|"Go slow, grow fast" - does it really work this way?|
The methodological issues are probably also part of the reason that it would be an exaggeration to say that there are only "few" studies that investigate the influence of the time under tension (TUT) on hypertrophy or strength gains - but alas, I have collected the science-crumps for you. So here you go (for a preliminary list):
Figure 1: Myofibrillar fractional protein synthesis (%/h; Burd. 2012)
In view of the pathetic load (30% of the 1RM) and the matched volume, the practical relevance of these figures is yet highly questionable. For me personally, it is thus more surprising that the difference between ...
- doing 12, 7 and 6 reps @ 30% of the 1 rep max to failure for 198±10 s 119±9 and 90±7s, respectively (SLOW condition w/ TUT of 606), and
- performing the same number of reps with the same weight, this time obviously not to failure, within 25±2s, 14±1s, and 11±1s, respectively,
- Longer TUT, greater anaerobic energy expenditure - Inspite of the fact that it appears logical that longer times under tension would be associated with increases in energy expenditure, you as a SuppVersity reader know very well that not all things that exercise and nutrition science is not necessarily logical.
In view of the overall scarcity of literature it is thus more than worth mentioning that Christopher B. Scott's 2012 study into the effects of time-under-tension and weight lifting cadence on aerobic, anaerobic, and recovery energy expenditures found that both, the anaerobic (=glyoclytic) energy expenditure and post energy oxygen consumption (EPOC) were significantly increased, when you train with a cadence of 4:1 or 1:4 and a corresponding TUT of 25s instead of 1.5:1 (TUT = 15s).
Figure 2: Anaerobic energy expenditure, post exercise oxgen consumption and total energy expenditure (all in kJ) in the low TUT (1.5:1.5; 15s) vs. high TUT trials (Scott. 2012)
In view of the fact that the majority of us are hopefully not hitting the gym to "burn calories" (learn why that's simply dumb), these findings are interesting, but of similarly irrelevant as the previously cited increases in protein synthesis in the Burd study.
- Concentric tension time is key to muscle growth -- I know that broscience dictates otherwise, but the evidence from a human study by Gillies, Putman & Bell suggests just that: It's the concentric portion of the exercise that stimulates skeletal muscle hypertrophy in response to leg presses, parallel squats, knee extensions and knee flexions in 28 healthy young women with previous strength training experience (Gillies. 2006).
Figure 3: Fiber area (µm²) of type I & II fibers before and after the 9-week training intervention (Gillies. 2006)
In view of the fact that the eccentric emphasis group did also record greater strength gains, it appears unwarranted to change your training regimen from explosive / fast concentric vs. slow eccentric movements to the "concentric emphasis" pattern with its 4s : 1s cadence that was used in the study at hand.
- Heavy and fast or "slow" and long - it does not even matter -- In 2006 and thus 6 years before the previously discussed study by Burd et al., Michiya Tanimoto and Naokata Ishii, two scientists from the University of Tokio conducted a similar, yet more realistic study which compared
Figure 4: Cross-sectional area of the knee extensor before (open bars) and after (solid bars) LST, HN, and LN exercise training for 12 wk (Tanimoto. 2006)
- a high-intensity training regimen ( 80% 1RM) with normal speed (1 s for concentric and eccentric actions, 1 s for relaxing; HN), and
- a low-intensity with normal speed training regimen (same intensity as for LST and same speed as for HN; LN)
- Burd, N. A., Andrews, R. J., West, D. W., Little, J. P., Cochran, A. J., Hector, A. J., ... & Phillips, S. M. (2012). Muscle time under tension during resistance exercise stimulates differential muscle protein sub‐fractional synthetic responses in men. The Journal of physiology, 590(2), 351-362.
- Gillies, E. M., Putman, C. T., & Bell, G. J. (2006). The effect of varying the time of concentric and eccentric muscle actions during resistance training on skeletal muscle adaptations in women. European journal of applied physiology, 97(4), 443-453.
- Scott, C. B. (2012). The effect of time-under-tension and weight lifting cadence on aerobic, anaerobic, and recovery energy expenditures: 3 submaximal sets. Applied Physiology, Nutrition, and Metabolism, 37(2), 252-256.
- Tanimoto, M., & Ishii, N. (2006). Effects of low-intensity resistance exercise with slow movement and tonic force generation on muscular function in young men. Journal of Applied Physiology, 100(4), 1150-1157.