki, M., Nishimura, K., Ogita, F., & Miyachi, M. (1997). “Metabolic profile of high intensity intermittent exercises.” Medicine and Science in Sports and Exercise, 29(3), 390–395.

12. Tabata, I., Nishimura, K., Kouzaki, M., Hirai, Y., Ogita, F., Miyachi, M., & Yamamoto, K. (1996). “Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max.” Medicine and Science in Sports and Exercise, 28(10), 1327–1330.

## Effective Ways of Building Mitochondria

Why does exercise make us healthier? One of the most important linkages may be due to improving our mitochondrial functioning. Healthier mitochondria may be the route to living better, healthier lives, while also being better in our sport or work.

This article is the first in a series breaking down current research and how you can apply it to your goals. Here, we cover mitochondrial biogenesis (building more mitochondria) using different types of sprints and rest intervals, as well as long slow endurance types of exercise protocols.

Fiorenza and colleagues (2018) published a study of how athletes can improve their mitochondrial functioning. Mitochondria are important as they convert carbohydrates, fat, and protein into ATP and other energy currencies. Mitochondrial functioning is related to many processes in aging and disease, as well as our ability to perform speed, power, and endurance types of exercise. Thus, by learning the mechanisms and optimizing this process, we can live better, healthier lives, while also being better in our sport or work.

Before we get into the details of the study, let me define some terms.

PGC-1α—Key regulator in making more mitochondria (mitochondrial biogenesis).

AMPK, CaMKII, and p38 MAPK—These are all thought to be factors that bring about more PGC-1α.

Adenosine Triphosphate (ATP)—ATP is our primary source of energy. Muscles use ATP to contract by decoupling one phosphate molecule, which creates adenosine diphosphate (ADP; or with two phosphates). When the system breaks down ADP we get one phosphate or adenosine monophosphate (AMP). The ratio of AMP:ATP is thought to activate the signaling for AMPK.

Summary of terms—The faster we burn through energy, the more our AMP:ATP ratio changes, which signals AMPK and then PGC-1α. Sprints drain ATP quickly, while long-slow distance also drains ATP to increase mitochondria through this pathway.

## Details of the Study

Participants were experienced cyclists with over 6 years of experience and higher than average VO2 max values (average was 61.9). The researchers wanted to use experienced athletes as unexperienced athletes can undergo many adaptive changes from any training program. The participants were split into three groups: repeated-sprint (RS), speed endurance (SE), or continuous exercise at moderate intensity (CM).

• Repeated Sprints (RS)—These participants sprinted for 5 seconds with an all-out effort. They were then allowed 30 seconds of recovery before the next sprint. They did 18 sprints in total. Thus, they did 90 seconds of total work at maximal effort.

• Speed Endurance (SE)—These participants did 20 second all-out sprints followed by 2 minutes of rest. They did 6 sprints in total. This group did 120 seconds of total work.

• Continuous Moderate Exercise (CM)—This group did 50 min of continuous exercise at a relative intensity corresponding to 70% of their VO2 max. This group did the more traditional long slow distance style of work.

The researchers took blood samples and muscle biopsies before and after the exercise protocols. The RS and SE protocols are not high-intensity interval training as they had adequate rest in between sets for recovery. Traditional interval training shows a decline in performance over time. This research used repeat training where there is little to no decline over time as the rest allows for recovery.

## Results

The study focused on muscular and changes in the blood. Gibala and colleagues (2006) have already shown the 20-second interval leads to V02 max changes. All groups had significant increases in signaling molecules of AMPK and p38 MAPK. The repeated sprint group and strength endurance groups saw improvement on CaMKII. CaMKII affects PGC-1α but also affects the growth of type IIa muscle fibers (Rose et al. 2007). Thus, it makes sense that the 20-second intervals led to the highest amount of CaMKII.

The main outcome we are interested in is the PGC-1α as it triggers mitochondrial biogenesis. The 50-minute moderate exercise group showed the greatest improvement in PGC-1α. While the 20-second interval group had a greater increase over the 5-second sprint group. All groups significantly changed above where they started. Thus, they all had improvements in the signaling of mitochondrial biogenesis.

## Summary

Short sprints of 5-seconds, longer sprints of 20-seconds, and continuous long slow distance of 50 minutes all improved one of the major signaling molecules of mitochondrial biogenesis (PGC-1α). Athletes who cycled for 50 minutes had the greatest improvement. However, the amount of work completed indicates that shorter sprints might be more efficient (90 seconds of total work for the 5-second sprint group and 120 seconds total work for the 20-second sprint group).

One missing component is work intervals between 5-seconds and 20-seconds. We know that ATP is depleted around 50% at around 8 seconds of maximal effort. At about 20 seconds, ATP is depleted to about 10% of its initial level. Between 5 seconds and 20 seconds might be a sweet spot for depleting ATP, increasing AMP, and henceforth increasing AMPK signaling and mitochondrial biogenesis.

## References

Fiorenza, M., Gunnarsson, T. P., Hostrup, M., Iaia, F. M., Schena, F., Pilegaard, H., & Bangsbo, J. (2018). Metabolic stress-dependent regulation of the mitochondrial biogenic molecular response to high-intensity exercise in human skeletal muscle. The Journal of Physiology, 596(14), 2823–2840.

Gibala MJ, Little JP, van Essen M, Wilkin GP, Burgomaster KA, Safdar A, Raha S & Tarnopolsky MA (2006). Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. J Physiol 575, 901–911.

Rose, A. J., Frøsig, C., Kiens, B., Wojtaszewski, J. F. P., & Richter, E. A. (2007). Effect of endurance exercise training on Ca2+ calmodulin-dependent protein kinase II expression and signaling in skeletal muscle of humans. The Journal of Physiology, 583(Pt 2), 785–795.