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Darkhorse · 07-02-2005, 07:47 AM

Tabata Compared
Anyone who has tried them both will tell you that 30 seconds “all-out” with 4 minutes rest is a walk in the park compared to the Tabata protocol. Four minutes allows almost complete recovery—and time to renew enthusiasm for another very hard 30 seconds. The heart of the Tabata protocol is the 10-second rest interval, which allows partial recovery at best. That’s the idea; incomplete recovery makes each rep harder than the last, and brings you to the point of exhaustion on the last rep. Seven or eight reps and you’re done, literally.

The longer rest period in the study under discussion was probably a drawback in terms of effectiveness. On the other hand, the three-day-a-week frequency was very likely an advantage. (The Tabata protocol was done Monday through Friday with no rest days between exercise bouts.)

As noted above, the 20:10 work-to-rest ratio in the Tabata study produced substantial improvement in both aerobic and anaerobic work capacity, while the 30-second:4-minute ratio failed to produce improvement in either category. As explained in article 10, the reason almost certainly lies in the degree of overload. The Tabata protocol overloaded both aerobic capacity and anaerobic capacity to the max, while the work-rest ratio in the present study--the much longer rest periods in particular--probably produced a sub-maximum overload.

In a later study, Dr. Tabata compared the original protocol with an interval program very similar to one under discussion. Each subject did 4-5 bouts of 30 seconds, with 2-minute rest periods, to exhaustion. Tests showed that the 20-second intervals, with 10 seconds rest, overloaded both aerobic capacity and anaerobic capacity maximally, while the longer interval protocol, with two-minute rest periods, did not. In both respects, the stress produced by the second protocol fell well short of maximum.

But why? Why did the original protocol stress both aerobic and anaerobic capacity maximally, when the more intense (200% VO2max vs. 170%) and longer (30 seconds vs. 20) bouts of the second protocol did not? Dr. Tabata and his colleagues believe the key factor was the difference in the rest periods.

The relatively long 2-minute rest periods allowed oxygen uptake to fall considerably and, therefore, when the next exercise bout started there was a delay before the oxygen uptake increased and began again to approach maximum. On the other hand, the short 10-second rest periods allowed only slight recovery, and therefore oxygen uptake increased in each succeeding bout, reaching maximum capacity in the final seconds of the last bout. The same was true for anaerobic energy release. The 2-minute rest periods stopped the buildup of lactate and allowed the resynthesis of phosphocreatine (see article 7, Diet & Nutrition, on creatine) to occur. Again, the short rest periods in original protocol caused the oxygen deficit to continue building from rep to rep, reaching maximum anaerobic capacity at the end of the exercise.

Almost surely, that's why the current study failed to show improvement in aerobic and anaerobic capacity. The 4-minute rest periods allowed almost complete recovery and maximum stress was never achieved.

On the other hand, the one or two days rest between workouts probably gave the current study a leg up on the original Tabata protocol. The researchers believed that the rest days would be an important advantage. “The importance of rest days between sprint training sessions was emphasized in a recent study that showed that peak and mean power elicited were unchanged after 14 consecutive days of sprint training; however, when subjects performed the same number of training sessions over 6 weeks, with 1-2 days of rest between training sessions, power output improved significantly,” they wrote in the study report. “Although numerous mechanisms could potentially be involved, the importance of rest days between training sessions may be related in part to the fact that strenuous exercise leads to inactivation of cation pumps, and it has been speculated that up to several days may be required for normalization of sarcoplasmic reticulum Ca2+ pump function.” Simply put, it takes a day or two for muscles to recharge after very intense exercise.

So, it’s possible that Dr. Tabata and his colleagues could have achieved even better results by allowing their athletes a day or two to recover between workouts.

Another advantage of the interval protocol under discussion is that more people are likely to be willing to do intervals with 4-minute rest periods than with 10-seconds. Both protocols are obviously hard, but the less demanding regimen probably has wider appeal. It might turn more couch potatoes into gym rats.

Words to the Wise
As noted above, interval sprints are not for everyone--certainly not for people just getting started or those with health problems. If you have doubts, by all means talk it over with your doctor.

Frankly, I enjoy high-intensity intervals; they're challenging and leave no time for boredom. Not all the time, however. I make it a point to vary the work-rest ratio and cycle my training. I don't train all-out all the time.

Generally, short hard intervals with long rest periods are recommended to improve anaerobic capacity; and repetitions with short rest periods are suggested to overload the aerobic system. The Tabata research and the current study suggest that intensity--not volume--is the key to success.

It’s important to start a new regime at a manageable pace and ramp-up over time as your condition improves. When you top out, change the plan and start over.

Train smart and keep in mind that you usually get out of a program about what you put into it. That doesn’t mean more is better, however. As the current study demonstrates, stress and rest are both important.

Good training. :cool: