While threshold tests and power data can drive effective training, they don’t always explain performance plateaus or long-term shifts in capacity. That’s why more and more coaches are turning to physiological tools, like VO₂ max testing and DEXA scans.
Benefits of VO2 Max Testing and DEXA Scans
VO₂ max – maximal oxygen uptake in ml/kg/min – offers a high-level view of aerobic potential. While it’s less useful for day-to-day programming than lactate threshold or critical power, it can help identify declines in capacity, recovery issues, or genetic ceilings.
DEXA (dual-energy X-ray absorptiometry) scans go beyond body fat percentages by quantifying regional lean mass, bone density, and visceral fat. This data gives coaches and athletes insight into asymmetries, underfueling, or bone loss, especially in endurance athletes prone to low energy availability.
While not essential, VO2 max and DEXA scans can sharpen your coaching lens, offering insight you can’t get from training logs alone.
VO₂ Max: What It Shows
VO₂ max represents the maximal rate at which an athlete can take in and use oxygen during intense exercise. It’s governed by cardiac output, blood oxygen-carrying capacity, and muscle mitochondrial density. In endurance athletes, a high VO₂ max correlates strongly with performance, especially in events lasting over four minutes.
For coaches, VO₂ max serves best as a capacity marker. If an athlete’s VO₂ max has declined over time, it may suggest detraining, illness, or aging-related changes. On the flip side, if it’s stable while performance improves, you’re likely seeing gains in economy, lactate threshold, or durability.
VO₂ max also helps identify when an athlete is training close to their ceiling, which is useful when deciding whether to focus on volume, intensity, or efficiency.
Where VO₂ Max Falls Short
VO₂ max alone doesn’t determine race-day success. Two athletes with the same VO₂ max may have vastly different lactate thresholds, running economy, or fatigue resistance. VO₂ max also doesn’t explain how well an athlete is absorbing training load or recovering. That’s where longitudinal tracking and cross-referencing with performance data matter.
Real-World Example: After a winter of cross-training and lighter run volume, one athlete’s VO₂ max held steady in testing, but field data showed a drop in threshold pace. This divergence indicated a need for more running-specific stress and efficiency work, not necessarily more volume.
DEXA Scans: More Than Fat Percentage
DEXA (dual-energy X-ray absorptiometry) scans are often seen as a tool for measuring bone density, but their utility goes further for coaches. A full-body DEXA scan provides detailed maps of lean tissue distribution, fat mass, and even visceral fat estimates. This information is particularly valuable for endurance athletes who often operate on the edge of energy availability.
What a DEXA Scan Reveals
- Muscle asymmetries between limbs. This is especially useful post-injury.
- Lean mass loss. Often during heavy training blocks or after illness.
- Low bone mineral density, especially in females or masters athletes.
- Visceral fat accumulation despite low overall weight.
For athletes with a history of stress fractures, menstrual dysfunction, or RED-S risk factors, DEXA scans are one of the most reliable tools for confirming systemic impact. They can help benchmark body composition changes across seasons and training phases, even in healthy athletes.
Case In Point: Despite strong lab numbers, a lean, high-performing athlete with a history of endurance racing showed significant left-right lean mass discrepancy and low spinal bone density in a DEXA scan. The findings prompted a shift toward heavier strength training and targeted nutrition, which later showed measurable improvements in follow-up testing.
VO2 Max and DEXA Scans in Coaching
You don’t need VO₂ max or DEXA scan data to write a smart plan. But these tools can:
- Validate or challenge assumptions based on observational data.
- Guide macro-level planning, especially during transitions or rebuilds.
- Support individualized coaching for aging athletes or those prone to injury.
For instance, if an athlete’s VO₂ max is stable but the athlete is underperforming, it might be time to look at muscle mass, fueling, or training balance. If a DEXA scan shows declining lean mass, that may explain a drop in power or an uptick in injuries, and inform changes in strength programming or nutrition.
Scheduling these tests annually – or semi-annually during key transitions – can create a more complete picture of adaptation, resilience, and long-term potential. It also helps foster athlete buy-in through data they can see and track.
Final Thoughts
As coaches, we train what we can measure. VO₂ max and DEXA scans aren’t required to develop strong athletes, but they offer high-resolution insight into how the body responds to training stress. Used wisely, they support smarter decisions for performance, health, longevity, and the sustainability of sport.
