#SciBraaiSides 24 October 2014

After a short break, Scibraai Sides are back, with thoughts about mountain biking and mediation on the one side, and diabetes and the use of Vitamin A supplements in children.

Put some science behind your MTB tyre talk

Fat_Mountainbike_Tires_by_g3niuzWhen next you and your mountain bike buddies have a discussion about which to use – 26in. or 29in. wheels – put some science behind your arguments.

And you have Wynand Steyn and Janike Warnich of the University of Pretoria to thank for it. In an article in the South African Journal for Research in Sport, Physical Education and Recreation, they investigating tyre-road rolling resistance to see how it affects the performance of a cycle – and of course the cyclists who rides it.

“As rolling resistance is indicative of the behaviour of a vehicle over specific terrain, it can be viewed as an objective parameter to compare the relative performance of these two wheel sizes,” believes Steyn.

The researchers used coast-down tests to evaluate the rolling resistance of four mountain bikes as affected by wheel diameter and terrain type, cyclist mass, tyre inflation pressure and suspension type.

They found that the average rolling resistance of the 26in. diameter wheel was higher than that of the 29in. diameter wheel. Also, sand surfacing has the highest rolling resistance coefficient. Terrain surface has the largest effect on rolling resistance coefficients measured, followed by the cyclist mass, wheel diameter and tyre inflation pressure.

“The best combination for maintaining momentum after traversing over an obstacle was high tyre inflation pressure, low cyclist mass and full suspension 29in. wheel diameter option,” adds Warnich.

Reference: Steyn, W.J. VdM. & Warnich, J. (2014). Comparison of tyre rolling resistance for different mountain bike tyre diameters and surface conditions, South African Journal for Research in Sport, Physical Education and Recreation

Rethink how kids get Vitamin A in, asks UWC researcher

Keratomalacia – Vitamin A deficiency ulcer. © International Centre for Eye Health www.iceh.org.uk, London School of Hygiene & Tropical Medicine.

There isn’t real value in the policy to provide high-dose Vitamin A capsules to children. Instead, the focus should shift towards increasing children’s regular intake of vitamin A by fortifying food or through giving regular low-dose supplements.

So says a team of researchers in the International Journal of Epidemiology, led by John Mason of Tulane University in the US. David Sanders of the School of Public Health at the University of the Western Cape is one of the co-authors.

Vitamin A is found in dairy products, fish, darkly colored fruits and vegetables. Prolonged Vitamin A deficiency can lead to xerophthalmia (dry eye) and ultimately to night blindness or total blindness, as well as to skin disorders, respiratory disorders, infections such as measles and diarrhea. Such deficiencies remain a concern in especially developing countries where malnutrition is common, and can affect up to one-third of children.

The researchers say that the prevalence of vitamin A deficiency has only fallen slowly over the past 20 years. This is despite the extensive distribution and administration of periodic (4– to 6-monthly) high-dose VA capsules to about 80% of all children in developing countries. This massive programme was motivated largely by an expectation of reducing child mortality, stemming from findings in the 1980s and early 90s.

“Efficacy trials since 1994 have in most cases not confirmed a mortality impact of VA capsules,” says Mason. “Only one large scale programme evaluation from India has ever been published, which showed no impact on 1–6–year-old mortality.”

The researchers believe there is no longer any evidence that intermittent high-dose VA programmes are having any substantial mortality effect, perhaps due to changing disease patterns among for instance measles. They propose that the frequent intakes of vitamin A in physiological doses (e.g. through food-based approaches, including fortification, and through regular low-dose supplementation) should rather be considered.

“A policy shift is needed, based on consideration of current evidence,” Morgan stresses. “A prudent phase-over is needed towards increasing frequent regular intakes of VA at physiological levels, daily or weekly, replacing the high-dose periodic capsule distribution programmes.”

Reference: Mason, J. et al. (2014). Vitamin A policies need rethinking, International Journal of Epidemiology

Deep breaths, let’s meditate for health’s sake

Phra_Ajan_Jerapunyo-Abbot_of_Watkungtaphao.So, is there more to meditation techniques such as Ratio Breathing, Transcendental Meditation and Zazen than just deep breathing? Are there any benefits in it for health and sport fanatics?

Yes, says a team of researchers in an article in the South African Journal for Research in Sport, Physical Education and Recreation, after investigating the neurophysiological, psychological, sport and health dimensions of these three meditation techniques. The lead author is Richard Buscombe of the University of East London in the UK, while Stephen Edwards and David Edwards, both from the University of Zululand, are among the co-authors.

Seven men and two women who actively compete across a range of individual and team sports took part in the research. They had never before used meditation techniques or practices in their sporting or daily lives.

“Integrative findings support the value of all three meditation conditions for health and to a lesser extent for sport, especially with regard to their effect on focus,” says Buscombe. “All three meditation conditions were associated with a decrease in respiration.”

Participants valued Ratio Breathing for its effect on concentration, Transcendental Meditation for its depth of meditation and Zazen for its effect on self and how removes participants from external distractions. A lowered respiration rate was seen in the Ratio Breathing group, increased physical relaxation and alpha activity (dee8p relaxing wakefulness) in the Transcendental Meditation group, and increases in both alpha and theta (light meditation and sleeping brainwaves) activity in the Zazen group.

Reference: Buscombe, R. et al (2014). Neurophysiological, psychological, sport and health dimensions of three meditation techniques, South African Journal for Research in Sport, Physical Education and Recreation


Africa needs to make plans to deal with imminent rise in diabetic children

1280px-Blood_Glucose_Testing_-_Kolkata_2011-07-25_3982The majority of African countries still have a low incidence of diabetes in children, but this will most probably increase in the years to come. It is therefore essential that governments develop sustainable policies to deal with such increases.

So says Nelia Steyn Zandile Mchiza and Andre-Pascal Kengne of the University of Cape Town and the
Non-Communicable Disease Research Unit of the Medical Research Council, after reviewing the occurrence of diabetes mellitus among children and young people on the continent. The review is published in Expert Review of Endocrinology & Metabolism.

“There is a paucity of data with regard to the burden of disease, prevalence of undiagnosed diabetes, healthcare and acute and chronic complications,” notes Steyn. “Furthermore, access to care remains an issue of great concern.”

The researchers recon that in the next 5 years, more research will be undertaken on the burden of the disease and on interventions to provide better access to care. This study considered both Type 1 (insulin-deficient) and Type 2 (insulin-resistant) diabetes.

Reference: Steyn, N.P. et al (2014). Review: Future challenges for pediatric diabetes management in developing countries: lessons from Africa, Expert Review of Endocrinology & Metabolism




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