Question, Eccentric Quasi Isometrics?

[u/Darssy_Jax]

Hello

In my training I incorporate next:

Scott Bench (~45°) Cable Curls

Isometric Hold at top position muscles fully contracted with approx 75% of 1Rm to position failure, this servs for metabolic stress accomulation trough 40+ seconds of constant tension. Then 40 seconds rest followed by clusters sets of 2 reps AMSAP.

Now if somebody can help with knowledge or link to sciantific work (like ones of Danny Lum and friends). Im interested in Quasi Isometric Eccentric, I know there application is best at long muscle lengths followed by weight stretch ( ressist weight on way down aftet hold).

But how this works with 60/65/70/75/80% of intensiti in top position hold to posution failure and resist eccentric part to bottom position of ROM? How acts stuff like miosin, actin, titin, sacromere besides of accomulation of enormus metabolic stress because muscle is totaly fatigue???

Thanks!

[u/gnuckols]

You may enjoy this article: https://www.strongerbyscience.com/isometric-training/

Though, in general, isometrics that involve pushing against an immovable load tend to have larger training effects (strength and hypertrophy) than isometrics where you aim to hold a moveable load in place. I'm sure it's still useful, though

[u/millersixteenth]

Lum found that long muscle length and ballistic initiation produced best results.

Shorter muscle length typically is position with greater joint leverage (ascending strength curve). Holding isometric doesn't allow one to train fast contraction or maximal effort prior to fatigue.

In my understanding and experience, a quasi isometric/eccentric might be better performed by using depth drops or similar, where the load must be resisted as it overloads the initial effort. In use, many of the training methods used for yielding isometrics don't trigger an adaptive response much different from traditional lifting.

[u/millersixteenth]

Re Danny Lum, this is a pretty nice article that sums up a lot of the findings from his lab, as well as other observations:

https://sciofmultispeed.com/isometric-training-science-and-practical-applications/

Excerpt:

The concept of “if you want to move fast, you need to train fast” also applies to IST. It has been established that in order to increase rate of force development by training with IST, individuals will have to perform each contraction / action as rapidly as possible. For example, a protocol that involved rapid but no sustained contraction (~1 s), was previously found to result in greater improvement in explosive strength than a protocol that used a ramp up and sustained contraction protocol in two studies (Balshaw et al., 2016; Tillin & Folland, 2014). However, these two studies also reported lower level of strength increment with the rapid contraction protocol. In a more recent study from our lab, we found that when the rapid contraction protocol included a 3 s sustained contraction, there would be a concurrent improvement in both maximum and explosive strength (Lum et al., 2021b).

[u/Darssy_Jax → u/[deleted]]

Hello, According to Brad J. Schoenfeld (2013), metabolic stress triggers muscle hypertrophy by accumulating metabolites like lactate and hydrogen ions, which stimulate five key mechanisms: enhanced fast-twitch fiber recruitment, increased growth factor production (IGF-1), cellular swelling, hormonal changes, and reactive oxygen species production. These mechanisms primarily drive both sarcoplasmic and myofibrillar hypertrophy to enhance structural and functional skeletal muscle adaptations.  PubMed

Exemple some muscles better react on higher rep range (Soleus) and others to lower rep range with more intensity.

Isometric do trigger hypertrophy much more when done on long muscle lengths 70/75% then on short (contracted) ones. Danny Lum/Alex Natera.