Being south Asian or centrally obese may be associated with an increased risk of inflammation. The investigators are seeking to investigate whether this is the case by recruiting white European and south Asian men who are lean or have central obesity. Further, the investigators wish to investigate whether physical activity influences the associations.

Central obesity is associated with an increased risk of cardiovascular disease. Further, south Asians have been shown to be at an increased risk of cardiovascular disease compared to white Europeans.

Cardiovascular disease is underpinned by inflammation. Evidence suggests that people with obesity have a more pro-inflammatory and pro-migratory monocyte profile compared with individuals who are lean. The excessive monocyte migration contributes to metabolic dysfunction over time, increasing the risk of chronic disease. However, there is no evidence in south Asians.

One modifiable risk factor which may be able to influence this is physical inactivity, with higher levels of physical activity being associated with reduced inflammation. However, although south Asians are more at risk of cardiovascular disease than white Europeans, evidence suggests south Asians are also less physically active than white Europeans.

The investigators are looking to recruit south Asian and white European men who are lean or have central obesity to investigate 1) is there an association between ethnicity and the tethering and migration of pro-inflammatory monocytes? 2) is there an association between central obesity and the tethering and migration of pro-inflammatory monocytes, and is there an interaction with ethnicity? 3) do higher levels of physical activity influence the tethering and migration of pro-inflammatory monocytes, and is this influenced by ethnicity or central obesity?

To investigate this, the investigators are looking to recruit south Asian and white European men who are either centrally obese or lean. The investigators require 1 blood sample and the participants to wear an activity monitor for 7 days.

Peripheral blood mononuclear cells (PBMCs) will be isolated from the whole blood sample. Then, the investigators will quantify the migratory capacity of PBMCs to a fixed chemokine gradient over time. Further, the investigators will phenotype the monocytes to indicate the characteristics of the monocytes that migrate towards the chemokine mix.

The activity monitor will quantify habitual physical activity, which will be used in the statistical analyses to investigate whether physical activity may influence the response.

It is important to investigate as it will further scientific knowledge on the underpinnings of chronic disease and enable a better understanding on the role of physical activity to potentially reduce the risk.

Inclusion Criteria:

• Non-smokers (including vaping)
• Not currently dieting

Exclusion Criteria:

• Musculoskeletal injury that has affected normal ambulation within the last month;
• Any muscle or bone injuries that influence physical activity
• Free from heart conditions and blood disorders
• Weight fluctuation greater than 3kg in the previous 3 months
• Taking anti-inflammatory medication

All participants will be recruited from the local community using advertisements published online and across local facilities and shops.

Anonymised individual participant data for all primary and secondary outcome measures will be made upon request.

The data will be available 6 months after publication for 12 months.

Data will be available to other researchers who would like to run the same statistical methods we have used to check the interpretation of results.