(11) A Smaller Winter Week Can Preserve Fitness Without Preserving Ultra Readiness

Decide what the smaller week must preserve

A reduced winter running schedule can preserve aerobic fitness for several weeks, but it cannot be assumed to preserve the durability needed for a long ultra. The useful decision is therefore which capacities to maintain while daylight, weather and family commitments restrict training. Treating every lost kilometre as a debt encourages hurried sessions; treating a stable watch estimate as complete readiness conceals a different problem.

This argument concerns healthy runners making a temporary scheduling adjustment. Illness, injury and persistent exhaustion require different decisions. Nor is maintenance a promise of improvement: the smaller programme has a limited job, with a planned point at which normal preparation resumes.

Reduce the dose without confusing the experiments

Spiering and colleagues' review found that general populations could retain endurance adaptations with substantial reductions in training frequency or duration, provided intensity was maintained. It explicitly found insufficient evidence to prescribe equivalent minimums for athletes. The often-repeated headline of two sessions a week therefore needs its original context. [1]

Hickson and Rosenkoetter studied 12 young adults after ten weeks of training. Reducing frequency from six days to two or four maintained maximal oxygen uptake over the following 15 weeks; session duration and intensity stayed unchanged. A separate duration experiment preserved maximal oxygen uptake with 13-minute sessions, but endurance lasting roughly two hours deteriorated in that shortest-duration group. Those results cannot be combined into a tested prescription of two 13-minute runs. [2–3]

A further Hickson experiment reduced intensity while retaining frequency and duration, and aerobic gains were not fully preserved. In runners, Houmard maintained five-kilometre performance during three weeks of sharply reduced mileage, while Skovgaard improved ten-kilometre performance with reduced volume and demanding speed-endurance work. Neither establishes that unfamiliar maximal efforts belong in an interrupted winter week. Preserve an accustomed stimulus; do not invent a harder one to compensate. [4–6]

A short reduction differs from stopping

Mujika and Padilla's reviews, Neufer's synthesis and Coyle's detraining experiments explain why some continuing activity matters. Complete cessation can reduce blood volume and alter the metabolic response to a previously familiar workload. The timing and size of losses depend on what is measured and who was trained. Zheng's meta-analysis and Barbieri's later review reinforce that distinction between partial reduction and stopping altogether. [7–13]

The strongest counterargument is that less training can improve performance. It can: Wang's tapering meta-analysis, Mujika's taper guidance and Shepley's experiment show why reducing accumulated fatigue before competition may help. But a taper is a short intervention after substantial preparation. Its benefits do not demonstrate that a low-volume winter preserves every adaptation indefinitely. [14–16]

That is a reason to set an end date for the maintenance block. Without one, a temporary compromise can become the programme while the spring race remains unchanged.

Keep a separate account of durability

Zanini compared performance-matched male runners who regularly completed long runs with runners whose sessions were shorter. Running economy deteriorated less across 90 minutes in the long-run group. This was an association, with training volume also differing; it cannot establish a mandatory weekly distance. It does show why similar fresh performance can coexist with different responses to prolonged exercise. [17]

Nuuttila found that lactate-threshold speed fell after 90 minutes of easy running in recreational runners. Hunter's methodological review and Zanini's economy research also show that durability depends on the test, intensity and athlete. Lloria-Varella found terrain-specific deterioration in trail runners despite unchanged measured locomotion cost. There is no single fitness score that resolves these differences. [18–21]

Strength training offers another possible contribution: Zanini's randomised trial improved late-run economy after ten weeks. That supports retaining useful strength work, without treating it as a substitute for progressive time on feet. The same specificity problem appears in our discussion of polarised training for mountain ultras. [22]

Build a week that can survive winter

Minimal-dose resistance research offers practical options when gym time also shrinks. Fyfe reviews brief approaches; Tavares found reduced frequencies maintained strength and muscle size in previously untrained men. Walker's older women maintained strength while losing initial muscle-size gains with once-weekly training. Again, the outcome and population matter. [23–25]

My coaching inference is to protect repeatable appointments first: retain manageable easy running, a familiar quality stimulus when healthy and recovered, and established strength work. Keep a longer outing when circumstances allow, without forcing it onto unsafe ground. Shorten the session before making it an exhausting replacement for several missed runs.

When normal training resumes, assess comfortable duration and terrain tolerance separately from fresh pace. Use the running progression framework to rebuild what the reduced block stopped rehearsing. Put the first longer run back into the diary at a duration you can currently manage, rather than the duration printed in last month's plan.

Sources

Reduced training experiments

1. Spiering BA et al., "Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time" https://pubmed.ncbi.nlm.nih.gov/33629972/

2. Hickson RC et al., "Reduced training frequencies and maintenance of increased aerobic power" https://pubmed.ncbi.nlm.nih.gov/7219129/

3. Hickson RC et al., "Reduced training duration effects on aerobic power, endurance, and cardiac growth" https://pubmed.ncbi.nlm.nih.gov/6214534/

4. Hickson RC et al., "Reduced training intensities and loss of aerobic power, endurance, and cardiac growth" https://pubmed.ncbi.nlm.nih.gov/3156841/

5. Houmard JA et al., "Reduced training maintains performance in distance runners" https://pubmed.ncbi.nlm.nih.gov/2318562/

6. Skovgaard C et al., "Effect of speed endurance training and reduced training volume on running economy and single muscle fiber adaptations in trained runners" https://pubmed.ncbi.nlm.nih.gov/29417745/

Detraining and tapering

7. Mujika I et al., "Detraining: loss of training-induced physiological and performance adaptations. Part I: short term insufficient training stimulus" https://pubmed.ncbi.nlm.nih.gov/10966148/

8. Mujika I et al., "Detraining: loss of training-induced physiological and performance adaptations. Part II: Long term insufficient training stimulus" https://pubmed.ncbi.nlm.nih.gov/10999420/

9. Neufer PD, "The effect of detraining and reduced training on the physiological adaptations to aerobic exercise training" https://pubmed.ncbi.nlm.nih.gov/2692122/

10. Coyle EF et al., "Effects of detraining on responses to submaximal exercise" https://pubmed.ncbi.nlm.nih.gov/3902770/

11. Coyle EF et al., "Effects of detraining on cardiovascular responses to exercise: role of blood volume" https://pubmed.ncbi.nlm.nih.gov/3944049/

12. Zheng J et al., "Effects of Short- and Long-Term Detraining on Maximal Oxygen Uptake in Athletes: A Systematic Review and Meta-Analysis" https://pubmed.ncbi.nlm.nih.gov/36017396/

13. Barbieri A et al., "Cardiorespiratory and metabolic consequences of detraining in endurance athletes" https://pubmed.ncbi.nlm.nih.gov/38344385/

14. Wang Z et al., "Effects of tapering on performance in endurance athletes: A systematic review and meta-analysis" https://pubmed.ncbi.nlm.nih.gov/37163550/

15. Mujika I et al., "Scientific bases for precompetition tapering strategies" https://pubmed.ncbi.nlm.nih.gov/12840640/

16. Shepley B et al., "Physiological effects of tapering in highly trained athletes" https://pubmed.ncbi.nlm.nih.gov/1559951/

Durability and the limits of transfer

17. Zanini M et al., "Regular Long Runs and Higher Training Volumes Are Associated with Better Running Economy Durability in Performance Matched Well-Trained Male Runners" https://pubmed.ncbi.nlm.nih.gov/40878015/

18. Nuuttila OP et al., "Durability in recreational runners: effects of 90-min low-intensity exercise on the running speed at the lactate threshold" https://pubmed.ncbi.nlm.nih.gov/39384626/

19. Hunter B et al., "Durability as an index of endurance exercise performance: Methodological considerations" https://pubmed.ncbi.nlm.nih.gov/40150840/

20. Zanini M et al., "Durability of Running Economy: Differences between Quantification Methods and Performance Status in Male Runners" https://pubmed.ncbi.nlm.nih.gov/38857519/

21. Lloria-Varella J et al., "Assessing Physiological Durability in Trail Runners: Terrain-Specific Responses to a 90-Minute Submaximal Run" https://pubmed.ncbi.nlm.nih.gov/41130463/

22. Zanini M et al., "Strength Training Improves Running Economy Durability and Fatigued High-Intensity Performance in Well-Trained Male Runners: A Randomized Control Trial" https://pubmed.ncbi.nlm.nih.gov/40016936/

Maintaining strength

23. Fyfe JJ et al., "Minimal-Dose Resistance Training for Improving Muscle Mass, Strength, and Function: A Narrative Review of Current Evidence and Practical Considerations" https://pubmed.ncbi.nlm.nih.gov/34822137/

24. Walker S et al., "Maximum Dynamic Lower-Limb Strength Was Maintained During 24-Week Reduced Training Frequency in Previously Sedentary Older Women" https://pubmed.ncbi.nlm.nih.gov/29570597/

25. Tavares LD et al., "Effects of different strength training frequencies during reduced training period on strength and muscle cross-sectional area" https://pubmed.ncbi.nlm.nih.gov/28316261/