Uphill VMA: how to understand, measure, and use a key indicator for trail and long-distance performance
VMA (vVO₂max) is a cornerstone of training… on flat terrain. As soon as grade increases, speed, energy cost, and muscular constraints change dramatically. This article provides a deep, evidence-minded framework (physiology, biomechanics, protocols) to make uphill VMA a credible tool for trail, pacing, and long races.
What VMA really measures
VMA (vVO₂max) is the speed at which oxygen consumption reaches its maximum. It represents the highest intensity that fully stresses the aerobic system, usually assessed via incremental tests and then used to prescribe training intensities.
Common misconceptions: VMA is not a sustainable pace; it depends on VO₂max, running economy (energy cost), and neuromuscular factors (coordination, ability to produce speed).
Practically, it’s used as a relative reference: easy endurance at ~60–70% VMA, tempo/threshold around ~80–90%, VO₂max work near ~95–105%. The catch: most of these references are derived from flat running and transfer imperfectly to steep terrain.
Why flat VMA is not enough uphill
As grade increases, multiple mechanisms reshape the relationship between speed, effort, and energy demand. Speed becomes a poor proxy for intensity, especially on moderate to steep climbs.
A much higher energy cost per meter
Uphill running increases the work against gravity. The energy cost per meter rises sharply while horizontal speed drops. Beyond ~8–10% grade, comparing “pace per kilometer” becomes increasingly misleading.
As a result, an athlete can be near maximal aerobic output at a very low horizontal speed simply because vertical work is high.
Different biomechanics and muscle demands
Uphill movement typically involves shorter stride length, higher cadence, and a stronger vertical propulsion component. Depending on grade and intensity, locomotion shifts toward a run/hike hybrid.
Concentric muscle work (quads, calves, glutes) increases, and uphill economy becomes highly discriminative.
Weaker correlation with trail performance
Two athletes with identical flat VMA can perform very differently uphill. Conversely, runners with modest road speed may climb extremely well due to high relative strength, good uphill economy, and better local muscular endurance.
Operational takeaway: flat VMA remains useful, but it is often a weak predictor of sustained uphill intensity—especially in trail and long races.
Definition: what is uphill VMA?
Uphill VMA can be defined as the maximal uphill speed (or work rate) at which an athlete reaches (or closely approaches) VO₂max. It can be expressed as km/h at a given grade, as VAM (vertical meters per hour), or as a mechanical/power-equivalent metric.
In trail running, VAM is frequently more informative than horizontal speed because it directly reflects gravitational work. Still, uphill VMA and VAM are not strictly identical.
Uphill VMA vs VAM: close, but not the same
VAM (m/h) is an outcome: how much elevation you gain per hour at a given effort. Uphill VMA refers to maximal aerobic intensity in uphill conditions.
Two runners can be near VO₂max uphill but produce different VAM values due to differences in technique, relative strength, economy, and metabolic tolerance.
In practice: VAM over a 5–6 minute maximal uphill effort is often a strong field proxy for uphill VMA, but it remains a composite measure.
Key determinants of uphill VMA
Climbing highlights factors that may be secondary on flat terrain. Understanding them improves both test interpretation and training design.
VO₂max (and the ability to express it uphill)
VO₂max measured uphill or on an incline treadmill can differ from flat VO₂max. Some athletes express aerobic power more effectively uphill due to posture, coordination, and sustained ventilation despite higher local muscular strain.
Relative strength and local muscular endurance
Relative strength (strength-to-weight) is crucial uphill. At similar aerobic strain, a lighter or relatively stronger athlete can produce higher VAM. Local muscular endurance (repeated concentric force production) is also decisive.
Uphill movement economy
Economy depends on posture (slight forward lean, stable pelvis), cadence control, and arm-leg coordination. Inefficient technique increases oxygen demand and accelerates peripheral fatigue.
Anaerobic contribution and duration effects
Short tests (2–4 minutes) or very steep grades can inflate performance via anaerobic contribution. For a meaningful ‘aerobic’ indicator, duration and pacing stability matter as much as the final number.
How to measure uphill VMA in the field
A useful measurement must be repeatable: steady grade, sufficient duration to approach VO₂max, and stable pacing. The goal is not to sprint, but to sustain a maximal steady effort.
The 5–6 minute uphill test (recommended)
Pick a steady climb (8–15%), consistent surface, and perform a 5–6 minute maximal effort with controlled pacing (avoid an explosive start). Record horizontal distance, elevation gain, heart rate (if available), and RPE.
Then compute VAM: elevation gain (m) / time (h). Over 5–6 minutes, VAM becomes a strong anchor for prescribing uphill VO₂max sessions.
Alternative: 3-minute repeats (if needed)
If terrain constraints prevent longer climbs, 3-minute efforts can work, but anaerobic contribution rises. Prioritize repeatability (similar outputs across reps) over a single best performance.
Running power: use carefully
Running power can help track progress uphill, but absolute values vary across models and technique. Use it primarily as a personal benchmark on consistent segments.
Training with uphill VMA for trail and long races
The goal is not to stack hard sessions, but to target the specific energy system and muscular constraint you want to improve. Uphill VMA offers an intensity anchor, while training must stay aligned with long-race demands (durability).
Short uphill intervals (30 s to 1 min)
10–15% grade with full recovery. Goal: stimulate VO₂, power, and coordination without turning the session into pure anaerobic work.
- Example: 12 × 45 s uphill / 1’15–1’30 easy recovery
- Cue: hard but controlled; tough final reps without collapse
Long uphill intervals (3 to 6 min)
Moderate grade at near-VO₂max intensity. Goal: sustain high aerobic output and improve climbing capacity.
- Example: 5 × 4 min uphill / 3 min recovery
- Anchor: VAM close to your 5–6 min test (slightly lower for longer series)
Continuous climbing blocks (15 to 30 min)
Submaximal tempo/sweet-spot uphill. Goal: economy, muscular endurance, and direct transfer to long trail racing.
- Example: 2 × 20 min steady climb / 8–10 min recovery
- Focus: posture, steady cadence, controlled breathing
Uphill VMA, fatigue, and long races: the key variable
In long trail races, performance depends less on your maximum and more on the fraction of that maximum you can maintain after hours of running. That’s durability: limiting degradation in economy, strength, and sustainable intensity.
A runner with huge 6-minute VAM who collapses later will often be outperformed by a slightly less ‘powerful’ but more durable athlete. In racing, the best strategy is the one that protects late-race production.
Direct implications for trail pacing
Uphill VMA is most valuable to prevent pacing mistakes: going too hard on the first climb, overestimating your ability to surge, and paying for it mechanically (muscles) or metabolically (glycogen, digestion).
In practice, uphill pacing should be effort-based: breathing, RPE, heart rate (with limitations), plus VAM/time-on-climb anchors. The aim is durability—because the ‘second race’ often starts after halfway.
Conclusion: specificity and credibility
Uphill VMA is not a gimmick. It’s a trail-specific lens combining aerobic power, relative strength, movement economy, and muscular resilience. Flat VMA remains useful, but incomplete once terrain turns vertical.
The real improvement is not only climbing faster in a test—it’s becoming more efficient uphill and more durable over time. That’s the essence of smart pacing: optimize real effort, not a misleading pace number.
Go further with elevation-aware pacing
In trail running, effort matters more than speed. Use SmartPacer to turn a GPX profile into a realistic pacing plan—segment by segment—accounting for terrain and fatigue.
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