• 24 MAR 14
    • 0

    IM-Mallorca_70.3

    Although now known as the most informative and accurately trackable performance parameter in cycling (and running), one of the most useful and direct applications for Maximal Lactate Steady State values are in Time-Trial, Duathlon and Triathlon, for a multitude of physiological reasons.  Recently, I had the pleasure of profiling the lactate kinetics of three up-and-coming youthful Ironmen. This was a prime opportunity for them to see exactly how they had fared with their Winter training and what sort of shape they were in with only two months to go before IM Mallorca, to focus on specifics and get some more important gains in time for race day.

    All three guys were of similar age 24, 23 and 25, but different weights (79, 87 and 95kg), height (182, 193 and 196cm) and body fat (approx. 18%).

    As most of you are aware that 70.3miles is the distance of a half ironman, comprising of a 1.2-mile (1.9 km) swim, a 56-mile (90 km) bike ride, and a 13.1-mile (21.1 km) run. So, as running is naturally a more anaerobic exercise than cycling (due to the greater muscle mass required to carry the body over distance), preserving as much glycogen for this part of the race is key to success in terms of pacing to your potential limits. Clearly though, making sure you have used enough energy during the cycling time-trial section to gain time on competitors who may be weaker at cycling is also crucial. This is where setting your race pace comes into play and having a power meter. The first lactate turning point, the work-rate at which the anaerobic system is first engaged more significantly and greater amounts of glycogen are used ‘inefficiently’ as fuel to supplement more efficient ‘aerobic’ fuelling from fat and glycogen is dependent on the muscle firing patterns and composition in the skeletal muscle. This turning point is inherently associated with your lactate threshold, yet more subtly defined. Training the lactate threshold (MLSS) will positively affect the first turning point, although this is not reciprocal.

     IM_graph_I

    No-one has enough glycogen stored in their liver and muscles to last an approximately 3 hour effort at their threshold pace. So to preserve the depletion of these stores for running the half-marathon, maintaining an optimal pace at which the lactate pool works optimally for the effort involved and further nutritional supplementation are necessary for peak performance.

    Looking at both the table and graph we can see three different types of lactate profiles and rider parameters with a general increase in training history for Tri 1, Tri 2 and Tri 3 (0-2, 2-5, and 5-10 years) and volume of training (5-9, 12-15, 15-20hrs/week) respectively. Lactate accumulation for Tri 1 is quite steep and hits a higher peak value than the others. This is both because his aerobic conditioning and oxidative capacity of his muscle fibres to sustain work-rates between 240-260Watts is much less than at lower intensities. Beyond 280Watts, lactate is obviously starting to accumulate uncontrollably, if not sooner than this. This athlete also uses his training time to focus on shorter intense efforts (which has resulted in an increased blood lactate clearance compared to the other two athletes), whereas greater exposure at moderate intensities away from the threshold ‘dead zone’ ie 200-240Watts and 260 Watts higher would provide much more efficient returns on aerobic conditioning for the same discipline, as we see for the other two tri-athletes.

     IM_table_I

    Tri 2 has undertaken more training than Tri 1 as we see improved lactate tolerance at ‘baseline’ intensities 200-260 Watts and a lower peak lactate value as the lactate system demonstrates better tolerance. However a step does exist around the habitual lactate threshold zone (260-300Watts) before a rapid accumulation. This suggests that the athlete’ threshold is working quite close to his maximal aerobic capacity and should look to improve this through increase skeletal muscle oxidative efficiency, through regenerative strength exercise and neuromuscular conditioning.

    Tri 3 is clearly the strongest cyclist (and biggest) of all three having trained the most, we can see that his aerobic conditioning is very good with very low lactate concentrations at baseline intensities up until 300Watts. However there is a possible ‘step’ in his profile just around his threshold level, where he prefers to spend too large a proportion of his time. We can see that his peak lactate value is lower than Tri 2 but more importantly how his lactate accumulation over the higher intensities has slowed down, suggesting he is spending significant proportions of training at these intensities and working on strength conditioning to sustain 360-400Watts.

     IM_table_II

    In the table above I have stated recommended race powers/ heart rates during the 90km TT to preserve glycogen depletion for the half marathon. Although I assume further gains in performance will be achieved before race day, and these recommendations should be revised.  The athlete should adjust their pace to somewhere around these values in line with perceived effort for optimal use of energy. If all the athletes are able to pace the 90km well enough by power/ heart rate and feel then applying the same principles to make the most of their half-marathon lactate threshold pace and the amount glycogen available (without being able to eat) for the last part of the race without blowing up. Split times on steady-state endurance sports are extremely helpful for ideal pacing strategies, but combining three disciplines makes this very difficult.

    Relying on lactate kinetics gives athletes a more superior parameter to work with, with more realistic ‘expectations’ of race success and push their bodies to the true limit.

    Don’t forget to get aero!

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