Different Aspects of Age Defined

Coaches should consider the ski racers age when developing a training and competition program. The age of the skier should be evaluated from several different aspects beyond their chronological age to ensure a skiers training, competition and recovery programming is designed based on their developmental age.

Chronological Age

Chronological age equals the number of years and days elapsed since birth. Skiers of the same age can differ by several years in their level of biological maturation by as much as four or five years. 

Developmental Age

Developmental age describes the relationship between growth and maturation over time and refers to the degree of physical, mental, cognitive and emotional maturity. It is highly individualized and is not always related to a skiers' physical development. The integrated nature of growth and maturation is a complex interaction that regulates the child's growth, neuromuscular maturation, sexual maturation, and general physical development during the first two decades of life.  

Skeletal Age

Skeletal age is the maturity of the skeleton determined by the degree of ossification of the bone structure. It is a measure of age that takes into consideration how far given bones have progressed toward maturity, not in size but their shape and position to one another. 

Ski Specific Training Age

Training age refers to the years of experience a skier has in a ski training environment. Although a child can begin a ski program at any age, Alpine Canada encourages children to start skiing during the Gliding Start stage through a ski club or ski school program and skiing with parents as often as possible to gain mileage and increased exposure to skiing.  

Relative Age

Relative age refers to differences in age among skiers born in the same calendar year. The relative age effect (RAE) refers to the observation that there is a more significant number of high performers born earlier in the year, January to June, who are more likely to persevere in sport, by being able to dominate physically through adolescence into early adulthood. Less mature skiers are susceptible to dropping out of ski racing as they may not feel as successful, motivated, or fulfilled by the experience (Stracciolini et al., 2016). 

RAE has been proven to be present in alpine skiing including a significant RAE among the female participants of the first Youth Olympic Games in 2012 and both genders at the FIS Junior World Championships (Müller, Müller, et al., 2015). In an analysis conducted by Øyvind, Lorås, and Pedersen in 2016, they reviewed the birthdates among the fifty top-ranked alpine skiers in the FIS World Cup system over the past twenty years. Their results showed an RAE among the male skiers in the speed disciplines only with no significant RAEs in men specializing in technical disciplines, and no RAEs at all in the women regardless of discipline. 

The conclusions of both studies indicated that late maturing ski racers could counteract the relative age disadvantage later in their career if they continue to focus on developing their physical fitness and skiing skills. Developing ski racers should be encouraged and supported by their parents and coaches to participate in the sport of ski racing past early adulthood when the RAE has been determined to have less effect (Øyvind, Lorås,  and Pedersen (2016) and Müller, Müller, et al. (2015).

Measuring & Monitoring Growth 

The Role of Monitoring Growth in Long-Term Athlete Development Istvan Balyi & Richard Way 

Peak Height Velocity

Peak height velocity (PHV) is the maximum rate of growth in stature during the adolescent growth spurt. Knowing when a skier is beginning their growth spurt and their peak height velocity, coaches can adjust training and competition programs to meet the needs of the developing skier. Monitoring growth before, during and after the adolescent growth spurt is very important for coaches to be able to create an individualized plan to optimize skiers’ development.

The following is a summary to guide coaches as they monitor their skiers and develop training, competition and recovery programs for their long-term development.

• Growth measurements are needed to monitor growth
• The onset of PHV, PHV and the start of menarche should be determined to be able to adjust training, competition and recovery programs according to the tempo of growth.
• Plotting growth will help to identify the onset of the growth spurt, and the peak of the growth (after growth decelerates).
• Before the onset of the growth spurt, standing height should be measured on every birthday, or at the beginning of the annual training cycle in clubs.
• Standing height, sitting height and arm span should be measured quarterly after the onset of the growth spurt.
• Training skill, speed and suppleness are based on chronological age, while stamina and strength are based the adolescent growth spurt. 

Ethical and Sensitivity Issues 

When conducting the measurement of growth, it is essential to realize the ethical and sensitivity issues surrounding the analysis of a child’s development.

Coaches must understand not only the physical changes to a child’s shape and size but also the implications they can have on personality and the skier's perception of their own body, as well as other people’s perception of their body. Coaches are in a unique place, in that they can offer sound advice and educate their skiers sensitively and appropriately.

How to Measure PHV 

Tools and equipment for measuring:

When considering the equipment needed for measurement, one must look at how much emphasis is going to be put on the measurement of stature. If stature data is going to be heavily incorporated into training plans, data must be very accurate, and thus, the more expensive the purchased equipment should be.

Ideal equipment:

• A free-standing or wall mounted stadiometer with a sliding headboard and a dial or digital readout. 

Acceptable equipment includes:

• An anthropometer or retractable steel measuring tape
• A headboard
• A smooth board with a straight end placed on the wall at 90 degrees
• A set square in place of a smooth board

Unacceptable equipment includes:

• A cloth measuring tape made of flexible material
• A carpeted floor
• An uneven floor
• No backboard 

Why is Measurement Accuracy so Important?

As previously mentioned, proper technique when measuring an athlete is essential, as random and measurement errors are common. It is the responsibility of the person measuring to ensure errors are minimized, as the more errors there are, the harder the results will be to interpret. Similarly, the more errors there is the less value the results will have. 

To decrease error, ensure:

• The environment is consistent and controlled
• Clothing is consistent and not bulky
• Feet are bare
• You have the cooperation of the athletes
• You follow standardized and consistent procedures 

What to Measure?

• Determining the rate of growth is dependent on accurate measurements; therefore, measurements need to be made to the nearest 0.1 cm.
• Each athlete should be measured and recorded twice, but these measurements should not differ by more than 0.4 cm. If they do not vary by more than 0.4 cm, the mean of the two measurements should be taken.
• If they do differ by more than 0.4 cm, a third measurement should be taken, and the median of all three measurements should be calculated.

Protocol for Sitting Height Measurement 

• The skier sits on the base of the stadiometer with knees slightly bent. Hands rested on knees.
• The buttocks and shoulders rest lightly against the stadiometer, which is positioned vertically behind the skier. Ensure there is no gap between the buttocks of skier and stadiometer.
• The tester applies gentle upwards traction to the skull behind the ears to ensure the trunk is fully stretched.
• Draw down the measuring bar, board or set square to the skiers head and record sitting height to the nearest 0.1 cm.
• Once the sitting height is calculated, it can be subtracted from the stature score, in order to derive the leg length height. 

Protocol for Standing Height Measurement 

• The skier stands erect in bare feet with heels, buttocks and shoulders pressed against the stadiometer.
• The heels are together with arms hanging freely by the side (palms facing thighs).
• The tester applies gentle upward traction to the skull behind the ears.
• The skier looks straight ahead, takes a deep breath and stands as tall as possible.
• Draw down the measuring bar, board or set square to the skiers' head and record standing height to the nearest 0.1 cm. 

Protocol for Arm Length Measurement 

• Mount a tape measure on the wall about shoulder height of the skiers being tested. Ensure the starting point of the tape measure is fixed to a corner of a wall. This is where the skiers' fingers must be fixed.
• The skier stands erect with their stomach and toes facing the wall, feet together and head turned to the right.
• The arms are extended laterally at shoulder level (horizontal) with palms facing forwards. Fingers stretched.
• The tip of the middle finger is aligned with the beginning of the tape measure (corner of the wall) and arms are out-stretched along with the tape measure.
• Use a ruler held vertically to the tape measure to record total arm span to the nearest 0.1 cm. 

Monitoring Tools 

Growth and development are natural, individual processes resulting in skiers developing at different rates. Tracking a skier's growth and development in cooperation with their parents allows coaches to evaluate and adjust a skier's training and competition program to match the needs of the developing skier to promote proper and safe athletic development.

Exposing young skiers who are experiencing periods of rapid growth to extreme training loads can result in injury to the skier. Often, the damage occurs unintentionally and results from the failure to recognize a skiers' growth rate, lack of modifications to training loads during rapid growth, and not monitoring their fatigue levels during the growth and maturation process. 

During PHV, skiers are at an increased risk of sustaining an overuse growth-related injury. As a result, the implementation of training interventions can be challenging. During adolescence, injury risk is elevated with high training loads due to rapid annual growth changes between 12-16 years. 

The adolescent growth period aligns with changes in joint stiffness, bone density and imbalances between strength and flexibility. During PHV, boys can grow between 7 cm and 12 cm per year, resulting in adolescent awkwardness in their movement mechanics. This rapid change between the skeletal structure and the development of strength to support the performance of athletic sport skills will vary between individuals resulting in a variation in readiness to perform and increased risk of injury (Towlson, C. et al. 2021).

Coaches should be aware of the increased risk of injury owing to training loads during adolescence if not managed appropriately. Using tools to estimate the age of peak height velocity (PHV) or percentage of final estimated adult stature attainment (%EASA) at specific periodized intervals can inform coaches about a young skiers' maturation status enabling them to modify training sessions appropriately to reduce the risk of injury to maintain long-term performance gains. The Excel templates below enable coaches to monitor a skier's progression through PHV and adjust their training programs accordingly.

Maturation Calculator - Girls (en anglais)

Maturation Calculator - Boys (en anglais)

References

Towlson, C., Salter, J., Ade J.D., et al. Maturity associated considerations for training load, injury risk and physical performance within youth soccer: one size does not fit all. Journal of Sport and Health Science 2021; 10:403-12. https://doi.org/10.1016/j.jshs.2020.09.003