PURPOSE: To compare the effects of a 10-week training program with two different exercises -- traditional hamstring curl (HC) and Nordic hamstrings (NH), a partner exercise focusing the eccentric phase -- on muscle strength among male soccer players. METHODS: Subjects were 21 well-trained players who were randomized to NH training (n = 11) or HC training (n = 10). The programs were similar, with a gradual increase in the number of repetitions from two sets of six reps to three sets of eight to 12 reps over 4 weeks, and then increasing load during the final 6 weeks of training. Strength was measured as maximal torque on a Cybex dynamometer before and after the training period. RESULTS: In the NH group, there was an 11% increase in eccentric hamstring torque measured at 60 degrees s(-1), as well as a 7% increase in isometric hamstring strength at 90 degrees, 60 degrees and 30 degrees of knee flexion. Since there was no effect on concentric quadriceps strength, there was a significant increase in the hamstrings:quadriceps ratio from 0.89 +/- 0.12 to 0.98 +/- 0.17 (11%) in the NH group. No changes were observed in the HC group. CONCLUSION: NH training for 10 weeks more effectively develops maximal eccentric hamstring strength in well-trained soccer players than a comparable program based on traditional HC.
[Action of a daily physical education lesson on changes in the cerebral circulation of schoolchildren under the effect of a daily and weekly study load].
School of Physical Education, Faculty of Education, University of Victoria, Box 3015, STN CSC, Victoria, British Columbia, Canada V8W 2P1. pjnaylor@uvic.ca
Childhood physical inactivity and obesity are serious public health threats. Socioecological approaches to addressing these threats have been proposed. The school is a critical environment for promoting children's health and provides the opportunity to explore the impact of a socioecological approach.
Thirty percent of children in British Columbia, Canada, are overweight or obese, and 50% of youths are not physically active enough to yield health benefits.
Action Schools! BC, a socioecological model, was developed to create 1) an elementary school environment where students are provided with more opportunities to make healthy choices and 2) a supportive community and provincial environment to facilitate change at the school and individual levels.
The environment in British Columbia for school- and provincial-level action on health behaviors improved. Focus group and project tracking results indicated that the Action Schools! BC model enhanced the conceptual use of knowledge and was an influencing factor. Political will and public interest were also cited as influential factors.
The Action Schools! BC model required substantial and demanding changes in the approach of the researchers, policy makers, and support team toward health promotion. Despite challenges, Action Schools! BC provides a good example of how to enhance knowledge exchange and multilevel intersectoral action in chronic disease prevention.
Notes
Cites: CMAJ. 2000 Nov 28;163(11):1429-3311192647
Cites: Am J Prev Med. 2001 Aug;21(2):101-911457629
Cites: Int J Obes Relat Metab Disord. 2002 Mar;26(3):425-3611896500
Cites: Am Psychol. 1992 Jan;47(1):6-221539925
Cites: Soc Sci Med. 2003 Feb;56(3):449-6412570966
Cites: Health Educ Q. 1988 Winter;15(4):351-773068205
Cites: Am J Prev Med. 2002 Aug;23(2 Suppl):15-2512133734
Active Smarter Kids (ASK): Rationale and design of a cluster-randomized controlled trial investigating the effects of daily physical activity on children's academic performance and risk factors for non-communicable diseases.
Evidence is emerging from school-based studies that physical activity might favorably affect children's academic performance. However, there is a need for high-quality studies to support this. Therefore, the main objective of the Active Smarter Kids (ASK) study is to investigate the effect of daily physical activity on children's academic performance. Because of the complexity of the relation between physical activity and academic performance it is important to identify mediating and moderating variables such as cognitive function, fitness, adiposity, motor skills and quality of life (QoL). Further, there are global concerns regarding the high prevalence of lifestyle-related non-communicable diseases (NCDs). The best means to address this challenge could be through primary prevention. Physical activity is known to play a key role in preventing a host of NCDs. Therefore, we investigated as a secondary objective the effect of the intervention on risk factors related to NCDs. The purpose of this paper is to describe the design of the ASK study, the ASK intervention as well as the scope and details of the methods we adopted to evaluate the effect of the ASK intervention on 5 (th) grade children.
The ASK study is a cluster randomized controlled trial that includes 1145 fifth graders (aged 10 years) from 57 schools (28 intervention schools; 29 control schools) in Sogn and Fjordane County, Norway. This represents 95.3 % of total possible recruitment. Children in all 57 participating schools took part in a curriculum-prescribed physical activity intervention (90 min/week of physical education (PE) and 45 min/week physical activity, in total; 135 min/week). In addition, children from intervention schools also participated in the ASK intervention model (165 min/week), i.e. a total of 300 min/week of physical activity/PE. The ASK study was implemented over 7 months, from November 2014 to June 2015. We assessed academic performance in reading, numeracy and English using Norwegian National tests delivered by The Norwegian Directorate for Education and Training. We assessed physical activity objectively at baseline, midpoint and at the end of the intervention. All other variables were measured at baseline and post-intervention. In addition, we used qualitative methodologies to obtain an in-depth understanding of children's embodied experiences and pedagogical processes taking place during the intervention.
If successful, ASK could provide strong evidence of a relation between physical activity and academic performance that could potentially inform the process of learning in elementary schools. Schools might also be identified as effective settings for large scale public health initiatives for the prevention of NCDs.
Clinicaltrials.gov ID nr: NCT02132494 . Date of registration, 6(th) of May, 2014.
In this study, we examined the acute effects of submaximal resistance exercise on immunological and hormonal parameters in 7 resistance-trained and 10 non-resistance-trained males. The participants, who were aged 29.5 +/- 7.1 years (mean +/- s), performed submaximal resistance exercise at 75% of their one-repetition maximum. Blood samples were taken before, during, immediately after, and 30, 60 and 120 min after exercise and analysed for leukocyte subpopulations and stress hormones. Total leukocytes, neutrophils and monocytes increased during exercise, reaching their maximum 2 h after exercise. Lymphocytes increased during exercise, T-helper cells returned to resting values after exercise, and natural killer cells and T-suppressor cells decreased below resting values. The CD4/CD8 ratio decreased during exercise but increased during recovery. The resistance-trained participants tended to have lower T-helper cell counts before, during and immediately after exercise and a lower CD4/CD8 ratio during recovery than the non-resistance-trained participants. Plasma cortisol correlated positively with leukocytes during exercise (r = 0.572, P
Mass examination in organized populations at industrial enterprises made it possible to bring to light a statistically significant different effect of the level of productive labor and sport activity on the prevalence of frequent alcohol consumption as one of CHD risk factors. A sufficient degree of regular physical training made a considerable effect on a decrease in CHD prevalence.
To assess the impact of an active school model on children's physical activity (PA).
16-month cluster randomised controlled trial.
10 elementary schools in Greater Vancouver, BC.
515 children aged 9-11 years.
Action Schools! BC (AS! BC) is an active school model that provided schools with training and resources to increase children's PA. Schools implemented AS! BC with support from either external liaisons (liaison schools, LS; four schools) or internal champions (champion schools, CS; three schools). Outcomes were compared with usual practice (UP) schools (three schools).
PA was measured four times during the study using pedometers (step count, steps/day).
Boys in the LS group took 1175 more steps per day, on average, than boys in the UP group (95% CI: 97 to 2253). Boys in the CS group also tended to have a higher step count than boys in the UP group (+804 steps/day; 95% CI: -341 to 1949). There was no difference in girls' step counts across groups.
The positive effect of the AS! BC model on boys' PA is important in light of the current global trend of decreased PA.
Physiological and biochemical profiles of six elite Canadian 800 meter runners are presented. Anthropometric data was recorded. Aerobic capacity was assessed on a treadmill run to fatigue; the initial treadmill velocity was 2.22 m X s-1 increasing by 0.22 m X s-1 each minute. VO2max was determined by the mean of the four highest consecutive 15 second values. The Anaerobic Speed Test (AST) (20 degrees incline, 3.52 m X s-1 to fatigue) was used to assess anaerobic performance characteristics. Two minute post-AST blood samples were analyzed for lactate. Needle biopsies were obtained at rest from the vastus lateralis muscle. The muscle fibers were classified and a homogenate of the muscle was used in the determination of buffering capacity. These are young athletes with a low percentage body fat. The mean VO2max was 63.6 +/- 2.9 ml X kg-1 X min-1. The anaerobic capacity is striking with the mean AST time of 114.3 +/- 16.3 seconds and post-AST lactate values of 22.0 +/- 1.4 mmol X l-1. The skeletal muscle buffering capacity was elevated above normal by 50% indicating an enhanced capability of resisting changes in intracellular pH which may affect performance.
