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Intense training versus volume training

A new German study confirms that increasing intensity works better than upswings in volume

For years we’ve been preaching in these pages about the merits of cranking up the intensity of your training rather than pressing the high-volume button. That philosophy is based on an avalanche of research showing that high-intensity work is best for boosting VO2max and economy, on clear evidence that upswings in volume offer diminishing performance returns, and on Peter Snell’s classic research contrasting high-speed interval work versus more moderate tempo-type training, which demonstrated clear advantages for the former.

Now a new study from Germany chronicles exactly what happens to experienced athletes when they raise either the intensity or volume of their training, and again the results support the intensity strategy.

At the University Medical Hospitals in Freiburg and Ulm 17 experienced runners boosted their training mileage dramatically over a four-week period. Twelve months later the same runners undertook a major increase in their training intensity while holding mileage at a reason level (‘Unaccustomed High-Mileage vs Intensity Training-Related Changes in Performance and Serum Amino Acid Levels,’ International Journal of Sports Medicine, vol. 17(3), pp. 187-192, 1996).

During the four-week, increased-mileage period, the runners logged about 50 miles the first week (their usual volume), stepped up to 70 miles the second week, zoomed to 85 miles the third week, and reached a lofty 105 miles during the fourth and final week (no post-training orthopaedic surgeries were reported). Only 2.5-3.5 weekly miles were reserved for interval work, because 93-98 per cent of total miles were run at a very moderate pace. For training buffs, the actual speed of this moderate running was ’80 per cent of the velocity associated with a blood lactate level of 4 mmol/litre’. Why did the Germans use 4 mmol/litre as a training benchmark? Many scientists (especially German ones) believe that 4 mmol/litre represents lactate-threshold intensity and peg all training paces at some percentage of that. It’s a bit like using a heart monitor to guide training, except that lactate, not heart rate, becomes the dictator of what you do when you train.

During the four-week, increased-intensity period (which took place one year later), the runners’ training volume stayed at about 38-50 miles per week, but average training speed rocketed. That was because 400-metre intervals (completed at a tempo of about 70 seconds per 400) increased from just one interval the first week to six intervals the second week, eight reps the third week, and 4200 metres (10.5 intervals) during the fourth week.

Along the same lines, 1000-metre intervals, conducted at 107 per cent of lactate threshold (4 mmol/litre) pace soared from four intervals the first week to six the second week to seven the third week and nine during the fourth week.

The volume of tempo running at just about lactate-threshold (4 mmol/litre) speed roughly doubled during the period, from 5-7 to 8.5-10 kilometres per week between weeks one and four. Note that during the fourth week, the runners completed a total of 10.5 400m intervals, nine 1000m intervals, and 10K of tempo running. Meanwhile, long-distance running at moderate speed decreased from 85 per cent of total miles to just 73 per cent of the total.

Higher intensity wins
Both of these training periods – increased mileage and increased intensity – represent what scientists and coaches like to call ‘crash cycles’ of training. not because athletes are doomed to crash and burn up shortly after they complete them but because they involve a big explosion in a key training variable. However, the two crash cycles studied by the Germans produced much different effects on performance. Basically, the increased intensity led to improvements in a number of performance variables, while the higher-mileage period stagnated or hurt performances.

For example, at the end of the four weeks of higher-intensity training, runners improved their running velocity at a blood-lactate level of 2 mmol/litre (roughly marathon pace) from 3.99 to 4.66 metres per second (eg, from 6:43 to 5:45 per mile)! They also increased their speed at 4 mmol/litre (approximately 15K pace) from 4.58 to 4.89 metres per second (5:51 to 5:29 per mile). Total distance covered during a very rugged incremental treadmill test also rose from 4.59 to 4.82 kilometres. Overall, the changes amounted to improvements in performance of from 5 to 17 per cent.

Please note that the biggest performance uptick (17 per cent) associated with increased-intensity training occurred at 2 mmol/litre or roughly marathon pace. The change in marathon tempo as a result of upgraded intensity was truly mega – almost one minute per mile – yet coaches and runners continue to trumpet the merits of high-mileage training for the marathon. In this German investigation, mileage remained at 40-50 miles per week, yet MAJOR gains in marathon potential were attained, all because of enhanced INTENSITY of training.

Meanwhile, the increased mileage programme didn’t do much. In fact, endurance during the treadmill test actually decreased by 6 per cent from 4.73 to 4.43 kilometres. Running speed at 4 mmol/litre of lactate stagnated, heading neither north nor south. Only velocity at 2 mmol/litre improved slightly, inching up from 4.16 to 4.31 metres per second (6:26 to 6:13 per mile), a 3.6 per cent gain (contrasted with the 17 per cent gain after the high-intensity period).

Blood and the amino acids
The German scientists also took a close look at how the runners’ bodies responded to the crash cycles. Increased volume training produced two unwelcome changes – a drop in the number of white cells in the blood (this didn’t happen during the high-intensity training) and a downward slide in haematocrit (the percentage of the blood made up of red cells). However, haematocrit also dropped in the increased-intensity group, as did blood-haemoglobin concentrations. It’s likely that the decreases in haemoglobin and haematocrit were not caused by a decreased production of red blood cells but by an expansion of blood plasma – a change that often occurs when training is toughened.

The German investigators were especially interested in the runners’ blood amino-acid levels, primarily because research has shown that amino-acid concentrations have an effect on what is called ‘central fatigue’ (exhaustion during exercise that originates not in the muscles or heart but in the nervous system). Many scientists believe that during prolonged exercise an athlete’s muscles begin chewing up branched-chain amino acids (leucine, isoleucine and valine) for energy at increased rates. At the same time, another important amino acid – tryptophan – is ‘kicked off’ its preferred attachment points with molecules of albumin floating around in the blood, displaced by the free fatty acids which flood the blood during exhaustive efforts.

That may not sound important, but as it turns out tryptophan can be converted in the brain to serotonin, a chemical that tends to produce drowsiness and a sense of fatigue. Normally, branched-chain amino acids would limit tryptophan’s passage into the brain from the blood, but as the branched chains become depleted, tryptophan has carte blanche to enter the brain and create mischief.

This increase in tryptophan and lowering of branched chains might produce fatigue during a long run like the marathon, and some scientists have also speculated that it could be a chronic thing associated with overly heavy training – and thus might be a key aspect of ‘overtraining syndrome’, a malady which can grip athletes with tiredness so numbing that they feel unable to carry out workouts or move at usual speeds in races. The Germans were keen to find out which programme – increased mileage or increased intensity – would be more likely to overturn the amino- acid applecart.

What they learned was that amino-acid concentrations decreased by about 6.5 per cent after the mega-mileage training but increased by 8.8 per cent following improved intensity. Valine, leucine and isoleucine levels didn’t change one bit in either group, and free tryptophan increased significantly only after higher-intensity training, yet the higher-mileage, not the higher-intensity athletes were the ones who had overtrained. Higher-mileage runners complained of extreme muscle stiffness and fatigue, while high-intensity harriers reported silky muscles, high energy levels and of course superior performances.Thus the amino-acid shift does not seem to be a reliable marker of overtraining.

So what’s the final word? You get more bang for your buck when you enhance the intensity of your training rather than shooting for more volume. The German study shows that performances at high intensities (during the treadmill test to exhaustion) and also at approximately 15K and marathon speeds are uplifted by such efforts, even though the linkage of ‘marathon’ and ‘high-mileage training’ has been permanently branded on to most coaches and runners’ minds. You’ll run your best marathon, or 10K, or 5K, or mile, when you’re the most fit, not when you’ve run the most miles, and optimal fitness occurs when you reach a reasonable mileage level and then progressively crank up your training intensity.

Owen Anderson

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