One of my articles from earlier this week discussed how to use rest intervals to maximize strength over the course of a set. Greater ability to lift heavy weights over the course of a workout means greater strength in the long run. In this particular study, it was the case that longer rests were better, especially four and five minute rests, and that one minute rests were no good. This makes good intuitive sense, but it isn’t the whole picture.
The thing that made that study unique was that it was amongst the first of its kind to look at strength. Similarly, we are in the dark about how to rest for the expression of power. You might wonder why we would need more research for power if the strength study gave us solid, intuitive results. Well, in a study this month in the Journal of Strength and Conditioning, researchers wanted to take a look at the proper rest intervals for power, just for good measure. It never hurts to be too thorough. And it’s a good thing they did, because the results are surprising.
The difference between strength and power can be confusing. Strength is more or less the amount of force you can exert. In other words, the heaviest weight you can lift is an expression of maximal strength. Power is the rate (speed) at which a force can be moved. Part of the confusion is that the sport most concerned with strength is called powerlifting. Strength is a component of power, but not the other way around. As far as power goes, if you can lift more weight at the same speed, your power has gone up, and if you can lift the same weight at a faster speed, again, your power has increased.
Because strength and power are different, they don’t always respond the same to the adjustment of variables. For example, you might think a heavy weight is required for the most power, just like it is for strength, but in reality the greatest power output generally comes from relatively light weights. Indeed, in this study, the researchers used seven sets of jump squats per workout with an increasing load. The squats were performed from unweighted all the way up to 60kg in 10kg increments. The greatest power output was with just the bodyweight alone.
The surprising thing about this study is that when the researchers compared one, two, three, and four minute rests between sets, they found no difference. One would think rests as short as one minute would cause performance to decline in the later sets at least, much like it did with the upper body strength of the other study, but this was not the case for power output. The differences between the groups were either too small to be statistically relevant or unclear, perhaps due to the small number of participants.
In the end, the researchers deemed it unimportant which rest period length is used for three rep maximal power jump squats at various loads. This seems too surprising to be completely true, but for now we can say one thing: power definitely reacts differently to rest period length than strength.
References:
1. ML Nibali, et. al., “Influence of rest interval duration on muscular power production in the lower-body power profile,” Journal of Strength and Conditioning, 27(10), 2013.
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