Table 1.

Table showing the studies included in the systematic review and the key findings.

References	Country	Objective	Design	Participants	Method	Sedentary behaviour measurement	Key findings	Physiology
Obesity
Megan Crowe et al.9	Canada	To find out the risk associated with combined MVPA and screen time on overweight or obesity	Cross-sectional study	9913 students of 7–12 grades	MVPA (active >60 min/day; inactive <60 min/day) and sedentary (>2 h of screen time; not sedentary (<2 h of screen time) were related with overweight and obesity	Sedentary > 2 h screen time/day; not sedentary < 2 h/day (questionnaire)	The inactive and sedentary the group was likely to have overweight or obesity than the active and not sedentary group (OR = 1.71; 95% CI, 1.26–2.32)	The body composition and energy expenditure were the possible reasons
Saeidifard et al.10	USA	To find out the differences in EE between sitting and standing	Systematic review and meta-analysis	46 studies (1184 participants)	The literature was searched until June 2017 for studies involving EE between sitting and standing in non-pregnant adults	EE was measured using accelerometers and indirect calorimeters	The mean difference in EE between standing and standing was 0.15 kcal/min (95% confidence interval (CI) 0.12–0.17)	Sitting reduces muscle recruitment and reduces the EE. Postures other than sitting improves NEAT and reduces obesity
Henson et al.11	United Kingdom	To examine associations between sedentary time and adiposity	A nested study from a large RCT	124 participants at the risk of diabetes	Accelerometers objectively measured sedentary time and MRI measured adiposity	Accelerometer (Actigraph)	Sixty minutes of sedentary time was adversely associated with 1.74 L higher total abdominal fat, 0.62 L higher visceral fat, 1.14 L higher subcutaneous fat, and 1.86% higher liver fat.	Partially explained by excess visceral fat, in which non-esterified fatty acids (NEFA), glycerol, and hormones released from adipose tissue
Cardiovascular diseases
Lavie et al.12	USA	To establish the relationship between cardiovascular outcomes and physical inactivity	Scoping review	Heterogenous population. 15 studies (4,58,879 men & 4,66,106 women)	The study reviewed several studies and elaborated the physiological mechanisms relating to chronic diseases and physical inactivity	Heterogenous measurement: subjective and objective measures	• Fit men were found to have reduced mortality by 52% then unfit men • everyone estimated MET increase in CRF was associated with 13% and 15% reductions in all-cause and CVD	Reduced mitochondrial content and respiration, increased inflammation in skeletal muscles, β adrenergic receptor desensitization
Carter et al.13	Netherlands	To review the studies establishing the relation between cardiometabolic risk and prolonged sitting	Scoping review	Eight studies(198 participants)	Several studies were reviewed. The cardiometabolic outcomes were associated with the physical inactivity or prolonged sitting bouts	Not mentioned	Sitting reduces flow-mediated dilatation by 2.2%; inflammatory cytokines increased, endothelial shear 2.2% ± 2.15%	Endothelial stress, cardiac remodelling and endurance, inflammatory markers (IL-6, IL-12), adiposity and atherogenesis
Cancer
Rangul et al.15	Norway	To examine the association between physical activity and sitting time with cancer incidence	Prospective study	8,154 healthy participants from the Norwegian community	adults in the Nord-Trøndelag Health Study (HUNT) followed up for 17–19 years for cancer incidence	Sitting time was measured subjectively through the questionnaire	• sitting ≥eight hr/day was associated with 22% (95% CI, 1.05–1.42) higher risk of prostate cancer compared to sitting <8 h/day. • low physical activity (≤8.3 MET-h/week) had 31% (95% CI, 1.00–1.70) increased risk of colorectal cancer (CRC) and 45% (95% CI, 1.01–2.09) increased risk of lung cancer	Possibly attributed to insulin resistance, adiponectin levels, insulin-like growth factors testosterone, muscle- and fat-related proteins as follistatin, myostatin, activin and inhibin.
Nguyen et al.17	USA	To see whether sedentary behaviour related to colorectal cancer incidence	Cross-sectional study	89,278 women in the Nurses' Health Study II ages 25–42 years	The participants from Nurses' Health Study II ages 25–42 years (1991–2011) were assessed for sedentary behaviour and colorectal cancer	TV viewing time through the questionnaire	If TV viewing hours is more than 7 hours increased the risk of colorectal cancer (RR:1.25). If more than 14 hours of RR increased by 1.69. Inspite of cumulative exercise, prolonged sitting time increases the risk of colorectal cancer	unbroken sitting results in extended exposure to faecal carcinogens, such as secondary bile acids, impair glucose homeostasis and decrease vitamin D levels
Lynch et al.16	Canada	To systematically review studies examining associations of sedentary behaviourwith cancer risk	Systematic review and meta-analysis	176 studies were retrieved investigating the effect on adiposity, sex hormones, inflammation and metabolic function	Literature search on peer-reviewed databases with SB and cancer risk. Also, the study investigated other health risks in cancer survivors.	95% of the studies measured SB through subjective measures	A significant association between SB time and cancer risk factors (OR 1.02 – 1.17). TV times were found significantly related to cancer risk and early mortality	SB increases adiposity, sex hormones, inflammation and metabolic dysfunction predisposing to cancer
Diabetes
Asvold et al.14	Norway	To find whether prolonged sitting is a risk for diabetes	Prospective trial	28,051 adult participants of the Nord-Trøndelag Health Study (the HUNT Study) were followed for diabetes incidence from 1995–1997 to 2006–2008 (11 years)	The trial used the HUNT2 Survey as the baseline risk factor examination. Diabetes risk was assessed at 11 years follow-up Self-reported sitting time	Sitting time was estimated from the questionnaires	• Sitting ≥ eight hr/day was associated with a 17% higher risk of developing diabetes compared with sitting ≤four hr/day. • Without leisure-time physical activity, this risk becomes 30% in participants sitting <8 h/day	Hyperinsulinemia, postprandial hyperglycaemia, impaired glucose tolerance was observed.
Yates et al.18	United Kingdom	To investigate whether prolonged sitting or any interruption alter the postprandial glycemia	Cross over randomized trial	60 participants (30 south Asians and 30 Europeans)	Sitting, sitting with interruptions was administered and postprandial blood glucose was measured	Objective measure through accelerometer (ActivPAL)	insulin response was reduced by 22.4 (12.4, 32.4) mU/L (27%) during walking breaks compared to prolonged sitting	Possible mechanisms were insulin sensitivity and GLUT4 transporters sensitivity
Anxiety and depression
Dale et al.19	Canada	To examine the relationship between physical activity and mental health outcomes	Systematic review	32 studies were included	Studies were searched until 2017 relating physical activity and self-esteem, anxiety and depression	Included both subjective and objective measures of physical activity included	Studies showed physical activity is inversely related to depression, anxiety and directly related to self-esteem	Self-esteem has found to reduce anxiety and depression. Possibly by endorphins and autonomic stability

Supplementary file: Table 2. Breaking Sitting Behavior through Exercises during COVID-19 lockdown.