Isometric exercise versus high-intensity interval training for the management of blood pressure: a systematic review and meta-analysis

2021 ◽  
pp. bjsports-2021-104642
Author(s):  
Jamie Edwards ◽  
Anthony De Caux ◽  
James Donaldson ◽  
Jonathan Wiles ◽  
Jamie O'Driscoll

ObjectiveWe aimed to compare the efficacy of isometric exercise training (IET) versus high-intensity interval training (HIIT) in the management of resting blood pressure (BP).DesignSystematic review and meta-analysis.Data sourcesPubMed (MEDLINE), the Cochrane library and SPORTDiscus were systematically searched.Eligibility criteriaRandomised controlled trials published between 1 January 2000 and 1 September 2020. Research trials reporting the effects of IET or HIIT on resting BP following a short-term intervention (2–12 weeks).Results38 studies were analysed (18 IET and 20 HIIT), including 1583 (672 IET and 911 HIIT) participants, of which 612 (268 IET and 344 HIIT) were controls.IET produced significantly greater reductions in resting BP compared with HIIT with systolic, diastolic and mean BP effect sizes of 8.50 mm Hg vs 2.86 mm Hg (Q=17.10, p<0.001), 4.07 mm Hg vs 2.48 mm Hg (Q=4.71, p=0.03) and 6.46 mm Hg vs 3.15 mm Hg (Q=4.21, p=0.04) respectively. However, HIIT reduced resting heart rate significantly more than IET (3.17bpm vs 1.34bpm, Q=7.63, p=0.006).ConclusionWhile both modes are efficacious, IET appears to be the superior mode of exercise in the management of resting BP. However, HIIT may achieve wider physiological benefits, with greater reductions in resting heart rate.

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3674
Author(s):  
Tak Hiong Wong ◽  
Alexiaa Sim ◽  
Stephen F. Burns

Dietary nitrate supplementation has shown promising ergogenic effects on endurance exercise. However, at present there is no systematic analysis evaluating the effects of acute or chronic nitrate supplementation on performance measures during high-intensity interval training (HIIT) and sprint interval training (SIT). The main aim of this systematic review and meta-analysis was to evaluate the evidence for supplementation of dietary beetroot—a common source of nitrate—to improve peak and mean power output during HIIT and SIT. A systematic literature search was carried out following PRISMA guidelines and the PICOS framework within the following databases: PubMed, ProQuest, ScienceDirect, and SPORTDiscus. Search terms used were: ((nitrate OR nitrite OR beetroot) AND (HIIT or high intensity or sprint interval or SIT) AND (performance)). A total of 17 studies were included and reviewed independently. Seven studies applied an acute supplementation strategy and ten studies applied chronic supplementation. The standardised mean difference for mean power output showed an overall trivial, non-significant effect in favour of placebo (Hedges’ g = −0.05, 95% CI −0.32 to 0.21, Z = 0.39, p = 0.69). The standardised mean difference for peak power output showed a trivial, non-significant effect in favour of the beetroot juice intervention (Hedges’ g = 0.08, 95% CI -0.14 to 0.30, Z = 0.72, p = 0.47). The present meta-analysis showed trivial statistical heterogeneity in power output, but the variation in the exercise protocols, nitrate dosage, type of beetroot products, supplementation strategy, and duration among studies restricted a firm conclusion of the effect of beetroot supplementation on HIIT performance. Our findings suggest that beetroot supplementation offers no significant improvement to peak or mean power output during HIIT or SIT. Future research could further examine the ergogenic potential by optimising the beetroot supplementation strategy in terms of dosage, timing, and type of beetroot product. The potential combined effect of other ingredients in the beetroot products should not be undermined. Finally, a chronic supplementation protocol with a higher beetroot dosage (>12.9 mmol/day for 6 days) is recommended for future HIIT and SIT study.


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