Aims of LT (lactate threshold) training. It is training designed to enable you to run at higher intensity and therefore at a faster pace for longer periods of time before getting fatigued. It will improve performance at race distances from 10km to marathon. And it improves VO2 max readings. VO2 max is strongly correlated with improved functional capabilities, reduced risk of chronic diseases (e.g., Type II diabetes), and therefore health-span and longevity – the race of your life. Higher VO2 max is also strongly associated with lower dementia risk. In addition, running at faster speeds increases the force through your bones and benefits your bone density. Moreover, as with doing anything hard or uncomfortable, it strengthens your confidence, self-esteem, sense of efficacy and mental toughness.  So in summary it’s good for your physical, mental and brain health as well as your race performance.

How to find your LT without a lab: You have two LTs: the lower one (LT1) is the point at which you move from say walking to jogging or running at a sustainable steady state. It comprises quite a wide range of intensities before you reach its upper boundary at LT2. At these paces, you can chat with your companions, and you are not breathing heavily. It corresponds roughly to Zones 2-3 in Garmin’s 5-zone system. – i.e. Light to Moderate intensity.  Zone 3 is commonly called “Aerobic” intensity. You feel like you could do this all day. You would rate the effort as 4-6 on a 10-point Rate of Perceived Exertion (RPE) scale. You would warm up and do your long runs at this intensity. If you train by heart rate, it corresponds to roughly 60-80 % of your maximum HR. However, since most people do not accurately know their max HR (and the common formulae have high standard errors; higher for older adults), use RPE as your guide or estimate it from the max HR recorded when wearing a chest strap in a full effort 5km race or parkrun and add 2-3 beats. For example, the widely used 220-age formula predicts a max HR of 150 for me at age 70. But I have recorded 160 bpm this year in several full-effort parkruns and tough climbs on the bike. So, I work with 162 as my estimated max. Unless you’re a super-elite athlete seeking the tiniest of marginal gains, this will be a good enough estimate

But we are interested in is your upper (LT2) threshold for these sessions. It is the pace at which the concentration of lactate in the blood increases exponentially. This is the pace where you are working hard, but not at flat-out sprint speed. You will be breathing such that you can’t utter more than a few words during runs at this effort. It’s a pace and intensity you could sustain in an hour-long full effort race, i.e. a 10-mile race if you’re quick or a 10 km race if you’re a 60-minute 10km runner. It’s described as “challenging” or “comfortably hard” as distinct from “comfortable” in LT1 and “hard” if you’re above LT2. It corresponds roughly to Garmin’s Zone 4 which it terms “Threshold”. It corresponds to about 80-90% of your max HR and between 7 and 8 on the RPE scale.

How it works: Training regularly above LT2 and below your anaerobic threshold increases the intensity/pace at which your body tips from aerobic to anaerobic metabolism, thus delaying the point at which you feel like you’re running through treacle. So, it pushes up your body’s speed limit.  It does this because it improves the body’s efficiency at  clearing lactate from your muscles; increases the stroke volume of your heart, helping to push more oxygen-rich blood to working muscles;  promotes the formation of additional mitochondria and capillaries in the muscles which enhance their ability to metabolise fuel and make use of oxygen.