Executive Summary

• You are a well-trained 43-year-old endurance athlete with a healthy body mass and substantial multisport background.
• Cycling VO2max was 38.1 mL/kg/min, placing you in the good range for women aged 40–49. This provides a solid aerobic base, but is below the level commonly seen in athletes competing for a half-Ironman age-group win.
• Your breathing capacity appears strong: peak ventilation was 105.2 L/min, with deep breaths rather than inefficient rapid, shallow breathing. There is no evidence that lung function is the main restriction.
• VT1 occurred at 114 W and 146 bpm, while VT2 occurred around 141–150 W and 167–170 bpm. You can sustain a relatively high fraction of your maximum capacity, indicating good tolerance of hard work.
• The clearest opportunity is to raise cycling power at easy endurance effort, race effort, and threshold, while protecting run durability and recovery. The existing training focus appropriately targets these areas.

❗ Your cycling power landmarks are relatively low for an athlete aiming to win her half-Ironman age category: approximately 1.9 W/kg at VT1 and 2.4–2.5 W/kg near VT2. This is a performance finding, not a health concern, and may partly reflect test protocol, current fatigue, equipment calibration, or cycling-specific fitness. Repeat testing after the focused bike block using the same protocol; confirm thresholds if possible.

Limiting Factor

Cardio-muscular aerobic capacity is the primary limiter (beta function).

Your lungs appear capable of moving enough air, but your overall aerobic ceiling and cycling power ceiling are modest relative to your competitive goal: VO2max was 38.1 mL/kg/min and peak cycling power was 165 W, or about 2.8 W/kg. Your relatively high VT2 position suggests that you use a good proportion of your available capacity, so the greater gain is likely to come from improving oxygen delivery and muscle use of oxygen rather than simply improving tolerance of discomfort.

Coach-Ready Takeaway

Maintain the planned high proportion of easy work, then improve cycling-specific endurance, race power, and VO2max with well-spaced key bike sessions while prioritising fueling, recovery, and run durability.

Training focus for the next 2–3 months

The main priority is to raise cycling-specific aerobic power: particularly power at VT1, race power, and power near VT2, while maintaining the run durability needed to execute a strong half-Ironman run. Your threshold tolerance is relatively well developed, but the overall aerobic ceiling and cycling power ceiling are the clearest opportunities for improvement.

The most productive approach is not simply adding more hard training. Maintain a high proportion of low-intensity volume, then place one race-specific tempo/threshold bike session and one VO2max-oriented session each week, provided recovery remains good. This should improve cardiac output, muscular oxygen use, and sustainable bike power without compromising the run.

For half-Ironman preparation, develop the ability to ride efficiently around 120–132 W, generally with HR around 150–160 bpm under moderate conditions. This should feel controlled rather than like a threshold effort. The goal is to arrive at the run with stable fueling, manageable cardiac drift, and preserved leg function.

Weekly structure

With six training sessions per week, keep approximately 80% of total weekly training time below VT1: below 114 W and below 146 bpm on the bike. Use power as the primary cycling guide and HR as a check for fatigue, heat stress, hydration, and accumulated load.

A practical six-session structure could include:

• One long aerobic ride, progressing toward 2.5–4 hours, mostly at 90–110 W and below 146 bpm.
• One race-specific bike session at 125–140 W.
• One VO2max or VT2-focused bike session.
• One brick run after the long ride or race-specific ride.
• One long easy run and one swim session, or two swim sessions if swimming volume is currently a limiting discipline.
• Include two short strength sessions weekly where possible, ideally after easy training or as 20–35 minute standalone sessions. These can replace, rather than add to, low-value extra intensity.

Avoid stacking hard bike intervals, hard running, and long bricks on consecutive days. Allow at least 48 hours between major high-intensity sessions.

Session examples

1. Race-specific tempo and bike durability
2. 2 × 20 minutes at 130–140 W, with 8–10 minutes very easy spinning between intervals.
3. HR should generally settle around 155–165 bpm, remaining below VT2 where possible.
4. Progress only when power is stable and HR drift is modest.

5. Finish with a 20–40 minute easy brick run, keeping the run conversational.

6. VT2 development

7. 4 × 8 minutes at 145–155 W with 6–8 minutes easy recovery.
8. HR may rise toward 165–172 bpm by the final repetitions.
9. Keep cadence smooth and avoid surging above target power.

10. Use this session every 7–10 days if recovery is limited, or weekly during a focused bike block.

11. VO2max development

12. 5 × 4 minutes at 155–170 W with 4 minutes easy spinning.
13. HR should rise into approximately 170–178 bpm during later intervals; do not chase HR early in each repetition.
14. Start with four repetitions if needed and progress to six only if power, technique, and recovery remain strong.

15. Do not combine this with a hard run interval session in the same 48-hour period.

16. Long aerobic ride

17. 2.5–4 hours primarily at 90–110 W, below 146 bpm.
18. In the final hour, include 2–3 × 12–15 minutes at 120–132 W if fatigue is controlled.
19. Practice race fueling at 60–90 g carbohydrate per hour, with fluid and sodium adjusted to weather and sweat rate.

Progression over 2–3 months

For the first 4–6 weeks, prioritize consistency and controlled execution. Build the long ride gradually, increase race-specific interval volume, and establish reliable fueling. For example, progress from 2 × 20 minutes to 3 × 20 minutes at 130–140 W, or from 4 × 8 minutes to 5 × 8 minutes at 145–155 W.

After 4–6 weeks, if easy-session HR is stable and fatigue is well managed, shift slightly toward more race specificity:

• Add longer continuous blocks of 30–45 minutes at 120–132 W during long rides.
• Progress bricks toward 40–60 minutes of easy-to-steady running, not a hard run off a hard bike every week.
• Maintain one VO2max session weekly or every 7–10 days, rather than increasing both VO2max and threshold volume simultaneously.
• Every third or fourth week, reduce total training load by approximately 20–30%, while retaining a small amount of intensity.

Recovery, health constraints, and what to avoid

At 59 kg and a BMI of 20.7, body-mass reduction is not a priority. Low energy availability would be more likely to impair adaptation, bone health, hormonal health, immune function, and recovery than to improve performance. Fuel hard and long sessions adequately, consume protein consistently across the day, and ensure carbohydrate intake rises with training load.

Pay particular attention to iron status, ferritin, vitamin D, menstrual or menopausal symptoms, sleep quality, and persistent fatigue. Seek medical review if there is unusual breathlessness, declining performance despite training, recurrent illness, changes in menstrual function, or prolonged exhaustion.

Reduce intensity when easy-ride HR is 5–8 bpm higher than normal at 100–110 W, legs remain heavy for more than 48 hours, sleep declines, or power is falling at a given perceived effort. Avoid frequent “moderately hard” riding between 115–140 W without a clear purpose; this can create fatigue without providing the quality of either true endurance or structured threshold work.

Follow-up

Repeat the metabolic test in 2–3 months using the same cycling protocol. The key markers of progress will be higher power at VT1 and VT2, improved VO2max, lower HR at endurance power, and the ability to sustain half-Ironman race power with less cardiac drift.