Blood pressure-lowering efficacy of a 6-week multi-modal isometric exercise intervention.

Isometric exercise training (IET) is an effective method for reducing resting blood pressure (BP). To date, no research studies have been conducted using multiple exercises within an IET intervention. Previous research has suggested that varied exercise programmes may have a positive effect on adherence. Therefore, this randomized controlled study aimed to investigate the BP-lowering efficacy of a multi-modal IET (MIET) intervention in healthy young adults. Twenty healthy participants were randomized to an MIET [n = 10; four women; SBP 117.9 ± 6.9 mmHg; DBP 66.3 ± 5.1 mmHg] or control (CON) group (n = 10; five women; SBP, 123.3 ± 10.4 mmHg; DBP, 77.3 ± 6.7 mmHg). The MIET group completed three sessions per week of 4, 2-min isometric contractions, with a 1-min rest between each contraction, for 6 weeks. Resting BP and heart rate (HR) were measured at baseline and post-intervention. Pre-to-post intervention within-group reductions in resting BP were observed (SBP: 5.3 ± 6.1 mmHg, DBP: 3.4 ± 3.7 mmHg, MAP: 4.0 ± 3.9 mmHg, HR: 4.8 ±6 .6 bpm), although clinically relevant (≥2 mmHg), these changes were not statistically significant. Significant (p < 0.05) between-group differences were found between the intervention and control groups, indicating that the MIET intervention has a greater BP-lowering effect compared to control. The clinically relevant post-training reductions in resting BP suggest that MIET may be a promising additional IET method for hypertension prevention. These findings; however, must be interpreted with caution due to the small sample size and the non-clinical cohort.

The influence of crank configuration on muscle activity and torque production during arm crank ergometry.

This study investigated the effect of crank configuration on muscle activity and torque production during submaximal arm crank ergometry. Thirteen non-specifically trained male participants volunteered. During the research trials they completed a warm-up at 15W before two 3-min exercise stages were completed at 50 and 100W; subjects used either a synchronous or asynchronous pattern of cranking. During the final 30-s of each submaximal exercise stage electromyographic and torque production data were collected. After the data had been processed each parameter was analysed using separate 2-way ANOVA tests with repeated measures. The activity of all muscles increased in line with external workload, although a shift in the temporal pattern of muscle activity was noted between crank configurations. Patterns of torque production during asynchronous and synchronous cranking were distinct. Furthermore, peak, minimum and delta (peak-minimum) torque values were different (P<0.05) between crank configurations at both workloads. For example, at 100W, peak torque using synchronous [19.6 (4.3) Nm] cranking was higher (P<0.05) compared to asynchronous [16.8 (1.6) Nm] cranking. In contrast minimum torque was lower (P<0.05) at 100 W using synchronous [4.8 (1.7)Nm] compared to asynchronous [7.3 (1.2)Nm] cranking. There was a distinct bilateral asymmetry in torque production during asynchronous cranking with the dominant transmitting significantly more force to the crank arm. Taken together, these preliminary data demonstrate the complex nature of muscle activity during arm crank ergometry performed with an asynchronous or synchronous crank set-up. Further work is required to determine how muscle activity (EMG activity) and associated patterns of torque production influence physiological responses and functional capacity during arm crank ergometry.