Farm youth commonly perform animal care tasks such as feeding and watering. The purpose of this study was to determine the effects of age, bucket size, loading symmetry, and amount of load on upper body moments during carrying tasks. Fifty-four male and female participants in four age groups (8-10 years, 12-14 years, 15-17 years, and adults, 20-26 years) participated in the study. Conditions included combinations of large or small bucket sizes, unilateral or bilateral loading, and load levels of 10% or 20% of body weight (BW). During bucket carrying, elbow flexion, shoulder flexion, shoulder abduction, shoulder external rotation, L5/S1 extension, L5/S1 lateral bending, and L5/S1 axial rotation moments were estimated using video data. The 8-10 year-old group did not display higher proportional joint moments as compared with adults. Decreasing the load from 20% BW to 10% BW significantly decreased maximum normalized elbow flexion, shoulder flexion, shoulder abduction, shoulder external rotation, L5/S1 lateral bending, and L5/S1 axial rotation moments. Carrying the load bilaterally instead of unilaterally also significantly reduced these six maximum normalized joint moments. In addition, modifying the carrying task by using smaller one-gallon buckets produced significant reductions in maximum L5/S1 lateral bending moments.
http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
Weight lifting in children and youth is often viewed as a potentially harmful activity that could result in damage to bones, connective tissue, and muscle. Reviews, such as the one appearing in this issue of the journal by Behm et al. (Appl. Physiol. Metab. Nutr. 33: this issue), show that the balance of evidence indicates that weight lifting in pediatric populations is safe. Importantly, weight lifting, when performed in a safe and age-appropriate manner, is very beneficial on a number of health fronts, including strength and balance, self-esteem, and reducing cardiovascular risks. This is an understudied area that is still lacking in key areas of research to establish efficacy, dose-response relationships, and other health benefits.
http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
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.
http://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
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Kan vel også legge til at det finnes studier som viser at feks fotball er mere skadligt for kroppen, en feks styrketrening.
Så hva er egentlig værst, at gutten trener styrke 2 timer, 2 ganger i uka, eller at han trener fotball 2 timer, 2 ganger i uka?
09-10-09, 07:37
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