Effects of exercise training intensity and duration on skeletal muscle capillarization in healthy subjects: A meta-analysis

Publikation: Bidrag til tidsskriftReviewForskningfagfællebedømt

Purpose: This study aimed to investigate the effect of intensity and duration of continuous and interval exercise training on capillarization in skeletal muscle of
healthy adults. Methods: PubMed and Web of Science were searched from inception to June 2021. Eligibility criteria for studies were endurance exercise training >2 wk in healthy adults, and the capillary to fiber ratio (C:F) and/or capillary density (CD) reported. Meta-analyses were performed, and subsequent subgroup analyses were conducted by the characteristics of participants and training scheme. Results: Fifty-seven trials from 38 studies were included (10%/90%, athletic/sedentary). C:F was measured in 391 subjects from 47 trials, whereas CD was measured in 428 subjects from 50 trials. Exercise training increased C:F (mean difference, 0.33 (95% confidence interval, 0.30–0.37)) with low
heterogeneity (I2 = 45.08%) and CD (mean difference, 49.8 (36.9–62.6) capillaries per millimeter squared) with moderate heterogeneity (I2 = 68.82%). Compared with low-intensity training (<50% of maximal oxygen consumption (VO˙2max)), 21% higher relative change in C:F was observed after continuous moderate-intensity training (50%–80% of VO˙2max) and 54% higher change after interval training with high intensity (80%–100% of VO˙2max) in sedentary  subjects. The magnitude of capillary growth was not dependent on training intervention duration. In already trained subjects, no additional increase in capillarization was observed with various types of training. Conclusions: In sedentary subjects, continuous moderate-intensity training and interval training with high intensity lead to increases in capillarization, whereas
low-intensity training has less effect. Within the time frame studied, no effect on capillarization was established regarding training duration in sedentary subjects. The meta-analysis highlights the need for further studies in athlete groups to discern if increased capillarization can be obtained, and if so, which combination is optimal (time vs intensity). 
TidsskriftMedicine and Science in Sports and Exercise
Udgave nummer10
Sider (fra-til)1714-1728
Antal sider15
StatusUdgivet - 2022

Bibliografisk note

CURIS 2022 NEXS 225
Copyright © 2022 by the American College of Sports Medicine.

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