What benefits have you experienced using power?

Runner feedback (depicted as a green thumbs up and a red thumbs down)

𝐖𝐡𝐚𝐭 𝐛𝐞𝐧𝐞𝐟𝐢𝐭𝐬 𝐡𝐚𝐯𝐞 𝐲𝐨𝐮 𝐞𝐱𝐩𝐞𝐫𝐢𝐞𝐧𝐜𝐞𝐝?

This is part of a series of posts on runners’ feedback about Running with Power.

Based on survey responses and book research, here are the top three benefits runners experienced using power.

𝐀𝐛𝐥𝐞 𝐭𝐨 𝐭𝐫𝐚𝐢𝐧 𝐭𝐨 𝐭𝐚𝐫𝐠𝐞𝐭𝐬

Sounds simple? Yet with power, according to the feedback, it’s much easier to do. First, the targets are numbers or number ranges, rather than ‘10k pace’ or ‘zone 2’ (when your heart rate seems determined to stay in zone 3). Second, they’re based on your current fitness, adjusting as you get fitter. Finally, you just have to run to effort, which changes to match your route, however hilly it might be.

𝐂𝐨𝐧𝐬𝐢𝐬𝐭𝐞𝐧𝐜𝐲

The #1 goal of training – being able to follow the plan without getting injured. Training to targets matched to individual fitness gave runners confidence in the plan, allowing them to ‘relax’ and enjoy the experience. And with plans written to add training load slowly and carefully, runners experienced a powerful feedback loop – clear targets => able to run to target => confidence in the plan => increasing fitness without injury => targets adjust to match fitness => able to run to target…

𝐈𝐦𝐩𝐫𝐨𝐯𝐞𝐝 𝐫𝐚𝐜𝐞-𝐝𝐚𝐲 𝐩𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞

Power offers a couple of race planners, both of which produced power-based targets for races and events that were not only achievable, but for many runners, accurate to within a few watts, and to within a minute or two (over a marathon).

But it was at the start that power was most beneficial, providing a target that prevented runners from starting too fast (given the excitement and the ‘freshness’ that’s usually present at the start of many events).

𝐎𝐭𝐡𝐞𝐫 𝐫𝐞𝐚𝐬𝐨𝐧𝐬

There were many other benefits runners experienced using power, including: being able to measure fitness improvements; power is responsive, matched to effort; gaining a better understanding of their physiology and capabilities; finding a great community of runners all learning how best to use power.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

What benefits have you experienced using power?

Why did you start running with power?

Runner feedback (depicted as a green thumbs up and a red thumbs down)

𝐖𝐡𝐲 𝐝𝐢𝐝 𝐲𝐨𝐮 𝐬𝐭𝐚𝐫𝐭 𝐫𝐮𝐧𝐧𝐢𝐧𝐠 𝐰𝐢𝐭𝐡 𝐩𝐨𝐰𝐞𝐫?

This is part of a series of posts on runners’ feedback about Running with Power.

Based on survey responses and book research, here are the top four reasons why runners started using power.

𝐈𝐭’𝐬 𝐣𝐮𝐬𝐭 𝐨𝐧𝐞 𝐧𝐮𝐦𝐛𝐞𝐫

The most popular reason – power gives you one number that changes as your effort changes. And it represents your effort when on the flat, up and down hills, or running in wind. You can even adjust for running in heat, high humidity or at altitude. You just need to ‘run to the number’.

𝐏𝐚𝐜𝐞 𝐚𝐧𝐝 𝐡𝐞𝐚𝐫𝐭 𝐫𝐚𝐭𝐞 𝐰𝐞𝐫𝐞𝐧’𝐭 𝐰𝐨𝐫𝐤𝐢𝐧𝐠

Whether it was because of pace issues on hilly routes, heart rate lags when starting or stopping intervals, or not being able to accurately judge effort, runners were having difficulties using other methods of measuring how hard they were running.

𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐭𝐡𝐚𝐭 𝐰𝐨𝐫𝐤𝐬

Many non-power plans come with a risk of overtraining or leaving potential training gains unrealised. Power uses narrower target ranges within zones, and the power-based plans from Steve Palladino have worked for hundreds of injury-free runners.

𝐁𝐞𝐭𝐭𝐞𝐫 𝐫𝐚𝐜𝐞 𝐫𝐞𝐬𝐮𝐥𝐭𝐬

Runners were looking for a way to improve their race results, qualify for Boston (or similar), or to find a way to improve their race pacing. While power can’t guarantee better results or a qualifying time, race planning with power uses current fitness, stamina and running effectiveness to determine personalised race targets.

𝐎𝐭𝐡𝐞𝐫 𝐫𝐞𝐚𝐬𝐨𝐧𝐬

There were many other reasons why runners started using power, including: power is based on physiology; it’s backed by years of research (from cycling and running); it uses data-driven insights; it can be used on a treadmill or in bad GPS locations.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Why did you start running with power?

Feedback from runners using power

Runner feedback (depicted as a green thumbs up and a red thumbs down)

𝐅𝐞𝐞𝐝𝐛𝐚𝐜𝐤 𝐟𝐫𝐨𝐦 𝐫𝐮𝐧𝐧𝐞𝐫𝐬 𝐮𝐬𝐢𝐧𝐠 𝐩𝐨𝐰𝐞𝐫

A few weeks ago, posts outlined reasons you might choose to use power to measure how hard you’re running.

This week, posts will cover this in a little more depth, exploring the following questions:
❓ Why did you start running with power?
❓ What benefits have you experienced?
❓ What difficulties have you experienced?
❓ What advice would you give to someone not yet Running with Power?

The posts will summarise the top themes from feedback received when asking runners these questions – feedback from two annual surveys, and feedback gathered while researching two of my books (‘Why’ and ‘Getting Started’).

Here are my answers to those questions.

𝐖𝐡𝐲?

I wanted to break sub-4 for the marathon and found training using pace or heart rate difficult in several ways. Power (training using effort) just made sense to me … plus, I like working with data and metrics.

𝐁𝐞𝐧𝐞𝐟𝐢𝐭𝐬?

There’s magic in the numbers – as a runner using power, I can: measure (and track) my fitness; set precise workout targets; monitor my training load; set achievable race-day targets.

As a coach, power makes it possible to set workout goals that I know will be usable whatever route my runners choose to take (hilly or not). And the insights that are possible using power data make fine-tuning (or course-correcting) so much easier.

𝐃𝐢𝐟𝐟𝐢𝐜𝐮𝐥𝐭𝐢𝐞𝐬?

It was expensive – I bought a running watch and a Stryd footpod. And it was difficult to use, although the Stryd PowerCenter these days is light years ahead of where it was when I first started.

While it is now possible to buy a running watch with a power meter inside, it’s complex to calculate power metrics – hopefully that’ll change in the next few years.

𝐀𝐝𝐯𝐢𝐜𝐞?

Go for it. Based on using power since 2018, I firmly believe Running with Power is the most effective way to train.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Feedback from runners using power

Race-specific training

A runner experiencing Training Stress

𝐑𝐚𝐜𝐞-𝐒𝐩𝐞𝐜𝐢𝐟𝐢𝐜 𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠

Stress Balance, based on your stress scores, includes both intensity and duration, but it doesn’t provide any insight into the distribution of running intensities in your training.

A longer run at a lower intensity can produce the same stress score as a shorter run at a higher intensity.

Yet intensity is important, as the adaptations from higher intensities may be quite different than those from lower intensities.

And you may want to match those adaptations to your goal race – training for a marathon may have a different mix of intensities than training for a 5k.

𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐈𝐧𝐭𝐞𝐧𝐬𝐢𝐭𝐲 𝐃𝐢𝐬𝐭𝐫𝐢𝐛𝐮𝐭𝐢𝐨𝐧 (𝐓𝐈𝐃)

A TID chart groups your time spent at each intensity into 3 or more groups, then displays the result as a stacked bar chart, with each stacked bar representing a week of training.

When Running with Power, the groups are typically ranges based on percentages of your Threshold Power. This ensures that when your Threshold Power changes, your adjusted intensities are still relative to what you’re capable of (and it means you don’t need to adjust the chart).

You can produce the chart for completed workouts to check the mix that you ran. Or you can produce the chart for planned workouts, to adjust the mix you’re planning to run, using planned stress scores).

The TID chart is the third key metric for monitoring your training (along with Stress Balance and Ramp Rate).

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Race-specific training

The danger of ramping up too quickly

A runner experiencing Training Stress

𝐓𝐡𝐞 𝐝𝐚𝐧𝐠𝐞𝐫 𝐨𝐟 𝐫𝐚𝐦𝐩𝐢𝐧𝐠 𝐮𝐩 𝐭𝐨𝐨 𝐪𝐮𝐢𝐜𝐤𝐥𝐲

Training stresses your body, encouraging it to adapt.

But it’s a balance. Stress the body too little, and it will not adapt; stress it too much or too quickly, and it will break down instead of adapting; stress the body correctly, and sustained long-term improvements are possible.

And the stresses are cumulative – as you continue to train, you continue to encourage adaptations.

Your training load is the sum of these cumulative stresses. Monitoring your training load helps ensure your training is productive, and that you minimise injury risk.

𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐋𝐨𝐚𝐝 𝐦𝐞𝐭𝐫𝐢𝐜𝐬

Your Stress Balance indicates whether your training is productive, with a negative (but not too negative) score indicating productive training.

Your Ramp Rate shows if you may be adding training load too quickly, replacing ‘the 10% rule’ with a metric based on your training volume and intensity.

𝐑𝐚𝐦𝐩 𝐑𝐚𝐭𝐞

Ramp Rate is the week-on-week difference in your Chronic Training Load or your 42-day weighted average (depending on which set of metrics you’re using).

Why week-on-week? Because Long Runs will tend to impact your training load more than shorter interval sessions or easy/recovery runs.

Using a week-on-week calculation will ‘smooth out’ any fluctuations caused by your workout mix while still producing a useful metric.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

For more about Ramp Rate, see Training Load Progression in the Facebook group Palladino Power Project.

The danger of ramping up too quickly

Achieving a Stress Balance

A runner experiencing Training Stress

𝐀𝐜𝐡𝐢𝐞𝐯𝐢𝐧𝐠 𝐚 𝐒𝐭𝐫𝐞𝐬𝐬 𝐁𝐚𝐥𝐚𝐧𝐜𝐞

Stress Scores, calculated for each workout, represent each workout’s metabolic stress – its impact on your body.

You can use these scores to model the shorter-term and longer-term impacts from each workout.

Combining these, you can obtain a Stress Balance, indicating whether your training is ‘productive’.

𝐏𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐯𝐞 𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠

How does your Stress Balance help ensure your training is productive?

Your stress balance is the difference between the longer-term impacts and the shorter-term impacts:
🔹 A very positive balance indicates detraining or a lack of any meaningful training.
🔹 A positive balance may indicate tapering or a missed workout.
🔹 A negative balance indicates productive training – enough stress to encourage adaptations, but not so much that there is a greater risk of injury or over-training.
🔹 A very negative balance may indicate over-training, with a greater risk of injury.

𝐇𝐨𝐰 𝐚𝐜𝐜𝐮𝐫𝐚𝐭𝐞 𝐢𝐬 𝐲𝐨𝐮𝐫 𝐒𝐭𝐫𝐞𝐬𝐬 𝐁𝐚𝐥𝐚𝐧𝐜𝐞?

You can use your stress balance to monitor your training, but be aware that:
🔹 You need 80+ days of workout data for your stress balance to be accurate (because of the way the model works)
🔹 You should track your scores and compare them to how you actually feel to build your experience of what your stress balance represents (for you)

Nevertheless, your stress balance is a useful way to monitor whether your training is productive.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Training Stress – a two-sided coin!

A runner experiencing Training Stress

𝐓𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐒𝐭𝐫𝐞𝐬𝐬 – 𝐚 𝐭𝐰𝐨-𝐬𝐢𝐝𝐞𝐝 𝐜𝐨𝐢𝐧!

On one side of the coin, the reason you’re training – improving your performance, your fitness, your speed, your ability to run further for longer.

One the other, the impact of your workouts – fatigue, muscle soreness, dehydration, injury risk … the list could go on.

Can a single Stress Score be used to model the changes in your performance ability:
🔹 in the shorter-term, from stress to which your body has not yet adapted?
🔹 in the longer-term, from stress to which your body may have adapted?

𝐓𝐡𝐞 𝐑𝐞𝐬𝐞𝐚𝐫𝐜𝐡

Research into the effects of training stress has resulted in various models:
✅ Rowbottom proposed a Stimulus, Fatigue, Recovery, Adaptation model, sometimes referred to as the supercompensation model
✅ Banister proposed an Impulse-Response model, popularised in the TRIMP metric based on Heart Rate measurements
✅ Allen, Coggan and McGregor adapted the Impulse-Response model for use with power, encapsulating it in the Performance Manager model.

𝐓𝐡𝐞 𝐏𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞 𝐌𝐚𝐧𝐚𝐠𝐞𝐫 𝐦𝐨𝐝𝐞𝐥

The model has the following components:

  1. A Training Stress Score (TSS)
  2. A Chronic Training Load (CTL), modelling longer-term adaptations
  3. An Acute Training Load (ATL), modelling shorter-term impacts
  4. A Training Stress Balance, indicating whether your training is ‘productive’

The Performance Manager model uses 𝑦𝑜𝑢𝑟 Stress Scores (per workout) to calculate personal training metrics that indicate whether 𝑦𝑜𝑢𝑟 training is productive – not too much, not too little, just right for you.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

For more information on the models, see:
🔹 Rowbottom, D.J., (2000), in Garrett, W.E., Kirkendall, D.T., (eds.). Periodization of Training. Philadelphia: Lippincott Williams & Wilkins.
🔹 Calvert, T.W., Banister, E.W., Savage, M.V., Bach, T., (1976) A Systems Model of the Effects of Training on Physical Performance
🔹 Allen, H., Coggan, A. & McGregor, S. (2019) Training+Racing with a Power Meter, 3rd Edition (pp. 158-160). Boulder: Velopress.
🔹 The Science of the TrainingPeaks Performance Manager on the TrainingPeaks website

Training Stress – a two-sided coin!

How do you handle training stress?

A runner experiencing Training Stress

𝐇𝐨𝐰 𝐝𝐨 𝐲𝐨𝐮 𝐡𝐚𝐧𝐝𝐥𝐞 𝐭𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐬𝐭𝐫𝐞𝐬𝐬?

Let’s face it, training is stressful.

It’s easy to overdo it, leading to injury and time spent recovering (rather than training).

But if you’re training for an event, a little stress is a necessity.

It’s a balance. Stress your body too little, and it will not adapt; stress it too much or too quickly, and it will break down instead of adapting; stress your body correctly, and sustained long-term improvements are possible.

𝐒𝐭𝐫𝐞𝐬𝐬 𝐒𝐜𝐨𝐫𝐞𝐬

Want to know how stressful your workout was? Calculate its Stress Score.

Stress Scores combine ‘how hard?’ and ‘how long?’

They represent the workout’s metabolic stress – its impact on your body.

𝐒𝐭𝐫𝐞𝐬𝐬 𝐒𝐜𝐨𝐫𝐞𝐬 𝐚𝐫𝐞 𝐫𝐞𝐥𝐚𝐭𝐢𝐯𝐞 𝐭𝐨 𝐲𝐨𝐮𝐫 𝐓𝐡𝐫𝐞𝐬𝐡𝐨𝐥𝐝 𝐏𝐨𝐰𝐞𝐫

A one-hour run at Threshold Power produces a score of 100.

Why?

Scoring relative to your Threshold Power means Stress Scores:
✅ match improvements in your fitness. As you become fitter, you can run the same workouts with less relative stress; or you can handle harder workouts for the same relative stress.
✅ match individual capabilities. If our thresholds are different and we run a workout together, your stress score for the workout will differ from my stress score for the same workout, reflecting our individual capabilities.

Stress Scores are the foundation for metrics you can use to monitor your training stress.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

For more information on Stress Scores, see:
🔹 What is TSS? on the TrainingPeaks website
🔹 Running Stress Score (RSS) on the Stryd website

How do you handle training stress?

Why power? Power can measure running form improvements

A runner looking powerful

𝐏𝐨𝐰𝐞𝐫 𝐜𝐚𝐧 𝐦𝐞𝐚𝐬𝐮𝐫𝐞 𝐫𝐮𝐧𝐧𝐢𝐧𝐠 𝐟𝐨𝐫𝐦 𝐢𝐦𝐩𝐫𝐨𝐯𝐞𝐦𝐞𝐧𝐭𝐬

Want to improve your finish times?

You have two choices:
✅ Work on your fitness – so you can run the event distance maintaining a higher effort than before
✅ Work on your form – so you can run faster for the same effort, run at the same speed for less effort, or both

𝐇𝐨𝐰 𝐝𝐨 𝐲𝐨𝐮 𝐰𝐨𝐫𝐤 𝐨𝐧 𝐲𝐨𝐮𝐫 𝐟𝐨𝐫𝐦?

You can work on your form using drills, plyometrics, strength and conditioning, mobility and other supplemental work.

𝐇𝐨𝐰 𝐜𝐚𝐧 𝐲𝐨𝐮 𝐦𝐞𝐚𝐬𝐮𝐫𝐞 𝐟𝐨𝐫𝐦 𝐢𝐦𝐩𝐫𝐨𝐯𝐞𝐦𝐞𝐧𝐭𝐬?

Running Effectiveness (RE) measures how effectively you convert power into forward motion.

It’s calculated as the ratio of speed to power = speed / power.

RE is a field-based measure similar to, but different from Running Economy (oxygen consumption at various speeds) or Running Efficiency (external mechanical power vs. metabolic power production), which both require lab-based testing.

Measure your RE before beginning your form work, then again at the end, comparing the results to see if you’ve made a positive difference to your Running Effectiveness.

𝐑𝐄 𝐜𝐚𝐧 𝐛𝐞 𝐚 𝐝𝐢𝐟𝐟𝐢𝐜𝐮𝐥𝐭 𝐦𝐞𝐭𝐫𝐢𝐜 𝐭𝐨 𝐦𝐞𝐚𝐬𝐮𝐫𝐞

Why?

It’s affected by: your power meter; your weight; how hard you’re working; hills; wind; running shoes.

One way to track RE improvements is to use reference runs.

Every 3-4 weeks, run the same route at the same target intensities wearing the same running shoes.

Reference runs provide an opportunity to compare RE from one run to the next, so that you can see if you’re improving.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Running Effectiveness was proposed by Andrew Coggan, PhD, and measures how effectively you convert power into speed.

Power can measure running form improvements

Why power? Power provides metrics to manage your training load

A runner looking powerful

𝐏𝐨𝐰𝐞𝐫 𝐩𝐫𝐨𝐯𝐢𝐝𝐞𝐬 𝐦𝐞𝐭𝐫𝐢𝐜𝐬 𝐭𝐨 𝐦𝐚𝐧𝐚𝐠𝐞 𝐲𝐨𝐮𝐫 𝐭𝐫𝐚𝐢𝐧𝐢𝐧𝐠 𝐥𝐨𝐚𝐝

Your training load has two major components:
🔹 Your training balance – balancing the shorter-term and longer-term effects of your training to ensure your training is productive (not too much, not too little)
🔹 Your training progression – managing how you progress your training to avoid injury from adding too much too quickly.

Power provides metrics, based on your completed workouts, to manage your training load.

𝐇𝐨𝐰 𝐝𝐨𝐞𝐬 𝐩𝐨𝐰𝐞𝐫 𝐮𝐬𝐞 𝐜𝐨𝐦𝐩𝐥𝐞𝐭𝐞𝐝 𝐰𝐨𝐫𝐤𝐨𝐮𝐭𝐬 𝐭𝐨 𝐚𝐜𝐡𝐢𝐞𝐯𝐞 𝐭𝐡𝐢𝐬?

Power calculates a Stress Score for every workout, using the workout intensities and durations.

It uses the Stress Scores from every workout, along with your Threshold Power, to calculate training load metrics.

These metrics will be covered in more detail in an upcoming series of posts.

𝐖𝐡𝐲 𝐢𝐬 𝐢𝐭 𝐢𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐭 𝐭𝐨 𝐦𝐚𝐧𝐚𝐠𝐞 𝐛𝐨𝐭𝐡 𝐛𝐚𝐥𝐚𝐧𝐜𝐞 𝐚𝐧𝐝 𝐩𝐫𝐨𝐠𝐫𝐞𝐬𝐬𝐢𝐨𝐧?

Training stresses your body, prompting it to adapt and become fitter, improving performance.

But it’s a balance.

Stress the body too little, and it won’t adapt.

Stress it too much or progress too quickly, and it’ll break down instead of adapting.

Stress the body correctly, managing both balance and progression, and sustained long-term improvements are possible.

𝑺𝒉𝒐𝒖𝒍𝒅𝒏’𝒕 𝒚𝒐𝒖 𝒃𝒆 𝑹𝒖𝒏𝒏𝒊𝒏𝒈 𝒘𝒊𝒕𝒉 𝑷𝒐𝒘𝒆𝒓?

Questions?
📖 Getting Started

Power provides metrics to manage your training load