The last long-haul I took was to a race in Scotland with Deso. Twelve hours door to door, two flights, one toddler-aged son who decided sleep was for other people. I stepped off the second plane and my calves felt like sandbags, my lower back was angry in a very specific spot just left of my sacrum, and my right hip flexor had gone on strike. Within forty minutes of getting to the hotel I had it sorted. Not because I'm special — because I know what's happening underneath the discomfort, and I have a small set of habits I refuse to skip.
This is the article I wish someone handed me before my first long flight as a physiotherapist who runs ultras. No products, no hype. Just what the human body does inside a metal tube at altitude for ten-plus hours, and the behaviour that lets you walk off the plane feeling like a person.
What Actually Happens to Your Body at 35,000 Feet
Long flights don't just bore you. They quietly load your tissues in ways that are very different from sitting at your desk. The cabin is low-pressure (roughly equivalent to being at 1,800–2,400 metres of altitude), the air is dry (often under 20% humidity), and you're held in one position by a seat designed by someone who has clearly never had a sacrum. Stack those three things on top of 10+ hours and you get a predictable cascade.
The lumbar spine: held in flexion, then punished
Airplane seats push your pelvis into a posterior tilt. Your lumbar spine, which should have a gentle forward curve (lordosis), is forced into the opposite shape — slight flexion, sometimes for hours at a stretch. The discs in your lower back tolerate compression well, but they don't love sustained flexion combined with vibration (yes, the plane is vibrating the whole time, even when it feels smooth). The posterior annulus — the back of the disc — gets a slow, low-grade load that it isn't designed for.
What you feel when you stand up: that stiff, locked sensation in the lower back, sometimes a sharp catch when you first straighten. That isn't damage. It's tissue creep — the ligaments and discs have adapted to the shape you held, and they need a minute to remember how to be upright. People who already have a cranky back feel this far more. I've written about this exact mechanism in the context of lifting a toddler with a bad back — same principle, different trigger.
The hips: flexors shortened, glutes asleep
Hip flexors (psoas, iliacus, rectus femoris) sit in a shortened position the entire flight. Your glutes, meanwhile, get switched off — there's nothing for them to do while you're sitting on them. Ten hours of this and you stand up with what feels like a tight front-of-hip and a back that's doing the work your glutes should be doing. This is exactly the pattern I see in desk workers who can't figure out why their lower back hurts when they run.
The calves and ankles: the swelling story
This is the big one, and the one most people ask me about. The calf muscle is what we call a "venous pump." Every time you contract it — walking, even just shifting your weight — it squeezes the deep veins and pushes blood back up toward the heart against gravity. When you sit motionless for hours, that pump stops working. Blood pools in the lower legs. Fluid leaks out of the capillaries into the surrounding tissue because hydrostatic pressure goes up. The result: long flight leg swelling, that puffy, tight, shoes-don't-fit-anymore feeling.
Add the cabin's low pressure (which slightly favours fluid leaving the vessels) and the dehydration from dry air (which makes the blood more viscous), and you have the conditions that, in a very small number of people with other risk factors, set the stage for deep vein thrombosis. For most of us it's "just" swelling and stiffness — uncomfortable but not dangerous. Still worth taking seriously.
The neck, shoulders, and everything above
Sleeping upright with your head unsupported is a slow torture for the cervical spine. Your head weighs about 5 kg, and any time it drifts forward of your shoulders, the load on the upper trapezius and the deep neck extensors multiplies. By hour six you've essentially done a half-marathon for your neck muscles. The mechanism is the same one I broke down in my piece on forward head posture — just compressed into a single overnight flight.
My Seated In-Flight Mobility Routine (Done Every 60–90 Minutes)
This is what I actually do, in my seat, without disturbing the person next to me. The whole thing takes about three minutes. Do it every time the meal cart goes past, or set a watch alarm.
1. Ankle pumps and circles (60 seconds)
Lift both feet slightly off the floor. Point the toes hard, then pull them up toward your shins hard. Twenty repetitions. Then draw twenty slow circles with each foot, in both directions. This is the single most important thing on this list. It's directly working the calf venous pump. This alone significantly reduces leg swelling.2. Glute squeezes (30 seconds)
Sit tall and squeeze your glutes as hard as you can for five seconds. Release. Repeat ten times. Nobody can see you doing this. It wakes up the muscles that have been switched off and gives your lumbar spine a brief break from being the only thing holding you upright.3. Seated pelvic tilts (30 seconds)
Slowly rock your pelvis forward (arching your lower back slightly) and then backward (rounding it). Small movements, ten of each. This nudges the lumbar discs through their range and undoes some of the creep.4. Thoracic rotations (30 seconds)
Cross your arms over your chest. Rotate your upper body slowly to the right as far as it goes, then to the left. Five each side. Your thoracic spine — the mid-back — stiffens up fast on flights, and a stiff mid-back forces the lumbar and neck to take up the slack.5. Chin tucks (30 seconds)
Gently draw your chin straight back (not down — back, like you're making a double chin). Hold three seconds. Repeat ten times. This counteracts the forward head drift from screens and seat-back posture.6. Stand up every two hours minimum
Walk to the back of the cabin. Do ten calf raises holding onto a seat. Do a slow standing forward fold and roll up one vertebra at a time. I genuinely don't care if I'm in the way. The risk of pretending to be polite for ten hours is worse than the social cost of stretching in the galley.Hydration, Caffeine, and the Things That Sabotage You
Cabin humidity is roughly that of a desert. You're losing fluid through breath alone at a much higher rate than on the ground. Dehydration thickens your blood, worsens swelling rebound (yes, paradoxically), and makes jet lag worse.
My rules, refined over a lot of flights:
- One glass of water per hour, minimum. I carry a one-litre bottle through security empty and fill it after. I refill from the galley. I drink it whether I'm thirsty or not.
- Coffee: yes, but early. One cup at the start is fine and won't meaningfully dehydrate you. A second cup six hours in will wreck your sleep on the other side.
- Alcohol: no. I know it's free in business class. It dehydrates you, disrupts the sleep architecture you do manage to scrape together, and worsens the next-day inflammatory feeling. Save it for landing.
- Salt: a small amount helps. A pinch of salt in your water or a salty snack helps you hold the fluid you're drinking rather than just peeing it out.
- Compression on the legs. Graduated compression around the calves keeps the venous return working even when your muscle pump is dozing. This is one of the few interventions with solid evidence behind it for circulation on long haul flights. I wrote a detailed mechanism breakdown in my piece on how compression actually affects circulation if you want the physiology.
The 20-Minute Land-and-Loosen Routine
This is what I do in the hotel room within an hour of arriving. It is not optional. Skipping it is the difference between feeling 70% the next morning and feeling 95%.
Minutes 0–3: Walk and breathe
Walk around the room or the hallway for three solid minutes. Don't stretch yet. Let blood move. Take slow nasal breaths in for four counts, out for six. This nudges your nervous system out of the wired-but-tired state long flights leave you in.Minutes 3–6: Calves and ankles
Stand facing a wall, hands on it. Step one foot back and press the heel down into a calf stretch. 45 seconds each side, then 45 seconds with the back knee slightly bent (this targets the deeper soleus muscle). Finish with 20 slow calf raises. You're flushing out the fluid that's pooled all day.Minutes 6–10: Hips
Low lunge: front foot flat, back knee on the floor (use a pillow). Tuck your pelvis under and press gently forward. 60 seconds each side. This is the antidote to ten hours of shortened hip flexors. Then a figure-four stretch lying on your back, 60 seconds each side, for the deep hip rotators that have been compressed in the seat.Minutes 10–14: Lower back
Cat-cow on hands and knees, slow and full-range, 10 reps. Then child's pose with your arms reaching forward, 60 seconds, breathing into your lower back. Then a gentle supine spinal twist, 45 seconds each side. You're undoing the lumbar flexion creep without forcing anything.Minutes 14–17: Thoracic and neck
Thread-the-needle on hands and knees, 8 each side. Doorway pec stretch, 45 seconds each arm. Standing chin tucks, 10 reps. Slow head turns and gentle side bends, 5 each direction. Your upper back has been hunched and your pec minor has been short — this opens the chest and frees the neck.Minutes 17–20: Reset walk
Walk around the room again. Shake your legs out. Roll your shoulders. Drink a full glass of water. If you have access to a hot shower, take one and finish with 30 seconds of cool water on your legs from the knees down — it nudges the vascular system to flush.That's it. Twenty minutes. I have done this in airport hotels, in cramped Airbnbs, in a tent at a race, and once standing next to my suitcase in a hostel hallway. It works every time.
Post-Flight Recovery: The 48-Hour Plan
If you can get a 20-minute walk outside in daylight within a few hours of landing, do it. Sunlight resets your circadian rhythm faster than anything else, and the walking finishes the job of flushing your legs.
Sleep on your side with a pillow between your knees. This keeps the lumbar spine neutral and stops one hip from being pulled into adduction — I explain why in the sciatica sleeping positions piece, and the same logic applies to any travel-stiffened back.
Don't do your first hard training session within 24 hours of landing. Your tissues are dehydrated, your sleep is fragmented, and your proprioception is slightly off. This is exactly when people roll ankles and tweak hamstrings. Easy aerobic movement only on day one — a walk, a swim, easy bike. Real training on day two.
Eat early in the local time zone, even if you're not hungry. Food timing is a powerful jet lag cue. Protein at the first meal helps your tissue recovery from the flight itself.
A Note on Who Needs to Be Extra Careful
If you're pregnant, recovering from surgery, have varicose veins, a history of clots, or you're over 65 and relatively sedentary, the standard advice applies more strictly: graduated compression on the legs is not optional, hydration is non-negotiable, and you should be walking the cabin every 60 minutes rather than every 90. If you have any leg pain that's localised, hot, or one-sided after a flight, that's a doctor visit, not a stretching session.
For everyone else: long flights aren't doing permanent damage. They're just stressing tissues in ways those tissues aren't used to. The discomfort you feel afterward is your body's way of telling you to undo what just happened — and now you know exactly how.
The next time you have a 10-hour flight, you're not at the mercy of the seat. You have a seated routine, a hydration plan, and a 20-minute reset that takes less time than scrolling on your phone in the hotel lobby. Use them. You'll land feeling human.