The Effects of Displacing Sedentary Behavior With Two Distinct Patterns of Light Activity on Health Outcomes in Older Adults (Implications for COVID-19 Quarantine)

Abstract

Rationale: The COVID-19 pandemic is limiting outdoor and community-based activities, especially for older adults owing to the requirement for self-isolation, potentially increasing prolonged sedentary behavior (SB). Given a poor tolerance for intense exercise, SB displacement with light intensity physical activity (LIPA) is a promising health enhancing alternative. Therefore, the aims of this study were to investigate the effects of two different types of SB displacement on health outcomes in older adults and any differential impact of associated LIPA pattern. Method: 28 older women (age: 73 ± 5 years, height: 1.60 ± 0.07 m, weight: 67 ± 10 kg, and BMI: 26.1 ± 3.6 kg/m²) underwent overnight fasted dual energy x-ray absorptiometry (DEXA) imaging, blood sampling, and functional assessments before being randomly allocated to one of two groups: (1) single continuous bout of 45-50 min LIPA daily (n = 14); or (2) SB fragmentation (SBF; ~48 min LIPA daily, 2 min LIPA for every 30 min of SB; n = 14). Compliance was systematically monitored using tri-axial accelerometery. All measures were taken at weeks 0 and 8. Results: Physical behavior significantly altered (decreased SB/increased LIPA; p < 0.05) and to a similar extent in both groups. We observed a significant reduction in serum triglycerides [p = 0.045, effect size (ɳ_p ²) = 0.15; SBF: -0.26 ± 0.77 mmol/L, LIPA: -0.26 ± 0.51 mmol/L], improved 30 s sit-to-stand (STS) count (p = 0.002, ɳ_p ² = 0.32, 2 ± 3 STS) and speed (p = 0.009, ɳ_p ² = 0.35, -10 ± 33%), as well as increased average handgrip strength (p = 0.001, ɳ_p ² = 0.45, 6 ± 12%), and gait speed (p = 0.005, ɳ_p ² = 0.27, 0.09 ± 0.16 m/s) in both groups. Interestingly, SBF caused a greater increase in peak handgrip strength (8 ± 14%), compared to LIPA (2 ± 10%; p = 0.04, ɳ_p ² = 0.38). Conclusion: SB displacement induced significant improvements in fasting triglycerides, gait speed, as-well as STS endurance/speed in older women. Frequent vs. continuous SB displacement also caused greater increases in handgrip strength. While both SB displacement protocols display promise as efficacious home-based interventions for self-isolating older adults, our results would suggest a physical functioning advantage of the SBF protocol for certain outcomes.

Keywords: COVID-19; light intensity physical activity; physical functioning; sedentary behaviour; sit-to-stand; triglyceride.

Figure 1

Group dependent changes relative to baseline for physical behaviour outcomes. Panel A represents changes in light intensity physical activity (LIPA), while panel B represents changes in sedentary behaviour.

Figure 2

Group dependent individual changes for hip circumference. Panel A represents individual changes following sedentary behaviour fragmentation (SBF); while panel B represents individual changes following continuous light intensity physical activity (LIPA). *Represents a significant change over time.

Figure 3

Group changes in fasting triglycerides from pre to post intervention. *Represents a significant change over time. The dashed line (- - -) represents the fasting triglycerides threshold (2 mmol/L) below which significantly reduced CVD risk is observed (Iso et al., 2014; Nordestgaard and Varbo, 2014).

Figure 4

Group dependent changes relative to baseline for physical function parameters. *Represents a significant group × time interaction effect. HGS, handgrip strength and STS, sit-to-stands.