Making Sense of Workout Tempo: Does it Boost Muscle Growth?
In the fitness world, tempo, or the speed of your lifts, is often discussed regarding maximizing hypertrophy or muscle growth. But does tweaking your lifting tempo give you an edge? Let's break it down.
What is Tempo?
In strength training, tempo refers to the speed at which you perform a rep. It can be adjusted in two main phases of the lift: the concentric phase, when you're lifting the weight, and the eccentric phase, when you're lowering it.
Concentric Tempo and Hypertrophy
When you perform slower contractions, more cross-bridges form in your muscle fibers, leading to more mechanical tension and potentially more muscle growth. However, for this to happen, the velocity (or tempo) must slow down involuntarily, typically within the final five reps of a set. If you deliberately slow down the lifting phase before reaching this point, you may not recruit the maximum number of motor units, which are essential for muscle growth. Therefore, intentionally reducing the concentric tempo may not give you any hypertrophy benefits.
Eccentric Tempo and Hypertrophy
Slowing down the eccentric phase, or the lowering part of the rep, could lead to better hypertrophy results. Regardless of the tempo, similar amounts of force are produced in eccentric contractions, meaning you can extend the time under tension by slowing down. This extended tension can help stimulate muscle growth.
Although motor unit recruitment in eccentric contractions is slightly lower than in concentric contractions, combining them can provide greater hypertrophy benefits.
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Finding the Right Tempo
How long should the eccentric phase be? Although longer eccentric phases increase muscle tension, when the duration becomes too long (6 seconds or more), it can lead to greater fatigue, reducing the effectiveness of future sets. Keeping your eccentric contractions around 4 seconds allows for a greater time under tension while minimizing fatigue and performance loss.
In Conclusion
Modifying your weight lifting tempo can enhance muscle growth. While intentionally slowing down the concentric tempo may not offer additional benefits, reducing the speed of the eccentric phase can. Aiming for about 4 seconds in the eccentric phase provides optimal tension without causing excessive fatigue.
References:
Armstrong R, Baltzopoulos V, Langan-Evans C, Clark D, Jarvis J, Stewart C, O'Brien TD. Determining concentric and eccentric force-velocity profiles during squatting. Eur J Appl Physiol. 2022 Mar;122(3):769-779. doi: 10.1007/s00421-021-04875-2. Epub 2022 Jan 17. PMID: 35038023; PMCID: PMC8854263.
Wilk M, Stastny P, Golas A, Nawrocka M, Jelen K, Zajac A, Tufano JJ. Physiological responses to different neuromuscular movement task during eccentric bench press. Neuro Endocrinol Lett. 2018 Mar;39(1):26-32. PMID: 29803204.