What the Science Says: Effects of Youth Resistance Training

Picking up where we left off in Youth Resistance Training, this article will peel the next layer of the onion back. We’ve established that kids should lift weights, but now we’re going to expand on why they should. The average coach would say they have kids lift weights to get stronger, but you’re not the average coach. To get you on the next level, we’re going to arm you with the knowledge to really empower the youth and get through to their parents. So, why do you have kids lift weights? One word: safety.

The Strong Will Survive

All sports have an inherent risk of injury; the very nature of sport and competition makes it impossible to completely remove it . However, strength training has been shown to be an effective means of decreasing non-serious(1) and severe(2) injuries, including those requiring surgery(1). In fact, programs in place to specifically address risk factors associated with injuries have shown a reduction in overuse injuries(3) and ACL tears in youth athletes(4). And, when kids did get injured, they recovered faster if they participated in some form of strength training prior to the injury(5).

While many opposed to youth strength training will cite injuries caused specifically during training sessions, many of those injuries have been attributed to the individual being either: a) unsupervised, b) supervised by under-qualified individuals, and/or c) training with inappropriate loads(6). And, just like all sports have some risk attached, recent research has shown that over 75% of the injuries occurring in the weight room were accidental(7) and avoidable under correct supervision and proper training loads(6).

In addition to lack of supervision or proper instruction, physical inactivity (which is becoming a bigger and bigger issue) is another factor leading to in-game injuries(8). Many of us unknowingly prepped our bodies for the external forces seen during gameplay by jumping and landing during free play (aka recess), stressing our growing bodies with forces up to 7x our bodyweight(9). But, since lack of free play is rampant in today’s youth(10), their young musculoskeletal systems are not being prepared to handle the external stresses of being the hammer (11). Enrolling children in general fitness programs that include some form of resistance training may make up for the physical stressors they are missing in their daily lives(12).  

That being said, strength and conditioning should not be seen as additional training that fits to an already busy, potentially multi-sport training schedule. A multifaceted program that includes resistance training which addresses deficiencies in both fitness and skilled movements should instead be seen as a compulsory component of a child's athletic development(13).

In fact, if a child is seen as “less athletic” than their peers, it has been shown that enrolling them in a strength and conditioning program will help them “catch up” to their peers via the accelerated adaptations driven by resistance training(14).

Girl Power

As mentioned before, boys and girls are more similar than they are different prior to hitting puberty. But, with the differences in musculoskeletal development during puberty, there are some considerations that must be made when talking about the two sexes. While movement quality is important for both, proper neuromuscular adaptations that come from a well-controlled resistance training program is a major determinant for the predisposition that girls face to sports injury, specifically injuries due to an uncontrolled valgus knee(15).

Research shows that the earlier a young girl starts to participate in a well-rounded strength and conditioning program, the lower the likelihood of an ACL injury(16). In addition to the prevention of such a common injury, strength training has been shown to give a “neuromuscular spurt”, which can be thought of as an accelerated adaptation, to girls that isn’t seen through sports practice alone(17). The gains seen during this “spurt” typically drive girls performance to a higher degree than seen in boys because the baseline of neuromuscular performance is lower in girls(17).

In practical terms, this means early adoption of strength training might be the difference between your girls being D-III All-Stars and D-I All-Americans.

The Brain Game: Psychosocial Benefits

While the research surrounding these benefits is more limited than the physical benefits, it has been shown that resistance training can lead to improvements in psychological well-being(18) and mood(19). But...more doesn’t always equal better. It’s also been shown that excessive volume of training actually reverses the positive mental benefits, especially in kids who are already emotionally vulnerable(20). This further reinforces that coaches prescribing strength and conditioning programs to youth athletes need a solid understanding of the principles of growth and development in children.

Measures of Effectiveness

So we’ve established all of the benefits associated with strength training in youth athletes. But, how much benefit are we talking about? Sure, they’ll get stronger, but how strong? Unfortunately, we’ll never be able to answer this. We’d need to see how strong a kid gets just living life, and then go back in time and start them on a training program. Since that isn’t possible, we have to simply look for improvements in kids training compared to kids who aren’t. Doing this, it’s been shown that strength training using free weights, resistance bands, and/or machines is an effective means to increase strength in children as young as 5 or 6 years old(19, 21). The data show as much as a 90% increase in strength(22), with an average of 30-40% in 8-20 weeks of training(23).

Now, before you pull your kindergartener into the weight room, remember that chronological age is not a great marker for when to start athletes in a strength training program. Biological age and emotional maturity will dictate this, as well as the ability to maintain the proper posture and positions necessary to complete exercises safely (24). The level of effectiveness of improving motor skill performances (jumping, running, and throwing) has been shown to be greater in children (pre-puberty) than in adolescents (post-puberty) who are all participating in strength training(25). This highlights that the effectiveness stretches beyond just muscular hypertrophy, since children do not have the proper androgen profile to significantly change that. Because of this, the goals for all youth protocols should be an increase in strength, function, and control as opposed to making significant gains in lean mass. When training children and adolescents, the view should always be long-term and the training should reflect the mechanism at play aligning with the athlete’s developmental stage(26).

Variation Not Randomization

Because a lot of the gains made from strength training in youth come from neural adaptations, detraining will occur rapidly(27). So, children should be encouraged to participate in a year-round resistance training program in order to maintain training-induced improvements in strength and coordination. Data shows that increases in strength gains directly increase with the frequency of training sessions per week(25). However, in order to avoid both overtraining or a plateau in gains, youth strength training programs should follow a model of progressive and systematic overload with a variation in exercise selection, intensity, volume, and frequency(28). This will also lead to a decrease in overuse injuries and, potentially, boredom by the children. But, don’t go off the rails here. Varied simply means not hitting 365 days of bench press (@Luke) or sitting in a single plane of motion all training session. Squat, step, lunge, push, pull. Boom...variance!

Chomping at the Bit

Alright coach, are you starting to get the picture? Are the pieces of the puzzle that is youth training coming together? We’ve identified the “why”: injury prevention, athleticism, and healthy development. We’ve danced around the macro view of the “how”: progressive and systematic overload with variance in movement. All that’s left is the “what”: the sets and reps. We’ll get there, but at this point you have the necessary tools to start building your program. Get to the drawing board now and we'll fill in the gaps next time. 

Sources

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  3. Micheli, L. (2006). Preventing injuries in sports: What the team physician needs to know. FIMS Team physician manual, 555-572.
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  15. Ford, K. R., Myer, G. D., & Hewett, T. E. (2011). Longitudinally decreased knee abduction and increased hamstrings strength in females with self-reported resistance training. Medicine & Science in Sports & Exercise, 43(5), 77.
  16. Myer, G. D., Sugimoto, D., Thomas, S., & Hewett, T. E. (2013). The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis. The American journal of sports medicine, 41(1), 203-215.
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  25. Lloyd, R. S., & Oliver, J. L. (2012). The youth physical development model: A new approach to long-term athletic development. Strength & Conditioning Journal, 34(3), 61-72.
  26. Faigenbaum, A. D., Farrell, A. C., Fabiano, M., Radler, T. A., Naclerio, F., Ratamess, N. A., ... & Myer, G. D. (2013). Effects of detraining on fitness performance in 7-year-old children. The Journal of Strength & Conditioning Research, 27(2), 323-330.
  27. American College of Sports Medicine. (2002). Progression models in resistance training for healthy adults. Med Sci Spor Exerc, 34, 364-380.
  28. Haff, G. G., & Triplett, N. T. (Eds.). (2015). Essentials of Strength Training and Conditioning 4th Edition. Human kinetics.

 

Ben Skutnik

Ben Skutnik

Power Athlete Block One Coach at Power Athlete
Ben grew up a football player who found his way into a swimming pool. Swimming for four years, culminating in All-American status, at a Division III level, Ben grew to appreciate the effects that various training styles had on performance and decided to pursue the field of Exercise Physiology. After receiving his M.S. from Kansas State University in 2013, Ben moved on to Indiana University - Bloomington where he is currently a PhD candidate and adjunct faculty, molding the young minds in the field of Human Performance. While in Bloomington, he spent some time on deck coaching swimming at the club level, successfully coaching several swimmers to the National and Olympic Trials meets.

Currently, Ben's feet are on dry land as he has shifted his focus towards empowering athletes in the weight room. Drawing from experience as an endurance athlete, Ben enjoys the challenge of applying the principles of the Power Athlete Methodology to non-traditional Power Athletes.
Ben Skutnik

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