The effects of high intensity interval training on quality of life: a systematic review and meta-analysis.

Aim:
This study aimed to ascertain the impact of high intensity interval training (HIIT) on physical, mental, and overall quality of life (QoL) through a comprehensive systematic review and meta-analysis.

Subject and Methods:
A systematic search for relevant trials was performed via PubMed, the Cochrane Library and Web of science as well as the manual screening of prior meta-analyses and their respective reference lists (PROSPERO reference: CRD42022326576). Adult controlled trials investigating the effects of a >2-week HIIT intervention with an eligible non-intervention control group were considered. As the primary outcome, studies were required to include at least one measure of physical and/or mental and/or overall QoL, on any validated QoL domain, pre and post intervention.

Results:
Twenty-two studies with twenty-four effect sizes were included; seventeen comparing HIIT and overall QoL, fourteen comparing HIIT and physical QoL and thirteen studies comparing HIIT and mental QoL. There was a statistically significant improvement in physical (SMD= 0.405, 95% CI: 0.110- 0.700, p= 0.007), mental (SMD= 0.473, 95% CI: 0.043 –0.902, p=0.031) and overall QoL (SMD= 0.554, 95% CI 0.210-0.898, p=0.002) following a program of HIIT. Secondary analysis of 5 studies comparing HIIT against moderate intensity continuous training demonstrated no significant difference in improvement between the two modes (SMD= -0.094, CI= -0.506-0.318, p=0.655).

Conclusion:
Engaging in HIIT produces statistically significant improvements in physical, mental, and overall quality of life in clinical and non-clinical populations at a small to moderate effect size. Furthermore, HIIT appears as effective as MICT in improving overall QoL, offering a more time-efficient exercise option.