Hypertension, or the chronic elevation in resting arterial blood pressure (BP), is a significant risk factor for cardiovascular disease and estimated to affect ~1 billion adults worldwide. The goals of treatment are to lower BP through lifestyle modifications (smoking cessation, weight loss, exercise training, healthy eating and reduced sodium intake), and if not solely effective, the addition of antihypertensive medications. In particular, increased physical exercise and decreased sedentarism are important strategies in the prevention and management of hypertension. Current guidelines recommend both aerobic and dynamic resistance exercise training modalities to reduce BP. Mounting prospective evidence suggests that isometric exercise training in normotensive and hypertensive (medicated and non-medicated) cohorts of young and old participants may produce similar, if not greater, reductions in BP, with meta-analyses reporting mean reductions of between 10 and 13 mmHg systolic, and 6 and 8 mmHg diastolic. Isometric exercise training protocols typically consist of four sets of 2-min handgrip or leg contractions sustained at 20-50 % of maximal voluntary contraction, with each set separated by a rest period of 1-4 min. Training is usually completed three to five times per week for 4-10 weeks. Although the mechanisms responsible for these adaptations remain to be fully clarified, improvements in conduit and resistance vessel endothelium-dependent dilation, oxidative stress, and autonomic regulation of heart rate and BP have been reported. The clinical significance of isometric exercise training, as a time-efficient and effective training modality to reduce BP, warrants further study. This evidence-based review aims to summarize the current state of knowledge regarding the effects of isometric exercise training on resting BP.

There is little published data in relation to the effects of caffeine upon cycling performance, speed and power in trained cyclists, especially during cycling of approximately 60 s duration. To address this, eight trained cyclists performed a 1 km time-trial on an electronically braked cycle ergometer under three conditions: after ingestion of 5 mg x kg-1 caffeine, after ingestion of a placebo, or a control condition. The three time-trials were performed in a randomized order and performance time, mean speed, mean power and peak power were determined. Caffeine ingestion resulted in improved performance time (caffeine vs. placebo vs. control: 71.1 +/- 2.0 vs. 73.4 +/- 2.3 vs. 73.3 +/- 2.7 s; P = 0.02; mean +/- s). This change represented a 3.1% (95% confidence interval: 0.7-5.6) improvement compared with the placebo condition. Mean speed was also higher in the caffeine than placebo and control conditions (caffeine vs. placebo vs. control: 50.7 +/- 1.4 vs. 49.1 +/- 1.5 vs. 49.2 +/- 1.7 km x h-1; P = 0.0005). Mean power increased after caffeine ingestion (caffeine vs. placebo vs. control: 523 +/- 43 vs. 505 +/- 46 vs. 504 +/- 38 W; P = 0.007). Peak power also increased from 864 +/- 107 W (placebo) and 830 +/- 87 W (control) to 940 +/- 83 W after caffeine ingestion (P = 0.027). These results provide support for previous research that found improved performance after caffeine ingestion during short-duration high-intensity exercise. The magnitude of the improvements observed in our study could be due to our use of sport-specific ergometry, a tablet form and trained participants.

No previous studies have examined the effects of isometric training intensity upon resting blood pressure (BP). The aims of this study were (a) to compare the effects of leg isometric training, performed at two intensities, upon resting systolic-SBP, diastolic-DBP and mean arterial-MAP BP; and (b) to examine selected cardiovascular variables, in an attempt to explain any changes in resting BP following training. Thirty-three participants were randomly allocated to either control, high- (HI) or low-intensity (LI) training for 8 weeks. Participants performed 4 x 2 min exercise bouts 3x weekly. Resting BP was measured at baseline, 4-weeks and post-training. SBP, DBP and MAP fell significantly in both groups after training. Changes were -5.2 +/- 4.0, -2.6 +/- 2.9 and -2.5 +/- 2.2 mmHg [HI]; -3.7 +/- 3.7, -2.5 +/- 4.8 and -2.6 +/- 2.5 mmHg [LI] for SBP, DBP and MAP, respectively. There were no significant changes in BP at 4 weeks. No significant changes were observed in any of the other cardiovascular variables examined. These findings suggest that isometric training causes reductions in SBP, DBP and MAP at a range of exercise intensities, when it is performed over 8 weeks. Furthermore, it is possible to reduce resting BP using a much lower isometric exercise intensity than has previously been shown.

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 (PO approx ) 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.

Distance running in humans has been associated with both positive and negative effects on the balance of bone remodelling. There is evidence to suggest that the negative effects may be linked to a failure to balance energy expenditure with an adequate energy intake. Energy restriction is known to reduce the synthesis and serum concentration of insulin-like growth factor 1 (IGF-1), which plays an important role in bone formation. The purpose of the present study was to compare the effects of repeated periods of prolonged treadmill running, under conditions of either energy balance or energy restriction, on markers of bone turnover and serum IGF-1 concentration in trained distance runners. Eight male distance runners [mean age 25.1 (SD 5.9) years, maximal oxygen uptake 61.8 (SD 4.9) ml x kg(-1) x min(-1)] undertook an exercise and diet regime on two separate occasions, 2 weeks apart. On each occasion they performed an intensive, 60 min treadmill run on 3 consecutive days. On one occasion their energy intake was restricted to approximately 50% of their estimated energy requirement (RES), whereas on the other occasion they remained in energy balance (BAL). The N-terminal pro-peptide of type 1 collagen (P1NP), osteocalcin and IGF-1 were measured in serum collected between 0800 and 0900 hours, when fasted and rested, on the day before and the day after each regime. The cross-linked N-telopeptides of type 1 collagen and deoxypyridinoline were measured from 24 h urine collections made on the day before and the final day of each regime and adjusted for creatinine excretion. The results showed that the serum concentration of both P1NP and IGF-1 declined by 15% (P = 0.008) and 17% (P = 0.007) respectively in response to RES, but did not change in response to BAL (P > 0.05). A strong relationship was observed between the magnitude of the reduction in the serum concentration of P1NP and IGF-1 after RES (r = 0.97; P < 0.001). There were no changes in the other bone markers in response to either regime. The results suggested that in trained distance runners, repeated periods of prolonged running do not affect the balance of bone turnover unless energy balance is simultaneously altered. These findings support the link between a negative energy balance, a reduced synthesis or serum level of IGF-1 and reduced collagen synthesis. They may also help to explain the bone remodelling imbalance that has been observed in some male and female distance runners.

Background: Previous meta-analyses based on aggregate group-level data report antihypertensive effects of isometric resistance training (IRT). However, individual participant data meta-analyses provide more robust effect size estimates and permit examination of demographic and clinical variables on IRT effectiveness. Methods: We conducted a systematic search and individual participant data (IPD) analysis, using both a one-step and two-step approach, of controlled trials investigating at least 3 weeks of IRT on resting systolic, diastolic and mean arterial blood pressure. Results: Anonymized individual participant data were provided from 12 studies (14 intervention group comparisons) involving 326 participants (52.7% medicated for hypertension); 191 assigned to IRT and 135 controls, 25.2% of participants had diagnosed coronary artery disease. IRT intensity varied (8–30% MVC) and training duration ranged from 3 to 12 weeks. The IPD (one-step) meta-analysis showed a significant treatment effect for the exercise group participants experiencing a reduction in resting SBP of −6.22 mmHg (95% CI −7.75 to −4.68; P < 0.00001); DBP of −2.78 mmHg (95% CI −3.92 to −1.65; P = 0.002); and mean arterial blood pressure (MAP) of −4.12 mmHg (95% CI −5.39 to −2.85; P < 0.00001). The two-step approach yielded similar results for change in SBP −7.35 mmHg (−8.95 to −5.75; P < 0.00001), DBP MD −3.29 mmHg (95% CI −5.12 to −1.46; P = 0.0004) and MAP MD −4.63 mmHg (95% CI −6.18 to −3.09: P < 0.00001). Sub-analysis revealed that neither clinical, medication, nor demographic participant characteristics, or exercise program features, modified the IRT treatment effect. Conclusion: This individual patient analysis confirms a clinically meaningful and statistically significant effect of IRT on resting SBP, DBP and mean arterial blood pressure.

Isometric exercise training has been shown to reduce resting blood pressure, but the effect that this might have on orthostatic tolerance is poorly understood. Changes in orthostatic tolerance may also be dependent on whether the upper or lower limbs of the body are trained using isometric exercise. Twenty-seven subjects were allocated to either a training or control group. A training group first undertook 5 weeks of isometric exercise training of the legs, and after an 8 week intervening period, a second training group containing six subjects from the initial training group, undertook 5 weeks of isometric arm-training. The control group were asked to continue their normal daily activities throughout the 18 weeks of the study. In all subjects orthostatic tolerance, assessed using lower body negative pressure (LBNP), and resting blood pressure were measured before and after each of the 5 week training or control periods. Estimated lean leg volume was determined before and after leg-training. During all LBNP tests, heart rate and blood pressure were recorded each minute, and the time taken to reach the highest heart rate was derived (time to peak HR). Resting systolic blood pressure (mean & s.D.), when measured during the last week of trainiig was significantly reduced after both leg (-10 f 8.7 mmHg) and arm (-12.4 5 9.3 mmHg P < 0.05) isometric exercise training, compared to controls. This reduction disappeared when blood pressure was measured immediately before the LBNP tests, which followed training. Orthostatic tolerance only increased after leg-training (20.8 f 16.4 LTI; P < 0.05) and was accompanied by an increased time to peak HR (119.8 4 106.3 beats mir-'; P < 0.05) in this group. Blood pressure responses to LBNP did not change after arm-training, leg-training or in controls (P > 0.05). There was a small but signiticant increase in estimated lean leg volume after leg-training (0.1 f 0.1 1; P < 0.05). These results suggest that lower resting blood pressure is probably not responsible for the increased orthostatic tolerance after isometric exercise training ofthe legs. Rather, it is possible that the training altered some other aspect of cardiovascular control during orthostatic stress that was apparent in the changes in heart rate. Legtraining was accompanied by increases in estimated lean leg volume. The effects of isometric training on orthostatic tolerance appear to be specific to limbs that are directly involved in LBNP testing. Expen 'menfal Physiology (2002) 87.4, 507-5 15.

There is some evidence to suggest isometric training can reduce resting blood pressure in a shorter period than the typical 8 weeks, reported most commonly. The purpose of the present study was to explore whether 4 weeks of bilateral-leg isometric training can reduce resting blood pressure, and whether these changes are associated with altered cardiac output or total peripheral resistance. Thirteen participants volunteered for a 4-week crossover training study, involving three sessions per week (each session involving 4 x 2 min bilateral-leg isometric exercise). The training intensity used (95% peak HR) was equivalent to 24% MVC. In addition to blood pressure, resting heart rate, cardiac output, stroke volume, and total peripheral resistance were measured. Results demonstrated that bilateral-leg isometric exercise training for 4 weeks caused significant reductions in systolic, diastolic, and mean arterial pressure. Changes were -4.9 +/- 5.8, -2.8 +/- 3.2, and -2.7 +/- 2.4 mmHg, respectively. No differences were observed in the other resting measures. In conclusion, this study has shown that it is possible to induce reductions in arterial blood pressure after 4 weeks of bilateral-leg isometric exercise.