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Summary

The athlete has shown excellent physical development over a ~7 week period (August to October). The Norwegian Professional Cross Country Skier was tested at a Norwegian Exercise Physiology Lab  8/12/2025 & 8/13/2025.

The most significant improvements are seen in his efficiency and his performance at lactate threshold intensities.

He became significantly fitter, with a substantial increase in his power-to-weight ratio (ml/kg/min). His maximal performance (VO2max) also improved in classic skiing.

The combined effect of a higher VO2max and greatly improved efficiency means that the athlete’s race pace is now faster, and he can sustain it for longer.

The athlete used 1 tablespoon of Stamox between the tests.

Key Findings

The athlete produces substantially less lactate at the same or even higher workloads. This means his body has adapted to use oxygen more efficiently and clear lactate better, allowing him to ski faster before fatigue sets in.

His VO2max also increased:

  • Classic Diagonal: 74.0 → 76.6
  • Skating Double-Double: 71.1 → 75.4

This is a clear indicator of enhanced cardiovascular fitness.
Results and Progression by Test Type

1. Classic Skiing (Klassisk)

This test measures performance in the diagonal stride (uphill) and double poling (flat) techniques.

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1. Conclusion for Classic Skiing (Klassisk)

Excellent progress. The athlete is significantly more efficient in the diagonal technique after the training period. He has a higher power-to-weight ratio (ml/kg/min) and can maintain higher speeds with less physiological strain.

Change & Analysis 

VO₂max: A significant improvement due to increased fitness and lower weight. The lower weight is a major factor in improved efficiency.

Key Progression Indicator: Performance at Submaximal Intensities

At a similar speed (e.g., 11.0 km/h), his lactate was 2.88 mmol/L in August but only 2.33 mmol/L in October. He is now producing less lactate at the same workload, meaning his body is more efficient. He could sustain a higher speed (11.5 km/h) at a lower lactate level in October (3.49 mmol/L) compared to August (4.07 mmol/L at the same speed). His lactate threshold has clearly shifted to the right, indicating better endurance capacity.
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Results and Progression by Test Type

2. Skating (Skøyting)

This test measures performance in double-double (flat/gentle incline) and paddle (steep incline) skating techniques.

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2. Conclusion for Skating (Skøyting)

Outstanding progress. The athlete has improved his absolute VO2max in the double-double technique and his efficiency across all submaximal intensities in skating. His body is far more economical at high speeds.

Change & Analysis 

VO₂max: (+6.0%). A very strong improvement.

Key Progression Indicator: Performance at Submaximal Intensities

The submaximal intervals show a similar trend. For example, at 15.5 km/h, his lactate was 1.70 mmol/L in August but only 1.32 mmol/L in October at a higher speed of 16.3 km/h. This is a dramatic improvement in efficiency. He is now much faster at a lower physiological cost.
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Overall Conclusion and Progression Summary

The test data confirms that the athlete shows a definitive and impressive progress across all major physiological markers for a cross-country skier.

1. Improved Body Composition

The athlete had a reduction in body weight by approximately 3.1 kg,   which directly enhances his power-to-weight ratio, a critical factor in endurance sports like cross-country skiing.

2. Significant Gain in Metabolic Efficiency:

This is the most notable finding. In both classic and skating techniques, the athlete produces substantially less lactate at the same or even higher workloads. This means his body has adapted to use oxygen more efficiently and clear lactate better, allowing him to ski faster before fatigue sets in.

3. Increased Maximal Power (VO2max)

His maximal aerobic power relative to his weight (ml/kg/min) improved in all key areas:

  • Classic Diagonal: 74.0 → 76.6
  • Skating Double-Double: 71.1 → 75.4

This is a clear indicator of enhanced cardiovascular fitness.

4. Enhanced Performance Capacity

The combined effect of a higher VO2max and greatly improved efficiency means that the athlete’s race pace is now faster, and he can sustain it for longer. His "engine" is both more powerful and more fuel-efficient.

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Note

The data shown alone cannot prove causation as that would require randomised, controlled studies with a placebo etc. But the pattern in the data (improved efficiency and increased maximum capacity) is highly consistent with the scientifically documented effect of nitrate supplementation in endurance athletes. It is the combination of the results that is interesting: Increased VO₂max and improved lactate profile showing his increase in efficiency over a short period (7 weeks).

Dr. Nils P. Reither

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