Ultrafast Ultrasound-Derived Muscle Strain Measure Correlates with Carotid Local Pulse Wave Velocity in Habitual Resistance-Trained Individuals

Hsin-Fu Lin,Yi-Hung Liao,Pai-Chi Li

doi:10.3390/app11188783

Abstract

Purpose: this study investigated the effects of the intensity of machine-based bicep curl resistance exercise on ultrafast ultrasound-derived muscle strain rate and carotid ultrafast pulse wave velocity (ufPWV), and examined the association between muscle strain rate, ufPWV, and established carotid function measures in habitual resistance-trained individuals. Methods: twenty-three young habitual resistance-trained males (age: 24 ± 1 year, body mass index = 24 ± 1 kg/m2) were recruited to participate in two bouts of acute bicep curl exercise. After one-repetition maximum determination (1RM), the participants were randomly assigned to engage in bicep curls at 40 or 80%1RM intensity (10 reps × five sets) by a crossover study design. The muscle strain rate of bicep muscle, carotid ufPWV during systole(ufPWV-sys), and diastole (ufPWV-dia) were obtained pre- and post-exercise. In addition, carotid function measures were calculated by obtained carotid diameter and central blood pressure changes. Results: compared with pre-exercise, the reduction in post-exercise muscle strain rate and its area under the curve of 80%1RM was greater than those of 40%1RM. Both ufPWV-sys and ufPWV-dia increased regardless of exercise intensity. Baseline bicep muscle strain rate correlated not only with ufPWV-sys (r = −0.71, p = 0.001), ufPWV-dia (r = −0.74, p = 0.001), but also carotid compliance (r = 0.49, p = 0.02), distensibility (r = 0.54, p = 0.01) and ß stiffness (r= −0.84, p < 0.0001). The ufPWVs also correlated with ß stiffness (r = 0.64–0.76, p = 0.01). Conclusion: muscle stiffness measured by ultrafast ultrasound elastography increases positively with resistance exercise intensity, and it appears to correlate with carotid ufPWV and established carotid function measures in habitual resistance-trained individuals.

Highlights

Habitual resistance exercise has been shown to improve muscular fitness and health benefits through physiological adaptations such as muscle hypertrophy and enhanced muscle strength after training [1]; high-intensity resistance exercise has been shown to acutely [2] and chronically [3] result in impaired central arterial function in young adults.Greater sympathetic and fluctuation of arterial pressure resulting from intensive training are potential underlying mechanisms that affect central arterial stiffness [4]
We examined the relationships among muscle strain rate, ultrafast pulse wave velocity (uf pulse wave velocity (PWV)) indices and established local carotid function measures in this population
Habitual high-intensity resistance exercise training has been demonstrated to reduce central arterial compliance [2,3,36] compared with the sedentary control; the higher uf PWV-dia in the present study indicates greater diastolic arterial stiffness in this population, which supports these previous findings

Summary

Introduction

Habitual resistance exercise has been shown to improve muscular fitness and health benefits through physiological adaptations such as muscle hypertrophy and enhanced muscle strength after training [1]; high-intensity resistance exercise has been shown to acutely [2] and chronically [3] result in impaired central arterial function in young adults.Greater sympathetic and fluctuation of arterial pressure resulting from intensive training are potential underlying mechanisms that affect central arterial stiffness [4]. Ultrasound strain elastography is one of the methods in quantitating muscular stiffness based on the principle of tissue deformation in response to the amount of applied stress; softer tissue experiences larger strain than stiffer tissue [9]. Gao et al (2016) demonstrated that stiffness could be measured when applying an external force on muscle tissue by quantitating the changed length from the original muscle length. This method can effectively present the anatomical properties of the muscles [11]. Dankel and Razzano [12] summarized that acute but not regular resistance exercise increases muscle stiffness monitored by using ultrasound imaging; the extent to which how resistance exercise variables (i.e., intensity, duration, volume) would affect muscle stiffness is less characterized due to limited research evidence in this research topic

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