Table 4

Adherence level* analyses of oxidative stress biomarker levels at baseline and 12 months in exercisers and controls in the ALPHA Trial

BaselineTwelve monthsRatio 12 months/baseline (95% CI)‡Per cent change§p Value¶Ptrend**
Geometric mean (95% CI)†Geometric mean (95% CI)†n
SOD (μmol/L/min)
 Controls12.2 (11.9 to 12.6)12.6 (12.2 to 13.0)1551.02 (1.00 to 1.05)2.5Ref.0.26
 <150 min/week12.7 (12.1 to 13.3)12.1 (11.4 to 12.9)400.98 (0.92 to 1.03)−2.50.11
 150–225 min/week12.5 (11.9 to 13.0)12.2 (11.8 to 12.7)660.99 (0.95 to 1.03)−1.10.17
 >225 min/week12.0 (11.3 to 12.6)12.3 (11.7 to 12.8)471.01 (0.96 to 1.06)0.60.54
CAT (μmol/L/min)
 Controls18.9 (17.4 to 20.7)19.5 (17.8 to 21.4)1561.02 (0.96 to 1.09)2.1Ref.0.98
 <150 min/week21.2 (17.4 to 25.9)23.3 (19.2 to 28.5)401.12 (0.99 to 1.28)12.40.19
 150–225 min/week19.4 (16.8 to 22.5)19.4 (16.7 to 22.6)670.99 (0.90 to 1.10)−0.80.63
 >225 min/week22.0 (19.1 to 25.3)22.5 (19.1 to 26.5)471.05 (0.93 to 1.18)4.50.74
8-OHdG (ng/L)
 Controls7.1 (6.8 to 7.3)7.2 (7.0 to 7.5)1531.03 (1.00 to 1.05)2.8Ref.0.78
 <150 min/week6.7 (6.2 to 7.1)7.0 (6.4 to 7.5)401.03 (0.98 to 1.08)−2.50.96
 150–225 min/week7.2 (6.9 to 7.5)7.4 (7.0 to 7.7)671.03 (0.99 to 1.07)−1.10.98
 >225 min/week7.2 (6.8 to 7.7)7.3 (7.0 to 7.7)471.02 (0.97 to 1.07)0.60.71
8-iso-PGF2α (ng/L)
 Controls234 (220 to 250)223 (209 to 239)1430.97 (0.89 to 1.05)−3.2Ref.0.77
 <150 min/week240 (216 to 267)197 (156 to 249)380.85 (0.71 to 1.00)−15.20.15
 150–225 min/week226 (201 to 254)203 (175 to 234)630.90 (0.80 to 1.02)−9.70.36
 >225 min/week223 (190 to 261)230 (197 to 269)420.99 (0.85 to 1.15)−1.50.84
  • *Adherence was calculated as the mean minutes of exercise per week for the exercise group over the 52 weeks of the study.

  • †Blood samples from n=159 participants in the control group and n=156 participants in the exercise group were obtained. A further n=1, 12 and 3 participants were removed from the SOD, 8-iso-PGF2α and 8-OHdG analyses, respectively, as they were outliers or below the limit of detection.

  • ‡Ratio of geometric means at 12 months to geometric means at baseline, adjusted for the baseline oxidative stress biomarker or antioxidant activity level and age.

  • §Percentage change in adherence group mean of each oxidative stress biomarker or antioxidant activity level at 12 months from baseline, adjusted for the baseline oxidative stress biomarker or antioxidant activity level and age.

  • ¶p Value tests difference in changes in oxidative stress biomarker or antioxidant activity biomarker levels between the control group and the specified adherence group, adjusted for the baseline value of the oxidative stress biomarker or antioxidant activity level and age. A unified model, where the adherence group was treated as a categorical variable, was used to calculate the p values, which correspond to β-coefficients for the other quintile groups, using the control group as the referent group.

  • **p Value for trend represents a test of linear association between the adherence quintile and change in oxidative stress biomarker or antioxidant activity level from baseline to 12 months. This test is based on a linear model predicting change at 12 months from baseline, with predictors: baseline oxidative stress biomarker or antioxidant activity level, age and adherence quintile, where quintiles are numbered 1–5 and these values are treated as a continuous variable.

  • 8-iso-PGF2α, 8-isoprostaglandin F2α; 8-OHdg, 8-hydroxy-2′-deoxyguanosine; CAT, catalase; SOD, superoxide dismutase.