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Strength Training for the Growing Athlete

In this audio presentation, John Kiely, discusses the controversial topic of strength training for the growing athlete and dispels many of the common myths prevalent in this area.

This particular episode follows on from the previous discussion centred on the training implications for growing bone, by taking a closer look at the issue of weight training in young populations.  Is it advisable, or is it not? Is it damaging, or is it not? Is it beneficial, or is it not?  The debate has swung to and fro for many years, and has too frequently been polarised into extreme anti-, or extreme pro-, weight training stances.

In this podcast discussion, we attempt to explore the key relevant issues from as balanced a perspective as possible, weighing up the available factual evidence, and filling in the knowledge gaps with (hopefully) some applied practical common-sense.

  • Uploaded: 01.07.2010
  • Duration: 00:33:47
  • Views: 3592
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Sample key references:

  • American College of Sports Medicine Position Stand: Physical activity and bone health. American College of Sports Medicine. Med Sci Sports Exerc. 2004 Nov;36(11):1985-96.
  • Strength training by children and adolescents. American Academy of Pediatrics Council on Sports Medicine and Fitness, Pediatrics. 2008 Apr;121(4):835-40.
  • McGill SM. Low Back Disorders: Evidence-based Prevention and Rehabilitation. Human Kinetics. 2002.
  • McGill SM. Ultimate Back Fitness and Performance. University of Waterloo Press. 2005.

Faigenbaum AD, Kraemer WJ, Blimkie CJ, Jeffreys I, Micheli LJ, Nitka M, Rowland TW. Youth resistance training: updated position statement paper from the national strength and conditioning association. J Strength Cond Res. 2009 Aug;23(5 Suppl):S60-79.

Abstract

Youth resistance training: Updated position statement paper from the National Strength and Conditioning Association. J Strength Cond Res 23(5): S60-S79, 2009-Current recommendations suggest that school-aged youth should participate daily in 60 minutes or more of moderate to vigorous physical activity that is developmentally appropriate and enjoyable and involves a variety of activities. Not only is regular physical activity essential for normal growth and development, but also a physically active lifestyle during the pediatric years may help to reduce the risk of developing some chronic diseases later in life. In addition to aerobic activities such as swimming and bicycling, research increasingly indicates that resistance training can offer unique benefits for children and adolescents when appropriately prescribed and supervised. The qualified acceptance of youth resistance training by medical, fitness, and sport organizations is becoming universal. Nowadays, comprehensive school-based programs are specifically designed to enhance health-related components of physical fitness, which include muscular strength. In addition, the health club and sport conditioning industry is getting more involved in the youth fitness market. In the U.S.A., the number of health club members between the ages of 6 and 17 years continues to increase and a growing number of private sport conditioning centers now cater to young athletes. Thus, as more children and adolescents resistance train in schools, health clubs, and sport training centers, it is imperative to determine safe, effective, and enjoyable practices by which resistance training can improve the health, fitness, and sports performance of younger populations.The National Strength and Conditioning Association (NSCA) recognizes and supports the premise that many of the benefits associated with adult resistance training programs are attainable by children and adolescents who follow age-specific resistance training guidelines. The NSCA published the first position statement paper on youth resistance training in 1985 and revised this statement in 1996. The purpose of the present report is to update and clarify the 1996 recommendations on 4 major areas of importance. These topics include (a) the potential risks and concerns associated with youth resistance training, (b) the potential health and fitness benefits of youth resistance training, (c) the types and amount of resistance training needed by healthy children and adolescents, and (d) program design considerations for optimizing long-term training adaptations. The NSCA based this position statement paper on a comprehensive analysis of the pertinent scientific evidence regarding the anatomical, physiological, and psychosocial effects of youth resistance training. An expert panel of exercise scientists, physicians, and health/physical education teachers with clinical, practical, and research expertise regarding issues related to pediatric exercise science, sports medicine, and resistance training contributed to this statement. The NSCA Research Committee reviewed this report before the formal endorsement by the NSCA.For the purpose of this article, the term children refers to boys and girls who have not yet developed secondary sex characteristics (approximately up to the age of 11 years in girls and 13 years in boys; Tanner stages 1 and 2 of sexual maturation). This period of development is referred to as preadolescence. The term adolescence refers to a period between childhood and adulthood and includes girls aged 12-18 years and boys aged 14-18 years (Tanner stages 3 and 4 of sexual maturation). The terms youth and young athletes are broadly defined in this report to include both children and adolescents.By definition, the term resistance training refers to a specialized method of conditioning, which involves the progressive use of a wide range of resistive loads and a variety of training modalities designed to enhance health, fitness, and sports performance. Although the term resistance training, strength training, and weight training are sometimes used synonymously, the term resistance training encompasses a broader range of training modalities and a wider variety of training goals. The term weightlifting refers to a competitive sport that involves the performance of the snatch and clean and jerk lifts. This article builds on previous recommendations from the NSCA and should serve as the prevailing statement regarding youth resistance training. 

Faigenbaum AD. Strength training for children and adolescents. Clin Sports Med. 2000 Oct;19(4):593-619.

Abstract

The potential benefits of youth strength training extend beyond an increase in muscular strength and may include favorable changes in selected health- and fitness-related measures. If appropriate training guidelines are followed, regular participation in a youth strength-training program has the potential to increase bone mineral density, improve motor performance skills, enhance sports performance, and better prepare our young athletes for the demands of practice and competition. Despite earlier concerns regarding the safety and efficacy of youth strength training, current public health objectives now aim to increase the number of boys and girls age 6 and older who regularly participate in physical activities that enhance and maintain muscular fitness. Parents, teachers, coaches, and healthcare providers should realize that youth strength training is a specialized method of conditioning that can offer enormous benefit but at the same time can result in serious injury if established guidelines are not followed. With qualified instruction, competent supervision, and an appropriate progression of the volume and intensity of training, children and adolescents cannot only learn advanced strength training exercises but can feel good about their performances, and have fun. Additional clinical trails involving children and adolescents are needed to further explore the acute and chronic effects of strength training on a variety of anatomical, physiological, and psychological parameters.

Guy JA, Micheli LJ. Strength training for children and adolescents. J Am Acad Orthop Surg. 2001 Jan-Feb;9(1):29-36.

Abstract

Strength, or resistance, training for young athletes has become one of the most popular and rapidly evolving modes of enhancing athletic performance. Early studies questioned both the safety and the effectiveness of strength training for young athletes, but current evidence indicates that both children and adolescents can increase muscular strength as a consequence of strength training. This increase in strength is largely related to the intensity and volume of loading and appears to be the result of increased neuromuscular activation and coordination, rather than muscle hypertrophy. Training-induced strength gains are largely reversible when the training is discontinued. There is no current evidence to support the misconceptions that children need androgens for strength gain or lose flexibility with training. Given proper supervision and appropriate program design, young athletes participating in resistance training can increase muscular strength and do not appear to be at any greater risk of injury than young athletes who have not undergone such training.

Brady TA, Cahill BR, Bodnar LM. Weight training-related injuries in the high school athlete. Am J Sports Med. 1982 Jan-Feb;10(1):1-5.

Abstract

Eighty young athletes with weight training-related injuries were seen from August 1976 to August 1980. In 37 of the 80 athletes, it was difficult to pinpoint the cause of injury since the history revealed, in addition to weight training, either a program of running excessive mileage or participation in repetitive lap running in the gymnasium. The injuries of the remaining 43 athletes had a direct causal relationship to the weight training program. Twenty-nine developed lumbosacral pain. Seven of the 29 were hospitalized, and four required surgical treatment. Anterior iliac spine avulsion occurred in six cases, and laceration of the knee meniscus occurred as an initial injury in four athletes who required surgery. Four athletes developed a cervical sprain. Universal Gym (Cedar Rapids, IA), Leaper (Strength/Fitness Systems, Independence MO) Orthotron (Lumex Inc., Bay Shore, NY), and free weights were used either singly or in combination by these young athletes in weight training.

Potvin JR, McGill SM, Norman RW. Trunk muscle and lumbar ligament contributions to dynamic lifts with varying degrees of trunk flexion. Spine. 1991 Sep;16(9):1099-107.

Abstract

This study was done to assess the interplay between muscular and ligamentous sources of extensor moment during dynamic lifting with various loads and flexion angles of the trunk segment for 15 subjects lifting a total of 150 loads. Ligament forces predicted from an anatomically detailed biomechanical model did not generally contribute more than 60 Nm for most of the lifts because the lumbar spine was only flexed to a moderate and constant degree for each load condition. In contrast, additional moment demands associated with increases in hand load were supported by muscle. Although the compression forces on the L4-5 intervertebral disc were fairly insensitive to the interplay between the recruitment of muscle and ligament, the shear force was significantly higher with a greater degree of lumbar flexion. The risk of injury may be influenced more by the degree of lumbar flexion than the choice of stoop or squat technique.

Descarreaux M, Lafond D, Jeffrey-Gauthier R, Centomo H, Cantin V. Changes in the flexion relaxation response induced by lumbar muscle fatigue. BMC Musculoskelet Disord. 2008 Jan 24;9:10.

Abstract

The flexion relaxation phenomenon (FRP) is an interesting model to study the modulation of lumbar stability. Previous investigations have explored the effect of load, angular velocity and posture on this particular response. However, the influence of muscular fatigue on FRP parameters has not been thoroughly examined. The objective of the study is to identify the effect of erector spinae (ES) muscle fatigue and spine loading on myoelectric silence onset and cessation in healthy individuals during a flexion-extension task. METHODS: Twenty healthy subjects participated in this study and performed blocks of 3 complete trunk flexions under 4 different experimental conditions: no fatigue/no load (1), no fatigue/load (2), fatigue/no load(3), and fatigue/load (4). Fatigue was induced according to the Sorenson protocol, and electromyographic (EMG) power spectral analysis confirmed that muscular fatigue was adequate in each subject. Trunk and pelvis angles and surface EMG of the ES L2 and L5 were recorded during a flexion-extension task. Trunk flexion angle corresponding to the onset and cessation of myoelectric silence was then compared across the different experimental conditions using 2 x 2 repeated-measures ANOVA. RESULTS: Onset of myoelectric silence during the flexion motion appeared earlier after the fatigue task. Additionally, the cessation of myoelectric silence was observed later during the extension after the fatigue task. Statistical analysis also yielded a main effect of load, indicating a persistence of ES myoelectric activity in flexion during the load condition. CONCLUSION: The results of this study suggest that the presence of fatigue of the ES muscles modifies the FRP. Superficial back muscle fatigue seems to induce a shift in load-sharing towards passive stabilizing structures. The loss of muscle contribution together with or without laxity in the viscoelastic tissues may have a substantial impact on post fatigue stability.

Shirazi-Adl, A.; Parnianpour, M. Effect of changes in lordosis on mechanics of the lumbar spine-lumbar curvature in lifting. J Spinal Disord. 1999 Oct;12(5):436-47.

Abstract

Summary: Using a realistic nonlinear three-dimensional finite element model, biomechanics of the entire lumbar spine L1-S1, risk of tissue injury, and required local lumbar muscle exertion in extended and flexed postures are investigated under moderate to relatively large compression loads as great as 2800 N as the lumbar lordosis is altered from the undeformed value of -46[degrees] by +15[degrees] in extension or by as much as 38[degrees] in flexion. To prevent the instability of the passive structure in compression, the changes in segmental rotations are prescribed and the required sagittal/lateral moments at each level calculated. The effect of load distribution is considered by applying the whole compression on the L1 vertebra alone or among all vertebral levels with 90% or 80% of the compression on the L1 and the remaining evenly shared by the rest.

The results are markedly affected by the postural changes and load distributions. The primary global displacement responses are stiffened in the presence of combined loads. The axial compression load substantially increases the intradiscal pressure, facet loads, and disc fiber strains. The large facet loads at the caudal L5-S1 level causes large differential sagittal rotations at vertebral posterior and anterior bony structures, resulting in large stresses in the pedicles and pars interarticularis. The contribution of the passive structures in carrying the load is influenced by the lumbar lordosis and compression load magnitude. Slight flattening of the lumbar spine under large compression reduces the maximum disc fiber strains and required equilibrating moments without adversely affecting the disc pressure and ligament forces. During lifting tasks, the passive spinal structures are protected by slight to moderate flattening in the lumbar curvature, whereas larger flexion angles impose significantly higher risk by increasing the disc pressure, disc anulus fiber strains, ligamentous forces, and facet forces. Changes in lordosis also markedly affect the stabilizing sagittal moments; the required moments diminish in small flexion angles, thus requiring smaller forces in local lumbar muscles. Thus, the lumbar posture during heavy lifting could be adjusted to minimize the required moments generated by lumbar muscle exertions and the risk of tissue injury

Caldwell JS, McNair PJ, Williams M. The effects of repetitive motion on lumbar flexion and erector spinae muscle activity in rowers. Clin Biomech (Bristol, Avon). 2003 Oct;18(8):704-11.

Abstract

Objective. The purpose of this study was to investigate changes in lumbar flexion together with the pattern and level of muscle activity of selected erector spinae during a rowing trial. Background. Low back pain is a common problem in rowers. The amount of lumbar flexion occurring during rowing might influence the possibility of injury. Methods. Sixteen young adult school rowers participated in the study. Changes in lumbar flexion and muscle activity were recorded across the drive phase, at three stages of an ergometer based rowing trial. Lumbar flexion was calculated by computerised motion analysis of surface markers attached to the spinous processes of L1 and S1. Surface electromyography techniques were used to examine the magnitude of activity from three erector spinae muscles. The median frequency of the electromyographic signal was examined to quantify fatigue in the erector spinae muscles during isometric maximal effort muscle activation prior to and after the rowing trial.

Results. Lumbar flexion increased significantly (P<0.05) during the rowing trial, as did the magnitude of electromyographic activity from sites over the lumbar multifidus, iliocostalis lumborum and longissimus thoracis muscles. The median frequency decreased significantly (P<0.05) in each muscle examined.

Conclusions. The findings showed that rowers attain relatively high levels of lumbar flexion during the rowing stroke, and these levels are increased during the course of the rowing trial. Indirect evidence of muscle fatigue in erector spinae muscles was also apparent, and this observation may in part be responsible for the increased levels of lumbar flexion observed. Excessive lumbar flexion may influence the potential for injury to spinal structures. An awareness of increased lumbar flexion and muscle fatigue in the erector spinae muscles may be important for injury prevention programs for rowers.

Baranto A, Hellström M, Cederlund CG, Nyman R, Swärd L. Back pain and MRI changes in the thoraco-lumbar spine of top athletes in four different sports: a 15-year follow-up study. Knee Surg Sports Traumatol Arthrosc. 2009 Sep;17(9):1125-34. Epub 2009 Mar 21.

Abstract

A total 71 male athletes (weight lifters, wrestlers, orienteers, and ice-hockey players) and 21 non-athletes were randomly selected, for a baseline MRI study. After 15 years all the participants at baseline were invited to take part in a follow-up examination, including a questionnaire on back pain and a follow-up MRI examination. Thirty-two athletes and all non-athletes had disc height reduction at one or several disc levels. Disc degeneration was found in more than 90% of the athletes and deterioration had occurred in 88% of the athletes, with the highest frequency in weight lifters and ice-hockey players. 78% of the athletes and 38% of the non-athletes reported previous or present history of back pain at baseline and 71 and 75%, respectively at follow-up. There was no statistically significant correlation between back pain and MRI changes. In conclusion, athletes in sports with severe or moderate demands on the back run a high risk of developing disc degeneration and other abnormalities of the spine on MRI and they report high frequency of back pain. The study confirmed our hypothesis, i.e. that most of the spinal abnormalities in athletes seem to occur during the growth spurt, since the majority of the abnormalities demonstrated at follow-up MRI after the sports career were present already at baseline. The abnormalities found at young age deteriorated to a varying degree during the 15-year follow-up, probably due to a combination of continued high load sporting activities and normal ageing. Preventive measures should be considered to avoid the development of these injuries in young athletes.

Kujala UM, Taimela S, Erkintalo M, Salminen JJ, Kaprio J. Low-back pain in adolescent athletes. Med Sci Sports Exerc. 1996 Feb;28(2):165-70.

Abstract

In this 3-yr longitudinal study we investigated the occurrence of low-back pain and anatomic changes in the low back in relation to loading and injuries among 98 adolescents: 33 nonathletes (16 boys, 17 girls), 34 boy athletes (17 ice hockey, 17 soccer players), and 31 girl athletes (17 figure skaters, 14 gymnasts). During the 3-yr follow-up, low-back pain lasting longer than 1 wk was reported by 29 (45%; 95% CI, 32%-57%) athletes and by 6 (18%; 95% CI, 7%-35%) nonathletes (P = 0.0099). Acute back injury was reported by 17 of 19 subjects who also reported low-back pain (89%; 95% CI, 67%-99%) and by 2 of 63 of those without prolonged low-back pain (3%; 95% CI, 0%-11%) (P < 0.0001). Among 43 girls participating in baseline and follow-up MRI examinations of the lumbar spine, new MRI abnormalities were found in 6 of 8 reporting acute back injury (75%; 95% CI, 35%-97%) and in 8 of the remaining 35 girls (23%; 95% CI 10% to 40%) (P = 0.018). In conclusion, excessive loading that involves a risk for acute low-back injuries during the growth spurt is harmful to the lower back.

Swärd L. The thoracolumbar spine in young elite athletes. Current concepts on the effects of physical training. Sports Med. 1992 May;13(5):357-64.

Abstract

Due to the increased interest in physical fitness and to the fact that athletes start their training at younger ages the risk for injuries to the growing individual has increased. The spine, as with the rest of the skeleton, is at greater risk of injury during growth, especially during the adolescent growth spurt. Back pain is more common among athletes participating in sports with high demands on the back than other athletes and nonathletes. Disc degeneration, defined as disc height reduction on conventional radiographs and reduced disc signal intensity on MRI, has been found in a higher frequency among wrestlers and gymnasts than nonathletes. Abnormalities of the vertebral bodies including abnormal configuration, Schmorl's nodes and apophyseal changes are common among athletes. These abnormalities are similar to those found in Scheuermann's disease. Athletes with these types of abnormalities have more back pain than those without. Spondylolysis has been found in higher frequencies than expected among athletes representing many different sports. Spondylolysis has been reported in up to 50% of athletes with back pain. Scoliosis has been found in up to 80% of athletes with an asymmetric load on the trunk and shoulders, such as javelin throwers and tennis players. The scoliosis, however, is a small curvature and does not cause back pain.

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The information provided in this audio presentation is used solely at the user's own risk. UK Athletics Limited and the individuals represented in this audio presentation have taken reasonable care to ensure that the information contained on it is accurate. However, no warranty or representation is given that the information and materials contained in this audio presentation are complete or free from errors or inaccuracies. To the extent permitted by applicable law, UK Athletics Limited accepts no liability for any loss or damages or expenses of any kind including without limitation compensatory, direct, indirect or consequential damages, income or profit, loss of or damage to property, or claims by third parties how so ever arising in connection with your use of the audio presentation or the material contained within it. This exclusion of liability shall not apply to damages arising from death or personal injury caused by the negligence of UK Athletics Limited or any of its employees or agents.

Comments (2)

  1. Posted by Anonymous on 02/07/2010 at 12:26 AM

    I teach olympic lifting to my young long jumpers and sprinters and with guidance from my physio and GB strength coach, I have found that the benefits are well worth the effort. I do agree that as the coach you must monitor the physical state of the athletes at all times. Don’t forget that children weight lift all day long, at play they climb and jump from height, scale trees and drop down to the groung pull themselves up from the ground and we all did this and lived on to tell the tale. I myself weight trained from an early age around 12yrs and have suffered no ill effects, and have had no major injuries. As a good standard rugby player sprinter I was so much more powerful than many older kids. However, proper posture and form must be high if not paramount in a weight session and the coaches knowledge must be of a high standard and constantly updated.  Given the proper environment and knowledge I have found weight training to be of great benefit to my young athletes.

  2. Posted by Joe Holden on 01/02/2014 at 05:51 PM

    Excellent audio presentation - easy to listen to and very informative.  Please can you let me know when the next one from John Kiely - ‘Technical and Exercise Selection Considerations’ - is up on uCoach

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