Effects of Five Days of Physical Inactivity on Endothelial Function in Healthy Humans

Physical inactivity is a significant predictor of major non-communicable diseases such as type 2 diabetes (7%), cardiovascular disease (6%), musculoskeletal disorders and some types of cancer, and has been proposed to be the 4th leading cause of death worldwide. The investigators aim is to assess the vascular (endothelial) function before and after a 5-day period of reduced activity of upper and lower limbs via an arm sling and daily step counts reduction, respectively, in healthy participants. Twelve young (ages of 18 - 35 years), healthy, males and females, recreationally active with a body mass index between 18 and 27 kg/m2 will be recruited. The participants will then randomly undergo two 5-day interventions: (A) 5 consecutive days of habitual daily levels of physical activity and matched food intake (Control trial). (B) 5 consecutive days of reduced step count by 80% compared to the Control trial combined with their non-dominant arm placed in a sling and a reduction in food (energy) intake (~20%) to match the reduction in energy expenditure induced by inactivity (Inactivity trial). On days 1 and 6 of each experimental trial, the endothelial function of the brachial and popliteal arteries, and hand grip strength will be measured.

Study Overview

• Status: Completed
• Conditions: FMD
• Intervention / Treatment: Behavioral: Inactivity

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Nottinghamshire
    • Nottingham, Nottinghamshire, United Kingdom, NG7 2RD
      • The University of Nottingham

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Non-smoking
• Males
• Age (18-35 years old)
• Body mass index (BMI) of 18-27 kg/m2
• Recreationally active
• Ability to give informed consent

Exclusion Criteria:

• Smoking
• Any metabolic (e.g. diabetes), endocrine (e.g. hyperthyroidism) or cardiovascular (e.g. heart or blood) abnormalities including hypertension or heart failure
• Clinically significant abnormalities on screening including ECG abnormalities
• Taking routine medication that may alter cardiovascular function and blood flow (e.g. blood pressure-lowering drugs or drugs that cause hypertension)
• Well-trained individuals
• On an energy-restricted diet or seeking to lose weight
• High alcohol consumption (<3-4 units/day)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control; 5 consecutive days of normal daily levels of physical activity and matched food intake
Experimental: Inactivity; 5 consecutive days of reduced step count by 80% compared to the Control trial, whilst placing the non-dominant arm in a sling, and reduced food intake (~ 20%) to match the reduction in energy expenditure induced by inactivity	Behavioral: Inactivity; On days 1 and 6 of each main trial, the participants will be asked to attend the laboratory after an overnight fast of at least 8 to 12h to undergo brachial and popliteal arteries FMD measurements (30 min apart) using duplex-Doppler ultrasound, followed by assessment of the hand grip strength of their non-dominant hand using a hand dynamometer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline of flow-mediated vasodilatation (FMD) of the brachial artery	The FMD of the brachial artery will be measured using an ultrasound collected at baseline and continuously for 80 seconds post-arm occlusion for 5 minutes	Over 6 minutes and 20 seconds on day 1 and day 6 of each study arm
Change from baseline of flow-mediated vasodilatation (FMD) of the popliteal artery	The FMD of the popliteal artery will be measured using an ultrasound collected at baseline and continuously for 80 seconds post-arm occlusion for 5 minutes	Over 6 minutes and 20 seconds on day 1 and day 6 of each study arm

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hand grip strength	The hand grip strength will be measured using a hand dynamometer. Three maximum hand grips separated by one minute rest at the end of each visit.	3 minutes

Collaborators and Investigators

• Sponsor: University of Nottingham

Study record dates

Study Major Dates

• Study Start (Actual): November 1, 2018
• Primary Completion (Actual): March 1, 2020
• Study Completion (Actual): March 1, 2020

Study Registration Dates

• First Submitted: November 19, 2019
• First Submitted That Met QC Criteria: December 12, 2019
• First Posted (Actual): December 16, 2019

Study Record Updates

• Last Update Posted (Actual): February 23, 2022
• Last Update Submitted That Met QC Criteria: February 4, 2022
• Last Verified: February 1, 2022

More Information

Terms related to this study

• Other Study ID Numbers: A90355

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No