The Effects of High-intensity Interval Training on Mental Health and Inflammation

The present study investigated the effects of high-intensity interval exercise training and placebo-exercise on mental health and inflammation using a randomized control trial. The study also examined how anxiety symptoms prior to high-intensity interval training may influence improvements in fitness. Inactive young adults underwent nine weeks of either high-intensity interval training or their regular routine. Questionnaires, a blood draw and a maximal exercise test were conducted the week before and week after the intervention. It was hypothesized those who underwent high-intensity interval training would experience greater reductions in their depression, anxiety, and inflammation than those who were in the placebo control group. It was also hypothesized those who had high anxiety symptoms at the start of high-intensity interval training would experience smaller improvements in fitness than those who had low anxiety symptoms.

Three sessions of high-intensity interval training per week for nine weeks. Following a three minute warm up, a session contained twenty minutes of alternating between a sprint (80% of maximum workload, 90-95% of maximum heart rate) and active rest (30% of maximum workload) at a one minute to one minute ratio. Every session ended with a two and a half minute cool down.

No changes in physical activity behaviour occurred (already engaging in less than 150 minutes per week, instructed to maintain their current inactivity). They were told they needed to stay inactive since they were part of an 'acute' exercise group, aiming to see how long the effects of their baseline maximal exercise test would last. Thus, the cover story gave them the impression they were also in an exercise group, as oppose to a non-exercise control group.

The 21-items of the Beck Anxiety Inventory (Beck, Brown, Epstein & Steer, 1998) are summed to produce a total score from 0-63, with a higher score reflecting more severe anxiety symptoms. The 21-items of the Beck Depression Inventory (Beck, Steer, & Brown, 1996) are summed to produce a total score from 0-63, with a higher score reflecting more severe depressive symptoms.

Change in concentration of circulating proinflammatory cytokines (Interleukin-6, Interleukin-1 beta, Tumour necrosis factor alpha) from baseline to post-intervention

Inclusion Criteria: Full-time student at McMaster University Speak, read and understand English Exclusion Criteria: Exercising for more than 150 minutes of moderate-to-vigorous physical activity per week

The sharing of individual data with other researchers was not included in the informed consent signed by participants. Therefore, individual data will not be released.

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