12 Weeks of Sustained vs. Explosive Contraction for Muscle Mass: Which is Better?

12 Weeks of Sustained vs. Explosive Exercise: Which is Better for Muscle Mass

By: Robbie Durand

In the world of bodybuilding, there is much debate as to what the best repetition speed is best for muscle mass. Some bodybuilders prefer a slower and controlled repetition speed whereas other prefer a faster pace repetition speed. There have been top bodybuilders that have gained an incredible amount of muscle mass with both fast and slow pace contractions. Explosive lifting rates have been found to produce significant increases in both maximum and explosive strength. For example, if you watch football players and track athletes in the gym, they focus on speed. Many studies have found that training styles such as super slow training to be inferior to training with a faster-paced repetition speed. The only athletes that use super slow training are bodybuilders because no athlete in their right mind would want to move slowly. There have not been many studies that have compared explosive style repetition speeds to controlled, slower lifting speeds. Researchers set out to examine whether slow and controlled vs. explosive training was best for muscle mass. The subjects in the training groups performed four sets of 10 unilateral isometric knee extension contractions three times per week for 12 weeks.

43 young, healthy males were randomly allocated into either:

-an explosive training group (performed each repetition by contracting as fast and hard as possible for around 1 second),

– a sustained training group (gradually increasing to 75% of maximum voluntary torque before holding for 3 seconds).

The results were fascinating, to say the least for both fast and slow and controlled lifting.

Muscle Strength

For muscle strength, both slow and explosive training increased muscle strength but explosive improved contractions at all time points (50, 100 and 150ms) by 17 – 34% but sustained contractions only improved knee extension torque during explosive contractions in the late phase by 12%. So explosive training increased muscle strength thru the entire range of the movement whereas the slow and controlled increased strength only in the later phase of motion. The researchers stated, “In this case, brief explosive contractions up to a high loading magnitude appear to be an efficient means of increasing maximum strength without the requirement for sustained muscular contractions. Furthermore, if loading magnitude is the primary stimulus for maximum strength gains, then it is possible that even higher loading magnitudes than those employed in the current study, which may be achievable during very short contractions, could provide an even greater stimulus for enhancing maximum strength. ” So if you are an athletes and want to improve competitive sports movements, then clearly explosive training movements are going to be more beneficial.

Muscle Size

For muscle size, despite the faster lifting speed being better for muscle strength, the slow and controlled lifting group had greater increases in muscle mass. In fact, the slow and controlled group had three-fold greater hypertrophy after slow and controlled than fast and explosive. Slow and sustained contractions increased total quadriceps volume by 8.1% whereas explosive training increased muscle volume by 2.6%. Slow and controlled training indicates that this adaptation is dependent on loading duration. Meaning the muscle lifted slow and controlled had greater loading over the workouts. The researchers found that training-specific functional changes that appeared to be due to distinct neural and hypertrophic adaptations. Explosive training produced a wider range of functional adaptations than slow and controlled training, and given the lesser demands of explosive training, this type of training provides a highly efficient means of increasing function.

Key Points: If your looking to increase muscle strength than lifting fast and explosive seems to be the way to go, but if you are looking to pack on muscle than lifting with a slower and controlled manner seems to be most beneficial.

Training specific functional, neural and hypertrophic adaptations to explosive vs. sustained-contraction strength training, by Balshaw, Massey, Maden- Wilkinson, Tillin & Folland, in Journal of Applied. 2016