Table 2.
Prevalence of Frequent Knee Pain in Non-Swimmers compared to Swimmers (dichotomous). Prevalence of frequent knee pain among those participating in 3 levels of activity: low, middle, and high. Results are presented unadjusted and adjusted with 95%CIs.
| Swimming Time Period | Unadjusted Prevalence of Frequent Knee Pain (95% CI) | Adjusted* Prevalence of Frequent Knee Pain (95% CI) |
|---|---|---|
| Any History of Swimming | ||
| Non-Swimmers (n = 1567) | 41.2% (38.8 – 43.6%) | 39.9% (37.4 – 42.5%) |
| Swimmers (n = 1055) | 37.2% (34.3 – 40.1%) | 36.4% (33.4 – 39.5%) |
| Low (n = 398) | 39.2% (37.3 – 41.1%) | 37.2% (35.1 – 39.3%) |
| Middle (n = 304) | 37.5% (34.8 – 40.3%) | 36.0% (33.1 – 39.0%) |
| High (n = 353) | 35.8% (31.2 – 40.0%) | 35.9% (31.7 – 40.4%) |
| p for trend = 0.05 | p for trend=0.8 | |
| Ages 12 – 18 years old | ||
| Non-Swimmers (n = 1889) | 40.5% (38.3 – 42.7%) | 39.4% (37.1 – 41.8%) |
| Swimmers (n = 733) | 37.2% (33.8 – 40.8%) | 36.5% (32.9 – 40.2%) |
| Low (n = 295) | 39.1% (37.0 – 41.2%) | 36.0% (33.8 – 38.4%) |
| Middle (n = 223) | 38.1% (34.7 – 41.5%) | 38.3% (34.7 – 42.0%) |
| High (n = 215) | 37.1% (32.1 – 42.3%) | 37.2% (32.0 – 42.7%) |
| p for trend = 0.3 | p for trend=0.8 | |
| Ages 19 – 34 years old | ||
| Non-Swimmers (n = 2107) | 40.7% (38.6 – 42.8%) | 39.6% (37.4 – 41.8%) |
| Swimmers (n = 515) | 35.0% (31.0 – 39.2%) | 34.8% (30.6 – 39.2%) |
| Low (n = 181) | 37.9% (35.7 – 40.2%) | 37.8% (35.3 – 40.3%) |
| Middle (n = 142) | 35.3% (31.6 – 39.3%) | 32.9% (29.1 – 37.0%) |
| High (n = 192) | 32.8% (27.5 – 38.6%) | 33.7% (28.1 – 39.8%) |
| p for trend = 0.02 | p for trend=0.2 | |
| Ages 35 – 49 years old | ||
| Non-Swimmers (n = 2215) | 39.8% (37.8 – 41.9%) | 39.0% (36.8 – 41.1%) |
| Swimmers (n = 407) | 38.0% (33.5 – 42.9%) | 37.2% (32.4 – 42.3%) |
| Low (n = 143) | 38.7% (36.3 – 41.3%) | 37.4% (34.7 – 40.2%) |
| Middle (n = 142) | 37.6% (33.3 – 42.2%) | 35.9% (31.3 – 40.7%) |
| High (n = 122) | 36.5% (30.2 – 43.5%) | 36.3% (29.6 – 43.5%) |
| p for trend = 0.4 | p for trend=0.5 | |
| Ages > 50 years old | ||
| Non-Swimmers (n = 2260) | 39.7% (37.7 – 41.7%) | 38.7% (36.6 – 40.8%) |
| Swimmers (n = 362) | 39.0% (34.1 – 44.1%) | 38.4% (33.3 – 43.8%) |
| Low (n = 132) | 39.2% (36.6 – 41.8%) | 39.5% (36.6 – 42.5%) |
| Middle (n = 115) | 38.6% (34.0 – 43.4%) | 37.7% (32.8 – 42.8%) |
| High (n = 115) | 38.1% (31.3 – 45.4%) | 37.8% (30.6 – 45.5%) |
| p for trend = 0.7 | p for trend=0.8 |
*
Adjusted for age, sex, BMI, BMI at age 25, history of knee injury, and all other leisure activities correlated with swimming during the respective age ranges.