Fall risk in relation to strength training, walking, and sitting among women aged 75-105 years: a cross-sectional study within the Women’s Health Initiative Strong and Healthy (WHISH) Intervention Cohort

Background Falls are the leading cause of injury and injury death among older women in the United States. The Women’s Health Initiative Strong and Healthy ( WHISH ) trial intervention cohort provided the opportunity to assess how fall risk classification (FR-ABC), as measured by balance confidence, relates to strength training, walking, sitting, and physical function (PF) in women aged 75 and over, a growing population at particularly high fall risk. Methods We analyzed data from 8,915 women aged 75–105 years (mean age 84.9 ± 5.1 years; 49.6% ≥85 years) randomly assigned to a PA intervention in the WHISH pragmatic trial. Participants self-reported their weekly participation in strength training, walking, daily sitting time, and current PF. Balance confidence was measured using the Activities-specific Balance Confidence (ABC) scale, with an ABC score of < 67% used to classify FR-ABC. We assessed FR-ABC prevalence in the total cohort and for the women aged 75–84 and 85 years and older and cross-sectional associations with strength training, walking, sitting, and PF categories using analysis of variance (ANOVA) and chi-squared tests. Results Mean age was 84.9 years, with 49.6% of participants aged ≥ 85 years. FR-ABC classification was 35.1% overall, 22.7% for women aged 75–84 and 47.4% for women aged ≥ 85 years. Overall, strength training ≥ 2 hours per week was associated with a 34% FR-ABC risk reduction (RR = 0.66, 95% CI: 0.61–0.71); walking ≥ 4.25 hours/week with a 70% FR-ABC risk reduction (RR = 0.30, 95% CI: 0.27–0.33); while, sitting ≥ 8 hours/day was associated with a 41% increased FR-ABC risk (RR = 1.41, 95% CI: 1.33–1.49). High PF (score ≥ 90) was associated with a 91% FR-ABC risk reduction (p < 0.001). Conclusion More strength training and walking, lower sitting time, and higher PF were strongly associated with reduced fall risk classification among women aged 75 years and older. Although these associations were more pronounced among women aged 75–84 year, it was also true for women aged 85 and over. Fall risk prevention should emphasize each of these PA factors.