2. Increased Arterial Stiffness Following Acute Resistance Exercise is Associated with Changes in Autonomic Tone

Abstract

Background

Although acute and chronic resistance exercise is associated with increases in arterial stiffness, the underlying mechanisms are not completely understood. Autonomic nervous system function is associated with arterial stiffness. Therefore, the purpose of this study was to test the hypothesis that acute resistance exercise would increase arterial stiffness and this increased arterial stiffness would be related to changes in autonomic nervous system function.

Methods

Using a randomized cross over design, 14 healthy young subjects (age 20.8 ± 2.2 yrs, BMI 23.4 ± 1.9) completed a resistance exercise session and a sham control session (seated rest in the exercise room) on two separate days. Carotid-femoral pulse wave velocity (PWV) and aortic augmentation index (AIx) were used as indices of arterial stiffness. Heart rate variability was used to assess autonomic function. Vascular and autonomic measures were made at baseline and 20 minutes after resistance exercise (8 exercises, 60% of 1 repetition maximal).

Results

There were significant increases in resting heart rate (59.2 ± 2.6 to 80.4 ± 3.1 bpm), aortic systolic blood pressure (96.6 ± 2.4 to 102.4 ± 2.1 mmHg), PWV (6.07 ± 0.3 to 6.36 ± 0.2%), and AIx@75 bpm (-15.3 ± 3.4 to -0.07± 3.3%) (all p<0.05) after resistance exercise compared with sham control. The root-mean square of successive differences (RMSSD), number of RR intervals differing by greater than 50 ms (NN50), and percentage of NN50 (pNN50) as an indices of parasympathetic modulation were significantly decreased after resistance exercise (p < 0.05). Also, changes in PWV after resistance exercise were associated with changes in RMSSD (r=−0.39, p = 0.02) after resistance exercise.

Conclusion

These data indicate that arterial stiffness is increased following acute resistance exercise and changes in arterial stiffness are associated with changes in heart rate variability. This would suggest that increases in arterial stiffness following resistance exercise are associated with changes in autonomic tone.