Response to the Editor

Okamoto T , Masuhara M , Ikuta K . Low-Intensity Resistance Training after High-Intensity resistance training can prevent the increase of Central Arterial Stiffness . Int J Sports Med 2013 ; 34 : 385 – 390

Response to A. V. Sardeli’s and A. F. Gáspari’s Letter to the Editor

Dear Editor,

We would like to thank Drs. Amanda Veiga Sardeli and Arthur Fernandes Gáspari for their comments on our article. Differing perspectives are important for the development of future studies. The issue whether resistance training (RT) stiffens arteries has been controversial since the report by Bertovic et al. [1] in 1999 that examined the relationship between RT and arterial elasticity and reported that RT increases arterial stiffness. Many studies have reported that arterial stiffness was significantly increased after high-intensity RT. These results were enhanced by a recent meta-analysis [4], although the findings are not universal [2]. When RT load was increased incrementally, arterial stiffness did not change.

In a previous study [8], we concluded that low-intensity RT following high-intensity RT does not increase central arterial stiffness and might prevent the increase in stiffness induced by high-intensity RT. Our findings might spark some discussion. Although arterial stiffness is not reduced by aerobic exercise before RT, performing aerobic exercise thereafter could reduce arterial stiffness [5]. In addition to this result, our study [8] hypothesized that low-intensity RT after high-intensity RT would reduce arterial stiffness. However, unlike the beneficial effects of aerobic exercise after high-intensity RT, low-intensity RT after high-intensity RT only suppressed increases in arterial stiffness. Therefore, although low-intensity RT after high-intensity RT does not have similar effects as aerobic exercise after high-intensity RT, we considered that the unfavorable effects of high-intensity RT on arterial stiffness are counteracted by subsequent low-intensity RT.

We carefully prescribed exercise protocol in this study. The group that performed low-intensity RT before high-intensity RT completed 2 sets of 10 exercises at 50% of 1RM before 3 sets of 10 exercises at 80% of 1RM. The group that performed low-intensity RT after high-intensity RT completed 2 sets of 10 exercises at 50% of 1RM after 3 sets of 10 exercises at 80% of 1RM. High- and low-intensity RT was conducted with inter-set rest periods of 120 s and 30 s, respectively. The recovery time between training sessions was controlled at 2-min intervals. Our findings suggested that low-intensity RT performed after high-intensity RT suppresses the increase in arterial stiffness. However, arterial stiffness increased when the training schedule was reversed. This slight difference in protocol might therefore be important. Although high-intensity RT increased blood pressure and sympathetic nervous activity, low-intensity RT suppressed such increases [6]. Moreover, while high-intensity RT did not change vascular endothelial function [9], low-intensity RT improved it [7]. Changes in arterial compliance and stiffness are well known to be influenced by both sympathetic nervous activity [3] and vascular endothelial function [10]. Therefore, it is possible to hypothesize that low-intensity RT after high-intensity RT might suppress increases in arterial stiffness through sympathetic nervous activity and vascular endothelial function. However, we could only speculate on the mechanisms responsible for our findings. As you pointed out, there may be other possible causes for our findings.

Future studies will be needed to determine the precise mechanisms underlying the effects of combined high- and low-intensity RT on arterial stiffness.

• References

• 1 Bertovic DA, Waddell TK, Gatzka CD, Cameron JD, Dart AM, Kingwell BA. Muscular strength training is associated with low arterial compliance and high pulse pressure. Hypertension 1999; 33: 1385-1391
• 2 Casey DP, Beck DT, Braith RW. Progressive resistance training without volume increases does not alter arterial stiffness and aortic wave reflection. Exp Biol Med 2007; 232: 1228-1235
• 3 London GM, Guerin AP. Influence of arterial pulse and reflected waves on blood pressure and cardiac function. Am Heart J 1999; 138: 220-224
• 4 Miyachi M. Effects of resistance training on arterial stiffness: a meta-analysis. Br J Sports Med 2013; 47: 393-396
• 5 Okamoto T, Masuhara M, Ikuta K. Combined aerobic and resistance training and vascular function: effect of aerobic exercise before and after resistance training. J Appl Physiol 2007; 103: 1655-1661
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• 8 Okamoto T, Masuhara M, Ikuta K. Low-intensity resistance training after high-intensity resistance training can prevent the increase of central arterial stiffness. Int J Sports Med 2013; 34: 385-390
• 9 Rakobowchuk M, McGowan CL, de Groot PC, Hartman JW, Phillips SM, MacDonald MJ. Endothelial function of young healthy males following whole body resistance training. J Appl Physiol 2005; 98: 2185-2190
• 10 Wilkinson IB, Franklin SS, Cockcroft JR. Nitric oxide and the regulation of large artery stiffness: from physiology to pharmacology. Hypertension 2004; 44: 112-116