Our most recent trait release highlights how variants in the MCT1 gene can affect how efficiently we clear the byproducts of lactic acid from our bloodstream during exercise.

Lactic acid is produced during anaerobic respiration - the process whereby cells break down glucose to create energy in the absence of oxygen. Lactic acid then dissociates (or ‘splits ups’) into lactate and a hydrogen ion, both of which are cleared from the bloodstream by the transporter protein MCT1.

Contrary to popular belief, it is not lactic acid or lactate itself that causes muscle fatigue during exercise, but rather the buildup of acidic hydrogen ions. Lactate can, in fact, prove beneficial for exercise performance as it can be reused to produce energy via alternative systems, as well as enhance muscle growth through the activation of related genes, including IGF-1 and mTOR.

The rate at which we clear lactate and hydrogen ions during exercise is influenced by our activity levels of the MCT1 protein. Variants of the MCT1 gene associated with greater MCT1 protein activity enable carriers to clear lactate and hydrogen ions at a faster rate, allowing them to exercise at high intensity for longer periods before fatigue sets in.

Now that we understand the uses of lactate and MCT1 on muscle building and exercise performance, here are some recommended training methods to help you maximise the effect of both.

1. Supersets

Supersets involve performing two exercises consecutively, with minimal or no rest in between. This can be carrying out two exercises for the same muscle group (e.g. bench press followed by chest flyes), or antagonistically, targetting opposing muscle groups (e.g. bicep cable curl followed by a tricep cable push down).

Carrying out supersets results in an increase in metabolic stress, which is caused by a build-up of metabolites such as lactate and hydrogen ions. This increase in metabolic stress can promote hypertrophic signalling, aiding muscle growth.

For those that clear lactate more quickly than others, using the superset method can allow these individuals to gain the hypertrophic benefits of lactate accumulation. People who don’t have the ability to clear lactate as quickly can still benefit from this training technique if the supersets are carried out towards the end of their workout. This way the increased lactate accumulation won’t have a detrimental effect on the performance of other exercises in the workout.

2. '2 plus 2 rule'

The '2 plus 2 rule' is a training principle that guides the effective progression of a training plan. If you can complete 2 or more reps during the last set of your workout than you were aiming for in two consecutive workouts, then it is time to increase your load to induce continued training adaptations. These adaptations include increased muscle strength and size, but also an improved ability to clear lactate from the muscles.

For example, if you are aiming to complete 3 sets of 10 reps at 40kg on the flat bench press and are able to complete 12 reps on the last set of two consecutive workouts, then it is time to add some more plates to the bar and bump that weight up!

Having greater knowledge of when you need to increase your training load is beneficial to help you build muscle more effectively. If you continue to work using a load that you can easily complete 3 sets of 10 repetitions with, then you wouldn’t experience continued muscle growth.

This method can be particularly useful to help improve your lactate clearance, ensuring that you can work for longer with minimal fatigue.

3. Blood flow restriction training

Blood flow restriction training is where you minimise the blood flow to the specific muscle that you are working on by using an inflatable cuff to decrease your blood pressure. You then carry out low-intensity exercise (20 - 50% of your 1RM).

Restricting the blood flow to your working muscles reduces the amount of oxygen that reaches those muscles. Lower oxygen levels result in an increase in metabolic stress as lactic acid accumulates, leading to increases in its byproducts: lactate and hydrogen ions. Similarly to the supersets, the build-up of lactate and hydrogen ions increases metabolic stress which helps increase muscle size.

Blood flow restriction training would be better suited to individuals who regularly carry out resistance training and is beneficial for those who have a better ability to clear lactate, to ensure that the buildup of lactate doesn’t have a detrimental effect on performance.

4. Eccentric movements

Eccentric contractions occur when the muscle is lengthening, rather than shortening. If you imagine a bicep curl, when you lift your arm up to your chest the bicep muscle gets shorter, while when you lower your arm back down the muscle gets longer. This lowering motion is the eccentric contraction.

Slowing down this eccentric phase of the rep can be beneficial for people who have better lactate clearance. The muscle is put under greater tension, which can result in metabolic stress and a greater increase in muscle growth.

People who have reduced lactate clearance due to their MCT1 gene variant should minimise the use of slow eccentric contractions. These contractions could lead to detrimental impacts on performance following their use and may cause prolonged feelings of fatigue due to slower lactate clearance.

Summary

Lactic acid is often seen as a negative product of exercise; the cause of fatigue and muscle soreness. However, we can see that there are a number of methods that allow you to utilise the accumulation of its byproducts to promote the necessary metabolic conditions to encourage muscle growth and improve exercise performance.

Using some of these training methods can help you train smarter, achieve greater muscle gains, and continually push your workout capacity.