What is in this article:
Exploration of the impact of fatigue on lifting performance
Basic Principles of post-metcon lifting
Training recommendations for building strength when tired
In previous blogs we’ve discussed the multi-faceted nature of strength. Specifically in the article: Heavy Squats are Not Always the Answer I introduced the idea that strength is context specific. What I mean by “context specific” is that strength is not something that you have, but rather something that must be expressed. The ability to “be strong” at any given moment is dependent on two primary factors:
The nature of the strength test
The environment the test is performed in
rested & ready to go
pre-fatigued (post-metcon / barbell ladder)
training versus competition environment
All of these factors together influence your ability to reach your strength potential in a given test.
Strength in Sport
With the exception of purely strength-dependent sports like Weightlifting and Powerlifting, strength is rarely tested in a rested & ready environment. The CrossFit Open, for example, requires high degrees of strength development in order to complete the tests. However, one rep max strength has only been tested in a fatigued environment. Running some stats on athletes’ lifting under fatigue, using the Open as our data-set, it appears that there is: (1) a lot of variation between athletes in their ability to express their strength under fatigue relative to their reported 1RM’s and (2) the nature of the test can have a dramatic influence on the percentage of 1RM that athletes’ can hit. As an example most athletes were closer to their reported 1RM’s in Open 15.1a versus Open 18.2a. This is likely a result of a more potent pre-fatiguing stimulus in Open 18.1 versus Open 15.1 as we will explore below.
Principles for Pre-Fatigued Strength
In order to begin exploring how we might optimize an athlete’s ability to express strength under fatigue we must understand some basic principles.
Muscles produce less force in a pre-fatigued environment. This is an inherent property of muscles and not something that we can work around or “grind our way through”. Regardless of how well designed our strength training protocols are, the maximal force production capacity of a fatigued muscle is less than in a rested & ready state.
Maximal force production is impacted by prior fatigue more than rate of force development. What this means is that absolute strength will be relatively lower than absolute speed when fatigued. Note: this also informs our training methods for developing strength under fatigue as you will see in the next section.
The type and degree of pre-fatiguing stimulus determines the “ceiling” for subsequent lifting performance. If we express fatigued-strength as a percentage of rested & ready strength then the more severe and intense the pre-fatigue stimulus the lower the percentage we can expect to hit in that test. In other words: the “harder” the workout the less you can expect to lift.
Coordination is impacted by both peripheral (local) and central fatigue. This means that you must develop the coordination to move well under fatigue for complex lifts like the snatch or clean & jerk AND develop your ability to handle the required loads. Skill and strength in the fatigued environment are both prerequisites for successful lifting.
Applying the Principles
It should be clear now that an athlete who wants to be able to express a high percentage of their strength potential under fatigue needs to train their lifts in a similar environment to competition. Applying the principles laid out above I’ve come up with the following general training recommendations. More specific recommendations and example protocols will be included in upcoming content in the Classroom.
Since rate of force development (speed) is less impacted by pre-fatigue, use methods that preferentially develop this strength quality. Improving speed can have positive transfer to both strength-speed and absolute-strength particularly under fatigue.
Develop coordination and skill under fatigue with submaximal Olympic Lifting. Weightlifters often spend extensive amounts of time developing their “feel” for the lifts at moderate percentages (65-75%). CrossFitters can draw from this by performing EMOM or cluster work in those percentage ranges after a pre-fatiguing metcon. Keep in mind that this will not likely improve the athlete’s 1RM but can play a huge role in improving their consistency lifting under fatigue.
Absolute strength can and should be trained in the environment it is tested in the sport. For athletes who have already developed absolute strength levels required to be competitive, a portion of their absolute strength work can be positioned in a post-metcon environment. I’m not sure at this point I’d recommend that this be done all year long, but for a period leading into competition this is likely a necessary training tool. Be particularly mindful of trunk stiffness training under fatigue. The diaphragm(s) function as spinal stabilizers, athletes need to be able to brace their spine even when these structures are fatigued due to high respiration rates.
Designing Pre-fatiguing Metcons
Finally I wanted to provide some notes on creating the pre-fatiguing stimulus. As I discussed in the 15.1a and 18.2a example and Principle-3 above the severity and type of pre-fatigue can play a role in the athlete’s ability to express strength. As a coach with an exercise-physiology background I like to categorize things in order to help make sense of them - and as such I’ve attempted to categorize the types of fatigue and how they impact subsequent strength performance below.
Short & Fast (high metabolite production / low final SMO2)
Good examples of these types of workout would include Open 18.1 and the most recent International Online Qualifier final workout #5 (21-15-9 Thruster / Row / Burpee). For elite level athletes these workouts have no real bottleneck and allow them to maintain extremely high power-outputs. The result is a massive accumulation of metabolite and plummeting SMO2 levels. These types of workouts likely have the biggest impact on subsequent strength performance by impacting everything from cellular signaling to nervous system coordination. The potential to express high degrees of the athletes rested & ready strength after these events is lower than anything else I’ve observed to date.
Longer Endurance (lower metabolite production / high CNS fatigue)
Examples of this might include a 5k Run time trial followed by a max lift or something long and rhythmic like Murph for an advanced CrossFitter. The biggest impact on the ability to express strength from these types of events is a dampening of central nervous system drive. Specifically a reduction in what is known as motor command or the strength of the signal sent from the brain to the muscle. Contrary to popular opinion, CNS fatigue is greatest after longer “endurance” style training or competition than it is after heavy lifting. Assuming that athletes have the ability to “ramp up” before they lift, the impact of this type of pre-fatigue stimulus will be less than that of short & fast workouts.
Local Fatigue (grip blasters & barbell ladders)
A great example of this type of pre-fatigue test is TTT Throwdown workout #20 . I constructed this workout specifically to tax the athletes grip immediately prior to testing a hang clean (grip!). This can also be seen in workouts like the squat clean ladder in 19.2 where one muscle group (quads) gets hammered on for the duration of the workout. The result is that the localized fatigue can wreak havoc on the athlete’s sensation of effort, making submaximal loads feel like 1RM’s. From my perspective, lifting well with a “smoked grip” or “tired legs” comes down to having a bank of experience with those sensations, developed consistently in training.
In the end, getting stronger under fatigue can be even more complex than process of getting stronger rested & ready. It requires the coach to analyze multiple factors including the athlete’s 1RM’s relative to the field, the types of fatigue that they struggle with the most, and which types of strength their athlete is most likely to see tested in competition. Understanding the basic principles I laid out and implementing the training guidelines is a great starting point. For more on this topic, look to future Classroom content.
Written by Kyle Ruth