Muscle growth can occur with a large range of repetition speeds from 0.5 seconds (fast) to 8 seconds (slow). The full recruitment of all muscle fibers by taking sets to failure stimulates muscle growth rather than the repetition tempo or TUT.
TIME UNDER TENSION MUSCLE GROWTH: FACT OR FICTION
TIME UNDER TENSION SUMMARY
- Studies have found similar muscle growth despite protocols with greater time under tension (TUT).
- Muscle growth can occur with a large range of repetition speeds from 0.5 seconds (fast) to 8 seconds (slow). Slower repetitions result in a reduction in training volume.
- Studies have found similar muscle growth despite protocols with greater TUT.
- The full recruitment of all muscle fibers by taking sets to failure stimulates muscle growth rather than the repetition tempo or TUT.
TUT TRAINING: TIME UNDER TENSION MYTH OR FACT?
What does TUT mean? Time Under Tension (TUT) is defined as the amount of time a muscle is contracting by timing the duration of the sets and reps. TUT is highly controversial because some studies have found increased muscle growth with a greater time under tension workout, while others have found no difference.
SLOW REPS VS FAST REPS: DO THEY MATTER FOR MUSCLE GROWTH?
If you raise and lower the weight slower, more continuous tension is placed on the muscle. Sounds reasonable, but unfortunately, the time under tension hypertrophy claims don’t hold up to the science. The muscle-building stimulus does not strictly rely on the length of each set but on the amount of volume and whether sets are taken to failure each set.
DOES TIME UNDER TENSION BUILD MUSCLE?
One would expect greater time under tension muscle growth, but research does not support this. For example, one study compared a bodybuilding protocol using (3 sets of 10 repetitions), whose TUT was 30-40 seconds, to a powerlifting protocol (7 sets of 3 reps) with a TUT of 9-12 seconds, which resulted in similar muscle growth.[1]
IS TIME UNDER TENSION A MYTH?
In a 2019 study, subjects who trained to failure and were assigned to a high rep (20-25 repetition maximum) gained similar increases in muscle to those using low reps (6-8 repetition maximum); however, the heavy weight groups had a slightly greater increase in muscle mass.[2] Another interesting finding was that the time under tension was 60-75 seconds for the high-rep group. In contrast, the strength group TUT was 18-24 seconds. Even though there were differences in TUT for both groups, muscle growth was similar.
TIME UNDER TENSION FOR MUSCLE GROWTH
A 2020 study reported that when one group lifted with a 2-second concentric and a 2-second eccentric phase compared to a group that lifted at a much quicker repetition speed resulted in similar increases in muscle growth.[3] The author concluded, “When the total work volume is identical, lifting at a self-selected repetition speed, regardless of the tempo, resulted in similar increases in strength and muscle.”
Another 2021 review of the literature concluded that slow lifting movements did not enhance muscle growth. The author concluded that, despite lowering the weight slowly, which increases time under tension, the lower amount of weight utilized often led to a lower total training volume. It was concluded in the review that neither isolated fast nor slow movement tempos are more effective for muscle hypertrophy. Based on the research, lifting tempo has a minor effect on muscle growth when sets are taken to failure.
TUT DOES NOT MATTER WHEN SETS ARE TAKEN TO FAILURE
Researchers investigated the effects of two training protocols with different repetition durations and their effect on muscle growth and strength. One drawback was that the subjects were untrained. One group trained with one leg for 2 seconds (1 second concentric and 1 second eccentric) and the other leg for 6 seconds (3 seconds concentric and 3 seconds eccentric) for 14 weeks.
Both protocols performed 3-4 sets with 50-60% of a 1-RM. All sets were taken to complete failure. The 6-second duration group had a longer TUT than the 2-second group. TUT was 25% larger than the 2-second protocol (i.e., 43 seconds vs. 30 seconds). The 2-second group was able to complete more repetitions than the 6-second group. The 2-second group did approximately double the repetitions of the 6-second group (14 vs. 7 seconds).
At the end of the study, both groups had similar increases in dynamic muscle strength and muscle growth. Thus, the researchers reported a person could do faster repetitions (1 second up, 1 second down) with more repetitions to failure or use a slower repetition speed (3 seconds up, 3 seconds down) with a longer TUT and gain similar results in increases in muscle mass.
In conclusion, despite different training volumes and different TUTs when sets are taken to complete failure, similar increases in muscle growth occur. This is in line with previous research, which shows that the repetition speed is less important when sets are taken to failure.
SUMMARY
Based on the research, muscle growth can occur with a large range of repetition speeds from 0.5 seconds (fast) to 8 seconds (slow). The full recruitment of all muscle fibers by taking sets to failure stimulates muscle growth rather than the repetition tempo or TUT.[6]
REFERENCES
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