By Dr Dan Plews

In this blog I am going to discuss an essential metabolic coenzyme called NAD+, and why it is so essential to your health. Some of you may be aware of NAD+, but it is fair to say that NAD+ metabolism is one of the trickier areas of physiology I have discussed so far. Taking some time to discuss NAD+ is definitely worth it though, as changes in NAD+ appear to have strong implications in the negative effects of ageing and health benefits of exercise.

The physiology of NAD+

Nicotinamide adenine dinucleotide (NAD) is a metabolic coenzyme critical to the physiological function of all living cells. NAD exists in two forms: in an oxidised form as NAD+, and in a reduced form as NADH. Those of us that have studied exercise physiology and metabolism may be familiar with the concept of NAD as a means of linking the citric acid cycle to oxidative phosphorylation in the aerobic energy system. Specifically, in the oxidation of fats and carbohydrates, and in the citric acid cycle,...

One topic that has received increasing attention in the scientific and endurance sport community over the last few years is training under environmental heat stress. The benefits of training in the heat in preparation for a competition in a hot environment is well-established (3, 23). That process is called heat acclimatisation (or acclimation when performed in an artificial hot environment like a heat chamber), and is an effective means of improving an athlete’s thermoregulatory capabilities in order to tolerate the stress associated with the dual stresses of competitive work outputs and high environmental stress. That is not what this blog is about. Interested readers are directed to our course dedicated to preparing for long-distance triathlon competitions in hot environments (LDT 103).

In this blog we are instead concerned with whether training under environmental heat stress can be used as an additional stressor in order to promote endurance training adaptations relevant...

The question of “what should I eat before training”, is one that personally, I get asked a lot! Both by the athletes I coach, and by our Endure IQ education community (athletes and coaches). Up until now, I’ve always answered based on what I thought I knew, and what the literature pointed towards. However, to put it simply, the research just hasn’t been done in this space. That’s why I was super excited when I met my PhD student Jeff Rothschild nearly two years ago and learned this was the question he was eager to answer. I know what you’re thinking “this has surely been researched and already known?" Well, quite simply, it hasn’t, and certainly not in well-trained athletes.

As part of our quest to help figure out how we should be eating before exercise, I'm excited to share with you the findings from a new study from our lab that was just published, titled "Pre-Exercise Carbohydrate or Protein Ingestion Influences Substrate Oxidation...

By Dr. Dan Plews

In the Ironman community, there is a lot of talk about training intensity distribution. In this blog, I am going to cover some of the basics around training intensity distribution, which is one of the key concepts you need to navigate in building up to your race.

What is training intensity distribution?

So, before we can even think about discussing the right training intensity distribution when preparing for an Ironman, it is first important to make absolutely sure we know what the term means. Essentially, when we refer to training intensity distribution, we are talking about how much of the time we spend in different physiologically based training intensity zones. Whilst there is a range of different training zone models, the simplest and most applicable is probably the three-zone model, which is the one we use to quantify training intensity distribution. In the three-zone model, you have two training zone ‘thresholds’, which we refer to as the ...

In endurance sport, there are a huge number of supplements that are purported to enhance performance, recovery, and adaptation, with very few of these actually living up to the hype. As scientists, we tend to be very sceptical of supplements and their claims, and prefer to wait for a body of literature to emerge supporting the use of a particular supplement. However, as practitioners and athletes, we also know that waiting for the scientific literature to catch-up sometimes risks leaving you missing out on a performance aid that your competitors may have taken advantage of. In this blog, we are going to talk about antioxidant supplementation, which might be one of the most discussed supplementation regimens in endurance sport.

So, what are antioxidants? To understand antioxidants, you first have to understand reactive oxygen species or ROS. ROS accumulates in muscle during high-intensity exercise, and ROS appears to have a fatiguing effect on muscle, possibly through effects on...

As we all know, the heat is a bit of a hot topic in long-distance triathlon. Our World Championships take place in the hot and humid conditions of Kona, Hawaii, and many of us compete in hot conditions in other events around the world. We, therefore, know that we need to acclimate to heat before participating in these hot-weather events (8). A lot of athletes are also starting to use heat as a means of up-regulating regular endurance training adaptations, a bit like how we have used exposure to high altitudes to trigger positive changes (1). In this blog, we are going to discuss whether one quite practical strategy – post-exercise sauna bathing – is appropriate for use in these contexts; that is, inducing heat acclimation adaptations to improve physiological responses to exercise in the heat, and inducing endurance adaptations to improve performance in cooler conditions. Before we start it is worth acknowledging that the potential for sauna bathing to induce benefits...

By Dr Ed Maunder and Dr Dan Plews

Recently, we blogged about the importance of the lactate threshold in long-distance triathlon training and performance. As we discussed, the lactate threshold is also referred to as the ‘aerobic threshold’, or VT₁ and LT₁. In this blog we are going to discuss the importance of the second physiological threshold, commonly referred to as the ‘anaerobic threshold’, ‘lactate turn-point’, or VT₂ and LT₂ (29). We refer to this second threshold as the ‘maximum metabolic steady-state’ (MMSS), and in this blog, we will explain why.

 The maximum metabolic steady-state

 The MMSS refers to the intensity at which we transition from ‘steady-state’ to ‘non-steady-state’ metabolic responses to prolonged exercise. When we are in a metabolic steady-state, exercising at a constant-power or pace will produce stable responses; that is, muscle and blood lactate concentrations, acid-base...

By Ed Maunder and Dr Dan Plews

As endurance athletes, we spend a lot of time talking about our ‘thresholds’; “what’s your FTP?” is as ubiquitous in endurance circles as “what’s your bench?” is in strength sport. FTP – or functional threshold power – is a metric gaining increasing footing in training programming and load monitoring in cycling and triathlon. Typically calculated as 95% of an athlete’s best-effort power over 20 min, FTP is used to estimate the second physiological ‘threshold’, which defines the transition from steady-state to non-steady-state physiological responses to exercise. That is, above this second threshold – commonly referred to as the “anaerobic threshold” – physiological variables such as oxygen consumption, circulating lactate concentrations, and muscle and blood acidity cannot stabilise, which means that fatigue inevitably and progressively develops.

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Dr Dan Plews and Ed Maunder

Scientists have investigated many different strategies that may up-regulate adaptations to endurance training. One thing that the majority of these strategies have in common – e.g. training with low-glycogen availability, under heat stress, or at altitude – is that they make training harder. With low-glycogen availability you have less carbohydrate energy available and may well feel flat; under heat stress the powers and paces you achieve at the various intensity thresholds decrease as you get hotter, and at altitude, it is more difficult to get the necessary oxygen to the working muscles due to the thin air. Therefore, any greater adaptive pay off comes at some cost

One strategy that may not come at this “makes it harder” cost that has seen some attention in the exercise physiology literature is bicarbonate supplementation during training. Many of you may be familiar with bicarbonate in an acute performance context; as an...

As we enter the holiday season and festive period, I am reminded of a Journal of Physiology study published in 2013 by a group of researchers from the University of Bath in the U.K. (2). The results of this study have relevance to all of us at this time of year; whether we are training for an upcoming competition or event, or just for our health and wellness.

It is well-documented that brief periods of overfeeding - that is, consuming many more calories than we expend in our metabolism – can have negative consequences for our metabolic health. For instance, short periods of overfeeding, much as we might see over the holiday period, have been shown to impair insulin sensitivity (3) and have effects on things like adipose tissue gene expression (1). I don’t bring this up to scare you into boycotting Christmas dinner; relaxing and enjoying the holidays is a great opportunity to blow off a little of the steam that has built up in this most challenging of years. Whilst those...