Water-based resistance training raised hip bone density more than band training in older women
In short
In a 32-week randomized controlled trial of 98 overweight women averaging 67.5 years, assigned to land-based elastic-tube training, aquatic resistance training, or control twice a week, only the aquatic group improved Ward's triangle bone mineral density (effect size 0.445) and T-score (0.412) significantly more than both other groups. The remaining hip and lumbar spine measures showed no group differences, so the effect was site-specific. The land comparison used bands, not barbells.
Older women who did resistance training in the pool twice a week for 32 weeks gained more bone density at one part of the hip than women who trained with bands on land. That is the finding of a secondary analysis of a randomized trial in 98 overweight older women.
Who trained, and how?
Participants averaged 67.5 years, with a body mass index of 27.9 and 42.6% body fat. They were split into land-based elastic-tube resistance training (32), aquatic resistance training (33), and a control group (33); both exercise groups trained twice weekly under supervision. Bone mineral content, bone mineral density, and T-score at the hip and lumbar spine were measured by DXA.
Where did the water group come out ahead?
- Ward's triangle BMD — improved significantly more in the aquatic group than in the land and control groups (effect size 0.445).
- Ward's triangle T-score — same direction, aquatic group ahead (effect size 0.412).
- Total hip bone mineral content — showed a time-by-group interaction.
- Everything else — no group differences in the other DXA outcomes, lumbar spine included.
Should you swap the barbell for the pool?
No. The land group in this trial used elastic tubes, not heavy barbells, and the advantage was limited to one small region of the hip. What the result does support is that for older adults who struggle with land-based exercise because of joint pain or body weight, resistance work in water can still give bone a meaningful stimulus — useful if you are a lifter trying to get your parents moving. Water training's effect on fall risk is covered in our aquatic versus land training article, and heavy training for bone density after menopause in our bone density training overview.
This is a secondary analysis of three arms from a six-arm trial, and the trial was registered retrospectively. Read the result as applying to overweight older women.
Frequently asked questions
Can aquatic resistance training improve bone density?
In a 32-week randomized controlled trial of 98 overweight older women, twice-weekly aquatic resistance training raised Ward's triangle bone density and T-score more than land-based band training or control. Other hip and lumbar spine measures did not differ.
What is Ward's triangle?
Ward's triangle is a triangular area inside the femoral neck with relatively sparse bone, reported separately on a DXA hip scan. In this study the benefit of water-based training was limited to that region.
Is water training better for bone than lifting barbells?
This study cannot say. Its land-based comparison used elastic tubes, not heavy barbell training. It supports water training as an alternative for older adults who find land exercise difficult.
How much training did it take to see a bone density effect?
Both exercise groups trained twice a week under supervision for 32 weeks. Whether shorter or lighter programs produce the same effect was not tested.
Source: PubMed