The main finding of this study is that both exercise programs (i.e., aerobic and strength-based) resulted in positive changes in important cardiovascular risk factors, namely TC, TG, LDL-C, HDL-C, TC/HDL-C, hs-CRP, DBP, BMI, WC, and BW, in a previously sedentary group of older women and men. Moreover, cardiorespiratory fitness also improves as result of the increase on the 6-minute walk distance. Dietary composition is a potentially confounding factor and is known to influence lipoprotein concentrations. To minimize any confounding effects associated with variation in diet, all participants were fed a similar diet during the 16 weeks of the investigation. Both programs were successfully in that they both resulted in 13% gains on 6-min walk distance. This observation suggests that aerobic and strength based exercise programs may result in improved cardiovascular functionality in older participants, potentially countering the documented age-related decline in peak oxygen uptake.
Following studies examining the effects of endurance and strength training on cardiovascular health have generally found either positive changes in lipid profile or no changes at all. More favorable changes in response to training occur usually in those with more pronounced dyslipidemia at baseline , and have been pointed as dependent on loss of body fat . Our baseline values were normal for TG and HDL-C, optimal for LDL-C, and desirable (control group) and borderline high (exercising group) for TC, according to the guidelines . Also, in the current study, at baseline in the total participant group, BMI, WC and BW correlated positively with TC, TG and hs-CRP. Moreover, WC and BW correlated with TC/HDL-C.
Our finding that TC, LDL-C, TG, and TC/HDL-C diminish with exercise is consistent with previous research [12, 13], even those programs that have not attained resulted in gains after strength training in postmenopausal women  and in adult men . To explain why some programs have not resulted in gains, some researchers have pointed a dose-response relationship between serum lipid levels (TC, TG, HDL-C, and TC/HDL-C) and levels of physical activity (intensity and duration) in adult women and men . Accordingly, Cox and colleagues  have demonstrated lower TC and LDL-C after 6 months of higher-, but not lower-, intensity exercise in middle and older sedentary women. However, Sillanpaa and colleagues  failed to attain changes on TC, TG and LDL-C after 21-week of high-intensity endurance and heavy resistance strength training in healthy 40-65-year-old men. Independent of the mechanism underlying lipid changes, a reduction of 1% on TC has been shown to reduce the risk for coronary artery disease by 2% , which implies that our exercising participants have reduced about 12% their risk. Moreover, a 1% reduction in LDL-C reduces the risk of major coronary events by approximately 2% , which means that we have about a 26% gain.
Our finding that HDL-C increases with exercise is consistent with previous results [12, 13, 19]. However, not all studies have found gains in HDL-C following aerobic-based [14–16] or strength-based programs [16–18]. This absence of gains have been justified with the higher initial levels of HDL-C [25, 30], with the lower exercise intensity , with the good initial body composition , and with the lack of control of the time of blood sampling . Seasonal fluctuations  and changes in dietary fat intake or leisure time physical activity may also influence the changes in the lipid profile [34, 35]. Our baseline HDL-C values were within normal range, and both exercising programs seem to have had enough intensity to promote gains on HDL-C, accompanied by reduction on BW, BMI, and WC. Also, a gap of at least 48 hours occurs between the last training session and the sampling. As a decrease of 1% on HDL-C has been associated with a 2-3% increase in the risk for coronary heart disease (CHD) , and assuming that the reverse is true, the 5% increase observed in our both programs should decrease CHD by 10-15%.
Recent data have shown decreases on resting blood pressure after prolonged endurance training of 1.9/1.6 (SBP/DBP) mmHg , and after strength training of about 3 mmHg in both SBP and DBP [38, 39]. This positive effects caused by the physical training have been more pronounced among hypertensive participants . Participants in this study had normal DBP (<80 mm Hg) and high SBP (140-159 mm Hg) at baseline. Interestingly, after the training only DBP have reduced 3 mm Hg that may have clinical and biological relevance in the risk of heart disease.
In this study, aerobic and strength-based training have reduced 26% inflammation as measured by hs-CRP concentrations. Previous findings on the effect of strength and endurance training on hs-CRP levels have been inconsistent, with some studies showing benefits [40, 41] and others showing no effect at all [42, 43]. The mechanisms underlying an exercise training-induced reduction in serum hs-CRP concentrations remain unknown. However, the lack of effects of exercise on hs-CRP has been explained by the few concomitant metabolic risk factors of the participants , and by a lack of changes in anthropometric variables (e.g., body weight, waist circumference) . In fact, our participants at baseline have been sedentary, obese - particularly the exercising group (mean (SD) BMI 30.6 (5.0) kg/m2), and hypertensive (mean (SD) SBP 148 (20) mmHg). Moreover, the changes on BMI, WC and BW could help to justify the changes on hs-CRP. Additionally, the gains on muscular function as result of the increases on 6-minute walk distance would also influence the hs-CRP.
In conclusion, the training programs used in this study produced significant benefits on 6-minute walk distance, DBP, BW, WC, BMI, TG, TC, HDL-C, LDL-C, TC/HDL-C, and hs-CRP. Accordingly, the results of the current study suggest that moderate intensity aerobic-based and strength-based programs, with 16 weeks of duration, are enough to positively influence the metabolic health indicators of sedentary older women and men.