Members training together in the main room at O-SEA CrossFit

Starting out

The warm-up is the part of your first CrossFit class built for you.

The first minutes of exercise can feel hard for almost everyone in the room, including people who have trained for a decade. That is the stretch a beginner can misread, and it is the stretch the warm-up covers.

Start with a Free Consultation All guides

September 24, 2026 · 8 minute read

People who decide they do not belong in a CrossFit class can make that call early. It does not always happen during the workout, which they came braced for. It can happen in the first few minutes, when an easy jog or a set of slow squats has them breathing harder than seems reasonable and the person beside them looks fine. That moment feels like evidence. It is not evidence of anything. The same thing is happening inside almost every body in the room, and the part of the class built to carry you through it is the part a beginner can treat as filler: the warm-up.

Why do the first minutes of exercise feel so hard?

Many runners describe the first 10 to 15 minutes of a run as the hardest, and the cause affects almost everyone: working muscles ask for energy faster than the heart and lungs can deliver oxygen to them. Richard Taylor of Coventry University set this out in The Conversation on September 21, 2026. When you start moving, your heart rate climbs, your breathing deepens and blood is redirected toward the muscles doing the work. Those changes happen quickly, but not instantly. Physiologists call the lag oxygen uptake kinetics, and while it lasts your legs can feel heavy, your breath can feel short and a pace that should be easy can feel difficult.

Taylor is explicit that this feeling is not a verdict on fitness. He writes that it affects almost everyone, "from someone attempting their first 5K to elite endurance athletes." Trained people adjust faster, but they still go through it. Around 10 to 15 minutes in, he notes, many runners report that something changes: the body catches up with the demand and the effort settles into something manageable.

How does a first CrossFit class line up with that hard-feeling window?

A first CrossFit class at O-SEA CrossFit in San Clemente opens with a coach-led warm-up, then instruction on the movements of the day, then the workout itself, then a cool-down. The warm-up sits across the front of the window Taylor describes, the minutes when your body has not yet caught up with what you are asking of it. Taylor calls a gradual warm-up "perhaps the most effective strategy" for getting through that adjustment, because it gives the heart, lungs and muscles time to match up before the effort that counts.

Seen that way, the warm-up in a CrossFit class is not a formality before the real session. It is the stretch of the hour that can absorb those early minutes at low stakes: nothing is timed, nothing is scored and nobody is chasing a number on the board. By the time the workout starts, you may already be through the adjustment Taylor describes.

Why might a beginner decide in minute five that they do not belong?

A beginner can decide early in a first class that they are out of their depth, because the first minutes of exercise can produce a feeling that looks exactly like proof. You are breathing hard through a movement the coach described as easy. You can feel your own heart rate and you cannot feel anyone else's, so the comparison only runs one way: how you feel inside against how everybody else looks from outside.

Jenny Meggs, a sports psychology lecturer at Lancaster University, lists "fear of being judged by other people" among the reasons people stay away from gyms, and in The Conversation she cites one survey that found as many as half of Americans experience what she calls gymtimidation. That figure is reported secondhand, not from a study we can inspect, so it is best read as a sign the fear is common rather than as a precise count. The timing matters more than the number. The fear of being judged is likely to be loud at the start of a first class, and the start is also when the body can feel least capable. The two can arrive together, and a newcomer can read the second as confirmation of the first.

Does a member who has trained for ten years feel it too?

A member who has trained for ten years goes through a version of the same adjustment at the start of class. Taylor's point is that the lag between effort and oxygen supply is a normal feature of how bodies move from rest to work, and that training shortens it rather than removing it. The experienced member's version is shorter, and they stopped reading meaning into it a long time ago.

That is the real difference between a first-timer and a long-time member in the opening minutes of a class: not whether it feels hard, but whether they believe the feeling. Meggs makes the same point about nerves, noting that even people who have attended for a long time feel them, and calling it "a perfectly normal part of the process of trying something new." The fear that everyone is watching you struggle in the warm-up misses something simple. Almost everybody in the warm-up is in the middle of their own adjustment, not watching yours.

What should you do differently in your first class, knowing this?

Knowing about the adjustment window before a first CrossFit class changes how the first ten minutes read, and it changes a few practical choices.

Expect the warm-up to feel harder than it looks. That is the adjustment Taylor describes, not a ceiling on what you can do. Move at the pace the coach gives you rather than the pace of the person beside you; Taylor's own advice to runners is to start slower than you intend. Do not decide anything about whether you belong until the warm-up is over and your breathing has settled. If the workout still looks like too much once it is explained, tell the coach. At O-SEA every movement has a scaled version, and choosing it is what the scaled version is for.

One more: arrive early enough not to miss the warm-up. A beginner who slips in late and goes straight into the workout skips the part of the hour designed for them and meets the adjustment window at full effort, which is the worst place to meet it.

Is this just the old advice to always warm up, dressed up?

The strongest case against this essay is that warming up before exercise is the most familiar advice in fitness, and calling the warm-up the part built for beginners overstates something everyone already knows. There is a second problem. Taylor wrote about running, and a CrossFit class mixes squats, rowing, lifting and bodyweight movements, so his description may not map cleanly onto the hour. And a warm-up does not make the first minutes feel easy. Some newcomers will still find them hard.

All three objections are partly right. The claim here is not that warm-ups are new, or that they erase the discomfort. It is narrower: the warm-up is when a newcomer is most likely to misread normal physiology as unfitness, and it is the lowest-stakes place to have that experience. The gap between running and a CrossFit class is real, and the evidence here is thin on it: neither source measures the adjustment inside a mixed group class. What plausibly carries over is the principle behind Taylor's account, that moving from rest to effort takes the body time.

The familiar advice tells you what to do. It says nothing about what the warm-up will feel like, or what not to conclude from it. That missing part can be what sends people home after one class.

Who is a first CrossFit group class not right for?

A first CrossFit group class is not the right starting point for everybody, and saying so is part of describing it honestly.

If you have a health condition, a recent injury or have been told to limit exertion, talk to your own doctor before any first class; nothing here is a substitute for that conversation. If you would rather learn the movements before standing in a room with other people, starting with a group class is the wrong order. O-SEA runs an On-Ramp program for learning the movements first. If you want to train alone, headphones in, with nobody saying hello, a group class will not suit you. And if what you want is for the hard opening minutes to disappear entirely, no class delivers that. Training shortens the adjustment. It does not remove it.

The difference between a first-timer and a ten-year member in the first minutes is not whether it feels hard, but whether they believe the feeling.

The warm-up gets treated as the part of the hour before the class really starts. For somebody walking in for the first time, it is closer to the opposite. The minutes when the body is still catching up happen there, for the beginner and the veteran alike, before anything is timed or scored. If you know that going in, minute five stops looking like the moment you found out you did not belong. It is just minute five.