Effects of Strength Training in Preadolescents and Adolescents

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Effects of Strength Training in Preadolescents
and Adolescents

• Presented by Alecia Pollard

2
Introduction

• Muscle strength development in preadolescents and
  adolescents has been debated topic for the last
  couple of decades among health professionals,
  parents, and coaches.
• How much training?
• How soon?

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Strength Training

• Definition also known as weight training or
  resistance training. Using resistance methods to
  increase ones ability to exert or resist force.
• Free weights, machines, the individuals own
  weight, or other devices (e.g. elastic bands,
  medicine balls) provide resistance.

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Early Studies Cast Doubt

• Strength gains would neither benefit performance
  nor reduce the risk of injury in the childrens
  sports.
• Resistive weight training is dangerous for
  children because it carries an unacceptable risk
  of injury.

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Cont.

• 1978, study by Vrijens, reported the results of
  an 8-week resistance training program done
  3x/week by boys.
• Preadolescents were incapable of increasing
  strength
• However, the adolescents increased strength in
  all muscle groups tested.
• A decade later, Docherty et al reported that
  12-year old boys did not benefit from 3 session
  per week in a 4-6 week strength program following
  their competitive season
• These studies involved low resistance with one
  1-2 sets of exercises per session, which may not
  have produced measurable results.

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• Meta-analysis of strength training in children
  indicate that many studies are flawed by poor
  methodology.
• Children continue to grow as they progress
  through adolescence and demonstrate natural
  increases in strength
• Any research to examine strength gains in a child
  must incorporate an adequate control group to
  account for natural growth.
• In addition, the design of the training program
  is very important.
• The studies previously cited, low-intensity
  training volume and short-duration study
  protocols probably led to inherently flawed
  result.

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Bone and Growth Development

• Changes and adaptations occur in bone and muscles
• External and internal factors can affect the
  structure composition of the bone
• Weight bearing physical activity plays an
  important role in bone development
• Bone mineral density reaches about 90 of its
  peak by the end of the second decade

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Cont.

• Studies stated the importance of regular exercise
  during this period helps to optimize bone
  development and prevent osteoporosis later in
  life

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Injury Occurrences

• The US Consumer Product Safety Commission,
  through its National Electronic Injury
  Surveillance System (NEISS), had estimated the
  number of injuries that are associated with
  strength training equipment. 1991-1996 20,940
  to 26,120 injuries occurred each year under the
  age of 21
• NEISS data did not specify the cause of injury or
  whether if was from recreational or competitive
  weight lifting injuries

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Injuries Cont.

• Muscle strains account for most of all injuries
• 40-70
• Lumbar back is the most commonly injured area
• Followed by the knees, chest, shoulders, and
  elbows
• Fractures were the most common serious injuries
• A limited number of case reports raised concern
  about epipyseal injuries in the wrist and
  apophyseal injuries in the spine from weight
  lifting in skeletally immature individuals.
• These injuries were stated to be known as
  uncommon and are believed to be largely
  preventable by avoiding improper lifting
  techniques, maximal lifts, and improperly
  supervised lift.

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Injury Prevention

• Proper technique and lifting mechanics at all
  times
• Preadolescents or adolescents should begin a
  strength training program with low-resistance
  exercises until proper technique is learned.
• Supervision!!!
• ACSM, AAP, AOSSM, and NSCA, now support
  childrens participation in appropriately
  designed and competently supervised strength
  training programs

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Study I

• 1999, this study compared the effects of a low
  repetition-heavy load resistance training program
  to a high repetition-moderate load resistance
  training program, and the control group did not
  exercise
• Results showed a significant increase in both of
  the exercise groups compared to the control group
• Differences between the 2 exercise groups showed
  that the high repetition loading had a greater
  result on the leg extensions machine for the
  muscular endurance test
• The high repetition loading group was the only
  group that had significant results on the chest
  press for the 1RM and the muscular endurance test

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Study II

• 1990, this study looked at the effects of a
  20-week high intensity progressive training on
  maximal voluntary strength, evoked contractile
  properties, muscle cross-sectional area, and
  motor unit activation in preadolescent boys
• The experimental group trained for 3x week for 20
  weeks doing circuit training under adult
  supervision
• Results confirmed that resistance training wih
  this age group showed that they are capable of
  making strength gains following appropriate
  resistance training programs
• Everything measured increased except for there
  was no significant effects of training on any of
  the cross-sectional areas and no significant
  differences in body composition

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Study III

• Performing a 1-RM with preadolescence is to some
  observers unsafe and may be inappropriate or
  potentially injurious to children
• Other concerns are that this method of testing
  may cause structural damage to the developing
  musculoskeletal system
• This study evaluated the safety of the 1-RM
  strength testing in children and they assesed its
  practical application as a testing tool in this
  age group (6-12 years old)
• Results from this study indicated no abnormal
  responses to or injury from 1-RM testing

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How much and How Soon?

• This depends on an individual basis of each
  child
• Most of the studies said that 3x week, with a day
  of rest inbetween
• Progressive resistance exercises require
  successful completion of around 8-15 repetitions
  in good form before increasing weight or
  resistance
• Research states that children as young as age 6
  can improve strength when following age-specific
  resistance training guidelines

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Conclusion

• Guidelines and preventative measures (proper form
  and supervision!) to avoid injury while strength
  training was the most common recommendation from
  all of the studies
• A properly designed and supervised youth training
  program is most important when beginning training
  as a preadolescent or adolescent
• Adult strength guidelines should not be imposed
  on a child who is anatomically, physiologically,
  or psychologically less mature

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Cont.

• Conclusive observations form all the studies
  suggest that preadolescent and adolescent years
  are important for bone and muscle development
• 1-RM testing in this age group is safe and
  effective ONLY if administered by a qualified
  health professional to avoid injury and improper
  lifting mechanics

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References

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