This study aims to observe participants' physical activity (PA) using a blinded multisensor physical activity monitor as they go about their typical daily physical activities across a 6-week time frame. Participants will also complete a subjective, self-reported, online form to denote structured activities undertaken.

This study will observe participants' objectively measured PA and energy expenditure in a naturalistic manner. Individuals expressing interest will be invited to attend an online familiarisation meeting to assess eligibility for the study - procedures will be presented/explained in detail before participants are given a chance to question and discuss any concerns. Once aware of the requirements, participants will be asked if they wish to take part in the main trial and asked for written informed consent.

In Visit 1 (Day 0) willing participants will then undergo a familiarisation of protocol components, and they will be provided with the SenseWear armband to be worn, constantly, over a 42-day period (except during water-based activities such as showering and swimming). The device does not include a display and so participants are blinded to the measurement. Participants will be instructed to continue with their normal lifestyles and not make any changes. On or around day 43, participants will be asked to return the device (Visit 2).

During visit 1 and visit 2 participants will be measured and weighed using a stadiometer and floor scale. Throughout the trial, weekly reminder emails will be distributed by the research team to all participants reminding them of the study requirements and providing them with an additional opportunity to raise concerns. Due to the data storage capacity of the devices, new monitors will be distributed and used monitors returned remotely via post at weeks 2 and 4.

Additionally, during this period of objective PA measurement, participants will be invited to note the start and end time of any 'structured exercise' - defined as any PA that is "planned, structured, repetitive and aimed at improving or maintaining physical fitness (Caspersen, Powell and Christenson 1985 cited by Simmich, Deacon and Russell 2019)". Participants will also be required to note time spent sleeping. Data from this self-report component of the trial will be used to demarcate bouts of purposeful, structured exercise as well as total self-reported waking time.

Inclusion Criteria:

• Healthy adults aged 40-70.
• Available to attend Department for Health, University of Bath, Bath, UK.
• Capable of conducting typical daily task (e.g., housework, walking etc.).
• Willingness to wear a PA monitor for 24hr for a total of 42 days.

Exclusion Criteria:

• No cold/flu-like symptoms within the last month.
• Smokers.
• Known history of cardiac or circulatory dysfunction.
• Known to live with diabetes or other metabolic disorders.
• Known to live with severe visual or audio impairment.
• Known to live with epilepsy or have seizures.
• Known disabilities that impede daily physical activity.
• Known allergy to nickel.

Participants will be recruited from Bath and surrounding areas (South West, England) although participants able and willing to travel from further afield may be recruited. All participants are aged 40-70 years and healthy (non-clinical sample).