Exercise as it relates to Disease/Exercise Prescription for the control of Metabolic Syndrome

Brief Background
Metabolic Syndrome (MetS) or Syndrome X affects up to 1 in 3 Australians, being an interrelation of many distinct metabolic irregularities, especially the associated increase in Type 2 Diabetes and Cardiovascular Disease. There are a number of interventions/treatments, with exercise interventions reducing prevalence and negative outcomes.

Prevalence
Australian prevalence (hard to define due to it’s varying symptoms and definitions) is ~ 29-33%, however numerous sources show increases in the prevalence of the overweight and obese (64.1% of women, 74.1% of men ) and an increase in the diagnosis of Type 2 Diabetes. This translates directly into a high (increasing) prevalence of MetS, greater in men than women, steadily increasing from the age of 25, and progressively increasing as waist circumference increases.

Causes and Symptoms
The disease state is also known as Insulin Resistance Syndrome, Metabolic Syndrome X, or simply Syndrome X due to the interrelation of the many key physiological factors, which can be seen in the following table:

Focus of Intervention/Treatment
The primary focus for the treatment/prevention of MetS is manipulation of lifestyle (such as a change in diet, weight loss, quitting smoking, reduction in stress levels, pharmaceutical use and potentially surgery) and exercise levels; the primary concentration being treatment of obesity (due to the high correlation/direct relationship MetS has to central/visceral obesity), seconded by improvement of Insulin resistance.

Exercise
Up to 20% of Australians are classed as physically inactive, or insufficiently active (36% ) and low aerobic exercise capacity appears to be the strongest predictor of mortality from MetS. Regular exercise leading to weight loss is key for positively altering insulin resistance, and glucose response,  but also for influencing a number of other MetS features.

Aerobic Exercise
Aerobic exercise is optimal, due to its high correlation to a reduction in abdominal (or visceral) adiposity, and as aerobic physiological adaptations are highly beneficial specifically: Type of aerobic activity varies, American College of Sports Medicine (ACSM) suggesting that sessions of continuous sub-maximal activity are best for controlling MetS, but other sources  show that greater response is seen when a frequent change in intensity was introduced i.e. aerobic interval training.
 * As an anti-inflammatory reducing metabolic stress.
 * ↓ In inflammatory cytokines (CRP, TNF-α, Adhesion molecules etc) via reductions in visceral fat/initiation of anti-inflammatory environment.
 * ↓ Blood pressure (as much as 11mmHg systolic, 9mmHg Diastolic )
 * ↓ Cardiovascular disease risk.
 * ↓ Blood Glucose levels
 * ↓ Psychosocial stress
 * ↓ Plasma triglycerides
 * ↓ Mean Arterial Pressure (MAP)
 * ↑ Insulin sensitivity in muscle cells
 * ↑ High Density Lipoprotein Cholesterol (↓LDL)
 * ↑ Release of Adrenalin and Cortisol and ↓ in Pro-inflammatory monocytes

Resistance Exercise
Abundant new evidence recommends resistance training should also be considered due to: Resistance training has much less of an effect on total cholesterol levels, HDL, LDL, triglyceride levels, and Diastolic BP. Increases in muscular strength may be imperative in the conservation of lean body mass (particular in the elderly) increasing the general activity level, and adding variety to exercise programs (facilitating adherence).
 * Primarily its impact on skeletal muscle (and its role in the metabolism of triglycerides and glucose)
 * general ↓ in fat mass,
 * ↓ in systolic blood pressure,
 * Improvement in glycaemic control,
 * ↑ Insulin sensitivity (same mechanism as aerobic exercise).

Recommendations
All programs should be tailored to individual needs and capabilities, based on age, fitness level, and any considerable risk factors; see the following. Program for continued, consistent energy expenditure. Whilst weight loss/60% of an individuals 1RM with 8-10 exercises per session). Aerobic exercise above 180 min/week has a “dose-response” effect i.e. ↑ Frequency = ↑ Physiological response. Resistance training is less dose-dependent and ↑ Frequency will not necessarily ↑ response. Three sessions ≥60min/week with an intensity ≥75% maximum heart rate yields best results for aerobic exercise.

Exercise should be predominantly aerobic based to maximise CV adaptations with additional resistance-training components for strength and functional capacity development. Ideally a combination of strength and aerobic, especially aerobic interspersed with regular increases to high intensity (interval training) for a minimum of 12 weeks.

Precautions and Further Resources
Before engaging in any exercise or exercise prescription (especially "at risk" populations/individuals), it is recommended to get checked by a health professional, as well as undertaking specific Pre-Exercise screening tools (such as the ESSA Screening system). ESSA Screening Tool and Information

ESSA - Metabolic syndrome and Exercise fact sheet

International Diabetes Foundation Metabolic Syndrome

ACSM Factsheet - Lifestyle and Metabolic Syndrome

Nutrition Australia - Metabolic Syndrome

see also these previous metabolic syndrome focused wikibooks: Short Duration Exercise, Aerobic Exercise.