Special pops Children essay Flashcards
General structure
Intro Trend Health consequences Conc to part one - should they increase. Endurance training HIIT training The best way to implement Conclusion
Describe the trend in CRF
Despite anecdotal comments regarding a decrease in CRF in children in the UK, direct measures of peak VO2 suggest this may not be the case. however most data are from compilations of small studies, potentially not representative of actual trends and are mostly from the late 20th century (Armstrong 2012). Despite this, for unknown reasons performance tests, such as the 20m shuttle run test (20mSRT), have decreased by around 13% over the last 35 years globally which may explain observations of decreasing fitness.
Describe health consequences of low CRF
Although no clear trend in cardio-respiratory fitness (CRF), low CRF could have negative health consequences. Evidence from the European Youth Heart Study suggests that CRF is more strongly associated with cardiovascular risk factors including blood pressure and plasma levels of insulin, glucose, triglycerides and total cholesterol, than physical activity (Hurtig-Wennlof et al,. 2007). Despite being a cross-sectional study, prone to confounding, making it harder to infer causality, there was a large sample size (597 girls, 528 boys) and measurement included a host of variables. A South Korean cohort study, although perhaps not generalisable to the UK, found that CRF has a negative correlation with overweight/ obese BMI status (Kim et al 2016). Strengths of this study included its size (n=843), its prospective design and adjustment for a range of confounding factors making it more likely to find an accurate reflection of the true relationship.
Describe Conc to part one - should they increase.
Although CRF may not have decreased in children, there is a wide variation in levels (Armstrong 2012) and those with low CRF are likely to have increased cardiovascular risk and BMI. Resultantly it is important that these individuals are identified and measures are taken to improve their CRF. There is a multitude of literature that look at different ways of improving CRF with designs that can be broadly categorised into endurance training and HIIT interventions.
Describe endurance training
Endurance training has been shown to be a means of improving VO2max. One pre-post design study involving 31 sixth grade students who undertook 13 weeks of endurance-type aerobic activities three time a week, found that VO2 max increased by 5.2% (Rowland 1996). However this study was limited by its lack of control group, particularly as VO2max increases with age in children. Despite this the study contained a high percentage of girls (n=20), a group understudied in the literature, measured the intensity that the children worked at (Heart rate monitors) and looked at other marks of CVD risk (although none significant). Other studies confirm that VO2 can be improved from endurance training in both athletic and non-athletic populations (Armstrong and Barker 2011)
Describe HIIT training
As well as endurance training, HIIT can also improve VO2 max.
• Latest systematic review and meta analysis on HIIT to improve fitness in children
○ Costigan et al 2015
§ Stat sig overall effect - large effect size d=1.05
§ Of controlled studies
§ Strengths
□ heterogeneity - non sig meaning they roughly homogenous
-also good for body composition
§ Limitations
□ Variation in control, some obese vs lean, some exercising, some sedentary
□ Fitness not allometrically scaled measure of VO2 - favours lighter children
□ Difference between studies as to %VO2max - should be maximal.
§ Not all stat sig, variation in findings… Lead onto Tjonna
• One stat sig study with impressive findings, Tjonna et al 2009
Compared 2 different trials randomised
One aerobic interval training (4x4min intervals at 90% of maximal HR separated by 3min at 70% x2 a week for 3 months.
One multidisciplinary approach (frequent exercise, dietary and psychological advice at a hospital)
VO2 increased at both 3 months and 12 months in AIT
Range of other markers examined, benefits in AIT over MTG for BMI, BP, regulation of blood glucose and insulin, reinforces positive effects associated with VO2.
Strengths
Attendence criteria for inclusion was set to minimum 80%
Follow up at 12 months
Limitations
Obese and Overweight children
Best way to implement?
he best way to implement a CRF intervention
○ HIIT or endurance?
§ HIIT may be beter as:
□ (start with neg) HIIT sustainable in logn term? Injury, motivation, enjoymentTime efficiency, Enjoyment, sports performance, explosive power, body comp (Tolfrey and Smallcombe 2017)
□ However the extent is limited/ varied,
□ Evidence suggests that children need a higher exercise intensity than adults in order to improve fitness (Armstrong & Barker 2011), HIIT more closely resembled the intermittent nature of children’s habitual PA and that children may enjoy and be more engaged in HIIT than Moderate-intensity continuous exercise.
○ Other factors
§ Duration
□ >8 weeks had sig effect on body comp, Costignan 2015 (not for fitness)
§ IN line with expert statements at least 3 sessions per week, 85 to 90% of maximum heart rate, 30 to 60 min duration, and lasting at least 3 months (Tolfrey et al, 2012 (BASES))
§ Who to target?
□ Baseline fitness inversely associated with improvement in VO2 (Resaland 2011) (Tolfrey 2012 BASES), interventions targeting this group even more improtant. Max impact per child targetted
□ Many cutoffs for fitness, no consensus over which is best, however they are similar values. One set of cutoff proposed by Adegboye et al. (2011)
® Statistical analysis used to determine a threshold, below these there is a higher risk of cardio-metabolic disease
® Large sample of 4,500
® Lots of outcomes - related to metabolic syndrome and CVD.
® Largescale cross-sectional evidence - European Heart study
□ Pratically, use a pratical population level measure of fitness such as the 20m shuttle run test (20-mSRT) then use diresct measurement of peak VO2 on those with boarderline/ low fitess. In line with expert (Tolfrey et al, 2012)
Conclusion
• Limtations - Cost effectiveness - vs PA intervention Unclarity implementation of HIIT. • More research • Due to the prevalence of individuals with low fitness in the UK and the negative associated concs recommend x
