There is a tendency among new CrossFit athletes and trainers to avoid heavy days entirely or execute them incorrectly. However, CrossFit is a strength and conditioning program. While people sometimes characterize CrossFit by its programming of mixed-modal workouts for time (“met-cons”), this is a limited view. Days devoted to strength training are essential to CrossFit and are integral to CrossFit’s prescription of constantly varied workouts.
Heavy days are necessary to build top-end strength and power. Power output decreases with time, meaning an athlete’s work capacity in very short time domains sets the theoretical limit for his or her entire curve (Figure 1). It is possible to have high levels of short-duration power and little power elsewhere (e.g., a powerlifter), but it is impossible to have low levels of short-duration power and higher levels of longer-duration power. Therefore, heavy days are essential to a general physical preparedness program and should be used at least once a week or once every two cycles (where a cycle is three on, one off).
All of that said, it is important to understand that heavy days can be completed with most any weightlifting or gymnastics movement, such as weighted dips and pull-ups, or lifting odd objects (e.g., sandbags, axles). More often than not, however, a barbell is the best and simplest implement for this task; the barbell’s ease and range of loading is impossible to match with other equipment. Heavy days thus conceived may also include all variations of standard barbell movements (e.g., hang, power, lifting from a deficit, pulling from pins/bumpers).
Heavy days are not the only time athletes can drive strength adaptations. Even within a metabolic-conditioning workout, depending on the task and capacity of the athlete, any number of exercises may build strength. Push-ups for novices build pressing strength similar to a bench press, and attempting a 95-lb. thruster for a new CrossFit athlete builds squatting strength. As an athlete’s strength increases, however, push-ups and 95-lb. thrusters tend to favor other adaptations, such as stamina, and greater loads are necessary to further increase top-end power.
Implementation
A true “heavy day” workout consists of small sets, most often in the range of 1 to 5 repetitions, where the total volume of working repetitions is approximately 7 to 25. Repetitions significantly outside this range do not produce the desired response. If there are too few repetitions (e.g., 1 repetition at a near-maximum load), the athlete does not produce enough stress on the taxed muscles to drive a new adaptation. Conversely, too many repetitions (e.g., 30 or more at near-maximum load) produces too much stress for the athlete to recover from in a reasonable time period. The working sets generally occur at or above 80 to 85 percent of a 1-repetition-maximum load — a working set should be heavy enough to require concentrated effort. The working sets also should not produce a significant cardiorespiratory response.
Repetition schemes may vary. As a general guideline, the higher the repetitions in a set or across the entire session, the lower the loading. This approach tends to better develop muscular stamina and/or technique. The lower the repetitions, the higher the loading. This approach tends to better develop top-end strength. Both approaches should be used. Repetition patterns include standard schemes such as 7 x 1, 5 x 3, 5 x 5 (sets x reps); pyramid-like patterns of 1-2-3-2-1 (reps per set); descending/ascending schemes such as 5-4-3-2-1 (reps per set); no set specificity (e.g., work up to a max push press); and on-the-minute training (1, 2, or 3 repetitions on the minute, every minute for 10 minutes), among others.
The trainer should clearly describe how the working sets should be approached to avoid confusion. For example, the workout may be 5 x 5 front squats. Does the trainer want athletes to increase the load with every set? Does the trainer want athletes to hold a certain percentage across all sets? Or, does the trainer perhaps want athletes to find a new 5-repetition maximum, meaning the exact number of working sets is less important (maybe it takes 4 sets, maybe 5 sets)? All these approaches have validity and potential benefits, but the trainer should indicate the intent for that particular day.
During the working sets, the trainer must appropriately apply the principles of threshold training just as he or she would in any other workout — i.e., once an athlete’s mechanics significantly deviate from the points of performance, the load needs to be reduced. This is especially true when multiple verbal and visual cues do not result in any improvement in mechanics. It is sometimes possible for the trainer to fix the mechanics at lighter loads and then allow the athlete to again increase the load gradually. Deviations from points of performance may also require the trainer to change the movement for a few repetitions before using the entire movement (e.g., using snatch pulls to correct an athlete who is pulling early in the full snatch).
Group Management
A trainer has several logistical and safety concerns to manage when leading a strength session for a group. A heavy day best begins with a thorough warm-up to prepare athletes for maximal loading (e.g., increase core temperature and improve range of motion). Trainers should correct and refine mechanics across warm-up sets of the movement to minimize the risk of improper execution under heavier loads. Finding the best way to complete warm-up sets usually becomes an intuitive process as athletes become more experienced with lifting heavy. However, most athletes require direction through this process during their first few years of training. Whatever the warm-up is, trainers should not fatigue athletes for the work sets; instead, warm-up sets gradually prime the body for heavier loading while refining the mechanics of the lift.
The trainer must also teach each athlete how to bail and/or spot as necessary before any significant weight is attempted. It is easiest to have participants practice this with a PVC or dowel. A trainer cannot assume athletes will perform bailing or spotting techniques correctly without being taught. The gym floor also needs to be arranged to ensure safe walkable distance between racks and working athletes, and the floor should be free of extra equipment. Trainers may choose to have participants share racks, in part to reduce equipment and space needs, but also because sharing racks allows athletes to help one another with loading, unloading, and spotting. Sharing also aids in ensuring adequate rest time between sets so athletes fully recover.
Universality
Remember, heavy days are important for everyone: the young, old, fit, and unfit. Excluding anyone from this work will blunt important strength adaptations. Using the concept of relative intensity, a trainer can have any athlete lift a load that is relatively heavy for him or her. Start beginners of any age or physical capacity with very light weight and more repetitions (either within each set or by increasing the total number of sets) and very gradually progress to a reasonably challenging working weight. Most important to this process is insisting on near-perfect mechanics before loading increases. Do not be afraid to hold an athlete at a given load until mechanics are where you want them to be. Even with the most conservative approach, newer athletes will often set a personal record every time they lift heavy. As the lifter becomes more experienced, sessions without a new personal record may occur, but setting a personal record is not necessary to reap the benefits of lifting heavy.
CrossFit trainers should regularly program strength days with their clients and ensure all participants achieve the desired stimulus during the training session. These sessions provide coaches and athletes with opportunities to improve mechanics, acquire new skills, and see progress in a modality vital to developing work capacity across broad time and modal domains — i.e., fitness.
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Heavy Days
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