During 508,332 person years of follow-up (18 years), we documented 2,278 new cases of T2DM. shows the baseline characteristics of the study population by levels of weight training per week. Fourteen percent of men reported weight training at baseline. Whereas the age adjusted percentage that engaged in weight training increased with time to 29% in 2006, the average time spent weight training among these individuals appeared stable over time (). Men who reported weight training ≥150 min/week at baseline performed more aerobic exercise, viewed less TV, drank less alcohol, were less likely to smoke, and had a healthier dietary intake profile (except for glycemic load) compared to men reporting no weight training.
Age-adjusted baseline (1990) characteristics of the study population by levels of weight training per week.
Participation in weight training over time (1990 – 2006)
shows the association of weight training and aerobic exercise with the risk of T2DM. In multivariable adjusted analysis including aerobic exercise men performing weight training 1–59, 60–149, and ≥150 min/week had RRs of 0.88, 0,75, and 0.66 lower risk of T2DM (p<0.001 for trend), respectively, compared to men reporting no weight training. The RR for T2DM for men performing 1–59, 60–149, and ≥150 min/week of aerobic exercise respectively compared to men reporting no aerobic exercise was 0.93, 0.69, and 0.48 (p<0.001 for trend) in multivariable adjusted analysis. When using the baseline information only or the simple updated information on weight training (instead of the cumulatively updated) results modestly attenuated (baseline: multivariable adjusted RR=0.67 (95%CI 0.51–0.88), simple updated: multivariable adjusted RR=0.75 (95%CI 0.60–0.94) for the highest categories of weight training). Using a 4 year lag in exposure classification strengthened the association (multivariable adjusted RR=0.50 (95%CI 0.33–0.76) for the highest category of weight training). To assess the possibility of residual confounding, we included covariates as continuous variables where possible, but this did not materially change the results. To further address the possibility that the association of weight training with risk of T2DM was due to confounding by aerobic exercise, we restricted the analysis to men who reported no aerobic exercise. This analysis showed that any weight training was associated with 48% (95% CI 1–72) lower risk compared to no weight training in multivariable adjusted analysis. In a secondary analysis, we also analyzed if weight training was associated with mortality from CVD (n=1,901 deaths) and all-causes (n=6,251 deaths). The age-adjusted RRs across categories of weight training were 0.76, 0.79, and 0.78 (p=0.009 for trend) for CVD mortality and 0.75, 0.82, and 0.89 (p=0.002 for trend) for all-cause mortality. After multivariable adjustment including aerobic exercise, the corresponding RRs were 0.90, 1.00, and 0.98 (p=0.82 for trend) for CVD mortality and 0.88, 1.04, and 1.11 (p=0.38 for trend) for all-cause mortality. Treating death from all causes as a competing risk gave similar results to the standard cox model in the analysis with T2DM as outcome.
Weight training, aerobic exercise and risk of type 2 diabetes in men from Health Professional Follow-up Study (1990–2008).
Adjusting for BMI moderately attenuated the associations for both weight training (multivariable adjusted RR=0.71 (95%CI 0.49–1.00) for the highest category) and aerobic exercise (multivariable adjusted RR=0.61 (95%CI 0.53–0.70) for the highest category) with T2DM risk. A sub-sample of the participants also had information on waist circumference in 1987 and 1996 (total of 413,890 person-years and 1,850 cases). Using this to assess mediation by adiposity attenuated the association of weight training and aerobic exercise to a larger extent (weight training RR=0.76 (95%CI 0.51–1.14) and aerobic exercise RR=0.62 (95%CI 0.53–0.73) for the highest categories, although the trend across categories were still present for both exercise types (p<0.05 for trend).
Results from the multivariable adjusted restricted cubic spline regression showed that the risk of T2DM decreased linearly with increasing time spent weight training (p=0.59 for non-linear response) (). For each 60 min of weight training per week the risk of T2DM decreased by 13 percent (95%CI 6 – 19, p<0.001). For aerobic exercise the relationship clearly appeared non-linear with the strongest association at the lower level of aerobic exercise (p<0.001 for non-linear response) (eFigure
Dose response relationship between weight training (min/week) and risk of type 2 diabetes
We then examined the association of weight training and aerobic exercise stratified by age (<65, ≥65 years), BMI (<30, ≥30 kg/m2
), family history of T2DM (yes, no), and dietary index score (below and above the median) ( and eTable
). The association of weight training with T2DM were stronger among men below 65 years of age (p<0.001 for multiplicative interaction). There was also evidence that the association was stronger among men with no family history of T2DM (p=0.04 for multiplicative interaction). This was less apparent for aerobic exercise where associations were fairly similar across these strata (eTable
Weight training and risk of type 2 diabetes in men from Health Professional Follow-up Study (1990–2008) stratified by age, body mass index, family history of type 2 diabetes, and dietary index score.
Finally we examined the joint association of weight training and aerobic exercise with the risk of T2DM (). Men who adhered to the current recommendations on aerobic exercise (at least 150 min/week) and engaged in weight training of at least 150 min/week had the greatest reduction in T2DM risk (RR=0.41, 95%CI 0.27–0.61), p=0.26 for multiplicative interaction.
Joint association of weight training and aerobic exercise with the risk of type 2 diabetes