Weighted vest use or resistance exercise to offset muscle loss in older adults: secondary findings from the INVEST in bone health RCT.

All three intervention groups achieved similar and significant weight loss of approximately 10% over 12 months.

• 150 participants were randomized to WL, WL + RT, or WL + VEST (50/group)
• Participants were 66.4 ± 4.6 years, 75% female, 69% white
• 85.3% were living with obesity and 14.7% with overweight
• Weight loss was ~10% across all groups with no significant between-group differences

WL + RT increased mid-thigh muscle cross-sectional area at 12 months.

• WL + RT increased mid-thigh muscle CSA by 0.5% (p < .05)
• This improvement was observed relative to the WL-only group
• CT was used to assess muscle CSA at baseline, six-, and 12-months
• Group comparisons showed improvements for WL + RT over WL

WL + RT significantly improved muscle density at 12 months.

• WL + RT improved muscle density by 3.7%–5.9% (p < .03)
• Muscle density was assessed via CT at mid-thigh
• Improvements in muscle density indicate improved muscle quality
• WL + VEST showed a trend toward improved trunk muscle density of 4.2% (p = .08) compared to WL

WL + RT significantly reduced intermuscular adipose tissue (IMAT) at 12 months.

• WL + RT reduced IMAT by 20%–22% (p < .05)
• IMAT cross-sectional area was assessed using CT
• Reductions in IMAT indicate improved muscle composition
• WL + VEST had minimal impact on IMAT compared to WL alone

WL + RT reduced fat masses measured by DXA at 12 months.

• WL + RT reduced fat masses by 22%–26.8% (all p < .061)
• Fat mass was measured using dual-energy x-ray absorptiometry (DXA)
• Scans were conducted at baseline, six-, and 12-months
• Differences between WL + VEST and WL were insignificant for fat mass outcomes (all p > .05)

WL + VEST showed a trend toward trunk muscle preservation and improved density compared to WL alone but had minimal impact on other measures.

• WL + VEST showed a trend toward improved trunk muscle density of 4.2% (p = .08)
• Differences between WL + VEST and WL were insignificant for all outcomes (all p > .05)
• WL + VEST had minimal impact on muscle CSA, IMAT, lean mass, or fat mass compared to WL
• Weighted vest use did not produce significant benefits comparable to resistance training

Greater weight loss was correlated with increased muscle density but reduced muscle CSA and IMAT, indicating improved muscle quality but reduced muscle quantity.

• Weight loss correlated with increased muscle density (r < 0, p < .001)
• Weight loss correlated with reduced muscle CSA (r > 0, p < .001)
• Weight loss correlated with reduced IMAT (r > 0, p < .001)
• Partial Pearson's correlations were used to examine relationships between weight change and CT/DXA outcomes
• These findings indicate weight loss improves muscle quality while simultaneously reducing muscle quantity

The INVEST in Bone Health Trial used a 12-month randomized controlled design with CT and DXA to assess musculoskeletal outcomes.

• 150 participants were randomized to 12 months of WL, WL + RT, or WL + VEST
• CT assessed muscle and IMAT cross-sectional area and density
• DXA measured lean and fat mass
• Scans were performed at baseline, six-, and 12-months
• Mixed linear models were used to evaluate changes and treatment effects