by smartrunningcoach | Oct 13, 2026 | Uncategorized
Most runners do not need to test their fitness every week. Test when enough training has passed for a meaningful change to be possible and when the result could actually change your training. Repeating hard tests too often can add fatigue while giving you very little new information.
It is easy to want constant proof that training is working. A good week makes you curious about how much faster you are. A bad week makes you worry that fitness has disappeared. Neither feeling is a strong reason to schedule another hard test.
A useful fitness test should answer a specific question. Has your fitness changed enough that training paces may need updating? Have you completed a meaningful training block and want to measure the response? Are you returning from a break and trying to establish a realistic starting point?
If the only trigger is one poor session, testing is usually premature. As we explain in Should One Bad Run Change Your Marathon Plan? short-term performance can vary for many reasons. A hard test performed while tired may tell you more about your fatigue than your underlying fitness.
There is no single testing interval that is perfect for every runner. The right timing depends on the athlete, the phase of training, the test being used and whether the result will change what happens next. The important principle is to allow enough training between tests for adaptation to occur.
Consistency is important. Use the same protocol where possible. Run on a similar surface, avoid unnecessary stops and compare results collected in reasonably similar conditions. A cool track test and a hilly test in extreme heat are not directly equivalent, even if the distance is the same.
Recovery before testing is vital too. A heavy training block, several poor nights of sleep or unusual soreness can suppress performance. If you are clearly not recovered, forcing a test can produce a misleading result and add another hard session to an already tired week.
The same logic used when deciding whether to replace a hard run with an easy run applies here. A fitness test is only useful when you are in a reasonable state to perform it.
You do not always need a race to measure fitness. Repeatable field tests can provide useful information between events. What counts is that the protocol suits the fitness marker you are trying to estimate and that you perform it consistently enough for the comparison to mean something.
Between tests, normal training still tells you a great deal. You can look at how easy pace feels, whether key sessions are becoming more controlled, how your long runs are progressing and whether you are recovering more reliably from week to week.
That is why marathon readiness should be viewed as a moving assessment rather than a single test score. Formal testing sharpens the picture, but it should sit alongside the rest of your training data.
A sensible rule is to test when the result is likely to change a decision. If nothing in your training would change regardless of the outcome, you probably do not need another test yet. Train, recover, give the adaptation time to happen and test again when the information will be useful.
by smartrunningcoach | Oct 13, 2026 | Uncategorized
Critical Speed is a modelled running speed that estimates the maximal metabolic steady state: the highest intensity at which the body can remain close to a physiological steady state for a prolonged period. Above Critical Speed, fatigue-related disturbances accumulate more quickly, and the time you can sustain the effort becomes limited.
The term sounds technical, but the idea is straightforward. The faster you run, the less time you can sustain that speed. By using maximal performances over different distances or durations, you can model the relationship between distance and time and estimate the speed that sits at the boundary between more sustainable and rapidly fatiguing exercise.
Critical Speed is not simply your 5K pace, 10K pace, threshold pace or marathon pace. It is calculated from more than one performance, which is useful because any single race or test can be influenced by pacing, weather, terrain, fatigue and execution.
The exact testing and modelling method is important. A 2026 scoping review of Critical Speed in running found that there is still no single agreed best protocol for measuring Critical Speed and D′. That is a useful reminder not to treat one calculation method as universally correct.
Critical Speed is often discussed with a second value called D-prime, written D′. D′ represents a finite distance capacity available above Critical Speed. In practical terms, it helps describe how much work a runner can do above that boundary before exhaustion.
You do not need to understand the mathematics to see the coaching value. Multiple performances can give a more complete picture of current running fitness than one race result alone. That is one reason a single unusually good or bad run should be treated as information rather than a final verdict on your fitness.
For field testing, the performances need to be hard enough to represent what you can actually do and different enough in duration to define the relationship properly. SmartRunning uses a sequence of tests to capture performance across different distances rather than relying on one result.
That information can then help individualise training intensity. Two runners with the same marathon goal do not necessarily have the same current fitness, the same strengths or the same appropriate training paces. Goal pace tells you where you want to go. Current fitness helps determine where training should start.
This fits with the way we think about marathon readiness. Readiness is not a single pass-or-fail test. It is an ongoing assessment of whether your training is moving in the right direction for race day.
Critical Speed should not be treated as a magic number. Training history, recent workload, recovery, injury status and the way you are responding to sessions still matter. Training load also changes the meaning of any pace because the same workout can create very different demands depending on what came before it.
The useful part of Critical Speed is not having another number on your watch. It is having a repeatable way to estimate current performance capacity, compare meaningful changes over time and use those changes to make training decisions that are more specific to the runner.
by smartrunningcoach | Oct 13, 2026 | Uncategorized
If you are training consistently but not getting faster, the answer is not automatically to run more. Progress can stall when training becomes too repetitive, hard sessions are packed too closely together, recovery is poor, or your training no longer matches your current fitness. First work out whether you have truly plateaued or whether short-term fatigue is hiding your fitness.
Running progress is rarely linear. A disappointing race, time trial or workout does not prove that your training has stopped working. Day-to-day performance moves around, especially when fatigue, sleep, stress, weather or pacing are different.
Before changing everything, remember that one bad run should not automatically change your marathon plan. A plateau is a pattern over time, not one session that went badly.
If the pattern has lasted for several weeks, start with consistency. Fitness improves when your body receives repeated training stimuli and enough recovery to adapt to them. A heroic week followed by two disrupted weeks is usually less useful than training you can repeat.
Next, look at progression. Doing exactly the same distances, paces and workouts for months can maintain fitness without giving your body much reason to improve. Progression might come from a gradual increase in volume, a longer sustained effort, better-quality intervals, long-run development or a more specific workout. It does not mean every week has to be harder than the last.
The opposite problem is just as common: progressing too aggressively. More kilometres, more hard sessions and faster easy runs can increase fatigue faster than fitness. Weekly distance on its own can hide that. Why 50 Kilometres Is Not Always 50 Kilometres shows how two weeks with the same mileage can create very different training demands.
Intensity distribution is worth checking as well. If easy days keep drifting into moderate efforts, you can end up carrying enough fatigue to blunt the quality of the sessions that are supposed to be hard. That does not mean every runner needs the same training model, but there should be a clear reason for the intensity of each session.
Recovery is part of the training process, not time lost between workouts. If sleep is poor, life stress is high, your legs stay sore and every run feels harder than normal, adding more training may make the problem worse. Running readiness can help you judge whether the planned session still fits the body doing it that day.
It is also important to separate performance potential from training tolerance. A fast 5K or 10K can show strong aerobic fitness, but it does not automatically mean you are ready for a large jump in marathon volume. A Fast 10K Doesn’t Mean You’re Ready for More Marathon Training explains that distinction.
Finally, measure progress in more than one way. A personal best is obvious, but improvement can also show up as a faster pace at the same effort, lower effort at the same pace, better repeatability in workouts, stronger long runs or more stable training across several weeks.
If you have genuinely plateaued, resist the urge to throw random extra training at the problem. Look at consistency, progression, intensity distribution, recovery and whether your current plan still reflects your fitness. Better-targeted training usually solves more than simply harder training.
by smartrunningcoach | Oct 13, 2026 | Uncategorized
Easy runs can feel hard when fatigue, poor recovery, heat, humidity, hills, stress, illness or recent training load raises the effort required at your usual pace. One difficult easy run is not automatically a warning sign. If easy running repeatedly feels harder than normal, slow down and look at the wider pattern before forcing the pace.
An easy run should feel controlled, but easy pace is not a fixed number. The pace that feels relaxed after two good recovery days may feel very different near the end of a demanding week. That does not necessarily mean you have lost fitness. It may simply mean you are carrying more fatigue.
This is why training load is about more than weekly distance. The duration, intensity and arrangement of your sessions all affect how much stress you are trying to absorb. Two runners can cover the same distance and finish the week with very different levels of fatigue.
Conditions matter too. Heat and humidity increase physiological and perceptual strain, which can make a normal pace feel harder. Wind, hills, trails and uneven surfaces can do the same. If you insist on matching your normal pace regardless of the conditions, an easy run can quietly become a moderate session.
Sleep and life stress can add to that load. One poor night does not automatically mean you should skip training, but several poor nights combined with a hard training block can change how a routine run feels. If sleep is the main issue, start with how to adjust training after a bad night’s sleep.
Heavy legs are another common reason easy running feels harder. Sometimes the first 10 or 15 minutes feel flat and your legs gradually loosen up. Other times the heaviness gets worse and your usual easy effort remains unusually high. Should You Run When Your Legs Feel Heavy? explains how to tell the difference.
It is also worth checking whether your easy runs are actually easy. Pace can creep up without you noticing, especially when fitness improves. A pace that looks comfortable on paper can still be too demanding if you are turning most days into steady efforts.
Successful endurance training usually keeps a large proportion of work at lower intensity, even though the exact distribution varies between athletes and training phases. Our review of polarized vs pyramidal training explains why there is no single perfect split, but also why easy running still has an important job.
Look for trends rather than reacting to one run. If a single easy session feels poor after a stressful day, back off the pace and move on. If easy runs feel hard for several days, your performance is slipping and you are not recovering between sessions, the pattern deserves more attention.
At that point, reducing load or using a recovery week may be more useful than pushing harder. Easy running should support the rest of your training. When it repeatedly becomes another session you need to recover from, something in the bigger training picture may need to change.
by smartrunningcoach | Oct 13, 2026 | Uncategorized
You can move runs around in a marathon training plan, but the structure of the week is important. Easy runs are usually the simplest to shift. Hard workouts and long runs need more care because moving them can reduce recovery time and leave demanding sessions too close together. The safest approach is to rearrange the week, not just the individual run.
A marathon plan gives your training structure, but it should not fall apart the moment real life changes. Work, travel, family commitments and recovery needs can all force a session to move. It’s not that you can’t move the run… It’s just what effect it has on the rest of the week.
Easy runs are normally the lowest-risk sessions to move. Swapping an easy day with a rest day often changes very little, provided you still keep enough recovery around the harder work. The bigger problems start when a change puts two demanding sessions back to back or removes the recovery that made the original week work.
Hard sessions such as intervals, tempo runs and hills create more fatigue. If you move one, look at what sits before and after it. High-intensity sessions the day before a long run for example, aren’t a great idea.
The same principle applies when you are deciding whether to replace a hard run with an easy run. The goal is not to protect every box on the calendar. It is to protect the purpose of the training week.
For example, imagine you have intervals on Tuesday, an easy run on Wednesday and a long run on Saturday. If Tuesday becomes impossible, moving the intervals to Friday solves the diary problem but creates a recovery problem. You would now be asking your body to complete two demanding sessions on consecutive days.
A better option might be to move the intervals to Wednesday, move the easy run, shorten the quality session or let it go if there is no sensible place for it. The right answer depends on the importance of that workout, how much fatigue you are carrying and what the rest of the week looks like.
If the session has already been missed, avoid treating it like training debt. Our guide on what to do if you miss a marathon training run explains why trying to squeeze every missed kilometre back into the week can create more problems than it solves.
Long runs deserve even more attention because they place a greater demand on the body than a routine easy day. Moving a long run by one day can be perfectly reasonable when you are healthy and recovered, but the new position still needs to leave enough space before your next key session.
If the long run itself is the problem, use the same decision-making process described in what to do if you miss your long run. One missed long run does not need to trigger a scramble to make up the distance.
The reason you are moving your run needs to be considered as well. Moving a session because of a meeting is different from moving it because you have had several poor nights of sleep, your legs are unusually heavy or your normal easy pace suddenly feels hard. A calendar problem may only need a calendar solution. A recovery problem may need a training adjustment.
That is where day-to-day running readiness becomes useful. The plan tells you what the intended session is. Readiness helps you decide whether today is still the right day to do it.
A simple rule is to protect the spacing between demanding sessions, keep easy days genuinely easy and avoid squeezing missed mileage into gaps just because it was written on the plan. Marathon fitness is built through consistent training over many weeks. Moving Tuesday to Wednesday is rarely the issue. Turning one small change into a badly arranged week is.
