CrossFit has taken the fitness world by storm over the last 15 years. It has been popularized for its high-intensity workouts and competitive spirit. But while it may offer a challenge to adults looking for a general fitness boost, the truth is that CrossFit can be detrimental to young athletes and their long-term athletic development. This bold statement isn’t just based on opinion but is backed by research and an understanding of the fundamental principles of strength and conditioning that CrossFit routinely ignores.
In this blog, I’ll explore why CrossFit is not just bad but terrible for young athletes. We’ll look at how it disregards the core principles of athletic development. From its over-reliance on non-specific, medium-intensity work to its flawed approach to speed, power, and strength development, CrossFit fails to prepare young athletes for success in their respective sports.
1. CrossFit Is Too General and Ignores Sport-Specific Needs
One of the biggest issues with CrossFit for young athletes is that it’s too general. CrossFit emphasizes varied movements performed at a high intensity, but this randomness fails to consider the specific needs of athletes in different sports. It can be argued that strength training or strength and conditioning programs are general in nature, which is true, however, the skills and specific adaptations can be targeted through training plans. CrossFit focuses on doing a bit of everything and does not have an overall plan or target week to week and month to month. It’s often said, there is little regard for movement quality or relevance which also leads to it being too general.
In sports science, specificity is a key principle in designing training programs. It is called the SAID principle or Specific Adaptation to Imposed Demands. Depending on the stage of development (training age and biological age), the training should be specific to the stage. It should also be specific to the time of year based on the annual plan and the block or phase the athlete is in. For example, if an athlete is in the 12–15-year-old age range, the specificity for their sport comes from playing the sport. The specificity in the weight room is focused on the more general skills of strength and speed development which transfer well at that age to their sport. As they age, sport-specific skills are still practiced in practice, but the general training in the weight room may be more specific to individual needs like improving force generation (strength), improving explosiveness (rate of force development or power), or elasticity (bounciness developed through various plyometrics or moving light weights faster), etc.
Charlie Francis, a renowned sprint coach, emphasized the importance of training at the extremes, which he termed the High-Low System. For example, to develop speed, an elite sprinter needed to hit speeds at 95% or greater relative to their top speed to move the needle. Subsequently, in order to recover well, but still improve work capacity, an elite sprinter would do runs at 75% or below, relative to their max speed over a given distance. They may also do weights under 80% of 1RM focusing on light weight circuits to promote recovery. Charlie exclaimed that the work between 76-94% of an elite sprinters top speed was considered medium-intensity work and should be avoided. It was too slow to increase speed and too fast to recover from in adequate time, creating unnecessarily high levels of fatigue. CrossFit, with its emphasis on medium-intensity work over extended periods, provides little to no benefit to athletes who need short, high-intensity bursts of speed and power with adequate work capacity levels.
Scientific support: Studies have shown that training programs tailored to the specific physical demands of a sport result in better performance and fewer injuries compared to generalized programs like CrossFit. A 2018 study published in the Journal of Strength and Conditioning Research found that sport-specific training led to greater improvements in performance metrics such as sprinting, agility, and strength compared to non-specific, generalized programs.
2. CrossFit’s Strength Work Isn’t Actually Developing Strength
CrossFit claims to build strength, but it often fails to deliver true strength development, especially for young athletes. CrossFit’s strength training is frequently combined with high repetitions and medium loads. Although young athletes will see great increases in strength with moderate loads because it is a novel stimulus, the issue is the excessive rep scheme, lack of quality reps, and attempting to complete the sessions as fast as possible. This type of training does not align with proven methods of strength development, which typically involve lifting moderate to heavy weights (training age dependent) within low to moderate rep ranges and long enough rest periods to build maximal strength.
The constant barrage of reps in CrossFit leads to fatigue, which degrades movement quality and prevents athletes from truly developing the maximal force production that is required in most sports. High-quality strength training focuses on performing movements with moderate to heavy loads and low to moderate rep ranges to build strength while maintaining consistent form. In contrast, CrossFit’s high-rep, medium-weight approach often leads to accumulation of fatigue, which not only limits strength development but increases the risk of injury. A young athlete will likely see an increase in strength, but what you don’t see is the ceiling for adaptation being lower and the accumulation of fatigue layered on top of all the other training that comes with being a team sport athlete.
Scientific support: Research has shown that lifting with heavier loads and lower reps is more effective for building strength compared to lifting lighter loads for many repetitions. A 2016 study published in the European Journal of Applied Physiology concluded that low-rep, high-load training leads to greater gains in strength and muscle hypertrophy.
3. CrossFit’s Definition of Power Is Flawed
In CrossFit, the term “power” is often misused. CrossFit defines power as performing more work over a specific timeframe, but this definition completely misses the mark when it comes to athletic development. Real power, in a sports performance context, is the ability to produce maximal force in minimal time—think of a sprinter exploding off the blocks or a soccer player cutting around their check into open space. These movements happen in fractions of a second (milliseconds), not over the prolonged time periods CrossFit focuses on.
True power training is about short, explosive movements—lifting light to moderately-heavy weights fast, or performing sprints and plyometrics (jumps). CrossFit’s long, drawn-out circuits of moderate-intensity work do not develop the type of explosive power required in most sports. Couple that with the fatigue and the ability to generate consistent power outputs diminishes quickly and so does the quality of your training session. This misunderstanding of power development can severely limit a young athlete’s potential, while increasing the risk of injury.
Scientific support: A 2015 study in the Journal of Strength and Conditioning Research highlights that power development requires exercises performed at high velocities with heavy loads, such as Olympic lifts or plyometric exercises. CrossFit’s emphasis on endurance or explosive movements under high fatigue, not quality explosive movements, fails to achieve this goal.
4. Speed Work Needs Sprinting, Not High-Rep Lifting
Another major flaw in CrossFit for young athletes is its misunderstanding of speed development. Speed work for athletes, particularly those in land-based sports like soccer, basketball, or track, should involve actual sprinting. Sprinting requires maximum-effort acceleration and deceleration or time at, or close to max speed with adequate rest periods. The rest periods are more important as athletes age, and they have more horsepower that they need to recover from. These movements can’t be replicated by lifting weights AT ALL.
In the weight room, speed can still be trained, but not sprinting speed. There is nothing fast enough in the weight room to mimic the joint and angular velocities of sprinting nor the neural output. However, in strength training we look at something called the force-velocity curve (See image below). The basics of the curve are the higher the force required, the slower the movement and the higher the velocity, the lower the force that can be produced. In training, as coaches, we look at “surfing the curve.” The goal is to have a well-balanced training plan that touches on all aspects of the curve. This will change with seasonality and age, but an effective approach like velocity-based training (VBT) can be used to target specific areas of the curve. VBT uses a device to measure the speed of specific exercises to ensure they are within certain speed ranges to train specific adaptations in strength and speed. This is completely different from CrossFit’s approach, which combines lifting with fatigue-inducing repetition schemes that only degrade speed and power quality.
Scientific support: Research supports the use of VBT to improve speed and power performance. A study from 2014 in the Journal of Sports Science and Medicine showed that lifting lighter loads at high velocities improved athletes’ sprinting and jumping ability more than traditional resistance training. CrossFit’s method of high-rep, low-quality work simply doesn’t provide the same benefit.
5. Fatigue Accumulation in CrossFit Leads to Low-Quality Work
The accumulation of fatigue in CrossFit workouts is perhaps its greatest flaw when it comes to young athletes. In CrossFit, athletes are often encouraged to push through fatigue in long, grueling workouts that combine weightlifting, bodyweight exercises, and cardio. While pushing through fatigue is thought to build mental toughness (it doesn’t), it also compromises the quality of movement, which is crucial for developing strength, power, and speed, and again increases the risk of injury.
When fatigue sets in, athletes lose the ability to perform exercises with proper form, leading to decreased training quality. Some will say that it the improper form will also increase the risk of injury, but that is a controversial topic for another time. However, by continuing to pile on fatigue within our young athletes, this will show up on field. They will be one step behind in their decision-making ability, they will be physically one step behind, they spend a little longer on the ground, or start overstriding, their mechanics in-game can change, and this can be enough increase the risk of a chronic injury or a more catastrophic injury. In contrast, a well-designed athletic program emphasizes high-quality repetitions with adequate rest between sets and a balanced plan based on the sport, seasonality, and training age to ensure that the athletes are filling the natural gaps in their sport training and not just doing work for the sake of work.
Scientific support: Research from the American Journal of Sports Medicine has found that fatigue significantly increases the risk of injury in athletes, as they are more likely to be in poor positions or make poor decisions in game or practice leading to potential injury. CrossFit’s relentless pursuit of “more work” without regard for fatigue is a recipe for poor athletic development and injury.
6. Conditioning Work Should Be Specific, Not Just “Work for Work’s Sake”
CrossFit often glorifies doing as much work as possible, regardless of quality or relevance to an athlete’s sport. Conditioning for athletes, however, should be specific to the demands of their sport. For land-based running athletes, this means run-specific conditioning, not endless circuits of rowing, burpees, and box jumps. There is a time and place, though, for what is considered “off-feet” conditioning, but that is not what I’m talking about here.
Young athletes need conditioning that mirrors the energy systems and movement patterns of their sport. For example, a soccer player should focus on maximal speed along with extensive tempo running and small sided games of various restrictions. This balance will increase the maximal speed as well as improve the aerobic ability needed to perform well in game (more on this in a later article on Speed Reserve for athletes). In contrast, CrossFit’s conditioning circuits, which emphasize non-specific movements and prolonged endurance, have little carryover to actual sports performance on-field. They’re too general and leave athletes susceptible to a variety of injuries from not building tolerance to ground impacts and speeds of the game.
Scientific support: Studies have shown that sport-specific conditioning leads to better performance improvements than generalized conditioning. A 2019 study in the Journal of Applied Physiology found that athletes who used sport-specific conditioning protocols saw greater gains in speed and endurance than those who followed generalized conditioning programs.
Conclusion: The Case Against CrossFit for Young Athletes
CrossFit’s general, high-intensity, non-specific approach to training is fundamentally at odds with the principles of long-term athletic development. From its flawed understanding of strength and power to its focus on fatigue over quality, CrossFit is simply not designed to meet the needs of young athletes. Instead of pushing young athletes into a training method that emphasizes quantity over quality, we should prioritize programs that build strength, speed, and power through age-appropriate, targeted, progressive, and high-quality training.
CrossFit may be great for adults looking for general fitness, but it’s a terrible fit for young athletes who need more than just work for work’s sake. As coaches and parents, our job is to ensure that young athletes are set up for long-term success, not just short-term exhaustion. By understanding these key principles, we can steer young athletes away from programs like CrossFit and toward training that will truly help them succeed in their sport.
