Does Strength Training Too Young Limit Long-term Athletic Potential?

Dr. Anatoliy Bondarchuk is an Olympic Gold and Bronze medal winning hammer thrower and a highly accomplished coach in the former Soviet Union who now coaches in Canada. His book Transfer of Training was translated to English by Dr. Michael Yessis and his work has heavily influenced the sports performance world (certainly my views, which I’ve written about here, here and here).

When we think about the lore of training in the Soviet Union, Dr. Bondarchuk is one of those pioneers.

One of his perspectives is that youth athletes should not train maximum strength because heavy lifting decreases long-term athletic potential.

This is a big claim with heavy ramifications. Many strength and conditioning coaches do introduce max strength training to their youth athletes.

Could they be hampering their athletes’ long-term development by doing so?

The Argument

The first 6-8 weeks of strength training produce rapid strength gains due to neural adaptations.

Youth athletes naturally achieve strength gains through the maturation process. They get stronger just by going through puberty and growing.

Dr. Bondarchuk’s contention is that max strength training should be delayed until athletes have reached the end of their natural growth process in order to maximize long-term athletic potential. Once they have fulfilled their natural growth and strength gains, max strength training can be introduced such that then the rapid strength gains associated with beginning strength training are experienced.

It essentially allows the athlete to experience newbie gains when they aren’t newbies.

I think of it like hitting the NOS in a street race.

To maximize the NOS and hit the highest speed possible, you need to be patient and wait until your car is near its natural top speed. THEN you hit the boost. If you hit it too soon, while the car is still rapidly accelerating, it’s wasted.

For athletes, the concept follows that if max strength is introduced early, sure, they will experience the rapid strength gains that come with it, but down the road when they’ve hit their natural top speed they won’t have any NOS left to propel them to the next level

“Intensity kills sensitivity. Dr. Bondarchuk (who in my opinion is one of, if not the top expert on adaptation and training transfer) has stated that whether you use high intensity or low intensity with younger athletes, the results will be the same. The difference is that with high intensity work there is no coming back from high intensity, and the plasticity of the nervous system stiffens so that the only way you can keep improving is by using high intensity and or more volume of high intensity.” –Jeff Moyer, in this article on the Just Fly Sports website

I offer an analysis of the claim that training at high intensities (i.e. max strength training) decreases long-term nervous system adaptability and stifles long-term potential. Specifically, this article examines the adaptations to max strength training, how they relate to neuroplasticity, and my interpretation of how they interact with long-term athletic potential when introduced at a young age.

Let’s get this out of the way

Strength is good. Low-velocity, max strength is good. High-velocity strength is good. Force production = good. I don’t argue otherwise.

Let’s get this out of the way, too

This article specifically examines the role of maximum strength training in long-term athletic potential. Understand this discussion revolves around loads above 85% intensity.

What is athleticism?

I will do this subject injustice to keep this section short. High velocity contraction speed—“explosiveness,” as most athletes call it—is my short definition of athleticism.

If you can run, jump, cut, and “explode” quickly, you are athletic. Things that make you slower and less explosive make you less athletic. Through this lens, power production is the #1 factor in athletic performance.

This is the basic lens through which “athleticism” is viewed in this article.

Data

I understand the neurologic rationale behind the argument. But the big question…

Is there data?

To my knowledge there is no direct data in support of the claim that intense training decreases neuroplasticity or that high intensity training decreases adaptability to lower intensity stimuli.

A 2016 meta-analysis found no significant difference in training frequency (1, 2 or 3x per week) on muscular strength and jump, sprint, agility, and sport-specific performance in youth athletes.1 That a child can train once per week vs. three times per week and achieve similar results does seem to support the general theme of less is more.

However, just because changes don’t reach statistical significance doesn’t mean they aren’t practically significant. It could be that the kids training 2-3x per week did experience what us coaches and the kids themselves would consider significant improvements over their 1x per week counterparts. I didn’t read all 43 studies included in the meta, and unfortunately the meta didn’t included magnitude-based inference statistical analysis, only p-values.

Nonetheless, I don’t believe the meta-analysis sheds light on neuroplasticity or long-term development.

It would be interesting to investigate youth power and Olympic lifters and their long-term progress. This would certainly provide indirect data on early strength / power training specialization and long-term adaptability / potential.

However, if the end-goal is improved performance on the field, court, or track—not the platform—then the relevance of such findings come into question. After all, it is not always the strongest or most powerful athlete who wins.

In any case, lack of data doesn’t necessarily hurt the claim…but it doesn’t help it, either.

Finally, we move on to examining the adaptations of max strength training and how they relate to neuroplasticity and long-term athletic potential.

Nervous System Adaptations to Heavy Lifting

Prime mover activation

Increased prime mover activity is accomplished by increased rate coding and full motor unit recruitment. It seems as though increasing rate coding (which is also a primary adaptation to high velocity movements) and developing the skill of recruiting all motor units as a young athlete would not have a negative impact on long-term athletic adaptability. I don’t see any reason why delaying this adaptation would be advantageous or why it would decrease plasticity. In fact, I argue the opposite: these traits improve performance both in sport and training (at any intensity), thus facilitating long-term growth.

Muscle coordination

As weight increases, so does the activation of agonist, synergist, and usually antagonist musculature, presumably to stabilize the moving joints.

Antagonist activation is disadvantageous to high velocity force production. In this way, muscle coordination adaptations to heavy lifting may decrease high-velocity force production. Thus, this adaptation might contribute to making an athlete slower.

Matt Rhea has performed interesting field research regarding EMG patterns in agonist / antagonist pairs during sprinting (see this, for one example). He believes improved muscle coordination accounts for up to 61% of speed improvements in his athlete population (which is University of Alabama football, by the way). His athletes do a ton of unilateral work and sprint-like exercises in the weight room

Thus, muscle coordination adaptations to heavy bilateral training are likely disadvantageous for high velocity contraction ability, but appear to be highly plastic in collegiate aged athletes. I think it’s safe to assume University of Alabama football players lifted heavy as youth athletes, so this anecdotal evidence does not support a decrease in plasticity.

Structural Adaptations to Heavy Lifting and Long-term Performance

Hypertrophy

Hypertrophy comes with caveats. On the one hand, hypertrophy contributes to maximum force production, which aids athletic performance (to a point). Strength (low-velocity force output) is an athlete’s base by which power and high-velocity force production are built. A certain level of strength is necessary to achieve full athletic potential (where that threshold lies is an argument and likely several Ph.D. theses in itself). In terms of contributing to maximum force output, hypertrophy is beneficial.

On the other hand, hypertrophy also decreases maximum contractile velocity, creating slower muscle fibers. Slower athlete = worse athlete. Further, hypertrophy is added weight. It’s harder to be fast at 230lbs than it is at 180lbs.

Nonetheless, there exists a balance between max force contributions and high contractile velocity reductions to the end goal of systemic force production and velocity. Common sense tells us that bodybuilders and powerlifters are not fast or great athletes, but at the same time Olympic sprinters are decently jacked.

Take what you will.

Lateral force transmission

Increased lateral force transmission is very similar to hypertrophy in this regard. This adaptation increases total force production without any accompanying change to muscle properties, which seems at first to be advantageous, but it appears as though the mechanism by which increased lateral force transmission is increased—added costameres to the muscle fibers—also reduces high velocity contractile rate.

Thus, a balance exists here just as with hypertrophy.

Tendon stiffness

Increased stiffness benefits force transference from the lower leg to the ground, thus increasing sprint and jump performance. I do not see any reason why the development of stiffer tendons at a young age would hamper long-term athletic potential.

Fiber type shift

Strength training shifts the very high velocity type IIx fibers to a relatively slower type IIa fibers. Type IIa fibers are explosive (fast contracting), but less explosive than IIx fibers. Type IIx fibers contract approximately twice as fast as IIa fibers and 5-10x as fast as type I fibers.2 Delaying, limiting, or avoiding altogether this fiber type transition thus seems highly beneficial for athletic performance.

Colin Jackson—current 60m hurdles world record holder and former 110m hurdles world record holder—is reported to have 24% type IIx fibers and 34% type IIa fibers in his vastus lateralis.3

For context—9.3% IIx and 42.4% IIa fibers were found in the vastus lateralis of sedentary male adults.4 That’s quite different from the world champ.

High levels of IIx fibers likely equate to better performance in explosive movements. As strength training promotes a shift away from IIx fibers, I can see how delaying strength training may be advantageous for long-term potential.

This is a structural rather than a neural change, however.

Decreased neuroplasticity? I’m not sold. Decreased athletic potential? I’m listening…

Analyzing each of the above variables leads me to believe max strength training does not decrease neuroplasticity.

There is a factor not yet discussed, however: novelty.

Novelty facilitates neuroplastic change. Delaying strength training means delaying a novel stimulus.

Does this mean strength training decreases neuroplasticity? I think of it more so as removing a novelty option.

It’s like hearing a good joke. When is it the funniest? The first time you hear it. You become desensitized to the same joke the more you hear it. But that doesn’t mean other jokes become less funny.

Expanding on this point—that “intensity kills sensitivity”—I do not see a mechanism that would facilitate this. Adult athletes can improve 1RM strength with sub-maximal work, like speed sets or max power training, so why would that not be true for youth athletes after they are exposed to high intensity training?

Instead, I believe max strength training and the accompanying structural changes in muscle tissue cause performance decrements that may only be alleviated by more strength training, giving the perception that once high intensity training is introduced “there is no coming back.”

Indeed, once a fiber transitions from Type IIx to IIa, there is no coming back, unless you go to outer space5 or stop training altogether for a couple of months3.

Maximizing a youth athlete’s long-term athletic potential—which, to me, means maximizing power production—requires mitigating losses of IIx fibers.

Power can increase with max strength training, but at the cost of IIx fibers and decreased muscle contraction velocity through other mechanisms (hypertrophy, increased costameres, and potentially increased antagonist activation, as discussed above). Youth athletes naturally increase strength through the teenage years as part of the maturation process. Allowing them to achieve full or near-full natural strength gains before introducing max strength training spares IIx fibers and limits hypertrophy, costamere, and antagonist muscle activation increases, effectively preserving an athlete’s explosive potential ceiling while increasing strength.

Back to the NOS analogy: you have to wait for the right time to hit it in order to reach the highest speeds possible. Hit the NOS too soon and you do get a boost, but it ends before the car reaches its maximum performance potential.

For these reasons, it makes sense to me that introducing maximum strength training too early does decrease an athlete’s long-term explosive potential ceiling. You may get an immediate boost, but as Jeff Moyer says in his article linked in the intro, “what is the cost of doing business?”

Hence, I arrive at the same conclusion as many others, but maybe for other reasons. Or maybe they share my position and I don’t know it. Admittedly, I have not read every word ever written by each individual mentioned in this article.

This does not mean athletes can’t or shouldn’t lift. Submaximal lifting brings many benefits. It can be used to increase power and contraction velocity while mitigating the disadvantageous adaptations discussed here. It teaches proper technique, preparing the athlete for max intensity lifting. It builds mental skills and the habit of training. I’m all for lifting—just not for max intensity lifting with youngsters.

What of resisted and overspeed sprints?

Methods like overspeed and resisted sprints have been called into question. Overspeed work is a high velocity stimulus that, based on my understanding described in this article, will not result in disadvantageous adaptations to long-term potential. It is akin to performing band assisted jumps.

Likewise, resisted sprints—as long as speed decrements are below 50%, for a conservative guess—are akin to performing submaximal lifting. I do not believe this stimulus negatively impacts long-term potential from a neurophysiologic perspective.

With that said, my belief is that proficient sprint mechanics are a higher KPI for youth athletes than advancing neurophysiologic capability. Just as we want athletes to be technically proficient in the lifts before adding weight to the bar, I want kids to know how to run before introducing overspeed and resisted sprints. In practice, I have a general rule that I don’t do resisted or overspeed sprints with kids younger than 16 or 17.

Conclusion

Delaying strength training limits type IIx fibers transitioning to IIa fibers, hypertrophy, increased costamere counts, and increased antagonist muscle activation, thus mitigating losses in explosive potential. Accordingly, I believe max strength training with young athletes indeed does limit long-term performance for explosive-sport athletes, but not because of decreases in neuroplastic adaptability potential; rather, due to the structural adaptations associated with max strength training.


Shoutout to Jeff Moyer for having a friendly conversation with me about this article. It’s nice to be able to disagree with someone, talk about it, and become friends over it. Check out his website here, he does great work with youth athletes. 


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References

  1. Lesinski, M., Prieske, O., & Granacher, U. (2016). Effects and dose–response relationships of resistance training on physical performance in youth athletes: a systematic review and meta-analysis. British journal of sports medicine50(13), 781-795.
  2. Andersen, L. L., Andersen, J. L., Magnusson, S. P., Suetta, C., Madsen, J. L., Christensen, L. R., & Aagaard, P. (2005). Changes in the human muscle force-velocity relationship in response to resistance training and subsequent detraining.Journal of Applied Physiology99(1), 87-94.
  3. Trappe, S., Luden, N., Minchev, K., Raue, U., Jemiolo, B., & Trappe, T. A. (2015). Skeletal muscle signature of a champion sprint runner.Journal of Applied Physiology118(12), 1460-1466.
  4. Andersen, J. L., & Aagaard, P. (2000). Myosin heavy chain IIX overshoot in human skeletal muscle.Muscle & Nerve: Official Journal of the American Association of Electrodiagnostic Medicine23(7), 1095-1104.
  5. Bagley, J. R., Murach, K. A., & Trappe, S. W. (2012). Microgravity-induced fiber type shift in human skeletal muscle.Gravitational and Space Research26(1).

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