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1)
Strength training for prepubescent males: is it safe?
This study examined the safety of one type of strength training for prepubescent males. Eighteen males (average age, 8.3 +/- 1.2 years) participated in a 45 min/session, three session/week, 14 week supervised strength training program with an attendance rate of 91.5%. Concentric work was done almost exclusively. KinCom analysis showed significant strength gain in this group (P less than 0.05), while an age, sex, and activity matched control group did not gain strength. Safety was evaluated by injury surveillance, blood pressure and heart rate monitoring, scintigraphy, and creatine phosphokinase measurement. Effects on growth and development, flexibility, and motor performance were also investigated, as these are factors with an impact on sports injury occurrence. Results showed that in the short term, supervised concentric strength training results in a low injury rate and does not adversely affect bone, muscle, or epiphyses; nor does it adversely affect growth, development, flexibility, or motor performance. As the safety question is multifaceted, this should not lead to the conclusion that strength training for prepubescents is uniformly safe. Further research is needed.
Am J Sports Med. 1987 Sep-Oct;15(5):483-9. Rians CB, Weltman A, Cahill BR, Janney CA, Tippett SR, Katch FI. Center for Sports Medicine and Health Fitness, Saint Francis Medical Center, Peoria, Illinois.
2)
Strength training and the immature athlete: an overview.
The developing musculoskeletal structures of the immature athlete are uniquely susceptible to injury, particularly at the physes. These growth plates are present in arm and leg bones, and some may not close until the late teen years. Early literature suggested that weight training might be inappropriate for these athletes. However, recent evidence suggests that, properly done, strength/resistance training may not only be safe, it may also help reduce the risk of injury for the young athletes. Nurses are often called upon to advise coaches of formal and community athletic programs, and need to know the underlying physiology of developing bone and muscle as well as the current recommendations related to training.
Pediatr Nurs. 1993 Jul-Aug;19(4):325-32. Metcalf JA, Roberts SO.
3)
Resistance training, skeletal muscle and growth.
Resistance training in youth and its effectiveness, possible effect on growth and safety considerations, has received considerable public and scientific attention in recent years. Although few early studies questioned the usefulness of resistance training in children, numerous recent studies have demonstrated its effectiveness in both children and adolescents. Nevertheless, the optimal intensity and volume of training for youths of different ages requires further study. The increase in strength following resistance training in youths, especially in prepubertal children, is believed to be due mainly to neural adaptations and only minimally, if at all, to muscle hypertrophy. Few studies have examined the long-term effect of resistance training on growth. The few which have, found that, contrary to the common misconception that resistance training may retard growth. Scientific evidence indicates that resistance training results in increased serum IGF-I and that there is no detrimental effect on linear growth. Finally, numerous studies have demonstrated that with appropriate supervision and precautions, resistance training can be safe and effective for children and adolescents.
Pediatr Endocrinol Rev. 2003 Dec;1(2):120-7. Falk B, Eliakim A. The Ribstein Center for Sport Medicine Sciences and Research, Wingate Institute, Netanya, Israel. bfalk@post.tau.ac.il
4)
Weight training in youth-growth, maturation, and safety: an evidence-based review.
OBJECTIVE: To review the effects of resistance training programs on pre- and early-pubertal youth in the context of response, potential influence on growth and maturation, and occurrence of injury. DESIGN: Evidence-based review. METHODS: Twenty-two reports dealing with experimental resistance training protocols, excluding isometric programs, in pre- and early-pubertal youth, were reviewed in the context of subject characteristics, training protocol, responses, and occurrence of injury. RESULTS: Experimental programs most often used isotonic machines and free weights, 2- and 3-day protocols, and 8- and 12-week durations, with significant improvements in muscular strength during childhood and early adolescence. Strength gains were lost during detraining. Experimental resistance training programs did not influence growth in height and weight of pre- and early-adolescent youth, and changes in estimates of body composition were variable and quite small. Only 10 studies systematically monitored injuries, and only three injuries were reported. Estimated injury rates were 0.176, 0.053, and 0.055 per 100 participant-hours in the respective programs. CONCLUSION: Experimental training protocols with weights and resistance machines and with supervision and low instructor/participant ratios are relatively safe and do not negatively impact growth and maturation of pre- and early-pubertal youth.
Clin J Sport Med. 2006 Nov;16(6):478-87. Malina RM. Tarleton State University, Stephenville, TX, USA. rmalina@wcnet.net
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The effect of a complex training and detraining programme on selected strength and power variables in early pubertal boys.
Complex training, a combination of resistance training and plyometrics is growing in popularity, despite limited support for its efficacy. In pre- and early pubertal children, the study of complex training has been limited, and to our knowledge an examination of its effect on anaerobic performance characteristics of the upper and lower body has not been undertaken. Furthermore, the effect of detraining after complex training requires clarification. The physical characteristics (mean+/-s) of the 54 male participants in the present study were as follows: age 12.3 +/- 0.3 years, height 1.57 +/- 0.07 m, body mass 50.3 +/- 11.0 kg. Participants were randomly assigned to an experimental (n = 33) or control group (n = 21). The training, which was performed three times a week for 12 weeks, included a combination of dynamic constant external resistance and plyometrics. After training, participants completed 12 weeks of detraining. At baseline, after training and after detraining, peak and mean anaerobic power, dynamic strength and athletic performance were assessed. Twenty-six participants completed the training and none reported any training-related injury. Complex training was associated with small increases (< or =5.5%) in peak and mean power during training, followed by decreases of a similar magnitude (< or = -5.9%) during detraining (P < 0.05). No changes or minor, progressive increases (< or =1.5%) were evident in the control group (P > 0.05). In the experimental group, dynamic strength was increased by 24.3 - 71.4% (dependent on muscle group; P < 0.01), whereas growth-related changes in the control group varied from 0 to 4.4% (P > 0.05). For 40-m sprint running, basketball chest pass and vertical jump test performance, the experimental group saw a small improvement (< or =4.0%) after training followed by a decline (< or = -4.4%) towards baseline during detraining (P < 0.05), whereas the control group experienced no change (P > 0.05). In conclusion, in pre- and early pubertal boys, upper and lower body complex training is a time-effective and safe training modality that confers small improvements in anaerobic power and jumping, throwing and sprinting performance, and marked improvements in dynamic strength. However, after detraining, the benefits of complex training are lost at similar rates to other training modalities.
J Sports Sci. 2006 Sep;24(9):987-97. Ingle L, Sleap M, Tolfrey K. Department of Sport, Health and Exercise Sciences, University of Hull, Hull, UK.
Nota: questo invece il link della Mayoclinic che ha fornito lo spunto per l'articolo di Olympian's News:
Spero di aver fatto cosa gradita a tutti perchè aldilà delle polemiche inutili una cosa è certa: Bodybuilding ruKes from cradle to the grave.
Buona lettura. Francesco
Il testo endogeno puo avere solo effetti contrari...da quelli da te descritti...
...quindi nemmeno col doping si ha la certezza.Studi approfonditissimi in Unione Sovietica verificarono che i ragazzi che praticavano sport(di qualunque tipo)erano in media+alti dei sedentari grazie propio agli ormoni che il movimento produce. Ancora l'altezza dipende soprattutto dal Gh che quando è prodotto in quantità eccessiva porta anzi a fenomeni di gigantismo...300000anni fa i nostri antenati erano mediamente alti come noi se non di più...questi erano cacciatori-raccoglitori abilissimi forgiati da una selezione naturale tremenda chi arrivava a20non andava all'università...addiritura poteva essere un soggetto dominante del branco ed è provabile che possedesse una forza bruta tremendaxpotersi difendere e cacciare i vari animali ostili che incontrava...insomma penso propio che facesse un attività sportiva che non aveva nulla da invidiare a quella del migliore atleta di oggi...che ne pensi del discorso ormoni???Poi nacque l'agricoltura 10000anni fa e addio superuomini l'altezza si abbasso a150-155cm e nacquero tutte le malattie che affliggano la nostra era...Oraxfavore guai chi mi dice che i primitivi morivano a40anni max perchè le case di cui morivano erano tutt'altro che le malattie.......Bene chiudiamo questa discussione perchè è degenerata del tutto scusami Paolo questo non effettivamente il luogoxparlare di una problematica cosi ampia e radicata quale il qualunquismo usato della maggioranza dei medici di cui Eagle sicuramente credo non faccia parte
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