By Emilie Maclaine Pont | 17 april 2025
On Friday, 4 April, another Masters of Movement Masterclass, organised by the Athletic Skills Model (ASM), took place. This edition focused on a question that resonates with many coaches, physiotherapists, and physical education teachers: how do we train young people responsibly, effectively, and enjoyably?— a question gaining increasing attention in the United States. With American keynote speakers Dr Joe Eisenmann and Nicole Rodriguez, the audience in Amsterdam was immersed to an evening filled with the latest insights at the intersection of science and practice.
The event began on a playful note. Jurgen van Teeffelen and Gerrit Heijkoop from the Slimmer Presteren Podcast kicked off the night with an ‘ASM-proof’ quiz. This light-hearted warm-up not only led to plenty of laughter but also set a vibrant tone for an evening of active learning.
Following the quiz, ASM founder René Wormhoudt discussed recent developments in strength and conditioning training. Once the domain of elite athletes, this form of training is now embedded in nearly every sport—from football to tennis—and across all ages from youth to seniors. This approach has become more holistic and data-driven. Wormhoudt emphasised the importance of developing motor skills from an early age. He noted that cultural differences, for instance, how boys and girls learn to move, can affect injury susceptibility later in life. Those who learn to execute a wide range of complex movements early on are generally better protected against injuries in the future.
"Occasionally Train Based on Biological Age"
The first keynote was delivered by Professor Dr Joe Eisenmann – a movement scientist at Saint Xavier University in Chicago, with over 25 years of experience in youth training and sports science. During his talk, he focused on training during growth spurts and a pivotal central question: What should I do when my child or pupil is going through the growth spurt?
"Chronological age says little about physical maturity"
Eisenmann distinguishes three core concepts: growth (increase in height, weight, and organ development), maturation (biological development), and development (social, emotional, motor). These processes do not occur simultaneously, on contrary, the occur at different rates and vary greatly among individuals. Therefore, chronological age alone is an unreliable indicator of physical maturity.
Eisenmann also introduced the concept of multiple age dimensions: chronological (how old someone is in years), relative (for example, whether someone has an early birthday in the year), biological (skeletal development, growth in height, and sexual maturation), behaviour, and training experience. All these factors influence selection process and training programmes. For example, the birth month effect highlights how children born earlier in the year (i.e. in the first quarter) are disproportionately selected for teams revealing how uneven the playing field can be.
To assess biological maturity, Eisenmann described several methods. For instance, the maturity offset method is a model that predicts growth spurts based on birth date, height, and weight. The Khamis-Roche method predicts adult height based on parental and individual height and weight. Finally, visual observation—the coach’s eye—, such as a sudden increase in leg length or shoe size, can be also valuable indicator.
By employing bio-banding (grouping children based on biological rather than chronological age), competition and training can be fairer, safer and more effective, according to Eisenmann. He pointed out that children prefer playing with peers of similar physically ability, which can reduce injury risks. During growth spurts, bones, muscles, and tendons do not grow synchronously, significantly increasing the risk of injuries, especially when combined with sleep deprivation and overtraining.
His advice: monitor training load and responses, for example, via digital or the traditional pen and paper surveys. Ensure sufficient sleep, teach children good basic movements (such as squats), temporarily replace overly intense training during growth spurts with balance and coordination exercises, and design individualised programmes. Eisenmann shared evidence indicating that such adjustments can reduce injury risk by up to ninety percent.
Strength Training per Developmental Phase
The second keynote speaker, Nicole Rodriguez, is a strength and conditioning coach with global experience and recently ASM-certified. She has worked with the Dutch volleyball team, the Czech national basketball team, in ice hockey, rugby, and is currently working with the U.S. women’s football team. Her presentation built upon Eisenmann’s insights exploring how to apply this knowledge in practice across different ages and larger groups.
Rodriguez introduced a three-phase model for young athletes divided into three developmental phases with each corresponding to specific training strategies:
- Foundation Phase (approximately eight to ten years old): The focus is on guiding the learning process with playful, ground-based activities. Think of running forms like snake runs or circular movements that train asymmetry and improve coordination. Emphasis is placed on balance, enjoyment, and brain activation. Parents are encouraged to participate to gain insight into their child’s experiences.
- Development Phase (eleven to fourteen years old): More attention is given to mobility, self-care, and injury prevention. Children attend fitness sessions once a week and learn how to care for their own bodies. Common concerns such as Osgood-Schlatter (knee pain) are actively monitored and addressed. Mental health is also prioritised, as injuries at this stage can have strong emotional impact.
- Performance Phase (fifteen to eighteen years old): The intensity of strength training increases (gym sessions twice a week), with specific training on acceleration, jumping, and explosiveness. Monitoring external load and nutrition becomes vital. Common injury risks now include the hips, hamstrings, and the spine. In this phase, education becomes an increasingly important element—athletes need to understand why they’re training in a specific way. This empower them to make informed decisions independently. The training is still enjoyable but becomes more structured and serious. Nicole Rodriguez concluded by reminding us that a ‘strong body’ also requires a ‘strong mind’. Mental resilience is essential for performing under pressure and coping with setbacks.
Bridging the Gap Between Science and Practice
Following the presentations, the audience engaged in a lively Q&A session. Questions ranged from the practical implementation of bio-banding to how to maintain motivation among teenagers.
René Wormhoudt closed the evening by emphasising the importance of continuing to build bridges between scientific evidence and everyday practice. “We must invest in the quality of movement from a young age,” he said. “Not just to prevent injuries or improve performance, but also to develop healthy, resilient individuals who continue to enjoy movement throughout their lives.”
