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The Science Behind Your Training – Proving the Fitness Myths

Marginal Gains – Finding the Right Supplements to Boost Peak Performance  

The theory of marginal gains can be summed up as the 1% margin for improvement in everything you do. When it comes to training, this can be down to a variety of factors including equipment, diet, sleep and nutrition.

To test the theory of marginal gains, we investigated the impact that four different supplements can have on one athlete, whilst keeping all elements of their training, equipment and conditions exactly the same.

Our Subject

Our test subject was a well-trained mid 30-year-old male. He is 6.2’ and 72kg. He is an experienced runner, cyclist and triathlete. He trains regularly and is looking for marginal gains to increase his performance.

The Test

The test was a 20km time trial performed on a Wattbike. The distance is one often performed by amateur cyclists, but it also represented a realistic personal training session time, as well as an excellent fitness test distance.

Our test subject was required to cycle the distance initially without any supplements, giving us a control time. He was then tested on four separate occasions over the same distance, on the same bike, in the same conditions; each time one of the four supplements was used.

The Four Supplements

We chose to measure our subject using the following four supplements:

  • Isotonic Gel – One SiS GO Isotonic Gel 60 minutes pre-trial

  • Caffeine – 4mg/kg 60 minutes pre-trial

  • Nitrate (Beetroot Juice) – 400mg dietary nitrate 60 minutes pre-trial

  • Beta Alanine – 1.5g between meals in the two days leading up to the trial

This is what we found.

Time taken to complete the course

Our subject beat his original time with each of the four supplements.


By beating his time by 1% each time, he’s successfully secured a marginal gain simply by adding one different element to his training; a supplement.

But for two of our supplements (Caffeine, and Beta Alanine), he’s increased his time by over 2%.

We analysed the two of them in more detail.

Beta Alanine vs. Caffeine

Proposed Benefits of the two supplements

Beta alanine is proposed to work as a buffer inside the cells. This means that when we exercise, the pH drop that usually occurs, resulting in fatigue is slowed down. This should result in decreased RPE (rate of perceived exhaustion) leading to increased time trial performance.

Caffeine has been found to reduce feelings of exertion during endurance exercise for a given workload.

Where did we get our gains?

Overall Power and Percentage Difference vs. Overall Speed and Percentage Difference



In basic terms we can see that for both adding around a 6% difference in terms of power and a 2% difference in speed, will result in a 2% better time than without any supplements.

Beta Alanine is just out in front of Caffeine in terms of both power and speed, and marginal gains is about the smallest or margins. It’s clear both caffeine and beta alanine are superior supplements for these purposes, but where does the 0.2% difference between the two actually come from?

To fully understand we looked at both heart rate and rate of perceived exhaustion (RPE).

Rate of Perceived Exhaustion

The RPE for Beta Alanine levelled out around minute 13 (stage 3 on the above graph), while Caffeine continued to increase, this means that with caffeine our subject continued to feel fatigue throughout the course, increasing as he cycled. It’s with this supplement that our test subject also had the highest RPE overall, meaning that despite the fact he was able to push his body more than without supplements, he felt it more.

It’s this factor at this specific minute (minute 13), at the half way point of the trial that appears to be the first element of our marginal gain, as both the speed and power when using Caffeine as a supplement drop here.



Marginal Gains Observation 1 Our rider’s performance drops due to hard he perceives the activity to be. A supplement that maintains a steady RPE will increase peak performance.

Heart Rate

Again all four supplements kept our test subject’s heart rate above the control test.

Again we can see a dip and plateau for caffeine at minute 13 (although not as dramatic as RPE), contributing to the drop in speed and power at this point.

All other supplements gradually increase the heart rate throughout exercise, peaking in the last few minutes, in line with the natural ride (control).

Marginal Gains Observation 2 – a supplement that increases a subject’s heart rate, while keeping a steady increase throughout physical exercise will boost peak performance.

The Final Push

The RPE is the highest for all our tests in the final stages of each time trial. This is as you would expect as our rider is pushing himself to get the best time.

We can see a final push in power for both our supplements at minute 23, however when using Beta Alanine this push continues to the finish line, while caffeine again fluctuates. Again this can be attributed to the RPE at this point.


Here, the true effects of Beta Alanine are clear. Our rider is able to push on in the final stages due to the impact the supplement has within his cells.

We can also see that it was the only supplement that enabled our rider to finish with more power than he began in minute one.

Marginal Gain 3 – A supplement that enables you to maintain a steady rate of power, peaking in the final stages of activity will give you the best increase when it comes to peak performance.

A summary of our findings

We can see the slightest of marginal gains between Beta Alanine and Caffeine. This can be attributed to Beta Alanine performing in line with its expected attributes. It succeeded in slowing down fatigue, decreasing RPE and leading to increased time performance.

Caffeine may have increased time performance, but not due to its proposed benefits as our rider struggled with fatigue affecting his RPE significantly half way through the trial.

To get the best impact from your chosen supplement, the following should therefore happen:

  • Maintain a steady RPE

  • Increase and maintain your heart rate

  • Increase power, peaking in the final push

gceditor | 29/12/2016 00:00:00

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