This study intends to examine the effect of a commercially available nutritional supplement, Beta-hydroxy-beta-methylbutyrate(HMB) on whole-body responses to a sugar load.

One change associated with human aging is a reduction in "fitness", both in terms of how far or quickly a person can run/cycle/swim and also in how well their blood vessels work. Additionally a person's metabolic fitness decreases; this is how well the body copes with nutrition and is why, for example, older people have a higher risk of diseases like type 2 diabetes. Previous studies have shown that as people become less fit, they are at increased risk of suffering a complication whilst undergoing surgery. It has also been shown that measuring how fit someone is, is better at predicting the risk of a surgical complication than purely using a person's age alone. Lots of research has shown that exercise can potentially reverse some of the age-related declines in fitness, however most has used long sessions of continuous exercise over a long period of time. High-intensity interval training (HIT), whereby people cycle on an exercise bike very hard for a minute, followed by a short rest, repeated over the course of 15 minutes can rapidly improve a person's fitness. However not everyone will be able to, or indeed want to participate in exercise this strenuous; therefore this research seeks to explore whether other options, such as dietary supplements can improve aspects of fitness

This study intends to examine the effect of giving a dietary supplement on the way a person's body handles the glucose (from carbohydrates/ sugars) in a meal. Previous work has shown that taking a beta-hydroxy beta-methyl butyrate (HMB) supplement may improve may improve a patient's response to glucose, however the evidence is not clear. HMB is a commercially available nutritional supplement providing a compound that the body produces each time protein is consumed, and is most commonly used by bodybuilders to help gain muscle.

Inclusion Criteria:

• Healthy volunteers
• Aged 18-35 or 65-85
• Male

Exclusion Criteria:

• Current participation in a formal exercise regime

• A BMI < 18 or > 32 kg·m2

• Active cardiovascular disease:

  o uncontrolled hypertension (BP > 160/100), angina, heart failure (class III/IV), Significant arrhythmia, right to left cardiac shunt, recent cardiac event

• Taking beta-adrenergic blocking agents,

• Cerebrovascular disease:

  o previous stroke, aneurysm (large vessel or intracranial), epilepsy

• Respiratory disease including:

  o pulmonary hypertension, significant COPD, uncontrolled asthma,

• Metabolic disease:

  o hyper and hypo parathyroidism, untreated hyper and hypothyroidism, Cushing's disease, type 1 or 2 diabetes

• Active inflammatory bowel or renal disease

• Malignancy

• Clotting dysfunction

• Significant musculoskeletal or neurological disorders

• Family history of early (<55y) death from cardiovascular disease