TM Issue 15

Page 68

WENDY SWEET

Why fitness matters Understanding the difference between “activity” and “fit”

As

the New Zealand government tries to mitigate obesity and diabetes in our children, it is timely to remind health and PE teachers of the health benefits of “improved fitness.” I use the term “fitness” purposively. It is a term that is absent from the youth obesity and diabetes discourse, as the preferred terms “physical activity and movement skills” have prominence. Yet, the difference between being “physically active” and “physically fit” is important from a bio-medical perspective. The changes that accrue from a certain “dose” or Frequency, Intensity, Time and Type (The FITT Principle, taken from the pioneer of exercise physiology, Robert Fitt’s) of cardiovascular and strength activities elicit a metabolic “response” that eventually contributes to physiological improvements in the cardiovascular system and skeletal muscle. The adaptations that occur from a progressive and accumulative approach to better fitness enable morphological improvements in cardiac and skeletal muscle, which decreases diabetes and obesity.

Teachers Matter

R.H. Fitts, an exercise physiologist, shaped much of the current thinking regarding exercise training and “dose-response” relationships in the ’70s. Fitts and other exercise physiologists found that exercise duration as well as intensity resulted in positive changes in muscle oxidative capacity. This is an important issue for heath and PE teachers to re-visit, as it is the impairments in skeletal muscle mitochondrial function and lipid (fat)

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oxidation that are known to play a significant role in metabolic problems such as insulin resistance, obesity and Type 2 diabetes. As well, new research on strength training also shows a protective role in Type 2 diabetes, although how this occurs is not fully understood. Understanding the role of the mitochondria is essential for anyone involved in promoting and supporting cardiovascular and musculoskeletal fitness gains. Mitochondria are organelles within skeletal muscle that can impressively boost a muscle’s capability to burn fat, improve insulin sensitivity, minimize fatigue and enhance capacity to synthesize fuel for physical activity and exercise (Menshikova et al., 2007). Kravitz reports that those who participate in regular endurance exercise increase the density and size of the mitochondria thus improving their ability to utilise more fat and use less carbohydrate for fuel during exercise. A secondary effect is the reduction in metabolic acidosis (lactic acid) produced in the muscles enabling the exercising body to do more work, experience less fatigue and burn more calories with each workout. All of these capabilities by the mitochondria are referred to as “mitochondrial biogenesis.” The question: How much exercise is enough to produce these necessary biological changes? Va n d e r H e i j d e n ’ s 2 0 0 9 s t u d y o f cardiovascular training in obese postpubescent youth provides some insight into the intensity debate. Twenty-nine subjects

(both male and female) underwent 12 weeks of supervised aerobic training (four sessions of 30 minutes each session) and wore heart rate monitors in an attempt to keep them exercising at an intensity of 70 percent of their aerobic capacity, a moderate intensity. The control group was lean subjects. The findings supported a 14 percent decrease in insulin concentration in the obese group compared to only 8 percent in the lean group; 3 percent decrease in percentage body fat in the obese group, and no change in the lean group. In a study of previously sedentary adults, Menshikova et. al (2007) also showed that moderate intensity aerobic exercise, four to six times per week and progressing from 30 – 40 minutes per session for 16 weeks resulted in significant mitochondrial biogenesis adaptations. The obese subjects in this study were also placed on a 25 percent calorie reduction diet. They averaged a 7 percent loss in body weight.

Fitness and academic achievement Studies involving public school students in California found a distinct connection between fitness and ability in reading and maths. Higher achievement was associated with higher levels of fitness, and the relationship between fitness and mathematical achievement was strongest.


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Articles inside

Why fi tness matters

13min
pages 68-76

Which language do you speak the most?

5min
pages 62-63

Kaore or kaore ano - No or Not yet?

2min
pages 52-53

How does your face rate on Facebook?

2min
pages 56-57

Telling it how it is: Does the truth have to hurt?

5min
pages 60-61

Spring entertaining

5min
pages 58-59

How rock ‘n’ roll saved loads of time

2min
pages 54-55

The nature of school

5min
pages 50-51

Test Yourself

18min
pages 34-42

Growing through mistakes

4min
pages 48-49

The alarm you’ll look forward to: iStudyAlarm

1min
page 47

Are you a half tank pike?

6min
pages 43-44

Top 10 trends for schools

5min
pages 32-33

Make time your ally

7min
pages 45-46

The seven phases of values development

10min
pages 26-29

Hidden infl uences on student learning

5min
pages 16-17

The 3 metre rule

3min
pages 14-15

Five “F” Factors

6min
pages 30-31

Understanding counterwill

3min
pages 12-13

Thinking interdependently

3min
pages 22-23

Formative assessment: It’s all about process

8min
pages 24-25

Upgrading your in-house leadership development

6min
pages 10-11
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