Increasingly I’ve seen tempo lifting rise to prominence across social media. By tempo lifting we mean specific emphasis on eccentric and isometric components of the lift. Triphasic training help restore these methods to popular consciousness. There is however in peoples attempt to compress methods a trend towards eccentric/isometrics often programmed like 3:2:0:0 or something similar. Eccentric/Isometrics may seem like a genius two birds one stone type of scenario but often winds up being all stones and no birds. Why?
The reason is simple quality of contraction type. The true benefit of eccentrics and isometrics lies in the quality of contraction (highest recruitment rates and coordination). What effects contraction quality? Simply put fatigue. Good quality Eccentric and isometric contractions are enormously fatiguing. Its why triphasic training is sequential, so the quality of each contraction type is emphasised throughout each block.
You can combine contraction types on a more macro level. So, a day with eccentric focus and a day with isometric focus within the same week for instance. But combining them on the same day is where the quality issues start to creep in. Heavy eccentrics are structurally fatiguing, whereas heavy isometrics seem to be centrally fatiguing so surely the two shouldn’t overlap too much?
Well the rate limiter here is ultimately what the Alactic energy system can provide. Its why well-planned heavy eccentric and isometric work generally keeps the intended focus elements under 10 seconds (hypertrophy is a different beast). Supramaximal reps are often less than 10 seconds, multiple reps for conventional triphasic sets total eccentric/isometric stress usually less than 10 seconds and often no more than 15 seconds. By combining these two things fatigue becomes governing factor and the attainment of high-quality contractions diminishes past the first few reps.
You can combine them, try have you cake and eat it but your results will be suboptiomal.
Ditch the eccentric, isometrics and focus on one or the other.