HIIT 45

Anaerobic power and the ability to repeat it. Work intervals sit above the point where oxygen delivery can keep up, so the session is training lactate production, tolerance and clearance, and the speed at which heart rate comes back down between efforts.

The mixed-modality format means no single muscle group is the limiting factor for the whole session — legs on the bike, upper back on the erg, trunk and hips through carries and jumps. The adaptation being pursued is a higher ceiling and a faster recovery between efforts, both of which show up in everything else you do.

It suits people with an existing aerobic base who want a hard, time-efficient session and enjoy working close to the top end.

It does not suit beginners, and we will say so at the door rather than let someone have a miserable first experience of the studio. It does not suit anyone training through significant fatigue or poor sleep — the session will happen to you rather than the other way round. It does not suit anyone with a joint issue that impact aggravates; take Conditioning instead, which gets you most of the same adaptation without the landings.

Ten minutes of thorough warm-up, longer than the intensity might suggest. Progressive machine work, then movement preparation, then two or three short efforts at working pace to prime the system.

Twenty-five minutes of intervals, typically in three blocks with a full reset between them. Work periods run from twenty seconds to three minutes depending on the day; the ratio of work to rest is written on the board.

Ten minutes of cool-down and down-regulation. Easy movement, then breathing work lying down. This section is not optional and coaches will keep you there. Finishing a session with your heart rate still high and walking straight into a car park is a habit worth breaking.

Everyone works to a percentage of their own tested capacity rather than to a fixed prescription. A newer member takes longer rests and shorter work periods, keeping the quality of movement high; the coach shortens the interval rather than asking them to go slower, because slow high-intensity work is just moderate work with worse form. An experienced athlete runs full work periods, shorter rests, and heavier implements where the format allows.

Supportive trainers with a firm sole. Clothing you can move quickly in and do not mind soaking. A towel is genuinely necessary rather than polite. Bring more water than you think — this class runs at the hottest end of the day at the Marina and people routinely under-drink for it.

Once or twice a week. Three times is too much for almost everyone and is the most common reason a member plateaus for a month and cannot work out why.

It pairs well with Strength earlier in the week and with Mobility the day after. It pairs badly with Conditioning on consecutive days. If you only have three sessions a week available, one HIIT, one Strength and one Conditioning is a better week than three of anything.