Exercise as it relates to Disease/Metabolic syndrome and trekking at altitude

Trekking at altitude and metabolic syndrome
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With increased tourism to areas such as the Himalayas, the Andes and other mountain ranges of high altitude, it is important to be aware of the potential risk factors for people with metabolic syndrome so these individuals can properly prepare for the exposure to high altitude hypoxia. Metabolic syndrome definition does change around the world, however the International Diabetes Federation released a paper in 2006 detailing all descriptions around the world and found the main considerations to be someone with hypertension, dyslipidaemia, diabetes or pre-diabetes and central obesity . These four factors are examined below to guide sufferers of metabolic syndrome to the potential risks or benefits of trekking at altitude and offers some recommendations.

Hypertension
The effects of altitude on blood pressure are variable between individuals and dependent on Altitude. For the majority of people blood pressure raises proportional to elevation gain, and is not usually significant until above 3000m.

Potential risks

 * There is initial hypertension, followed by gradual normalization.
 * Needs to be monitored as individuals have shown large increases in B/P.

Potential benefits

 * Possible reduction in B/P with prolonged stay at altitude though evidence varies.

Recommendations

 * Despite these risks, well-controlled hypertension is not a contraindication to high altitude travel or physical activity performed at altitude.
 * To allow for the possible increase in the first few days exposure to altitude, adequate time should be taken to acclimatize properly. Some research has shown improvement after just 2 days, however the longer the exposure the better the acclimatization.

Potential risks

 * Increased risk of Sleep Apnoea, which increases risk of High Altitude Pulmonary Edema.
 * Obesity is positively linked with AMS.
 * The secretion of a number of inflammation-related adipokines is upregulated by hypoxia, and there is a switch from oxidative metabolism to anaerobic glycolysis. Glucose utilization is increased in hypoxic adipocytes with corresponding increases in lactate production.

Recommendations

 * Try to reduce obesity as much as possible before attempting mountain trekking to high altitude to avoid possible complications.

Diabetes
Altitude exposure, including intensive exercise, is not contraindicated for diabetics with good glycaemic control and without vascular complications.

Potential risks

 * Dexamethasone, the most common drug taken on expedition for Acute Mountain Sickness rapidly increases insulin resistance.
 * With increasing altitude, diabetic mountaineers report a reduction in blood glucose control.
 * The combined effects of elevation, temperature, and humidity can render some blood glucose monitors unreliable at moderate to high altitude.
 * Early recognition of poor glycaemic control is difficult at altitude, as symptoms of hypoglycaemia are similar and may be confused with Acute Mountain Sickness.
 * Potential loss of appetite seen at altitude. Diligence needed from diabetics to maintain optimal blood glucose levels.

Potential benefits

 * Significant positive influences have been seen after time at altitude including exercise for improved insulin resistance.

Recommendations

 * To have maximal blood glucose control, precise tracking of energy intake and expenditure, frequent blood glucose monitoring, and flexible insulin dosing are advised.

Dyslipidaemia
No contraindications were found for patients with dyslipidaemia, only potential benefits.

Potential benefits

 * Lower LDL levels seen after trekking and spending time at altitude.
 * High density lipoprotein cholesterol levels are linearly and significantly increased when living at a higher altitude.
 * Lower risk of atherosclerosis and reduced risk of coronary heart disease.
 * Significant increase in HDL cholesterol.

Recommendations

 * Spending time at altitude may enhance control of dyslipidaemia by lowering LDL and increasing HDL.

Potential risks

 * The risk factors increase with increasing altitude.
 * There is evidence to suggest raised risk for AMS for those with metabolic syndrome.
 * Heart rate will be higher at altitude for a given intensity, which must be considered regarding exercise intensity for those with metabolic syndrome.

Potential benefits

 * Some researchers have suggested that high altitude living conditions and activities may possibly be developed as potential natural medicines for the prevention and treatment of type II diabetes and metabolic syndrome.