Having recently returned from the Ironman World Championships in Kona, “Carbo Loading” in the race week was something mentioned is just about every conversation. Like it was a fact. However, carbohydrate loading prior to an endurance event is indeed ubiquitous – but why? And how should we do it? Let’s discuss.

Energy stores

This will be a refresher for regular readers of my blog, or of our monthly summary of the latest endurance science research, TSS – but understanding the whys and hows of pre-exercise carbohydrate loading requires some knowledge of the energy stores we have in the body, and how we use them during exercise.

During endurance exercise, particularly relatively even-paced events like marathons or Ironman triathlons, almost all of the energy production we need to power muscle contractions come from aerobic metabolism, or the breakdown of fuels in oxygen-dependent pathways. That’s why we have lungs, our heart, blood, and blood vessels,...

Lots of athletes will know the feeling. It’s a bit like there’s a small knot forming beneath the skin, in your hamstrings or calves. The tension grows, and the muscle starts to contract involuntarily. The cramp usually begins as repeated twinges or flutter-like waves of contractions. It only builds from there, and shifts from discomfort to sharp, intense pain. You have to stop to stretch it out, which relieves the cramp momentarily, before it comes back, over-and-over again.

Cramp can be debilitating for some athletes, effectively ending races in a painful stop-start jerk to the finish. For lucky athletes, it never seems to happen at all. Exercise-induced cramps are, amazingly, still a bit of a mystery.

In this blog, we’ll discuss what we think might be going on with exercise-induced muscle cramping, and suggest some strategies that athletes might use to combat them.

 What causes exercise-induced muscle cramping?

Like I said, the precise cause of...

Those of you that read our blogs, or subscribe to our monthly Training Science Summaries, will know that we often write about ‘durability’. Durability has been one of our key research areas over the last few years, and something that is seeing a lot of attention in our field by other researchers, too. I think durability has massive implications not only for endurance performance, but also for the day-to-day decisions we make in endurance training.

In this blog, I’m going to provide an update on the durability research – what we know, what we don’t know, and what the implications are for athletes. However, I’ll before we get into durability, I’ll discuss physiological profiling.

Physiological Profiling and Endurance Training

I often have my athletes perform incremental exercise tests. With an incremental exercise test, we can estimate the athlete’s overall aerobic capacity or VO₂max, how economical their movement is, and their speed or...

Effective endurance training is all about stress management, and the balance between stress and recovery. Individual training sessions generate physiological stress – elevations in temperature, heart rate, and stress hormones, changes in pH, depletion of fuel stores, and so on. The stress of individual training sessions is what triggers the adaptive response we look for with training, and this occurs during recovery (1). However, too much physiological stress with inadequate recovery will eventually lead to fatigue, overreaching, and maladaptation, as anyone who has dug themselves a hole with a hard training block can testify.

Therefore, when planning a training programme, and then regulating and monitoring that training programme, we are managing the balance between stress and recovery. We want to ensure there is enough stress to stimulate adaptation, but not so much that we become fatigued, overreached, and burned out. We want to make sure our recovery processes are geared...

I talk a lot about physiological profiling, and how getting tested in an exercise physiology laboratory can be really helpful for refining your training. However, I also know that many athletes do not have access to exercise physiology labs for this testing.

Accordingly, I’ve put together a couple of calculators on the Endure IQ website that you can use to get decent estimates of things like intensity thresholds using easy-to-access field test data.

In this section we are going to talk about the metabolic calculator. I’ll walk you through how to perform the field tests to get the necessary data. But we also include calculators for critical swim speed, functional thresholds power, and critical running speed.

#1: The metabolic calculator

Our first calculator, which you can find here, uses field test estimates of your VLa_max and VO₂max to predict your two lactate thresholds – which we use to determine training zones – and your Fat_max, or the intensity at which...

I talk a lot about physiological profiling, and how getting tested in an exercise physiology laboratory can be really helpful for refining your training. However, I also know that many athletes do not have access to exercise physiology labs for this testing.

Accordingly, I’ve put together a couple of calculators on the Endure IQ website that you can use to get decent estimates of things like intensity thresholds using easy-to-access field test data.

In this section we are going to talk about the critical swim speed calculator. I’ll walk you through how to perform the field tests to get the necessary data. But we also include calculators for fat max/lactate thresholds, functional thresholds power, and critical running speed.

Field test estimate of critical swim speed

The Critical Swim Speed calculator needs to best paced time trials over 200 m and 400 m. This can be done within the same session, so it’s important to have a good warm up before the...

I talk a lot about physiological profiling, and how getting tested in an exercise physiology laboratory can be really helpful for refining your training. However, I also know that many athletes do not have access to exercise physiology labs for this testing.

Accordingly, I’ve put together a couple of calculators on the Endure IQ website that you can use to get decent estimates of things like intensity thresholds using easy-to-access field test data.

In this section we are going to talk about the metabolic calculator. I’ll walk you through how to perform the field tests to get the necessary data. But we also include calculators for fat metabolism/lactate thresholds, critical swim speed and critical running speed.

Field test estimate of cycling functional threshold power (FTP)

If you’re a cycling, you have likely heard of FTP – which is an indicator of the power you can hold for an hour. We can use FTP to generate training zones, and we can estimate FTP using a...

I talk a lot about physiological profiling, and how getting tested in an exercise physiology laboratory can be really helpful for refining your training. However, I also know that many athletes do not have access to exercise physiology labs for this testing.

Accordingly, I’ve put together a couple of calculators on the Endure IQ website that you can use to get decent estimates of things like intensity thresholds using easy-to-access field test data.

In this section we are going to talk about the metabolic calculator. I’ll walk you through how to perform the field tests to get the necessary data. But we also include calculators for fat metabolism/lactate thresholds, critical swim speed and functional threshold power.

Field test estimate of critical run speed: 5-km time trial

Our running field test is a 5-km effort – how fast can you complete 12.5 laps of 400-metre athletics track, although you can also complete the on your favourite flat running route. If...

As you can imagine, I get asked a lot of questions about training. What’s the best type of training to improve VO₂max? How much protein do endurance athletes need? Do I need to do strength training? How early should I taper? These are all great questions, and I love working with athletes to find the answer.

Alongside questions, there are a number of assumptions – or myths – that come up again and again when working with athletes, that I work hard to bust. In this blog, I am going to try and bust six of the biggest endurance sports myths.

Myth #1: Training the gut enhances carbohydrate use.

“I consume carbohydrates at high rates during training, to train my gut to digest and absorb carbohydrates at higher rates. That allows me to get more energy from sports drinks and gels during racing.”

Gut training – the practice of consuming carbohydrates at very high rates during training – has been investigated by researchers. The idea behind gut...

Endurance sport challenges many aspects of our physiology, not least our metabolism and our fuel stores. Our primary energy sources that broken down to power exercise are fat and carbohydrate (1). The body’s fat energy stores are vast and effectively limitless during exercise, while our carbohydrate energy stores – endogenous muscle and liver glycogen – can be depleted to low concentrations during prolonged, vigorous exercise (2–4). Therefore, a vast literature has emerged over the last ~100 years on the importance of our carbohydrate energy stores for endurance performance, and strategies to preserve them, such as through consumption of exogenous carbohydrate in sports drinks and gels. Accordingly, in endurance sport we dedicate a lot of time and effort to planning the optimal dose, type, and timing of carbohydrate ingestion before and during exercise to maximise our performance.

In this blog, we are going to discuss how those of us in performance physiology...