Lose fat by programming short rest intervals between work sets to increase growth hormone response and raise blood lactate concentrations. Short rest intervals and a higher work-to-rest ratio will produce a higher metabolic response to exercise to help you lose fat, but this will also result in lower power output. Therefore, if you are training for a sport, you will want to include exercises with longer rest intervals to be able to exert peak power and crush your opponents.
New research in the Journal of Strength of Conditioning Research reminds us how to program rest intervals to achieve performance and body composition goals. This study tested the effect of three different training schemes on muscle power production and blood lactate response in the squat. The 3 rest/loading schemes were as follows: a short-rest condition of 12 sets of 3 reps with 27 seconds rest between sets; a long-rest condition of 12 sets of 3 reps with 60 seconds rest; and a long-rest large-rep condition of 6 sets of 6 reps with 60 seconds rest.
Results showed that the long-rest condition of 12 sets of 3 reps allowed the athletes to produce significantly more power than the other two conditions. This is not surprising since each set required a smaller amount of work and allowed for more complete recovery and restoration of muscle creatine content. Since power output is the product of the amount of force that you can exert and the velocity (or speed) with which can exert it, power will be at its peak when you are fully recovered and have optimal short-term energy stores.
We also know that high speed movements produce greater neural adaptations, which will allow you to produce greater power assuming you have corresponding strength to go with that speed. Generally, complete recovery of the neuromuscular system takes longer than it takes to replenish energy stores like creatine, meaning that for peak power output, rest intervals need to allow for repair of central nervous mechanisms.
The study also showed that blood lactate concentrations after the workouts were higher after the long-rest large-rep (60 seconds, 6 X 6) and the short-rest (27 seconds, 12 X 3) conditions. Greater blood lactate buildup indicates the workout was metabolically more taxing and will result in more growth hormone being release. Growth hormone enhances fat burning in the body, and the greater metabolic cost of these two workouts will be better for fat loss and body composition. But, you won’t train power as well, which is the reason you can only train to achieve one goal at a time.
Take away from this study the understanding that to achieve peak power for sports, you need near complete recovery between sets (more sets with fewer reps are best). To lose fat, use shorter rest and a large volume—you’ll burn fat and boost growth hormone, avoiding the catabolic, muscle-degrading environment that comes with aerobic training.
Paulo, C., Roschel, H., et al. Influence of Different Resistance Exercise Loading Schemes on Mechanical Power Output in work to rest Ratio—Equated and Nonequated Conditions. Journal of Strength and Conditioning Research. 2012. 26(5), 1308-1312.