[CoachCorner] How I Prescribe Training: Periodization and Training Phases
Long term training structure for endurance athletes
CoachCorner is a series of blogs in which I share information that is mostly relevant to the runners I coach. Regardless, feel free to comment below should you have any questions, and I will follow up. Thank you.
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When we start working together, I will provide you with a long-term training plan, ideally covering more than 6 months, until your main race of the year. This training plan will be a high level view of what we are going to focus on and will structure your training up to the microcycle level (i.e. 1-3 week training cycles).
The training plan is an overview of your training periodization designed based on your goals, training history, and current limiters. It will be structured in training phases (Base, Support, Specific, Taper, Transition), which I describe in detail in this blog. The plan will then be accompanied by a detailed training prescription and individual training days and Types, every 3-4 weeks (as these cannot be planned too far in the future, and will likely change based on unexpected events, your own response to training, etc.), using the structure I covered in detail here.
The exact set of Training Types making up a microcycle and Training Phase will depend also on the type of periodization used, e.g. non-linear or block (discussed below).
Here is a visual representation as an example:
In practical terms, you will receive a document with an overview of your training phases and periodization, while the microcycle and training types will be provided via third-party software (e.g. TrainingPeaks).
Training Periodization
Training periodization refers to the systematic planning of training cycles, with the goal of optimizing performance for a specific event. This approach divides the training year into distinct phases, each with a specific focus, such as building aerobic endurance (what I call Base) or refining race-specific skills (what I call Specific). These phases are structured to progressively overload the body while incorporating recovery periods to prevent overtraining and ensure adaptation.
Ideally, your response will be monitored using measurements of resting physiology and a subjective questionnaire, e.g. using HRV4Training. This is however not a requirement.
The Training Phases detailed below will be used for your training plan regardless of the exact periodization strategy that we will end up employing. Typically, I prescribe either non-linear periodization or block periodization, depending on the athlete history, level and preference. Block periodization includes several workouts that aim at stressing one specific system or training type, e.g. predominantly threshold workouts, during a microcycle. In contrast, non-linear periodization alternates between different types of training within a shorter timeframe, such as alternating through VO2max, threshold, etc. within a microcycle. While well-trained athletes tend to benefit more from block periodization (i.e. a more dense period focusing on a single stimulus), other considerations might apply (e.g. if injury risk is high, we might opt for non-linear periodization and less dense focus).
Both periodization approaches might include the same high level structure and phases (e.g. a Base phase for aerobic development or a Specific phase for race-specific preparation), but they vary in how Training Types are distributed daily or weekly.
Microcycles
A microcycle is the smallest structural unit in a running training plan, typically spanning 1–3 weeks. It consists of a carefully planned sequence of workouts and other training or rest days aimed at achieving specific short-term goals while contributing to the broader objectives of a training phase.
Microcycles provide a practical framework to organize training stress and recovery, ensuring athletes can handle the workload while progressing toward their targets. A microcycle is where the day-to-day and week-to-week training dynamics are refined, allowing athletes to repeat key workouts and progressively adapt to a stimulus.
While the 1-week microcycle is often used for practical reasons, we might want to extend the microcycle to 2 or 3 weeks, depending on the athlete's history and goals. For example, for my own training, I am currently experimenting with a 3-week microcycle with non-linear periodization, so that I can routinely touch on different stimuli to address my specific limiters (e.g. one VO2max, one threshold, and one long Endurance run over two weeks, plus a third week of z2 focus, to help tackle issues with running economy at ultra race pace or near marathon pace). Over different training phases (e.g. from Base to Specific) the exact workouts and focus will change, but the basic 3-week structure will remain. This is what the microcycle is about, in the plans I prescribe.
The short duration of a microcycle offers flexibility to adjust training based on the athlete's response, and cannot be lied out entirely too soon (which is why premade training plans are a poor choice). Thus, I will plan your detailed training only 3-4 weeks in the future, typically.
Training Phases
Now that we have seen a high level view of peridization and what a microcycle is, below are the training phases I normally use to build training plans. Similarly to the training types blog, the aim here is to define a common language so that training can be carried out as originally prescribed.
In any structured training plan, the phases are designed to build upon one another, targeting different aspects of fitness and gradually preparing the athlete for peak performance in their goal race. For endurance athletes aiming at racing long distances (marathons or ultramarathon) the process normally starts with a focus on general aerobic fitness and moves towards event-specificity in terms of intensity, environmental conditions, etc. Each phase has a specific purpose and progression, ensuring that training stress is balanced with recovery.
Personally, I use the following phases, which are detailed below:
Base: generic phase focusing on aerobic fitness, often including neuromuscular training and top-end speed or VO2max development work.
Support: in between Base and Specific, this phase aims at further developing key skills to improve race performance, depending on the athlete's goals and limiters.
Specific: race-specific phase focusing on the demands of the race (e.g. pace, elevation, environmental conditions, etc.). Here we will also focus more on race nutrition.
Taper: a very short phase aiming at gaining freshness for the race.
Transition: post-race, less structured activity.
1. Base Phase
The foundation of ultramarathon training, this phase focuses on building aerobic capacity and developing fatigue resistance through consistent training. Key adaptations include increased mitochondrial density, capillarization, and improved slow-twitch muscle fiber efficiency. Workouts are predominantly easy to moderate intensity (Zone 1–2) to stimulate aerobic metabolism while minimizing injury risk.
This is also a good time of the year to work on the athlete’s weaknesses. For ultramarathoners, high-intensity work that is not specific to race demands might also be included (e.g. VO2max), together with neuromuscular training (e.g. hill sprints, strides), to improve running economy.
Key Components:
Progression: Gradually increase weekly mileage while maintaining consistency. Avoid rapid increases in volume or intensity. Allow time for tissue adaptations and maintain a balance between load and recovery. Long runs are typically at very low intensity (e.g. RPE 1-2, Zone 1).
Typical Workouts: Introduce strides (e.g. 60–100m sprints) and hill sprints (e.g. 8-10” with long recoveries) 2–3 times weekly to improve elastic energy utilization, neural activation, and muscle-tendon stiffness, which will contribute to improved running economy. Include occasional short intervals for well-trained athletes, as these are less emphasized later in the specific phase.
Benefits: Increased fat oxidation, improved efficiency of slow-twitch muscle fibers, and overall cardiovascular development.
2. Support Phase
This phase bridges the Base phase and Specific race preparation, focusing on enhancing muscular endurance and fuel utilization. Training includes moderate intensity and threshold efforts to improve metabolism and fatigue resistance.
This phase introduces more specific work, targeting the athlete’s aerobic and anaerobic thresholds. Training at or near the first and second thresholds (High-end zone 2, Zones 3, and 4) helps improve lactate clearance and utilization, allowing the athlete to sustain higher intensities for longer periods.
Key Components:
Progression: Here we might favor intensity over very long runs, therefore slightly reducing overall volume. Long runs, while shorter, might include intensity (e.g. threshold or tempo segments) and will be harder (e.g. RPE 4-6, Zones 2 and 3).
Typical Workouts: Tempo runs, steady-state efforts at marathon pace, and threshold intervals (e.g., 10-20 minutes with short recoveries). Continue strides or hill sprints weekly, ensuring tendons and muscles remain primed for harder work.
Benefits: Raise lactate thresholds and improve the ability to sustain prolonged efforts at moderate to high intensities. Improved carbohydrate utilization, buffering capacity, and fatigue resistance.
3. Specific Phase
This phase replicates the demands of the race, focusing on pace, terrain, and environmental factors. The goal is to prepare the body for race-day conditions, including muscular fatigue, fueling strategies, and mental endurance.
The focus is on maintaining the fitness gains from previous phases while fine-tuning pacing and strategy. It’s about efficiency, economy, planning and executing, more than gaining additional fitness.
Key Components:
Progression: Workouts might be very demanding in this phase, as they tend to be both hard and long, and therefore might require longer recovery and fewer extra workouts in the microcycle. The goal here is to be race-ready (e.g. more economical or heat-adapted) more than to gain fitness. Intensity varies (mix of Zones 3-5, depending on the race). Ideally, terrain and fueling strategies should also be tried out and tested.
Typical Workouts: Long runs at marathon pace, progression runs, and race simulations.
Benefits: Prepare the athlete both mentally and physically for race day by mimicking event-specific conditions. Optimized pacing, improved mental readiness, and fine-tuned endurance / economy.
4. Taper Phase
The taper phase reduces training volume while maintaining intensity and specificity to allow full recovery and peak performance on race day. The focus is on gaining freshness, recovering glycogen stores, and sharpening mental readiness.
Key Components:
Progression: Decrease mileage by 30–50% compared to peak weeks, maintaining frequency but shortening runs. Perform shorter runs at race pace to maintain efficiency without overloading the body.
Typical Workouts: Shorter runs with strides or short intervals, focusing on recovery and maintaining rhythm. Might include short intervals and relatively short sessions at race pace.
Benefits: Reduced fatigue, improved freshness, and peak performance readiness. Building confidence by focusing on visualization and planning race-day strategy.
5. Transition
In the transition phase, we allow the body and mind to fully recover from the rigors of training and racing, while addressing any weaknesses, maintaining a light aerobic base, and setting the stage for the next training cycle. A good time of the year for non-running training, if that’s something you like doing.
Example
Below is an example of my preparation for the 100 km del Passatore this year, where you can see the 3-week microcycle, different training phases, and the specific focus on Training Types changing as we get closer to the race.
Based on this overview, I will build a detailed plan for each microcycle (via TrainingPeaks), with the required adjustments depending on your individual response.
Individual variability and flexible periodization
Needless to say, the above is a broad overview but each phase will be tailored to your specific goals, history, and fitness level. For example, a highly trained athlete might require less time in the Base Phase and focus more on specific race demands, while a less experienced athlete would need more time building aerobic capacity. Likewise, the balance of Zone 1 and Zone 2 training might vary depending on your aerobic threshold and fitness level (the fitter we get, the more demanding it becomes to train in Zone 2).
Training is not a one-size-fits-all approach. It’s a constantly evolving process that must be adapted to how your body responds. This is why I place importance on ongoing feedback and communication. Together, we’ll adjust the plan as needed to ensure you’re always moving toward your goals.
As you might have noticed, there is no mention in this blog of load or de-load weeks, or standard “2-3 weeks hard, 1 week easy” type of periodization. Personally, I prefer to make sure athletes stay healthy and have enough recovery time during each week, monitoring possible issues along the way, and staying flexible in terms of load management. Recovery is always part of the picture, not only every three weeks. Additionally, technology can help us make meaningful adjustments. If you are interested in tracking some of these aspects objectively, we can rely on the tools I have built - such as HRV4Training - to keep track of your body’s response via changes in resting physiology and adjust your training accordingly. Happy to discuss this further on an individual basis.
In your training plan you will typically find training days prefixed by the following structure:
[PHASE:MIC:WEEK:TRAININGTYPE] WORKOUT
Where PHASE is the training phase as discussed in this blog (e.g. Base, Specific, etc.). MIC is the microcycle in the current phase, only present for athletes using a 2 or 3-week microcycle instead of a 1-week microcycle. WEEK is the week number in the current microcycle and TRAININGTYPE is the training type as per this other blog post (e.g. recovery, tempo, etc.). After this prefix, you will find a detailed description of the workout. Here are a few examples:
[BASE:M1:W1:ENDURANCE] 60’ high-end Z2, just below the aerobic threshold
[BASE:M1:W1:EASY] 60’ easy, RPE 2
[SPECIFIC:M1:W1:TEMPO] 20’ warmup, 3 x 20’ tempo (RPE 7), 2’ recovery, 10’ cooldown
Once again, while we could spend our entire lives discussing phases, zones, thresholds, etc. - this is not the point of this blog, which simply aims to define a common language so that training can be carried out as originally prescribed when working together.
In case of any doubts, drop me a line.
Marco holds a PhD cum laude in applied machine learning, a M.Sc. cum laude in computer science engineering, and a M.Sc. cum laude in human movement sciences and high-performance coaching.
He has published more than 50 papers and patents at the intersection between physiology, health, technology, and human performance.
He is co-founder of HRV4Training, advisor at Oura, guest lecturer at VU Amsterdam, and editor for IEEE Pervasive Computing Magazine. He loves running.
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Thanks for this new series. I really like how you call the after race period "transition" and the fact you actually cover it part of your plan. I see many many plans stopping at the race day and people are just on their own to figure out what's next. Sometime you can find "recup" plans that one can stick next to a full marathon plan for example but this is not optimal either because a default plan would not know the approach taken on your main race plan. I also like you call it transition because most runners would have next goal in mind so for me a successful race is also an execution that allows you to move into regeneration phase and then without injuries allowing to start another base phase. And at the moment I've not found other long term metrics than HRV to actually see the effect of the different phases on body.