The effects of isometric exercise training on femoral and brachial artery dimension and blood flow in middle-aged men.

Introduction Previous isometric training studies reporting reductions in resting blood pressure have not explored whether there are concomitant changes in resting artery dimensions and blood flow. Furthermore, the influence of isometric training intensity on these adaptations has not been investigated. Therefore, the purpose of this study was to explore whether training-induced reductions in resting blood pressure are associated with concomitant changes in the vasculature of the trained and untrained limbs and to establish if these adaptations were intensity dependent. Methods Subjects undertook an 8 week training programme consisting of 4x2 min bilateral-leg isometric contractions 3 x per week (Wiles et al., 2010). Two groups exercised at intensities equivalent to 70% (n=10) or 85% (n=10) of their peak heart rate (%HRpeak; as established in a prior incremental test), and a third group acted as controls (n=10). Resting systolic (SBP), mean arterial (MAP) and diastolic (DBP) blood pressure was measured at baseline and post-training. Artery diameter and mean blood flow (brachial and femoral) were also measured at rest using Doppler ultrasound. Analysis of variance was used to determine whether post-training measures were significantly different to baseline. Also, baseline values were used as a covariate to account for initial resting blood pressure values. Results There were significant reductions in resting SBP (-10.8±7.9 mmHg) and MAP (-4.7±6.8 mmHg) in the 85%T group post-training and concomitant significant increases in resting femoral mean artery diameter (FMAD; 1.0±0.4 mm) and femoral mean blood velocity (FMBV; 0.68±0.83 cm/s), which resulted in increased femoral artery blood flow (FABF; 82.06±31.92 ml/min). There were no significant changes in brachial artery measures after training. Furthermore, there were no significant changes in any resting measure in the 70%T or control group. Discussion This study shows that the reductions in resting SBP and MAP observed after isometric training are associated with concomitant increases in resting artery dimensions and blood flow, but these changes were restricted to the trained limbs. This suggests that the vascular adaptations were localised. Furthermore, these adaptations seem to be training-intensity dependent, as they were not observed in the 70%T training group. These findings could be explained by reduced resting vascular tone, enhanced endothelium-dependent function or by vascular remodelling. The stimulus for such adaptations may arise from changes in availability/activity of nitric oxide as a result of sheer stresses during isometric exercise (McGowan et al. 2007). Exactly how these sheer stresses occur during isometric exercise and how they might be related to isometric training intensity would be deserving of future study. McGowan CL, Levy AS, McCartney N, MacDonald MJ. (2007). Clin. Sci. 112, 403-409. Wiles JD, Coleman DA, Swaine IL. (2010). Eur. J. Appl. Physiol. 108, 419-428

The Effects of Training Involving Simultaneous Walking with Isometric Exercise on Resting Blood Pressure in Young Healthy Adults

Introduction In separate studies, walking and isometric training have been shown to reduce resting blood pressure. Combined aerobic and resistance training, where participants undertake one element of the training programme followed by the second has been seen to produce larger reductions in resting blood pressure (BP) compared to a single exercise protocol such as, walking (Calders et al. 2010). To date, no studies have investigated the effects of simultaneous, combined training on resting BP. Therefore, this study aims to determine the effect of 6-weeks simultaneous, combined isometric (handgrip) and walking training (HGW) on resting systolic (SBP) and diastolic blood pressure (DBP), compared to a walking training programme (WLK). Methods A total of 26 healthy sedentary participants (male, n = 16; female, n = 10; age 21.3±2yrs; mass 69.2±12.5kg; height 170.4±9cm) were randomly allocated, into three groups walking training (WLK; n=12), simultaneous walking and handgrip training (HGW; n=12) or controls. Resting SBP, DBP and mean arterial blood pressure (MAP) were measured at baseline and post-training. Analysis of covariance was used to determine if post-training measures were significantly different to baseline, using the baseline values as the covariate. Results The preliminary data show that, in the three groups, resting SBP was reduced after the 6-weeks, by -12.3, -6.7 and -0.4 mmHg, for HGW, WLK and CON groups respectively. DBP was reduced by -6.4, -3.3 and -0.2 mmHg and MAP by -3.3, -2.2 and -0.2 mmHg. Whilst all changes in the HGW and WLK groups were significant (P<0.05), there were no significant changes in any of the resting blood pressure measured in the control group. Discussion The results indicate that combining walking with simultaneous handgrip isometric exercise, caused greater reductions in resting SBP, DBP and MAP, than walking only. The magnitude of the changes in the HGW group are substantially greater than those observed in previous walking only studies (7.4-1.9 mmHg; Murphy et al. 2007) despite a considerably shorter training intervention. The reductions are also greater than many of the previous studies involving handgrip only training in normotensive participants (McGowan et al. 2007). These sizeable reductions in resting BP emphasise the antihypertensive potential of simultaneous combined exercise training especially since they are evident even in individuals whose BP is considered to be in the normal range. Calders P, Elmahgoub S, Roman de Mettelinge T, Vanderbroeck C, Dewandele I Rombaut L, Vandevelde A, Cambier D. (2011). Clin. Rhab. 25, 1097-1108. McGowan CL, Levy AS, McCartney N, MacDonald MJ. (2007). Clin. Sci. 112, 403-409. Murphy MH, Nevill AM, Murtagh EM, Holder RL. (2007). Preventive Med. 44, 377-385

Responses to an isometric leg-exercise test predicts sex-specific training-induced reductions in resting blood pressure after isometric leg training

Isometric training, using either isometric handgrip (IHG) or isometric bilateral-leg (IBL) protocols, is an effective method of lowering resting systolic blood pressure (SBPrest). However, the reductions in SBPrest seen after training vary widely between individuals. Predicting likely training-induced reductions in SBPrest could make it possible to optimise the effects of the training in all participants. It is known that post-IHG training reductions in SBPrest can be predicted by SBP responses to a 2 minute IHG task in both hypertensive and older normotensives (Millar et al., 2009; Badrov et al., 2013). However, the predictability of such a test in younger individuals and when using a comparable IBL task, has not been established. Furthermore, it is not known whether these simple isometric tests can predict reductions in ambulatory SBP (mean 24-hour, SBPamb) as well as SBPrest. Therefore, the purpose of this study was to determine whether an IBL test can be used to predict training-induced reductions in SBPrest and SBPamb following 10 weeks of IBL training in young men and women.Resting and ambulatory BP (SBPrest and SBPamb) were measured prior to and following 10 weeks of IBL training using an isokinetic dynamometer (4, 2-minute contractions at 20% MVC with 2 minute rest periods, 3/week) in 20 normotensive individuals (10 men, age=21 ± 4 years; 10 women, age=23 ± 5 years). SBP responses to the IBL test (single 2-minute period of IBL exercise) was derived by calculating the difference between peak SBP and mean baseline SBPrest. Pearson’s product moment correlation coefficient was used to assess the relationship between the blood pressure responses to a short 2-minute IBL test and the magnitude of the reductions in SBPrest and SBPamb after IBL training.ResultsThere were significant reductions in men and women’s SBPrest (7.4±5.1mmHg, p=0.0001 & 5.7±4.1mmHg, p=0.001) and SBPamb (4.0±1.9mmHg, p=0.011 & 6.1±5.8mmHg, p=0.0001) following training. These changes in SBPrest were strongly correlated with pre-training SBP response to the IBL test in both men (r=-0.83, p=0.003, SEE=3.03) and women (r = -0.81, p=0.004, SEE=2.56). However, the magnitude of the reductions in SBPamb were not correlated with SBP response to the IBL test (men, r=-0.44, p=0.199, SEE=1.76; women, r=-0.23, p=0.517, SEE=6.01).These results support previous research which has identified that IBL training is an effective tool for lowering both resting and ambulatory BP. Furthermore, a simple isometric exercise test can be used as a tool to predict reductions in resting SBP, but not ambulatory SBP, after IBL training in both men and women. This test could be used to optimise the effects of this type of training in a wider range of participants, perhaps through modification of the training, to suit the anticipated effects in different individuals

Reductions in resting blood pressure in young adults when isometric exercise is performed whilst walking

Aerobic and isometric training have been shown to reduce resting blood pressure, but simultaneous aerobic and isometric training have not been studied. The purpose of this study was to compare the changes in resting systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP) after 6 weeks of either (i) simultaneous walking and isometric handgrip exercise (WHG), (ii) walking (WLK), (iii) isometric handgrip exercise (IHG), or control (CON). Forty-eight healthy sedentary participants (age 20.7 ± 1.7 yrs, mass 67.2 ± 10.2 kg, height 176.7 ± 1.2 cm, male , and female ) were randomly allocated, to one of four groups ( in each). Training was performed 4 × week−1 and involved either treadmill walking for 30 minutes (WLK), handgrip exercise 3 × 10 s at 20% MVC (IHG), or both performed simultaneously (WHG). Resting SBP, DBP, and MAP were recorded at rest, before and after the 6-week study period. Reductions in resting blood pressure were significantly greater in the simultaneous walking and handgrip group than any other group. These results show that simultaneous walking and handgrip training may have summative effects on reductions in resting blood pressure

Establishing Equivalent Training Intensities for Isometric Bilateral-Leg and Handgrip Exercise Using the Category Ratio Scale

Isometric handgrip (IHG) training is commonly undertaken at an exercise intensity of 30% of a subject’s maximum voluntary contraction (MVC) (McGowan et al., 2007). Matching this intensity with isometric bilateral-leg (IBL) exercise is difficult due to the different muscle mass involved. Comparative studies (Howden et al., 2002) have tended to use different exercise intensities without providing a strong rationale. Therefore, the purpose of this study was to use the Category Ratio Scale (CR-10) to establish equivalent exercise intensities for IHG and IBL, based on participant effort perception and to test the extent to which intensity can be matched, when using this method during training sessions. A total of 26 healthy participants (male, n = 18; female, n = 8) undertook two minutes of unilateral IHG to establish the mean CR-10 values. Then, performed IBL exercise at 15, 20 and 25%MVC. The IBL intensity at which CR-10 most-closely matched the values for IHG, was identified as 20%MVC. Subsequently, an IHG and IBL training session was used, to test the extent to which the intensities were matched, according to effort perception. Ten participants (male, n = 6; female, n = 4) undertook 4 x 2 minutes unilateral IHG (30%MVC) and IBL (20%MVC) training, with 2 minutes recovery between contractions with CR-10 measured at the end of each exercise bout. A one-way independent ANOVA was used to identify the IHG and IBL intensities that were most-closely matched. To determine whether CR-10 values were significantly different during the IHG and IBL training sessions, a two-way mixed-model ANOVA was used.The intensity at which CR-10 was most-closely matched between IHG and IBL was 20%MVC. There were significant differences in the CR-10 values between IHG contractions at 30%MVC and IBL at 25%MVC and 15%MVC (P > 0.05) but not at 20%MVC (P 0.05).These results suggest when performing IBL exercise, the intensity most closely matching the IHG intensity (30%MVC) is 20%MVC. Furthermore, it can be seen from the simulated training sessions that CR-10 does not significantly differ between the two intensities until the final 2-minute bout. Therefore, it may be advantageous when undertaking one-off IBL exercise or IBL training protocols with the purpose of comparing data to that from IHG, to use 20%MVC. However, when a 4 x 2 minute training protocol is used, it may be necessary to attenuate the intensity of the 4th bout of IBL

The Mechanism Underlying the Hypotensive Effect of Isometric Handgrip Training: Is it Cardiac Output Mediated?

Isometric handgrip (IHG) training lowers blood pressure (BP) in normotensive individuals yet the mechanisms remain equivocal, and some evidence suggests that men and women respond differently to training. To date, non-sex specific mechanisms influencing total peripheral resistance, either in response to a single IHG bout or with training, have been a primary research focus, and the effects of acute and chronic IHG on cardiac output (Q) in either sex are under-explored. The purpose of the current study was two-fold: 1) to investigate the effects of IHG training (4, 2-minute sustained bilateral isometric contractions at 30% of maximal contraction, 1-minute rest between, 3X/week for 10 weeks) on resting Q, and 2) to examine the Q response to an IHG bout, and the effects of training on this response. Resting BP (Dinamap Carescape v100, Critikon) was measured after 10 minutes of seated rest in twenty-two normotensive participants (10 women; mean age= 24 ± 5.0 years). To assess Q, aortic root diameter (ARD; 3S-RS probe; Vivid I, GE Healthcare), velocity-timed integral (VTI; P2D probe; Vivid I), and HR (Dinamap) were measured pre- and post- an IHG bout. Both variables were re-assessed post-training. Reductions in resting systolic BP of a similar magnitude (p>0.05) were observed in both men (2.4 ± 6.2 mmHg) and women (2.9 ± 4.6 mmHg) following 10 weeks of training (p=0.04). This was accompanied by reductions in resting Q (p=0.007) in both men (6.6 ± 2.2 to 6.3 ± 1.8 L/min) and women (5.8 ± 0.7 to 5.1 ± 0.8 L/min) and reductions in HR (p=0.036), both of which were similar between sexes (all p>0.05). In both groups, no changes in Q were observed in response to an IHG bout, and this response was similar pre- and post- training (all p>0.05). In conclusion, resting Q is reduced with training, potentially implicating it as a mechanism of post-training BP reductions. The acute response to an IHG bout remains unchanged with training

Validity of a pictorial perceived exertion scale for effort estimation and effort production during stepping exercise in adolescent children

This is the author's PDF version of an article published in European Physical Education Review ©2002. The definitive version is available at http://epe.sagepub.com.Recent developments in the study of paediatric effort perception have continued to emphasise the importance of child-specific rating scales. The purpose of this study was to examine the validity of an illustrated 1 – 10 perceived exertion scale; the Pictorial Children’s Effort Rating Table (PCERT). 4 class groups comprising 104 children; 27 boys and 29 girls, aged 12.1±0.3 years and 26 boys, 22 girls, aged 15.3±0.2 years were selected from two schools and participated in the initial development of the PCERT. Subsequently, 48 of these children, 12 boys and 12 girls from each age group were randomly selected to participate in the PCERT validation study. Exercise trials were divided into 2 phases and took place 7 to 10 days apart. During phase 1, children completed 5 x 3-minute incremental stepping exercise bouts interspersed with 2-minute recovery periods. Heart rate (HR) and ratings of exertion were recorded during the final 15 s of each exercise bout. In phase 2 the children were asked to regulate their exercising effort during 4 x 4-minute bouts of stepping so that it matched randomly prescribed PCERT levels (3, 5, 7 and 9). Analysis of data from Phase 1 yielded significant (P<0.01) relationships between perceived and objective (HR) effort measures for girls. In addition, the main effects of exercise intensity on perceived exertion and HR were significant (P<0.01); perceived exertion increased as exercise intensity increased and this was reflected in simultaneous significant rises in HR. During phase 2, HR and estimated power output (POapprox) produced at each of the four prescribed effort levels were significantly different (P<0.01). The children in this study were able to discriminate between 4 different exercise intensities and regulate their exercise intensity according to 4 prescribed levels of perceived exertion. In seeking to contribute towards children’s recommended physical activity levels and helping them understand how to self-regulate their activity, the application of the PCERT within the context of physical education is a desirable direction for future research

Effects of Isometric Resistance Training and a Maintenance Dose on Ambulatory Blood Pressure and Morning Blood Pressure Surge in Young Normotensives

Introduction Hypertension, a modifiable risk factor for cardiovascular disease (CVD) is associated with approximately one third of deaths globally each year. Diurnal blood pressure (BP) variability and more specifically morning blood pressure surge (MBPS) are associated with increased risk of stroke, end-organ damage and are considered to be destabilising factors for atherosclerotic plaques. Isometric resistance training (IRT) has been shown to reduce ambulatory BP and MBPS following 8-10 weeks of training. However, there is no data at present which has established the dose of training needed to maintain these reported reductions following the initial IRT period. Therefore, the purpose of this study was to determine the effects of IRT on ambulatory BP and the MBPS in young normotensives following (i) 8 weeks of IRT and (ii) 8 weeks of a once a week maintenance dose. Methods Twenty-five normotensive individuals (15 men, age=21±4 years; 10 women, age=22±3 years) were randomly assigned to a training-maintenance (TRA-MT, n=13) or control (CON, n=12) group. Ambulatory BP and MBPS were measured prior to, after an 8-week (3 days/week) training period and following an 8-week maintenance period (1 day/week) of bilateral leg IRT using an isokinetic dynamometer (4 x 2-minute contractions at 20% MVC with 2-minute rest periods). A two-way repeated measures MANOVA was used to assess the within and between groups changes in ambulatory BP and MBPS. MBPS was calculated as: mean systolic BP 2 hours after waking, minus the lowest sleeping 1-hour mean systolic BP. Results There were significant reductions in 24-h ambulatory systolic BP following IRT (pre-to-post training, -7±5 mmHg, p=0.001) and these reductions remained after the maintenance period (pre-to-post maintenance, -6±4 mmHg, p=0.000). There were significant reductions in daytime BP (pre-to-post training, -5±5 mmHg, p=0.034) which remained following maintenance (pre-to-post maintenance, -5±5 mmHg, p=0.02), but there was no change in night-time systolic BP (pre-to-post training, -2±5 mmHg, p=0.685) or post maintenance period (pre-to-post maintenance, 1±6 mmHg, p=0.94). Additionally, there were significant reductions in the MBPS (pre-to-post training, -9±10 mmHg, p=0.005) which were maintained post maintenance period (pre-to-post maintenance, -8±11 mmHg, p=0.014). Additionally, significant correlation was identified between the magnitude of the change in MBPS and the magnitude of changes in mean SBP 2-h after waking (r = 0.78, P=0.002). Discussion These results provide further evidence that IRT causes significant reductions in MBPS in addition to the previously reported reductions in ambulatory BP. Additionally, these reductions seem to be maintained with a reduced exercise dose. These findings may also have important clinical implications, the significant reductions in the MBPS offer the potential for meaningful CVD and stroke risk reduction, provided these effects can be demonstrated in those who are at risk

Intensity-dependent reductions in resting blood pressure following short-term isometric exercise training

To reduce resting blood pressure, a minimum isometric exercise training (IET) intensity has been suggested, but this is not known for short-term IET programmes. We therefore compared the effects of moderate- and low-intensity IET programmes on resting blood pressure. Forty normotensive participants (22.3 ± 3.4 years; 69.5 ± 15.5 kg; 170.2 ± 8.7 cm) were randomly assigned to groups of differing training intensities [20%EMGpeak (~23%MVC, maximum voluntary contraction, or 30%EMGpeak (~34%MVC)] or control group; 3 weeks of IET at 30%EMGpeak resulted in significant reductions in resting mean arterial pressure (e.g. −3.9 ± 1.0 mmHg, P 0.05). Moreover, after pooling all female versus male participants, IET induced a 6.9-mmHg reduction in systolic blood pressure in female participants, but only a 1.5-mmHg reduction in systolic blood pressure in male participants, although the difference was not significant. An IET intensity between 20%EMGpeak and 30%EMGpeak is sufficient to elicit significant resting blood pressure reductions in a short-term training period (3 weeks). In addition, sexual dimorphism may exist in the magnitude of reductions, but further work is required to confirm this possibility, which could be important in understanding the mechanisms responsible

Using Bilateral and Unilateral Exercise to Better Understand the Blood Pressure Lowering Effects of Isometric Handgrip Training: Preliminary Findings

Isometric handgrip (IHG) training reduces resting blood pressure (BP) in normotensive individuals following 8-10 weeks of unilateral (4 x 2 minute sustained contractions at 30% maximal voluntary contraction (MVC) performed by the non-dominant limb, separated by 4 minutes rest) or bilateral IHG training (contractions alternating between dominant and non-dominant limb, separated by 1 minute rest), performed 3-5 times per week. Investigating the effects of a single bout of unilateral or bilateral IHG on vascular function (brachial artery flow-mediated dilation (FMD) and low-flow mediated constriction (L-FMC)) may provide insight into the underlying hypotensive mechanisms of IHG training. Eight young adult (25.3 ± 3.81 years), normotensive (99.65/61.25 ± 11.72/9.14 mmHg) women performed a single bout of bilateral (n=4) or unilateral (n=4) IHG exercise. FMD and L-FMC were assessed using ultrasound pre- and post-IHG bout. Following a single IHG bout, no significant changes were observed in FMD (unilateral: pre- = 13.56 ± 7.8%, post- =17.26 ± 21%, bilateral: pre- = 17.11 ± 1.1%, post- = 21.18 ± 8.9%) or L-FMC (unilateral: pre- = 3.36 ± 11%, post- =-2.26 ± 16%, bilateral: pre- = -2.86 ± 3.1%, post- = -1.94 ± 9.7%) in either group (all p > 0.05). Taken together these preliminary data suggest that in young healthy women, irrespective of isometric exercise on 1 or 2 limbs, the endothelium is not altered significantly. Further research with a larger sample is warranted to confirm that mechanisms other than improved vascular function play a role in IHG-training induced BP lowering