Flying is a mental, not a physical game.

Dr Matt Wilkes wearing the Metamax mask in flight over Laragne, measuring the oxygen and energy consumption of XC flight.

Our moderate altitude flights represented the ‘minimum’ effort required to fly paragliders about 50 km cross-country. Except for take-off and spiralling down, we found that for a 70 kg individual, paragliding consumed approximately 30 watts of energy, or 120 kcal, per hour. That’s equivalent to walking at a speed of 3 km per hour or about one third of a Snickers bar. Flying in stressful, very cold or high-altitude conditions would likely increase this energy requirement, but as a baseline, paragliding does not require a lot of physical effort.

It may require a lot of mental effort but because the brain is in a constant state of flux, thinking hard doesn’t noticeably increase your oxygen and energy requirements as calculated by the Metamax mask. Your brain does still need food and liquid to function properly though.

Key messages

Any exhaustion felt following a long paragliding flight is likely not physical, but more like the tiredness felt following a long drive. The brain might be in overdrive, but the body isn’t working very hard. It is experience, not physical fitness that holds the key to flying safely for long periods.

1. Be alert to the effects of cognitive fatigue.
2. Pay attention to your comfort.
3. Eat little and often during flight. Regular snacks that mix sugars, protein and salt (for example, trail mix) along with water will help you stay hydrated and at your best.
4. Build up gradually to longer flights.

Take-off, Landing and Ground Handling: Brief Bursts of Effort

The 30-watt baseline measured by Dr Wilkes and his team deliberately excluded the moments of take-off and spiral descent, because these are the exceptions to the rule. On the ground, a paraglider pilot must often run with a wing inflated overhead, carrying a harness, reserve parachute, helmet and various instruments that together weigh between 12 and 18 kg. A poorly executed inflation can turn into a sprint of 30 metres or more, pushing heart rate and oxygen consumption far above the airborne average. Even a well-judged reverse launch in strong wind still requires several seconds of coordinated pulling, stepping and braking that would register on any metabolic mask.

The good news is that technique matters far more than brute strength. A pilot who reads the wind correctly and times the inflation can launch almost effortlessly, letting the wing rise and then simply leaning back into the harness. By contrast, a pilot who hesitates or over-controls the brakes may end up fighting the wing, burning energy equal to a short stair climb. The same applies to landing: a smooth top-landing or a gentle flare in a laminar breeze demands little more than standing up, while a turbulent approach or a tight field may require rapid weight shifts, a short run, and a controlled collapse of the wing.

None of these bursts are long enough to tax the aerobic system, but they do rely on a basic level of leg strength, balance and coordination. For pilots who hike to launch, the walk or climb with all the kit is usually the most physically demanding part of the entire day, often exceeding the energy burned during several hours of flying. So while in-flight effort is low, the bookends of a flying day still reward a reasonable level of general fitness.

Muscular Fatigue from Static Posture and Weight-shift Control

Even at a metabolic rate of only 30 watts, the body is not completely passive. Sitting in a paragliding harness for three or four hours requires continuous low-level contraction of the core muscles, hip flexors and neck extensors to hold the body in a stable position. The legs may dangle or rest on the speed bar, but the lumbar spine and abdomen are constantly adjusting to small swings of the pod. Over time, this static loading produces local muscular fatigue, stiffness and pressure-point discomfort, particularly in the lower back, buttocks and inner thighs.

Weight-shift steering adds another layer of subtle but repeated effort. To turn a paraglider, the pilot shifts weight to one side by tilting the pelvis and pressing against the side of the harness. Each correction during a thermal climb or a turbulent glide involves dozens of tiny contractions of the obliques, gluteals and quadratus lumborum. Over the course of a four-hour cross-country flight, a pilot may perform several thousand of these micro-adjustments. The total mechanical work is tiny, but because the same small muscles are recruited again and again without rest, they can feel surprisingly sore by the end of the day.

This explains why many pilots report aching hips, a stiff neck or a tired lower back after a long flight, despite having barely raised their heart rate. A well-fitted harness with a firm seat plate and good back support reduces the load, as does a cocoon style that distributes pressure more evenly. Simple in-flight movements—straightening the legs, arching the back gently, rolling the shoulders, or pulling the knees up for a minute—help restore blood flow and delay the onset of cramping. The effort level may be low, but comfort management is still a physical skill worth practising.

When Conditions Raise the Physical Demand

The 30-watt figure is a baseline measured in moderate conditions: smooth thermals, mild temperatures and altitudes below 2,000 metres. As soon as the environment becomes more demanding, energy expenditure climbs. Cold air triggers shivering, which can increase metabolic rate by a factor of three to five, even inside a warm flying suit. High altitude reduces the partial pressure of oxygen, so every muscle contraction requires a greater cardiovascular response. And strong turbulence forces the pilot to actively weight shift, brace against surges and make constant corrective brake inputs, turning a passive glide into a continuous low-level workout.

Consider a pilot flying in the high Alps on a cold, blustery day. At 3,500 metres, the available oxygen is only about 65% of sea-level values. To maintain the same 30 watts of output, the heart must beat faster and the breathing rate must increase. Add a rough lee-side crossing with repeated collapses and recoveries, and the pilot may be doing the equivalent of slow walking or even light cycling for periods of several minutes. Over the course of a six-hour flight, this can add up to several hundred extra kilocalories and a noticeable feeling of physical tiredness.

It is important to keep perspective: even a very demanding paragliding flight rarely exceeds the effort of a brisk walk or a gentle bike ride. But the combination of cold, altitude and turbulence can amplify the baseline dramatically. Pilots who fly in such conditions should treat the day as they would a moderate hike—dress in layers, eat and drink regularly, and accept that the physical toll will be higher than the Metamax mask recorded on a calm summer afternoon.

Fuel for the Brain: Nutrition and Hydration in the Air

Although the whole body burns only about 120 kilocalories per hour during paragliding, the brain alone accounts for roughly 20% of resting energy expenditure, close to 15–20 watts in a typical adult. The Metamax measurements showed that hard thinking does not noticeably increase total oxygen consumption, but that does not mean the brain can run on empty. Neurones require a steady supply of glucose, and blood sugar levels decline slowly even during sedentary mental work. After two or three hours without food, reaction times lengthen, decisions become sloppier and the pilot may miss subtle signs of changing air.

Practical in-flight nutrition is therefore less about replacing muscle glycogen and more about keeping the brain fed. Good options include:

• Small pieces of energy bar, dried fruit or nuts eaten every 30–45 minutes
• 100–200 ml of water per hour, more in heat or at high altitude
• Electrolyte tablets or diluted sports drinks for flights lasting over four hours
• Avoiding large, fatty meals immediately before launch, which divert blood to digestion and cause drowsiness

Dehydration deserves special attention. Losing just 1–2% of body weight through fluid loss—about 700 ml to 1.4 litres for a 70 kg pilot—has been shown to impair short-term memory, attention and visual tracking. In a paraglider, where the pilot must constantly scan the sky, interpret cloud development and make rapid decisions about heading and speed, even mild dehydration can be as dangerous as physical exhaustion. The advice to “eat little and often” is not a courtesy suggestion; it is a fundamental part of managing the mental workload of a long cross-country flight.

This is a summary of one of our key findings from Phase I of the Free Flight Physiology Project. For a full write up of our methods and results, please see our our Cross Country Magazine article or our scientific paper in High Altitude Medicine and Biology.