Power-Weight Ratio: What's The Best Strategy For Cyclists To Improve Their Watts Per Kilo?

In the world of cycling, improving power-weight ratio is always a hot topic when discussing physical development.

The objective is pretty simple: How much power can you churn out whilst being as light as possible. In return, skyrocketing your watts per kg.

This is certainly beneficial during events and races that go against gravity, i.e. when riding uphill.

However, many cyclists will take this to the extreme which can negatively impact their physical and mental health/performance (RED-S), along with their relationship with food and quality of life (QOL). Ultimately, lighter doesn’t always mean faster, and in many cases, it can ruin your cycling career and love for the sport.

Needless to say there’s a bucket load of issues that can come from being overly tunnel versioned with dropping weight. As this is such an important topic, we’ll be covering this in much greater detail soon!

But, If bodyweight reduction occurs in a healthy manner that helps the rider achieve an appropriate body composition to support performance and health…The question is:

What is the best way to develop your power-weight ratio?

Well, Lunn et al (2009) designed an awesome study to help us figure this out. Over a 10 week training period, they split a group of experienced competitive cyclists into three groups: ⠀
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Group 1 aimed to maintain bodyweight, but looked to improve their power-weight through their TRAINING ONLY which consisted of supramaximal sprint interval sessions (SIT).⠀
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Group 2 aimed to maintain their normal (lower intensity training), but looked to improve their power-weight through WEIGHT LOSS ONLY (calorie restriction).⠀
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Group 3 aim to tackle this issue from both ends where they followed the same SIT protocol as group 1, but followed the same weight loss diet as group 2.

The Results:

Group 1: As expected, these cyclists maintained bodyweight but significantly improved peak and average power output, thus improving their power-weight ratio.⠀
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Group 2: These cyclists lost 5kg on average (80.3kg down to 75.3kg), improved peak power output (although not statistically significant) but maintained average power output. Therefore improved power-weight ratio primarily through being lighter on the bike.⠀
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Group 3: These cyclists experienced similar, but slightly worse results than group 2: no significant improvements in both peak and average power output. They did however lose 5.5kg (78.9kg down to 73.4kg). Therefore, power-weight ratio did improve via weight loss only. This is interesting as you’d think that losing weight AND doing specific sessions to improve power output would skyrocket power-weight, but it didn’t.⠀
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In fact, the greatest improvements were seen in group 1 - I.e. placing all their efforts on performance and not worrying about body fat loss.

There are a few caveats here:

1) Group 1’s av. Bodyweight was 69kg, therefore they didn’t need to drop body weight as their body fat was sub 10%. In this case, you would advocate performance only to improve power-weight.

I’d take an educated guess in saying that that if group 1 were to follow a calorie restricted diet (same condition as group 3), their results would have been far worse. I.e. being in a 500kcal deficit at 8-10% body fat does not feel the same as being in a 500kcal deficit at 15-20% body fat. This is where RED-S (relative energy deficiency in sport) can occur.

2) I would also assume that group 3 may have struggled to complete the SIT sessions to a high standard as high intensity performances will be compromised under calorie and carbohydrate restriction (and adaptation).

The SIT sessions will be far more taxing on the nervous system and on their glycogen stores. From experience, food focus (desire to eat) typically increases, mood and QOL decreases and you’re constantly fighting to stay in a calorie deficit. The additional depletion of glycogen stores will also increase RPE (ratings of perceived exertion) during exercise and generally make everything feel a lot harder.

Essentially, you’ll be saying ‘I just didn’t have the legs today’ far more than you’d like to.

From experience working with cyclists of all riding disciplines, the best time to drop body fat is during periods of less intense/base training where optimal performance isn’t the highest priority. I.e. they can sit in a nice calorie deficit, maintain performance and health (immune function), whilst dropping the kilos steadily throughout the weeks without worrying about ‘surviving’ their training.

Although the rate of fat loss between groups 2 and 3 were similar (~0.5kg/week on average) and are aligned with the current recommendations of 0.5-1% loss in bodymass per week via body fat, the subjective experiences are vastly different.

I.e. sitting in a 500kcal deficit after a day’s ride in Z2 is not the same as sitting in a 500kcal deficit after an intense day on the bike, especially if you’re in the middle of a hard training phase. Energetically speaking, it’s quite similar, but the way it makes you feel can be completely different.

Therefore, although group 3 had the same results as group 2, I would imagine that the processed sucked a lot more - Imagine under eating, under fuelling and under recovering from intense training to not get any superior results than the group whose training was far more chilled and relaxed. You’d be cursing.

The main take home message is this:

If you’re already lean and achieved an appropriate weight/body composition that’s specific to your cycling discipline, we’d highly recommend shifting the focus from fat loss to performance to achieve a greater power-weight ratio. Digging yourself into a hole to become lighter is futile, and potentially harmful to your health and performance.

If you do have body fat/weight to lose, then doing so during periods where training intensity is lower would be ideal as both training and QOL will be better. Then, when you transition into a harder training phase, you’d increase calorie intake to maintenance and support session performance. You’d meet the body’s demands and fuel for the work required.

Therefore, over the course of a year, power-weight ratio will improve from both angles. This is where long term planning is essential if you’re looking to maximise your physical development.

If this post helped shed some light on the matter, we’d be incredibly grateful if you could share this with a friend, family member or team mate that may benefit from this content too. Thank you so much!

- Coach Chris