VO₂ Max for Outdoor Athletes: What Surfers, Trail Runners, and Mountain Bikers Need to Know

Almost everything written about VO₂ Max assumes you're a road cyclist clipped into a power meter or a runner logging splits on a flat track. The benchmark tables are built around those sports. The training recommendations read like they were written for someone on a Peloton in a climate-controlled room.

Here in Santa Cruz, most of the people who walk into our gym don't live in that world. They paddle out at Pleasure Point at dawn. They run the fire roads above UCSC on their lunch break. They spend Saturday mornings climbing through Soquel Demonstration Forest on a full-suspension bike. These are serious athletes with serious aerobic demands, and virtually none of the VO₂ Max content on the internet speaks to them.

We hear the same question constantly: "I don't race road bikes or run marathons. Does this test actually matter for what I do?"

It does. But how it matters, and which parts of the data you should focus on, depends on your sport.

Why most VO₂ Max content misses outdoor athletes entirely

The VO₂ Max test was born in exercise physiology labs using treadmills and cycle ergometers, modalities that are controllable, repeatable, and easy to standardize. The research, the norms tables, and the coaching recommendations all grew out of those controlled environments. When you Google "good VO₂ Max for a 35-year-old," the charts don't differentiate between a 35-year-old who surfs two hours a day and one who runs 10Ks.

Outdoor athletes also use their aerobic systems differently. A trail runner surges uphill and recovers on descents. A surfer paddles hard, rests on the lineup, then explodes into a wave. A mountain biker alternates between grinding climbs and technical descents. These intermittent, variable-intensity patterns are where VO₂ Max matters most and where it's discussed least. Your aerobic ceiling determines how quickly you recover between efforts, how many waves you can catch before your arms give out, and whether you can clear the last climb at Demo without blowing up.

Surfing: the aerobic sport nobody calls aerobic

If you ask most surfers whether they think about aerobic fitness, they'll talk about arm strength or shoulder endurance. Paddling feels like an upper-body effort. But the energy system driving that effort is overwhelmingly aerobic.

Research on competitive surfers shows that roughly 60% of a typical surf session is spent paddling, and most of that paddling happens at an intensity right around VT1, the first ventilatory threshold where your breathing shifts from easy to managed. The remaining time splits between sitting in the lineup, short bursts of high-intensity paddling to catch waves, and the actual riding, which is brief and accounts for a surprisingly small percentage of total session time.

First, your VO₂ Max predicts your session endurance. A surfer with a higher aerobic ceiling recovers faster in the lineup between sets and still has gas in the tank at the ninety-minute mark. We see this directly with our clients who surf at Steamer Lane and Pleasure Point: the ones with higher tested scores consistently report longer productive sessions, especially on big days when the current is working against them.

Second, and this is the part most surfers miss, your VT1 is more important than your VO₂ Max score. Since the majority of paddling happens near VT1, the higher that threshold sits relative to your ceiling, the more work you can do before crossing into the gray zone where fatigue accumulates. Two surfers can have the same VO₂ Max of 42, but if one has a VT1 at 65% of max and the other at 75%, the second surfer will paddle more efficiently and feel less wrecked after a two-hour session.

We also watch the respiratory exchange ratio. If a surfer is burning disproportionate carbohydrate at paddling-level effort, their aerobic base needs work, and that explains why they bonk halfway through a session even though they feel "fit."

One training tip for surfers

Take your tested VT1 heart rate and use it to cap your paddle-conditioning sessions: pool paddles, prone paddleboard work, rowing machine intervals. Keep sustained portions at or just below that number. Most surfers we work with train their paddling too hard. They hammer every session, spend most of their time in the gray zone between VT1 and VT2, and wonder why endurance doesn't improve. Drop the intensity, extend the duration, and let the aerobic base do its job.

Trail running: where Santa Cruz terrain meets test data

Trail runners are closer to the traditional VO₂ Max testing population than surfers or mountain bikers, but there's a critical wrinkle: elevation change. In Santa Cruz, that wrinkle is constant.

If you run Wilder Ranch, the UCSC fire roads, or the paths through Henry Cowell and Nisene Marks, flat ground barely exists. Your heart rate is never steady. You're surging above VT2 on steep pitches and dropping well below VT1 on the downhills. The average intensity might look moderate, but the actual demand is a series of high spikes and short recoveries that tax your aerobic system very differently than running the same distance on flat road.

Your VT2 tells you the upper boundary of what you can sustain on climbs. When you hit a steep section, your heart rate rockets up. If it crosses above VT2, you're accumulating lactate that you'll have to clear on the next flat or downhill. The higher your VT2 sits, the steeper the grade you can handle without going into oxygen debt.

Standard test protocols ramp up speed and incline in a controlled progression, but Santa Cruz trail grades make Bruce protocol stages look gentle: 15% to 25% on some Wilder fire roads, steeper on single track. Your test gives you heart rate anchors for your thresholds, and those anchors hold regardless of terrain. VT2 is VT2 whether you're on a treadmill or grinding up the Enchanted Loop.

The practical difference is pacing strategy. Road runners hold a pace. Trail runners need to hold a heart rate, and the test gives them the specific heart rates that matter.

One training tip for trail runners

Use your VT2 heart rate as a hard cap on uphill efforts during base-building phases. When the trail kicks up and your heart rate starts climbing toward VT2, slow down or walk before you cross it. This feels wrong; every instinct says push through. But staying below VT2 on climbs builds the engine that eventually lets you push those hills faster without redlining. It's polarized training applied to real terrain, and your tested thresholds are the only way to do it with precision instead of guesswork.

Mountain biking: where VT2 is the whole game

If surfing is a VT1 sport and trail running oscillates across both thresholds, mountain biking (at least the kind we see in Demo Forest, Wilder Ranch, and the trails off Soquel-San Jose Road) is a VT2 sport.

The climbing in these trail systems is sustained: ten-, fifteen-, even twenty-minute efforts on fire roads and connectors that demand steady, hard output. Your heart rate sits right around VT2 for most of these climbs. If VT2 is low, those climbs bury you. If VT2 is high, those same climbs feel challenging but manageable, and you arrive at the top with enough composure to ride the technical descent without your arms shaking.

For mountain bikers, VT2 is the critical metric from the test, not the VO₂ Max score itself. Two riders can have identical VO₂ Max values but wildly different VT2 thresholds. The one with the higher VT2 relative to their ceiling will handle sustained climbs better, recover faster on short flat sections, and maintain technical focus deeper into a ride.

Mountain bikers also benefit from understanding their VO₂ Max in the context of sport-specific benchmarks. Cycling norms are typically reported for road cyclists at sustained power. Mountain biking power delivery is irregular: rock gardens, berms, inconsistent cadences. The raw number matters less than the threshold architecture underneath it.

One training tip for mountain bikers

Pick one sustained climb you ride regularly, eight to fifteen minutes. Ride it with a heart rate monitor and hold your effort at your tested VT2 heart rate. Don't surge at the bottom. Don't sprint the last pitch. Hold VT2 the entire way up, once a week for six weeks. Your speed at that heart rate will start to increase: more power at the same metabolic cost. That's the definition of getting fitter for climbing, and the test gave you the exact number to target.

Choosing the right test protocol for your sport

The protocol you use matters more for outdoor athletes than for the general population. We cover this in depth in our guide on treadmill vs. bike protocol selection, but here's the short version.

Trail runners: Treadmill protocol. The muscle recruitment, weight-bearing demands, and cardiovascular response map closely to trail running. A ramp protocol with progressive grade increases mimics the climbing you encounter on Santa Cruz trails.

Mountain bikers: Bike protocol. Cycling-specific tests use a ramp on a stationary bike or your own bike on a smart trainer. The thresholds correspond to heart rates and power outputs that directly apply to your riding.

Surfers: There's no standard paddle ergometer protocol for VO₂ Max testing. We typically test surfers on a bike protocol because it's lower-impact and produces reliable threshold data without running-specific fatigue that can limit a non-runner's performance. The heart rate-based thresholds transfer to paddle conditioning even though the muscle groups differ. Not perfect, but far more useful than not testing at all.

If you're not sure which protocol fits your situation, that's exactly what the intake conversation is for. We build a test designed with protocol choice for your sport, not a one-size-fits-all template.

The outdoor athlete's advantage

Outdoor athletes who train in variable, unpredictable environments tend to have more robust aerobic systems than their numbers alone would suggest. A surfer with a VO₂ Max of 38 who paddles in cold water and fights currents often outperforms a gym-trained athlete at 42 who only knows the treadmill.

The test measures capacity. It doesn't measure resilience or adaptability. Those qualities are developed by doing the thing. The test supplements that with precision: a map of where your aerobic system transitions to the anaerobic system, where sustainable effort becomes unsustainable, where you're leaving capacity on the table. That map works whether you're in our gym or on a surfboard at the Lane.

If you've been training by feel and wondering whether you're actually getting fitter, the test answers that question. We've built it for the athletes who live here, not the ones in the textbooks.

Book your evaluation here and tell us what you do. We'll match the protocol to your sport and give you data you can actually use the next time you paddle out, lace up, or clip in.